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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Stefan Richtera901ebb2006-04-01 01:43:18 +020020This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
Stefan Richter6585fa82006-04-01 01:44:30 +020027The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100033 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020037 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080039 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070040 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070048 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070052 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070061 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070062 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070065 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070068 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070072 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
James Morris20510f22007-10-16 23:31:32 -070079 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070084 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090087 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070090 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700100 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
104
105In addition, the following text indicates that the option:
106
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
110
111Parameters denoted with BOOT are actually interpreted by the boot
112loader, and have no meaning to the kernel directly.
113Do not modify the syntax of boot loader parameters without extreme
114need or coordination with <Documentation/i386/boot.txt>.
115
Karsten Weiss55588702007-02-13 13:26:21 +0100116There are also arch-specific kernel-parameters not documented here.
117See for example <Documentation/x86_64/boot-options.txt>.
118
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120a trailing = on the name of any parameter states that that parameter will
121be entered as an environment variable, whereas its absence indicates that
122it will appear as a kernel argument readable via /proc/cmdline by programs
123running once the system is up.
124
jens m. noedler9c4751f2006-09-29 02:00:27 -0700125The number of kernel parameters is not limited, but the length of the
126complete command line (parameters including spaces etc.) is limited to
127a fixed number of characters. This limit depends on the architecture
128and is between 256 and 4096 characters. It is defined in the file
129./include/asm/setup.h as COMMAND_LINE_SIZE.
130
131
Bernhard Walle03d926f2007-03-06 02:29:44 -0800132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
Randy Dunlapa9913042005-10-23 12:57:11 -0700134 Format: { force | off | ht | strict | noirq }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700139 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 strictly ACPI specification compliant.
141
Randy Dunlap53471122008-03-12 18:10:51 -0400142 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
Len Browna1fdcc02007-03-11 03:26:14 -0400144 acpi_apic_instance= [ACPI, IOAPIC]
145 Format: <int>
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400148 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400149
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 acpi_sleep= [HW,ACPI] Sleep options
Shaohua Libdfe6b72008-07-23 21:28:41 -0700151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
Pavel Machek23b168d2008-02-05 19:27:12 +0100152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
Shaohua Libdfe6b72008-07-23 21:28:41 -0700155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
Rafael J. Wysockid8f3de02008-06-12 23:24:06 +0200157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
160 used by default).
Randy Dunlapa9913042005-10-23 12:57:11 -0700161
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Randy Dunlapa9913042005-10-23 12:57:11 -0700163 Format: { level | edge | high | low }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
Randy Dunlapa9913042005-10-23 12:57:11 -0700165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
167 default in APIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
Randy Dunlapa9913042005-10-23 12:57:11 -0700169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
171 default in PIC mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
Randy Dunlapa9913042005-10-23 12:57:11 -0700173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
174 use by PCI
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 Format: <irq>,<irq>...
176
Randy Dunlapa9913042005-10-23 12:57:11 -0700177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 Format: <irq>,<irq>...
179
Len Brown67effe82007-07-26 00:50:06 -0400180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
181
Len Browna1f9e652006-01-25 23:47:36 -0500182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
184
Len Brownae00d812007-05-29 18:43:33 -0400185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189
190 acpi_serialize [HW,ACPI] force serialization of AML methods
191
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
Andi Kleenfa18f472006-11-14 16:57:46 +0100195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
198 HPET
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199
Zhang Ruif9891062007-04-24 13:53:22 +0800200 acpi.debug_layer= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700202 Each bit of the <int> indicates an ACPI debug layer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
Zhang Ruif9891062007-04-24 13:53:22 +0800217 acpi.debug_level= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 Format: <int>
Randy Dunlapa9913042005-10-23 12:57:11 -0700219 Each bit of the <int> indicates an ACPI debug level,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
Zhang Ruif9891062007-04-24 13:53:22 +0800222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
234
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700235 acpi_pm_good [X86-32,X86-64]
john stultz5d0cf412006-06-26 00:25:12 -0700236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
239
Chuck Ebbertc99c1082007-07-27 10:46:20 +1000240 agp= [AGP]
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
245
Chuck Ebbert66759a02005-09-12 18:49:25 +0200246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
Randy Dunlapa9913042005-10-23 12:57:11 -0700248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
Chuck Ebbert66759a02005-09-12 18:49:25 +0200250 The kernel tries to set a reasonable default.
251
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
255
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 ad1848= [HW,OSS]
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
258
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 advansys= [HW,SCSI]
260 See header of drivers/scsi/advansys.c.
261
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
264
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700268
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 aha152x= [HW,SCSI]
270 See Documentation/scsi/aha152x.txt.
271
272 aha1542= [HW,SCSI]
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
274
275 aic7xxx= [HW,SCSI]
276 See Documentation/scsi/aic7xxx.txt.
277
278 aic79xx= [HW,SCSI]
279 See Documentation/scsi/aic79xx.txt.
280
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
283 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
286 domain)
287 amd_iommu_size= [HW,X86-64]
288 Define the size of the aperture for the AMD IOMMU
289 driver. Possible values are:
290 '32M', '64M' (default), '128M', '256M', '512M', '1G'
291
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 amijoy.map= [HW,JOY] Amiga joystick support
293 Map of devices attached to JOY0DAT and JOY1DAT
294 Format: <a>,<b>
295 See also Documentation/kernel/input/joystick.txt
296
297 analog.map= [HW,JOY] Analog joystick and gamepad support
298 Specifies type or capabilities of an analog joystick
299 connected to one of 16 gameports
300 Format: <type1>,<type2>,..<type16>
301
Randy Dunlapa9913042005-10-23 12:57:11 -0700302 apc= [HW,SPARC]
303 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 Format: noidle
305 Disable APC CPU standby support. SPARCstation-Fox does
306 not play well with APC CPU idle - disable it if you have
307 APC and your system crashes randomly.
308
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700309 apic= [APIC,i386] Advanced Programmable Interrupt Controller
310 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 Format: { quiet (default) | verbose | debug }
312 Change the amount of debugging information output
313 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700314
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700316 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
319 Format: <io>,<irq>,<nodeID>
320
321 ataflop= [HW,M68k]
322
323 atarimouse= [HW,MOUSE] Atari Mouse
324
325 atascsi= [HW,SCSI] Atari SCSI
326
327 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
328 EzKey and similar keyboards
329
330 atkbd.reset= [HW] Reset keyboard during initialization
331
Randy Dunlapa9913042005-10-23 12:57:11 -0700332 atkbd.set= [HW] Select keyboard code set
333 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
335 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
336 keyboards
337
338 atkbd.softraw= [HW] Choose between synthetic and real raw mode
339 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700340
341 atkbd.softrepeat= [HW]
342 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343
344 autotest [IA64]
345
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 baycom_epp= [HW,AX25]
347 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700348
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
350 Format: <io>,<mode>
351 See header of drivers/net/hamradio/baycom_par.c.
352
Randy Dunlapa9913042005-10-23 12:57:11 -0700353 baycom_ser_fdx= [HW,AX25]
354 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 Format: <io>,<irq>,<mode>[,<baud>]
356 See header of drivers/net/hamradio/baycom_ser_fdx.c.
357
Randy Dunlapa9913042005-10-23 12:57:11 -0700358 baycom_ser_hdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 Format: <io>,<irq>,<mode>
361 See header of drivers/net/hamradio/baycom_ser_hdx.c.
362
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700363 boot_delay= Milliseconds to delay each printk during boot.
364 Values larger than 10 seconds (10000) are changed to
365 no delay (0).
366 Format: integer
367
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700368 bootmem_debug [KNL] Enable bootmem allocator debug messages.
369
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700371 bttv.radio= Most important insmod options are available as
372 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
374 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
375
376 BusLogic= [HW,SCSI]
377 See drivers/scsi/BusLogic.c, comment before function
378 BusLogic_ParseDriverOptions().
379
380 c101= [NET] Moxa C101 synchronous serial card
381
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700382 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 Sometimes CPU hardware bugs make them report the cache
384 size incorrectly. The kernel will attempt work arounds
385 to fix known problems, but for some CPUs it is not
386 possible to determine what the correct size should be.
387 This option provides an override for these situations.
388
Ahmed S. Darwish076c54c2008-03-06 18:09:10 +0200389 security= [SECURITY] Choose a security module to enable at boot.
390 If this boot parameter is not specified, only the first
391 security module asking for security registration will be
392 loaded. An invalid security module name will be treated
393 as if no module has been chosen.
394
James Morris20510f22007-10-16 23:31:32 -0700395 capability.disable=
396 [SECURITY] Disable capabilities. This would normally
397 be used only if an alternative security model is to be
398 configured. Potentially dangerous and should only be
399 used if you are entirely sure of the consequences.
400
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100401 ccw_timeout_log [S390]
402 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403
Paul Menage8bab8dd2008-04-04 14:29:57 -0700404 cgroup_disable= [KNL] Disable a particular controller
405 Format: {name of the controller(s) to disable}
406 {Currently supported controllers - "memory"}
407
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 checkreqprot [SELINUX] Set initial checkreqprot flag value.
409 Format: { "0" | "1" }
410 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700411 0 -- check protection applied by kernel (includes
412 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 1 -- check protection requested by application.
414 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700415 Value can be changed at runtime via
416 /selinux/checkreqprot.
