AMD IOMMU: add parameter to disable device isolation
[linux-block.git] / Documentation / kernel-parameters.txt
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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
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3
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
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20This 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
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27The 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:
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31
32 ACPI ACPI support is enabled.
c99c108a 33 AGP AGP (Accelerated Graphics Port) is enabled.
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34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
e7ba176b 37 AVR32 AVR32 architecture is enabled.
1da177e4 38 AX25 Appropriate AX.25 support is enabled.
0ae53640 39 BLACKFIN Blackfin architecture is enabled.
a9913044 40 DRM Direct Rendering Management support is enabled.
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41 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.
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46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
11ef697b 52 LIBATA Libata driver is enabled
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53 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.
309e57df 61 MSI Message Signaled Interrupts (PCI).
c8facbb6 62 MTD MTD (Memory Technology Device) support is enabled.
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63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
734efb46 65 GENERIC_TIME The generic timeofday code is enabled.
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66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
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68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
7f785763 72 PCIE PCI Express support is enabled.
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73 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.
20510f2f 79 ROOTPLUG The example Root Plug LSM is enabled.
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80 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/.
20510f2f 84 SECURITY Different security models are enabled.
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85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
e523d93c 87 SH SuperH architecture is enabled.
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88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
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90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
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92 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.
cd4f0ef7 100 X86-32 X86-32, aka i386 architecture is enabled.
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101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
71cced6e 103 Documentation/x86/x86_64/boot-options.txt .
c0115606 104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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105
106In addition, the following text indicates that the option:
107
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
111
112Parameters denoted with BOOT are actually interpreted by the boot
113loader, and have no meaning to the kernel directly.
114Do not modify the syntax of boot loader parameters without extreme
71cced6e 115need or coordination with <Documentation/x86/i386/boot.txt>.
1da177e4 116
5558870b 117There are also arch-specific kernel-parameters not documented here.
71cced6e 118See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 119
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120Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121a trailing = on the name of any parameter states that that parameter will
122be entered as an environment variable, whereas its absence indicates that
123it will appear as a kernel argument readable via /proc/cmdline by programs
124running once the system is up.
125
9c4751fd 126The number of kernel parameters is not limited, but the length of the
127complete command line (parameters including spaces etc.) is limited to
128a fixed number of characters. This limit depends on the architecture
129and is between 256 and 4096 characters. It is defined in the file
130./include/asm/setup.h as COMMAND_LINE_SIZE.
131
132
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133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
a9913044 135 Format: { force | off | ht | strict | noirq }
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136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
a9913044 140 strict -- Be less tolerant of platforms that are not
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141 strictly ACPI specification compliant.
142
53471121 143 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 144
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145 acpi_apic_instance= [ACPI, IOAPIC]
146 Format: <int>
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
4e381a4f 149 default: 0
a1fdcc0d 150
1da177e4 151 acpi_sleep= [HW,ACPI] Sleep options
bdfe6b7c 152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
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153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
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156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
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158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
161 used by default).
a9913044 162
1da177e4 163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 164 Format: { level | edge | high | low }
1da177e4 165
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166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
168 default in APIC mode
1da177e4 169
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170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
172 default in PIC mode
1da177e4 173
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174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
175 use by PCI
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176 Format: <irq>,<irq>...
177
a9913044 178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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179 Format: <irq>,<irq>...
180
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181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182
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183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
185
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186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
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190
191 acpi_serialize [HW,ACPI] force serialization of AML methods
192
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
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196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
199 HPET
1da177e4 200
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201 acpi_backlight= [HW,ACPI]
202 acpi_backlight=vendor
203 acpi_backlight=video
204 If set to vendor, prefer vendor specific driver
205 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
206 of the ACPI video.ko driver.
207
208 acpi_display_output= [HW,ACPI]
209 acpi_display_output=vendor
210 acpi_display_output=video
211 See above.
212
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213 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
214 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 215 Format: <int>
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216 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
217 debug output. Bits in debug_layer correspond to a
218 _COMPONENT in an ACPI source file, e.g.,
219 #define _COMPONENT ACPI_PCI_COMPONENT
220 Bits in debug_level correspond to a level in
221 ACPI_DEBUG_PRINT statements, e.g.,
222 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
223 See Documentation/acpi/debug.txt for more information
224 about debug layers and levels.
225
226 Enable AML "Debug" output, i.e., stores to the Debug
227 object while interpreting AML:
228 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
229 Enable PCI/PCI interrupt routing info messages:
230 acpi.debug_layer=0x400000 acpi.debug_level=0x4
231 Enable all messages related to ACPI hardware:
232 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
233
234 Some values produce so much output that the system is
235 unusable. The "log_buf_len" parameter may be useful
236 if you need to capture more output.
f989106c 237
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238 acpi.power_nocheck= [HW,ACPI]
239 Format: 1/0 enable/disable the check of power state.
240 On some bogus BIOS the _PSC object/_STA object of
241 power resource can't return the correct device power
242 state. In such case it is unneccessary to check its
243 power state again in power transition.
244 1 : disable the power state check
245
cd4f0ef7 246 acpi_pm_good [X86-32,X86-64]
5d0cf410 247 Override the pmtimer bug detection: force the kernel
248 to assume that this machine's pmtimer latches its value
249 and always returns good values.
250
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251 agp= [AGP]
252 { off | try_unsupported }
253 off: disable AGP support
254 try_unsupported: try to drive unsupported chipsets
255 (may crash computer or cause data corruption)
256
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257 enable_timer_pin_1 [i386,x86-64]
258 Enable PIN 1 of APIC timer
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259 Can be useful to work around chipset bugs
260 (in particular on some ATI chipsets).
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261 The kernel tries to set a reasonable default.
262
263 disable_timer_pin_1 [i386,x86-64]
264 Disable PIN 1 of APIC timer
265 Can be useful to work around chipset bugs.
266
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267 ad1848= [HW,OSS]
268 Format: <io>,<irq>,<dma>,<dma2>,<type>
269
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270 advansys= [HW,SCSI]
271 See header of drivers/scsi/advansys.c.
272
273 advwdt= [HW,WDT] Advantech WDT
274 Format: <iostart>,<iostop>
275
276 aedsp16= [HW,OSS] Audio Excel DSP 16
277 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
278 See also header of sound/oss/aedsp16.c.
a9913044 279
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280 aha152x= [HW,SCSI]
281 See Documentation/scsi/aha152x.txt.
282
283 aha1542= [HW,SCSI]
284 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
285
286 aic7xxx= [HW,SCSI]
287 See Documentation/scsi/aic7xxx.txt.
288
289 aic79xx= [HW,SCSI]
290 See Documentation/scsi/aic79xx.txt.
291
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292 amd_iommu= [HW,X86-84]
293 Pass parameters to the AMD IOMMU driver in the system.
294 Possible values are:
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295 isolate - enable device isolation (each device, as far
296 as possible, will get its own protection
297 domain)
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298 share - put every device behind one IOMMU into the
299 same protection domain
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300 fullflush - enable flushing of IO/TLB entries when
301 they are unmapped. Otherwise they are
302 flushed before they will be reused, which
303 is a lot of faster
304
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305 amd_iommu_size= [HW,X86-64]
306 Define the size of the aperture for the AMD IOMMU
307 driver. Possible values are:
308 '32M', '64M' (default), '128M', '256M', '512M', '1G'
309
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310 amijoy.map= [HW,JOY] Amiga joystick support
311 Map of devices attached to JOY0DAT and JOY1DAT
312 Format: <a>,<b>
313 See also Documentation/kernel/input/joystick.txt
314
315 analog.map= [HW,JOY] Analog joystick and gamepad support
316 Specifies type or capabilities of an analog joystick
317 connected to one of 16 gameports
318 Format: <type1>,<type2>,..<type16>
319
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320 apc= [HW,SPARC]
321 Power management functions (SPARCstation-4/5 + deriv.)
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322 Format: noidle
323 Disable APC CPU standby support. SPARCstation-Fox does
324 not play well with APC CPU idle - disable it if you have
325 APC and your system crashes randomly.
326
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327 apic= [APIC,i386] Advanced Programmable Interrupt Controller
328 Change the output verbosity whilst booting
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329 Format: { quiet (default) | verbose | debug }
330 Change the amount of debugging information output
331 when initialising the APIC and IO-APIC components.
a9913044 332
1da177e4 333 apm= [APM] Advanced Power Management
71f77055 334 See header of arch/x86/kernel/apm_32.c.
1da177e4 335
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336 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
337 Format: <io>,<irq>,<nodeID>
338
339 ataflop= [HW,M68k]
340
341 atarimouse= [HW,MOUSE] Atari Mouse
342
343 atascsi= [HW,SCSI] Atari SCSI
344
345 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
346 EzKey and similar keyboards
347
348 atkbd.reset= [HW] Reset keyboard during initialization
349
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350 atkbd.set= [HW] Select keyboard code set
351 Format: <int> (2 = AT (default), 3 = PS/2)
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352
353 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
354 keyboards
355
356 atkbd.softraw= [HW] Choose between synthetic and real raw mode
357 Format: <bool> (0 = real, 1 = synthetic (default))
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358
359 atkbd.softrepeat= [HW]
360 Use software keyboard repeat
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361
362 autotest [IA64]
363
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364 baycom_epp= [HW,AX25]
365 Format: <io>,<mode>
a9913044 366
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367 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
368 Format: <io>,<mode>
369 See header of drivers/net/hamradio/baycom_par.c.
370
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371 baycom_ser_fdx= [HW,AX25]
372 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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373 Format: <io>,<irq>,<mode>[,<baud>]
374 See header of drivers/net/hamradio/baycom_ser_fdx.c.
375
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376 baycom_ser_hdx= [HW,AX25]
377 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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378 Format: <io>,<irq>,<mode>
379 See header of drivers/net/hamradio/baycom_ser_hdx.c.
380
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381 boot_delay= Milliseconds to delay each printk during boot.
382 Values larger than 10 seconds (10000) are changed to
383 no delay (0).
384 Format: integer
385
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386 bootmem_debug [KNL] Enable bootmem allocator debug messages.
387
1da177e4 388 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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389 bttv.radio= Most important insmod options are available as
390 kernel args too.
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391 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
392 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
393
394 BusLogic= [HW,SCSI]
395 See drivers/scsi/BusLogic.c, comment before function
396 BusLogic_ParseDriverOptions().
397
398 c101= [NET] Moxa C101 synchronous serial card
399
cd4f0ef7 400 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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401 Sometimes CPU hardware bugs make them report the cache
402 size incorrectly. The kernel will attempt work arounds
403 to fix known problems, but for some CPUs it is not
404 possible to determine what the correct size should be.
