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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.
Eduard - Gabriel Munteanub9ce08c2008-08-10 20:14:03 +030052 KMEMTRACE kmemtrace is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070053 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070062 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070063 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070066 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070069 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070073 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
James Morris20510f22007-10-16 23:31:32 -070080 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
84 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070085 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090088 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070091 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 gamecon.map[2|3]=
755 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
756 support via parallel port (up to 5 devices per port)
757 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
758 See also Documentation/input/joystick-parport.txt
759
760 gamma= [HW,DRM]
761
Yinghai Luaaf23042008-01-30 13:33:09 +0100762 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
763 Format: off | on
764 default: on
765
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 gdth= [HW,SCSI]
767 See header of drivers/scsi/gdth.c.
768
769 gpt [EFI] Forces disk with valid GPT signature but
770 invalid Protective MBR to be treated as GPT.
771
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772 gvp11= [HW,SCSI]
773
774 hashdist= [KNL,NUMA] Large hashes allocated during boot
775 are distributed across NUMA nodes. Defaults on
776 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700777 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778
779 hcl= [IA-64] SGI's Hardware Graph compatibility layer
780
781 hd= [EIDE] (E)IDE hard drive subsystem geometry
782 Format: <cyl>,<head>,<sect>
783
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
785 size of <nn>. This works even on boxes that have no
786 highmem otherwise. This also works to reduce highmem
787 size on bigger boxes.
788
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800789 highres= [KNL] Enable/disable high resolution timer mode.
790 Valid parameters: "on", "off"
791 Default: "on"
792
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 hisax= [HW,ISDN]
794 See Documentation/isdn/README.HiSax.
795
Andi Kleenb4718e62008-07-23 21:27:51 -0700796 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
797 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700798 On x86-64 and powerpc, this option can be specified
799 multiple times interleaved with hugepages= to reserve
800 huge pages of different sizes. Valid pages sizes on
801 x86-64 are 2M (when the CPU supports "pse") and 1G
802 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700803 Note that 1GB pages can only be allocated at boot time
804 using hugepages= and not freed afterwards.
Nick Piggine11bfbf2008-07-23 21:27:52 -0700805 default_hugepagesz=
806 [same as hugepagesz=] The size of the default
807 HugeTLB page size. This is the size represented by
808 the legacy /proc/ hugepages APIs, used for SHM, and
809 default size when mounting hugetlbfs filesystems.
810 Defaults to the default architecture's huge page size
811 if not specified.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812
Paul Mundt6902aa82008-09-21 17:14:42 +0900813 hlt [BUGS=ARM,SH]
814
Jiri Kosina36d95732008-10-06 02:51:09 -0400815 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200817 i8042.dumbkbd [HW] Pretend that controller can only read data from
818 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 (Don't attempt to blink the leds)
820 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500821 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400822 i8042.noloop [HW] Disable the AUX Loopback command while probing
823 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 i8042.nomux [HW] Don't check presence of an active multiplexing
825 controller
826 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
827 controllers
828 i8042.panicblink=
829 [HW] Frequency with which keyboard LEDs should blink
830 when kernel panics (default is 0.5 sec)
831 i8042.reset [HW] Reset the controller during init and cleanup
832 i8042.unlock [HW] Unlock (ignore) the keylock
833
834 i810= [HW,DRM]
835
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700836 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
837 indicates that the driver is running on unsupported
838 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
840 does not match list of supported models.
841 i8k.power_status
842 [HW] Report power status in /proc/i8k
843 (disabled by default)
844 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
845 capability is set.
846
847 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
848 See Documentation/mca.txt.
849
850 icn= [HW,ISDN]
851 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
852
853 ide= [HW] (E)IDE subsystem
Greg Kroah-Hartmana594eeb2008-04-18 00:46:20 +0200854 Format: ide=nodma or ide=doubler
Randy Dunlap1c10e932008-03-07 21:53:50 +0100855 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100858 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859
Andi Kleenf039b752007-05-02 19:27:12 +0200860 idle= [X86]
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800861 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Andi Kleenf039b752007-05-02 19:27:12 +0200862 Poll forces a polling idle loop that can slightly improves the performance
863 of waking up a idle CPU, but will use a lot of power and make the system
864 run hot. Not recommended.
865 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
866 to not use it because it doesn't save as much power as a normal idle
867 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
868 as idle=poll.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800869 idle=halt. Halt is forced to be used for CPU idle.
870 In such case C2/C3 won't be used again.
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800871 idle=nomwait. Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700872
Denis Cheng594765a2008-02-06 02:57:49 +0100873 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
874 Claim all unknown PCI IDE storage controllers.
875
Ingo Molnar792908222006-12-06 20:40:51 -0800876 ignore_loglevel [KNL]
877 Ignore loglevel setting - this will print /all/
878 kernel messages to the console. Useful for debugging.
879
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 ihash_entries= [KNL]
881 Set number of hash buckets for inode cache.
882
883 in2000= [HW,SCSI]
884 See header of drivers/scsi/in2000.c.
885
886 init= [KNL]
887 Format: <full_path>
888 Run specified binary instead of /sbin/init as init
889 process.
890
891 initcall_debug [KNL] Trace initcalls as they are executed. Useful
892 for working out where the kernel is dying during
893 startup.
894
895 initrd= [BOOT] Specify the location of the initial ramdisk
896
897 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
898 Format: <irq>
899
900 inttest= [IA64]
901
Pavel Machekb552da82008-03-19 15:58:11 +0100902 iommu= [x86]
903 off
904 force
905 noforce
906 biomerge
907 panic
908 nopanic
909 merge
910 nomerge
911 forcesac
912 soft
913
914
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700915 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
916 off
917 Disable intel iommu driver.
918 igfx_off [Default Off]
919 By default, gfx is mapped as normal device. If a gfx
920 device has a dedicated DMAR unit, the DMAR unit is
921 bypassed by not enabling DMAR with this option. In
922 this case, gfx device will use physical address for
923 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700924 forcedac [x86_64]
925 With this option iommu will not optimize to look
926 for io virtual address below 32 bit forcing dual
927 address cycle on pci bus for cards supporting greater
928 than 32 bit addressing. The default is to look
929 for translation below 32 bit and if not available
930 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800931 strict [Default Off]
932 With this option on every unmap_single operation will
933 result in a hardware IOTLB flush operation as opposed
934 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700935
Rene Hermanb02aae92008-01-30 13:30:05 +0100936 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100937 0x80
938 Standard port 0x80 based delay
939 0xed
940 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100941 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100942 Simple two microseconds delay
943 none
944 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100945
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 io7= [HW] IO7 for Marvel based alpha systems
947 See comment before marvel_specify_io7 in
948 arch/alpha/kernel/core_marvel.c.
949
950 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400951 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952
953 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700954 See comment before ip2_setup() in
955 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956
957 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
958 See header of drivers/scsi/ips.c.
959
Simon Horman72c4a132006-09-13 19:57:18 -0700960 ports= [IP_VS_FTP] IPVS ftp helper module
961 Default is 21.
962 Up to 8 (IP_VS_APP_MAX_PORTS) ports
963 may be specified.
