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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.
Steven Rostedtf38f1d22008-12-16 23:06:40 -050092 FTRACE Function tracing enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 TS Appropriate touchscreen support is enabled.
94 USB USB support is enabled.
95 USBHID USB Human Interface Device support is enabled.
96 V4L Video For Linux support is enabled.
97 VGA The VGA console has been enabled.
98 VT Virtual terminal support is enabled.
99 WDT Watchdog support is enabled.
100 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700101 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 X86-64 X86-64 architecture is enabled.
103 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700104 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200105 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
107In addition, the following text indicates that the option:
108
109 BUGS= Relates to possible processor bugs on the said processor.
110 KNL Is a kernel start-up parameter.
111 BOOT Is a boot loader parameter.
112
113Parameters denoted with BOOT are actually interpreted by the boot
114loader, and have no meaning to the kernel directly.
115Do not modify the syntax of boot loader parameters without extreme
Uwe Hermann71cced62008-10-20 09:32:21 -0700116need or coordination with <Documentation/x86/i386/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117
Karsten Weiss55588702007-02-13 13:26:21 +0100118There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700119See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100120
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
122a trailing = on the name of any parameter states that that parameter will
123be entered as an environment variable, whereas its absence indicates that
124it will appear as a kernel argument readable via /proc/cmdline by programs
125running once the system is up.
126
jens m. noedler9c4751f2006-09-29 02:00:27 -0700127The number of kernel parameters is not limited, but the length of the
128complete command line (parameters including spaces etc.) is limited to
129a fixed number of characters. This limit depends on the architecture
130and is between 256 and 4096 characters. It is defined in the file
131./include/asm/setup.h as COMMAND_LINE_SIZE.
132
133
Bernhard Walle03d926f2007-03-06 02:29:44 -0800134 acpi= [HW,ACPI,X86-64,i386]
135 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700136 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 force -- enable ACPI if default was off
138 off -- disable ACPI if default was on
139 noirq -- do not use ACPI for IRQ routing
140 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700141 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 strictly ACPI specification compliant.
143
Randy Dunlap53471122008-03-12 18:10:51 -0400144 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
Len Browna1fdcc02007-03-11 03:26:14 -0400146 acpi_apic_instance= [ACPI, IOAPIC]
147 Format: <int>
148 2: use 2nd APIC table, if available
149 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400150 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 acpi_sleep= [HW,ACPI] Sleep options
Shaohua Libdfe6b72008-07-23 21:28:41 -0700153 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
Pavel Machek23b168d2008-02-05 19:27:12 +0100154 See Documentation/power/video.txt for s3_bios and s3_mode.
155 s3_beep is for debugging; it makes the PC's speaker beep
156 as soon as the kernel's real-mode entry point is called.
Shaohua Libdfe6b72008-07-23 21:28:41 -0700157 s4_nohwsig prevents ACPI hardware signature from being
158 used during resume from hibernation.
Rafael J. Wysockid8f3de02008-06-12 23:24:06 +0200159 old_ordering causes the ACPI 1.0 ordering of the _PTS
160 control method, wrt putting devices into low power
161 states, to be enforced (the ACPI 2.0 ordering of _PTS is
162 used by default).
Randy Dunlapa9913042005-10-23 12:57:11 -0700163
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700165 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
Randy Dunlapa9913042005-10-23 12:57:11 -0700167 acpi_irq_balance [HW,ACPI]
168 ACPI will balance active IRQs
169 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
Randy Dunlapa9913042005-10-23 12:57:11 -0700171 acpi_irq_nobalance [HW,ACPI]
172 ACPI will not move active IRQs (default)
173 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
Randy Dunlapa9913042005-10-23 12:57:11 -0700175 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
176 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 Format: <irq>,<irq>...
178
Randy Dunlapa9913042005-10-23 12:57:11 -0700179 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 Format: <irq>,<irq>...
181
Len Brown67effe82007-07-26 00:50:06 -0400182 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
183
Len Browna1f9e652006-01-25 23:47:36 -0500184 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
185 Format: To spoof as Windows 98: ="Microsoft Windows"
186
Len Brownae00d812007-05-29 18:43:33 -0400187 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
188 acpi_osi="string1" # add string1 -- only one string
189 acpi_osi="!string2" # remove built-in string2
190 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191
192 acpi_serialize [HW,ACPI] force serialization of AML methods
193
194 acpi_skip_timer_override [HW,ACPI]
195 Recognize and ignore IRQ0/pin2 Interrupt Override.
196 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100197 acpi_use_timer_override [HW,ACPI}
198 Use timer override. For some broken Nvidia NF5 boards
199 that require a timer override, but don't have
200 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200202 acpi_backlight= [HW,ACPI]
203 acpi_backlight=vendor
204 acpi_backlight=video
205 If set to vendor, prefer vendor specific driver
206 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
207 of the ACPI video.ko driver.
208
209 acpi_display_output= [HW,ACPI]
210 acpi_display_output=vendor
211 acpi_display_output=video
212 See above.
213
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700214 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
215 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700217 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
218 debug output. Bits in debug_layer correspond to a
219 _COMPONENT in an ACPI source file, e.g.,
220 #define _COMPONENT ACPI_PCI_COMPONENT
221 Bits in debug_level correspond to a level in
222 ACPI_DEBUG_PRINT statements, e.g.,
223 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
224 See Documentation/acpi/debug.txt for more information
225 about debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700227 Enable AML "Debug" output, i.e., stores to the Debug
228 object while interpreting AML:
229 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
230 Enable PCI/PCI interrupt routing info messages:
231 acpi.debug_layer=0x400000 acpi.debug_level=0x4
232 Enable all messages related to ACPI hardware:
233 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200234
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700235 Some values produce so much output that the system is
236 unusable. The "log_buf_len" parameter may be useful
237 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800238
Zhao Yakuif5adfaa2008-08-11 14:57:50 +0800239 acpi.power_nocheck= [HW,ACPI]
240 Format: 1/0 enable/disable the check of power state.
241 On some bogus BIOS the _PSC object/_STA object of
242 power resource can't return the correct device power
243 state. In such case it is unneccessary to check its
244 power state again in power transition.
245 1 : disable the power state check
246
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700247 acpi_pm_good [X86-32,X86-64]
john stultz5d0cf412006-06-26 00:25:12 -0700248 Override the pmtimer bug detection: force the kernel
249 to assume that this machine's pmtimer latches its value
250 and always returns good values.
251
Chuck Ebbertc99c1082007-07-27 10:46:20 +1000252 agp= [AGP]
253 { off | try_unsupported }
254 off: disable AGP support
255 try_unsupported: try to drive unsupported chipsets
256 (may crash computer or cause data corruption)
257
Chuck Ebbert66759a02005-09-12 18:49:25 +0200258 enable_timer_pin_1 [i386,x86-64]
259 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700260 Can be useful to work around chipset bugs
261 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200262 The kernel tries to set a reasonable default.
263
264 disable_timer_pin_1 [i386,x86-64]
265 Disable PIN 1 of APIC timer
266 Can be useful to work around chipset bugs.
267
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 ad1848= [HW,OSS]
269 Format: <io>,<irq>,<dma>,<dma2>,<type>
270
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 advansys= [HW,SCSI]
272 See header of drivers/scsi/advansys.c.
273
274 advwdt= [HW,WDT] Advantech WDT
275 Format: <iostart>,<iostop>
276
277 aedsp16= [HW,OSS] Audio Excel DSP 16
278 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
279 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700280
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 aha152x= [HW,SCSI]
282 See Documentation/scsi/aha152x.txt.
283
284 aha1542= [HW,SCSI]
285 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
286
287 aic7xxx= [HW,SCSI]
288 See Documentation/scsi/aic7xxx.txt.
289
290 aic79xx= [HW,SCSI]
291 See Documentation/scsi/aic79xx.txt.
292
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200293 amd_iommu= [HW,X86-84]
294 Pass parameters to the AMD IOMMU driver in the system.
295 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200296 isolate - enable device isolation (each device, as far
297 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100298 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100299 share - put every device behind one IOMMU into the
300 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900301 fullflush - enable flushing of IO/TLB entries when
302 they are unmapped. Otherwise they are
303 flushed before they will be reused, which
304 is a lot of faster
305
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200306 amd_iommu_size= [HW,X86-64]
307 Define the size of the aperture for the AMD IOMMU
308 driver. Possible values are:
309 '32M', '64M' (default), '128M', '256M', '512M', '1G'
310
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 amijoy.map= [HW,JOY] Amiga joystick support
312 Map of devices attached to JOY0DAT and JOY1DAT
313 Format: <a>,<b>
314 See also Documentation/kernel/input/joystick.txt
315
316 analog.map= [HW,JOY] Analog joystick and gamepad support
317 Specifies type or capabilities of an analog joystick
318 connected to one of 16 gameports
319 Format: <type1>,<type2>,..<type16>
320
Randy Dunlapa9913042005-10-23 12:57:11 -0700321 apc= [HW,SPARC]
322 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 Format: noidle
324 Disable APC CPU standby support. SPARCstation-Fox does
325 not play well with APC CPU idle - disable it if you have
326 APC and your system crashes randomly.
327
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700328 apic= [APIC,i386] Advanced Programmable Interrupt Controller
329 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 Format: { quiet (default) | verbose | debug }
331 Change the amount of debugging information output
332 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700333
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700335 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
338 Format: <io>,<irq>,<nodeID>
339
340 ataflop= [HW,M68k]
341
342 atarimouse= [HW,MOUSE] Atari Mouse
343
344 atascsi= [HW,SCSI] Atari SCSI
345
346 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
347 EzKey and similar keyboards
348
349 atkbd.reset= [HW] Reset keyboard during initialization
350
Randy Dunlapa9913042005-10-23 12:57:11 -0700351 atkbd.set= [HW] Select keyboard code set
352 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353
354 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
355 keyboards
356
357 atkbd.softraw= [HW] Choose between synthetic and real raw mode
358 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700359
360 atkbd.softrepeat= [HW]
361 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362
363 autotest [IA64]
364
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 baycom_epp= [HW,AX25]
366 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
369 Format: <io>,<mode>
370 See header of drivers/net/hamradio/baycom_par.c.
371
Randy Dunlapa9913042005-10-23 12:57:11 -0700372 baycom_ser_fdx= [HW,AX25]
373 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 Format: <io>,<irq>,<mode>[,<baud>]
375 See header of drivers/net/hamradio/baycom_ser_fdx.c.
376
Randy Dunlapa9913042005-10-23 12:57:11 -0700377 baycom_ser_hdx= [HW,AX25]
378 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 Format: <io>,<irq>,<mode>
380 See header of drivers/net/hamradio/baycom_ser_hdx.c.
381
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700382 boot_delay= Milliseconds to delay each printk during boot.
