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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.
142
Randy Dunlap53471122008-03-12 18:10:51 -0400143 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
Len Browna1fdcc02007-03-11 03:26:14 -0400145 acpi_apic_instance= [ACPI, IOAPIC]
146 Format: <int>
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400149 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400150
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 acpi_sleep= [HW,ACPI] Sleep options
Rafael J. Wysockiba84ed92008-10-26 20:56:30 +0100152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
153 old_ordering, s4_nonvs }
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800154 See Documentation/power/video.txt for information on
155 s3_bios and s3_mode.
Pavel Machek23b168d2008-02-05 19:27:12 +0100156 s3_beep is for debugging; it makes the PC's speaker beep
157 as soon as the kernel's real-mode entry point is called.
Shaohua Libdfe6b72008-07-23 21:28:41 -0700158 s4_nohwsig prevents ACPI hardware signature from being
159 used during resume from hibernation.
Rafael J. Wysockid8f3de02008-06-12 23:24:06 +0200160 old_ordering causes the ACPI 1.0 ordering of the _PTS
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800161 control method, with respect to putting devices into
162 low power states, to be enforced (the ACPI 2.0 ordering
163 of _PTS is used by default).
Rafael J. Wysockiba84ed92008-10-26 20:56:30 +0100164 s4_nonvs prevents the kernel from saving/restoring the
165 ACPI NVS memory during hibernation.
Randy Dunlapa9913042005-10-23 12:57:11 -0700166
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700168 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
Randy Dunlapa9913042005-10-23 12:57:11 -0700170 acpi_irq_balance [HW,ACPI]
171 ACPI will balance active IRQs
172 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173
Randy Dunlapa9913042005-10-23 12:57:11 -0700174 acpi_irq_nobalance [HW,ACPI]
175 ACPI will not move active IRQs (default)
176 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
Randy Dunlapa9913042005-10-23 12:57:11 -0700178 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
179 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 Format: <irq>,<irq>...
181
Randy Dunlapa9913042005-10-23 12:57:11 -0700182 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 Format: <irq>,<irq>...
184
Len Brown67effe82007-07-26 00:50:06 -0400185 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
186
Len Browna1f9e652006-01-25 23:47:36 -0500187 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
188 Format: To spoof as Windows 98: ="Microsoft Windows"
189
Len Brownae00d812007-05-29 18:43:33 -0400190 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
191 acpi_osi="string1" # add string1 -- only one string
192 acpi_osi="!string2" # remove built-in string2
193 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194
195 acpi_serialize [HW,ACPI] force serialization of AML methods
196
197 acpi_skip_timer_override [HW,ACPI]
198 Recognize and ignore IRQ0/pin2 Interrupt Override.
199 For broken nForce2 BIOS resulting in XT-PIC timer.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800200 acpi_use_timer_override [HW,ACPI]
Andi Kleenfa18f472006-11-14 16:57:46 +0100201 Use timer override. For some broken Nvidia NF5 boards
202 that require a timer override, but don't have
203 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200205 acpi_backlight= [HW,ACPI]
206 acpi_backlight=vendor
207 acpi_backlight=video
208 If set to vendor, prefer vendor specific driver
209 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
210 of the ACPI video.ko driver.
211
212 acpi_display_output= [HW,ACPI]
213 acpi_display_output=vendor
214 acpi_display_output=video
215 See above.
216
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700217 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
218 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700220 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
221 debug output. Bits in debug_layer correspond to a
222 _COMPONENT in an ACPI source file, e.g.,
223 #define _COMPONENT ACPI_PCI_COMPONENT
224 Bits in debug_level correspond to a level in
225 ACPI_DEBUG_PRINT statements, e.g.,
226 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
227 See Documentation/acpi/debug.txt for more information
228 about debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700230 Enable AML "Debug" output, i.e., stores to the Debug
231 object while interpreting AML:
232 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
233 Enable PCI/PCI interrupt routing info messages:
234 acpi.debug_layer=0x400000 acpi.debug_level=0x4
235 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]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800864 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
865 Poll forces a polling idle loop that can slightly
866 improve the performance of waking up a idle CPU, but
867 will use a lot of power and make the system run hot.
868 Not recommended.
869 idle=mwait: On systems which support MONITOR/MWAIT but
870 the kernel chose to not use it because it doesn't save
871 as much power as a normal idle loop, use the
872 MONITOR/MWAIT idle loop anyways. Performance should be
873 the same as idle=poll.
874 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800875 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800876 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700877
Denis Cheng594765a2008-02-06 02:57:49 +0100878 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
879 Claim all unknown PCI IDE storage controllers.
880
Ingo Molnar792908222006-12-06 20:40:51 -0800881 ignore_loglevel [KNL]
882 Ignore loglevel setting - this will print /all/
883 kernel messages to the console. Useful for debugging.
884
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 ihash_entries= [KNL]
886 Set number of hash buckets for inode cache.
887
888 in2000= [HW,SCSI]
889 See header of drivers/scsi/in2000.c.
890
891 init= [KNL]
892 Format: <full_path>
893 Run specified binary instead of /sbin/init as init
894 process.
895
896 initcall_debug [KNL] Trace initcalls as they are executed. Useful
897 for working out where the kernel is dying during
898 startup.
899
900 initrd= [BOOT] Specify the location of the initial ramdisk
901
902 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
903 Format: <irq>
904
905 inttest= [IA64]
906
Pavel Machekb552da82008-03-19 15:58:11 +0100907 iommu= [x86]
908 off
909 force
910 noforce
911 biomerge
912 panic
913 nopanic
914 merge
915 nomerge
916 forcesac
917 soft
918
919
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700920 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
921 off
922 Disable intel iommu driver.
923 igfx_off [Default Off]
924 By default, gfx is mapped as normal device. If a gfx
925 device has a dedicated DMAR unit, the DMAR unit is
926 bypassed by not enabling DMAR with this option. In
927 this case, gfx device will use physical address for
928 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700929 forcedac [x86_64]
930 With this option iommu will not optimize to look
931 for io virtual address below 32 bit forcing dual
932 address cycle on pci bus for cards supporting greater
933 than 32 bit addressing. The default is to look
934 for translation below 32 bit and if not available
935 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800936 strict [Default Off]
937 With this option on every unmap_single operation will
938 result in a hardware IOTLB flush operation as opposed
939 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700940
Rene Hermanb02aae92008-01-30 13:30:05 +0100941 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100942 0x80
943 Standard port 0x80 based delay
944 0xed
945 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100946 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100947 Simple two microseconds delay
948 none
949 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100950
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 io7= [HW] IO7 for Marvel based alpha systems
952 See comment before marvel_specify_io7 in
953 arch/alpha/kernel/core_marvel.c.
954
955 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400956 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957
958 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700959 See comment before ip2_setup() in
960 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961
962 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
963 See header of drivers/scsi/ips.c.
964
Simon Horman72c4a132006-09-13 19:57:18 -0700965 ports= [IP_VS_FTP] IPVS ftp helper module
966 Default is 21.
967 Up to 8 (IP_VS_APP_MAX_PORTS) ports
968 may be specified.