964 Format: <port>,<port>....
965
Alan Cox200803d2005-06-28 20:45:18 -0700966 irqfixup [HW]
967 When an interrupt is not handled search all handlers
968 for it. Intended to get systems with badly broken
969 firmware running.
970
971 irqpoll [HW]
972 When an interrupt is not handled search all handlers
973 for it. Also check all handlers each timer
974 interrupt. Intended to get systems with badly broken
975 firmware running.
976
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700978 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979
980 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800981 Format:
982 <cpu number>,...,<cpu number>
983 or
Li Zefanb225d442008-11-06 12:53:39 -0800984 <cpu number>-<cpu number>
985 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -0800986 or a mixture
987 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -0800988
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 This option can be used to specify one or more CPUs
990 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -0800991 algorithms. You can move a process onto or off an
992 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993 <cpu number> begins at 0 and the maximum value is
994 "number of CPUs in system - 1".
995
996 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700997 alternative -- manually setting the CPU mask of all
998 tasks in the system -- can cause problems and
999 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000
Randy Dunlapa9913042005-10-23 12:57:11 -07001001 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002
1003 js= [HW,JOY] Analog joystick
1004 See Documentation/input/joystick.txt.
1005
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001006 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001007 specifies the amount of memory usable by the kernel
1008 for non-movable allocations. The requested amount is
1009 spread evenly throughout all nodes in the system. The
1010 remaining memory in each node is used for Movable
1011 pages. In the event, a node is too small to have both
1012 kernelcore and Movable pages, kernelcore pages will
1013 take priority and other nodes will have a larger number
1014 of kernelcore pages. The Movable zone is used for the
1015 allocation of pages that may be reclaimed or moved
1016 by the page migration subsystem. This means that
1017 HugeTLB pages may not be allocated from this zone.
1018 Note that allocations like PTEs-from-HighMem still
1019 use the HighMem zone if it exists, and the Normal
1020 zone if it does not.
1021
Eduard - Gabriel Munteanub9ce08c2008-08-10 20:14:03 +03001022 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1023 Controls whether kmemtrace is enabled
1024 at boot-time.
1025
1026 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1027 subbufs kmemtrace's relay channel has. Set this
1028 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1029 you experience buffer overruns.
1030
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001031 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -07001032 is similar to kernelcore except it specifies the
1033 amount of memory used for migratable allocations.
1034 If both kernelcore and movablecore is specified,
1035 then kernelcore will be at *least* the specified
1036 value but may be more. If movablecore on its own
1037 is specified, the administrator must be careful
1038 that the amount of memory usable for all allocations
1039 is not too small.
1040
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 keepinitrd [HW,ARM]
1042
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001043 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 in oops dumps.
1045
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001046 kgdboc= [HW] kgdb over consoles.
1047 Requires a tty driver that supports console polling.
1048 (only serial suported for now)
1049 Format: <serial_device>[,baud]
1050
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001051 kmac= [MIPS] korina ethernet MAC address.
1052 Configure the RouterBoard 532 series on-chip
1053 Ethernet adapter MAC address.
1054
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 l2cr= [PPC]
1056
Robert Brosea78bfbf2008-03-29 07:20:23 +11001057 l3cr= [PPC]
1058
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001059 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001060 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001062 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001063 C2 power state.
1064
FD Camifcb71f62008-01-06 19:08:56 +01001065 libata.dma= [LIBATA] DMA control
1066 libata.dma=0 Disable all PATA and SATA DMA
1067 libata.dma=1 PATA and SATA Disk DMA only
1068 libata.dma=2 ATAPI (CDROM) DMA only
1069 libata.dma=4 Compact Flash DMA only
1070 Combinations also work, so libata.dma=3 enables DMA
1071 for disks and CDROMs, but not CFs.
1072
Dave Jones78e70c22007-09-27 11:50:13 -04001073 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1074 when set.
1075 Format: <int>
1076
Tejun Heo33267322008-02-13 09:15:09 +09001077 libata.force= [LIBATA] Force configurations. The format is comma
1078 separated list of "[ID:]VAL" where ID is
1079 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1080 matching port, link or device. Basically, it matches
1081 the ATA ID string printed on console by libata. If
1082 the whole ID part is omitted, the last PORT and DEVICE
1083 values are used. If ID hasn't been specified yet, the
1084 configuration applies to all ports, links and devices.
1085
1086 If only DEVICE is omitted, the parameter applies to
1087 the port and all links and devices behind it. DEVICE
1088 number of 0 either selects the first device or the
1089 first fan-out link behind PMP device. It does not
1090 select the host link. DEVICE number of 15 selects the
1091 host link and device attached to it.
1092
1093 The VAL specifies the configuration to force. As long
1094 as there's no ambiguity shortcut notation is allowed.
1095 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1096 The following configurations can be forced.
1097
1098 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1099 Any ID with matching PORT is used.
1100
1101 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1102
1103 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1104 udma[/][16,25,33,44,66,100,133] notation is also
1105 allowed.
1106
1107 * [no]ncq: Turn on or off NCQ.
1108
Tejun Heo05944bd2008-08-13 20:19:09 +09001109 * nohrst, nosrst, norst: suppress hard, soft
1110 and both resets.
1111
Tejun Heo33267322008-02-13 09:15:09 +09001112 If there are multiple matching configurations changing
1113 the same attribute, the last one is used.
1114
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001116 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001118 lockd.nlm_grace_period=P [NFS] Assign grace period.
1119 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001121 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1122 Format: <integer>
1123
1124 lockd.nlm_timeout=T [NFS] Assign timeout value.
1125 Format: <integer>
1126
1127 lockd.nlm_udpport=M [NFS] Assign UDP port.
1128 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129
1130 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1131 Format: <irq>
1132
1133 loglevel= All Kernel Messages with a loglevel smaller than the
1134 console loglevel will be printed to the console. It can
1135 also be changed with klogd or other programs. The
1136 loglevels are defined as follows:
1137
1138 0 (KERN_EMERG) system is unusable
1139 1 (KERN_ALERT) action must be taken immediately
1140 2 (KERN_CRIT) critical conditions
1141 3 (KERN_ERR) error conditions
1142 4 (KERN_WARNING) warning conditions
1143 5 (KERN_NOTICE) normal but significant condition
1144 6 (KERN_INFO) informational
1145 7 (KERN_DEBUG) debug-level messages
1146
1147 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001148 Format: { n | nk | nM }
1149 n must be a power of two. The default size
1150 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151
Randy Dunlapaccaa242007-10-16 01:29:37 -07001152 logo.nologo [FB] Disables display of the built-in Linux logo.
1153 This may be used to provide more screen space for
1154 kernel log messages and is useful when debugging
1155 kernel boot problems.