417
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100418 cio_ignore= [S390]
419 See Documentation/s390/CommonIO for details.
420
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700421 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700422 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200423 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700424 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200425 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 Format: { pit | tsc | cyclone | pmtmr }
427
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700428 clocksource= [GENERIC_TIME] Override the default clocksource
429 Format: <string>
430 Override the default clocksource and use the clocksource
431 with the name specified.
432 Some clocksource names to choose from, depending on
433 the platform:
434 [all] jiffies (this is the base, fallback clocksource)
435 [ACPI] acpi_pm
436 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
437 pxa_timer,timer3,32k_counter,timer0_1
438 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700439 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700440 scx200_hrt on Geode; cyclone on IBM x440
441 [MIPS] MIPS
442 [PARISC] cr16
443 [S390] tod
444 [SH] SuperH
445 [SPARC64] tick
446 [X86-64] hpet,tsc
447
Andi Kleenac72e782008-01-30 13:33:21 +0100448 clearcpuid=BITNUM [X86]
449 Disable CPUID feature X for the kernel. See
450 include/asm-x86/cpufeature.h for the valid bit numbers.
451 Note the Linux specific bits are not necessarily
452 stable over kernel options, but the vendor specific
453 ones should be.
454 Also note that user programs calling CPUID directly
455 or using the feature without checking anything
456 will still see it. This just prevents it from
457 being used by the kernel or shown in /proc/cpuinfo.
458 Also note the kernel might malfunction if you disable
459 some critical bits.
460
Arjan van de Vena25bd942008-01-30 13:33:08 +0100461 code_bytes [IA32/X86_64] How many bytes of object code to print
462 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100463 Range: 0 - 8192
464 Default: 64
465
Andi Kleenf9262c12006-03-08 17:57:25 -0800466 disable_8254_timer
467 enable_8254_timer
468 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
469 over the 8254 in addition to over the IO-APIC. The
470 kernel tries to set a sensible default.
471
Thomas Gleixnerb17530b2007-10-19 20:35:02 +0200472 hpet= [X86-32,HPET] option to control HPET usage
473 Format: { enable (default) | disable | force }
474 disable: disable HPET and use PIT instead
Carlos Corbachod79a5f82007-10-19 18:51:27 +0100475 force: allow force enabled of undocumented chips (ICH4,
476 VIA, nVidia)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700479 Format:
480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481
482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
483 Format: <io>[,<irq>]
484
Randy Dunlapa9913042005-10-23 12:57:11 -0700485 com90xx= [HW,NET]
486 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 Format: <io>[,<irq>[,<memstart>]]
488
489 condev= [HW,S390] console device
490 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700491
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 console= [KNL] Output console device and options.
493
494 tty<n> Use the virtual console device <n>.
495
496 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800497 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800499 the form "bbbbpnf", where "bbbb" is the baud rate,
500 "p" is parity ("n", "o", or "e"), "n" is number of
501 bits, and "f" is flow control ("r" for RTS or
502 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800504 See Documentation/serial-console.txt for more
505 information. See
506 Documentation/networking/netconsole.txt for an
507 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700509 uart[8250],io,<addr>[,options]
510 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 Start an early, polled-mode console on the 8250/16550
512 UART at the specified I/O port or MMIO address,
513 switching to the matching ttyS device later. The
514 options are the same as for ttyS, above.
515
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700516 If the device connected to the port is not a TTY but a braille
517 device, prepend "brl," before the device type, for instance
518 console=brl,ttyS0
519 For now, only VisioBraille is supported.
520
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700521 earlycon= [KNL] Output early console device and options.
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address.
526 The options are the same as for ttyS, above.
527
Andres Salomon8f4ce8c2007-10-18 03:04:50 -0700528 no_console_suspend
529 [HW] Never suspend the console
530 Disable suspending of consoles during suspend and
531 hibernate operations. Once disabled, debugging
532 messages can reach various consoles while the rest
533 of the system is being put to sleep (ie, while
534 debugging driver suspend/resume hooks). This may
535 not work reliably with all consoles, but is known
536 to work with serial and VGA consoles.
537
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700539 Format:
540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700542 crashkernel=nn[KMG]@ss[KMG]
543 [KNL] Reserve a chunk of physical memory to
544 hold a kernel to switch to with kexec on panic.
545
Bernhard Wallefb391592007-10-18 23:41:02 -0700546 crashkernel=range1:size1[,range2:size2,...][@offset]
547 [KNL] Same as above, but depends on the memory
548 in the running system. The syntax of range is
549 start-[end] where start and end are both
550 a memory unit (amount[KMG]). See also
551 Documentation/kdump/kdump.txt for a example.
552
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 cs4232= [HW,OSS]
554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
555
556 cs89x0_dma= [HW,NET]
557 Format: <dma>
558
559 cs89x0_media= [HW,NET]
560 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700561
Randy Dunlapa9913042005-10-23 12:57:11 -0700562 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 See header of drivers/s390/block/dasd_devmap.c.
564
565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
566 (one device per port)
567 Format: <port#>,<type>
568 See also Documentation/input/joystick-parport.txt
569
570 debug [KNL] Enable kernel debugging (events log level).
571
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700572 debug_locks_verbose=
573 [KNL] verbose self-tests
574 Format=<0|1>
575 Print debugging info while doing the locking API
576 self-tests.
577 We default to 0 (no extra messages), setting it to
578 1 will print _a lot_ more information - normally
579 only useful to kernel developers.
580
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700581 debug_objects [KNL] Enable object debugging
582
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200583 debugpat [X86] Enable PAT debugging
584
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200585 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 Format: <area>[,<node>]
587 See also Documentation/networking/decnet.txt.
588
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000589 vt.default_blu= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700590 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
591 Change the default blue palette of the console.
592 This is a 16-member array composed of values
593 ranging from 0-255.
594
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000595 vt.default_grn= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700596 Format: <green0>,<green1>,<green2>,...,<green15>
597 Change the default green palette of the console.
598 This is a 16-member array composed of values
599 ranging from 0-255.
600
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000601 vt.default_red= [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700602 Format: <red0>,<red1>,<red2>,...,<red15>
603 Change the default red palette of the console.
604 This is a 16-member array composed of values
605 ranging from 0-255.
606
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000607 vt.default_utf8=
608 [VT]
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700609 Format=<0|1>
610 Set system-wide default UTF-8 mode for all tty's.
Samuel Thibaultecb77fa2008-01-03 16:17:54 +0000611 Default is 1, i.e. UTF-8 mode is enabled for all
612 newly opened terminals.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700613
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614 dhash_entries= [KNL]
615 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700616
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 digi= [HW,SERIAL]
618 IO parameters + enable/disable command.
619
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/digiepca.txt.
623
Yinghai Lu95ffa242008-04-29 03:52:33 -0700624 disable_mtrr_cleanup [X86]
625 enable_mtrr_cleanup [X86]
626 The kernel tries to adjust MTRR layout from continuous
627 to discrete, to make X server driver able to add WB
628 entry later. This parameter enables/disables that.
629
630 mtrr_chunk_size=nn[KMG] [X86]
631 used for mtrr cleanup. It is largest continous chunk
632 that could hold holes aka. UC entries.
633
634 mtrr_gran_size=nn[KMG] [X86]
Yinghai Lu12031a62008-05-02 02:40:22 -0700635 Used for mtrr cleanup. It is granularity of mtrr block.
636 Default is 1.
637 Large value could prevent small alignment from
638 using up MTRRs.
639
640 mtrr_spare_reg_nr=n [X86]
641 Format: <integer>
642 Range: 0,7 : spare reg number
643 Default : 1
644 Used for mtrr cleanup. It is spare mtrr entries number.
645 Set to 2 or more if your graphical card needs more.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700646
Yinghai Lu093af8d2008-01-30 13:33:32 +0100647 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
652
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 dmasound= [HW,OSS] Sound subsystem buffers
654
655 dscc4.setup= [NET]
656
657 dtc3181e= [HW,SCSI]
658
Robin Getz0ae53642007-10-09 17:24:49 +0800659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 earlyprintk=vga
661 earlyprintk=serial[,ttySn[,baudrate]]
662
Randy Dunlapa9913042005-10-23 12:57:11 -0700663 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 takes over.
665
666 Only vga or serial at a time, not both.
667
668 Currently only ttyS0 and ttyS1 are supported.
669
670 Interaction with the standard serial driver is not
671 very good.
672
673 The VGA output is eventually overwritten by the real
674 console.
675
676 eata= [HW,SCSI]
677
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700679 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 eisa_irq_edge= [PARISC,HW]
682 See header of drivers/parisc/eisa.c.
683
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700684 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700686 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687
688 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700690 See Documentation/block/as-iosched.txt and
691 Documentation/block/deadline-iosched.txt for details.
692
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700693 elfcorehdr= [X86-32, X86_64]
Randy Dunlapa9913042005-10-23 12:57:11 -0700694 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800695 image elf header. Generally kexec loader will
696 pass this option to capture kernel.
697 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
699 enforcing [SELINUX] Set initial enforcing status.
700 Format: {"0" | "1"}
701 See security/selinux/Kconfig help text.
702 0 -- permissive (log only, no denials).
703 1 -- enforcing (deny and log).