383 Values larger than 10 seconds (10000) are changed to
384 no delay (0).
385 Format: integer
386
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700387 bootmem_debug [KNL] Enable bootmem allocator debug messages.
388
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700390 bttv.radio= Most important insmod options are available as
391 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
393 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
394
395 BusLogic= [HW,SCSI]
396 See drivers/scsi/BusLogic.c, comment before function
397 BusLogic_ParseDriverOptions().
398
399 c101= [NET] Moxa C101 synchronous serial card
400
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700401 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 Sometimes CPU hardware bugs make them report the cache
403 size incorrectly. The kernel will attempt work arounds
404 to fix known problems, but for some CPUs it is not
405 possible to determine what the correct size should be.
406 This option provides an override for these situations.
407
Ahmed S. Darwish076c54c2008-03-06 18:09:10 +0200408 security= [SECURITY] Choose a security module to enable at boot.
409 If this boot parameter is not specified, only the first
410 security module asking for security registration will be
411 loaded. An invalid security module name will be treated
412 as if no module has been chosen.
413
James Morris20510f22007-10-16 23:31:32 -0700414 capability.disable=
415 [SECURITY] Disable capabilities. This would normally
416 be used only if an alternative security model is to be
417 configured. Potentially dangerous and should only be
418 used if you are entirely sure of the consequences.
419
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100420 ccw_timeout_log [S390]
421 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422
Paul Menage8bab8dd2008-04-04 14:29:57 -0700423 cgroup_disable= [KNL] Disable a particular controller
424 Format: {name of the controller(s) to disable}
425 {Currently supported controllers - "memory"}
426
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 checkreqprot [SELINUX] Set initial checkreqprot flag value.
428 Format: { "0" | "1" }
429 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700430 0 -- check protection applied by kernel (includes
431 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 1 -- check protection requested by application.
433 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700434 Value can be changed at runtime via
435 /selinux/checkreqprot.
436
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100437 cio_ignore= [S390]
438 See Documentation/s390/CommonIO for details.
439
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700440 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700441 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200442 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700443 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200444 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 Format: { pit | tsc | cyclone | pmtmr }
446
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700447 clocksource= [GENERIC_TIME] Override the default clocksource
448 Format: <string>
449 Override the default clocksource and use the clocksource
450 with the name specified.
451 Some clocksource names to choose from, depending on
452 the platform:
453 [all] jiffies (this is the base, fallback clocksource)
454 [ACPI] acpi_pm
455 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
456 pxa_timer,timer3,32k_counter,timer0_1
457 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700458 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700459 scx200_hrt on Geode; cyclone on IBM x440
460 [MIPS] MIPS
461 [PARISC] cr16
462 [S390] tod
463 [SH] SuperH
464 [SPARC64] tick
465 [X86-64] hpet,tsc
466
Andi Kleenac72e782008-01-30 13:33:21 +0100467 clearcpuid=BITNUM [X86]
468 Disable CPUID feature X for the kernel. See
469 include/asm-x86/cpufeature.h for the valid bit numbers.
470 Note the Linux specific bits are not necessarily
471 stable over kernel options, but the vendor specific
472 ones should be.
473 Also note that user programs calling CPUID directly
474 or using the feature without checking anything
475 will still see it. This just prevents it from
476 being used by the kernel or shown in /proc/cpuinfo.
477 Also note the kernel might malfunction if you disable
478 some critical bits.
479
Arjan van de Vena25bd942008-01-30 13:33:08 +0100480 code_bytes [IA32/X86_64] How many bytes of object code to print
481 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100482 Range: 0 - 8192
483 Default: 64
484
Thomas Gleixnerb17530b2007-10-19 20:35:02 +0200485 hpet= [X86-32,HPET] option to control HPET usage
486 Format: { enable (default) | disable | force }
487 disable: disable HPET and use PIT instead
Carlos Corbachod79a5f82007-10-19 18:51:27 +0100488 force: allow force enabled of undocumented chips (ICH4,
489 VIA, nVidia)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700492 Format:
493 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494
495 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
496 Format: <io>[,<irq>]
497
Randy Dunlapa9913042005-10-23 12:57:11 -0700498 com90xx= [HW,NET]
499 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 Format: <io>[,<irq>[,<memstart>]]
501
502 condev= [HW,S390] console device
503 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700504
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505 console= [KNL] Output console device and options.
506
507 tty<n> Use the virtual console device <n>.
508
509 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800510 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800512 the form "bbbbpnf", where "bbbb" is the baud rate,
513 "p" is parity ("n", "o", or "e"), "n" is number of
514 bits, and "f" is flow control ("r" for RTS or
515 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800517 See Documentation/serial-console.txt for more
518 information. See
519 Documentation/networking/netconsole.txt for an
520 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address,
526 switching to the matching ttyS device later. The
527 options are the same as for ttyS, above.
528
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700529 If the device connected to the port is not a TTY but a braille
530 device, prepend "brl," before the device type, for instance
531 console=brl,ttyS0
532 For now, only VisioBraille is supported.
533
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700534 earlycon= [KNL] Output early console device and options.
535 uart[8250],io,<addr>[,options]
536 uart[8250],mmio,<addr>[,options]
537 Start an early, polled-mode console on the 8250/16550
538 UART at the specified I/O port or MMIO address.
539 The options are the same as for ttyS, above.
540
Andres Salomon8f4ce8c2007-10-18 03:04:50 -0700541 no_console_suspend
542 [HW] Never suspend the console
543 Disable suspending of consoles during suspend and
544 hibernate operations. Once disabled, debugging
545 messages can reach various consoles while the rest
546 of the system is being put to sleep (ie, while
547 debugging driver suspend/resume hooks). This may
548 not work reliably with all consoles, but is known
549 to work with serial and VGA consoles.
550
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700552 Format:
553 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700555 crashkernel=nn[KMG]@ss[KMG]
556 [KNL] Reserve a chunk of physical memory to
557 hold a kernel to switch to with kexec on panic.
558
Bernhard Wallefb391592007-10-18 23:41:02 -0700559 crashkernel=range1:size1[,range2:size2,...][@offset]
560 [KNL] Same as above, but depends on the memory
561 in the running system. The syntax of range is
562 start-[end] where start and end are both
563 a memory unit (amount[KMG]). See also
564 Documentation/kdump/kdump.txt for a example.
565
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 cs4232= [HW,OSS]
567 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
568
569 cs89x0_dma= [HW,NET]
570 Format: <dma>
571
572 cs89x0_media= [HW,NET]
573 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700574
Randy Dunlapa9913042005-10-23 12:57:11 -0700575 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 See header of drivers/s390/block/dasd_devmap.c.
577
578 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
579 (one device per port)
580 Format: <port#>,<type>
581 See also Documentation/input/joystick-parport.txt
582
583 debug [KNL] Enable kernel debugging (events log level).
584
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700585 debug_locks_verbose=
586 [KNL] verbose self-tests
587 Format=<0|1>
588 Print debugging info while doing the locking API
589 self-tests.
590 We default to 0 (no extra messages), setting it to
591 1 will print _a lot_ more information - normally
592 only useful to kernel developers.
593
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700594 debug_objects [KNL] Enable object debugging
595
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200596 debugpat [X86] Enable PAT debugging
597
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200598 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 Format: <area>[,<node>]
600 See also Documentation/networking/decnet.txt.
601
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000602 vt.default_blu= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700603 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
604 Change the default blue palette of the console.
605 This is a 16-member array composed of values
606 ranging from 0-255.
607
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000608 vt.default_grn= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700609 Format: <green0>,<green1>,<green2>,...,<green15>
610 Change the default green palette of the console.
611 This is a 16-member array composed of values
612 ranging from 0-255.
613
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000614 vt.default_red= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700615 Format: <red0>,<red1>,<red2>,...,<red15>
616 Change the default red palette of the console.
617 This is a 16-member array composed of values
618 ranging from 0-255.
619
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000620 vt.default_utf8=
621 [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700622 Format=<0|1>
623 Set system-wide default UTF-8 mode for all tty's.
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000624 Default is 1, i.e. UTF-8 mode is enabled for all
625 newly opened terminals.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700626
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 dhash_entries= [KNL]
628 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700629
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 digi= [HW,SERIAL]
631 IO parameters + enable/disable command.
632
633 digiepca= [HW,SERIAL]
634 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000635 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636
Yinghai Lu95ffa242008-04-29 03:52:33 -0700637 disable_mtrr_cleanup [X86]
638 enable_mtrr_cleanup [X86]
639 The kernel tries to adjust MTRR layout from continuous
640 to discrete, to make X server driver able to add WB
641 entry later. This parameter enables/disables that.
642
643 mtrr_chunk_size=nn[KMG] [X86]
644 used for mtrr cleanup. It is largest continous chunk
645 that could hold holes aka. UC entries.