1156
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157 lp=0 [LP] Specify parallel ports to use, e.g,
1158 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1159 lp=reset first parallel port). 'lp=0' disables the
1160 lp=auto printer driver. 'lp=reset' (which can be
1161 specified in addition to the ports) causes
1162 attached printers to be reset. Using
1163 lp=port1,port2,... specifies the parallel ports
1164 to associate lp devices with, starting with
1165 lp0. A port specification may be 'none' to skip
1166 that lp device, or a parport name such as
1167 'parport0'. Specifying 'lp=auto' instead of a
1168 port specification list means that device IDs
1169 from each port should be examined, to see if
1170 an IEEE 1284-compliant printer is attached; if
1171 so, the driver will manage that printer.
1172 See also header of drivers/char/lp.c.
1173
1174 lpj=n [KNL]
1175 Sets loops_per_jiffy to given constant, thus avoiding
1176 time-consuming boot-time autodetection (up to 250 ms per
1177 CPU). 0 enables autodetection (default). To determine
1178 the correct value for your kernel, boot with normal
1179 autodetection and see what value is printed. Note that
1180 on SMP systems the preset will be applied to all CPUs,
1181 which is likely to cause problems if your CPUs need
1182 significantly divergent settings. An incorrect value
1183 will cause delays in the kernel to be wrong, leading to
1184 unpredictable I/O errors and other breakage. Although
1185 unlikely, in the extreme case this might damage your
1186 hardware.
1187
1188 ltpc= [NET]
1189 Format: <io>,<irq>,<dma>
1190
Randy Dunlapa9913042005-10-23 12:57:11 -07001191 mac5380= [HW,SCSI] Format:
1192 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193
Randy Dunlapa9913042005-10-23 12:57:11 -07001194 machvec= [IA64] Force the use of a particular machine-vector
1195 (machvec) in a generic kernel.
1196 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197
Randy Dunlapa9913042005-10-23 12:57:11 -07001198 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199 be mounted
1200 Format: <1-256>
1201
1202 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001203 should make use of. maxcpus=n : n >= 0 limits the
1204 kernel to using 'n' processors. n=0 is a special case,
1205 it is equivalent to "nosmp", which also disables
1206 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207
Randy Dunlap1c207f92008-11-19 15:36:16 -08001208 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1209 or equal to this physical address is ignored.
Bob Picco2b2c3752005-06-29 18:00:00 -07001210
Randy Dunlapa9913042005-10-23 12:57:11 -07001211 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 Should be between 1 and 2^32-1.
1213
1214 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001215 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 Should be between 1 and 16384.
1217
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 mcatest= [IA-64]
1219
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001220 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221
Uwe Hermann71cced62008-10-20 09:32:21 -07001222 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001223
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224 md= [HW] RAID subsystems devices and level
1225 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001226
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227 mdacon= [MDA]
1228 Format: <first>,<last>
1229 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001230
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1232 Amount of memory to be used when the kernel is not able
1233 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001234 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 address space collisions. Without memmap= PCI devices
1236 could be placed at addresses belonging to unused RAM.
1237
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001238 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 memory.
1240
Paul Mundt6902aa82008-09-21 17:14:42 +09001241 memchunk=nn[KMG]
1242 [KNL,SH] Allow user to override the default size for
1243 per-device physically contiguous DMA buffers.
1244
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001245 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246 E820 memory map, as specified by the user.
1247 Such memmap=exactmap lines can be constructed based on
1248 BIOS output or other requirements. See the memmap=nn@ss
1249 option description.
1250
1251 memmap=nn[KMG]@ss[KMG]
1252 [KNL] Force usage of a specific region of memory
1253 Region of memory to be used, from ss to ss+nn.
1254
1255 memmap=nn[KMG]#ss[KMG]
1256 [KNL,ACPI] Mark specific memory as ACPI data.
1257 Region of memory to be used, from ss to ss+nn.
1258
1259 memmap=nn[KMG]$ss[KMG]
1260 [KNL,ACPI] Mark specific memory as reserved.
1261 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001262 Example: Exclude memory from 0x18690000-0x1869ffff
1263 memmap=64K$0x18690000
1264 or
1265 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001267 memory_corruption_check=0/1 [X86]
1268 Some BIOSes seem to corrupt the first 64k of
1269 memory when doing things like suspend/resume.
1270 Setting this option will scan the memory
1271 looking for corruption. Enabling this will
1272 both detect corruption and prevent the kernel
1273 from using the memory being corrupted.
1274 However, its intended as a diagnostic tool; if
1275 repeatable BIOS-originated corruption always
1276 affects the same memory, you can use memmap=
1277 to prevent the kernel from using that memory.
1278
1279 memory_corruption_check_size=size [X86]
1280 By default it checks for corruption in the low
1281 64k, making this memory unavailable for normal
1282 use. Use this parameter to scan for
1283 corruption in more or less memory.
1284
1285 memory_corruption_check_period=seconds [X86]
1286 By default it checks for corruption every 60
1287 seconds. Use this parameter to check at some
1288 other rate. 0 disables periodic checking.
1289
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001290 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001291 Format: <integer>
1292 range: 0,4 : pattern number
1293 default : 0 <disable>
1294
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 meye.*= [HW] Set MotionEye Camera parameters
1296 See Documentation/video4linux/meye.txt.
1297
Andres Salomon8f368812007-10-12 23:04:06 +02001298 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1299 Multi-Function General Purpose Timers on AMD Geode
1300 platforms.
1301
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001302 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1303 the BIOS has incorrectly applied a workaround. TinyBIOS
1304 version 0.98 is known to be affected, 0.99 fixes the
1305 problem by letting the user disable the workaround.
1306
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 mga= [HW,DRM]
1308
Randy Dunlap1c207f92008-11-19 15:36:16 -08001309 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1310 physical address is ignored.
1311
Mel Gorman6b74ab92008-07-23 21:26:49 -07001312 mminit_loglevel=
1313 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1314 parameter allows control of the logging verbosity for
1315 the additional memory initialisation checks. A value
1316 of 0 disables mminit logging and a level of 4 will
1317 log everything. Information is printed at KERN_DEBUG
1318 so loglevel=8 may also need to be specified.
1319
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320 mousedev.tap_time=
1321 [MOUSE] Maximum time between finger touching and
1322 leaving touchpad surface for touch to be considered
1323 a tap and be reported as a left button click (for
1324 touchpads working in absolute mode only).
1325 Format: <msecs>
1326 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1327 reporting absolute coordinates, such as tablets
1328 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1329 reporting absolute coordinates, such as tablets
1330
1331 mpu401= [HW,OSS]
1332 Format: <io>,<irq>
1333
1334 MTD_Partition= [MTD]
1335 Format: <name>,<region-number>,<size>,<offset>
1336
Randy Dunlapa9913042005-10-23 12:57:11 -07001337 MTD_Region= [MTD] Format:
1338 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339
1340 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001341 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342
Ben Dooks9db829f2008-07-03 11:24:29 +01001343 mtdset= [ARM]
1344 ARM/S3C2412 JIVE boot control
1345
1346 See arch/arm/mach-s3c2412/mach-jive.c
1347
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001349 [HW] Make the MicroTouch USB driver use raw coordinates
1350 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351
1352 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1353
1354 NCR_D700= [HW,SCSI]
1355 See header of drivers/scsi/NCR_D700.c.
1356
1357 ncr5380= [HW,SCSI]
1358
1359 ncr53c400= [HW,SCSI]
1360
1361 ncr53c400a= [HW,SCSI]
1362
1363 ncr53c406a= [HW,SCSI]
1364
1365 ncr53c8xx= [HW,SCSI]
1366
1367 netdev= [NET] Network devices parameters
1368 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1369 Note that mem_start is often overloaded to mean
1370 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001371 This usage is only documented in each driver source
1372 file if at all.