969 Format: <port>,<port>....
970
Alan Cox200803d2005-06-28 20:45:18 -0700971 irqfixup [HW]
972 When an interrupt is not handled search all handlers
973 for it. Intended to get systems with badly broken
974 firmware running.
975
976 irqpoll [HW]
977 When an interrupt is not handled search all handlers
978 for it. Also check all handlers each timer
979 interrupt. Intended to get systems with badly broken
980 firmware running.
981
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700983 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984
985 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800986 Format:
987 <cpu number>,...,<cpu number>
988 or
Li Zefanb225d442008-11-06 12:53:39 -0800989 <cpu number>-<cpu number>
990 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -0800991 or a mixture
992 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -0800993
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 This option can be used to specify one or more CPUs
995 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -0800996 algorithms. You can move a process onto or off an
997 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 <cpu number> begins at 0 and the maximum value is
999 "number of CPUs in system - 1".
1000
1001 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001002 alternative -- manually setting the CPU mask of all
1003 tasks in the system -- can cause problems and
1004 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005
Randy Dunlapa9913042005-10-23 12:57:11 -07001006 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007
1008 js= [HW,JOY] Analog joystick
1009 See Documentation/input/joystick.txt.
1010
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001011 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001012 specifies the amount of memory usable by the kernel
1013 for non-movable allocations. The requested amount is
1014 spread evenly throughout all nodes in the system. The
1015 remaining memory in each node is used for Movable
1016 pages. In the event, a node is too small to have both
1017 kernelcore and Movable pages, kernelcore pages will
1018 take priority and other nodes will have a larger number
1019 of kernelcore pages. The Movable zone is used for the
1020 allocation of pages that may be reclaimed or moved
1021 by the page migration subsystem. This means that
1022 HugeTLB pages may not be allocated from this zone.
1023 Note that allocations like PTEs-from-HighMem still
1024 use the HighMem zone if it exists, and the Normal
1025 zone if it does not.
1026
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001027 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -07001028 is similar to kernelcore except it specifies the
1029 amount of memory used for migratable allocations.
1030 If both kernelcore and movablecore is specified,
1031 then kernelcore will be at *least* the specified
1032 value but may be more. If movablecore on its own
1033 is specified, the administrator must be careful
1034 that the amount of memory usable for all allocations
1035 is not too small.
1036
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 keepinitrd [HW,ARM]
1038
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001039 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 in oops dumps.
1041
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001042 kgdboc= [HW] kgdb over consoles.
1043 Requires a tty driver that supports console polling.
1044 (only serial suported for now)
1045 Format: <serial_device>[,baud]
1046
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001047 kmac= [MIPS] korina ethernet MAC address.
1048 Configure the RouterBoard 532 series on-chip
1049 Ethernet adapter MAC address.
1050
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 l2cr= [PPC]
1052
Robert Brosea78bfbf2008-03-29 07:20:23 +11001053 l3cr= [PPC]
1054
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001055 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001056 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001058 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1059 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001060
FD Camifcb71f62008-01-06 19:08:56 +01001061 libata.dma= [LIBATA] DMA control
1062 libata.dma=0 Disable all PATA and SATA DMA
1063 libata.dma=1 PATA and SATA Disk DMA only
1064 libata.dma=2 ATAPI (CDROM) DMA only
1065 libata.dma=4 Compact Flash DMA only
1066 Combinations also work, so libata.dma=3 enables DMA
1067 for disks and CDROMs, but not CFs.
1068
Dave Jones78e70c22007-09-27 11:50:13 -04001069 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1070 when set.
1071 Format: <int>
1072
Tejun Heo33267322008-02-13 09:15:09 +09001073 libata.force= [LIBATA] Force configurations. The format is comma
1074 separated list of "[ID:]VAL" where ID is
1075 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1076 matching port, link or device. Basically, it matches
1077 the ATA ID string printed on console by libata. If
1078 the whole ID part is omitted, the last PORT and DEVICE
1079 values are used. If ID hasn't been specified yet, the
1080 configuration applies to all ports, links and devices.
1081
1082 If only DEVICE is omitted, the parameter applies to
1083 the port and all links and devices behind it. DEVICE
1084 number of 0 either selects the first device or the
1085 first fan-out link behind PMP device. It does not
1086 select the host link. DEVICE number of 15 selects the
1087 host link and device attached to it.
1088
1089 The VAL specifies the configuration to force. As long
1090 as there's no ambiguity shortcut notation is allowed.
1091 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1092 The following configurations can be forced.
1093
1094 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1095 Any ID with matching PORT is used.
1096
1097 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1098
1099 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1100 udma[/][16,25,33,44,66,100,133] notation is also
1101 allowed.
1102
1103 * [no]ncq: Turn on or off NCQ.
1104
Tejun Heo05944bd2008-08-13 20:19:09 +09001105 * nohrst, nosrst, norst: suppress hard, soft
1106 and both resets.
1107
Tejun Heo33267322008-02-13 09:15:09 +09001108 If there are multiple matching configurations changing
1109 the same attribute, the last one is used.
1110
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001112 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001114 lockd.nlm_grace_period=P [NFS] Assign grace period.
1115 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001117 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1118 Format: <integer>
1119
1120 lockd.nlm_timeout=T [NFS] Assign timeout value.
1121 Format: <integer>
1122
1123 lockd.nlm_udpport=M [NFS] Assign UDP port.
1124 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125
1126 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1127 Format: <irq>
1128
1129 loglevel= All Kernel Messages with a loglevel smaller than the
1130 console loglevel will be printed to the console. It can
1131 also be changed with klogd or other programs. The
1132 loglevels are defined as follows:
1133
1134 0 (KERN_EMERG) system is unusable
1135 1 (KERN_ALERT) action must be taken immediately
1136 2 (KERN_CRIT) critical conditions
1137 3 (KERN_ERR) error conditions
1138 4 (KERN_WARNING) warning conditions
1139 5 (KERN_NOTICE) normal but significant condition
1140 6 (KERN_INFO) informational
1141 7 (KERN_DEBUG) debug-level messages
1142
1143 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001144 Format: { n | nk | nM }
1145 n must be a power of two. The default size
1146 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147
Randy Dunlapaccaa242007-10-16 01:29:37 -07001148 logo.nologo [FB] Disables display of the built-in Linux logo.
1149 This may be used to provide more screen space for
1150 kernel log messages and is useful when debugging
1151 kernel boot problems.
1152
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 lp=0 [LP] Specify parallel ports to use, e.g,
1154 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1155 lp=reset first parallel port). 'lp=0' disables the
1156 lp=auto printer driver. 'lp=reset' (which can be
1157 specified in addition to the ports) causes
1158 attached printers to be reset. Using
1159 lp=port1,port2,... specifies the parallel ports
1160 to associate lp devices with, starting with
1161 lp0. A port specification may be 'none' to skip
1162 that lp device, or a parport name such as
1163 'parport0'. Specifying 'lp=auto' instead of a
1164 port specification list means that device IDs
1165 from each port should be examined, to see if
1166 an IEEE 1284-compliant printer is attached; if
1167 so, the driver will manage that printer.