405 This option provides an override for these situations.
406
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407 security= [SECURITY] Choose a security module to enable at boot.
408 If this boot parameter is not specified, only the first
409 security module asking for security registration will be
410 loaded. An invalid security module name will be treated
411 as if no module has been chosen.
412
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413 capability.disable=
414 [SECURITY] Disable capabilities. This would normally
415 be used only if an alternative security model is to be
416 configured. Potentially dangerous and should only be
417 used if you are entirely sure of the consequences.
418
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419 ccw_timeout_log [S390]
420 See Documentation/s390/CommonIO for details.
1da177e4 421
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422 cgroup_disable= [KNL] Disable a particular controller
423 Format: {name of the controller(s) to disable}
424 {Currently supported controllers - "memory"}
425
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426 checkreqprot [SELINUX] Set initial checkreqprot flag value.
427 Format: { "0" | "1" }
428 See security/selinux/Kconfig help text.
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429 0 -- check protection applied by kernel (includes
430 any implied execute protection).
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431 1 -- check protection requested by application.
432 Default value is set via a kernel config option.
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433 Value can be changed at runtime via
434 /selinux/checkreqprot.
435
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436 cio_ignore= [S390]
437 See Documentation/s390/CommonIO for details.
438
cd4f0ef7 439 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 440 [Deprecated]
3f6dee9b 441 Forces specified clocksource (if available) to be used
734efb46 442 when calculating gettimeofday(). If specified
3f6dee9b 443 clocksource is not available, it defaults to PIT.
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444 Format: { pit | tsc | cyclone | pmtmr }
445
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446 clocksource= [GENERIC_TIME] Override the default clocksource
447 Format: <string>
448 Override the default clocksource and use the clocksource
449 with the name specified.
450 Some clocksource names to choose from, depending on
451 the platform:
452 [all] jiffies (this is the base, fallback clocksource)
453 [ACPI] acpi_pm
454 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
455 pxa_timer,timer3,32k_counter,timer0_1
456 [AVR32] avr32
cd4f0ef7 457 [X86-32] pit,hpet,tsc,vmi-timer;
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458 scx200_hrt on Geode; cyclone on IBM x440
459 [MIPS] MIPS
460 [PARISC] cr16
461 [S390] tod
462 [SH] SuperH
463 [SPARC64] tick
464 [X86-64] hpet,tsc
465
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466 clearcpuid=BITNUM [X86]
467 Disable CPUID feature X for the kernel. See
468 include/asm-x86/cpufeature.h for the valid bit numbers.
469 Note the Linux specific bits are not necessarily
470 stable over kernel options, but the vendor specific
471 ones should be.
472 Also note that user programs calling CPUID directly
473 or using the feature without checking anything
474 will still see it. This just prevents it from
475 being used by the kernel or shown in /proc/cpuinfo.
476 Also note the kernel might malfunction if you disable
477 some critical bits.
478
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479 code_bytes [IA32/X86_64] How many bytes of object code to print
480 in an oops report.
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481 Range: 0 - 8192
482 Default: 64
483
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484 hpet= [X86-32,HPET] option to control HPET usage
485 Format: { enable (default) | disable | force }
486 disable: disable HPET and use PIT instead
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487 force: allow force enabled of undocumented chips (ICH4,
488 VIA, nVidia)
1da177e4 489
1da177e4 490 com20020= [HW,NET] ARCnet - COM20020 chipset
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RD
491 Format:
492 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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493
494 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
495 Format: <io>[,<irq>]
496
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497 com90xx= [HW,NET]
498 ARCnet - COM90xx chipset (memory-mapped buffers)
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499 Format: <io>[,<irq>[,<memstart>]]
500
501 condev= [HW,S390] console device
502 conmode=
a9913044 503
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LT
504 console= [KNL] Output console device and options.
505
506 tty<n> Use the virtual console device <n>.
507
508 ttyS<n>[,options]
f1a1c2dc 509 ttyUSB0[,options]
1da177e4 510 Use the specified serial port. The options are of
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RD
511 the form "bbbbpnf", where "bbbb" is the baud rate,
512 "p" is parity ("n", "o", or "e"), "n" is number of
513 bits, and "f" is flow control ("r" for RTS or
514 omit it). Default is "9600n8".
515
516 See Documentation/serial-console.txt for more
517 information. See
518 Documentation/networking/netconsole.txt for an
519 alternative.
1da177e4 520
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521 uart[8250],io,<addr>[,options]
522 uart[8250],mmio,<addr>[,options]
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LT
523 Start an early, polled-mode console on the 8250/16550
524 UART at the specified I/O port or MMIO address,
525 switching to the matching ttyS device later. The
526 options are the same as for ttyS, above.
527
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528 If the device connected to the port is not a TTY but a braille
529 device, prepend "brl," before the device type, for instance
530 console=brl,ttyS0
531 For now, only VisioBraille is supported.
532
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533 earlycon= [KNL] Output early console device and options.
534 uart[8250],io,<addr>[,options]
535 uart[8250],mmio,<addr>[,options]
536 Start an early, polled-mode console on the 8250/16550
537 UART at the specified I/O port or MMIO address.
538 The options are the same as for ttyS, above.
539
8f4ce8c3
AS
540 no_console_suspend
541 [HW] Never suspend the console
542 Disable suspending of consoles during suspend and
543 hibernate operations. Once disabled, debugging
544 messages can reach various consoles while the rest
545 of the system is being put to sleep (ie, while
546 debugging driver suspend/resume hooks). This may
547 not work reliably with all consoles, but is known
548 to work with serial and VGA consoles.
549
1da177e4 550 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
551 Format:
552 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 553
dc009d92
EB
554 crashkernel=nn[KMG]@ss[KMG]
555 [KNL] Reserve a chunk of physical memory to
556 hold a kernel to switch to with kexec on panic.
557
fb391599
BW
558 crashkernel=range1:size1[,range2:size2,...][@offset]
559 [KNL] Same as above, but depends on the memory
560 in the running system. The syntax of range is
561 start-[end] where start and end are both
562 a memory unit (amount[KMG]). See also
563 Documentation/kdump/kdump.txt for a example.
564
1da177e4
LT
565 cs4232= [HW,OSS]
566 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
567
568 cs89x0_dma= [HW,NET]
569 Format: <dma>
570
571 cs89x0_media= [HW,NET]
572 Format: { rj45 | aui | bnc }
a9913044 573
a9913044 574 dasd= [HW,NET]
1da177e4
LT
575 See header of drivers/s390/block/dasd_devmap.c.
576
577 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
578 (one device per port)
579 Format: <port#>,<type>
580 See also Documentation/input/joystick-parport.txt
581
582 debug [KNL] Enable kernel debugging (events log level).
583
cae2ed9a
IM
584 debug_locks_verbose=
585 [KNL] verbose self-tests
586 Format=<0|1>
587 Print debugging info while doing the locking API
588 self-tests.
589 We default to 0 (no extra messages), setting it to
590 1 will print _a lot_ more information - normally
591 only useful to kernel developers.
592
3ac7fe5a
TG
593 debug_objects [KNL] Enable object debugging
594
d3af01f1
TG
595 debugpat [X86] Enable PAT debugging
596
2d27a966 597 decnet.addr= [HW,NET]
1da177e4
LT
598 Format: <area>[,<node>]
599 See also Documentation/networking/decnet.txt.
600
ecb77fa9 601 vt.default_blu= [VT]
55ff9780
AD
602 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
603 Change the default blue palette of the console.
604 This is a 16-member array composed of values
605 ranging from 0-255.
606
ecb77fa9 607 vt.default_grn= [VT]
55ff9780
AD
608 Format: <green0>,<green1>,<green2>,...,<green15>
609 Change the default green palette of the console.
610 This is a 16-member array composed of values
611 ranging from 0-255.
612
ecb77fa9 613 vt.default_red= [VT]
55ff9780
AD
614 Format: <red0>,<red1>,<red2>,...,<red15>
615 Change the default red palette of the console.
616 This is a 16-member array composed of values
617 ranging from 0-255.
618
ecb77fa9
ST
619 vt.default_utf8=
620 [VT]
55ff9780
AD
621 Format=<0|1>
622 Set system-wide default UTF-8 mode for all tty's.
ecb77fa9
ST
623 Default is 1, i.e. UTF-8 mode is enabled for all
624 newly opened terminals.
55ff9780 625
1da177e4
LT
626 dhash_entries= [KNL]
627 Set number of hash buckets for dentry cache.
a9913044 628
1da177e4
LT
629 digi= [HW,SERIAL]
630 IO parameters + enable/disable command.
631
632 digiepca= [HW,SERIAL]
633 See drivers/char/README.epca and
31c00fc1 634 Documentation/serial/digiepca.txt.
1da177e4 635
95ffa243
YL
636 disable_mtrr_cleanup [X86]
637 enable_mtrr_cleanup [X86]
638 The kernel tries to adjust MTRR layout from continuous
639 to discrete, to make X server driver able to add WB
640 entry later. This parameter enables/disables that.
641
642 mtrr_chunk_size=nn[KMG] [X86]
643 used for mtrr cleanup. It is largest continous chunk
644 that could hold holes aka. UC entries.
645
646 mtrr_gran_size=nn[KMG] [X86]
12031a62
YL
647 Used for mtrr cleanup. It is granularity of mtrr block.
648 Default is 1.
649 Large value could prevent small alignment from
650 using up MTRRs.
651
652 mtrr_spare_reg_nr=n [X86]
653 Format: <integer>
654 Range: 0,7 : spare reg number
655 Default : 1
656 Used for mtrr cleanup. It is spare mtrr entries number.
657 Set to 2 or more if your graphical card needs more.
95ffa243 658
093af8d7 659 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
660 By default the kernel will trim any uncacheable
661 memory out of your available memory pool based on
662 MTRR settings. This parameter disables that behavior,
663 possibly causing your machine to run very slowly.
664
1da177e4
LT
665 dmasound= [HW,OSS] Sound subsystem buffers
666
667 dscc4.setup= [NET]
668
669 dtc3181e= [HW,SCSI]
670
0ae53640 671 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
1da177e4
LT
672 earlyprintk=vga
673 earlyprintk=serial[,ttySn[,baudrate]]
5c05917e 674 earlyprintk=dbgp
1da177e4 675
a9913044 676 Append ",keep" to not disable it when the real console
1da177e4
LT
677 takes over.