1373
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001374 nf_conntrack.acct=
1375 [NETFILTER] Enable connection tracking flow accounting
1376 0 to disable accounting
1377 1 to enable accounting
1378 Default value depends on CONFIG_NF_CT_ACCT that is
1379 going to be removed in 2.6.29.
1380
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001382 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383
1384 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001385 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386
Trond Myklebusta72b4422006-01-03 09:55:41 +01001387 nfs.callback_tcpport=
1388 [NFS] set the TCP port on which the NFSv4 callback
1389 channel should listen.
1390
Trond Myklebust58df0952006-01-03 09:55:57 +01001391 nfs.idmap_cache_timeout=
1392 [NFS] set the maximum lifetime for idmapper cache
1393 entries.
1394
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001395 nfs.enable_ino64=
1396 [NFS] enable 64-bit inode numbers.
1397 If zero, the NFS client will fake up a 32-bit inode
1398 number for the readdir() and stat() syscalls instead
1399 of returning the full 64-bit number.
1400 The default is to return 64-bit inode numbers.
1401
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001402 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1403 when a NMI is triggered.
1404 Format: [state][,regs][,debounce][,die]
1405
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001406 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001408 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 emulation library even if a 387 maths coprocessor
1410 is present.
1411
Christoph Lameterc1aee212007-05-31 00:40:47 -07001412 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1413 caches in the slab allocator. Saves per-node memory,
1414 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001415
Randy Dunlapa9913042005-10-23 12:57:11 -07001416 noalign [KNL,ARM]
1417
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 noapic [SMP,APIC] Tells the kernel to not make use of any
1419 IOAPICs that may be present in the system.
1420
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421 nobats [PPC] Do not use BATs for mapping kernel lowmem
1422 on "Classic" PPC cores.
1423
1424 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001425
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001426 nodelayacct [KNL] Disable per-task delay accounting
1427
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1429
Paul Mundt6902aa82008-09-21 17:14:42 +09001430 nodsp [SH] Disable hardware DSP at boot time.
1431
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001432 noefi [X86-32,X86-64] Disable EFI runtime services support.
1433
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434 noexec [IA-64]
1435
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001436 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001437 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001439 noexec=off: disable non-executable mappings
1440
1441 noexec32 [X86-64]
1442 This affects only 32-bit executables.
1443 noexec32=on: enable non-executable mappings (default)
1444 read doesn't imply executable mappings
1445 noexec32=off: disable non-executable mappings
1446 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447
Paul Mundt6902aa82008-09-21 17:14:42 +09001448 nofpu [SH] Disable hardware FPU at boot time.
1449
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001450 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001451 register save and restore. The kernel will only save
1452 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453
Andi Kleen191679f2008-01-30 13:33:21 +01001454 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1455
Paul Mundt6902aa82008-09-21 17:14:42 +09001456 nohlt [BUGS=ARM,SH]
Randy Dunlapa9913042005-10-23 12:57:11 -07001457
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001458 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 instruction doesn't work correctly and not to
1460 use it.
1461
1462 nohalt [IA-64] Tells the kernel not to use the power saving
1463 function PAL_HALT_LIGHT when idle. This increases
1464 power-consumption. On the positive side, it reduces
1465 interrupt wake-up latency, which may improve performance
1466 in certain environments such as networked servers or
1467 real-time systems.
1468
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001469 nohz= [KNL] Boottime enable/disable dynamic ticks
1470 Valid arguments: on, off
1471 Default: on
1472
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001473 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474 disable unhandled interrupt sources.
1475
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001476 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001477 broken timer IRQ sources.
1478
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 noisapnp [ISAPNP] Disables ISA PnP code.
1480
1481 noinitrd [RAM] Tells the kernel not to load any configured
1482 initial RAM disk.
1483
1484 nointroute [IA-64]
1485
Tony Luck0aa366f2007-07-20 11:22:30 -07001486 nojitter [IA64] Disables jitter checking for ITC timers.
1487
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001488 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001490 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001491
Suresh Siddha6e1cb382008-07-10 11:16:58 -07001492 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1493
Suresh Siddhaaf9d1382008-07-11 13:11:57 -07001494 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1495 default x2apic cluster mode on platforms
1496 supporting x2apic.
1497
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498 noltlbs [PPC] Do not use large page/tlb entries for kernel
1499 lowmem mapping on PPC40x.
1500
Horms312f1f02006-02-22 09:57:55 +09001501 nomca [IA-64] Disable machine check abort handling
1502
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001503 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001504
Andres Salomon83d73842007-10-12 23:04:06 +02001505 nomfgpt [X86-32] Disable Multi-Function General Purpose
1506 Timer usage (for AMD Geode machines).
1507
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001508 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001509
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001510 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001511 with UP alternatives
1512
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513 noresidual [PPC] Don't use residual data on PReP machines.
1514
Randy Dunlapa9913042005-10-23 12:57:11 -07001515 noresume [SWSUSP] Disables resume and restores original swap
1516 space.
1517
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 no-scroll [VGA] Disables scrollback.
1519 This is required for the Braillex ib80-piezo Braille
1520 reader made by F.H. Papenmeier (Germany).
1521
1522 nosbagart [IA-64]
1523
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001524 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001525
Len Brown61ec7562007-08-16 03:34:22 -04001526 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1527 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528
Dave Jones97842212007-07-15 23:41:05 -07001529 nosoftlockup [KNL] Disable the soft-lockup detector.
1530
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 nosync [HW,M68K] Disables sync negotiation for all devices.
1532
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001533 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534
1535 nousb [USB] Disable the USB subsystem
1536
1537 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001538
Fenghua Yua6c75b862008-03-14 13:57:08 -07001539 nptcg= [IA64] Override max number of concurrent global TLB
1540 purges which is reported from either PAL_VM_SUMMARY or
1541 SAL PALO.
1542
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001543 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1544 one of ['zone', 'node', 'default'] can be specified
1545 This can be set from sysctl after boot.
1546 See Documentation/sysctl/vm.txt for details.
1547
Dave Jonesa61c2d72006-01-07 23:18:19 +00001548 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1549
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001550 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1551 Rather than timing out after 20 ms if an EC
1552 command is not properly ACKed, override the length
1553 of the timeout. We have interrupts disabled while
1554 waiting for the ACK, so if this is set too high
1555 interrupts *may* be lost!