646
647 mtrr_gran_size=nn[KMG] [X86]
Yinghai Lu12031a62008-05-02 02:40:22 -0700648 Used for mtrr cleanup. It is granularity of mtrr block.
649 Default is 1.
650 Large value could prevent small alignment from
651 using up MTRRs.
652
653 mtrr_spare_reg_nr=n [X86]
654 Format: <integer>
655 Range: 0,7 : spare reg number
656 Default : 1
657 Used for mtrr cleanup. It is spare mtrr entries number.
658 Set to 2 or more if your graphical card needs more.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700659
Yinghai Lu093af8d2008-01-30 13:33:32 +0100660 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100661 By default the kernel will trim any uncacheable
662 memory out of your available memory pool based on
663 MTRR settings. This parameter disables that behavior,
664 possibly causing your machine to run very slowly.
665
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 dmasound= [HW,OSS] Sound subsystem buffers
667
668 dscc4.setup= [NET]
669
670 dtc3181e= [HW,SCSI]
671
Robin Getz0ae53642007-10-09 17:24:49 +0800672 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 earlyprintk=vga
674 earlyprintk=serial[,ttySn[,baudrate]]
Yinghai Lu5c059172008-07-24 17:29:40 -0700675 earlyprintk=dbgp
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676
Randy Dunlapa9913042005-10-23 12:57:11 -0700677 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 takes over.
679
Yinghai Lu5c059172008-07-24 17:29:40 -0700680 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681
682 Currently only ttyS0 and ttyS1 are supported.
683
684 Interaction with the standard serial driver is not
685 very good.
686
687 The VGA output is eventually overwritten by the real
688 console.
689
690 eata= [HW,SCSI]
691
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700693 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 eisa_irq_edge= [PARISC,HW]
696 See header of drivers/parisc/eisa.c.
697
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700698 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700700 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701
702 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800703 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700704 See Documentation/block/as-iosched.txt and
705 Documentation/block/deadline-iosched.txt for details.
706
Simon Hormane515a0d2008-10-18 20:28:27 -0700707 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700708 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800709 image elf header. Generally kexec loader will
710 pass this option to capture kernel.
711 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712
713 enforcing [SELINUX] Set initial enforcing status.
714 Format: {"0" | "1"}
715 See security/selinux/Kconfig help text.
716 0 -- permissive (log only, no denials).
717 1 -- enforcing (deny and log).
718 Default value is 0.
719 Value can be changed at runtime via /selinux/enforce.
720
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 es1371= [HW,OSS]
722 Format: <spdif>,[<nomix>,[<amplifier>]]
723 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700724
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 ether= [HW,NET] Ethernet cards parameters
726 This option is obsoleted by the "netdev=" option, which
727 has equivalent usage. See its documentation for details.
728
729 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
730 Format: <io>[,<irq>]
731
Akinobu Mitade1ba092006-12-08 02:39:42 -0800732 failslab=
733 fail_page_alloc=
734 fail_make_request=[KNL]
735 General fault injection mechanism.
736 Format: <interval>,<probability>,<space>,<times>
737 See also /Documentation/fault-injection/.
738
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 fd_mcs= [HW,SCSI]
740 See header of drivers/scsi/fd_mcs.c.
741
742 fdomain= [HW,SCSI]
743 See header of drivers/scsi/fdomain.c.
744
745 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000746 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747
Alex Chiangf13ae302008-05-08 14:03:23 -0600748 force_pal_cache_flush
749 [IA-64] Avoid check_sal_cache_flush which may hang on
750 buggy SAL_CACHE_FLUSH implementations. Using this
751 parameter will force ia64_sal_cache_flush to call
752 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
753
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100754 ftrace=[tracer]
755 [ftrace] will set and start the specified tracer
756 as early as possible in order to facilitate early
757 boot debugging.
758
759 ftrace_dump_on_oops
760 [ftrace] will dump the trace buffers on oops.
761
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 gamecon.map[2|3]=
763 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
764 support via parallel port (up to 5 devices per port)
765 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
766 See also Documentation/input/joystick-parport.txt
767
768 gamma= [HW,DRM]
769
Yinghai Luaaf23042008-01-30 13:33:09 +0100770 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
771 Format: off | on
772 default: on
773
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 gdth= [HW,SCSI]
775 See header of drivers/scsi/gdth.c.
776
777 gpt [EFI] Forces disk with valid GPT signature but
778 invalid Protective MBR to be treated as GPT.
779
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 gvp11= [HW,SCSI]
781
782 hashdist= [KNL,NUMA] Large hashes allocated during boot
783 are distributed across NUMA nodes. Defaults on
784 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700785 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786
787 hcl= [IA-64] SGI's Hardware Graph compatibility layer
788
789 hd= [EIDE] (E)IDE hard drive subsystem geometry
790 Format: <cyl>,<head>,<sect>
791
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
793 size of <nn>. This works even on boxes that have no
794 highmem otherwise. This also works to reduce highmem
795 size on bigger boxes.
796
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800797 highres= [KNL] Enable/disable high resolution timer mode.
798 Valid parameters: "on", "off"
799 Default: "on"
800
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 hisax= [HW,ISDN]
802 See Documentation/isdn/README.HiSax.
803
Andi Kleenb4718e62008-07-23 21:27:51 -0700804 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
805 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700806 On x86-64 and powerpc, this option can be specified
807 multiple times interleaved with hugepages= to reserve
808 huge pages of different sizes. Valid pages sizes on
809 x86-64 are 2M (when the CPU supports "pse") and 1G
810 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700811 Note that 1GB pages can only be allocated at boot time
812 using hugepages= and not freed afterwards.
Nick Piggine11bfbf2008-07-23 21:27:52 -0700813 default_hugepagesz=
814 [same as hugepagesz=] The size of the default
815 HugeTLB page size. This is the size represented by
816 the legacy /proc/ hugepages APIs, used for SHM, and
817 default size when mounting hugetlbfs filesystems.
818 Defaults to the default architecture's huge page size
819 if not specified.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820
Paul Mundt6902aa82008-09-21 17:14:42 +0900821 hlt [BUGS=ARM,SH]
822
Jiri Kosina36d95732008-10-06 02:51:09 -0400823 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200825 i8042.dumbkbd [HW] Pretend that controller can only read data from
826 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 (Don't attempt to blink the leds)
828 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500829 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400830 i8042.noloop [HW] Disable the AUX Loopback command while probing
831 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 i8042.nomux [HW] Don't check presence of an active multiplexing
833 controller
834 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
835 controllers
836 i8042.panicblink=
837 [HW] Frequency with which keyboard LEDs should blink
838 when kernel panics (default is 0.5 sec)
839 i8042.reset [HW] Reset the controller during init and cleanup
840 i8042.unlock [HW] Unlock (ignore) the keylock
841
842 i810= [HW,DRM]
843
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700844 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
845 indicates that the driver is running on unsupported
846 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
848 does not match list of supported models.
849 i8k.power_status
850 [HW] Report power status in /proc/i8k
851 (disabled by default)
852 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
853 capability is set.
854
855 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
856 See Documentation/mca.txt.
857
858 icn= [HW,ISDN]
859 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
860
861 ide= [HW] (E)IDE subsystem
Greg Kroah-Hartmana594eeb2008-04-18 00:46:20 +0200862 Format: ide=nodma or ide=doubler
Randy Dunlap1c10e932008-03-07 21:53:50 +0100863 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100866 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867
Andi Kleenf039b752007-05-02 19:27:12 +0200868 idle= [X86]
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800869 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Andi Kleenf039b752007-05-02 19:27:12 +0200870 Poll forces a polling idle loop that can slightly improves the performance
871 of waking up a idle CPU, but will use a lot of power and make the system
872 run hot. Not recommended.
873 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
874 to not use it because it doesn't save as much power as a normal idle
875 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
876 as idle=poll.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800877 idle=halt. Halt is forced to be used for CPU idle.
878 In such case C2/C3 won't be used again.
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800879 idle=nomwait. Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700880
Denis Cheng594765a2008-02-06 02:57:49 +0100881 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
882 Claim all unknown PCI IDE storage controllers.
883
Ingo Molnar792908222006-12-06 20:40:51 -0800884 ignore_loglevel [KNL]
885 Ignore loglevel setting - this will print /all/
886 kernel messages to the console. Useful for debugging.
887
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888 ihash_entries= [KNL]
889 Set number of hash buckets for inode cache.
890
891 in2000= [HW,SCSI]
892 See header of drivers/scsi/in2000.c.
893
894 init= [KNL]
895 Format: <full_path>
896 Run specified binary instead of /sbin/init as init
897 process.
898
899 initcall_debug [KNL] Trace initcalls as they are executed. Useful
900 for working out where the kernel is dying during
901 startup.
902
903 initrd= [BOOT] Specify the location of the initial ramdisk
904
905 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
906 Format: <irq>
907
908 inttest= [IA64]
909
Pavel Machekb552da82008-03-19 15:58:11 +0100910 iommu= [x86]
911 off
912 force
913 noforce
914 biomerge
915 panic
916 nopanic
917 merge
918 nomerge
919 forcesac
920 soft
921
922
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700923 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
924 off
925 Disable intel iommu driver.
926 igfx_off [Default Off]
927 By default, gfx is mapped as normal device. If a gfx
928 device has a dedicated DMAR unit, the DMAR unit is
929 bypassed by not enabling DMAR with this option. In
930 this case, gfx device will use physical address for
931 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700932 forcedac [x86_64]
933 With this option iommu will not optimize to look
934 for io virtual address below 32 bit forcing dual
935 address cycle on pci bus for cards supporting greater
936 than 32 bit addressing. The default is to look
937 for translation below 32 bit and if not available
938 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800939 strict [Default Off]
940 With this option on every unmap_single operation will
941 result in a hardware IOTLB flush operation as opposed
942 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700943
Rene Hermanb02aae92008-01-30 13:30:05 +0100944 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100945 0x80
946 Standard port 0x80 based delay
947 0xed
948 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100949 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100950 Simple two microseconds delay
951 none
952 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100953
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 io7= [HW] IO7 for Marvel based alpha systems
955 See comment before marvel_specify_io7 in
956 arch/alpha/kernel/core_marvel.c.