678
5c05917e 679 Only vga or serial or usb debug port at a time.
1da177e4
LT
680
681 Currently only ttyS0 and ttyS1 are supported.
682
683 Interaction with the standard serial driver is not
684 very good.
685
686 The VGA output is eventually overwritten by the real
687 console.
688
689 eata= [HW,SCSI]
690
1da177e4 691 edd= [EDD]
8c4dd606 692 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 693
1da177e4
LT
694 eisa_irq_edge= [PARISC,HW]
695 See header of drivers/parisc/eisa.c.
696
cd4f0ef7 697 elanfreq= [X86-32]
1da177e4 698 See comment before function elanfreq_setup() in
71f77055 699 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
700
701 elevator= [IOSCHED]
16ab3adf 702 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
703 See Documentation/block/as-iosched.txt and
704 Documentation/block/deadline-iosched.txt for details.
705
e515a0d6 706 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
a9913044 707 Specifies physical address of start of kernel core
aac04b32
VG
708 image elf header. Generally kexec loader will
709 pass this option to capture kernel.
710 See Documentation/kdump/kdump.txt for details.
1da177e4
LT
711
712 enforcing [SELINUX] Set initial enforcing status.
713 Format: {"0" | "1"}
714 See security/selinux/Kconfig help text.
715 0 -- permissive (log only, no denials).
716 1 -- enforcing (deny and log).
717 Default value is 0.
718 Value can be changed at runtime via /selinux/enforce.
719
1da177e4
LT
720 es1371= [HW,OSS]
721 Format: <spdif>,[<nomix>,[<amplifier>]]
722 See also header of sound/oss/es1371.c.
a9913044 723
1da177e4
LT
724 ether= [HW,NET] Ethernet cards parameters
725 This option is obsoleted by the "netdev=" option, which
726 has equivalent usage. See its documentation for details.
727
728 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
729 Format: <io>[,<irq>]
730
de1ba09b
AM
731 failslab=
732 fail_page_alloc=
733 fail_make_request=[KNL]
734 General fault injection mechanism.
735 Format: <interval>,<probability>,<space>,<times>
736 See also /Documentation/fault-injection/.
737
1da177e4
LT
738 fd_mcs= [HW,SCSI]
739 See header of drivers/scsi/fd_mcs.c.
740
741 fdomain= [HW,SCSI]
742 See header of drivers/scsi/fdomain.c.
743
744 floppy= [HW]
31c00fc1 745 See Documentation/blockdev/floppy.txt.
1da177e4 746
f13ae30e
AC
747 force_pal_cache_flush
748 [IA-64] Avoid check_sal_cache_flush which may hang on
749 buggy SAL_CACHE_FLUSH implementations. Using this
750 parameter will force ia64_sal_cache_flush to call
751 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
752
1da177e4
LT
753 gamecon.map[2|3]=
754 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
755 support via parallel port (up to 5 devices per port)
756 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
757 See also Documentation/input/joystick-parport.txt
758
759 gamma= [HW,DRM]
760
aaf23042
YL
761 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
762 Format: off | on
763 default: on
764
1da177e4
LT
765 gdth= [HW,SCSI]
766 See header of drivers/scsi/gdth.c.
767
768 gpt [EFI] Forces disk with valid GPT signature but
769 invalid Protective MBR to be treated as GPT.
770
1da177e4
LT
771 gvp11= [HW,SCSI]
772
773 hashdist= [KNL,NUMA] Large hashes allocated during boot
774 are distributed across NUMA nodes. Defaults on
775 for IA-64, off otherwise.
a9913044 776 Format: 0 | 1 (for off | on)
1da177e4
LT
777
778 hcl= [IA-64] SGI's Hardware Graph compatibility layer
779
780 hd= [EIDE] (E)IDE hard drive subsystem geometry
781 Format: <cyl>,<head>,<sect>
782
1da177e4
LT
783 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
784 size of <nn>. This works even on boxes that have no
785 highmem otherwise. This also works to reduce highmem
786 size on bigger boxes.
787
54cdfdb4
TG
788 highres= [KNL] Enable/disable high resolution timer mode.
789 Valid parameters: "on", "off"
790 Default: "on"
791
1da177e4
LT
792 hisax= [HW,ISDN]
793 See Documentation/isdn/README.HiSax.
794
b4718e62
AK
795 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
796 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
797 On x86-64 and powerpc, this option can be specified
798 multiple times interleaved with hugepages= to reserve
799 huge pages of different sizes. Valid pages sizes on
800 x86-64 are 2M (when the CPU supports "pse") and 1G
801 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
802 Note that 1GB pages can only be allocated at boot time
803 using hugepages= and not freed afterwards.
e11bfbfc
NP
804 default_hugepagesz=
805 [same as hugepagesz=] The size of the default
806 HugeTLB page size. This is the size represented by
807 the legacy /proc/ hugepages APIs, used for SHM, and
808 default size when mounting hugetlbfs filesystems.
809 Defaults to the default architecture's huge page size
810 if not specified.
1da177e4 811
6902aa84
PM
812 hlt [BUGS=ARM,SH]
813
36d95739 814 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 815 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
816 i8042.dumbkbd [HW] Pretend that controller can only read data from
817 keyboard and cannot control its state
1da177e4
LT
818 (Don't attempt to blink the leds)
819 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 820 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
821 i8042.noloop [HW] Disable the AUX Loopback command while probing
822 for the AUX port
1da177e4
LT
823 i8042.nomux [HW] Don't check presence of an active multiplexing
824 controller
825 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
826 controllers
827 i8042.panicblink=
828 [HW] Frequency with which keyboard LEDs should blink
829 when kernel panics (default is 0.5 sec)
830 i8042.reset [HW] Reset the controller during init and cleanup
831 i8042.unlock [HW] Unlock (ignore) the keylock
832
833 i810= [HW,DRM]
834
e70c9d5e
DT
835 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
836 indicates that the driver is running on unsupported
837 hardware.
1da177e4
LT
838 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
839 does not match list of supported models.
840 i8k.power_status
841 [HW] Report power status in /proc/i8k
842 (disabled by default)
843 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
844 capability is set.
845
846 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
847 See Documentation/mca.txt.
848
849 icn= [HW,ISDN]
850 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
851
852 ide= [HW] (E)IDE subsystem
a594eeb1 853 Format: ide=nodma or ide=doubler
1c10e938 854 See Documentation/ide/ide.txt.
1da177e4 855
1da177e4 856 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
1c10e938 857 See Documentation/ide/ide.txt.
1da177e4 858
f039b754 859 idle= [X86]
da5e09a1 860 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
f039b754
AK
861 Poll forces a polling idle loop that can slightly improves the performance
862 of waking up a idle CPU, but will use a lot of power and make the system
863 run hot. Not recommended.
864 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
865 to not use it because it doesn't save as much power as a normal idle
866 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
867 as idle=poll.
c1e3b377
ZY
868 idle=halt. Halt is forced to be used for CPU idle.
869 In such case C2/C3 won't be used again.
da5e09a1 870 idle=nomwait. Disable mwait for CPU C-states
a9913044 871
594765a7
DC
872 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
873 Claim all unknown PCI IDE storage controllers.
874
79290822
IM
875 ignore_loglevel [KNL]
876 Ignore loglevel setting - this will print /all/
877 kernel messages to the console. Useful for debugging.
878
1da177e4
LT
879 ihash_entries= [KNL]
880 Set number of hash buckets for inode cache.
881
882 in2000= [HW,SCSI]
883 See header of drivers/scsi/in2000.c.
884
885 init= [KNL]
886 Format: <full_path>
887 Run specified binary instead of /sbin/init as init
888 process.
889
890 initcall_debug [KNL] Trace initcalls as they are executed. Useful
891 for working out where the kernel is dying during
892 startup.
893
894 initrd= [BOOT] Specify the location of the initial ramdisk
895
896 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
897 Format: <irq>
898
899 inttest= [IA64]
900
b552da87
PM
901 iommu= [x86]
902 off
903 force
904 noforce
905 biomerge
906 panic
907 nopanic
908 merge
909 nomerge
910 forcesac
911 soft
912
913
ba395927
KA
914 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
915 off
916 Disable intel iommu driver.
917 igfx_off [Default Off]
918 By default, gfx is mapped as normal device. If a gfx
919 device has a dedicated DMAR unit, the DMAR unit is
920 bypassed by not enabling DMAR with this option. In
921 this case, gfx device will use physical address for
922 DMA.
7d3b03ce
KA
923 forcedac [x86_64]
924 With this option iommu will not optimize to look
925 for io virtual address below 32 bit forcing dual
926 address cycle on pci bus for cards supporting greater
927 than 32 bit addressing. The default is to look
928 for translation below 32 bit and if not available
929 then look in the higher range.
5e0d2a6f 930 strict [Default Off]
931 With this option on every unmap_single operation will
932 result in a hardware IOTLB flush operation as opposed
933 to batching them for performance.
ba395927 934
b02aae9c 935 io_delay= [X86-32,X86-64] I/O delay method
6e7c4025
IM
936 0x80
937 Standard port 0x80 based delay
938 0xed
939 Alternate port 0xed based delay (needed on some systems)
b02aae9c 940 udelay
6e7c4025
IM
941 Simple two microseconds delay
942 none
943 No delay
b02aae9c 944
1da177e4
LT
945 io7= [HW] IO7 for Marvel based alpha systems
946 See comment before marvel_specify_io7 in
947 arch/alpha/kernel/core_marvel.c.
948
949 ip= [IP_PNP]
6ded55da 950 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
951
952 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
953 See comment before ip2_setup() in
954 drivers/char/ip2/ip2base.c.
1da177e4
LT
955
956 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
957 See header of drivers/scsi/ips.c.
958
72c4a13a
SH
959 ports= [IP_VS_FTP] IPVS ftp helper module
960 Default is 21.
961 Up to 8 (IP_VS_APP_MAX_PORTS) ports
962 may be specified.
963 Format: <port>,<port>....
964
200803df
AC
965 irqfixup [HW]
966 When an interrupt is not handled search all handlers
967 for it. Intended to get systems with badly broken
968 firmware running.
969
970 irqpoll [HW]
971 When an interrupt is not handled search all handlers
972 for it. Also check all handlers each timer
973 interrupt. Intended to get systems with badly broken
974 firmware running.