1556
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 opl3= [HW,OSS]
1558 Format: <io>
1559
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 oprofile.timer= [HW]
1561 Use timer interrupt instead of performance counters
1562
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563 osst= [HW,SCSI] SCSI Tape Driver
1564 Format: <buffer_size>,<write_threshold>
1565 See also Documentation/scsi/st.txt.
1566
1567 panic= [KNL] Kernel behaviour on panic
1568 Format: <timeout>
1569
1570 parkbd.port= [HW] Parallel port number the keyboard adapter is
1571 connected to, default is 0.
1572 Format: <parport#>
1573 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1574 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001575 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576
Randy Dunlapa9913042005-10-23 12:57:11 -07001577 parport= [HW,PPT] Specify parallel ports. 0 disables.
1578 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1579 Use 'auto' to force the driver to use any
1580 IRQ/DMA settings detected (the default is to
1581 ignore detected IRQ/DMA settings because of
1582 possible conflicts). You can specify the base
1583 address, IRQ, and DMA settings; IRQ and DMA
1584 should be numbers, or 'auto' (for using detected
1585 settings on that particular port), or 'nofifo'
1586 (to avoid using a FIFO even if it is detected).
1587 Parallel ports are assigned in the order they
1588 are specified on the command line, starting
1589 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590
Randy Dunlapa9913042005-10-23 12:57:11 -07001591 parport_init_mode= [HW,PPT]
1592 Configure VIA parallel port to operate in
1593 a specific mode. This is necessary on Pegasos
1594 computer where firmware has no options for setting
1595 up parallel port mode and sets it to spp.
1596 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597 Format: [spp|ps2|epp|ecp|ecpepp]
1598
Randy Dunlapa9913042005-10-23 12:57:11 -07001599 pas2= [HW,OSS] Format:
1600 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1601
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602 pas16= [HW,SCSI]
1603 See header of drivers/scsi/pas16.c.
1604
Andrew Mortondd287792006-03-23 03:00:57 -08001605 pause_on_oops=
1606 Halt all CPUs after the first oops has been printed for
1607 the specified number of seconds. This is to be used if
1608 your oopses keep scrolling off the screen.
1609
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610 pcbit= [HW,ISDN]
1611
1612 pcd. [PARIDE]
1613 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001614 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001615
Randy Dunlapa9913042005-10-23 12:57:11 -07001616 pci=option[,option...] [PCI] various PCI subsystem options:
Andi Kleenc0115602008-08-22 09:53:39 +02001617 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001618 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001619 the hardware directly. Use this if your machine
1620 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001621 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001622 hardware access methods are allowed. Use this
1623 if you experience crashes upon bootup and you
1624 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001625 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001626 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001627 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001628 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001629 noaer [PCIE] If the PCIEAER kernel config parameter is
1630 enabled, this kernel boot option can be used to
1631 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001632 nodomains [PCI] Disable support for multiple PCI
1633 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001634 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001635 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001636 nomsi [MSI] If the PCI_MSI kernel config parameter is
1637 enabled, this kernel boot option can be used to
1638 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001639 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001640 routing table. These calls are known to be buggy
1641 on several machines and they hang the machine
1642 when used, but on other computers it's the only
1643 way to get the interrupt routing table. Try
1644 this option if the kernel is unable to allocate
1645 IRQs or discover secondary PCI buses on your
1646 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001647 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001648 Use with caution as certain devices share
1649 address decoders between ROMs and other
1650 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001651 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001652 expansion ROMs that do not already have
1653 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001654 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001655 assigned automatically to PCI devices. You can
1656 make the kernel exclude IRQs of your ISA cards
1657 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001658 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001659 of the PIRQ table (normally generated
1660 by the BIOS) if it is outside the
1661 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001662 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001663 useful if the kernel is unable to find your
1664 secondary buses and you want to tell it
1665 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001666 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001667 numbers ourselves, overriding
1668 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001669 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001670 in the BIOS $PIR table. This is needed on
1671 some systems with broken BIOSes, notably
1672 some HP Pavilion N5400 and Omnibook XE3
1673 notebooks. This will have no effect if ACPI
1674 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001675 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001676 or for PCI scanning.
Andi Kleenc0115602008-08-22 09:53:39 +02001677 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001678 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001679 routeirq Do IRQ routing for all PCI devices.
1680 This is normally done in pci_enable_device(),
1681 so this option is a temporary workaround
1682 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001683 skip_isa_align [X86] do not align io start addr, so can
1684 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001685 firmware [ARM] Do not re-enumerate the bus but instead
1686 just use the configuration from the
1687 bootloader. This is currently used on
1688 IXP2000 systems where the bus has to be
1689 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001690 noearly [X86] Don't do any early type 1 scanning.
1691 This might help on some broken boards which
1692 machine check when some devices' config space
1693 is read. But various workarounds are disabled
1694 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001695 bfsort Sort PCI devices into breadth-first order.
1696 This sorting is done to get a device
1697 order compatible with older (<= 2.4) kernels.
1698 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001699 cbiosize=nn[KMG] The fixed amount of bus space which is
1700 reserved for the CardBus bridge's IO window.
1701 The default value is 256 bytes.
1702 cbmemsize=nn[KMG] The fixed amount of bus space which is
1703 reserved for the CardBus bridge's memory
1704 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001705
Chuck Ebberte5665a42008-09-24 20:40:34 -04001706 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1707 Management.
1708 off Disable ASPM.
1709 force Enable ASPM even on devices that claim not to support it.
1710 WARNING: Forcing ASPM on may cause system lockups.
1711
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 pcmv= [HW,PCMCIA] BadgePAD 4
1713
1714 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001715 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716
1717 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1718 boot time.
1719 Format: { 0 | 1 }
1720 See arch/parisc/kernel/pdc_chassis.c
1721
1722 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001723 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724
1725 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001726 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727
1728 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001729 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730
1731 plip= [PPT,NET] Parallel port network link
1732 Format: { parport<nr> | timid | 0 }
1733 See also Documentation/parport.txt.
1734
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001735 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1736 Override pmtimer IOPort with a hex value.
1737 e.g. pmtmr=0x508
1738
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06001739 pnp.debug [PNP]
1740 Enable PNP debug messages. This depends on the
1741 CONFIG_PNP_DEBUG_MESSAGES option.
1742
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743 pnpacpi= [ACPI]
1744 { off }
1745
1746 pnpbios= [ISAPNP]
1747 { on | off | curr | res | no-curr | no-res }
1748
1749 pnp_reserve_irq=
1750 [ISAPNP] Exclude IRQs for the autoconfiguration
1751
1752 pnp_reserve_dma=
1753 [ISAPNP] Exclude DMAs for the autoconfiguration
1754
1755 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001756 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757
1758 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001759 [ISAPNP] Exclude memory regions for the
1760 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001761 Ranges are in pairs (memory base and size).