957
958 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400959 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960
961 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700962 See comment before ip2_setup() in
963 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964
965 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
966 See header of drivers/scsi/ips.c.
967
Simon Horman72c4a132006-09-13 19:57:18 -0700968 ports= [IP_VS_FTP] IPVS ftp helper module
969 Default is 21.
970 Up to 8 (IP_VS_APP_MAX_PORTS) ports
971 may be specified.
972 Format: <port>,<port>....
973
Alan Cox200803d2005-06-28 20:45:18 -0700974 irqfixup [HW]
975 When an interrupt is not handled search all handlers
976 for it. Intended to get systems with badly broken
977 firmware running.
978
979 irqpoll [HW]
980 When an interrupt is not handled search all handlers
981 for it. Also check all handlers each timer
982 interrupt. Intended to get systems with badly broken
983 firmware running.
984
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700986 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987
988 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800989 Format:
990 <cpu number>,...,<cpu number>
991 or
Li Zefanb225d442008-11-06 12:53:39 -0800992 <cpu number>-<cpu number>
993 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -0800994 or a mixture
995 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -0800996
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 This option can be used to specify one or more CPUs
998 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -0800999 algorithms. You can move a process onto or off an
1000 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 <cpu number> begins at 0 and the maximum value is
1002 "number of CPUs in system - 1".
1003
1004 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001005 alternative -- manually setting the CPU mask of all
1006 tasks in the system -- can cause problems and
1007 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008
Randy Dunlapa9913042005-10-23 12:57:11 -07001009 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010
1011 js= [HW,JOY] Analog joystick
1012 See Documentation/input/joystick.txt.
1013
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001014 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001015 specifies the amount of memory usable by the kernel
1016 for non-movable allocations. The requested amount is
1017 spread evenly throughout all nodes in the system. The
1018 remaining memory in each node is used for Movable
1019 pages. In the event, a node is too small to have both
1020 kernelcore and Movable pages, kernelcore pages will
1021 take priority and other nodes will have a larger number
1022 of kernelcore pages. The Movable zone is used for the
1023 allocation of pages that may be reclaimed or moved
1024 by the page migration subsystem. This means that
1025 HugeTLB pages may not be allocated from this zone.
1026 Note that allocations like PTEs-from-HighMem still
1027 use the HighMem zone if it exists, and the Normal
1028 zone if it does not.
1029
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001030 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efef2007-07-17 04:03:15 -07001031 is similar to kernelcore except it specifies the
1032 amount of memory used for migratable allocations.
1033 If both kernelcore and movablecore is specified,
1034 then kernelcore will be at *least* the specified
1035 value but may be more. If movablecore on its own
1036 is specified, the administrator must be careful
1037 that the amount of memory usable for all allocations
1038 is not too small.
1039
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 keepinitrd [HW,ARM]
1041
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001042 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 in oops dumps.
1044
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001045 kgdboc= [HW] kgdb over consoles.
1046 Requires a tty driver that supports console polling.
1047 (only serial suported for now)
1048 Format: <serial_device>[,baud]
1049
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001050 kmac= [MIPS] korina ethernet MAC address.
1051 Configure the RouterBoard 532 series on-chip
1052 Ethernet adapter MAC address.
1053
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054 l2cr= [PPC]
1055
Robert Brosea78bfbf2008-03-29 07:20:23 +11001056 l3cr= [PPC]
1057
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001058 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001059 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001061 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001062 C2 power state.
1063
FD Camifcb71f62008-01-06 19:08:56 +01001064 libata.dma= [LIBATA] DMA control
1065 libata.dma=0 Disable all PATA and SATA DMA
1066 libata.dma=1 PATA and SATA Disk DMA only
1067 libata.dma=2 ATAPI (CDROM) DMA only
1068 libata.dma=4 Compact Flash DMA only
1069 Combinations also work, so libata.dma=3 enables DMA
1070 for disks and CDROMs, but not CFs.
1071
Dave Jones78e70c22007-09-27 11:50:13 -04001072 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1073 when set.
1074 Format: <int>
1075
Tejun Heo33267322008-02-13 09:15:09 +09001076 libata.force= [LIBATA] Force configurations. The format is comma
1077 separated list of "[ID:]VAL" where ID is
1078 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1079 matching port, link or device. Basically, it matches
1080 the ATA ID string printed on console by libata. If
1081 the whole ID part is omitted, the last PORT and DEVICE
1082 values are used. If ID hasn't been specified yet, the
1083 configuration applies to all ports, links and devices.
1084
1085 If only DEVICE is omitted, the parameter applies to
1086 the port and all links and devices behind it. DEVICE
1087 number of 0 either selects the first device or the
1088 first fan-out link behind PMP device. It does not
1089 select the host link. DEVICE number of 15 selects the
1090 host link and device attached to it.
1091
1092 The VAL specifies the configuration to force. As long
1093 as there's no ambiguity shortcut notation is allowed.
1094 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1095 The following configurations can be forced.
1096
1097 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1098 Any ID with matching PORT is used.
1099
1100 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1101
1102 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1103 udma[/][16,25,33,44,66,100,133] notation is also
1104 allowed.
1105
1106 * [no]ncq: Turn on or off NCQ.
1107
Tejun Heo05944bd2008-08-13 20:19:09 +09001108 * nohrst, nosrst, norst: suppress hard, soft
1109 and both resets.
1110
Tejun Heo33267322008-02-13 09:15:09 +09001111 If there are multiple matching configurations changing
1112 the same attribute, the last one is used.
1113
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001115 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001117 lockd.nlm_grace_period=P [NFS] Assign grace period.
1118 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001120 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1121 Format: <integer>
1122
1123 lockd.nlm_timeout=T [NFS] Assign timeout value.
1124 Format: <integer>
1125
1126 lockd.nlm_udpport=M [NFS] Assign UDP port.
1127 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128
1129 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1130 Format: <irq>
1131
1132 loglevel= All Kernel Messages with a loglevel smaller than the
1133 console loglevel will be printed to the console. It can
1134 also be changed with klogd or other programs. The
1135 loglevels are defined as follows:
1136
1137 0 (KERN_EMERG) system is unusable
1138 1 (KERN_ALERT) action must be taken immediately
1139 2 (KERN_CRIT) critical conditions
1140 3 (KERN_ERR) error conditions
1141 4 (KERN_WARNING) warning conditions
1142 5 (KERN_NOTICE) normal but significant condition
1143 6 (KERN_INFO) informational
1144 7 (KERN_DEBUG) debug-level messages
1145
1146 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001147 Format: { n | nk | nM }
1148 n must be a power of two. The default size
1149 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150
Randy Dunlapaccaa242007-10-16 01:29:37 -07001151 logo.nologo [FB] Disables display of the built-in Linux logo.
1152 This may be used to provide more screen space for
1153 kernel log messages and is useful when debugging
1154 kernel boot problems.
1155
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156 lp=0 [LP] Specify parallel ports to use, e.g,
1157 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1158 lp=reset first parallel port). 'lp=0' disables the
1159 lp=auto printer driver. 'lp=reset' (which can be
1160 specified in addition to the ports) causes
1161 attached printers to be reset. Using
1162 lp=port1,port2,... specifies the parallel ports
1163 to associate lp devices with, starting with
1164 lp0. A port specification may be 'none' to skip
1165 that lp device, or a parport name such as
1166 'parport0'. Specifying 'lp=auto' instead of a
1167 port specification list means that device IDs
1168 from each port should be examined, to see if
1169 an IEEE 1284-compliant printer is attached; if
1170 so, the driver will manage that printer.
1171 See also header of drivers/char/lp.c.
1172
1173 lpj=n [KNL]
1174 Sets loops_per_jiffy to given constant, thus avoiding
1175 time-consuming boot-time autodetection (up to 250 ms per
1176 CPU). 0 enables autodetection (default). To determine
1177 the correct value for your kernel, boot with normal
1178 autodetection and see what value is printed. Note that
1179 on SMP systems the preset will be applied to all CPUs,
1180 which is likely to cause problems if your CPUs need
1181 significantly divergent settings. An incorrect value
1182 will cause delays in the kernel to be wrong, leading to
1183 unpredictable I/O errors and other breakage. Although
1184 unlikely, in the extreme case this might damage your
1185 hardware.
1186
1187 ltpc= [NET]
1188 Format: <io>,<irq>,<dma>
1189
Randy Dunlapa9913042005-10-23 12:57:11 -07001190 mac5380= [HW,SCSI] Format:
1191 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192
Randy Dunlapa9913042005-10-23 12:57:11 -07001193 machvec= [IA64] Force the use of a particular machine-vector
1194 (machvec) in a generic kernel.
1195 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196
Randy Dunlapa9913042005-10-23 12:57:11 -07001197 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 be mounted
1199 Format: <1-256>
1200
1201 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001202 should make use of. maxcpus=n : n >= 0 limits the
1203 kernel to using 'n' processors. n=0 is a special case,
1204 it is equivalent to "nosmp", which also disables
1205 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
Randy Dunlap1c207f952008-11-19 15:36:16 -08001207 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1208 or equal to this physical address is ignored.
Bob Picco2b2c3752005-06-29 18:00:00 -07001209
Randy Dunlapa9913042005-10-23 12:57:11 -07001210 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211 Should be between 1 and 2^32-1.
1212
1213 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001214 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 Should be between 1 and 16384.
