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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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20Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
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26This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
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33The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
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37
38 ACPI ACPI support is enabled.
c99c108a 39 AGP AGP (Accelerated Graphics Port) is enabled.
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40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
e7ba176b 43 AVR32 AVR32 architecture is enabled.
1da177e4 44 AX25 Appropriate AX.25 support is enabled.
0ae53640 45 BLACKFIN Blackfin architecture is enabled.
a9913044 46 DRM Direct Rendering Management support is enabled.
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47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
2521f2c2 51 GCOV GCOV profiling is enabled.
1da177e4 52 HW Appropriate hardware is enabled.
1da177e4 53 IA-64 IA-64 architecture is enabled.
6146f0d5 54 IMA Integrity measurement architecture is enabled.
1da177e4 55 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 56 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
b0f83b28 57 IPV6 IPv6 support is enabled.
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58 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
84c08fd6 61 KGDB Kernel debugger support is enabled.
fef07aae 62 KVM Kernel Virtual Machine support is enabled.
11ef697b 63 LIBATA Libata driver is enabled
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64 LP Printer support is enabled.
65 LOOP Loopback device support is enabled.
66 M68k M68k architecture is enabled.
67 These options have more detailed description inside of
68 Documentation/m68k/kernel-options.txt.
69 MCA MCA bus support is enabled.
70 MDA MDA console support is enabled.
71 MOUSE Appropriate mouse support is enabled.
309e57df 72 MSI Message Signaled Interrupts (PCI).
c8facbb6 73 MTD MTD (Memory Technology Device) support is enabled.
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74 NET Appropriate network support is enabled.
75 NUMA NUMA support is enabled.
734efb46 76 GENERIC_TIME The generic timeofday code is enabled.
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77 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
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79 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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81 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
7f785763 83 PCIE PCI Express support is enabled.
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84 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers has their options described inside of
93 Documentation/scsi/.
20510f2f 94 SECURITY Different security models are enabled.
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95 SELINUX SELinux support is enabled.
96 SERIAL Serial support is enabled.
e523d93c 97 SH SuperH architecture is enabled.
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98 SMP The kernel is an SMP kernel.
99 SPARC Sparc architecture is enabled.
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100 SWSUSP Software suspend (hibernation) is enabled.
101 SUSPEND System suspend states are enabled.
f38f1d2a 102 FTRACE Function tracing enabled.
225a9be2 103 TPM TPM drivers are enabled.
1da177e4 104 TS Appropriate touchscreen support is enabled.
d4f373e5 105 UMS USB Mass Storage support is enabled.
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106 USB USB support is enabled.
107 USBHID USB Human Interface Device support is enabled.
108 V4L Video For Linux support is enabled.
109 VGA The VGA console has been enabled.
110 VT Virtual terminal support is enabled.
111 WDT Watchdog support is enabled.
112 XT IBM PC/XT MFM hard disk support is enabled.
cd4f0ef7 113 X86-32 X86-32, aka i386 architecture is enabled.
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114 X86-64 X86-64 architecture is enabled.
115 More X86-64 boot options can be found in
71cced6e 116 Documentation/x86/x86_64/boot-options.txt .
c0115606 117 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
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118
119In addition, the following text indicates that the option:
120
121 BUGS= Relates to possible processor bugs on the said processor.
122 KNL Is a kernel start-up parameter.
123 BOOT Is a boot loader parameter.
124
125Parameters denoted with BOOT are actually interpreted by the boot
126loader, and have no meaning to the kernel directly.
127Do not modify the syntax of boot loader parameters without extreme
954a8b81 128need or coordination with <Documentation/x86/boot.txt>.
1da177e4 129
5558870b 130There are also arch-specific kernel-parameters not documented here.
71cced6e 131See for example <Documentation/x86/x86_64/boot-options.txt>.
5558870b 132
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133Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
134a trailing = on the name of any parameter states that that parameter will
135be entered as an environment variable, whereas its absence indicates that
136it will appear as a kernel argument readable via /proc/cmdline by programs
137running once the system is up.
138
9c4751fd 139The number of kernel parameters is not limited, but the length of the
140complete command line (parameters including spaces etc.) is limited to
141a fixed number of characters. This limit depends on the architecture
142and is between 256 and 4096 characters. It is defined in the file
143./include/asm/setup.h as COMMAND_LINE_SIZE.
144
145
6cececfc 146 acpi= [HW,ACPI,X86]
03d926f8 147 Advanced Configuration and Power Interface
af23f573 148 Format: { force | off | ht | strict | noirq | rsdt }
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149 force -- enable ACPI if default was off
150 off -- disable ACPI if default was on
151 noirq -- do not use ACPI for IRQ routing
152 ht -- run only enough ACPI to enable Hyper Threading
a9913044 153 strict -- Be less tolerant of platforms that are not
1da177e4 154 strictly ACPI specification compliant.
237889bf 155 rsdt -- prefer RSDT over (default) XSDT
aa2110cb 156 copy_dsdt -- copy DSDT to memory
1da177e4 157
53471121 158 See also Documentation/power/pm.txt, pci=noacpi
1da177e4 159
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160 acpi_apic_instance= [ACPI, IOAPIC]
161 Format: <int>
162 2: use 2nd APIC table, if available
163 1,0: use 1st APIC table
4e381a4f 164 default: 0
a1fdcc0d 165
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166 acpi_backlight= [HW,ACPI]
167 acpi_backlight=vendor
168 acpi_backlight=video
169 If set to vendor, prefer vendor specific driver
170 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
171 of the ACPI video.ko driver.