975
1da177e4 976 isapnp= [ISAPNP]
a9913044 977 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
978
979 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
980 Format:
981 <cpu number>,...,<cpu number>
982 or
b225d44e
LZ
983 <cpu number>-<cpu number>
984 (must be a positive range in ascending order)
22f2e280
DF
985 or a mixture
986 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 987
1da177e4
LT
988 This option can be used to specify one or more CPUs
989 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
990 algorithms. You can move a process onto or off an
991 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
992 <cpu number> begins at 0 and the maximum value is
993 "number of CPUs in system - 1".
994
995 This option is the preferred way to isolate CPUs. The
a9913044
RD
996 alternative -- manually setting the CPU mask of all
997 tasks in the system -- can cause problems and
998 suboptimal load balancer performance.
1da177e4 999
a9913044 1000 iucv= [HW,NET]
1da177e4
LT
1001
1002 js= [HW,JOY] Analog joystick
1003 See Documentation/input/joystick.txt.
1004
cd4f0ef7 1005 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
ed7ed365
MG
1006 specifies the amount of memory usable by the kernel
1007 for non-movable allocations. The requested amount is
1008 spread evenly throughout all nodes in the system. The
1009 remaining memory in each node is used for Movable
1010 pages. In the event, a node is too small to have both
1011 kernelcore and Movable pages, kernelcore pages will
1012 take priority and other nodes will have a larger number
1013 of kernelcore pages. The Movable zone is used for the
1014 allocation of pages that may be reclaimed or moved
1015 by the page migration subsystem. This means that
1016 HugeTLB pages may not be allocated from this zone.
1017 Note that allocations like PTEs-from-HighMem still
1018 use the HighMem zone if it exists, and the Normal
1019 zone if it does not.
1020
cd4f0ef7 1021 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
7e63efef
MG
1022 is similar to kernelcore except it specifies the
1023 amount of memory used for migratable allocations.
1024 If both kernelcore and movablecore is specified,
1025 then kernelcore will be at *least* the specified
1026 value but may be more. If movablecore on its own
1027 is specified, the administrator must be careful
1028 that the amount of memory usable for all allocations
1029 is not too small.
1030
1da177e4
LT
1031 keepinitrd [HW,ARM]
1032
cd4f0ef7 1033 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1da177e4
LT
1034 in oops dumps.
1035
6cdf6e06
JW
1036 kgdboc= [HW] kgdb over consoles.
1037 Requires a tty driver that supports console polling.
1038 (only serial suported for now)
1039 Format: <serial_device>[,baud]
1040
9bed90c6
FF
1041 kmac= [MIPS] korina ethernet MAC address.
1042 Configure the RouterBoard 532 series on-chip
1043 Ethernet adapter MAC address.
1044
1da177e4
LT
1045 l2cr= [PPC]
1046
a78bfbfc
RB
1047 l3cr= [PPC]
1048
cd4f0ef7 1049 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1050 disabled it.
1da177e4 1051
cd4f0ef7 1052 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
e585bef8
TG
1053 C2 power state.
1054
fcb71f6f
FC
1055 libata.dma= [LIBATA] DMA control
1056 libata.dma=0 Disable all PATA and SATA DMA
1057 libata.dma=1 PATA and SATA Disk DMA only
1058 libata.dma=2 ATAPI (CDROM) DMA only
1059 libata.dma=4 Compact Flash DMA only
1060 Combinations also work, so libata.dma=3 enables DMA
1061 for disks and CDROMs, but not CFs.
1062
78e70c23
DJ
1063 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1064 when set.
1065 Format: <int>
1066
33267325
TH
1067 libata.force= [LIBATA] Force configurations. The format is comma
1068 separated list of "[ID:]VAL" where ID is
1069 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1070 matching port, link or device. Basically, it matches
1071 the ATA ID string printed on console by libata. If
1072 the whole ID part is omitted, the last PORT and DEVICE
1073 values are used. If ID hasn't been specified yet, the
1074 configuration applies to all ports, links and devices.
1075
1076 If only DEVICE is omitted, the parameter applies to
1077 the port and all links and devices behind it. DEVICE
1078 number of 0 either selects the first device or the
1079 first fan-out link behind PMP device. It does not
1080 select the host link. DEVICE number of 15 selects the
1081 host link and device attached to it.
1082
1083 The VAL specifies the configuration to force. As long
1084 as there's no ambiguity shortcut notation is allowed.
1085 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1086 The following configurations can be forced.
1087
1088 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1089 Any ID with matching PORT is used.
1090
1091 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1092
1093 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1094 udma[/][16,25,33,44,66,100,133] notation is also
1095 allowed.
1096
1097 * [no]ncq: Turn on or off NCQ.
1098
05944bdf
TH
1099 * nohrst, nosrst, norst: suppress hard, soft
1100 and both resets.
1101
33267325
TH
1102 If there are multiple matching configurations changing
1103 the same attribute, the last one is used.
1104
1da177e4 1105 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1106 See Documentation/blockdev/ramdisk.txt.
1da177e4 1107
a6b25b67
RD
1108 lockd.nlm_grace_period=P [NFS] Assign grace period.
1109 Format: <integer>
1da177e4 1110
a6b25b67
RD
1111 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1112 Format: <integer>
1113
1114 lockd.nlm_timeout=T [NFS] Assign timeout value.
1115 Format: <integer>
1116
1117 lockd.nlm_udpport=M [NFS] Assign UDP port.
1118 Format: <integer>
1da177e4
LT
1119
1120 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1121 Format: <irq>
1122
1123 loglevel= All Kernel Messages with a loglevel smaller than the
1124 console loglevel will be printed to the console. It can
1125 also be changed with klogd or other programs. The
1126 loglevels are defined as follows:
1127
1128 0 (KERN_EMERG) system is unusable
1129 1 (KERN_ALERT) action must be taken immediately
1130 2 (KERN_CRIT) critical conditions
1131 3 (KERN_ERR) error conditions
1132 4 (KERN_WARNING) warning conditions
1133 5 (KERN_NOTICE) normal but significant condition
1134 6 (KERN_INFO) informational
1135 7 (KERN_DEBUG) debug-level messages
1136
1137 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1138 Format: { n | nk | nM }
1139 n must be a power of two. The default size
1140 is set in the kernel config file.
1da177e4 1141
accaa24c
RD
1142 logo.nologo [FB] Disables display of the built-in Linux logo.
1143 This may be used to provide more screen space for
1144 kernel log messages and is useful when debugging
1145 kernel boot problems.
1146
1da177e4
LT
1147 lp=0 [LP] Specify parallel ports to use, e.g,
1148 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1149 lp=reset first parallel port). 'lp=0' disables the
1150 lp=auto printer driver. 'lp=reset' (which can be
1151 specified in addition to the ports) causes
1152 attached printers to be reset. Using
1153 lp=port1,port2,... specifies the parallel ports
1154 to associate lp devices with, starting with
1155 lp0. A port specification may be 'none' to skip
1156 that lp device, or a parport name such as
1157 'parport0'. Specifying 'lp=auto' instead of a
1158 port specification list means that device IDs
1159 from each port should be examined, to see if
1160 an IEEE 1284-compliant printer is attached; if
1161 so, the driver will manage that printer.
1162 See also header of drivers/char/lp.c.
1163
1164 lpj=n [KNL]
1165 Sets loops_per_jiffy to given constant, thus avoiding
1166 time-consuming boot-time autodetection (up to 250 ms per
1167 CPU). 0 enables autodetection (default). To determine
1168 the correct value for your kernel, boot with normal
1169 autodetection and see what value is printed. Note that
1170 on SMP systems the preset will be applied to all CPUs,
1171 which is likely to cause problems if your CPUs need
1172 significantly divergent settings. An incorrect value
1173 will cause delays in the kernel to be wrong, leading to
1174 unpredictable I/O errors and other breakage. Although
1175 unlikely, in the extreme case this might damage your
1176 hardware.
1177
1178 ltpc= [NET]
1179 Format: <io>,<irq>,<dma>
1180
a9913044
RD
1181 mac5380= [HW,SCSI] Format:
1182 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1183
a9913044
RD
1184 machvec= [IA64] Force the use of a particular machine-vector
1185 (machvec) in a generic kernel.
1186 Example: machvec=hpzx1_swiotlb
1da177e4 1187
a9913044 1188 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
1189 be mounted
1190 Format: <1-256>
1191
1192 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1193 should make use of. maxcpus=n : n >= 0 limits the
1194 kernel to using 'n' processors. n=0 is a special case,
1195 it is equivalent to "nosmp", which also disables
1196 the IO APIC.
1da177e4 1197
2b2c3750
BP
1198 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1199 equal to this physical address is ignored.
1200
a9913044 1201 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1202 Should be between 1 and 2^32-1.
1203
1204 max_report_luns=
a9913044 1205 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1206 Should be between 1 and 16384.
1207
1da177e4
LT
1208 mcatest= [IA-64]
1209
cd4f0ef7 1210 mce [X86-32] Machine Check Exception
1da177e4 1211
71cced6e 1212 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1213
1da177e4
LT
1214 md= [HW] RAID subsystems devices and level
1215 See Documentation/md.txt.
a9913044 1216
1da177e4
LT
1217 mdacon= [MDA]
1218 Format: <first>,<last>
1219 Specifies range of consoles to be captured by the MDA.
a9913044 1220
1da177e4
LT
1221 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1222 Amount of memory to be used when the kernel is not able
1223 to see the whole system memory or for test.
cd4f0ef7 1224 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1225 address space collisions. Without memmap= PCI devices
1226 could be placed at addresses belonging to unused RAM.
1227
cd4f0ef7 1228 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1229 memory.
1230
6902aa84
PM
1231 memchunk=nn[KMG]
1232 [KNL,SH] Allow user to override the default size for
1233 per-device physically contiguous DMA buffers.
1234
cd4f0ef7 1235 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1da177e4
LT
1236 E820 memory map, as specified by the user.
1237 Such memmap=exactmap lines can be constructed based on
1238 BIOS output or other requirements. See the memmap=nn@ss
1239 option description.
1240
1241 memmap=nn[KMG]@ss[KMG]
1242 [KNL] Force usage of a specific region of memory
1243 Region of memory to be used, from ss to ss+nn.
1244
1245 memmap=nn[KMG]#ss[KMG]
1246 [KNL,ACPI] Mark specific memory as ACPI data.
1247 Region of memory to be used, from ss to ss+nn.
1248
1249 memmap=nn[KMG]$ss[KMG]
1250 [KNL,ACPI] Mark specific memory as reserved.