1168 See also header of drivers/char/lp.c.
1169
1170 lpj=n [KNL]
1171 Sets loops_per_jiffy to given constant, thus avoiding
1172 time-consuming boot-time autodetection (up to 250 ms per
1173 CPU). 0 enables autodetection (default). To determine
1174 the correct value for your kernel, boot with normal
1175 autodetection and see what value is printed. Note that
1176 on SMP systems the preset will be applied to all CPUs,
1177 which is likely to cause problems if your CPUs need
1178 significantly divergent settings. An incorrect value
1179 will cause delays in the kernel to be wrong, leading to
1180 unpredictable I/O errors and other breakage. Although
1181 unlikely, in the extreme case this might damage your
1182 hardware.
1183
1184 ltpc= [NET]
1185 Format: <io>,<irq>,<dma>
1186
Randy Dunlapa9913042005-10-23 12:57:11 -07001187 mac5380= [HW,SCSI] Format:
1188 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189
Randy Dunlapa9913042005-10-23 12:57:11 -07001190 machvec= [IA64] Force the use of a particular machine-vector
1191 (machvec) in a generic kernel.
1192 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193
Randy Dunlapa9913042005-10-23 12:57:11 -07001194 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 be mounted
1196 Format: <1-256>
1197
1198 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001199 should make use of. maxcpus=n : n >= 0 limits the
1200 kernel to using 'n' processors. n=0 is a special case,
1201 it is equivalent to "nosmp", which also disables
1202 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203
Randy Dunlap1c207f92008-11-19 15:36:16 -08001204 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1205 or equal to this physical address is ignored.
Bob Picco2b2c3752005-06-29 18:00:00 -07001206
Randy Dunlapa9913042005-10-23 12:57:11 -07001207 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208 Should be between 1 and 2^32-1.
1209
1210 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001211 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 Should be between 1 and 16384.
1213
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 mcatest= [IA-64]
1215
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001216 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217
Uwe Hermann71cced62008-10-20 09:32:21 -07001218 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001219
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 md= [HW] RAID subsystems devices and level
1221 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001222
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223 mdacon= [MDA]
1224 Format: <first>,<last>
1225 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001226
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1228 Amount of memory to be used when the kernel is not able
1229 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001230 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 address space collisions. Without memmap= PCI devices
1232 could be placed at addresses belonging to unused RAM.
1233
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001234 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 memory.
1236
Paul Mundt6902aa82008-09-21 17:14:42 +09001237 memchunk=nn[KMG]
1238 [KNL,SH] Allow user to override the default size for
1239 per-device physically contiguous DMA buffers.
1240
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001241 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 E820 memory map, as specified by the user.
1243 Such memmap=exactmap lines can be constructed based on
1244 BIOS output or other requirements. See the memmap=nn@ss
1245 option description.
1246
1247 memmap=nn[KMG]@ss[KMG]
1248 [KNL] Force usage of a specific region of memory
1249 Region of memory to be used, from ss to ss+nn.
1250
1251 memmap=nn[KMG]#ss[KMG]
1252 [KNL,ACPI] Mark specific memory as ACPI data.
1253 Region of memory to be used, from ss to ss+nn.
1254
1255 memmap=nn[KMG]$ss[KMG]
1256 [KNL,ACPI] Mark specific memory as reserved.
1257 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001258 Example: Exclude memory from 0x18690000-0x1869ffff
1259 memmap=64K$0x18690000
1260 or
1261 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001262
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001263 memory_corruption_check=0/1 [X86]
1264 Some BIOSes seem to corrupt the first 64k of
1265 memory when doing things like suspend/resume.
1266 Setting this option will scan the memory
1267 looking for corruption. Enabling this will
1268 both detect corruption and prevent the kernel
1269 from using the memory being corrupted.
1270 However, its intended as a diagnostic tool; if
1271 repeatable BIOS-originated corruption always
1272 affects the same memory, you can use memmap=
1273 to prevent the kernel from using that memory.
1274
1275 memory_corruption_check_size=size [X86]
1276 By default it checks for corruption in the low
1277 64k, making this memory unavailable for normal
1278 use. Use this parameter to scan for
1279 corruption in more or less memory.
1280
1281 memory_corruption_check_period=seconds [X86]
1282 By default it checks for corruption every 60
1283 seconds. Use this parameter to check at some
1284 other rate. 0 disables periodic checking.
1285
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001286 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001287 Format: <integer>
1288 range: 0,4 : pattern number
1289 default : 0 <disable>
1290
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291 meye.*= [HW] Set MotionEye Camera parameters
1292 See Documentation/video4linux/meye.txt.
1293
Andres Salomon8f368812007-10-12 23:04:06 +02001294 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1295 Multi-Function General Purpose Timers on AMD Geode
1296 platforms.
1297
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001298 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1299 the BIOS has incorrectly applied a workaround. TinyBIOS
1300 version 0.98 is known to be affected, 0.99 fixes the
1301 problem by letting the user disable the workaround.
1302
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 mga= [HW,DRM]
1304
Randy Dunlap1c207f92008-11-19 15:36:16 -08001305 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1306 physical address is ignored.
1307
Mel Gorman6b74ab92008-07-23 21:26:49 -07001308 mminit_loglevel=
1309 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1310 parameter allows control of the logging verbosity for
1311 the additional memory initialisation checks. A value
1312 of 0 disables mminit logging and a level of 4 will
1313 log everything. Information is printed at KERN_DEBUG
1314 so loglevel=8 may also need to be specified.
1315
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 mousedev.tap_time=
1317 [MOUSE] Maximum time between finger touching and
1318 leaving touchpad surface for touch to be considered
1319 a tap and be reported as a left button click (for
1320 touchpads working in absolute mode only).
1321 Format: <msecs>
1322 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1323 reporting absolute coordinates, such as tablets
1324 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1325 reporting absolute coordinates, such as tablets
1326
1327 mpu401= [HW,OSS]
1328 Format: <io>,<irq>
1329
1330 MTD_Partition= [MTD]
1331 Format: <name>,<region-number>,<size>,<offset>
1332
Randy Dunlapa9913042005-10-23 12:57:11 -07001333 MTD_Region= [MTD] Format:
1334 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335
1336 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001337 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338
Ben Dooks9db829f2008-07-03 11:24:29 +01001339 mtdset= [ARM]
1340 ARM/S3C2412 JIVE boot control
1341
1342 See arch/arm/mach-s3c2412/mach-jive.c
1343
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001345 [HW] Make the MicroTouch USB driver use raw coordinates
1346 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347
1348 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1349
1350 NCR_D700= [HW,SCSI]
1351 See header of drivers/scsi/NCR_D700.c.
1352
1353 ncr5380= [HW,SCSI]
1354
1355 ncr53c400= [HW,SCSI]
1356
1357 ncr53c400a= [HW,SCSI]
1358
1359 ncr53c406a= [HW,SCSI]
1360
1361 ncr53c8xx= [HW,SCSI]
1362
1363 netdev= [NET] Network devices parameters
1364 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1365 Note that mem_start is often overloaded to mean
1366 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001367 This usage is only documented in each driver source
1368 file if at all.