172
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173 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
174 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
1da177e4 175 Format: <int>
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176 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
177 debug output. Bits in debug_layer correspond to a
178 _COMPONENT in an ACPI source file, e.g.,
179 #define _COMPONENT ACPI_PCI_COMPONENT
180 Bits in debug_level correspond to a level in
181 ACPI_DEBUG_PRINT statements, e.g.,
182 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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183 The debug_level mask defaults to "info". See
184 Documentation/acpi/debug.txt for more information about
185 debug layers and levels.
a0d84a92 186
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187 Enable processor driver info messages:
188 acpi.debug_layer=0x20000000
189 Enable PCI/PCI interrupt routing info messages:
190 acpi.debug_layer=0x400000
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191 Enable AML "Debug" output, i.e., stores to the Debug
192 object while interpreting AML:
193 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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194 Enable all messages related to ACPI hardware:
195 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
196
197 Some values produce so much output that the system is
198 unusable. The "log_buf_len" parameter may be useful
199 if you need to capture more output.
f989106c 200
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201 acpi_display_output= [HW,ACPI]
202 acpi_display_output=vendor
203 acpi_display_output=video
204 See above.
205
206 acpi_irq_balance [HW,ACPI]
207 ACPI will balance active IRQs
208 default in APIC mode
209
210 acpi_irq_nobalance [HW,ACPI]
211 ACPI will not move active IRQs (default)
212 default in PIC mode
213
214 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
215 Format: <irq>,<irq>...
216
217 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
218 use by PCI
219 Format: <irq>,<irq>...
220
221 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
222
223 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
224 Format: To spoof as Windows 98: ="Microsoft Windows"
225
226 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
227 acpi_osi="string1" # add string1 -- only one string
228 acpi_osi="!string2" # remove built-in string2
229 acpi_osi= # disable all strings
230
6cececfc 231 acpi_pm_good [X86]
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232 Override the pmtimer bug detection: force the kernel
233 to assume that this machine's pmtimer latches its value
234 and always returns good values.
235
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236 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
237 Format: { level | edge | high | low }
238
239 acpi_serialize [HW,ACPI] force serialization of AML methods
240
241 acpi_skip_timer_override [HW,ACPI]
242 Recognize and ignore IRQ0/pin2 Interrupt Override.
243 For broken nForce2 BIOS resulting in XT-PIC timer.
244
245 acpi_sleep= [HW,ACPI] Sleep options
246 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
d7f0eea9 247 old_ordering, s4_nonvs, sci_force_enable }
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248 See Documentation/power/video.txt for information on
249 s3_bios and s3_mode.
250 s3_beep is for debugging; it makes the PC's speaker beep
251 as soon as the kernel's real-mode entry point is called.
252 s4_nohwsig prevents ACPI hardware signature from being
253 used during resume from hibernation.
254 old_ordering causes the ACPI 1.0 ordering of the _PTS
255 control method, with respect to putting devices into
256 low power states, to be enforced (the ACPI 2.0 ordering
257 of _PTS is used by default).
258 s4_nonvs prevents the kernel from saving/restoring the
259 ACPI NVS memory during hibernation.
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260 sci_force_enable causes the kernel to set SCI_EN directly
261 on resume from S1/S3 (which is against the ACPI spec,
262 but some broken systems don't work without it).
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263
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
267
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268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
283
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284 ad1848= [HW,OSS]
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
286
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287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
289
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290 advansys= [HW,SCSI]
291 See header of drivers/scsi/advansys.c.
292
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
295
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
a9913044 299
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300 agp= [AGP]
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
305
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306 aha152x= [HW,SCSI]
307 See Documentation/scsi/aha152x.txt.
308
309 aha1542= [HW,SCSI]
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
311
312 aic7xxx= [HW,SCSI]
313 See Documentation/scsi/aic7xxx.txt.
314
315 aic79xx= [HW,SCSI]
316 See Documentation/scsi/aic79xx.txt.
317
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318 alignment= [KNL,ARM]
319 Allow the default userspace alignment fault handler
320 behaviour to be specified. Bit 0 enables warnings,
321 bit 1 enables fixups, and bit 2 sends a segfault.
322
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323 amd_iommu= [HW,X86-84]
324 Pass parameters to the AMD IOMMU driver in the system.
325 Possible values are:
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326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
329 is a lot of faster
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330 off - do not initialize any AMD IOMMU found in
331 the system
afa9fdc2 332
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333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
335 Format: <a>,<b>
336 See also Documentation/kernel/input/joystick.txt
337
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
342
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343 apc= [HW,SPARC]
344 Power management functions (SPARCstation-4/5 + deriv.)
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345 Format: noidle
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
349
ca1eda2d 350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
c8facbb6 351 Change the output verbosity whilst booting
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352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
a9913044 355
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356 autoconf= [IPV6]
357 See Documentation/networking/ipv6.txt.
358
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359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
367
1da177e4 368 apm= [APM] Advanced Power Management
71f77055 369 See header of arch/x86/kernel/apm_32.c.
1da177e4 370
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371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
373
374 ataflop= [HW,M68k]
375
376 atarimouse= [HW,MOUSE] Atari Mouse
377
378 atascsi= [HW,SCSI] Atari SCSI
379
380 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
381 EzKey and similar keyboards
382
383 atkbd.reset= [HW] Reset keyboard during initialization
384
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385 atkbd.set= [HW] Select keyboard code set
386 Format: <int> (2 = AT (default), 3 = PS/2)
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387
388 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 keyboards
390
391 atkbd.softraw= [HW] Choose between synthetic and real raw mode
392 Format: <bool> (0 = real, 1 = synthetic (default))
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393
394 atkbd.softrepeat= [HW]
395 Use software keyboard repeat
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396
397 autotest [IA64]
398
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399 baycom_epp= [HW,AX25]
400 Format: <io>,<mode>
a9913044 401
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402 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
403 Format: <io>,<mode>
404 See header of drivers/net/hamradio/baycom_par.c.
405
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406 baycom_ser_fdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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408 Format: <io>,<irq>,<mode>[,<baud>]
409 See header of drivers/net/hamradio/baycom_ser_fdx.c.
410
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411 baycom_ser_hdx= [HW,AX25]
412 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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413 Format: <io>,<irq>,<mode>
414 See header of drivers/net/hamradio/baycom_ser_hdx.c.
415
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416 boot_delay= Milliseconds to delay each printk during boot.
417 Values larger than 10 seconds (10000) are changed to
418 no delay (0).
419 Format: integer
420
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421 bootmem_debug [KNL] Enable bootmem allocator debug messages.
422
1da177e4 423 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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424 bttv.radio= Most important insmod options are available as
425 kernel args too.
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426 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
428
429 BusLogic= [HW,SCSI]
430 See drivers/scsi/BusLogic.c, comment before function
431 BusLogic_ParseDriverOptions().
432
433 c101= [NET] Moxa C101 synchronous serial card
434
cd4f0ef7 435 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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436 Sometimes CPU hardware bugs make them report the cache
437 size incorrectly. The kernel will attempt work arounds
438 to fix known problems, but for some CPUs it is not
439 possible to determine what the correct size should be.