1251 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1252 Example: Exclude memory from 0x18690000-0x1869ffff
1253 memmap=64K$0x18690000
1254 or
1255 memmap=0x10000$0x18690000
1da177e4 1256
9f077871
JF
1257 memory_corruption_check=0/1 [X86]
1258 Some BIOSes seem to corrupt the first 64k of
1259 memory when doing things like suspend/resume.
1260 Setting this option will scan the memory
1261 looking for corruption. Enabling this will
1262 both detect corruption and prevent the kernel
1263 from using the memory being corrupted.
1264 However, its intended as a diagnostic tool; if
1265 repeatable BIOS-originated corruption always
1266 affects the same memory, you can use memmap=
1267 to prevent the kernel from using that memory.
1268
1269 memory_corruption_check_size=size [X86]
1270 By default it checks for corruption in the low
1271 64k, making this memory unavailable for normal
1272 use. Use this parameter to scan for
1273 corruption in more or less memory.
1274
1275 memory_corruption_check_period=seconds [X86]
1276 By default it checks for corruption every 60
1277 seconds. Use this parameter to check at some
1278 other rate. 0 disables periodic checking.
1279
caadbdce 1280 memtest= [KNL,X86] Enable memtest
c64df707
YL
1281 Format: <integer>
1282 range: 0,4 : pattern number
1283 default : 0 <disable>
1284
1da177e4
LT
1285 meye.*= [HW] Set MotionEye Camera parameters
1286 See Documentation/video4linux/meye.txt.
1287
8f36881b
AS
1288 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1289 Multi-Function General Purpose Timers on AMD Geode
1290 platforms.
1291
e6c4dc6c
WT
1292 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1293 the BIOS has incorrectly applied a workaround. TinyBIOS
1294 version 0.98 is known to be affected, 0.99 fixes the
1295 problem by letting the user disable the workaround.
1296
1da177e4
LT
1297 mga= [HW,DRM]
1298
6b74ab97
MG
1299 mminit_loglevel=
1300 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1301 parameter allows control of the logging verbosity for
1302 the additional memory initialisation checks. A value
1303 of 0 disables mminit logging and a level of 4 will
1304 log everything. Information is printed at KERN_DEBUG
1305 so loglevel=8 may also need to be specified.
1306
1da177e4
LT
1307 mousedev.tap_time=
1308 [MOUSE] Maximum time between finger touching and
1309 leaving touchpad surface for touch to be considered
1310 a tap and be reported as a left button click (for
1311 touchpads working in absolute mode only).
1312 Format: <msecs>
1313 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1314 reporting absolute coordinates, such as tablets
1315 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1316 reporting absolute coordinates, such as tablets
1317
1318 mpu401= [HW,OSS]
1319 Format: <io>,<irq>
1320
1321 MTD_Partition= [MTD]
1322 Format: <name>,<region-number>,<size>,<offset>
1323
a9913044
RD
1324 MTD_Region= [MTD] Format:
1325 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1326
1327 mtdparts= [MTD]
c8facbb6 1328 See drivers/mtd/cmdlinepart.c.
1da177e4 1329
9db829f4
BD
1330 mtdset= [ARM]
1331 ARM/S3C2412 JIVE boot control
1332
1333 See arch/arm/mach-s3c2412/mach-jive.c
1334
1da177e4 1335 mtouchusb.raw_coordinates=
a9913044
RD
1336 [HW] Make the MicroTouch USB driver use raw coordinates
1337 ('y', default) or cooked coordinates ('n')
1da177e4
LT
1338
1339 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1340
1341 NCR_D700= [HW,SCSI]
1342 See header of drivers/scsi/NCR_D700.c.
1343
1344 ncr5380= [HW,SCSI]
1345
1346 ncr53c400= [HW,SCSI]
1347
1348 ncr53c400a= [HW,SCSI]
1349
1350 ncr53c406a= [HW,SCSI]
1351
1352 ncr53c8xx= [HW,SCSI]
1353
1354 netdev= [NET] Network devices parameters
1355 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1356 Note that mem_start is often overloaded to mean
1357 something different and driver-specific.
a9913044
RD
1358 This usage is only documented in each driver source
1359 file if at all.
1360
58401572
KPO
1361 nf_conntrack.acct=
1362 [NETFILTER] Enable connection tracking flow accounting
1363 0 to disable accounting
1364 1 to enable accounting
1365 Default value depends on CONFIG_NF_CT_ACCT that is
1366 going to be removed in 2.6.29.
1367
1da177e4 1368 nfsaddrs= [NFS]
6ded55da 1369 See Documentation/filesystems/nfsroot.txt.
1da177e4
LT
1370
1371 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
6ded55da 1372 See Documentation/filesystems/nfsroot.txt.
1da177e4 1373
a72b4422
TM
1374 nfs.callback_tcpport=
1375 [NFS] set the TCP port on which the NFSv4 callback
1376 channel should listen.
1377
58df095b
TM
1378 nfs.idmap_cache_timeout=
1379 [NFS] set the maximum lifetime for idmapper cache
1380 entries.
1381
f43bf0be
TM
1382 nfs.enable_ino64=
1383 [NFS] enable 64-bit inode numbers.
1384 If zero, the NFS client will fake up a 32-bit inode
1385 number for the readdir() and stat() syscalls instead
1386 of returning the full 64-bit number.
1387 The default is to return 64-bit inode numbers.
1388
e7ba176b
HS
1389 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1390 when a NMI is triggered.
1391 Format: [state][,regs][,debounce][,die]
1392
cd4f0ef7 1393 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1da177e4 1394
cd4f0ef7 1395 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1396 emulation library even if a 387 maths coprocessor
1397 is present.
1398
c1aee215
CL
1399 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1400 caches in the slab allocator. Saves per-node memory,
1401 but will impact performance.
3395ee05 1402
a9913044
RD
1403 noalign [KNL,ARM]
1404
1da177e4
LT
1405 noapic [SMP,APIC] Tells the kernel to not make use of any
1406 IOAPICs that may be present in the system.
1407
1da177e4
LT
1408 nobats [PPC] Do not use BATs for mapping kernel lowmem
1409 on "Classic" PPC cores.
1410
1411 nocache [ARM]
a9913044 1412
163ecdff
SN
1413 nodelayacct [KNL] Disable per-task delay accounting
1414
1da177e4
LT
1415 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1416
6902aa84
PM
1417 nodsp [SH] Disable hardware DSP at boot time.
1418
8b2cb7a8
HY
1419 noefi [X86-32,X86-64] Disable EFI runtime services support.
1420
1da177e4
LT
1421 noexec [IA-64]
1422
cd4f0ef7 1423 noexec [X86-32,X86-64]
f5a1b191 1424 On X86-32 available only on PAE configured kernels.
1da177e4 1425 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1426 noexec=off: disable non-executable mappings
1427
1428 noexec32 [X86-64]
1429 This affects only 32-bit executables.
1430 noexec32=on: enable non-executable mappings (default)
1431 read doesn't imply executable mappings
1432 noexec32=off: disable non-executable mappings
1433 read implies executable mappings
1da177e4 1434
6902aa84
PM
1435 nofpu [SH] Disable hardware FPU at boot time.
1436
cd4f0ef7 1437 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1438 register save and restore. The kernel will only save
1439 legacy floating-point registers on task switch.
1da177e4 1440
191679fd
AK
1441 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1442
6902aa84 1443 nohlt [BUGS=ARM,SH]
a9913044 1444
cd4f0ef7 1445 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1446 instruction doesn't work correctly and not to
1447 use it.
1448
1449 nohalt [IA-64] Tells the kernel not to use the power saving
1450 function PAL_HALT_LIGHT when idle. This increases
1451 power-consumption. On the positive side, it reduces
1452 interrupt wake-up latency, which may improve performance
1453 in certain environments such as networked servers or
1454 real-time systems.
1455
79bf2bb3
TG
1456 nohz= [KNL] Boottime enable/disable dynamic ticks
1457 Valid arguments: on, off
1458 Default: on
1459
cd4f0ef7 1460 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1461 disable unhandled interrupt sources.
1462
cd4f0ef7 1463 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
8542b200
ZA
1464 broken timer IRQ sources.
1465
1da177e4
LT
1466 noisapnp [ISAPNP] Disables ISA PnP code.
1467
1468 noinitrd [RAM] Tells the kernel not to load any configured
1469 initial RAM disk.
1470
1471 nointroute [IA-64]
1472
0aa366f3
TL
1473 nojitter [IA64] Disables jitter checking for ITC timers.
1474
cd4f0ef7 1475 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1476
cd4f0ef7 1477 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1478
6e1cb38a
SS
1479 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1480
af9d1388
SS
1481 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1482 default x2apic cluster mode on platforms
1483 supporting x2apic.
1484
1da177e4
LT
1485 noltlbs [PPC] Do not use large page/tlb entries for kernel
1486 lowmem mapping on PPC40x.
1487
312f1f01
H
1488 nomca [IA-64] Disable machine check abort handling
1489
cd4f0ef7 1490 nomce [X86-32] Machine Check Exception
abe37e5a 1491
83d7384f
AS
1492 nomfgpt [X86-32] Disable Multi-Function General Purpose
1493 Timer usage (for AMD Geode machines).
1494
cd4f0ef7 1495 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1496
cd4f0ef7 1497 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1498 with UP alternatives
1499
1da177e4
LT
1500 noresidual [PPC] Don't use residual data on PReP machines.
1501
a9913044
RD
1502 noresume [SWSUSP] Disables resume and restores original swap
1503 space.
1504
1da177e4
LT
1505 no-scroll [VGA] Disables scrollback.
1506 This is required for the Braillex ib80-piezo Braille
1507 reader made by F.H. Papenmeier (Germany).
1508
1509 nosbagart [IA-64]
1510
cd4f0ef7 1511 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1512
61ec7567
LB
1513 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1514 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1515
97842216
DJ
1516 nosoftlockup [KNL] Disable the soft-lockup detector.
1517
1da177e4
LT
1518 nosync [HW,M68K] Disables sync negotiation for all devices.
1519
cd4f0ef7 1520 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1521
1522 nousb [USB] Disable the USB subsystem
1523
1524 nowb [ARM]
a9913044 1525
a6c75b86
FY
1526 nptcg= [IA64] Override max number of concurrent global TLB
1527 purges which is reported from either PAL_VM_SUMMARY or
1528 SAL PALO.
1529
f0c0b2b8
KH
1530 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1531 one of ['zone', 'node', 'default'] can be specified
1532 This can be set from sysctl after boot.
1533 See Documentation/sysctl/vm.txt for details.
1534
a61c2d78
DJ
1535 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1536
3ef0e1f8
AS
1537 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1538 Rather than timing out after 20 ms if an EC
1539 command is not properly ACKed, override the length
1540 of the timeout. We have interrupts disabled while
1541 waiting for the ACK, so if this is set too high
1542 interrupts *may* be lost!