1369
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001370 nf_conntrack.acct=
1371 [NETFILTER] Enable connection tracking flow accounting
1372 0 to disable accounting
1373 1 to enable accounting
1374 Default value depends on CONFIG_NF_CT_ACCT that is
1375 going to be removed in 2.6.29.
1376
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001378 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
1380 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001381 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382
Trond Myklebusta72b4422006-01-03 09:55:41 +01001383 nfs.callback_tcpport=
1384 [NFS] set the TCP port on which the NFSv4 callback
1385 channel should listen.
1386
Trond Myklebust58df0952006-01-03 09:55:57 +01001387 nfs.idmap_cache_timeout=
1388 [NFS] set the maximum lifetime for idmapper cache
1389 entries.
1390
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001391 nfs.enable_ino64=
1392 [NFS] enable 64-bit inode numbers.
1393 If zero, the NFS client will fake up a 32-bit inode
1394 number for the readdir() and stat() syscalls instead
1395 of returning the full 64-bit number.
1396 The default is to return 64-bit inode numbers.
1397
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001398 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1399 when a NMI is triggered.
1400 Format: [state][,regs][,debounce][,die]
1401
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001402 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001404 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 emulation library even if a 387 maths coprocessor
1406 is present.
1407
Christoph Lameterc1aee212007-05-31 00:40:47 -07001408 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1409 caches in the slab allocator. Saves per-node memory,
1410 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001411
Randy Dunlapa9913042005-10-23 12:57:11 -07001412 noalign [KNL,ARM]
1413
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 noapic [SMP,APIC] Tells the kernel to not make use of any
1415 IOAPICs that may be present in the system.
1416
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 nobats [PPC] Do not use BATs for mapping kernel lowmem
1418 on "Classic" PPC cores.
1419
1420 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001421
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001422 nodelayacct [KNL] Disable per-task delay accounting
1423
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1425
Paul Mundt6902aa82008-09-21 17:14:42 +09001426 nodsp [SH] Disable hardware DSP at boot time.
1427
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001428 noefi [X86-32,X86-64] Disable EFI runtime services support.
1429
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430 noexec [IA-64]
1431
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001432 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001433 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001435 noexec=off: disable non-executable mappings
1436
1437 noexec32 [X86-64]
1438 This affects only 32-bit executables.
1439 noexec32=on: enable non-executable mappings (default)
1440 read doesn't imply executable mappings
1441 noexec32=off: disable non-executable mappings
1442 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443
Paul Mundt6902aa82008-09-21 17:14:42 +09001444 nofpu [SH] Disable hardware FPU at boot time.
1445
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001446 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001447 register save and restore. The kernel will only save
1448 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449
Andi Kleen191679f2008-01-30 13:33:21 +01001450 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1451
Paul Mundt6902aa82008-09-21 17:14:42 +09001452 nohlt [BUGS=ARM,SH]
Randy Dunlapa9913042005-10-23 12:57:11 -07001453
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001454 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 instruction doesn't work correctly and not to
1456 use it.
1457
1458 nohalt [IA-64] Tells the kernel not to use the power saving
1459 function PAL_HALT_LIGHT when idle. This increases
1460 power-consumption. On the positive side, it reduces
1461 interrupt wake-up latency, which may improve performance
1462 in certain environments such as networked servers or
1463 real-time systems.
1464
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001465 nohz= [KNL] Boottime enable/disable dynamic ticks
1466 Valid arguments: on, off
1467 Default: on
1468
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001469 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 disable unhandled interrupt sources.
1471
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001472 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001473 broken timer IRQ sources.
1474
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 noisapnp [ISAPNP] Disables ISA PnP code.
1476
1477 noinitrd [RAM] Tells the kernel not to load any configured
1478 initial RAM disk.
1479
1480 nointroute [IA-64]
1481
Tony Luck0aa366f2007-07-20 11:22:30 -07001482 nojitter [IA64] Disables jitter checking for ITC timers.
1483
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001484 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001486 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001487
Suresh Siddha6e1cb382008-07-10 11:16:58 -07001488 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1489
Suresh Siddhaaf9d1382008-07-11 13:11:57 -07001490 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1491 default x2apic cluster mode on platforms
1492 supporting x2apic.
1493
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494 noltlbs [PPC] Do not use large page/tlb entries for kernel
1495 lowmem mapping on PPC40x.
1496
Horms312f1f02006-02-22 09:57:55 +09001497 nomca [IA-64] Disable machine check abort handling
1498
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001499 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001500
Andres Salomon83d73842007-10-12 23:04:06 +02001501 nomfgpt [X86-32] Disable Multi-Function General Purpose
1502 Timer usage (for AMD Geode machines).
1503
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001504 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001505
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001506 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001507 with UP alternatives
1508
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 noresidual [PPC] Don't use residual data on PReP machines.
1510
Randy Dunlapa9913042005-10-23 12:57:11 -07001511 noresume [SWSUSP] Disables resume and restores original swap
1512 space.
1513
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 no-scroll [VGA] Disables scrollback.
1515 This is required for the Braillex ib80-piezo Braille
1516 reader made by F.H. Papenmeier (Germany).
1517
1518 nosbagart [IA-64]
1519
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001520 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001521
Len Brown61ec7562007-08-16 03:34:22 -04001522 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1523 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524
Dave Jones97842212007-07-15 23:41:05 -07001525 nosoftlockup [KNL] Disable the soft-lockup detector.
1526
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 nosync [HW,M68K] Disables sync negotiation for all devices.
1528
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001529 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530
1531 nousb [USB] Disable the USB subsystem
1532
1533 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001534
Fenghua Yua6c75b862008-03-14 13:57:08 -07001535 nptcg= [IA64] Override max number of concurrent global TLB
1536 purges which is reported from either PAL_VM_SUMMARY or
1537 SAL PALO.
1538
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001539 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1540 one of ['zone', 'node', 'default'] can be specified
1541 This can be set from sysctl after boot.
1542 See Documentation/sysctl/vm.txt for details.
1543
Dave Jonesa61c2d72006-01-07 23:18:19 +00001544 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1545
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001546 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1547 Rather than timing out after 20 ms if an EC
1548 command is not properly ACKed, override the length
1549 of the timeout. We have interrupts disabled while
1550 waiting for the ACK, so if this is set too high
1551 interrupts *may* be lost!