440 This option provides an override for these situations.
441
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442 capability.disable=
443 [SECURITY] Disable capabilities. This would normally
444 be used only if an alternative security model is to be
445 configured. Potentially dangerous and should only be
446 used if you are entirely sure of the consequences.
447
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448 ccw_timeout_log [S390]
449 See Documentation/s390/CommonIO for details.
1da177e4 450
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451 cgroup_disable= [KNL] Disable a particular controller
452 Format: {name of the controller(s) to disable}
453 {Currently supported controllers - "memory"}
454
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455 checkreqprot [SELINUX] Set initial checkreqprot flag value.
456 Format: { "0" | "1" }
457 See security/selinux/Kconfig help text.
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458 0 -- check protection applied by kernel (includes
459 any implied execute protection).
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460 1 -- check protection requested by application.
461 Default value is set via a kernel config option.
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462 Value can be changed at runtime via
463 /selinux/checkreqprot.
464
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465 cio_ignore= [S390]
466 See Documentation/s390/CommonIO for details.
467
cd4f0ef7 468 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
734efb46 469 [Deprecated]
3f6dee9b 470 Forces specified clocksource (if available) to be used
734efb46 471 when calculating gettimeofday(). If specified
3f6dee9b 472 clocksource is not available, it defaults to PIT.
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473 Format: { pit | tsc | cyclone | pmtmr }
474
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475 clocksource= [GENERIC_TIME] Override the default clocksource
476 Format: <string>
477 Override the default clocksource and use the clocksource
478 with the name specified.
479 Some clocksource names to choose from, depending on
480 the platform:
481 [all] jiffies (this is the base, fallback clocksource)
482 [ACPI] acpi_pm
483 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
484 pxa_timer,timer3,32k_counter,timer0_1
485 [AVR32] avr32
cd4f0ef7 486 [X86-32] pit,hpet,tsc,vmi-timer;
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487 scx200_hrt on Geode; cyclone on IBM x440
488 [MIPS] MIPS
489 [PARISC] cr16
490 [S390] tod
491 [SH] SuperH
492 [SPARC64] tick
493 [X86-64] hpet,tsc
494
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495 clearcpuid=BITNUM [X86]
496 Disable CPUID feature X for the kernel. See
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497 arch/x86/include/asm/cpufeature.h for the valid bit
498 numbers. Note the Linux specific bits are not necessarily
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499 stable over kernel options, but the vendor specific
500 ones should be.
501 Also note that user programs calling CPUID directly
502 or using the feature without checking anything
503 will still see it. This just prevents it from
504 being used by the kernel or shown in /proc/cpuinfo.
505 Also note the kernel might malfunction if you disable
506 some critical bits.
507
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508 cmo_free_hint= [PPC] Format: { yes | no }
509 Specify whether pages are marked as being inactive
510 when they are freed. This is used in CMO environments
511 to determine OS memory pressure for page stealing by
512 a hypervisor.
513 Default: yes
514
6cececfc 515 code_bytes [X86] How many bytes of object code to print
a25bd949 516 in an oops report.
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517 Range: 0 - 8192
518 Default: 64
519
1da177e4 520 com20020= [HW,NET] ARCnet - COM20020 chipset
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521 Format:
522 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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523
524 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
525 Format: <io>[,<irq>]
526
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527 com90xx= [HW,NET]
528 ARCnet - COM90xx chipset (memory-mapped buffers)
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LT
529 Format: <io>[,<irq>[,<memstart>]]
530
531 condev= [HW,S390] console device
532 conmode=
a9913044 533
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534 console= [KNL] Output console device and options.
535
536 tty<n> Use the virtual console device <n>.
537
538 ttyS<n>[,options]
f1a1c2dc 539 ttyUSB0[,options]
1da177e4 540 Use the specified serial port. The options are of
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RD
541 the form "bbbbpnf", where "bbbb" is the baud rate,
542 "p" is parity ("n", "o", or "e"), "n" is number of
543 bits, and "f" is flow control ("r" for RTS or
544 omit it). Default is "9600n8".
545
546 See Documentation/serial-console.txt for more
547 information. See
548 Documentation/networking/netconsole.txt for an
549 alternative.
1da177e4 550
18a8bd94
YL
551 uart[8250],io,<addr>[,options]
552 uart[8250],mmio,<addr>[,options]
1da177e4
LT
553 Start an early, polled-mode console on the 8250/16550
554 UART at the specified I/O port or MMIO address,
555 switching to the matching ttyS device later. The
556 options are the same as for ttyS, above.
557
f7511d5f
ST
558 If the device connected to the port is not a TTY but a braille
559 device, prepend "brl," before the device type, for instance
560 console=brl,ttyS0
561 For now, only VisioBraille is supported.
562
f324edc8
DM
563 consoleblank= [KNL] The console blank (screen saver) timeout in
564 seconds. Defaults to 10*60 = 10mins. A value of 0
565 disables the blank timer.
566
4cb0e11b
HK
567 coredump_filter=
568 [KNL] Change the default value for
569 /proc/<pid>/coredump_filter.
570 See also Documentation/filesystems/proc.txt.
571
1da177e4 572 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
a9913044
RD
573 Format:
574 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
1da177e4 575
dc009d92
EB
576 crashkernel=nn[KMG]@ss[KMG]
577 [KNL] Reserve a chunk of physical memory to
578 hold a kernel to switch to with kexec on panic.
579
fb391599
BW
580 crashkernel=range1:size1[,range2:size2,...][@offset]
581 [KNL] Same as above, but depends on the memory
582 in the running system. The syntax of range is
583 start-[end] where start and end are both
584 a memory unit (amount[KMG]). See also
585 Documentation/kdump/kdump.txt for a example.
586
1da177e4
LT
587 cs89x0_dma= [HW,NET]
588 Format: <dma>
589
590 cs89x0_media= [HW,NET]
591 Format: { rj45 | aui | bnc }
a9913044 592
a9913044 593 dasd= [HW,NET]
1da177e4
LT
594 See header of drivers/s390/block/dasd_devmap.c.
595
596 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
597 (one device per port)
598 Format: <port#>,<type>
599 See also Documentation/input/joystick-parport.txt
600
601 debug [KNL] Enable kernel debugging (events log level).