1543
1da177e4
LT
1544 opl3= [HW,OSS]
1545 Format: <io>
1546
1da177e4
LT
1547 oprofile.timer= [HW]
1548 Use timer interrupt instead of performance counters
1549
1da177e4
LT
1550 osst= [HW,SCSI] SCSI Tape Driver
1551 Format: <buffer_size>,<write_threshold>
1552 See also Documentation/scsi/st.txt.
1553
1554 panic= [KNL] Kernel behaviour on panic
1555 Format: <timeout>
1556
1557 parkbd.port= [HW] Parallel port number the keyboard adapter is
1558 connected to, default is 0.
1559 Format: <parport#>
1560 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1561 0 for XT, 1 for AT (default is AT).
a9913044
RD
1562 Format: <mode>
1563
1564 parport= [HW,PPT] Specify parallel ports. 0 disables.
1565 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1566 Use 'auto' to force the driver to use any
1567 IRQ/DMA settings detected (the default is to
1568 ignore detected IRQ/DMA settings because of
1569 possible conflicts). You can specify the base
1570 address, IRQ, and DMA settings; IRQ and DMA
1571 should be numbers, or 'auto' (for using detected
1572 settings on that particular port), or 'nofifo'
1573 (to avoid using a FIFO even if it is detected).
1574 Parallel ports are assigned in the order they
1575 are specified on the command line, starting
1576 with parport0.
1577
1578 parport_init_mode= [HW,PPT]
1579 Configure VIA parallel port to operate in
1580 a specific mode. This is necessary on Pegasos
1581 computer where firmware has no options for setting
1582 up parallel port mode and sets it to spp.
1583 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1584 Format: [spp|ps2|epp|ecp|ecpepp]
1585
a9913044
RD
1586 pas2= [HW,OSS] Format:
1587 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1588
1da177e4
LT
1589 pas16= [HW,SCSI]
1590 See header of drivers/scsi/pas16.c.
1591
dd287796
AM
1592 pause_on_oops=
1593 Halt all CPUs after the first oops has been printed for
1594 the specified number of seconds. This is to be used if
1595 your oopses keep scrolling off the screen.
1596
1da177e4
LT
1597 pcbit= [HW,ISDN]
1598
1599 pcd. [PARIDE]
1600 See header of drivers/block/paride/pcd.c.
31c00fc1 1601 See also Documentation/blockdev/paride.txt.
1da177e4 1602
a9913044 1603 pci=option[,option...] [PCI] various PCI subsystem options:
c0115606 1604 off [X86] don't probe for the PCI bus
cd4f0ef7 1605 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1606 the hardware directly. Use this if your machine
1607 has a non-standard PCI host bridge.
cd4f0ef7 1608 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1609 hardware access methods are allowed. Use this
1610 if you experience crashes upon bootup and you
1611 suspect they are caused by the BIOS.
c0115606 1612 conf1 [X86] Force use of PCI Configuration
a9913044 1613 Mechanism 1.
c0115606 1614 conf2 [X86] Force use of PCI Configuration
a9913044 1615 Mechanism 2.
7f785763
RD
1616 noaer [PCIE] If the PCIEAER kernel config parameter is
1617 enabled, this kernel boot option can be used to
1618 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1619 nodomains [PCI] Disable support for multiple PCI
1620 root domains (aka PCI segments, in ACPI-speak).
cd4f0ef7 1621 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
61be6d66 1622 Configuration
309e57df
MW
1623 nomsi [MSI] If the PCI_MSI kernel config parameter is
1624 enabled, this kernel boot option can be used to
1625 disable the use of MSI interrupts system-wide.
cd4f0ef7 1626 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1627 routing table. These calls are known to be buggy
1628 on several machines and they hang the machine
1629 when used, but on other computers it's the only
1630 way to get the interrupt routing table. Try
1631 this option if the kernel is unable to allocate
1632 IRQs or discover secondary PCI buses on your
1633 motherboard.
c0115606 1634 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1635 Use with caution as certain devices share
1636 address decoders between ROMs and other
1637 resources.
c0115606 1638 norom [X86] Do not assign address space to
bb71ad88
GH
1639 expansion ROMs that do not already have
1640 BIOS assigned address ranges.
c0115606 1641 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1642 assigned automatically to PCI devices. You can
1643 make the kernel exclude IRQs of your ISA cards
1644 this way.
c0115606 1645 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1646 of the PIRQ table (normally generated
1647 by the BIOS) if it is outside the
1648 F0000h-100000h range.
c0115606 1649 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1650 useful if the kernel is unable to find your
1651 secondary buses and you want to tell it
1652 explicitly which ones they are.
c0115606 1653 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1654 numbers ourselves, overriding
1655 whatever the firmware may have done.
c0115606 1656 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1657 in the BIOS $PIR table. This is needed on
1658 some systems with broken BIOSes, notably
1659 some HP Pavilion N5400 and Omnibook XE3
1660 notebooks. This will have no effect if ACPI
1661 IRQ routing is enabled.
c0115606 1662 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1663 or for PCI scanning.
c0115606 1664 use_crs [X86] Use _CRS for PCI resource
62f420f8 1665 allocation.
a9913044
RD
1666 routeirq Do IRQ routing for all PCI devices.
1667 This is normally done in pci_enable_device(),
1668 so this option is a temporary workaround
1669 for broken drivers that don't call it.
13a6ddb0
YL
1670 skip_isa_align [X86] do not align io start addr, so can
1671 handle more pci cards
a9913044
RD
1672 firmware [ARM] Do not re-enumerate the bus but instead
1673 just use the configuration from the
1674 bootloader. This is currently used on
1675 IXP2000 systems where the bus has to be
1676 configured a certain way for adjunct CPUs.
0637a70a
AK
1677 noearly [X86] Don't do any early type 1 scanning.
1678 This might help on some broken boards which
1679 machine check when some devices' config space
1680 is read. But various workarounds are disabled
1681 and some IOMMU drivers will not work.
6b4b78fe
MD
1682 bfsort Sort PCI devices into breadth-first order.
1683 This sorting is done to get a device
1684 order compatible with older (<= 2.4) kernels.
1685 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
1686 cbiosize=nn[KMG] The fixed amount of bus space which is
1687 reserved for the CardBus bridge's IO window.
1688 The default value is 256 bytes.
1689 cbmemsize=nn[KMG] The fixed amount of bus space which is
1690 reserved for the CardBus bridge's memory
1691 window. The default value is 64 megabytes.
6b4b78fe 1692
e5665a45
CE
1693 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1694 Management.
1695 off Disable ASPM.
1696 force Enable ASPM even on devices that claim not to support it.
1697 WARNING: Forcing ASPM on may cause system lockups.
1698
1da177e4
LT
1699 pcmv= [HW,PCMCIA] BadgePAD 4
1700
1701 pd. [PARIDE]
31c00fc1 1702 See Documentation/blockdev/paride.txt.
1da177e4
LT
1703
1704 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1705 boot time.
1706 Format: { 0 | 1 }
1707 See arch/parisc/kernel/pdc_chassis.c
1708
1709 pf. [PARIDE]
31c00fc1 1710 See Documentation/blockdev/paride.txt.
1da177e4
LT
1711
1712 pg. [PARIDE]
31c00fc1 1713 See Documentation/blockdev/paride.txt.
1da177e4
LT
1714
1715 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 1716 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
1717
1718 plip= [PPT,NET] Parallel port network link
1719 Format: { parport<nr> | timid | 0 }
1720 See also Documentation/parport.txt.
1721
de32a243
TG
1722 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1723 Override pmtimer IOPort with a hex value.
1724 e.g. pmtmr=0x508
1725
97ef062b
BH
1726 pnp.debug [PNP]
1727 Enable PNP debug messages. This depends on the
1728 CONFIG_PNP_DEBUG_MESSAGES option.
1729
1da177e4
LT
1730 pnpacpi= [ACPI]
1731 { off }
1732
1733 pnpbios= [ISAPNP]
1734 { on | off | curr | res | no-curr | no-res }
1735
1736 pnp_reserve_irq=
1737 [ISAPNP] Exclude IRQs for the autoconfiguration
1738
1739 pnp_reserve_dma=
1740 [ISAPNP] Exclude DMAs for the autoconfiguration
1741
1742 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1743 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1744
1745 pnp_reserve_mem=
a9913044
RD
1746 [ISAPNP] Exclude memory regions for the
1747 autoconfiguration.
1da177e4
LT
1748 Ranges are in pairs (memory base and size).
1749
346e15be
JB
1750 dynamic_printk
1751 Enables pr_debug()/dev_dbg() calls if
1752 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1753 be switched on/off via <debugfs>/dynamic_printk/modules
1754
45807a1d
IM
1755 print-fatal-signals=
1756 [KNL] debug: print fatal signals
1757 print-fatal-signals=1: print segfault info to
1758 the kernel console.
1759 default: off.
1760
e84845c4
RD
1761 printk.time= Show timing data prefixed to each printk message line
1762 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1763
1da177e4 1764 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1765 Format: [schedule,]<number>
1766 Param: "schedule" - profile schedule points.
1767 Param: <number> - step/bucket size as a power of 2 for
1768 statistical time based profiling.
b3da2a73
MG
1769 Param: "sleep" - profile D-state sleeping (millisecs).
1770 Requires CONFIG_SCHEDSTATS
c0fe2e69 1771 Param: "kvm" - profile VM exits.
1da177e4 1772
a9913044 1773 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1774 Limit processor to maximum C-state
1775 max_cstate=9 overrides any DMI blacklist limit.
1776
41c0d868
LB
1777 processor.nocst [HW,ACPI]
1778 Ignore the _CST method to determine C-states,
1779 instead using the legacy FADT method
1780
1da177e4
LT
1781 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1782 before loading.
31c00fc1 1783 See Documentation/blockdev/ramdisk.txt.
1da177e4 1784
a9913044
RD
1785 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1786 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1787 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1788 per second.
a9913044
RD
1789 psmouse.resetafter= [HW,MOUSE]
1790 Try to reset the device after so many bad packets
1da177e4
LT
1791 (0 = never).
1792 psmouse.resolution=
1793 [HW,MOUSE] Set desired mouse resolution, in dpi.
1794 psmouse.smartscroll=
a9913044 1795 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1796 0 = disabled, 1 = enabled (default).