1552
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 opl3= [HW,OSS]
1554 Format: <io>
1555
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 oprofile.timer= [HW]
1557 Use timer interrupt instead of performance counters
1558
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 osst= [HW,SCSI] SCSI Tape Driver
1560 Format: <buffer_size>,<write_threshold>
1561 See also Documentation/scsi/st.txt.
1562
1563 panic= [KNL] Kernel behaviour on panic
1564 Format: <timeout>
1565
1566 parkbd.port= [HW] Parallel port number the keyboard adapter is
1567 connected to, default is 0.
1568 Format: <parport#>
1569 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1570 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001571 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572
Randy Dunlapa9913042005-10-23 12:57:11 -07001573 parport= [HW,PPT] Specify parallel ports. 0 disables.
1574 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1575 Use 'auto' to force the driver to use any
1576 IRQ/DMA settings detected (the default is to
1577 ignore detected IRQ/DMA settings because of
1578 possible conflicts). You can specify the base
1579 address, IRQ, and DMA settings; IRQ and DMA
1580 should be numbers, or 'auto' (for using detected
1581 settings on that particular port), or 'nofifo'
1582 (to avoid using a FIFO even if it is detected).
1583 Parallel ports are assigned in the order they
1584 are specified on the command line, starting
1585 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586
Randy Dunlapa9913042005-10-23 12:57:11 -07001587 parport_init_mode= [HW,PPT]
1588 Configure VIA parallel port to operate in
1589 a specific mode. This is necessary on Pegasos
1590 computer where firmware has no options for setting
1591 up parallel port mode and sets it to spp.
1592 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 Format: [spp|ps2|epp|ecp|ecpepp]
1594
Randy Dunlapa9913042005-10-23 12:57:11 -07001595 pas2= [HW,OSS] Format:
1596 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1597
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598 pas16= [HW,SCSI]
1599 See header of drivers/scsi/pas16.c.
1600
Andrew Mortondd287792006-03-23 03:00:57 -08001601 pause_on_oops=
1602 Halt all CPUs after the first oops has been printed for
1603 the specified number of seconds. This is to be used if
1604 your oopses keep scrolling off the screen.
1605
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606 pcbit= [HW,ISDN]
1607
1608 pcd. [PARIDE]
1609 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001610 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611
Randy Dunlapa9913042005-10-23 12:57:11 -07001612 pci=option[,option...] [PCI] various PCI subsystem options:
Andi Kleenc0115602008-08-22 09:53:39 +02001613 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001614 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001615 the hardware directly. Use this if your machine
1616 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001617 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001618 hardware access methods are allowed. Use this
1619 if you experience crashes upon bootup and you
1620 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001621 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001622 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001623 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001624 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001625 noaer [PCIE] If the PCIEAER kernel config parameter is
1626 enabled, this kernel boot option can be used to
1627 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001628 nodomains [PCI] Disable support for multiple PCI
1629 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001630 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001631 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001632 nomsi [MSI] If the PCI_MSI kernel config parameter is
1633 enabled, this kernel boot option can be used to
1634 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001635 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001636 routing table. These calls are known to be buggy
1637 on several machines and they hang the machine
1638 when used, but on other computers it's the only
1639 way to get the interrupt routing table. Try
1640 this option if the kernel is unable to allocate
1641 IRQs or discover secondary PCI buses on your
1642 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001643 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001644 Use with caution as certain devices share
1645 address decoders between ROMs and other
1646 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001647 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001648 expansion ROMs that do not already have
1649 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001650 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001651 assigned automatically to PCI devices. You can
1652 make the kernel exclude IRQs of your ISA cards
1653 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001654 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001655 of the PIRQ table (normally generated
1656 by the BIOS) if it is outside the
1657 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001658 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001659 useful if the kernel is unable to find your
1660 secondary buses and you want to tell it
1661 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001662 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001663 numbers ourselves, overriding
1664 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001665 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001666 in the BIOS $PIR table. This is needed on
1667 some systems with broken BIOSes, notably
1668 some HP Pavilion N5400 and Omnibook XE3
1669 notebooks. This will have no effect if ACPI
1670 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001671 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001672 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001673 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001674 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001675 routeirq Do IRQ routing for all PCI devices.
1676 This is normally done in pci_enable_device(),
1677 so this option is a temporary workaround
1678 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001679 skip_isa_align [X86] do not align io start addr, so can
1680 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001681 firmware [ARM] Do not re-enumerate the bus but instead
1682 just use the configuration from the
1683 bootloader. This is currently used on
1684 IXP2000 systems where the bus has to be
1685 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001686 noearly [X86] Don't do any early type 1 scanning.
1687 This might help on some broken boards which
1688 machine check when some devices' config space
1689 is read. But various workarounds are disabled
1690 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001691 bfsort Sort PCI devices into breadth-first order.
1692 This sorting is done to get a device
1693 order compatible with older (<= 2.4) kernels.
1694 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001695 cbiosize=nn[KMG] The fixed amount of bus space which is
1696 reserved for the CardBus bridge's IO window.
1697 The default value is 256 bytes.
1698 cbmemsize=nn[KMG] The fixed amount of bus space which is
1699 reserved for the CardBus bridge's memory
1700 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001701
Chuck Ebberte5665a42008-09-24 20:40:34 -04001702 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1703 Management.
1704 off Disable ASPM.
1705 force Enable ASPM even on devices that claim not to support it.
1706 WARNING: Forcing ASPM on may cause system lockups.
1707
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708 pcmv= [HW,PCMCIA] BadgePAD 4
1709
1710 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001711 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712
1713 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1714 boot time.
1715 Format: { 0 | 1 }
1716 See arch/parisc/kernel/pdc_chassis.c
1717
1718 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001719 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720
1721 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001722 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723
1724 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001725 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726
1727 plip= [PPT,NET] Parallel port network link
1728 Format: { parport<nr> | timid | 0 }
1729 See also Documentation/parport.txt.
1730
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001731 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1732 Override pmtimer IOPort with a hex value.
1733 e.g. pmtmr=0x508
1734
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001735 pnp.debug [PNP]
1736 Enable PNP debug messages. This depends on the
1737 CONFIG_PNP_DEBUG_MESSAGES option.
1738
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 pnpacpi= [ACPI]
1740 { off }
1741
1742 pnpbios= [ISAPNP]
1743 { on | off | curr | res | no-curr | no-res }
1744
1745 pnp_reserve_irq=
1746 [ISAPNP] Exclude IRQs for the autoconfiguration
1747
1748 pnp_reserve_dma=
1749 [ISAPNP] Exclude DMAs for the autoconfiguration
1750
1751 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001752 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753
1754 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001755 [ISAPNP] Exclude memory regions for the
1756 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 Ranges are in pairs (memory base and size).
1758
Jason Baron346e15b2008-08-12 16:46:19 -04001759 dynamic_printk
1760 Enables pr_debug()/dev_dbg() calls if
1761 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1762 be switched on/off via <debugfs>/dynamic_printk/modules
1763
Ingo Molnar45807a12007-07-15 23:40:10 -07001764 print-fatal-signals=
1765 [KNL] debug: print fatal signals
1766 print-fatal-signals=1: print segfault info to
1767 the kernel console.