1216
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 mcatest= [IA-64]
1218
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001219 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220
Uwe Hermann71cced62008-10-20 09:32:21 -07001221 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001222
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223 md= [HW] RAID subsystems devices and level
1224 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001225
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 mdacon= [MDA]
1227 Format: <first>,<last>
1228 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001229
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1231 Amount of memory to be used when the kernel is not able
1232 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001233 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234 address space collisions. Without memmap= PCI devices
1235 could be placed at addresses belonging to unused RAM.
1236
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001237 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 memory.
1239
Paul Mundt6902aa82008-09-21 17:14:42 +09001240 memchunk=nn[KMG]
1241 [KNL,SH] Allow user to override the default size for
1242 per-device physically contiguous DMA buffers.
1243
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001244 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245 E820 memory map, as specified by the user.
1246 Such memmap=exactmap lines can be constructed based on
1247 BIOS output or other requirements. See the memmap=nn@ss
1248 option description.
1249
1250 memmap=nn[KMG]@ss[KMG]
1251 [KNL] Force usage of a specific region of memory
1252 Region of memory to be used, from ss to ss+nn.
1253
1254 memmap=nn[KMG]#ss[KMG]
1255 [KNL,ACPI] Mark specific memory as ACPI data.
1256 Region of memory to be used, from ss to ss+nn.
1257
1258 memmap=nn[KMG]$ss[KMG]
1259 [KNL,ACPI] Mark specific memory as reserved.
1260 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001261 Example: Exclude memory from 0x18690000-0x1869ffff
1262 memmap=64K$0x18690000
1263 or
1264 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001265
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001266 memory_corruption_check=0/1 [X86]
1267 Some BIOSes seem to corrupt the first 64k of
1268 memory when doing things like suspend/resume.
1269 Setting this option will scan the memory
1270 looking for corruption. Enabling this will
1271 both detect corruption and prevent the kernel
1272 from using the memory being corrupted.
1273 However, its intended as a diagnostic tool; if
1274 repeatable BIOS-originated corruption always
1275 affects the same memory, you can use memmap=
1276 to prevent the kernel from using that memory.
1277
1278 memory_corruption_check_size=size [X86]
1279 By default it checks for corruption in the low
1280 64k, making this memory unavailable for normal
1281 use. Use this parameter to scan for
1282 corruption in more or less memory.
1283
1284 memory_corruption_check_period=seconds [X86]
1285 By default it checks for corruption every 60
1286 seconds. Use this parameter to check at some
1287 other rate. 0 disables periodic checking.
1288
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001289 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001290 Format: <integer>
1291 range: 0,4 : pattern number
1292 default : 0 <disable>
1293
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 meye.*= [HW] Set MotionEye Camera parameters
1295 See Documentation/video4linux/meye.txt.
1296
Andres Salomon8f368812007-10-12 23:04:06 +02001297 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1298 Multi-Function General Purpose Timers on AMD Geode
1299 platforms.
1300
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001301 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1302 the BIOS has incorrectly applied a workaround. TinyBIOS
1303 version 0.98 is known to be affected, 0.99 fixes the
1304 problem by letting the user disable the workaround.
1305
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306 mga= [HW,DRM]
1307
Randy Dunlap1c207f952008-11-19 15:36:16 -08001308 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1309 physical address is ignored.
1310
Mel Gorman6b74ab92008-07-23 21:26:49 -07001311 mminit_loglevel=
1312 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1313 parameter allows control of the logging verbosity for
1314 the additional memory initialisation checks. A value
1315 of 0 disables mminit logging and a level of 4 will
1316 log everything. Information is printed at KERN_DEBUG
1317 so loglevel=8 may also need to be specified.
1318
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 mousedev.tap_time=
1320 [MOUSE] Maximum time between finger touching and
1321 leaving touchpad surface for touch to be considered
1322 a tap and be reported as a left button click (for
1323 touchpads working in absolute mode only).
1324 Format: <msecs>
1325 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1326 reporting absolute coordinates, such as tablets
1327 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1328 reporting absolute coordinates, such as tablets
1329
1330 mpu401= [HW,OSS]
1331 Format: <io>,<irq>
1332
1333 MTD_Partition= [MTD]
1334 Format: <name>,<region-number>,<size>,<offset>
1335
Randy Dunlapa9913042005-10-23 12:57:11 -07001336 MTD_Region= [MTD] Format:
1337 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338
1339 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001340 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341
Ben Dooks9db829f2008-07-03 11:24:29 +01001342 mtdset= [ARM]
1343 ARM/S3C2412 JIVE boot control
1344
1345 See arch/arm/mach-s3c2412/mach-jive.c
1346
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001348 [HW] Make the MicroTouch USB driver use raw coordinates
1349 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350
1351 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1352
1353 NCR_D700= [HW,SCSI]
1354 See header of drivers/scsi/NCR_D700.c.
1355
1356 ncr5380= [HW,SCSI]
1357
1358 ncr53c400= [HW,SCSI]
1359
1360 ncr53c400a= [HW,SCSI]
1361
1362 ncr53c406a= [HW,SCSI]
1363
1364 ncr53c8xx= [HW,SCSI]
1365
1366 netdev= [NET] Network devices parameters
1367 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1368 Note that mem_start is often overloaded to mean
1369 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001370 This usage is only documented in each driver source
1371 file if at all.
1372
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001373 nf_conntrack.acct=
1374 [NETFILTER] Enable connection tracking flow accounting
1375 0 to disable accounting
1376 1 to enable accounting
1377 Default value depends on CONFIG_NF_CT_ACCT that is
1378 going to be removed in 2.6.29.
1379
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001381 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382
1383 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001384 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385
Trond Myklebusta72b4422006-01-03 09:55:41 +01001386 nfs.callback_tcpport=
1387 [NFS] set the TCP port on which the NFSv4 callback
1388 channel should listen.
1389
Trond Myklebust58df0952006-01-03 09:55:57 +01001390 nfs.idmap_cache_timeout=
1391 [NFS] set the maximum lifetime for idmapper cache
1392 entries.
1393
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001394 nfs.enable_ino64=
1395 [NFS] enable 64-bit inode numbers.
1396 If zero, the NFS client will fake up a 32-bit inode
1397 number for the readdir() and stat() syscalls instead
1398 of returning the full 64-bit number.
1399 The default is to return 64-bit inode numbers.
1400
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001401 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1402 when a NMI is triggered.
1403 Format: [state][,regs][,debounce][,die]
1404
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001405 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001407 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 emulation library even if a 387 maths coprocessor
1409 is present.
1410
Christoph Lameterc1aee212007-05-31 00:40:47 -07001411 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1412 caches in the slab allocator. Saves per-node memory,
1413 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001414
Randy Dunlapa9913042005-10-23 12:57:11 -07001415 noalign [KNL,ARM]
1416
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 noapic [SMP,APIC] Tells the kernel to not make use of any
1418 IOAPICs that may be present in the system.
1419
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 nobats [PPC] Do not use BATs for mapping kernel lowmem
1421 on "Classic" PPC cores.
1422
1423 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001424
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001425 nodelayacct [KNL] Disable per-task delay accounting
1426
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1428
Paul Mundt6902aa82008-09-21 17:14:42 +09001429 nodsp [SH] Disable hardware DSP at boot time.
1430
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001431 noefi [X86-32,X86-64] Disable EFI runtime services support.
1432
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 noexec [IA-64]
1434
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001435 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001436 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001438 noexec=off: disable non-executable mappings
1439
1440 noexec32 [X86-64]
1441 This affects only 32-bit executables.
1442 noexec32=on: enable non-executable mappings (default)
1443 read doesn't imply executable mappings
1444 noexec32=off: disable non-executable mappings
1445 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446
Paul Mundt6902aa82008-09-21 17:14:42 +09001447 nofpu [SH] Disable hardware FPU at boot time.
1448
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001449 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001450 register save and restore. The kernel will only save
1451 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452
Andi Kleen191679f2008-01-30 13:33:21 +01001453 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1454
Paul Mundt6902aa82008-09-21 17:14:42 +09001455 nohlt [BUGS=ARM,SH]
Randy Dunlapa9913042005-10-23 12:57:11 -07001456
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001457 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 instruction doesn't work correctly and not to
1459 use it.
1460
1461 nohalt [IA-64] Tells the kernel not to use the power saving
1462 function PAL_HALT_LIGHT when idle. This increases
1463 power-consumption. On the positive side, it reduces
1464 interrupt wake-up latency, which may improve performance
1465 in certain environments such as networked servers or
1466 real-time systems.
1467
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001468 nohz= [KNL] Boottime enable/disable dynamic ticks
1469 Valid arguments: on, off
1470 Default: on
1471
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001472 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 disable unhandled interrupt sources.
1474
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001475 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001476 broken timer IRQ sources.
1477
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 noisapnp [ISAPNP] Disables ISA PnP code.
1479
1480 noinitrd [RAM] Tells the kernel not to load any configured
1481 initial RAM disk.
1482
1483 nointroute [IA-64]
1484
Tony Luck0aa366f2007-07-20 11:22:30 -07001485 nojitter [IA64] Disables jitter checking for ITC timers.
1486
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001487 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001489 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001490
Suresh Siddha6e1cb382008-07-10 11:16:58 -07001491 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1492
Suresh Siddhaaf9d1382008-07-11 13:11:57 -07001493 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1494 default x2apic cluster mode on platforms
1495 supporting x2apic.
1496
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 noltlbs [PPC] Do not use large page/tlb entries for kernel
1498 lowmem mapping on PPC40x.
1499
Horms312f1f02006-02-22 09:57:55 +09001500 nomca [IA-64] Disable machine check abort handling
1501
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001502 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001503
Andres Salomon83d73842007-10-12 23:04:06 +02001504 nomfgpt [X86-32] Disable Multi-Function General Purpose
1505 Timer usage (for AMD Geode machines).
1506
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001507 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001508
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001509 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001510 with UP alternatives
1511
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 noresidual [PPC] Don't use residual data on PReP machines.