704 Default value is 0.
705 Value can be changed at runtime via /selinux/enforce.
706
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 es1371= [HW,OSS]
708 Format: <spdif>,[<nomix>,[<amplifier>]]
709 See also header of sound/oss/es1371.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700710
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 ether= [HW,NET] Ethernet cards parameters
712 This option is obsoleted by the "netdev=" option, which
713 has equivalent usage. See its documentation for details.
714
715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
716 Format: <io>[,<irq>]
717
Akinobu Mitade1ba092006-12-08 02:39:42 -0800718 failslab=
719 fail_page_alloc=
720 fail_make_request=[KNL]
721 General fault injection mechanism.
722 Format: <interval>,<probability>,<space>,<times>
723 See also /Documentation/fault-injection/.
724
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 fd_mcs= [HW,SCSI]
726 See header of drivers/scsi/fd_mcs.c.
727
728 fdomain= [HW,SCSI]
729 See header of drivers/scsi/fdomain.c.
730
731 floppy= [HW]
732 See Documentation/floppy.txt.
733
Alex Chiangf13ae302008-05-08 14:03:23 -0600734 force_pal_cache_flush
735 [IA-64] Avoid check_sal_cache_flush which may hang on
736 buggy SAL_CACHE_FLUSH implementations. Using this
737 parameter will force ia64_sal_cache_flush to call
738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 gamecon.map[2|3]=
741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
742 support via parallel port (up to 5 devices per port)
743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
744 See also Documentation/input/joystick-parport.txt
745
746 gamma= [HW,DRM]
747
Yinghai Luaaf23042008-01-30 13:33:09 +0100748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
749 Format: off | on
750 default: on
751
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 gdth= [HW,SCSI]
753 See header of drivers/scsi/gdth.c.
754
755 gpt [EFI] Forces disk with valid GPT signature but
756 invalid Protective MBR to be treated as GPT.
757
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 gvp11= [HW,SCSI]
759
760 hashdist= [KNL,NUMA] Large hashes allocated during boot
761 are distributed across NUMA nodes. Defaults on
762 for IA-64, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700763 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764
765 hcl= [IA-64] SGI's Hardware Graph compatibility layer
766
767 hd= [EIDE] (E)IDE hard drive subsystem geometry
768 Format: <cyl>,<head>,<sect>
769
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
771 size of <nn>. This works even on boxes that have no
772 highmem otherwise. This also works to reduce highmem
773 size on bigger boxes.
774
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800775 highres= [KNL] Enable/disable high resolution timer mode.
776 Valid parameters: "on", "off"
777 Default: "on"
778
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 hisax= [HW,ISDN]
780 See Documentation/isdn/README.HiSax.
781
Andi Kleenb4718e62008-07-23 21:27:51 -0700782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700784 On x86-64 and powerpc, this option can be specified
785 multiple times interleaved with hugepages= to reserve
786 huge pages of different sizes. Valid pages sizes on
787 x86-64 are 2M (when the CPU supports "pse") and 1G
788 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700789 Note that 1GB pages can only be allocated at boot time
790 using hugepages= and not freed afterwards.
Nick Piggine11bfbf2008-07-23 21:27:52 -0700791 default_hugepagesz=
792 [same as hugepagesz=] The size of the default
793 HugeTLB page size. This is the size represented by
794 the legacy /proc/ hugepages APIs, used for SHM, and
795 default size when mounting hugetlbfs filesystems.
796 Defaults to the default architecture's huge page size
797 if not specified.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798
Paul Mundt6902aa82008-09-21 17:14:42 +0900799 hlt [BUGS=ARM,SH]
800
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200802 i8042.dumbkbd [HW] Pretend that controller can only read data from
803 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 (Don't attempt to blink the leds)
805 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500806 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400807 i8042.noloop [HW] Disable the AUX Loopback command while probing
808 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 i8042.nomux [HW] Don't check presence of an active multiplexing
810 controller
811 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
812 controllers
813 i8042.panicblink=
814 [HW] Frequency with which keyboard LEDs should blink
815 when kernel panics (default is 0.5 sec)
816 i8042.reset [HW] Reset the controller during init and cleanup
817 i8042.unlock [HW] Unlock (ignore) the keylock
818
819 i810= [HW,DRM]
820
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700821 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
822 indicates that the driver is running on unsupported
823 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
825 does not match list of supported models.
826 i8k.power_status
827 [HW] Report power status in /proc/i8k
828 (disabled by default)
829 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
830 capability is set.
831
832 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
833 See Documentation/mca.txt.
834
835 icn= [HW,ISDN]
836 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
837
838 ide= [HW] (E)IDE subsystem
Greg Kroah-Hartmana594eeb2008-04-18 00:46:20 +0200839 Format: ide=nodma or ide=doubler
Randy Dunlap1c10e932008-03-07 21:53:50 +0100840 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
Randy Dunlap1c10e932008-03-07 21:53:50 +0100843 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844
Andi Kleenf039b752007-05-02 19:27:12 +0200845 idle= [X86]
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800846 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Andi Kleenf039b752007-05-02 19:27:12 +0200847 Poll forces a polling idle loop that can slightly improves the performance
848 of waking up a idle CPU, but will use a lot of power and make the system
849 run hot. Not recommended.
850 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
851 to not use it because it doesn't save as much power as a normal idle
852 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
853 as idle=poll.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800854 idle=halt. Halt is forced to be used for CPU idle.
855 In such case C2/C3 won't be used again.
Zhao Yakuida5e09a2008-06-24 18:01:09 +0800856 idle=nomwait. Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700857
Denis Cheng594765a2008-02-06 02:57:49 +0100858 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
859 Claim all unknown PCI IDE storage controllers.
860
Ingo Molnar792908222006-12-06 20:40:51 -0800861 ignore_loglevel [KNL]
862 Ignore loglevel setting - this will print /all/
863 kernel messages to the console. Useful for debugging.
864
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 ihash_entries= [KNL]
866 Set number of hash buckets for inode cache.
867
868 in2000= [HW,SCSI]
869 See header of drivers/scsi/in2000.c.
870
871 init= [KNL]
872 Format: <full_path>
873 Run specified binary instead of /sbin/init as init
874 process.
875
876 initcall_debug [KNL] Trace initcalls as they are executed. Useful
877 for working out where the kernel is dying during
878 startup.
879
880 initrd= [BOOT] Specify the location of the initial ramdisk
881
882 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
883 Format: <irq>
884
885 inttest= [IA64]
886
Pavel Machekb552da82008-03-19 15:58:11 +0100887 iommu= [x86]
888 off
889 force
890 noforce
891 biomerge
892 panic
893 nopanic
894 merge
895 nomerge
896 forcesac
897 soft
898
899
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700900 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
901 off
902 Disable intel iommu driver.
903 igfx_off [Default Off]
904 By default, gfx is mapped as normal device. If a gfx
905 device has a dedicated DMAR unit, the DMAR unit is
906 bypassed by not enabling DMAR with this option. In
907 this case, gfx device will use physical address for
908 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700909 forcedac [x86_64]
910 With this option iommu will not optimize to look
911 for io virtual address below 32 bit forcing dual
912 address cycle on pci bus for cards supporting greater
913 than 32 bit addressing. The default is to look
914 for translation below 32 bit and if not available
915 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800916 strict [Default Off]
917 With this option on every unmap_single operation will
918 result in a hardware IOTLB flush operation as opposed
919 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700920
Rene Hermanb02aae92008-01-30 13:30:05 +0100921 io_delay= [X86-32,X86-64] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100922 0x80
923 Standard port 0x80 based delay
924 0xed
925 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +0100926 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100927 Simple two microseconds delay
928 none
929 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +0100930
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 io7= [HW] IO7 for Marvel based alpha systems
932 See comment before marvel_specify_io7 in
933 arch/alpha/kernel/core_marvel.c.
934
935 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -0400936 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937
938 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700939 See comment before ip2_setup() in
940 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941
942 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
943 See header of drivers/scsi/ips.c.
944
Simon Horman72c4a132006-09-13 19:57:18 -0700945 ports= [IP_VS_FTP] IPVS ftp helper module
946 Default is 21.
947 Up to 8 (IP_VS_APP_MAX_PORTS) ports
948 may be specified.
949 Format: <port>,<port>....
950
Alan Cox200803d2005-06-28 20:45:18 -0700951 irqfixup [HW]
952 When an interrupt is not handled search all handlers
953 for it. Intended to get systems with badly broken
954 firmware running.
955
956 irqpoll [HW]
957 When an interrupt is not handled search all handlers
958 for it. Also check all handlers each timer
959 interrupt. Intended to get systems with badly broken
960 firmware running.
961
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -0700963 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964
965 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -0800966 Format:
967 <cpu number>,...,<cpu number>
968 or
969 <cpu number>-<cpu number> (must be a positive range in ascending order)
970 or a mixture
971 <cpu number>,...,<cpu number>-<cpu number>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 This option can be used to specify one or more CPUs
973 to isolate from the general SMP balancing and scheduling
974 algorithms. The only way to move a process onto or off
975 an "isolated" CPU is via the CPU affinity syscalls.
976 <cpu number> begins at 0 and the maximum value is
977 "number of CPUs in system - 1".