1768 default: off.
1769
Randy Dunlape84845c2007-07-15 23:40:25 -07001770 printk.time= Show timing data prefixed to each printk message line
1771 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1772
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001774 Format: [schedule,]<number>
1775 Param: "schedule" - profile schedule points.
1776 Param: <number> - step/bucket size as a power of 2 for
1777 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001778 Param: "sleep" - profile D-state sleeping (millisecs).
1779 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001780 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781
Randy Dunlapa9913042005-10-23 12:57:11 -07001782 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 Limit processor to maximum C-state
1784 max_cstate=9 overrides any DMI blacklist limit.
1785
Len Brown41c0d862005-12-28 12:43:51 -05001786 processor.nocst [HW,ACPI]
1787 Ignore the _CST method to determine C-states,
1788 instead using the legacy FADT method
1789
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1791 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001792 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793
Randy Dunlapa9913042005-10-23 12:57:11 -07001794 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1795 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1797 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001798 psmouse.resetafter= [HW,MOUSE]
1799 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 (0 = never).
1801 psmouse.resolution=
1802 [HW,MOUSE] Set desired mouse resolution, in dpi.
1803 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001804 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001805 0 = disabled, 1 = enabled (default).
1806
1807 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001808 Format:
1809 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810
1811 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001812 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
Kay Sieversdc8c8582007-08-15 12:25:38 +02001814 pty.legacy_count=
1815 [KNL] Number of legacy pty's. Overwrites compiled-in
1816 default number.
1817
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001818 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001819
Linus Torvalds1da177e2005-04-16 15:20:36 -07001820 r128= [HW,DRM]
1821
1822 raid= [HW,RAID]
1823 See Documentation/md.txt.
1824
Randy Dunlapa9913042005-10-23 12:57:11 -07001825 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001826 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001827
Linus Torvalds1da177e2005-04-16 15:20:36 -07001828 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001829 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001831 rcupdate.blimit= [KNL,BOOT]
1832 Set maximum number of finished RCU callbacks to process
1833 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001834
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001835 rcupdate.qhimark= [KNL,BOOT]
1836 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001837 RCU callbacks over which batch limiting is disabled.
1838
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001839 rcupdate.qlowmark= [KNL,BOOT]
1840 Set threshold of queued RCU callbacks below which
1841 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001842
Olof Johanssonffdfc402005-09-06 15:17:19 -07001843 rdinit= [KNL]
1844 Format: <full_path>
1845 Run specified binary instead of /init from the ramdisk,
1846 used for early userspace startup. See initrd.
1847
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001848 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001850 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851
Paul Jackson46b6d942008-07-04 10:00:09 -07001852 relax_domain_level=
1853 [KNL, SMP] Set scheduler's default relax_domain_level.
1854 See Documentation/cpusets.txt.
1855
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1857
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001858 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07001859 Format: nn[KMG]
1860 Reserves a hole at the top of the kernel virtual
1861 address space.
1862
Vivek Goyal7e962872006-09-27 01:50:44 -07001863 reset_devices [KNL] Force drivers to reset the underlying device
1864 during initialization.
1865
Randy Dunlapa9913042005-10-23 12:57:11 -07001866 resume= [SWSUSP]
1867 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001869 resume_offset= [SWSUSP]
1870 Specify the offset from the beginning of the partition
1871 given by "resume=" at which the swap header is located,
1872 in <PAGE_SIZE> units (needed only for swap files).
1873 See Documentation/power/swsusp-and-swap-files.txt
1874
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001875 retain_initrd [RAM] Keep initrd memory after extraction
1876
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 rhash_entries= [KNL,NET]
1878 Set number of hash buckets for route cache
1879
1880 riscom8= [HW,SERIAL]
1881 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1882
1883 ro [KNL] Mount root device read-only on boot
1884
1885 root= [KNL] Root filesystem
1886
1887 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1888 mount the root filesystem
1889
1890 rootflags= [KNL] Set root filesystem mount option string
1891
1892 rootfstype= [KNL] Set root filesystem type
1893
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001894 rootwait [KNL] Wait (indefinitely) for root device to show up.
1895 Useful for devices that are detected asynchronously
1896 (e.g. USB and MMC devices).
1897
James Morris20510f22007-10-16 23:31:32 -07001898 root_plug.vendor_id=
1899 [ROOTPLUG] Override the default vendor ID
1900
1901 root_plug.product_id=
1902 [ROOTPLUG] Override the default product ID
1903
1904 root_plug.debug=
1905 [ROOTPLUG] Enable debugging output
1906
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 rw [KNL] Mount root device read-write on boot
1908
1909 S [KNL] Run init in single mode
1910
1911 sa1100ir [NET]
1912 See drivers/net/irda/sa1100_ir.c.
1913
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001915
Linus Torvalds1da177e2005-04-16 15:20:36 -07001916 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1917 Format: <io>[,<timeout>[,<isapnp>]]
1918
1919 scsi_debug_*= [SCSI]
1920 See drivers/scsi/scsi_debug.c.
1921
1922 scsi_default_dev_flags=
1923 [SCSI] SCSI default device flags
1924 Format: <integer>
1925
1926 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1927 Format: <vendor>:<model>:<flags>
1928 (flags are integer value)
1929
Randy Dunlap6af66322007-11-14 16:52:25 -08001930 scsi_logging_level= [SCSI] a bit mask of logging levels
1931 See drivers/scsi/scsi_logging.h for bits. Also
1932 settable via sysctl at dev.scsi.logging_level
1933 (/proc/sys/dev/scsi/logging_level).
1934 There is also a nice 'scsi_logging_level' script in the
1935 S390-tools package, available for download at
1936 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001938 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1939 discovered. async scans them in kernel threads,
1940 allowing boot to proceed. none ignores them, expecting
1941 user space to do the scan.
1942
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 selinux [SELINUX] Disable or enable SELinux at boot time.
1944 Format: { "0" | "1" }
1945 See security/selinux/Kconfig help text.
1946 0 -- disable.
1947 1 -- enable.
1948 Default value is set via kernel config option.
1949 If enabled at boot time, /selinux/disable can be used
1950 later to disable prior to initial policy load.
1951
James Morris4e5ab4c2006-06-09 00:33:33 -07001952 selinux_compat_net =
1953 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001954 Format: { "0" | "1" }
1955 0 -- use new secmark-based packet controls
1956 1 -- use legacy packet controls
1957 Default value is 0 (preferred).
1958 Value can be changed at runtime via
1959 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001960
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001961 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001962
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 shapers= [NET]
1964 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001965
Yinghai Lub05f78f2008-08-22 01:32:50 -07001966 show_msr= [x86] show boot-time MSR settings
1967 Format: { <integer> }
1968 Show boot-time (BIOS-initialized) MSR settings.
1969 The parameter means the number of CPUs to show,
1970 for example 1 means boot CPU only.