1513
Randy Dunlapa9913042005-10-23 12:57:11 -07001514 noresume [SWSUSP] Disables resume and restores original swap
1515 space.
1516
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 no-scroll [VGA] Disables scrollback.
1518 This is required for the Braillex ib80-piezo Braille
1519 reader made by F.H. Papenmeier (Germany).
1520
1521 nosbagart [IA-64]
1522
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001523 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001524
Len Brown61ec7562007-08-16 03:34:22 -04001525 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1526 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527
Dave Jones97842212007-07-15 23:41:05 -07001528 nosoftlockup [KNL] Disable the soft-lockup detector.
1529
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530 nosync [HW,M68K] Disables sync negotiation for all devices.
1531
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001532 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533
1534 nousb [USB] Disable the USB subsystem
1535
1536 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001537
Fenghua Yua6c75b862008-03-14 13:57:08 -07001538 nptcg= [IA64] Override max number of concurrent global TLB
1539 purges which is reported from either PAL_VM_SUMMARY or
1540 SAL PALO.
1541
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001542 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1543 one of ['zone', 'node', 'default'] can be specified
1544 This can be set from sysctl after boot.
1545 See Documentation/sysctl/vm.txt for details.
1546
Dave Jonesa61c2d72006-01-07 23:18:19 +00001547 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1548
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001549 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1550 Rather than timing out after 20 ms if an EC
1551 command is not properly ACKed, override the length
1552 of the timeout. We have interrupts disabled while
1553 waiting for the ACK, so if this is set too high
1554 interrupts *may* be lost!
1555
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 opl3= [HW,OSS]
1557 Format: <io>
1558
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 oprofile.timer= [HW]
1560 Use timer interrupt instead of performance counters
1561
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 osst= [HW,SCSI] SCSI Tape Driver
1563 Format: <buffer_size>,<write_threshold>
1564 See also Documentation/scsi/st.txt.
1565
1566 panic= [KNL] Kernel behaviour on panic
1567 Format: <timeout>
1568
1569 parkbd.port= [HW] Parallel port number the keyboard adapter is
1570 connected to, default is 0.
1571 Format: <parport#>
1572 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1573 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001574 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575
Randy Dunlapa9913042005-10-23 12:57:11 -07001576 parport= [HW,PPT] Specify parallel ports. 0 disables.
1577 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1578 Use 'auto' to force the driver to use any
1579 IRQ/DMA settings detected (the default is to
1580 ignore detected IRQ/DMA settings because of
1581 possible conflicts). You can specify the base
1582 address, IRQ, and DMA settings; IRQ and DMA
1583 should be numbers, or 'auto' (for using detected
1584 settings on that particular port), or 'nofifo'
1585 (to avoid using a FIFO even if it is detected).
1586 Parallel ports are assigned in the order they
1587 are specified on the command line, starting
1588 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589
Randy Dunlapa9913042005-10-23 12:57:11 -07001590 parport_init_mode= [HW,PPT]
1591 Configure VIA parallel port to operate in
1592 a specific mode. This is necessary on Pegasos
1593 computer where firmware has no options for setting
1594 up parallel port mode and sets it to spp.
1595 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 Format: [spp|ps2|epp|ecp|ecpepp]
1597
Randy Dunlapa9913042005-10-23 12:57:11 -07001598 pas2= [HW,OSS] Format:
1599 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1600
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601 pas16= [HW,SCSI]
1602 See header of drivers/scsi/pas16.c.
1603
Andrew Mortondd287792006-03-23 03:00:57 -08001604 pause_on_oops=
1605 Halt all CPUs after the first oops has been printed for
1606 the specified number of seconds. This is to be used if
1607 your oopses keep scrolling off the screen.
1608
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 pcbit= [HW,ISDN]
1610
1611 pcd. [PARIDE]
1612 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001613 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614
Randy Dunlapa9913042005-10-23 12:57:11 -07001615 pci=option[,option...] [PCI] various PCI subsystem options:
Andi Kleenc0115602008-08-22 09:53:39 +02001616 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001617 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001618 the hardware directly. Use this if your machine
1619 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001620 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001621 hardware access methods are allowed. Use this
1622 if you experience crashes upon bootup and you
1623 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001624 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001625 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001626 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001627 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001628 noaer [PCIE] If the PCIEAER kernel config parameter is
1629 enabled, this kernel boot option can be used to
1630 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001631 nodomains [PCI] Disable support for multiple PCI
1632 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001633 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001634 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001635 nomsi [MSI] If the PCI_MSI kernel config parameter is
1636 enabled, this kernel boot option can be used to
1637 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001638 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001639 routing table. These calls are known to be buggy
1640 on several machines and they hang the machine
1641 when used, but on other computers it's the only
1642 way to get the interrupt routing table. Try
1643 this option if the kernel is unable to allocate
1644 IRQs or discover secondary PCI buses on your
1645 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001646 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001647 Use with caution as certain devices share
1648 address decoders between ROMs and other
1649 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001650 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001651 expansion ROMs that do not already have
1652 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001653 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001654 assigned automatically to PCI devices. You can
1655 make the kernel exclude IRQs of your ISA cards
1656 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001657 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001658 of the PIRQ table (normally generated
1659 by the BIOS) if it is outside the
1660 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001661 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001662 useful if the kernel is unable to find your
1663 secondary buses and you want to tell it
1664 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001665 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001666 numbers ourselves, overriding
1667 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001668 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001669 in the BIOS $PIR table. This is needed on
1670 some systems with broken BIOSes, notably
1671 some HP Pavilion N5400 and Omnibook XE3
1672 notebooks. This will have no effect if ACPI
1673 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001674 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001675 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001676 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001677 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001678 routeirq Do IRQ routing for all PCI devices.
1679 This is normally done in pci_enable_device(),
1680 so this option is a temporary workaround
1681 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001682 skip_isa_align [X86] do not align io start addr, so can
1683 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001684 firmware [ARM] Do not re-enumerate the bus but instead
1685 just use the configuration from the
1686 bootloader. This is currently used on
1687 IXP2000 systems where the bus has to be
1688 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001689 noearly [X86] Don't do any early type 1 scanning.
1690 This might help on some broken boards which
1691 machine check when some devices' config space
1692 is read. But various workarounds are disabled
1693 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001694 bfsort Sort PCI devices into breadth-first order.
1695 This sorting is done to get a device
1696 order compatible with older (<= 2.4) kernels.
1697 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001698 cbiosize=nn[KMG] The fixed amount of bus space which is
1699 reserved for the CardBus bridge's IO window.
1700 The default value is 256 bytes.
1701 cbmemsize=nn[KMG] The fixed amount of bus space which is
1702 reserved for the CardBus bridge's memory
1703 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001704
Chuck Ebberte5665a42008-09-24 20:40:34 -04001705 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1706 Management.
1707 off Disable ASPM.
1708 force Enable ASPM even on devices that claim not to support it.
1709 WARNING: Forcing ASPM on may cause system lockups.
1710
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 pcmv= [HW,PCMCIA] BadgePAD 4
1712
1713 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001714 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715
1716 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1717 boot time.
1718 Format: { 0 | 1 }
1719 See arch/parisc/kernel/pdc_chassis.c
1720
1721 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001722 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723
1724 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001725 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726
1727 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001728 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729
1730 plip= [PPT,NET] Parallel port network link
1731 Format: { parport<nr> | timid | 0 }
1732 See also Documentation/parport.txt.
1733
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001734 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1735 Override pmtimer IOPort with a hex value.
1736 e.g. pmtmr=0x508
1737
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001738 pnp.debug [PNP]
1739 Enable PNP debug messages. This depends on the
1740 CONFIG_PNP_DEBUG_MESSAGES option.
1741
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 pnpacpi= [ACPI]
1743 { off }
1744
1745 pnpbios= [ISAPNP]
1746 { on | off | curr | res | no-curr | no-res }
1747
1748 pnp_reserve_irq=
1749 [ISAPNP] Exclude IRQs for the autoconfiguration
1750
1751 pnp_reserve_dma=
1752 [ISAPNP] Exclude DMAs for the autoconfiguration
1753
1754 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001755 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756
1757 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001758 [ISAPNP] Exclude memory regions for the
1759 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 Ranges are in pairs (memory base and size).
1761
Jason Baron346e15b2008-08-12 16:46:19 -04001762 dynamic_printk
1763 Enables pr_debug()/dev_dbg() calls if
1764 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1765 be switched on/off via <debugfs>/dynamic_printk/modules
1766
Ingo Molnar45807a12007-07-15 23:40:10 -07001767 print-fatal-signals=
1768 [KNL] debug: print fatal signals
1769 print-fatal-signals=1: print segfault info to
1770 the kernel console.
1771 default: off.
1772
Randy Dunlape84845c2007-07-15 23:40:25 -07001773 printk.time= Show timing data prefixed to each printk message line
1774 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1775
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001777 Format: [schedule,]<number>
1778 Param: "schedule" - profile schedule points.
1779 Param: <number> - step/bucket size as a power of 2 for
1780 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001781 Param: "sleep" - profile D-state sleeping (millisecs).
1782 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001783 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784
Randy Dunlapa9913042005-10-23 12:57:11 -07001785 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 Limit processor to maximum C-state
1787 max_cstate=9 overrides any DMI blacklist limit.
1788
Len Brown41c0d862005-12-28 12:43:51 -05001789 processor.nocst [HW,ACPI]
1790 Ignore the _CST method to determine C-states,
1791 instead using the legacy FADT method
1792
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1794 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001795 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796
Randy Dunlapa9913042005-10-23 12:57:11 -07001797 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1798 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1800 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001801 psmouse.resetafter= [HW,MOUSE]
1802 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803 (0 = never).