602
cae2ed9a
IM
603 debug_locks_verbose=
604 [KNL] verbose self-tests
605 Format=<0|1>
606 Print debugging info while doing the locking API
607 self-tests.
608 We default to 0 (no extra messages), setting it to
609 1 will print _a lot_ more information - normally
610 only useful to kernel developers.
611
3ac7fe5a
TG
612 debug_objects [KNL] Enable object debugging
613
3e8ebb5c
KM
614 no_debug_objects
615 [KNL] Disable object debugging
616
d3af01f1
TG
617 debugpat [X86] Enable PAT debugging
618
2d27a966 619 decnet.addr= [HW,NET]
1da177e4
LT
620 Format: <area>[,<node>]
621 See also Documentation/networking/decnet.txt.
622
0cb55ad2
RD
623 default_hugepagesz=
624 [same as hugepagesz=] The size of the default
625 HugeTLB page size. This is the size represented by
626 the legacy /proc/ hugepages APIs, used for SHM, and
627 default size when mounting hugetlbfs filesystems.
628 Defaults to the default architecture's huge page size
629 if not specified.
55ff9780 630
1da177e4
LT
631 dhash_entries= [KNL]
632 Set number of hash buckets for dentry cache.
a9913044 633
1da177e4
LT
634 digi= [HW,SERIAL]
635 IO parameters + enable/disable command.
636
637 digiepca= [HW,SERIAL]
638 See drivers/char/README.epca and
31c00fc1 639 Documentation/serial/digiepca.txt.
1da177e4 640
b0f83b28
BH
641 disable= [IPV6]
642 See Documentation/networking/ipv6.txt.
643
644 disable_ipv6= [IPV6]
645 See Documentation/networking/ipv6.txt.
646
95ffa243 647 disable_mtrr_cleanup [X86]
95ffa243
YL
648 The kernel tries to adjust MTRR layout from continuous
649 to discrete, to make X server driver able to add WB
0cb55ad2 650 entry later. This parameter disables that.
95ffa243 651
093af8d7 652 disable_mtrr_trim [X86, Intel and AMD only]
99fc8d42
JB
653 By default the kernel will trim any uncacheable
654 memory out of your available memory pool based on
655 MTRR settings. This parameter disables that behavior,
656 possibly causing your machine to run very slowly.
657
6cececfc 658 disable_timer_pin_1 [X86]
0cb55ad2
RD
659 Disable PIN 1 of APIC timer
660 Can be useful to work around chipset bugs.
661
1da177e4
LT
662 dmasound= [HW,OSS] Sound subsystem buffers
663
0cb55ad2
RD
664 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
665 this option disables the debugging code at boot.
666
667 dma_debug_entries=<number>
668 This option allows to tune the number of preallocated
669 entries for DMA-API debugging code. One entry is
670 required per DMA-API allocation. Use this if the
671 DMA-API debugging code disables itself because the
672 architectural default is too low.
673
1745de5e
JR
674 dma_debug_driver=<driver_name>
675 With this option the DMA-API debugging driver
676 filter feature can be enabled at boot time. Just
677 pass the driver to filter for as the parameter.
678 The filter can be disabled or changed to another
679 driver later using sysfs.
680
1da177e4
LT
681 dscc4.setup= [NET]
682
683 dtc3181e= [HW,SCSI]
684
0cb55ad2
RD
685 dynamic_printk Enables pr_debug()/dev_dbg() calls if
686 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
687 These can also be switched on/off via
688 <debugfs>/dynamic_printk/modules
689
690 earlycon= [KNL] Output early console device and options.
691 uart[8250],io,<addr>[,options]
692 uart[8250],mmio,<addr>[,options]
693 Start an early, polled-mode console on the 8250/16550
694 UART at the specified I/O port or MMIO address.
695 The options are the same as for ttyS, above.
696
6cececfc 697 earlyprintk= [X86,SH,BLACKFIN]
1da177e4
LT
698 earlyprintk=vga
699 earlyprintk=serial[,ttySn[,baudrate]]
ea3acb19 700 earlyprintk=ttySn[,baudrate]
9780bc41 701 earlyprintk=dbgp[debugController#]
1da177e4 702
a9913044 703 Append ",keep" to not disable it when the real console
1da177e4
LT
704 takes over.
705
5c05917e 706 Only vga or serial or usb debug port at a time.
1da177e4
LT
707
708 Currently only ttyS0 and ttyS1 are supported.
709
710 Interaction with the standard serial driver is not
711 very good.
712
713 The VGA output is eventually overwritten by the real
714 console.
715
9731191f
JW
716 ekgdboc= [X86,KGDB] Allow early kernel console debugging
717 ekgdboc=kbd
718
719 This is desgined to be used in conjunction with
720 the boot argument: earlyprintk=vga
721
1da177e4
LT
722 eata= [HW,SCSI]
723
1da177e4 724 edd= [EDD]
8c4dd606 725 Format: {"off" | "on" | "skip[mbr]"}
1da177e4 726
1da177e4
LT
727 eisa_irq_edge= [PARISC,HW]
728 See header of drivers/parisc/eisa.c.
729
cd4f0ef7 730 elanfreq= [X86-32]
1da177e4 731 See comment before function elanfreq_setup() in
71f77055 732 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1da177e4
LT
733
734 elevator= [IOSCHED]
16ab3adf 735 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
a9913044
RD
736 See Documentation/block/as-iosched.txt and
737 Documentation/block/deadline-iosched.txt for details.
738
6cececfc 739 elfcorehdr= [IA64,PPC,SH,X86]
a9913044 740 Specifies physical address of start of kernel core
aac04b32
VG
741 image elf header. Generally kexec loader will
742 pass this option to capture kernel.
743 See Documentation/kdump/kdump.txt for details.
1da177e4 744
0cb55ad2
RD
745 enable_mtrr_cleanup [X86]
746 The kernel tries to adjust MTRR layout from continuous
747 to discrete, to make X server driver able to add WB
748 entry later. This parameter enables that.
749
ca1eda2d 750 enable_timer_pin_1 [X86]
0cb55ad2
RD
751 Enable PIN 1 of APIC timer
752 Can be useful to work around chipset bugs
753 (in particular on some ATI chipsets).
754 The kernel tries to set a reasonable default.
755
1da177e4
LT
756 enforcing [SELINUX] Set initial enforcing status.