978
979 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -0700980 alternative -- manually setting the CPU mask of all
981 tasks in the system -- can cause problems and
982 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983
Randy Dunlapa9913042005-10-23 12:57:11 -0700984 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985
986 js= [HW,JOY] Analog joystick
987 See Documentation/input/joystick.txt.
988
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700989 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -0700990 specifies the amount of memory usable by the kernel
991 for non-movable allocations. The requested amount is
992 spread evenly throughout all nodes in the system. The
993 remaining memory in each node is used for Movable
994 pages. In the event, a node is too small to have both
995 kernelcore and Movable pages, kernelcore pages will
996 take priority and other nodes will have a larger number
997 of kernelcore pages. The Movable zone is used for the
998 allocation of pages that may be reclaimed or moved
999 by the page migration subsystem. This means that
1000 HugeTLB pages may not be allocated from this zone.
1001 Note that allocations like PTEs-from-HighMem still
1002 use the HighMem zone if it exists, and the Normal
1003 zone if it does not.
1004
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001005 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
Mel Gorman7e63efe2007-07-17 04:03:15 -07001006 is similar to kernelcore except it specifies the
1007 amount of memory used for migratable allocations.
1008 If both kernelcore and movablecore is specified,
1009 then kernelcore will be at *least* the specified
1010 value but may be more. If movablecore on its own
1011 is specified, the administrator must be careful
1012 that the amount of memory usable for all allocations
1013 is not too small.
1014
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015 keepinitrd [HW,ARM]
1016
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001017 kstack=N [X86-32,X86-64] Print N words from the kernel stack
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 in oops dumps.
1019
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001020 kgdboc= [HW] kgdb over consoles.
1021 Requires a tty driver that supports console polling.
1022 (only serial suported for now)
1023 Format: <serial_device>[,baud]
1024
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025 l2cr= [PPC]
1026
Robert Brosea78bfbf2008-03-29 07:20:23 +11001027 l3cr= [PPC]
1028
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001029 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001030 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001032 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001033 C2 power state.
1034
FD Camifcb71f62008-01-06 19:08:56 +01001035 libata.dma= [LIBATA] DMA control
1036 libata.dma=0 Disable all PATA and SATA DMA
1037 libata.dma=1 PATA and SATA Disk DMA only
1038 libata.dma=2 ATAPI (CDROM) DMA only
1039 libata.dma=4 Compact Flash DMA only
1040 Combinations also work, so libata.dma=3 enables DMA
1041 for disks and CDROMs, but not CFs.
1042
Dave Jones78e70c22007-09-27 11:50:13 -04001043 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1044 when set.
1045 Format: <int>
1046
Tejun Heo33267322008-02-13 09:15:09 +09001047 libata.force= [LIBATA] Force configurations. The format is comma
1048 separated list of "[ID:]VAL" where ID is
1049 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1050 matching port, link or device. Basically, it matches
1051 the ATA ID string printed on console by libata. If
1052 the whole ID part is omitted, the last PORT and DEVICE
1053 values are used. If ID hasn't been specified yet, the
1054 configuration applies to all ports, links and devices.
1055
1056 If only DEVICE is omitted, the parameter applies to
1057 the port and all links and devices behind it. DEVICE
1058 number of 0 either selects the first device or the
1059 first fan-out link behind PMP device. It does not
1060 select the host link. DEVICE number of 15 selects the
1061 host link and device attached to it.
1062
1063 The VAL specifies the configuration to force. As long
1064 as there's no ambiguity shortcut notation is allowed.
1065 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1066 The following configurations can be forced.
1067
1068 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1069 Any ID with matching PORT is used.
1070
1071 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1072
1073 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1074 udma[/][16,25,33,44,66,100,133] notation is also
1075 allowed.
1076
1077 * [no]ncq: Turn on or off NCQ.
1078
Tejun Heo05944bd2008-08-13 20:19:09 +09001079 * nohrst, nosrst, norst: suppress hard, soft
1080 and both resets.
1081
Tejun Heo33267322008-02-13 09:15:09 +09001082 If there are multiple matching configurations changing
1083 the same attribute, the last one is used.
1084
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 load_ramdisk= [RAM] List of ramdisks to load from floppy
1086 See Documentation/ramdisk.txt.
1087
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001088 lockd.nlm_grace_period=P [NFS] Assign grace period.
1089 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001091 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1092 Format: <integer>
1093
1094 lockd.nlm_timeout=T [NFS] Assign timeout value.
1095 Format: <integer>
1096
1097 lockd.nlm_udpport=M [NFS] Assign UDP port.
1098 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099
1100 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1101 Format: <irq>
1102
1103 loglevel= All Kernel Messages with a loglevel smaller than the
1104 console loglevel will be printed to the console. It can
1105 also be changed with klogd or other programs. The
1106 loglevels are defined as follows:
1107
1108 0 (KERN_EMERG) system is unusable
1109 1 (KERN_ALERT) action must be taken immediately
1110 2 (KERN_CRIT) critical conditions
1111 3 (KERN_ERR) error conditions
1112 4 (KERN_WARNING) warning conditions
1113 5 (KERN_NOTICE) normal but significant condition
1114 6 (KERN_INFO) informational
1115 7 (KERN_DEBUG) debug-level messages
1116
1117 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001118 Format: { n | nk | nM }
1119 n must be a power of two. The default size
1120 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121
Randy Dunlapaccaa242007-10-16 01:29:37 -07001122 logo.nologo [FB] Disables display of the built-in Linux logo.
1123 This may be used to provide more screen space for
1124 kernel log messages and is useful when debugging
1125 kernel boot problems.
1126
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 lp=0 [LP] Specify parallel ports to use, e.g,
1128 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1129 lp=reset first parallel port). 'lp=0' disables the
1130 lp=auto printer driver. 'lp=reset' (which can be
1131 specified in addition to the ports) causes
1132 attached printers to be reset. Using
1133 lp=port1,port2,... specifies the parallel ports
1134 to associate lp devices with, starting with
1135 lp0. A port specification may be 'none' to skip
1136 that lp device, or a parport name such as
1137 'parport0'. Specifying 'lp=auto' instead of a
1138 port specification list means that device IDs
1139 from each port should be examined, to see if
1140 an IEEE 1284-compliant printer is attached; if
1141 so, the driver will manage that printer.
1142 See also header of drivers/char/lp.c.
1143
1144 lpj=n [KNL]
1145 Sets loops_per_jiffy to given constant, thus avoiding
1146 time-consuming boot-time autodetection (up to 250 ms per
1147 CPU). 0 enables autodetection (default). To determine
1148 the correct value for your kernel, boot with normal
1149 autodetection and see what value is printed. Note that
1150 on SMP systems the preset will be applied to all CPUs,
1151 which is likely to cause problems if your CPUs need
1152 significantly divergent settings. An incorrect value
1153 will cause delays in the kernel to be wrong, leading to
1154 unpredictable I/O errors and other breakage. Although
1155 unlikely, in the extreme case this might damage your
1156 hardware.
1157
1158 ltpc= [NET]
1159 Format: <io>,<irq>,<dma>
1160
Randy Dunlapa9913042005-10-23 12:57:11 -07001161 mac5380= [HW,SCSI] Format:
1162 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163
Randy Dunlapa9913042005-10-23 12:57:11 -07001164 machvec= [IA64] Force the use of a particular machine-vector
1165 (machvec) in a generic kernel.
1166 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167
Randy Dunlapa9913042005-10-23 12:57:11 -07001168 max_loop= [LOOP] Maximum number of loopback devices that can
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169 be mounted
1170 Format: <1-256>
1171
1172 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001173 should make use of. maxcpus=n : n >= 0 limits the
1174 kernel to using 'n' processors. n=0 is a special case,
1175 it is equivalent to "nosmp", which also disables
1176 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177
Bob Picco2b2c3752005-06-29 18:00:00 -07001178 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1179 equal to this physical address is ignored.
1180
Randy Dunlapa9913042005-10-23 12:57:11 -07001181 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182 Should be between 1 and 2^32-1.
1183
1184 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001185 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 Should be between 1 and 16384.
1187
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188 mcatest= [IA-64]
1189
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001190 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191
Andi Kleen909dd322007-10-17 18:04:38 +02001192 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1193
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194 md= [HW] RAID subsystems devices and level
1195 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001196
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 mdacon= [MDA]
1198 Format: <first>,<last>
1199 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001200
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1202 Amount of memory to be used when the kernel is not able
1203 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001204 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 address space collisions. Without memmap= PCI devices
1206 could be placed at addresses belonging to unused RAM.
1207
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001208 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 memory.
1210
Paul Mundt6902aa82008-09-21 17:14:42 +09001211 memchunk=nn[KMG]
1212 [KNL,SH] Allow user to override the default size for
1213 per-device physically contiguous DMA buffers.
1214
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001215 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 E820 memory map, as specified by the user.
1217 Such memmap=exactmap lines can be constructed based on
1218 BIOS output or other requirements. See the memmap=nn@ss
1219 option description.
1220
1221 memmap=nn[KMG]@ss[KMG]
1222 [KNL] Force usage of a specific region of memory
1223 Region of memory to be used, from ss to ss+nn.
1224
1225 memmap=nn[KMG]#ss[KMG]
1226 [KNL,ACPI] Mark specific memory as ACPI data.
1227 Region of memory to be used, from ss to ss+nn.
1228
1229 memmap=nn[KMG]$ss[KMG]
1230 [KNL,ACPI] Mark specific memory as reserved.