1804 psmouse.resolution=
1805 [HW,MOUSE] Set desired mouse resolution, in dpi.
1806 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001807 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808 0 = disabled, 1 = enabled (default).
1809
1810 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001811 Format:
1812 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
1814 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001815 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816
Kay Sieversdc8c8582007-08-15 12:25:38 +02001817 pty.legacy_count=
1818 [KNL] Number of legacy pty's. Overwrites compiled-in
1819 default number.
1820
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001821 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001822
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823 r128= [HW,DRM]
1824
1825 raid= [HW,RAID]
1826 See Documentation/md.txt.
1827
Randy Dunlapa9913042005-10-23 12:57:11 -07001828 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001829 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001830
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001832 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001834 rcupdate.blimit= [KNL,BOOT]
1835 Set maximum number of finished RCU callbacks to process
1836 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001837
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001838 rcupdate.qhimark= [KNL,BOOT]
1839 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001840 RCU callbacks over which batch limiting is disabled.
1841
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001842 rcupdate.qlowmark= [KNL,BOOT]
1843 Set threshold of queued RCU callbacks below which
1844 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001845
Olof Johanssonffdfc402005-09-06 15:17:19 -07001846 rdinit= [KNL]
1847 Format: <full_path>
1848 Run specified binary instead of /init from the ramdisk,
1849 used for early userspace startup. See initrd.
1850
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001851 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001853 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854
Paul Jackson46b6d942008-07-04 10:00:09 -07001855 relax_domain_level=
1856 [KNL, SMP] Set scheduler's default relax_domain_level.
1857 See Documentation/cpusets.txt.
1858
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1860
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001861 reservetop= [X86-32]
Zachary Amsden461a9aff2006-09-25 23:32:25 -07001862 Format: nn[KMG]
1863 Reserves a hole at the top of the kernel virtual
1864 address space.
1865
Vivek Goyal7e962872006-09-27 01:50:44 -07001866 reset_devices [KNL] Force drivers to reset the underlying device
1867 during initialization.
1868
Randy Dunlapa9913042005-10-23 12:57:11 -07001869 resume= [SWSUSP]
1870 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001872 resume_offset= [SWSUSP]
1873 Specify the offset from the beginning of the partition
1874 given by "resume=" at which the swap header is located,
1875 in <PAGE_SIZE> units (needed only for swap files).
1876 See Documentation/power/swsusp-and-swap-files.txt
1877
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001878 retain_initrd [RAM] Keep initrd memory after extraction
1879
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880 rhash_entries= [KNL,NET]
1881 Set number of hash buckets for route cache
1882
1883 riscom8= [HW,SERIAL]
1884 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1885
1886 ro [KNL] Mount root device read-only on boot
1887
1888 root= [KNL] Root filesystem
1889
1890 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1891 mount the root filesystem
1892
1893 rootflags= [KNL] Set root filesystem mount option string
1894
1895 rootfstype= [KNL] Set root filesystem type
1896
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001897 rootwait [KNL] Wait (indefinitely) for root device to show up.
1898 Useful for devices that are detected asynchronously
1899 (e.g. USB and MMC devices).
1900
James Morris20510f22007-10-16 23:31:32 -07001901 root_plug.vendor_id=
1902 [ROOTPLUG] Override the default vendor ID
1903
1904 root_plug.product_id=
1905 [ROOTPLUG] Override the default product ID
1906
1907 root_plug.debug=
1908 [ROOTPLUG] Enable debugging output
1909
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910 rw [KNL] Mount root device read-write on boot
1911
1912 S [KNL] Run init in single mode
1913
1914 sa1100ir [NET]
1915 See drivers/net/irda/sa1100_ir.c.
1916
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001918
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1920 Format: <io>[,<timeout>[,<isapnp>]]
1921
1922 scsi_debug_*= [SCSI]
1923 See drivers/scsi/scsi_debug.c.
1924
1925 scsi_default_dev_flags=
1926 [SCSI] SCSI default device flags
1927 Format: <integer>
1928
1929 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1930 Format: <vendor>:<model>:<flags>
1931 (flags are integer value)
1932
Randy Dunlap6af66322007-11-14 16:52:25 -08001933 scsi_logging_level= [SCSI] a bit mask of logging levels
1934 See drivers/scsi/scsi_logging.h for bits. Also
1935 settable via sysctl at dev.scsi.logging_level
1936 (/proc/sys/dev/scsi/logging_level).
1937 There is also a nice 'scsi_logging_level' script in the
1938 S390-tools package, available for download at
1939 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001941 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1942 discovered. async scans them in kernel threads,
1943 allowing boot to proceed. none ignores them, expecting
1944 user space to do the scan.
1945
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 selinux [SELINUX] Disable or enable SELinux at boot time.
1947 Format: { "0" | "1" }
1948 See security/selinux/Kconfig help text.
1949 0 -- disable.
1950 1 -- enable.
1951 Default value is set via kernel config option.
1952 If enabled at boot time, /selinux/disable can be used
1953 later to disable prior to initial policy load.
1954
James Morris4e5ab4c2006-06-09 00:33:33 -07001955 selinux_compat_net =
1956 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001957 Format: { "0" | "1" }
1958 0 -- use new secmark-based packet controls
1959 1 -- use legacy packet controls
1960 Default value is 0 (preferred).
1961 Value can be changed at runtime via
1962 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001963
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001964 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966 shapers= [NET]
1967 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001968
Yinghai Lub05f78f2008-08-22 01:32:50 -07001969 show_msr= [x86] show boot-time MSR settings
1970 Format: { <integer> }
1971 Show boot-time (BIOS-initialized) MSR settings.
1972 The parameter means the number of CPUs to show,
1973 for example 1 means boot CPU only.
1974
Linus Torvalds1da177e2005-04-16 15:20:36 -07001975 sim710= [SCSI,HW]
1976 See header of drivers/scsi/sim710.c.
1977
1978 simeth= [IA-64]
1979 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001980
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981 slram= [HW,MTD]
1982
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001983 slub_debug[=options[,slabs]] [MM, SLUB]
1984 Enabling slub_debug allows one to determine the
1985 culprit if slab objects become corrupted. Enabling
1986 slub_debug can create guard zones around objects and
1987 may poison objects when not in use. Also tracks the
1988 last alloc / free. For more information see
1989 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001990
1991 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001992 Determines the maximum allowed order for slabs.
1993 A high setting may cause OOMs due to memory
1994 fragmentation. For more information see
1995 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001996
1997 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001998 The minimum number of objects per slab. SLUB will
1999 increase the slab order up to slub_max_order to
2000 generate a sufficiently large slab able to contain
2001 the number of objects indicated. The higher the number
2002 of objects the smaller the overhead of tracking slabs
2003 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002004 For more information see Documentation/vm/slub.txt.
2005
2006 slub_min_order= [MM, SLUB]
2007 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002008 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002009 For more information see Documentation/vm/slub.txt.
2010
2011 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002012 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002013 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002014 allocs to different slabs. Debug options disable
2015 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002016 For more information see Documentation/vm/slub.txt.
2017
Linus Torvalds1da177e2005-04-16 15:20:36 -07002018 smart2= [HW]
2019 Format: <io1>[,<io2>[,...,<io8>]]
2020
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002021 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002022 attempt to substitute SMP alternatives once at boot.
2023
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002024 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2025 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2026 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2027 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2028 smsc-ircc2.ircc_irq= [HW] IRQ line
2029 smsc-ircc2.ircc_dma= [HW] DMA channel
2030 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2031 0: Toshiba Satellite 1800 (GP data pin select)
2032 1: Fast pin select (default)
2033 2: ATC IRMode
2034
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035 snd-ad1816a= [HW,ALSA]
2036
2037 snd-ad1848= [HW,ALSA]
2038
2039 snd-ali5451= [HW,ALSA]
2040
2041 snd-als100= [HW,ALSA]
2042
2043 snd-als4000= [HW,ALSA]
2044
2045 snd-azt2320= [HW,ALSA]
2046
2047 snd-cmi8330= [HW,ALSA]
2048
2049 snd-cmipci= [HW,ALSA]
2050
2051 snd-cs4231= [HW,ALSA]
2052
2053 snd-cs4232= [HW,ALSA]
2054
2055 snd-cs4236= [HW,ALSA]
2056
2057 snd-cs4281= [HW,ALSA]
2058
2059 snd-cs46xx= [HW,ALSA]
2060
2061 snd-dt019x= [HW,ALSA]
2062
2063 snd-dummy= [HW,ALSA]
2064
2065 snd-emu10k1= [HW,ALSA]
2066
2067 snd-ens1370= [HW,ALSA]
2068
2069 snd-ens1371= [HW,ALSA]
2070
2071 snd-es968= [HW,ALSA]
2072
2073 snd-es1688= [HW,ALSA]
2074
2075 snd-es18xx= [HW,ALSA]
2076
2077 snd-es1938= [HW,ALSA]
2078
2079 snd-es1968= [HW,ALSA]
2080
2081 snd-fm801= [HW,ALSA]
2082
2083 snd-gusclassic= [HW,ALSA]
2084
2085 snd-gusextreme= [HW,ALSA]
2086
2087 snd-gusmax= [HW,ALSA]
2088
2089 snd-hdsp= [HW,ALSA]
2090
2091 snd-ice1712= [HW,ALSA]
2092
2093 snd-intel8x0= [HW,ALSA]
2094
2095 snd-interwave= [HW,ALSA]
2096
2097 snd-interwave-stb=
2098 [HW,ALSA]
2099
2100 snd-korg1212= [HW,ALSA]
2101
2102 snd-maestro3= [HW,ALSA]
2103
2104 snd-mpu401= [HW,ALSA]
2105
2106 snd-mtpav= [HW,ALSA]
2107
2108 snd-nm256= [HW,ALSA]
2109
2110 snd-opl3sa2= [HW,ALSA]
2111
2112 snd-opti92x-ad1848=
2113 [HW,ALSA]
2114
2115 snd-opti92x-cs4231=
2116 [HW,ALSA]
2117
2118 snd-opti93x= [HW,ALSA]
2119
2120 snd-pmac= [HW,ALSA]
2121
2122 snd-rme32= [HW,ALSA]
2123
2124 snd-rme96= [HW,ALSA]
2125
2126 snd-rme9652= [HW,ALSA]
2127
2128 snd-sb8= [HW,ALSA]
2129
2130 snd-sb16= [HW,ALSA]
2131
2132 snd-sbawe= [HW,ALSA]
2133
2134 snd-serial= [HW,ALSA]
2135
2136 snd-sgalaxy= [HW,ALSA]
2137
2138 snd-sonicvibes= [HW,ALSA]
2139
2140 snd-sun-amd7930=
2141 [HW,ALSA]
2142
2143 snd-sun-cs4231= [HW,ALSA]
2144
2145 snd-trident= [HW,ALSA]
2146
2147 snd-usb-audio= [HW,ALSA,USB]
2148
2149 snd-via82xx= [HW,ALSA]
2150
2151 snd-virmidi= [HW,ALSA]
2152
2153 snd-wavefront= [HW,ALSA]
2154
2155 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002156
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002157 softlockup_panic=
2158 [KNL] Should the soft-lockup detector generate panics.