757 Format: {"0" | "1"}
758 See security/selinux/Kconfig help text.
759 0 -- permissive (log only, no denials).
760 1 -- enforcing (deny and log).
761 Default value is 0.
762 Value can be changed at runtime via /selinux/enforce.
763
1da177e4
LT
764 ether= [HW,NET] Ethernet cards parameters
765 This option is obsoleted by the "netdev=" option, which
766 has equivalent usage. See its documentation for details.
767
768 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
769 Format: <io>[,<irq>]
770
de1ba09b
AM
771 failslab=
772 fail_page_alloc=
773 fail_make_request=[KNL]
774 General fault injection mechanism.
775 Format: <interval>,<probability>,<space>,<times>
776 See also /Documentation/fault-injection/.
777
1da177e4
LT
778 fd_mcs= [HW,SCSI]
779 See header of drivers/scsi/fd_mcs.c.
780
781 fdomain= [HW,SCSI]
782 See header of drivers/scsi/fdomain.c.
783
784 floppy= [HW]
31c00fc1 785 See Documentation/blockdev/floppy.txt.
1da177e4 786
f13ae30e
AC
787 force_pal_cache_flush
788 [IA-64] Avoid check_sal_cache_flush which may hang on
789 buggy SAL_CACHE_FLUSH implementations. Using this
790 parameter will force ia64_sal_cache_flush to call
791 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
792
d9e54076 793 ftrace=[tracer]
2af15d6a 794 [FTRACE] will set and start the specified tracer
d9e54076
PZ
795 as early as possible in order to facilitate early
796 boot debugging.
797
cecbca96 798 ftrace_dump_on_oops[=orig_cpu]
2af15d6a 799 [FTRACE] will dump the trace buffers on oops.
cecbca96
FW
800 If no parameter is passed, ftrace will dump
801 buffers of all CPUs, but if you pass orig_cpu, it will
802 dump only the buffer of the CPU that triggered the
803 oops.
2af15d6a
SR
804
805 ftrace_filter=[function-list]
806 [FTRACE] Limit the functions traced by the function
807 tracer at boot up. function-list is a comma separated
808 list of functions. This list can be changed at run
809 time by the set_ftrace_filter file in the debugfs
810 tracing directory.
811
812 ftrace_notrace=[function-list]
813 [FTRACE] Do not trace the functions specified in
814 function-list. This list can be changed at run time
815 by the set_ftrace_notrace file in the debugfs
816 tracing directory.
d9e54076 817
369bc18f
SA
818 ftrace_graph_filter=[function-list]
819 [FTRACE] Limit the top level callers functions traced
820 by the function graph tracer at boot up.
821 function-list is a comma separated list of functions
822 that can be changed at run time by the
823 set_graph_function file in the debugfs tracing directory.
824
1da177e4
LT
825 gamecon.map[2|3]=
826 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
827 support via parallel port (up to 5 devices per port)
828 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
829 See also Documentation/input/joystick-parport.txt
830
831 gamma= [HW,DRM]
832
aaf23042
YL
833 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
834 Format: off | on
835 default: on
836
2521f2c2
PO
837 gcov_persist= [GCOV] When non-zero (default), profiling data for
838 kernel modules is saved and remains accessible via
839 debugfs, even when the module is unloaded/reloaded.
840 When zero, profiling data is discarded and associated
841 debugfs files are removed at module unload time.
842
1da177e4
LT
843 gdth= [HW,SCSI]
844 See header of drivers/scsi/gdth.c.
845
846 gpt [EFI] Forces disk with valid GPT signature but
847 invalid Protective MBR to be treated as GPT.
848
1da177e4
LT
849 gvp11= [HW,SCSI]
850
851 hashdist= [KNL,NUMA] Large hashes allocated during boot
852 are distributed across NUMA nodes. Defaults on
429aa0fc 853 for 64bit NUMA, off otherwise.
a9913044 854 Format: 0 | 1 (for off | on)
1da177e4
LT
855
856 hcl= [IA-64] SGI's Hardware Graph compatibility layer
857
858 hd= [EIDE] (E)IDE hard drive subsystem geometry
859 Format: <cyl>,<head>,<sect>
860
1da177e4
LT
861 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
862 size of <nn>. This works even on boxes that have no
863 highmem otherwise. This also works to reduce highmem
864 size on bigger boxes.
865
54cdfdb4
TG
866 highres= [KNL] Enable/disable high resolution timer mode.
867 Valid parameters: "on", "off"
868 Default: "on"
869
1da177e4
LT
870 hisax= [HW,ISDN]
871 See Documentation/isdn/README.HiSax.
872
0cb55ad2
RD
873 hlt [BUGS=ARM,SH]
874
875 hpet= [X86-32,HPET] option to control HPET usage
876 Format: { enable (default) | disable | force |
877 verbose }
878 disable: disable HPET and use PIT instead
879 force: allow force enabled of undocumented chips (ICH4,
880 VIA, nVidia)
881 verbose: show contents of HPET registers during setup
882
b4718e62
AK
883 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
884 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
0d9ea754
JT
885 On x86-64 and powerpc, this option can be specified
886 multiple times interleaved with hugepages= to reserve
887 huge pages of different sizes. Valid pages sizes on
888 x86-64 are 2M (when the CPU supports "pse") and 1G
889 (when the CPU supports the "pdpe1gb" cpuinfo flag)
b4718e62
AK
890 Note that 1GB pages can only be allocated at boot time
891 using hugepages= and not freed afterwards.
6902aa84 892
555d61d6
HB
893 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
894 terminal devices. Valid values: 0..8
431429ff
HB
895 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
896 If specified, z/VM IUCV HVC accepts connections
897 from listed z/VM user IDs only.
cef7125d 898
3a853fb9 899 i2c_bus= [HW] Override the default board specific I2C bus speed
7954763b
JN
900 or register an additional I2C bus that is not
901 registered from board initialization code.