1231 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001232 Example: Exclude memory from 0x18690000-0x1869ffff
1233 memmap=64K$0x18690000
1234 or
1235 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001237 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001238 Format: <integer>
1239 range: 0,4 : pattern number
1240 default : 0 <disable>
1241
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 meye.*= [HW] Set MotionEye Camera parameters
1243 See Documentation/video4linux/meye.txt.
1244
Andres Salomon8f368812007-10-12 23:04:06 +02001245 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1246 Multi-Function General Purpose Timers on AMD Geode
1247 platforms.
1248
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001249 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1250 the BIOS has incorrectly applied a workaround. TinyBIOS
1251 version 0.98 is known to be affected, 0.99 fixes the
1252 problem by letting the user disable the workaround.
1253
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 mga= [HW,DRM]
1255
Mel Gorman6b74ab92008-07-23 21:26:49 -07001256 mminit_loglevel=
1257 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1258 parameter allows control of the logging verbosity for
1259 the additional memory initialisation checks. A value
1260 of 0 disables mminit logging and a level of 4 will
1261 log everything. Information is printed at KERN_DEBUG
1262 so loglevel=8 may also need to be specified.
1263
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 mousedev.tap_time=
1265 [MOUSE] Maximum time between finger touching and
1266 leaving touchpad surface for touch to be considered
1267 a tap and be reported as a left button click (for
1268 touchpads working in absolute mode only).
1269 Format: <msecs>
1270 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1271 reporting absolute coordinates, such as tablets
1272 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1273 reporting absolute coordinates, such as tablets
1274
1275 mpu401= [HW,OSS]
1276 Format: <io>,<irq>
1277
1278 MTD_Partition= [MTD]
1279 Format: <name>,<region-number>,<size>,<offset>
1280
Randy Dunlapa9913042005-10-23 12:57:11 -07001281 MTD_Region= [MTD] Format:
1282 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283
1284 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001285 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286
Ben Dooks9db829f2008-07-03 11:24:29 +01001287 mtdset= [ARM]
1288 ARM/S3C2412 JIVE boot control
1289
1290 See arch/arm/mach-s3c2412/mach-jive.c
1291
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001293 [HW] Make the MicroTouch USB driver use raw coordinates
1294 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295
1296 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1297
1298 NCR_D700= [HW,SCSI]
1299 See header of drivers/scsi/NCR_D700.c.
1300
1301 ncr5380= [HW,SCSI]
1302
1303 ncr53c400= [HW,SCSI]
1304
1305 ncr53c400a= [HW,SCSI]
1306
1307 ncr53c406a= [HW,SCSI]
1308
1309 ncr53c8xx= [HW,SCSI]
1310
1311 netdev= [NET] Network devices parameters
1312 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1313 Note that mem_start is often overloaded to mean
1314 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001315 This usage is only documented in each driver source
1316 file if at all.
1317
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001318 nf_conntrack.acct=
1319 [NETFILTER] Enable connection tracking flow accounting
1320 0 to disable accounting
1321 1 to enable accounting
1322 Default value depends on CONFIG_NF_CT_ACCT that is
1323 going to be removed in 2.6.29.
1324
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001326 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327
1328 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001329 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330
Trond Myklebusta72b4422006-01-03 09:55:41 +01001331 nfs.callback_tcpport=
1332 [NFS] set the TCP port on which the NFSv4 callback
1333 channel should listen.
1334
Trond Myklebust58df0952006-01-03 09:55:57 +01001335 nfs.idmap_cache_timeout=
1336 [NFS] set the maximum lifetime for idmapper cache
1337 entries.
1338
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001339 nfs.enable_ino64=
1340 [NFS] enable 64-bit inode numbers.
1341 If zero, the NFS client will fake up a 32-bit inode
1342 number for the readdir() and stat() syscalls instead
1343 of returning the full 64-bit number.
1344 The default is to return 64-bit inode numbers.
1345
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001346 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1347 when a NMI is triggered.
1348 Format: [state][,regs][,debounce][,die]
1349
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001350 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001352 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 emulation library even if a 387 maths coprocessor
1354 is present.
1355
Christoph Lameterc1aee212007-05-31 00:40:47 -07001356 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1357 caches in the slab allocator. Saves per-node memory,
1358 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001359
Randy Dunlapa9913042005-10-23 12:57:11 -07001360 noalign [KNL,ARM]
1361
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 noapic [SMP,APIC] Tells the kernel to not make use of any
1363 IOAPICs that may be present in the system.
1364
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 nobats [PPC] Do not use BATs for mapping kernel lowmem
1366 on "Classic" PPC cores.
1367
1368 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001369
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001370 nodelayacct [KNL] Disable per-task delay accounting
1371
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1373
Paul Mundt6902aa82008-09-21 17:14:42 +09001374 nodsp [SH] Disable hardware DSP at boot time.
1375
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001376 noefi [X86-32,X86-64] Disable EFI runtime services support.
1377
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 noexec [IA-64]
1379
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001380 noexec [X86-32,X86-64]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001381 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001383 noexec=off: disable non-executable mappings
1384
1385 noexec32 [X86-64]
1386 This affects only 32-bit executables.
1387 noexec32=on: enable non-executable mappings (default)
1388 read doesn't imply executable mappings
1389 noexec32=off: disable non-executable mappings
1390 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391
Paul Mundt6902aa82008-09-21 17:14:42 +09001392 nofpu [SH] Disable hardware FPU at boot time.
1393
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001394 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001395 register save and restore. The kernel will only save
1396 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397
Andi Kleen191679f2008-01-30 13:33:21 +01001398 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1399
Paul Mundt6902aa82008-09-21 17:14:42 +09001400 nohlt [BUGS=ARM,SH]
Randy Dunlapa9913042005-10-23 12:57:11 -07001401
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001402 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 instruction doesn't work correctly and not to
1404 use it.
1405
1406 nohalt [IA-64] Tells the kernel not to use the power saving
1407 function PAL_HALT_LIGHT when idle. This increases
1408 power-consumption. On the positive side, it reduces
1409 interrupt wake-up latency, which may improve performance
1410 in certain environments such as networked servers or
1411 real-time systems.
1412
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001413 nohz= [KNL] Boottime enable/disable dynamic ticks
1414 Valid arguments: on, off
1415 Default: on
1416
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001417 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
Zachary Amsden8542b202006-12-07 02:14:09 +01001418
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001419 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 disable unhandled interrupt sources.
1421
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001422 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001423 broken timer IRQ sources.
1424
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 noisapnp [ISAPNP] Disables ISA PnP code.
1426
1427 noinitrd [RAM] Tells the kernel not to load any configured
1428 initial RAM disk.
1429
1430 nointroute [IA-64]
1431
Tony Luck0aa366f2007-07-20 11:22:30 -07001432 nojitter [IA64] Disables jitter checking for ITC timers.
1433
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001434 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001436 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001437
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 noltlbs [PPC] Do not use large page/tlb entries for kernel
1439 lowmem mapping on PPC40x.
1440
Horms312f1f02006-02-22 09:57:55 +09001441 nomca [IA-64] Disable machine check abort handling
1442
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001443 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001444
Andres Salomon83d73842007-10-12 23:04:06 +02001445 nomfgpt [X86-32] Disable Multi-Function General Purpose
1446 Timer usage (for AMD Geode machines).
1447
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001448 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001449
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001450 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001451 with UP alternatives
1452
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453 noresidual [PPC] Don't use residual data on PReP machines.
1454
Randy Dunlapa9913042005-10-23 12:57:11 -07001455 noresume [SWSUSP] Disables resume and restores original swap
1456 space.
1457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 no-scroll [VGA] Disables scrollback.
1459 This is required for the Braillex ib80-piezo Braille
1460 reader made by F.H. Papenmeier (Germany).
1461
1462 nosbagart [IA-64]
1463
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001464 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001465
Len Brown61ec7562007-08-16 03:34:22 -04001466 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1467 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468
Dave Jones97842212007-07-15 23:41:05 -07001469 nosoftlockup [KNL] Disable the soft-lockup detector.
1470
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 nosync [HW,M68K] Disables sync negotiation for all devices.
1472
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001473 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474
1475 nousb [USB] Disable the USB subsystem
1476
1477 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001478
Fenghua Yua6c75b862008-03-14 13:57:08 -07001479 nptcg= [IA64] Override max number of concurrent global TLB
1480 purges which is reported from either PAL_VM_SUMMARY or
1481 SAL PALO.
1482
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001483 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1484 one of ['zone', 'node', 'default'] can be specified
1485 This can be set from sysctl after boot.
1486 See Documentation/sysctl/vm.txt for details.
1487
Dave Jonesa61c2d72006-01-07 23:18:19 +00001488 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1489
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001490 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1491 Rather than timing out after 20 ms if an EC
1492 command is not properly ACKed, override the length
1493 of the timeout. We have interrupts disabled while
1494 waiting for the ACK, so if this is set too high
1495 interrupts *may* be lost!
1496
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 opl3= [HW,OSS]
1498 Format: <io>
1499
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 oprofile.timer= [HW]
1501 Use timer interrupt instead of performance counters
1502
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 osst= [HW,SCSI] SCSI Tape Driver
1504 Format: <buffer_size>,<write_threshold>
1505 See also Documentation/scsi/st.txt.
1506
1507 panic= [KNL] Kernel behaviour on panic
1508 Format: <timeout>
1509
1510 parkbd.port= [HW] Parallel port number the keyboard adapter is
1511 connected to, default is 0.