2159
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2161 See Documentation/sonypi.txt
2162
2163 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002164 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165
2166 spia_io_base= [HW,MTD]
2167 spia_fio_base=
2168 spia_pedr=
2169 spia_peddr=
2170
2171 sscape= [HW,OSS]
2172 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002173
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2175 See Documentation/scsi/st.txt.
2176
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002177 stacktrace [FTRACE]
2178 Enabled the stack tracer on boot up.
2179
Linus Torvalds1da177e2005-04-16 15:20:36 -07002180 sti= [PARISC,HW]
2181 Format: <num>
2182 Set the STI (builtin display/keyboard on the HP-PARISC
2183 machines) console (graphic card) which should be used
2184 as the initial boot-console.
2185 See also comment in drivers/video/console/sticore.c.
2186
2187 sti_font= [HW]
2188 See comment in drivers/video/console/sticore.c.
2189
2190 stifb= [HW]
2191 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2192
Greg Banks42a7fc42007-03-06 01:42:23 -08002193 sunrpc.pool_mode=
2194 [NFS]
2195 Control how the NFS server code allocates CPUs to
2196 service thread pools. Depending on how many NICs
2197 you have and where their interrupts are bound, this
2198 option will affect which CPUs will do NFS serving.
2199 Note: this parameter cannot be changed while the
2200 NFS server is running.
2201
2202 auto the server chooses an appropriate mode
2203 automatically using heuristics
2204 global a single global pool contains all CPUs
2205 percpu one pool for each CPU
2206 pernode one pool for each NUMA node (equivalent
2207 to global on non-NUMA machines)
2208
Linus Torvalds1da177e2005-04-16 15:20:36 -07002209 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002210
Linus Torvalds1da177e2005-04-16 15:20:36 -07002211 switches= [HW,M68k]
2212
2213 sym53c416= [HW,SCSI]
2214 See header of drivers/scsi/sym53c416.c.
2215
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002216 sysrq_always_enabled
2217 [KNL]
2218 Ignore sysrq setting - this boot parameter will
2219 neutralize any effect of /proc/sys/kernel/sysrq.
2220 Useful for debugging.
2221
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222 t128= [HW,SCSI]
2223 See header of drivers/scsi/t128.c.
2224
2225 tdfx= [HW,DRM]
2226
David Brownell77437fd2008-07-23 21:28:33 -07002227 test_suspend= [SUSPEND]
2228 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2229 standby suspend) as the system sleep state to briefly
2230 enter during system startup. The system is woken from
2231 this state using a wakeup-capable RTC alarm.
2232
Linus Torvalds1da177e2005-04-16 15:20:36 -07002233 thash_entries= [KNL,NET]
2234 Set number of hash buckets for TCP connection
2235
Len Brownf8707ec2007-08-12 00:12:54 -04002236 thermal.act= [HW,ACPI]
2237 -1: disable all active trip points in all thermal zones
2238 <degrees C>: override all lowest active trip points
2239
Len Brownc52a7412007-08-14 15:49:32 -04002240 thermal.crt= [HW,ACPI]
2241 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002242 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002243
Len Brownf5487142007-08-12 00:12:44 -04002244 thermal.nocrt= [HW,ACPI]
2245 Set to disable actions on ACPI thermal zone
2246 critical and hot trip points.
2247
Len Brown72b33ef2007-08-12 00:12:17 -04002248 thermal.off= [HW,ACPI]
2249 1: disable ACPI thermal control
2250
Len Browna70cdc52007-08-12 00:12:35 -04002251 thermal.psv= [HW,ACPI]
2252 -1: disable all passive trip points
2253 <degrees C>: override all passive trip points to this value
2254
Len Brown730ff342007-08-12 00:12:26 -04002255 thermal.tzp= [HW,ACPI]
2256 Specify global default ACPI thermal zone polling rate
2257 <deci-seconds>: poll all this frequency
2258 0: no polling (default)
2259
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260 tmscsim= [HW,SCSI]
2261 See comment before function dc390_setup() in
2262 drivers/scsi/tmscsim.c.
2263
2264 tp720= [HW,PS2]
2265
2266 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002267 Format:
2268 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2269
Randy Dunlapa9913042005-10-23 12:57:11 -07002270 turbografx.map[2|3]= [HW,JOY]
2271 TurboGraFX parallel port interface
2272 Format:
2273 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002274 See also Documentation/input/joystick-parport.txt
2275
2276 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2277 See header of drivers/scsi/u14-34f.c.
2278
2279 uart401= [HW,OSS]
2280 Format: <io>,<irq>
2281
2282 uart6850= [HW,OSS]
2283 Format: <io>,<irq>
2284
Alan Stern5f8364b2006-12-05 16:29:55 -05002285 uhci-hcd.ignore_oc=
2286 [USB] Ignore overcurrent events (default N).
2287 Some badly-designed motherboards generate lots of
2288 bogus events, for ports that aren't wired to
2289 anything. Set this parameter to avoid log spamming.
2290 Note that genuine overcurrent events won't be
2291 reported either.
2292
Simon Arlotte3a61b02008-07-19 23:32:54 +01002293 unknown_nmi_panic
2294 [X86-32,X86-64]
2295 Set unknown_nmi_panic=1 early on boot.
2296
Alan Sternb5e795f2007-02-20 15:00:53 -05002297 usbcore.autosuspend=
2298 [USB] The autosuspend time delay (in seconds) used
2299 for newly-detected USB devices (default 2). This
2300 is the time required before an idle device will be
2301 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002302 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002303
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002304 usbcore.usbfs_snoop=
2305 [USB] Set to log all usbfs traffic (default 0 = off).
2306
2307 usbcore.blinkenlights=
2308 [USB] Set to cycle leds on hubs (default 0 = off).
2309
2310 usbcore.old_scheme_first=
2311 [USB] Start with the old device initialization
2312 scheme (default 0 = off).
2313
2314 usbcore.use_both_schemes=
2315 [USB] Try the other device initialization scheme
2316 if the first one fails (default 1 = enabled).
2317
2318 usbcore.initial_descriptor_timeout=
2319 [USB] Specifies timeout for the initial 64-byte
2320 USB_REQ_GET_DESCRIPTOR request in milliseconds
2321 (default 5000 = 5.0 seconds).
2322
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323 usbhid.mousepoll=
2324 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002325
Paul Jackson200001e2008-06-25 05:44:46 -07002326 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2327 kernel's map of available physical RAM.
2328
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002329 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002330 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002331 vdso=1: enable VDSO (default)
2332 vdso=0: disable VDSO mapping
2333
Roland McGrathaf65d642008-01-30 13:30:43 +01002334 vdso32= [X86-32,X86-64]
2335 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2336 vdso32=1: enable 32-bit VDSO (default)
2337 vdso32=0: disable 32-bit VDSO mapping
2338
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002339 vector= [IA-64,SMP]
2340 vector=percpu: enable percpu vector domain
2341
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342 video= [FB] Frame buffer configuration
2343 See Documentation/fb/modedb.txt.
2344
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002345 vga= [BOOT,X86-32] Select a particular video mode
Uwe Hermann71cced62008-10-20 09:32:21 -07002346 See Documentation/x86/i386/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002347 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 Use vga=ask for menu.
2349 This is actually a boot loader parameter; the value is
2350 passed to the kernel using a special protocol.
2351
Randy Dunlapa9913042005-10-23 12:57:11 -07002352 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002353 size of <nn>. This can be used to increase the
2354 minimum size (128MB on x86). It can also be used to
2355 decrease the size and leave more room for directly
2356 mapped kernel RAM.
2357
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002358 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2359 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002360
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002361 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2362 Format: <command>
2363
2364 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2365 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002366
Linus Torvalds1da177e2005-04-16 15:20:36 -07002367 waveartist= [HW,OSS]
2368 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002369
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370 wd33c93= [HW,SCSI]
2371 See header of drivers/scsi/wd33c93.c.
2372
2373 wd7000= [HW,SCSI]
2374 See header of drivers/scsi/wd7000.c.
2375
2376 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002377 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002378
2379 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2380 xd_geo= See header of drivers/block/xd.c.
2381
2382 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002383 Format:
2384 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385
Andi Kleena62eaf12006-02-16 23:41:58 +01002386 norandmaps Don't use address space randomization
2387 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2388
Randy Dunlapa9913042005-10-23 12:57:11 -07002389______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390
2391TODO:
2392
2393 Add documentation for ALSA options.
2394 Add more DRM drivers.