1971
Linus Torvalds1da177e2005-04-16 15:20:36 -07001972 sim710= [SCSI,HW]
1973 See header of drivers/scsi/sim710.c.
1974
1975 simeth= [IA-64]
1976 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001977
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 slram= [HW,MTD]
1979
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001980 slub_debug[=options[,slabs]] [MM, SLUB]
1981 Enabling slub_debug allows one to determine the
1982 culprit if slab objects become corrupted. Enabling
1983 slub_debug can create guard zones around objects and
1984 may poison objects when not in use. Also tracks the
1985 last alloc / free. For more information see
1986 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001987
1988 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001989 Determines the maximum allowed order for slabs.
1990 A high setting may cause OOMs due to memory
1991 fragmentation. For more information see
1992 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001993
1994 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001995 The minimum number of objects per slab. SLUB will
1996 increase the slab order up to slub_max_order to
1997 generate a sufficiently large slab able to contain
1998 the number of objects indicated. The higher the number
1999 of objects the smaller the overhead of tracking slabs
2000 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002001 For more information see Documentation/vm/slub.txt.
2002
2003 slub_min_order= [MM, SLUB]
2004 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002005 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002006 For more information see Documentation/vm/slub.txt.
2007
2008 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002009 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002010 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002011 allocs to different slabs. Debug options disable
2012 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002013 For more information see Documentation/vm/slub.txt.
2014
Linus Torvalds1da177e2005-04-16 15:20:36 -07002015 smart2= [HW]
2016 Format: <io1>[,<io2>[,...,<io8>]]
2017
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002018 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002019 attempt to substitute SMP alternatives once at boot.
2020
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002021 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2022 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2023 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2024 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2025 smsc-ircc2.ircc_irq= [HW] IRQ line
2026 smsc-ircc2.ircc_dma= [HW] DMA channel
2027 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2028 0: Toshiba Satellite 1800 (GP data pin select)
2029 1: Fast pin select (default)
2030 2: ATC IRMode
2031
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 snd-ad1816a= [HW,ALSA]
2033
2034 snd-ad1848= [HW,ALSA]
2035
2036 snd-ali5451= [HW,ALSA]
2037
2038 snd-als100= [HW,ALSA]
2039
2040 snd-als4000= [HW,ALSA]
2041
2042 snd-azt2320= [HW,ALSA]
2043
2044 snd-cmi8330= [HW,ALSA]
2045
2046 snd-cmipci= [HW,ALSA]
2047
2048 snd-cs4231= [HW,ALSA]
2049
2050 snd-cs4232= [HW,ALSA]
2051
2052 snd-cs4236= [HW,ALSA]
2053
2054 snd-cs4281= [HW,ALSA]
2055
2056 snd-cs46xx= [HW,ALSA]
2057
2058 snd-dt019x= [HW,ALSA]
2059
2060 snd-dummy= [HW,ALSA]
2061
2062 snd-emu10k1= [HW,ALSA]
2063
2064 snd-ens1370= [HW,ALSA]
2065
2066 snd-ens1371= [HW,ALSA]
2067
2068 snd-es968= [HW,ALSA]
2069
2070 snd-es1688= [HW,ALSA]
2071
2072 snd-es18xx= [HW,ALSA]
2073
2074 snd-es1938= [HW,ALSA]
2075
2076 snd-es1968= [HW,ALSA]
2077
2078 snd-fm801= [HW,ALSA]
2079
2080 snd-gusclassic= [HW,ALSA]
2081
2082 snd-gusextreme= [HW,ALSA]
2083
2084 snd-gusmax= [HW,ALSA]
2085
2086 snd-hdsp= [HW,ALSA]
2087
2088 snd-ice1712= [HW,ALSA]
2089
2090 snd-intel8x0= [HW,ALSA]
2091
2092 snd-interwave= [HW,ALSA]
2093
2094 snd-interwave-stb=
2095 [HW,ALSA]
2096
2097 snd-korg1212= [HW,ALSA]
2098
2099 snd-maestro3= [HW,ALSA]
2100
2101 snd-mpu401= [HW,ALSA]
2102
2103 snd-mtpav= [HW,ALSA]
2104
2105 snd-nm256= [HW,ALSA]
2106
2107 snd-opl3sa2= [HW,ALSA]
2108
2109 snd-opti92x-ad1848=
2110 [HW,ALSA]
2111
2112 snd-opti92x-cs4231=
2113 [HW,ALSA]
2114
2115 snd-opti93x= [HW,ALSA]
2116
2117 snd-pmac= [HW,ALSA]
2118
2119 snd-rme32= [HW,ALSA]
2120
2121 snd-rme96= [HW,ALSA]
2122
2123 snd-rme9652= [HW,ALSA]
2124
2125 snd-sb8= [HW,ALSA]
2126
2127 snd-sb16= [HW,ALSA]
2128
2129 snd-sbawe= [HW,ALSA]
2130
2131 snd-serial= [HW,ALSA]
2132
2133 snd-sgalaxy= [HW,ALSA]
2134
2135 snd-sonicvibes= [HW,ALSA]
2136
2137 snd-sun-amd7930=
2138 [HW,ALSA]
2139
2140 snd-sun-cs4231= [HW,ALSA]
2141
2142 snd-trident= [HW,ALSA]
2143
2144 snd-usb-audio= [HW,ALSA,USB]
2145
2146 snd-via82xx= [HW,ALSA]
2147
2148 snd-virmidi= [HW,ALSA]
2149
2150 snd-wavefront= [HW,ALSA]
2151
2152 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002153
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002154 softlockup_panic=
2155 [KNL] Should the soft-lockup detector generate panics.
2156
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2158 See Documentation/sonypi.txt
2159
2160 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002161 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002162
2163 spia_io_base= [HW,MTD]
2164 spia_fio_base=
2165 spia_pedr=
2166 spia_peddr=
2167
2168 sscape= [HW,OSS]
2169 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002170
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2172 See Documentation/scsi/st.txt.
2173
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 sti= [PARISC,HW]
2175 Format: <num>
2176 Set the STI (builtin display/keyboard on the HP-PARISC
2177 machines) console (graphic card) which should be used
2178 as the initial boot-console.
2179 See also comment in drivers/video/console/sticore.c.
2180
2181 sti_font= [HW]
2182 See comment in drivers/video/console/sticore.c.
2183
2184 stifb= [HW]
2185 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2186
Greg Banks42a7fc42007-03-06 01:42:23 -08002187 sunrpc.pool_mode=
2188 [NFS]
2189 Control how the NFS server code allocates CPUs to
2190 service thread pools. Depending on how many NICs
2191 you have and where their interrupts are bound, this
2192 option will affect which CPUs will do NFS serving.