1797
1798 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1799 Format:
1800 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1801
1802 pt. [PARIDE]
31c00fc1 1803 See Documentation/blockdev/paride.txt.
1da177e4 1804
dc8c8587
KS
1805 pty.legacy_count=
1806 [KNL] Number of legacy pty's. Overwrites compiled-in
1807 default number.
1808
7d2c502f 1809 quiet [KNL] Disable most log messages
a9913044 1810
1da177e4
LT
1811 r128= [HW,DRM]
1812
1813 raid= [HW,RAID]
1814 See Documentation/md.txt.
1815
a9913044 1816 ramdisk_blocksize= [RAM]
31c00fc1 1817 See Documentation/blockdev/ramdisk.txt.
a9913044 1818
1da177e4 1819 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 1820 See Documentation/blockdev/ramdisk.txt.
1da177e4 1821
24aaef8d
RD
1822 rcupdate.blimit= [KNL,BOOT]
1823 Set maximum number of finished RCU callbacks to process
1824 in one batch.
21a1ea9e 1825
24aaef8d
RD
1826 rcupdate.qhimark= [KNL,BOOT]
1827 Set threshold of queued
21a1ea9e
DS
1828 RCU callbacks over which batch limiting is disabled.
1829
24aaef8d
RD
1830 rcupdate.qlowmark= [KNL,BOOT]
1831 Set threshold of queued RCU callbacks below which
1832 batch limiting is re-enabled.
21a1ea9e 1833
ffdfc409
OJ
1834 rdinit= [KNL]
1835 Format: <full_path>
1836 Run specified binary instead of /init from the ramdisk,
1837 used for early userspace startup. See initrd.
1838
cd4f0ef7 1839 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 1840 Format: <reboot_mode>[,<reboot_mode2>[,...]]
e53dd083 1841 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 1842
46b6d94e
PJ
1843 relax_domain_level=
1844 [KNL, SMP] Set scheduler's default relax_domain_level.
1845 See Documentation/cpusets.txt.
1846
1da177e4
LT
1847 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1848
cd4f0ef7 1849 reservetop= [X86-32]
461a9aff
ZA
1850 Format: nn[KMG]
1851 Reserves a hole at the top of the kernel virtual
1852 address space.
1853
7e96287d
VG
1854 reset_devices [KNL] Force drivers to reset the underlying device
1855 during initialization.
1856
a9913044
RD
1857 resume= [SWSUSP]
1858 Specify the partition device for software suspend
1da177e4 1859
ecbd0da1
RW
1860 resume_offset= [SWSUSP]
1861 Specify the offset from the beginning of the partition
1862 given by "resume=" at which the swap header is located,
1863 in <PAGE_SIZE> units (needed only for swap files).
1864 See Documentation/power/swsusp-and-swap-files.txt
1865
0a7b35cb
MN
1866 retain_initrd [RAM] Keep initrd memory after extraction
1867
1da177e4
LT
1868 rhash_entries= [KNL,NET]
1869 Set number of hash buckets for route cache
1870
1871 riscom8= [HW,SERIAL]
1872 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1873
1874 ro [KNL] Mount root device read-only on boot
1875
1876 root= [KNL] Root filesystem
1877
1878 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1879 mount the root filesystem
1880
1881 rootflags= [KNL] Set root filesystem mount option string
1882
1883 rootfstype= [KNL] Set root filesystem type
1884
cc1ed754
PO
1885 rootwait [KNL] Wait (indefinitely) for root device to show up.
1886 Useful for devices that are detected asynchronously
1887 (e.g. USB and MMC devices).
1888
20510f2f
JM
1889 root_plug.vendor_id=
1890 [ROOTPLUG] Override the default vendor ID
1891
1892 root_plug.product_id=
1893 [ROOTPLUG] Override the default product ID
1894
1895 root_plug.debug=
1896 [ROOTPLUG] Enable debugging output
1897
1da177e4
LT
1898 rw [KNL] Mount root device read-write on boot
1899
1900 S [KNL] Run init in single mode
1901
1902 sa1100ir [NET]
1903 See drivers/net/irda/sa1100_ir.c.
1904
1da177e4 1905 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1906
1da177e4
LT
1907 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1908 Format: <io>[,<timeout>[,<isapnp>]]
1909
1910 scsi_debug_*= [SCSI]
1911 See drivers/scsi/scsi_debug.c.
1912
1913 scsi_default_dev_flags=
1914 [SCSI] SCSI default device flags
1915 Format: <integer>
1916
1917 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1918 Format: <vendor>:<model>:<flags>
1919 (flags are integer value)
1920
6af6632a
RD
1921 scsi_logging_level= [SCSI] a bit mask of logging levels
1922 See drivers/scsi/scsi_logging.h for bits. Also
1923 settable via sysctl at dev.scsi.logging_level
1924 (/proc/sys/dev/scsi/logging_level).
1925 There is also a nice 'scsi_logging_level' script in the
1926 S390-tools package, available for download at
1927 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 1928
3e082a91
MW
1929 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1930 discovered. async scans them in kernel threads,
1931 allowing boot to proceed. none ignores them, expecting
1932 user space to do the scan.
1933
1da177e4
LT
1934 selinux [SELINUX] Disable or enable SELinux at boot time.
1935 Format: { "0" | "1" }
1936 See security/selinux/Kconfig help text.
1937 0 -- disable.
1938 1 -- enable.
1939 Default value is set via kernel config option.
1940 If enabled at boot time, /selinux/disable can be used
1941 later to disable prior to initial policy load.
1942
4e5ab4cb
JM
1943 selinux_compat_net =
1944 [SELINUX] Set initial selinux_compat_net flag value.
e53dd083
MCC
1945 Format: { "0" | "1" }
1946 0 -- use new secmark-based packet controls
1947 1 -- use legacy packet controls
1948 Default value is 0 (preferred).
1949 Value can be changed at runtime via
1950 /selinux/compat_net.
4e5ab4cb 1951
cd4f0ef7 1952 serialnumber [BUGS=X86-32]
1da177e4 1953
1da177e4
LT
1954 shapers= [NET]
1955 Maximal number of shapers.
a9913044 1956
b05f78f5
YL
1957 show_msr= [x86] show boot-time MSR settings
1958 Format: { <integer> }
1959 Show boot-time (BIOS-initialized) MSR settings.
1960 The parameter means the number of CPUs to show,
1961 for example 1 means boot CPU only.
1962
1da177e4
LT
1963 sim710= [SCSI,HW]
1964 See header of drivers/scsi/sim710.c.
1965
1966 simeth= [IA-64]
1967 simscsi=
a9913044 1968
1da177e4
LT
1969 slram= [HW,MTD]
1970
f0630fff
CL
1971 slub_debug[=options[,slabs]] [MM, SLUB]
1972 Enabling slub_debug allows one to determine the
1973 culprit if slab objects become corrupted. Enabling
1974 slub_debug can create guard zones around objects and
1975 may poison objects when not in use. Also tracks the
1976 last alloc / free. For more information see
1977 Documentation/vm/slub.txt.
c1aee215
CL
1978
1979 slub_max_order= [MM, SLUB]
f0630fff
CL
1980 Determines the maximum allowed order for slabs.
1981 A high setting may cause OOMs due to memory
1982 fragmentation. For more information see
1983 Documentation/vm/slub.txt.
c1aee215
CL
1984
1985 slub_min_objects= [MM, SLUB]
f0630fff
CL
1986 The minimum number of objects per slab. SLUB will
1987 increase the slab order up to slub_max_order to
1988 generate a sufficiently large slab able to contain
1989 the number of objects indicated. The higher the number
1990 of objects the smaller the overhead of tracking slabs
1991 and the less frequently locks need to be acquired.
c1aee215
CL
1992 For more information see Documentation/vm/slub.txt.
1993
1994 slub_min_order= [MM, SLUB]
1995 Determines the mininum page order for slabs. Must be
f0630fff 1996 lower than slub_max_order.
c1aee215
CL
1997 For more information see Documentation/vm/slub.txt.
1998
1999 slub_nomerge [MM, SLUB]
f0630fff 2000 Disable merging of slabs with similar size. May be
c1aee215 2001 necessary if there is some reason to distinguish
f0630fff
CL
2002 allocs to different slabs. Debug options disable
2003 merging on their own.
c1aee215
CL
2004 For more information see Documentation/vm/slub.txt.
2005
1da177e4
LT
2006 smart2= [HW]
2007 Format: <io1>[,<io2>[,...,<io8>]]
2008
cd4f0ef7 2009 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2010 attempt to substitute SMP alternatives once at boot.