1762
Jason Baron346e15b2008-08-12 16:46:19 -04001763 dynamic_printk
1764 Enables pr_debug()/dev_dbg() calls if
1765 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1766 be switched on/off via <debugfs>/dynamic_printk/modules
1767
Ingo Molnar45807a12007-07-15 23:40:10 -07001768 print-fatal-signals=
1769 [KNL] debug: print fatal signals
1770 print-fatal-signals=1: print segfault info to
1771 the kernel console.
1772 default: off.
1773
Randy Dunlape84845c2007-07-15 23:40:25 -07001774 printk.time= Show timing data prefixed to each printk message line
1775 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1776
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001778 Format: [schedule,]<number>
1779 Param: "schedule" - profile schedule points.
1780 Param: <number> - step/bucket size as a power of 2 for
1781 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001782 Param: "sleep" - profile D-state sleeping (millisecs).
1783 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001784 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785
Randy Dunlapa9913042005-10-23 12:57:11 -07001786 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 Limit processor to maximum C-state
1788 max_cstate=9 overrides any DMI blacklist limit.
1789
Len Brown41c0d862005-12-28 12:43:51 -05001790 processor.nocst [HW,ACPI]
1791 Ignore the _CST method to determine C-states,
1792 instead using the legacy FADT method
1793
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1795 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001796 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001797
Randy Dunlapa9913042005-10-23 12:57:11 -07001798 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1799 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1801 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001802 psmouse.resetafter= [HW,MOUSE]
1803 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 (0 = never).
1805 psmouse.resolution=
1806 [HW,MOUSE] Set desired mouse resolution, in dpi.
1807 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001808 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001809 0 = disabled, 1 = enabled (default).
1810
1811 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001812 Format:
1813 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814
1815 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001816 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001817
Kay Sieversdc8c8582007-08-15 12:25:38 +02001818 pty.legacy_count=
1819 [KNL] Number of legacy pty's. Overwrites compiled-in
1820 default number.
1821
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001822 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001823
Linus Torvalds1da177e2005-04-16 15:20:36 -07001824 r128= [HW,DRM]
1825
1826 raid= [HW,RAID]
1827 See Documentation/md.txt.
1828
Randy Dunlapa9913042005-10-23 12:57:11 -07001829 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001830 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001831
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001833 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001835 rcupdate.blimit= [KNL,BOOT]
1836 Set maximum number of finished RCU callbacks to process
1837 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001838
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001839 rcupdate.qhimark= [KNL,BOOT]
1840 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001841 RCU callbacks over which batch limiting is disabled.
1842
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001843 rcupdate.qlowmark= [KNL,BOOT]
1844 Set threshold of queued RCU callbacks below which
1845 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001846
Olof Johanssonffdfc402005-09-06 15:17:19 -07001847 rdinit= [KNL]
1848 Format: <full_path>
1849 Run specified binary instead of /init from the ramdisk,
1850 used for early userspace startup. See initrd.
1851
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001852 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001854 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855
Paul Jackson46b6d942008-07-04 10:00:09 -07001856 relax_domain_level=
1857 [KNL, SMP] Set scheduler's default relax_domain_level.
1858 See Documentation/cpusets.txt.
1859
Linus Torvalds1da177e2005-04-16 15:20:36 -07001860 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1861
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001862 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07001863 Format: nn[KMG]
1864 Reserves a hole at the top of the kernel virtual
1865 address space.
1866
Vivek Goyal7e962872006-09-27 01:50:44 -07001867 reset_devices [KNL] Force drivers to reset the underlying device
1868 during initialization.
1869
Randy Dunlapa9913042005-10-23 12:57:11 -07001870 resume= [SWSUSP]
1871 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001872
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001873 resume_offset= [SWSUSP]
1874 Specify the offset from the beginning of the partition
1875 given by "resume=" at which the swap header is located,
1876 in <PAGE_SIZE> units (needed only for swap files).
1877 See Documentation/power/swsusp-and-swap-files.txt
1878
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001879 retain_initrd [RAM] Keep initrd memory after extraction
1880
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881 rhash_entries= [KNL,NET]
1882 Set number of hash buckets for route cache
1883
1884 riscom8= [HW,SERIAL]
1885 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1886
1887 ro [KNL] Mount root device read-only on boot
1888
1889 root= [KNL] Root filesystem
1890
1891 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1892 mount the root filesystem
1893
1894 rootflags= [KNL] Set root filesystem mount option string
1895
1896 rootfstype= [KNL] Set root filesystem type
1897
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001898 rootwait [KNL] Wait (indefinitely) for root device to show up.
1899 Useful for devices that are detected asynchronously
1900 (e.g. USB and MMC devices).
1901
James Morris20510f22007-10-16 23:31:32 -07001902 root_plug.vendor_id=
1903 [ROOTPLUG] Override the default vendor ID
1904
1905 root_plug.product_id=
1906 [ROOTPLUG] Override the default product ID
1907
1908 root_plug.debug=
1909 [ROOTPLUG] Enable debugging output
1910
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911 rw [KNL] Mount root device read-write on boot
1912
1913 S [KNL] Run init in single mode
1914
1915 sa1100ir [NET]
1916 See drivers/net/irda/sa1100_ir.c.
1917
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001919
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1921 Format: <io>[,<timeout>[,<isapnp>]]
1922
1923 scsi_debug_*= [SCSI]
1924 See drivers/scsi/scsi_debug.c.
1925
1926 scsi_default_dev_flags=
1927 [SCSI] SCSI default device flags
1928 Format: <integer>
1929
1930 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1931 Format: <vendor>:<model>:<flags>
1932 (flags are integer value)
1933
Randy Dunlap6af66322007-11-14 16:52:25 -08001934 scsi_logging_level= [SCSI] a bit mask of logging levels
1935 See drivers/scsi/scsi_logging.h for bits. Also
1936 settable via sysctl at dev.scsi.logging_level
1937 (/proc/sys/dev/scsi/logging_level).
1938 There is also a nice 'scsi_logging_level' script in the
1939 S390-tools package, available for download at
1940 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001942 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1943 discovered. async scans them in kernel threads,
1944 allowing boot to proceed. none ignores them, expecting
1945 user space to do the scan.
1946
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947 selinux [SELINUX] Disable or enable SELinux at boot time.
1948 Format: { "0" | "1" }
1949 See security/selinux/Kconfig help text.
1950 0 -- disable.
1951 1 -- enable.
1952 Default value is set via kernel config option.
1953 If enabled at boot time, /selinux/disable can be used
1954 later to disable prior to initial policy load.
1955
James Morris4e5ab4c2006-06-09 00:33:33 -07001956 selinux_compat_net =
1957 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001958 Format: { "0" | "1" }
1959 0 -- use new secmark-based packet controls
1960 1 -- use legacy packet controls
1961 Default value is 0 (preferred).
1962 Value can be changed at runtime via
1963 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001964
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001965 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967 shapers= [NET]
1968 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001969
Yinghai Lub05f78f2008-08-22 01:32:50 -07001970 show_msr= [x86] show boot-time MSR settings
1971 Format: { <integer> }
1972 Show boot-time (BIOS-initialized) MSR settings.
1973 The parameter means the number of CPUs to show,
1974 for example 1 means boot CPU only.