2193 Note: this parameter cannot be changed while the
2194 NFS server is running.
2195
2196 auto the server chooses an appropriate mode
2197 automatically using heuristics
2198 global a single global pool contains all CPUs
2199 percpu one pool for each CPU
2200 pernode one pool for each NUMA node (equivalent
2201 to global on non-NUMA machines)
2202
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002204
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205 switches= [HW,M68k]
2206
2207 sym53c416= [HW,SCSI]
2208 See header of drivers/scsi/sym53c416.c.
2209
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002210 sysrq_always_enabled
2211 [KNL]
2212 Ignore sysrq setting - this boot parameter will
2213 neutralize any effect of /proc/sys/kernel/sysrq.
2214 Useful for debugging.
2215
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216 t128= [HW,SCSI]
2217 See header of drivers/scsi/t128.c.
2218
2219 tdfx= [HW,DRM]
2220
David Brownell77437fd2008-07-23 21:28:33 -07002221 test_suspend= [SUSPEND]
2222 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2223 standby suspend) as the system sleep state to briefly
2224 enter during system startup. The system is woken from
2225 this state using a wakeup-capable RTC alarm.
2226
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227 thash_entries= [KNL,NET]
2228 Set number of hash buckets for TCP connection
2229
Len Brownf8707ec2007-08-12 00:12:54 -04002230 thermal.act= [HW,ACPI]
2231 -1: disable all active trip points in all thermal zones
2232 <degrees C>: override all lowest active trip points
2233
Len Brownc52a7412007-08-14 15:49:32 -04002234 thermal.crt= [HW,ACPI]
2235 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002236 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002237
Len Brownf5487142007-08-12 00:12:44 -04002238 thermal.nocrt= [HW,ACPI]
2239 Set to disable actions on ACPI thermal zone
2240 critical and hot trip points.
2241
Len Brown72b33ef2007-08-12 00:12:17 -04002242 thermal.off= [HW,ACPI]
2243 1: disable ACPI thermal control
2244
Len Browna70cdc52007-08-12 00:12:35 -04002245 thermal.psv= [HW,ACPI]
2246 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002247 <degrees C>: override all passive trip points to this
2248 value
Len Browna70cdc52007-08-12 00:12:35 -04002249
Len Brown730ff342007-08-12 00:12:26 -04002250 thermal.tzp= [HW,ACPI]
2251 Specify global default ACPI thermal zone polling rate
2252 <deci-seconds>: poll all this frequency
2253 0: no polling (default)
2254
Linus Torvalds1da177e2005-04-16 15:20:36 -07002255 tmscsim= [HW,SCSI]
2256 See comment before function dc390_setup() in
2257 drivers/scsi/tmscsim.c.
2258
2259 tp720= [HW,PS2]
2260
2261 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002262 Format:
2263 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2264
Randy Dunlapa9913042005-10-23 12:57:11 -07002265 turbografx.map[2|3]= [HW,JOY]
2266 TurboGraFX parallel port interface
2267 Format:
2268 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269 See also Documentation/input/joystick-parport.txt
2270
2271 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2272 See header of drivers/scsi/u14-34f.c.
2273
2274 uart401= [HW,OSS]
2275 Format: <io>,<irq>
2276
2277 uart6850= [HW,OSS]
2278 Format: <io>,<irq>
2279
Alan Stern5f8364b2006-12-05 16:29:55 -05002280 uhci-hcd.ignore_oc=
2281 [USB] Ignore overcurrent events (default N).
2282 Some badly-designed motherboards generate lots of
2283 bogus events, for ports that aren't wired to
2284 anything. Set this parameter to avoid log spamming.
2285 Note that genuine overcurrent events won't be
2286 reported either.
2287
Simon Arlotte3a61b02008-07-19 23:32:54 +01002288 unknown_nmi_panic
2289 [X86-32,X86-64]
2290 Set unknown_nmi_panic=1 early on boot.
2291
Alan Sternb5e795f2007-02-20 15:00:53 -05002292 usbcore.autosuspend=
2293 [USB] The autosuspend time delay (in seconds) used
2294 for newly-detected USB devices (default 2). This
2295 is the time required before an idle device will be
2296 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002297 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002298
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002299 usbcore.usbfs_snoop=
2300 [USB] Set to log all usbfs traffic (default 0 = off).
2301
2302 usbcore.blinkenlights=
2303 [USB] Set to cycle leds on hubs (default 0 = off).
2304
2305 usbcore.old_scheme_first=
2306 [USB] Start with the old device initialization
2307 scheme (default 0 = off).
2308
2309 usbcore.use_both_schemes=
2310 [USB] Try the other device initialization scheme
2311 if the first one fails (default 1 = enabled).
2312
2313 usbcore.initial_descriptor_timeout=
2314 [USB] Specifies timeout for the initial 64-byte
2315 USB_REQ_GET_DESCRIPTOR request in milliseconds
2316 (default 5000 = 5.0 seconds).
2317
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318 usbhid.mousepoll=
2319 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002320
Paul Jackson200001e2008-06-25 05:44:46 -07002321 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2322 kernel's map of available physical RAM.
2323
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002324 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002325 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002326 vdso=1: enable VDSO (default)
2327 vdso=0: disable VDSO mapping
2328
Roland McGrathaf65d642008-01-30 13:30:43 +01002329 vdso32= [X86-32,X86-64]
2330 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2331 vdso32=1: enable 32-bit VDSO (default)
2332 vdso32=0: disable 32-bit VDSO mapping
2333
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002334 vector= [IA-64,SMP]
2335 vector=percpu: enable percpu vector domain
2336
Linus Torvalds1da177e2005-04-16 15:20:36 -07002337 video= [FB] Frame buffer configuration
2338 See Documentation/fb/modedb.txt.
2339
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002340 vga= [BOOT,X86-32] Select a particular video mode
Uwe Hermann71cced62008-10-20 09:32:21 -07002341 See Documentation/x86/i386/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002342 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002343 Use vga=ask for menu.
2344 This is actually a boot loader parameter; the value is
2345 passed to the kernel using a special protocol.
2346
Randy Dunlapa9913042005-10-23 12:57:11 -07002347 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 size of <nn>. This can be used to increase the
2349 minimum size (128MB on x86). It can also be used to
2350 decrease the size and leave more room for directly
2351 mapped kernel RAM.
2352
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002353 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2354 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002355
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002356 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2357 Format: <command>
2358
2359 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2360 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002361
Linus Torvalds1da177e2005-04-16 15:20:36 -07002362 waveartist= [HW,OSS]
2363 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002364
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365 wd33c93= [HW,SCSI]
2366 See header of drivers/scsi/wd33c93.c.
2367
2368 wd7000= [HW,SCSI]
2369 See header of drivers/scsi/wd7000.c.
2370
2371 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002372 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373
2374 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2375 xd_geo= See header of drivers/block/xd.c.
2376
2377 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002378 Format:
2379 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002380
Andi Kleena62eaf12006-02-16 23:41:58 +01002381 norandmaps Don't use address space randomization
2382 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2383
Randy Dunlapa9913042005-10-23 12:57:11 -07002384______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385
2386TODO:
2387
2388 Add documentation for ALSA options.
2389 Add more DRM drivers.