1512 Format: <parport#>
1513 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1514 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001515 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516
Randy Dunlapa9913042005-10-23 12:57:11 -07001517 parport= [HW,PPT] Specify parallel ports. 0 disables.
1518 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1519 Use 'auto' to force the driver to use any
1520 IRQ/DMA settings detected (the default is to
1521 ignore detected IRQ/DMA settings because of
1522 possible conflicts). You can specify the base
1523 address, IRQ, and DMA settings; IRQ and DMA
1524 should be numbers, or 'auto' (for using detected
1525 settings on that particular port), or 'nofifo'
1526 (to avoid using a FIFO even if it is detected).
1527 Parallel ports are assigned in the order they
1528 are specified on the command line, starting
1529 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530
Randy Dunlapa9913042005-10-23 12:57:11 -07001531 parport_init_mode= [HW,PPT]
1532 Configure VIA parallel port to operate in
1533 a specific mode. This is necessary on Pegasos
1534 computer where firmware has no options for setting
1535 up parallel port mode and sets it to spp.
1536 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537 Format: [spp|ps2|epp|ecp|ecpepp]
1538
Randy Dunlapa9913042005-10-23 12:57:11 -07001539 pas2= [HW,OSS] Format:
1540 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1541
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542 pas16= [HW,SCSI]
1543 See header of drivers/scsi/pas16.c.
1544
Andrew Mortondd287792006-03-23 03:00:57 -08001545 pause_on_oops=
1546 Halt all CPUs after the first oops has been printed for
1547 the specified number of seconds. This is to be used if
1548 your oopses keep scrolling off the screen.
1549
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 pcbit= [HW,ISDN]
1551
1552 pcd. [PARIDE]
1553 See header of drivers/block/paride/pcd.c.
1554 See also Documentation/paride.txt.
1555
Randy Dunlapa9913042005-10-23 12:57:11 -07001556 pci=option[,option...] [PCI] various PCI subsystem options:
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001557 off [X86-32] don't probe for the PCI bus
1558 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001559 the hardware directly. Use this if your machine
1560 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001561 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001562 hardware access methods are allowed. Use this
1563 if you experience crashes upon bootup and you
1564 suspect they are caused by the BIOS.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001565 conf1 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001566 Mechanism 1.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001567 conf2 [X86-32] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001568 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001569 noaer [PCIE] If the PCIEAER kernel config parameter is
1570 enabled, this kernel boot option can be used to
1571 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001572 nodomains [PCI] Disable support for multiple PCI
1573 root domains (aka PCI segments, in ACPI-speak).
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001574 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001575 Configuration
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001576 nomsi [MSI] If the PCI_MSI kernel config parameter is
1577 enabled, this kernel boot option can be used to
1578 disable the use of MSI interrupts system-wide.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001579 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001580 routing table. These calls are known to be buggy
1581 on several machines and they hang the machine
1582 when used, but on other computers it's the only
1583 way to get the interrupt routing table. Try
1584 this option if the kernel is unable to allocate
1585 IRQs or discover secondary PCI buses on your
1586 motherboard.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001587 rom [X86-32] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001588 Use with caution as certain devices share
1589 address decoders between ROMs and other
1590 resources.
Gary Hadebb71ad82008-05-12 13:57:46 -07001591 norom [X86-32,X86_64] Do not assign address space to
1592 expansion ROMs that do not already have
1593 BIOS assigned address ranges.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001594 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001595 assigned automatically to PCI devices. You can
1596 make the kernel exclude IRQs of your ISA cards
1597 this way.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001598 pirqaddr=0xAAAAA [X86-32] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001599 of the PIRQ table (normally generated
1600 by the BIOS) if it is outside the
1601 F0000h-100000h range.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001602 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001603 useful if the kernel is unable to find your
1604 secondary buses and you want to tell it
1605 explicitly which ones they are.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001606 assign-busses [X86-32] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001607 numbers ourselves, overriding
1608 whatever the firmware may have done.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001609 usepirqmask [X86-32] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001610 in the BIOS $PIR table. This is needed on
1611 some systems with broken BIOSes, notably
1612 some HP Pavilion N5400 and Omnibook XE3
1613 notebooks. This will have no effect if ACPI
1614 IRQ routing is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001615 noacpi [X86-32] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001616 or for PCI scanning.
Gary Hade62f420f2007-10-03 15:56:51 -07001617 use_crs [X86-32] Use _CRS for PCI resource
1618 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001619 routeirq Do IRQ routing for all PCI devices.
1620 This is normally done in pci_enable_device(),
1621 so this option is a temporary workaround
1622 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001623 skip_isa_align [X86] do not align io start addr, so can
1624 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001625 firmware [ARM] Do not re-enumerate the bus but instead
1626 just use the configuration from the
1627 bootloader. This is currently used on
1628 IXP2000 systems where the bus has to be
1629 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001630 noearly [X86] Don't do any early type 1 scanning.
1631 This might help on some broken boards which
1632 machine check when some devices' config space
1633 is read. But various workarounds are disabled
1634 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001635 bfsort Sort PCI devices into breadth-first order.
1636 This sorting is done to get a device
1637 order compatible with older (<= 2.4) kernels.
1638 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001639 cbiosize=nn[KMG] The fixed amount of bus space which is
1640 reserved for the CardBus bridge's IO window.
1641 The default value is 256 bytes.
1642 cbmemsize=nn[KMG] The fixed amount of bus space which is
1643 reserved for the CardBus bridge's memory
1644 window. The default value is 64 megabytes.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001645
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 pcmv= [HW,PCMCIA] BadgePAD 4
1647
1648 pd. [PARIDE]
1649 See Documentation/paride.txt.
1650
1651 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1652 boot time.
1653 Format: { 0 | 1 }
1654 See arch/parisc/kernel/pdc_chassis.c
1655
1656 pf. [PARIDE]
1657 See Documentation/paride.txt.
1658
1659 pg. [PARIDE]
1660 See Documentation/paride.txt.
1661
1662 pirq= [SMP,APIC] Manual mp-table setup
1663 See Documentation/i386/IO-APIC.txt.
1664
1665 plip= [PPT,NET] Parallel port network link
1666 Format: { parport<nr> | timid | 0 }
1667 See also Documentation/parport.txt.
1668
Thomas Gleixnerde32a2432008-07-12 05:33:30 +02001669 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1670 Override pmtimer IOPort with a hex value.
1671 e.g. pmtmr=0x508
1672
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 pnpacpi= [ACPI]
1674 { off }
1675
1676 pnpbios= [ISAPNP]
1677 { on | off | curr | res | no-curr | no-res }
1678
1679 pnp_reserve_irq=
1680 [ISAPNP] Exclude IRQs for the autoconfiguration
1681
1682 pnp_reserve_dma=
1683 [ISAPNP] Exclude DMAs for the autoconfiguration
1684
1685 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07001686 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687
1688 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07001689 [ISAPNP] Exclude memory regions for the
1690 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001691 Ranges are in pairs (memory base and size).
1692
Ingo Molnar45807a12007-07-15 23:40:10 -07001693 print-fatal-signals=
1694 [KNL] debug: print fatal signals
1695 print-fatal-signals=1: print segfault info to
1696 the kernel console.
1697 default: off.
1698
Randy Dunlape84845c2007-07-15 23:40:25 -07001699 printk.time= Show timing data prefixed to each printk message line
1700 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1701
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07001703 Format: [schedule,]<number>
1704 Param: "schedule" - profile schedule points.
1705 Param: <number> - step/bucket size as a power of 2 for
1706 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02001707 Param: "sleep" - profile D-state sleeping (millisecs).
1708 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02001709 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710
Randy Dunlapa9913042005-10-23 12:57:11 -07001711 processor.max_cstate= [HW,ACPI]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 Limit processor to maximum C-state
1713 max_cstate=9 overrides any DMI blacklist limit.
1714
Len Brown41c0d862005-12-28 12:43:51 -05001715 processor.nocst [HW,ACPI]
1716 Ignore the _CST method to determine C-states,
1717 instead using the legacy FADT method
1718
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1720 before loading.
1721 See Documentation/ramdisk.txt.
1722
Randy Dunlapa9913042005-10-23 12:57:11 -07001723 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1724 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1726 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07001727 psmouse.resetafter= [HW,MOUSE]
1728 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729 (0 = never).
1730 psmouse.resolution=
1731 [HW,MOUSE] Set desired mouse resolution, in dpi.
1732 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07001733 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734 0 = disabled, 1 = enabled (default).
1735
1736 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07001737 Format:
1738 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739
1740 pt. [PARIDE]
1741 See Documentation/paride.txt.
1742
Kay Sieversdc8c8582007-08-15 12:25:38 +02001743 pty.legacy_count=
1744 [KNL] Number of legacy pty's. Overwrites compiled-in
1745 default number.
1746
Randy Dunlap7d2c5022006-09-29 02:01:02 -07001747 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07001748
Linus Torvalds1da177e2005-04-16 15:20:36 -07001749 r128= [HW,DRM]
1750
1751 raid= [HW,RAID]
1752 See Documentation/md.txt.
1753
Randy Dunlapa9913042005-10-23 12:57:11 -07001754 ramdisk_blocksize= [RAM]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 See Documentation/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001756
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 See Documentation/ramdisk.txt.