1975
Linus Torvalds1da177e2005-04-16 15:20:36 -07001976 sim710= [SCSI,HW]
1977 See header of drivers/scsi/sim710.c.
1978
1979 simeth= [IA-64]
1980 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001981
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 slram= [HW,MTD]
1983
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001984 slub_debug[=options[,slabs]] [MM, SLUB]
1985 Enabling slub_debug allows one to determine the
1986 culprit if slab objects become corrupted. Enabling
1987 slub_debug can create guard zones around objects and
1988 may poison objects when not in use. Also tracks the
1989 last alloc / free. For more information see
1990 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001991
1992 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001993 Determines the maximum allowed order for slabs.
1994 A high setting may cause OOMs due to memory
1995 fragmentation. For more information see
1996 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001997
1998 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001999 The minimum number of objects per slab. SLUB will
2000 increase the slab order up to slub_max_order to
2001 generate a sufficiently large slab able to contain
2002 the number of objects indicated. The higher the number
2003 of objects the smaller the overhead of tracking slabs
2004 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002005 For more information see Documentation/vm/slub.txt.
2006
2007 slub_min_order= [MM, SLUB]
2008 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002009 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002010 For more information see Documentation/vm/slub.txt.
2011
2012 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002013 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002014 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002015 allocs to different slabs. Debug options disable
2016 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002017 For more information see Documentation/vm/slub.txt.
2018
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019 smart2= [HW]
2020 Format: <io1>[,<io2>[,...,<io8>]]
2021
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002022 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002023 attempt to substitute SMP alternatives once at boot.
2024
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002025 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2026 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2027 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2028 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2029 smsc-ircc2.ircc_irq= [HW] IRQ line
2030 smsc-ircc2.ircc_dma= [HW] DMA channel
2031 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2032 0: Toshiba Satellite 1800 (GP data pin select)
2033 1: Fast pin select (default)
2034 2: ATC IRMode
2035
Linus Torvalds1da177e2005-04-16 15:20:36 -07002036 snd-ad1816a= [HW,ALSA]
2037
2038 snd-ad1848= [HW,ALSA]
2039
2040 snd-ali5451= [HW,ALSA]
2041
2042 snd-als100= [HW,ALSA]
2043
2044 snd-als4000= [HW,ALSA]
2045
2046 snd-azt2320= [HW,ALSA]
2047
2048 snd-cmi8330= [HW,ALSA]
2049
2050 snd-cmipci= [HW,ALSA]
2051
2052 snd-cs4231= [HW,ALSA]
2053
2054 snd-cs4232= [HW,ALSA]
2055
2056 snd-cs4236= [HW,ALSA]
2057
2058 snd-cs4281= [HW,ALSA]
2059
2060 snd-cs46xx= [HW,ALSA]
2061
2062 snd-dt019x= [HW,ALSA]
2063
2064 snd-dummy= [HW,ALSA]
2065
2066 snd-emu10k1= [HW,ALSA]
2067
2068 snd-ens1370= [HW,ALSA]
2069
2070 snd-ens1371= [HW,ALSA]
2071
2072 snd-es968= [HW,ALSA]
2073
2074 snd-es1688= [HW,ALSA]
2075
2076 snd-es18xx= [HW,ALSA]
2077
2078 snd-es1938= [HW,ALSA]
2079
2080 snd-es1968= [HW,ALSA]
2081
2082 snd-fm801= [HW,ALSA]
2083
2084 snd-gusclassic= [HW,ALSA]
2085
2086 snd-gusextreme= [HW,ALSA]
2087
2088 snd-gusmax= [HW,ALSA]
2089
2090 snd-hdsp= [HW,ALSA]
2091
2092 snd-ice1712= [HW,ALSA]
2093
2094 snd-intel8x0= [HW,ALSA]
2095
2096 snd-interwave= [HW,ALSA]
2097
2098 snd-interwave-stb=
2099 [HW,ALSA]
2100
2101 snd-korg1212= [HW,ALSA]
2102
2103 snd-maestro3= [HW,ALSA]
2104
2105 snd-mpu401= [HW,ALSA]
2106
2107 snd-mtpav= [HW,ALSA]
2108
2109 snd-nm256= [HW,ALSA]
2110
2111 snd-opl3sa2= [HW,ALSA]
2112
2113 snd-opti92x-ad1848=
2114 [HW,ALSA]
2115
2116 snd-opti92x-cs4231=
2117 [HW,ALSA]
2118
2119 snd-opti93x= [HW,ALSA]
2120
2121 snd-pmac= [HW,ALSA]
2122
2123 snd-rme32= [HW,ALSA]
2124
2125 snd-rme96= [HW,ALSA]
2126
2127 snd-rme9652= [HW,ALSA]
2128
2129 snd-sb8= [HW,ALSA]
2130
2131 snd-sb16= [HW,ALSA]
2132
2133 snd-sbawe= [HW,ALSA]
2134
2135 snd-serial= [HW,ALSA]
2136
2137 snd-sgalaxy= [HW,ALSA]
2138
2139 snd-sonicvibes= [HW,ALSA]
2140
2141 snd-sun-amd7930=
2142 [HW,ALSA]
2143
2144 snd-sun-cs4231= [HW,ALSA]
2145
2146 snd-trident= [HW,ALSA]
2147
2148 snd-usb-audio= [HW,ALSA,USB]
2149
2150 snd-via82xx= [HW,ALSA]
2151
2152 snd-virmidi= [HW,ALSA]
2153
2154 snd-wavefront= [HW,ALSA]
2155
2156 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002157
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002158 softlockup_panic=
2159 [KNL] Should the soft-lockup detector generate panics.
2160
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2162 See Documentation/sonypi.txt
2163
2164 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002165 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166
2167 spia_io_base= [HW,MTD]
2168 spia_fio_base=
2169 spia_pedr=
2170 spia_peddr=
2171
2172 sscape= [HW,OSS]
2173 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002174
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2176 See Documentation/scsi/st.txt.
2177
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178 sti= [PARISC,HW]
2179 Format: <num>
2180 Set the STI (builtin display/keyboard on the HP-PARISC
2181 machines) console (graphic card) which should be used
2182 as the initial boot-console.
2183 See also comment in drivers/video/console/sticore.c.
2184
2185 sti_font= [HW]
2186 See comment in drivers/video/console/sticore.c.
2187
2188 stifb= [HW]
2189 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2190
Greg Banks42a7fc42007-03-06 01:42:23 -08002191 sunrpc.pool_mode=
2192 [NFS]
2193 Control how the NFS server code allocates CPUs to
2194 service thread pools. Depending on how many NICs
2195 you have and where their interrupts are bound, this
2196 option will affect which CPUs will do NFS serving.