3a853fb9
JN
902 Format:
903 <bus_id>,<clkrate>
904
36d95739 905 i8042.debug [HW] Toggle i8042 debug mode
1da177e4 906 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
907 i8042.dumbkbd [HW] Pretend that controller can only read data from
908 keyboard and cannot control its state
1da177e4
LT
909 (Don't attempt to blink the leds)
910 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 911 i8042.nokbd [HW] Don't check/create keyboard port
75d08c78
JK
912 i8042.noloop [HW] Disable the AUX Loopback command while probing
913 for the AUX port
1da177e4
LT
914 i8042.nomux [HW] Don't check presence of an active multiplexing
915 controller
916 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
917 controllers
918 i8042.panicblink=
919 [HW] Frequency with which keyboard LEDs should blink
920 when kernel panics (default is 0.5 sec)
921 i8042.reset [HW] Reset the controller during init and cleanup
922 i8042.unlock [HW] Unlock (ignore) the keylock
923
924 i810= [HW,DRM]
925
e70c9d5e
DT
926 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
927 indicates that the driver is running on unsupported
928 hardware.
1da177e4
LT
929 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
930 does not match list of supported models.
931 i8k.power_status
932 [HW] Report power status in /proc/i8k
933 (disabled by default)
934 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
935 capability is set.
936
937 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
938 See Documentation/mca.txt.
939
940 icn= [HW,ISDN]
941 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
942
0af80c04
DF
943 ide-core.nodma= [HW] (E)IDE subsystem
944 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
075affcb
BZ
945 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
946 .cdrom .chs .ignore_cable are additional options
1c10e938 947 See Documentation/ide/ide.txt.
1da177e4 948
0cb55ad2
RD
949 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
950 Claim all unknown PCI IDE storage controllers.
951
f039b754 952 idle= [X86]
ada9cfdd
RD
953 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
954 Poll forces a polling idle loop that can slightly
955 improve the performance of waking up a idle CPU, but
956 will use a lot of power and make the system run hot.
957 Not recommended.
958 idle=mwait: On systems which support MONITOR/MWAIT but
959 the kernel chose to not use it because it doesn't save
960 as much power as a normal idle loop, use the
961 MONITOR/MWAIT idle loop anyways. Performance should be
962 the same as idle=poll.
963 idle=halt: Halt is forced to be used for CPU idle.
c1e3b377 964 In such case C2/C3 won't be used again.
ada9cfdd 965 idle=nomwait: Disable mwait for CPU C-states
a9913044 966
79290822
IM
967 ignore_loglevel [KNL]
968 Ignore loglevel setting - this will print /all/
969 kernel messages to the console. Useful for debugging.
970
1da177e4
LT
971 ihash_entries= [KNL]
972 Set number of hash buckets for inode cache.
973
3323eec9
MZ
974 ima_audit= [IMA]
975 Format: { "0" | "1" }
976 0 -- integrity auditing messages. (Default)
977 1 -- enable informational integrity auditing messages.
978
979 ima_hash= [IMA]
a9ed83a5 980 Format: { "sha1" | "md5" }
3323eec9
MZ
981 default: "sha1"
982
5789ba3b
EP
983 ima_tcb [IMA]
984 Load a policy which meets the needs of the Trusted
985 Computing Base. This means IMA will measure all
986 programs exec'd, files mmap'd for exec, and all files
987 opened for read by uid=0.
988
1da177e4
LT
989 in2000= [HW,SCSI]
990 See header of drivers/scsi/in2000.c.
991
992 init= [KNL]
993 Format: <full_path>
994 Run specified binary instead of /sbin/init as init
995 process.
996
997 initcall_debug [KNL] Trace initcalls as they are executed. Useful
998 for working out where the kernel is dying during
999 startup.
1000
1001 initrd= [BOOT] Specify the location of the initial ramdisk
1002
1003 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1004 Format: <irq>
1005
ba395927 1006 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
0cd5c3c8
KM
1007 on
1008 Enable intel iommu driver.
ba395927
KA
1009 off
1010 Disable intel iommu driver.
1011 igfx_off [Default Off]
1012 By default, gfx is mapped as normal device. If a gfx
1013 device has a dedicated DMAR unit, the DMAR unit is
1014 bypassed by not enabling DMAR with this option. In
1015 this case, gfx device will use physical address for
1016 DMA.
7d3b03ce
KA
1017 forcedac [x86_64]
1018 With this option iommu will not optimize to look
1019 for io virtual address below 32 bit forcing dual
1020 address cycle on pci bus for cards supporting greater
1021 than 32 bit addressing. The default is to look
1022 for translation below 32 bit and if not available
1023 then look in the higher range.
5e0d2a6f 1024 strict [Default Off]
1025 With this option on every unmap_single operation will
1026 result in a hardware IOTLB flush operation as opposed
1027 to batching them for performance.
ba395927 1028
0cb55ad2
RD
1029 inttest= [IA64]
1030
1031 iomem= Disable strict checking of access to MMIO memory
1032 strict regions from userspace.
1033 relaxed
1034
1035 iommu= [x86]
1036 off
1037 force
1038 noforce
1039 biomerge
1040 panic
1041 nopanic
1042 merge
1043 nomerge
1044 forcesac
1045 soft
4ed0d3e6 1046 pt [x86, IA64]
0cb55ad2
RD
1047
1048 io7= [HW] IO7 for Marvel based alpha systems
1049 See comment before marvel_specify_io7 in
1050 arch/alpha/kernel/core_marvel.c.
1051
6cececfc 1052 io_delay= [X86] I/O delay method
6e7c4025
IM
1053 0x80
1054 Standard port 0x80 based delay
1055 0xed
1056 Alternate port 0xed based delay (needed on some systems)
b02aae9c 1057 udelay
6e7c4025
IM
1058 Simple two microseconds delay
1059 none
1060 No delay
b02aae9c 1061
1da177e4 1062 ip= [IP_PNP]
dc7a0816 1063 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1064
1065 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
c8facbb6
RD
1066 See comment before ip2_setup() in
1067 drivers/char/ip2/ip2base.c.
1da177e4
LT
1068
1069 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1070 See header of drivers/scsi/ips.c.
1071
200803df
AC
1072 irqfixup [HW]
1073 When an interrupt is not handled search all handlers
1074 for it. Intended to get systems with badly broken
1075 firmware running.
1076
1077 irqpoll [HW]
1078 When an interrupt is not handled search all handlers
1079 for it. Also check all handlers each timer
1080 interrupt. Intended to get systems with badly broken
1081 firmware running.