2011
d0d4f69b
BH
2012 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2013 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2014 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2015 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2016 smsc-ircc2.ircc_irq= [HW] IRQ line
2017 smsc-ircc2.ircc_dma= [HW] DMA channel
2018 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2019 0: Toshiba Satellite 1800 (GP data pin select)
2020 1: Fast pin select (default)
2021 2: ATC IRMode
2022
1da177e4
LT
2023 snd-ad1816a= [HW,ALSA]
2024
2025 snd-ad1848= [HW,ALSA]
2026
2027 snd-ali5451= [HW,ALSA]
2028
2029 snd-als100= [HW,ALSA]
2030
2031 snd-als4000= [HW,ALSA]
2032
2033 snd-azt2320= [HW,ALSA]
2034
2035 snd-cmi8330= [HW,ALSA]
2036
2037 snd-cmipci= [HW,ALSA]
2038
2039 snd-cs4231= [HW,ALSA]
2040
2041 snd-cs4232= [HW,ALSA]
2042
2043 snd-cs4236= [HW,ALSA]
2044
2045 snd-cs4281= [HW,ALSA]
2046
2047 snd-cs46xx= [HW,ALSA]
2048
2049 snd-dt019x= [HW,ALSA]
2050
2051 snd-dummy= [HW,ALSA]
2052
2053 snd-emu10k1= [HW,ALSA]
2054
2055 snd-ens1370= [HW,ALSA]
2056
2057 snd-ens1371= [HW,ALSA]
2058
2059 snd-es968= [HW,ALSA]
2060
2061 snd-es1688= [HW,ALSA]
2062
2063 snd-es18xx= [HW,ALSA]
2064
2065 snd-es1938= [HW,ALSA]
2066
2067 snd-es1968= [HW,ALSA]
2068
2069 snd-fm801= [HW,ALSA]
2070
2071 snd-gusclassic= [HW,ALSA]
2072
2073 snd-gusextreme= [HW,ALSA]
2074
2075 snd-gusmax= [HW,ALSA]
2076
2077 snd-hdsp= [HW,ALSA]
2078
2079 snd-ice1712= [HW,ALSA]
2080
2081 snd-intel8x0= [HW,ALSA]
2082
2083 snd-interwave= [HW,ALSA]
2084
2085 snd-interwave-stb=
2086 [HW,ALSA]
2087
2088 snd-korg1212= [HW,ALSA]
2089
2090 snd-maestro3= [HW,ALSA]
2091
2092 snd-mpu401= [HW,ALSA]
2093
2094 snd-mtpav= [HW,ALSA]
2095
2096 snd-nm256= [HW,ALSA]
2097
2098 snd-opl3sa2= [HW,ALSA]
2099
2100 snd-opti92x-ad1848=
2101 [HW,ALSA]
2102
2103 snd-opti92x-cs4231=
2104 [HW,ALSA]
2105
2106 snd-opti93x= [HW,ALSA]
2107
2108 snd-pmac= [HW,ALSA]
2109
2110 snd-rme32= [HW,ALSA]
2111
2112 snd-rme96= [HW,ALSA]
2113
2114 snd-rme9652= [HW,ALSA]
2115
2116 snd-sb8= [HW,ALSA]
2117
2118 snd-sb16= [HW,ALSA]
2119
2120 snd-sbawe= [HW,ALSA]
2121
2122 snd-serial= [HW,ALSA]
2123
2124 snd-sgalaxy= [HW,ALSA]
2125
2126 snd-sonicvibes= [HW,ALSA]
2127
2128 snd-sun-amd7930=
2129 [HW,ALSA]
2130
2131 snd-sun-cs4231= [HW,ALSA]
2132
2133 snd-trident= [HW,ALSA]
2134
2135 snd-usb-audio= [HW,ALSA,USB]
2136
2137 snd-via82xx= [HW,ALSA]
2138
2139 snd-virmidi= [HW,ALSA]
2140
2141 snd-wavefront= [HW,ALSA]
2142
2143 snd-ymfpci= [HW,ALSA]
a9913044 2144
9c44bc03
IM
2145 softlockup_panic=
2146 [KNL] Should the soft-lockup detector generate panics.
2147
1da177e4
LT
2148 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2149 See Documentation/sonypi.txt
2150
2151 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2152 See Documentation/serial/specialix.txt.
1da177e4
LT
2153
2154 spia_io_base= [HW,MTD]
2155 spia_fio_base=
2156 spia_pedr=
2157 spia_peddr=
2158
2159 sscape= [HW,OSS]
2160 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2161
1da177e4
LT
2162 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2163 See Documentation/scsi/st.txt.
2164
1da177e4
LT
2165 sti= [PARISC,HW]
2166 Format: <num>
2167 Set the STI (builtin display/keyboard on the HP-PARISC
2168 machines) console (graphic card) which should be used
2169 as the initial boot-console.
2170 See also comment in drivers/video/console/sticore.c.
2171
2172 sti_font= [HW]
2173 See comment in drivers/video/console/sticore.c.
2174
2175 stifb= [HW]
2176 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2177
42a7fc4a
GB
2178 sunrpc.pool_mode=
2179 [NFS]
2180 Control how the NFS server code allocates CPUs to
2181 service thread pools. Depending on how many NICs
2182 you have and where their interrupts are bound, this
2183 option will affect which CPUs will do NFS serving.
2184 Note: this parameter cannot be changed while the
2185 NFS server is running.
2186
2187 auto the server chooses an appropriate mode
2188 automatically using heuristics
2189 global a single global pool contains all CPUs
2190 percpu one pool for each CPU
2191 pernode one pool for each NUMA node (equivalent
2192 to global on non-NUMA machines)
2193
1da177e4 2194 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2195
1da177e4
LT
2196 switches= [HW,M68k]
2197
2198 sym53c416= [HW,SCSI]
2199 See header of drivers/scsi/sym53c416.c.
2200
5d6f647f
IM
2201 sysrq_always_enabled
2202 [KNL]
2203 Ignore sysrq setting - this boot parameter will
2204 neutralize any effect of /proc/sys/kernel/sysrq.
2205 Useful for debugging.
2206
1da177e4
LT
2207 t128= [HW,SCSI]
2208 See header of drivers/scsi/t128.c.
2209
2210 tdfx= [HW,DRM]
2211
77437fd4
DB
2212 test_suspend= [SUSPEND]
2213 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2214 standby suspend) as the system sleep state to briefly
2215 enter during system startup. The system is woken from
2216 this state using a wakeup-capable RTC alarm.
2217
1da177e4
LT
2218 thash_entries= [KNL,NET]
2219 Set number of hash buckets for TCP connection
2220
f8707ec9
LB
2221 thermal.act= [HW,ACPI]
2222 -1: disable all active trip points in all thermal zones
2223 <degrees C>: override all lowest active trip points
2224
c52a7419
LB
2225 thermal.crt= [HW,ACPI]
2226 -1: disable all critical trip points in all thermal zones
22a94d79 2227 <degrees C>: override all critical trip points
c52a7419 2228
f5487145
LB
2229 thermal.nocrt= [HW,ACPI]
2230 Set to disable actions on ACPI thermal zone
2231 critical and hot trip points.
2232
72b33ef8
LB
2233 thermal.off= [HW,ACPI]
2234 1: disable ACPI thermal control
2235
a70cdc52
LB
2236 thermal.psv= [HW,ACPI]
2237 -1: disable all passive trip points
2238 <degrees C>: override all passive trip points to this value
2239
730ff34d
LB
2240 thermal.tzp= [HW,ACPI]
2241 Specify global default ACPI thermal zone polling rate
2242 <deci-seconds>: poll all this frequency
2243 0: no polling (default)
2244
1da177e4
LT
2245 tmscsim= [HW,SCSI]
2246 See comment before function dc390_setup() in
2247 drivers/scsi/tmscsim.c.
2248
2249 tp720= [HW,PS2]
2250
2251 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2252 Format:
2253 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2254
a9913044
RD
2255 turbografx.map[2|3]= [HW,JOY]
2256 TurboGraFX parallel port interface
2257 Format:
2258 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2259 See also Documentation/input/joystick-parport.txt
2260
2261 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2262 See header of drivers/scsi/u14-34f.c.
2263
2264 uart401= [HW,OSS]
2265 Format: <io>,<irq>
2266
2267 uart6850= [HW,OSS]
2268 Format: <io>,<irq>
2269
5f8364b7
AS
2270 uhci-hcd.ignore_oc=
2271 [USB] Ignore overcurrent events (default N).
2272 Some badly-designed motherboards generate lots of
2273 bogus events, for ports that aren't wired to
2274 anything. Set this parameter to avoid log spamming.
2275 Note that genuine overcurrent events won't be
2276 reported either.
2277
e3a61b0a
SA
2278 unknown_nmi_panic
2279 [X86-32,X86-64]
2280 Set unknown_nmi_panic=1 early on boot.
2281
b5e795f8
AS
2282 usbcore.autosuspend=
2283 [USB] The autosuspend time delay (in seconds) used
2284 for newly-detected USB devices (default 2). This
2285 is the time required before an idle device will be
2286 autosuspended. Devices for which the delay is set
eaafbc3a 2287 to a negative value won't be autosuspended at all.
b5e795f8 2288
fd7c519d
JK
2289 usbcore.usbfs_snoop=
2290 [USB] Set to log all usbfs traffic (default 0 = off).
2291
2292 usbcore.blinkenlights=
2293 [USB] Set to cycle leds on hubs (default 0 = off).
2294
2295 usbcore.old_scheme_first=
2296 [USB] Start with the old device initialization
2297 scheme (default 0 = off).
2298
2299 usbcore.use_both_schemes=
2300 [USB] Try the other device initialization scheme
2301 if the first one fails (default 1 = enabled).
2302
2303 usbcore.initial_descriptor_timeout=
2304 [USB] Specifies timeout for the initial 64-byte
2305 USB_REQ_GET_DESCRIPTOR request in milliseconds
2306 (default 5000 = 5.0 seconds).
2307
1da177e4
LT
2308 usbhid.mousepoll=
2309 [USBHID] The interval which mice are to be polled at.
a9913044 2310
200001eb
PJ
2311 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2312 kernel's map of available physical RAM.
2313
cd4f0ef7 2314 vdso= [X86-32,SH,x86-64]
1dbf527c 2315 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2316 vdso=1: enable VDSO (default)
2317 vdso=0: disable VDSO mapping
2318
af65d648
RM
2319 vdso32= [X86-32,X86-64]
2320 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2321 vdso32=1: enable 32-bit VDSO (default)
2322 vdso32=0: disable 32-bit VDSO mapping
2323
d080d397
YI
2324 vector= [IA-64,SMP]
2325 vector=percpu: enable percpu vector domain
2326
1da177e4
LT
2327 video= [FB] Frame buffer configuration
2328 See Documentation/fb/modedb.txt.
2329
cd4f0ef7 2330 vga= [BOOT,X86-32] Select a particular video mode
71cced6e 2331 See Documentation/x86/i386/boot.txt and
a9913044 2332 Documentation/svga.txt.
1da177e4
LT
2333 Use vga=ask for menu.
2334 This is actually a boot loader parameter; the value is
2335 passed to the kernel using a special protocol.
2336
a9913044 2337 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2338 size of <nn>. This can be used to increase the
2339 minimum size (128MB on x86). It can also be used to
2340 decrease the size and leave more room for directly
2341 mapped kernel RAM.
2342
585c3047
PO
2343 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2344 Format: <command>
1da177e4 2345
585c3047
PO
2346 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2347 Format: <command>
2348
2349 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2350 Format: <command>
a9913044 2351
1da177e4
LT
2352 waveartist= [HW,OSS]
2353 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2354
1da177e4
LT
2355 wd33c93= [HW,SCSI]
2356 See header of drivers/scsi/wd33c93.c.
2357
2358 wd7000= [HW,SCSI]
2359 See header of drivers/scsi/wd7000.c.
2360
2361 wdt= [WDT] Watchdog
8dfe9c21 2362 See Documentation/watchdog/wdt.txt.
1da177e4
LT
2363
2364 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2365 xd_geo= See header of drivers/block/xd.c.
2366
2367 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2368 Format:
2369 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2370
a62eaf15
AK
2371 norandmaps Don't use address space randomization
2372 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2373
a9913044 2374______________________________________________________________________
1da177e4
LT
2375
2376TODO:
2377
2378 Add documentation for ALSA options.
2379 Add more DRM drivers.