2197 Note: this parameter cannot be changed while the
2198 NFS server is running.
2199
2200 auto the server chooses an appropriate mode
2201 automatically using heuristics
2202 global a single global pool contains all CPUs
2203 percpu one pool for each CPU
2204 pernode one pool for each NUMA node (equivalent
2205 to global on non-NUMA machines)
2206
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002208
Linus Torvalds1da177e2005-04-16 15:20:36 -07002209 switches= [HW,M68k]
2210
2211 sym53c416= [HW,SCSI]
2212 See header of drivers/scsi/sym53c416.c.
2213
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002214 sysrq_always_enabled
2215 [KNL]
2216 Ignore sysrq setting - this boot parameter will
2217 neutralize any effect of /proc/sys/kernel/sysrq.
2218 Useful for debugging.
2219
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220 t128= [HW,SCSI]
2221 See header of drivers/scsi/t128.c.
2222
2223 tdfx= [HW,DRM]
2224
David Brownell77437fd2008-07-23 21:28:33 -07002225 test_suspend= [SUSPEND]
2226 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2227 standby suspend) as the system sleep state to briefly
2228 enter during system startup. The system is woken from
2229 this state using a wakeup-capable RTC alarm.
2230
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231 thash_entries= [KNL,NET]
2232 Set number of hash buckets for TCP connection
2233
Len Brownf8707ec2007-08-12 00:12:54 -04002234 thermal.act= [HW,ACPI]
2235 -1: disable all active trip points in all thermal zones
2236 <degrees C>: override all lowest active trip points
2237
Len Brownc52a7412007-08-14 15:49:32 -04002238 thermal.crt= [HW,ACPI]
2239 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002240 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002241
Len Brownf5487142007-08-12 00:12:44 -04002242 thermal.nocrt= [HW,ACPI]
2243 Set to disable actions on ACPI thermal zone
2244 critical and hot trip points.
2245
Len Brown72b33ef2007-08-12 00:12:17 -04002246 thermal.off= [HW,ACPI]
2247 1: disable ACPI thermal control
2248
Len Browna70cdc52007-08-12 00:12:35 -04002249 thermal.psv= [HW,ACPI]
2250 -1: disable all passive trip points
2251 <degrees C>: override all passive trip points to this value
2252
Len Brown730ff342007-08-12 00:12:26 -04002253 thermal.tzp= [HW,ACPI]
2254 Specify global default ACPI thermal zone polling rate
2255 <deci-seconds>: poll all this frequency
2256 0: no polling (default)
2257
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 tmscsim= [HW,SCSI]
2259 See comment before function dc390_setup() in
2260 drivers/scsi/tmscsim.c.
2261
2262 tp720= [HW,PS2]
2263
2264 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002265 Format:
2266 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2267
Randy Dunlapa9913042005-10-23 12:57:11 -07002268 turbografx.map[2|3]= [HW,JOY]
2269 TurboGraFX parallel port interface
2270 Format:
2271 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 See also Documentation/input/joystick-parport.txt
2273
2274 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2275 See header of drivers/scsi/u14-34f.c.
2276
2277 uart401= [HW,OSS]
2278 Format: <io>,<irq>
2279
2280 uart6850= [HW,OSS]
2281 Format: <io>,<irq>
2282
Alan Stern5f8364b2006-12-05 16:29:55 -05002283 uhci-hcd.ignore_oc=
2284 [USB] Ignore overcurrent events (default N).
2285 Some badly-designed motherboards generate lots of
2286 bogus events, for ports that aren't wired to
2287 anything. Set this parameter to avoid log spamming.
2288 Note that genuine overcurrent events won't be
2289 reported either.
2290
Simon Arlotte3a61b02008-07-19 23:32:54 +01002291 unknown_nmi_panic
2292 [X86-32,X86-64]
2293 Set unknown_nmi_panic=1 early on boot.
2294
Alan Sternb5e795f2007-02-20 15:00:53 -05002295 usbcore.autosuspend=
2296 [USB] The autosuspend time delay (in seconds) used
2297 for newly-detected USB devices (default 2). This
2298 is the time required before an idle device will be
2299 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002300 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002301
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002302 usbcore.usbfs_snoop=
2303 [USB] Set to log all usbfs traffic (default 0 = off).
2304
2305 usbcore.blinkenlights=
2306 [USB] Set to cycle leds on hubs (default 0 = off).
2307
2308 usbcore.old_scheme_first=
2309 [USB] Start with the old device initialization
2310 scheme (default 0 = off).
2311
2312 usbcore.use_both_schemes=
2313 [USB] Try the other device initialization scheme
2314 if the first one fails (default 1 = enabled).
2315
2316 usbcore.initial_descriptor_timeout=
2317 [USB] Specifies timeout for the initial 64-byte
2318 USB_REQ_GET_DESCRIPTOR request in milliseconds
2319 (default 5000 = 5.0 seconds).
2320
Linus Torvalds1da177e2005-04-16 15:20:36 -07002321 usbhid.mousepoll=
2322 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002323
Paul Jackson200001e2008-06-25 05:44:46 -07002324 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2325 kernel's map of available physical RAM.
2326
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002327 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002328 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002329 vdso=1: enable VDSO (default)
2330 vdso=0: disable VDSO mapping
2331
Roland McGrathaf65d642008-01-30 13:30:43 +01002332 vdso32= [X86-32,X86-64]
2333 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2334 vdso32=1: enable 32-bit VDSO (default)
2335 vdso32=0: disable 32-bit VDSO mapping
2336
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002337 vector= [IA-64,SMP]
2338 vector=percpu: enable percpu vector domain
2339
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340 video= [FB] Frame buffer configuration
2341 See Documentation/fb/modedb.txt.
2342
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002343 vga= [BOOT,X86-32] Select a particular video mode
Uwe Hermann71cced62008-10-20 09:32:21 -07002344 See Documentation/x86/i386/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002345 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002346 Use vga=ask for menu.
2347 This is actually a boot loader parameter; the value is
2348 passed to the kernel using a special protocol.
2349
Randy Dunlapa9913042005-10-23 12:57:11 -07002350 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351 size of <nn>. This can be used to increase the
2352 minimum size (128MB on x86). It can also be used to
2353 decrease the size and leave more room for directly
2354 mapped kernel RAM.
2355
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002356 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2357 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002358
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002359 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2360 Format: <command>
2361
2362 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2363 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002364
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365 waveartist= [HW,OSS]
2366 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002367
Linus Torvalds1da177e2005-04-16 15:20:36 -07002368 wd33c93= [HW,SCSI]
2369 See header of drivers/scsi/wd33c93.c.
2370
2371 wd7000= [HW,SCSI]
2372 See header of drivers/scsi/wd7000.c.
2373
2374 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002375 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376
2377 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2378 xd_geo= See header of drivers/block/xd.c.
2379
2380 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002381 Format:
2382 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002383
Andi Kleena62eaf12006-02-16 23:41:58 +01002384 norandmaps Don't use address space randomization
2385 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2386
Randy Dunlapa9913042005-10-23 12:57:11 -07002387______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388
2389TODO:
2390
2391 Add documentation for ALSA options.
2392 Add more DRM drivers.