1082
1da177e4 1083 isapnp= [ISAPNP]
a9913044 1084 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
1085
1086 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
1087 Format:
1088 <cpu number>,...,<cpu number>
1089 or
b225d44e
LZ
1090 <cpu number>-<cpu number>
1091 (must be a positive range in ascending order)
22f2e280
DF
1092 or a mixture
1093 <cpu number>,...,<cpu number>-<cpu number>
b225d44e 1094
1da177e4
LT
1095 This option can be used to specify one or more CPUs
1096 to isolate from the general SMP balancing and scheduling
b225d44e
LZ
1097 algorithms. You can move a process onto or off an
1098 "isolated" CPU via the CPU affinity syscalls or cpuset.
1da177e4
LT
1099 <cpu number> begins at 0 and the maximum value is
1100 "number of CPUs in system - 1".
1101
1102 This option is the preferred way to isolate CPUs. The
a9913044
RD
1103 alternative -- manually setting the CPU mask of all
1104 tasks in the system -- can cause problems and
1105 suboptimal load balancer performance.
1da177e4 1106
a9913044 1107 iucv= [HW,NET]
1da177e4
LT
1108
1109 js= [HW,JOY] Analog joystick
1110 See Documentation/input/joystick.txt.
1111
0cb55ad2
RD
1112 keepinitrd [HW,ARM]
1113
6cececfc 1114 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
ed7ed365
MG
1115 specifies the amount of memory usable by the kernel
1116 for non-movable allocations. The requested amount is
1117 spread evenly throughout all nodes in the system. The
1118 remaining memory in each node is used for Movable
1119 pages. In the event, a node is too small to have both
1120 kernelcore and Movable pages, kernelcore pages will
1121 take priority and other nodes will have a larger number
1122 of kernelcore pages. The Movable zone is used for the
1123 allocation of pages that may be reclaimed or moved
1124 by the page migration subsystem. This means that
1125 HugeTLB pages may not be allocated from this zone.
1126 Note that allocations like PTEs-from-HighMem still
1127 use the HighMem zone if it exists, and the Normal
1128 zone if it does not.
1129
4fe1da4e
JW
1130 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1131 Format: <Controller#>[,poll interval]
1132 The controller # is the number of the ehci usb debug
1133 port as it is probed via PCI. The poll interval is
1134 optional and is the number seconds in between
1135 each poll cycle to the debug port in case you need
1136 the functionality for interrupting the kernel with
1137 gdb or control-c on the dbgp connection. When
1138 not using this parameter you use sysrq-g to break into
1139 the kernel debugger.
1140
84c08fd6 1141 kgdboc= [KGDB,HW] kgdb over consoles.
ada64e4c
JW
1142 Requires a tty driver that supports console polling,
1143 or a supported polling keyboard driver (non-usb).
1144 Serial only format: <serial_device>[,baud]
1145 keyboard only format: kbd
1146 keyboard and serial format: kbd,<serial_device>[,baud]
6cdf6e06 1147
84c08fd6
JW
1148 kgdbwait [KGDB] Stop kernel execution and enter the
1149 kernel debugger at the earliest opportunity.
1150
9bed90c6
FF
1151 kmac= [MIPS] korina ethernet MAC address.
1152 Configure the RouterBoard 532 series on-chip
1153 Ethernet adapter MAC address.
1154
04f70336
CM
1155 kmemleak= [KNL] Boot-time kmemleak enable/disable
1156 Valid arguments: on, off
1157 Default: on
1158
6cececfc 1159 kstack=N [X86] Print N words from the kernel stack
0cb55ad2
RD
1160 in oops dumps.
1161
fef07aae
AP
1162 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1163 Default is 0 (don't ignore, but inject #GP)
1164
1165 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1166 Default is 1 (enabled)
1167
1168 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1169 Default is 0 (off)
1170
1171 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1172 for all guests.
1173 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1174
1175 kvm-intel.bypass_guest_pf=
1176 [KVM,Intel] Disables bypassing of guest page faults
1177 on Intel chips. Default is 1 (enabled)
1178
1179 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1180 (virtualized MMU) support on capable Intel chips.
1181 Default is 1 (enabled)
1182
1183 kvm-intel.emulate_invalid_guest_state=
1184 [KVM,Intel] Enable emulation of invalid guest states
1185 Default is 0 (disabled)
1186
1187 kvm-intel.flexpriority=
1188 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1189 Default is 1 (enabled)
1190
1191 kvm-intel.unrestricted_guest=
1192 [KVM,Intel] Disable unrestricted guest feature
1193 (virtualized real and unpaged mode) on capable
1194 Intel chips. Default is 1 (enabled)
1195
1196 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1197 feature (tagged TLBs) on capable Intel chips.
1198 Default is 1 (enabled)
1199
1da177e4
LT
1200 l2cr= [PPC]
1201
a78bfbfc
RB
1202 l3cr= [PPC]
1203
cd4f0ef7 1204 lapic [X86-32,APIC] Enable the local APIC even if BIOS
a9913044 1205 disabled it.
1da177e4 1206
6cececfc 1207 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
ada9cfdd 1208 in C2 power state.
e585bef8 1209
fcb71f6f
FC
1210 libata.dma= [LIBATA] DMA control
1211 libata.dma=0 Disable all PATA and SATA DMA
1212 libata.dma=1 PATA and SATA Disk DMA only
1213 libata.dma=2 ATAPI (CDROM) DMA only
1214 libata.dma=4 Compact Flash DMA only
1215 Combinations also work, so libata.dma=3 enables DMA
1216 for disks and CDROMs, but not CFs.
20308871
MP
1217
1218 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1219 libata.ignore_hpa=0 keep BIOS limits (default)
1220 libata.ignore_hpa=1 ignore limits, using full disk
fcb71f6f 1221
78e70c23
DJ
1222 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1223 when set.
1224 Format: <int>
1225
33267325
TH
1226 libata.force= [LIBATA] Force configurations. The format is comma
1227 separated list of "[ID:]VAL" where ID is
4c44f309 1228 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
33267325
TH
1229 matching port, link or device. Basically, it matches
1230 the ATA ID string printed on console by libata. If
1231 the whole ID part is omitted, the last PORT and DEVICE
1232 values are used. If ID hasn't been specified yet, the
1233 configuration applies to all ports, links and devices.