1759
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001760 rcupdate.blimit= [KNL,BOOT]
1761 Set maximum number of finished RCU callbacks to process
1762 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001763
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001764 rcupdate.qhimark= [KNL,BOOT]
1765 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001766 RCU callbacks over which batch limiting is disabled.
1767
Robert P. J. Day24aaef82008-02-03 15:20:26 +02001768 rcupdate.qlowmark= [KNL,BOOT]
1769 Set threshold of queued RCU callbacks below which
1770 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08001771
Olof Johanssonffdfc402005-09-06 15:17:19 -07001772 rdinit= [KNL]
1773 Format: <full_path>
1774 Run specified binary instead of /init from the ramdisk,
1775 used for early userspace startup. See initrd.
1776
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001777 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001779 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780
Paul Jackson46b6d942008-07-04 10:00:09 -07001781 relax_domain_level=
1782 [KNL, SMP] Set scheduler's default relax_domain_level.
1783 See Documentation/cpusets.txt.
1784
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1786
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001787 reservetop= [X86-32]
Zachary Amsden461a9aff2006-09-25 23:32:25 -07001788 Format: nn[KMG]
1789 Reserves a hole at the top of the kernel virtual
1790 address space.
1791
Vivek Goyal7e962872006-09-27 01:50:44 -07001792 reset_devices [KNL] Force drivers to reset the underlying device
1793 during initialization.
1794
Randy Dunlapa9913042005-10-23 12:57:11 -07001795 resume= [SWSUSP]
1796 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07001797
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08001798 resume_offset= [SWSUSP]
1799 Specify the offset from the beginning of the partition
1800 given by "resume=" at which the swap header is located,
1801 in <PAGE_SIZE> units (needed only for swap files).
1802 See Documentation/power/swsusp-and-swap-files.txt
1803
Michael Neuling0a7b35cb2007-02-10 01:44:33 -08001804 retain_initrd [RAM] Keep initrd memory after extraction
1805
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806 rhash_entries= [KNL,NET]
1807 Set number of hash buckets for route cache
1808
1809 riscom8= [HW,SERIAL]
1810 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1811
1812 ro [KNL] Mount root device read-only on boot
1813
1814 root= [KNL] Root filesystem
1815
1816 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1817 mount the root filesystem
1818
1819 rootflags= [KNL] Set root filesystem mount option string
1820
1821 rootfstype= [KNL] Set root filesystem type
1822
Pierre Ossmancc1ed752007-07-15 23:40:35 -07001823 rootwait [KNL] Wait (indefinitely) for root device to show up.
1824 Useful for devices that are detected asynchronously
1825 (e.g. USB and MMC devices).
1826
James Morris20510f22007-10-16 23:31:32 -07001827 root_plug.vendor_id=
1828 [ROOTPLUG] Override the default vendor ID
1829
1830 root_plug.product_id=
1831 [ROOTPLUG] Override the default product ID
1832
1833 root_plug.debug=
1834 [ROOTPLUG] Enable debugging output
1835
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836 rw [KNL] Mount root device read-write on boot
1837
1838 S [KNL] Run init in single mode
1839
1840 sa1100ir [NET]
1841 See drivers/net/irda/sa1100_ir.c.
1842
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07001844
Linus Torvalds1da177e2005-04-16 15:20:36 -07001845 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1846 Format: <io>[,<timeout>[,<isapnp>]]
1847
1848 scsi_debug_*= [SCSI]
1849 See drivers/scsi/scsi_debug.c.
1850
1851 scsi_default_dev_flags=
1852 [SCSI] SCSI default device flags
1853 Format: <integer>
1854
1855 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1856 Format: <vendor>:<model>:<flags>
1857 (flags are integer value)
1858
Randy Dunlap6af66322007-11-14 16:52:25 -08001859 scsi_logging_level= [SCSI] a bit mask of logging levels
1860 See drivers/scsi/scsi_logging.h for bits. Also
1861 settable via sysctl at dev.scsi.logging_level
1862 (/proc/sys/dev/scsi/logging_level).
1863 There is also a nice 'scsi_logging_level' script in the
1864 S390-tools package, available for download at
1865 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866
Matthew Wilcox3e082a92006-09-28 15:19:20 -06001867 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1868 discovered. async scans them in kernel threads,
1869 allowing boot to proceed. none ignores them, expecting
1870 user space to do the scan.
1871
Linus Torvalds1da177e2005-04-16 15:20:36 -07001872 selinux [SELINUX] Disable or enable SELinux at boot time.
1873 Format: { "0" | "1" }
1874 See security/selinux/Kconfig help text.
1875 0 -- disable.
1876 1 -- enable.
1877 Default value is set via kernel config option.
1878 If enabled at boot time, /selinux/disable can be used
1879 later to disable prior to initial policy load.
1880
James Morris4e5ab4c2006-06-09 00:33:33 -07001881 selinux_compat_net =
1882 [SELINUX] Set initial selinux_compat_net flag value.
Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001883 Format: { "0" | "1" }
1884 0 -- use new secmark-based packet controls
1885 1 -- use legacy packet controls
1886 Default value is 0 (preferred).
1887 Value can be changed at runtime via
1888 /selinux/compat_net.
James Morris4e5ab4c2006-06-09 00:33:33 -07001889
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001890 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 shapers= [NET]
1893 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07001894
Linus Torvalds1da177e2005-04-16 15:20:36 -07001895 sim710= [SCSI,HW]
1896 See header of drivers/scsi/sim710.c.
1897
1898 simeth= [IA-64]
1899 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07001900
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 slram= [HW,MTD]
1902
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001903 slub_debug[=options[,slabs]] [MM, SLUB]
1904 Enabling slub_debug allows one to determine the
1905 culprit if slab objects become corrupted. Enabling
1906 slub_debug can create guard zones around objects and
1907 may poison objects when not in use. Also tracks the
1908 last alloc / free. For more information see
1909 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001910
1911 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001912 Determines the maximum allowed order for slabs.
1913 A high setting may cause OOMs due to memory
1914 fragmentation. For more information see
1915 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001916
1917 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001918 The minimum number of objects per slab. SLUB will
1919 increase the slab order up to slub_max_order to
1920 generate a sufficiently large slab able to contain
1921 the number of objects indicated. The higher the number
1922 of objects the smaller the overhead of tracking slabs
1923 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001924 For more information see Documentation/vm/slub.txt.
1925
1926 slub_min_order= [MM, SLUB]
1927 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001928 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001929 For more information see Documentation/vm/slub.txt.
1930
1931 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001932 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07001933 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07001934 allocs to different slabs. Debug options disable
1935 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07001936 For more information see Documentation/vm/slub.txt.
1937
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 smart2= [HW]
1939 Format: <io1>[,<io2>[,...,<io8>]]
1940
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001941 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001942 attempt to substitute SMP alternatives once at boot.
1943
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07001944 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1945 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1946 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1947 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1948 smsc-ircc2.ircc_irq= [HW] IRQ line
1949 smsc-ircc2.ircc_dma= [HW] DMA channel
1950 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1951 0: Toshiba Satellite 1800 (GP data pin select)
1952 1: Fast pin select (default)
1953 2: ATC IRMode
1954
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 snd-ad1816a= [HW,ALSA]
1956
1957 snd-ad1848= [HW,ALSA]
1958
1959 snd-ali5451= [HW,ALSA]
1960
1961 snd-als100= [HW,ALSA]
1962
1963 snd-als4000= [HW,ALSA]
1964
1965 snd-azt2320= [HW,ALSA]
1966
1967 snd-cmi8330= [HW,ALSA]
1968
1969 snd-cmipci= [HW,ALSA]
1970
1971 snd-cs4231= [HW,ALSA]
1972
1973 snd-cs4232= [HW,ALSA]
1974
1975 snd-cs4236= [HW,ALSA]
1976
1977 snd-cs4281= [HW,ALSA]
1978
1979 snd-cs46xx= [HW,ALSA]
1980
1981 snd-dt019x= [HW,ALSA]
1982
1983 snd-dummy= [HW,ALSA]
1984
1985 snd-emu10k1= [HW,ALSA]
1986
1987 snd-ens1370= [HW,ALSA]
1988
1989 snd-ens1371= [HW,ALSA]
1990
1991 snd-es968= [HW,ALSA]
1992
1993 snd-es1688= [HW,ALSA]
1994
1995 snd-es18xx= [HW,ALSA]
1996
1997 snd-es1938= [HW,ALSA]
1998
1999 snd-es1968= [HW,ALSA]
2000
2001 snd-fm801= [HW,ALSA]
2002
2003 snd-gusclassic= [HW,ALSA]
2004
2005 snd-gusextreme= [HW,ALSA]
2006
2007 snd-gusmax= [HW,ALSA]
2008
2009 snd-hdsp= [HW,ALSA]
2010
2011 snd-ice1712= [HW,ALSA]
2012
2013 snd-intel8x0= [HW,ALSA]
2014
2015 snd-interwave= [HW,ALSA]
2016
2017 snd-interwave-stb=
2018 [HW,ALSA]
2019
2020 snd-korg1212= [HW,ALSA]
2021
2022 snd-maestro3= [HW,ALSA]
2023
2024 snd-mpu401= [HW,ALSA]
2025
2026 snd-mtpav= [HW,ALSA]
2027
2028 snd-nm256= [HW,ALSA]
2029
2030 snd-opl3sa2= [HW,ALSA]
2031
2032 snd-opti92x-ad1848=
2033 [HW,ALSA]
2034
2035 snd-opti92x-cs4231=
2036 [HW,ALSA]
2037
2038 snd-opti93x= [HW,ALSA]
2039
2040 snd-pmac= [HW,ALSA]
2041
2042 snd-rme32= [HW,ALSA]
2043
2044 snd-rme96= [HW,ALSA]
2045
2046 snd-rme9652= [HW,ALSA]
2047
2048 snd-sb8= [HW,ALSA]
2049
2050 snd-sb16= [HW,ALSA]
2051
2052 snd-sbawe= [HW,ALSA]
2053
2054 snd-serial= [HW,ALSA]
2055
2056 snd-sgalaxy= [HW,ALSA]
2057
2058 snd-sonicvibes= [HW,ALSA]
2059
2060 snd-sun-amd7930=
2061 [HW,ALSA]
2062
2063 snd-sun-cs4231= [HW,ALSA]
2064
2065 snd-trident= [HW,ALSA]
2066
2067 snd-usb-audio= [HW,ALSA,USB]
2068
2069 snd-via82xx= [HW,ALSA]
2070
2071 snd-virmidi= [HW,ALSA]
2072
2073 snd-wavefront= [HW,ALSA]
2074
2075 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002076
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002077 softlockup_panic=
2078 [KNL] Should the soft-lockup detector generate panics.
2079
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2081 See Documentation/sonypi.txt
2082
2083 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2084 See Documentation/specialix.txt.
2085
2086 spia_io_base= [HW,MTD]
2087 spia_fio_base=
2088 spia_pedr=
2089 spia_peddr=
2090
2091 sscape= [HW,OSS]
2092 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002093
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2095 See Documentation/scsi/st.txt.
2096
Linus Torvalds1da177e2005-04-16 15:20:36 -07002097 sti= [PARISC,HW]
2098 Format: <num>
2099 Set the STI (builtin display/keyboard on the HP-PARISC
2100 machines) console (graphic card) which should be used
2101 as the initial boot-console.
2102 See also comment in drivers/video/console/sticore.c.
2103
2104 sti_font= [HW]
2105 See comment in drivers/video/console/sticore.c.
2106
2107 stifb= [HW]
2108 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2109
Greg Banks42a7fc42007-03-06 01:42:23 -08002110 sunrpc.pool_mode=
2111 [NFS]
2112 Control how the NFS server code allocates CPUs to
2113 service thread pools. Depending on how many NICs
2114 you have and where their interrupts are bound, this
2115 option will affect which CPUs will do NFS serving.
2116 Note: this parameter cannot be changed while the
2117 NFS server is running.
2118
2119 auto the server chooses an appropriate mode
2120 automatically using heuristics
2121 global a single global pool contains all CPUs
2122 percpu one pool for each CPU
2123 pernode one pool for each NUMA node (equivalent
2124 to global on non-NUMA machines)
2125
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002127
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128 switches= [HW,M68k]
2129
2130 sym53c416= [HW,SCSI]
2131 See header of drivers/scsi/sym53c416.c.
2132
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002133 sysrq_always_enabled
2134 [KNL]
2135 Ignore sysrq setting - this boot parameter will
2136 neutralize any effect of /proc/sys/kernel/sysrq.
2137 Useful for debugging.
2138
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 t128= [HW,SCSI]
2140 See header of drivers/scsi/t128.c.
2141
2142 tdfx= [HW,DRM]
2143
David Brownell77437fd2008-07-23 21:28:33 -07002144 test_suspend= [SUSPEND]
2145 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2146 standby suspend) as the system sleep state to briefly
2147 enter during system startup. The system is woken from
2148 this state using a wakeup-capable RTC alarm.
2149
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150 thash_entries= [KNL,NET]
2151 Set number of hash buckets for TCP connection
2152
Len Brownf8707ec2007-08-12 00:12:54 -04002153 thermal.act= [HW,ACPI]
2154 -1: disable all active trip points in all thermal zones
2155 <degrees C>: override all lowest active trip points
2156
Len Brownc52a7412007-08-14 15:49:32 -04002157 thermal.crt= [HW,ACPI]
2158 -1: disable all critical trip points in all thermal zones
2159 <degrees C>: lower all critical trip points
2160
Len Brownf5487142007-08-12 00:12:44 -04002161 thermal.nocrt= [HW,ACPI]
2162 Set to disable actions on ACPI thermal zone
2163 critical and hot trip points.
2164
Len Brown72b33ef2007-08-12 00:12:17 -04002165 thermal.off= [HW,ACPI]
2166 1: disable ACPI thermal control
2167
Len Browna70cdc52007-08-12 00:12:35 -04002168 thermal.psv= [HW,ACPI]
2169 -1: disable all passive trip points
2170 <degrees C>: override all passive trip points to this value
2171
Len Brown730ff342007-08-12 00:12:26 -04002172 thermal.tzp= [HW,ACPI]
2173 Specify global default ACPI thermal zone polling rate
2174 <deci-seconds>: poll all this frequency
2175 0: no polling (default)
2176
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177 tmscsim= [HW,SCSI]
2178 See comment before function dc390_setup() in
2179 drivers/scsi/tmscsim.c.
2180
2181 tp720= [HW,PS2]
2182
2183 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002184 Format:
2185 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2186
Randy Dunlapa9913042005-10-23 12:57:11 -07002187 turbografx.map[2|3]= [HW,JOY]
2188 TurboGraFX parallel port interface
2189 Format:
2190 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191 See also Documentation/input/joystick-parport.txt
2192
2193 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2194 See header of drivers/scsi/u14-34f.c.
2195
2196 uart401= [HW,OSS]
2197 Format: <io>,<irq>
2198
2199 uart6850= [HW,OSS]
2200 Format: <io>,<irq>
2201
Alan Stern5f8364b2006-12-05 16:29:55 -05002202 uhci-hcd.ignore_oc=
2203 [USB] Ignore overcurrent events (default N).
2204 Some badly-designed motherboards generate lots of
2205 bogus events, for ports that aren't wired to
2206 anything. Set this parameter to avoid log spamming.
2207 Note that genuine overcurrent events won't be
2208 reported either.
2209
Simon Arlotte3a61b02008-07-19 23:32:54 +01002210 unknown_nmi_panic
2211 [X86-32,X86-64]
2212 Set unknown_nmi_panic=1 early on boot.
2213
Alan Sternb5e795f2007-02-20 15:00:53 -05002214 usbcore.autosuspend=
2215 [USB] The autosuspend time delay (in seconds) used
2216 for newly-detected USB devices (default 2). This
2217 is the time required before an idle device will be
2218 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002219 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002220
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 usbhid.mousepoll=
2222 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002223
Paul Jackson200001e2008-06-25 05:44:46 -07002224 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2225 kernel's map of available physical RAM.
2226
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002227 vdso= [X86-32,SH,x86-64]
Jeremy Fitzhardinge1dbf527c2007-05-02 19:27:12 +02002228 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002229 vdso=1: enable VDSO (default)
2230 vdso=0: disable VDSO mapping
2231
Roland McGrathaf65d642008-01-30 13:30:43 +01002232 vdso32= [X86-32,X86-64]
2233 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2234 vdso32=1: enable 32-bit VDSO (default)
2235 vdso32=0: disable 32-bit VDSO mapping
2236
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002237 vector= [IA-64,SMP]
2238 vector=percpu: enable percpu vector domain
2239
Linus Torvalds1da177e2005-04-16 15:20:36 -07002240 video= [FB] Frame buffer configuration
2241 See Documentation/fb/modedb.txt.
2242
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002243 vga= [BOOT,X86-32] Select a particular video mode
Randy Dunlapa9913042005-10-23 12:57:11 -07002244 See Documentation/i386/boot.txt and
2245 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002246 Use vga=ask for menu.
2247 This is actually a boot loader parameter; the value is
2248 passed to the kernel using a special protocol.
2249
Randy Dunlapa9913042005-10-23 12:57:11 -07002250 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251 size of <nn>. This can be used to increase the
2252 minimum size (128MB on x86). It can also be used to
2253 decrease the size and leave more room for directly
2254 mapped kernel RAM.
2255
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002256 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2257 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002259 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2260 Format: <command>
2261
2262 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2263 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002264
Linus Torvalds1da177e2005-04-16 15:20:36 -07002265 waveartist= [HW,OSS]
2266 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002267
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268 wd33c93= [HW,SCSI]
2269 See header of drivers/scsi/wd33c93.c.
2270
2271 wd7000= [HW,SCSI]
2272 See header of drivers/scsi/wd7000.c.
2273
2274 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002275 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276
2277 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2278 xd_geo= See header of drivers/block/xd.c.
2279
2280 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002281 Format:
2282 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283
Andi Kleena62eaf12006-02-16 23:41:58 +01002284 norandmaps Don't use address space randomization
2285 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2286
Randy Dunlapa9913042005-10-23 12:57:11 -07002287______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288
2289TODO:
2290
2291 Add documentation for ALSA options.
2292 Add more DRM drivers.