1234
1235 If only DEVICE is omitted, the parameter applies to
1236 the port and all links and devices behind it. DEVICE
1237 number of 0 either selects the first device or the
1238 first fan-out link behind PMP device. It does not
1239 select the host link. DEVICE number of 15 selects the
1240 host link and device attached to it.
1241
1242 The VAL specifies the configuration to force. As long
1243 as there's no ambiguity shortcut notation is allowed.
1244 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1245 The following configurations can be forced.
1246
1247 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1248 Any ID with matching PORT is used.
1249
1250 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1251
1252 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1253 udma[/][16,25,33,44,66,100,133] notation is also
1254 allowed.
1255
1256 * [no]ncq: Turn on or off NCQ.
1257
05944bdf
TH
1258 * nohrst, nosrst, norst: suppress hard, soft
1259 and both resets.
1260
33267325
TH
1261 If there are multiple matching configurations changing
1262 the same attribute, the last one is used.
1263
7c4be253
RD
1264 lmb=debug [KNL] Enable lmb debug messages.
1265
1da177e4 1266 load_ramdisk= [RAM] List of ramdisks to load from floppy
31c00fc1 1267 See Documentation/blockdev/ramdisk.txt.
1da177e4 1268
a6b25b67
RD
1269 lockd.nlm_grace_period=P [NFS] Assign grace period.
1270 Format: <integer>
1da177e4 1271
a6b25b67
RD
1272 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1273 Format: <integer>
1274
1275 lockd.nlm_timeout=T [NFS] Assign timeout value.
1276 Format: <integer>
1277
1278 lockd.nlm_udpport=M [NFS] Assign UDP port.
1279 Format: <integer>
1da177e4
LT
1280
1281 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1282 Format: <irq>
1283
1284 loglevel= All Kernel Messages with a loglevel smaller than the
1285 console loglevel will be printed to the console. It can
1286 also be changed with klogd or other programs. The
1287 loglevels are defined as follows:
1288
1289 0 (KERN_EMERG) system is unusable
1290 1 (KERN_ALERT) action must be taken immediately
1291 2 (KERN_CRIT) critical conditions
1292 3 (KERN_ERR) error conditions
1293 4 (KERN_WARNING) warning conditions
1294 5 (KERN_NOTICE) normal but significant condition
1295 6 (KERN_INFO) informational
1296 7 (KERN_DEBUG) debug-level messages
1297
1298 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
1299 Format: { n | nk | nM }
1300 n must be a power of two. The default size
1301 is set in the kernel config file.
1da177e4 1302
accaa24c
RD
1303 logo.nologo [FB] Disables display of the built-in Linux logo.
1304 This may be used to provide more screen space for
1305 kernel log messages and is useful when debugging
1306 kernel boot problems.
1307
1da177e4
LT
1308 lp=0 [LP] Specify parallel ports to use, e.g,
1309 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1310 lp=reset first parallel port). 'lp=0' disables the
1311 lp=auto printer driver. 'lp=reset' (which can be
1312 specified in addition to the ports) causes
1313 attached printers to be reset. Using
1314 lp=port1,port2,... specifies the parallel ports
1315 to associate lp devices with, starting with
1316 lp0. A port specification may be 'none' to skip
1317 that lp device, or a parport name such as
1318 'parport0'. Specifying 'lp=auto' instead of a
1319 port specification list means that device IDs
1320 from each port should be examined, to see if
1321 an IEEE 1284-compliant printer is attached; if
1322 so, the driver will manage that printer.
1323 See also header of drivers/char/lp.c.
1324
1325 lpj=n [KNL]
1326 Sets loops_per_jiffy to given constant, thus avoiding
1327 time-consuming boot-time autodetection (up to 250 ms per
1328 CPU). 0 enables autodetection (default). To determine
1329 the correct value for your kernel, boot with normal
1330 autodetection and see what value is printed. Note that
1331 on SMP systems the preset will be applied to all CPUs,
1332 which is likely to cause problems if your CPUs need
1333 significantly divergent settings. An incorrect value
1334 will cause delays in the kernel to be wrong, leading to
1335 unpredictable I/O errors and other breakage. Although
1336 unlikely, in the extreme case this might damage your
1337 hardware.
1338
1339 ltpc= [NET]
1340 Format: <io>,<irq>,<dma>
1341
a9913044
RD
1342 mac5380= [HW,SCSI] Format:
1343 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 1344
a9913044
RD
1345 machvec= [IA64] Force the use of a particular machine-vector
1346 (machvec) in a generic kernel.
1347 Example: machvec=hpzx1_swiotlb
1da177e4 1348
3209e70e
WZ
1349 machtype= [Loongson] Share the same kernel image file between different
1350 yeeloong laptop.
1351 Example: machtype=lemote-yeeloong-2f-7inch
1352
0cb55ad2
RD
1353 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1354 than or equal to this physical address is ignored.
1da177e4
LT
1355
1356 maxcpus= [SMP] Maximum number of processors that an SMP kernel
61ec7567
LB
1357 should make use of. maxcpus=n : n >= 0 limits the
1358 kernel to using 'n' processors. n=0 is a special case,
1359 it is equivalent to "nosmp", which also disables
1360 the IO APIC.
1da177e4 1361
0cb55ad2
RD
1362 max_loop= [LOOP] Maximum number of loopback devices that can
1363 be mounted
1364 Format: <1-256>
2b2c3750 1365
a9913044 1366 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
1367 Should be between 1 and 2^32-1.
1368
1369 max_report_luns=
a9913044 1370 [SCSI] Maximum number of LUNs received.
1da177e4
LT
1371 Should be between 1 and 16384.
1372
1da177e4
LT
1373 mcatest= [IA-64]
1374
cd4f0ef7 1375 mce [X86-32] Machine Check Exception
1da177e4 1376
71cced6e 1377 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
909dd324 1378
1da177e4
LT
1379 md= [HW] RAID subsystems devices and level
1380 See Documentation/md.txt.
a9913044 1381
1da177e4
LT
1382 mdacon= [MDA]
1383 Format: <first>,<last>
1384 Specifies range of consoles to be captured by the MDA.
a9913044 1385
1da177e4
LT
1386 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1387 Amount of memory to be used when the kernel is not able
1388 to see the whole system memory or for test.
cd4f0ef7 1389 [X86-32] Use together with memmap= to avoid physical
1da177e4
LT
1390 address space collisions. Without memmap= PCI devices
1391 could be placed at addresses belonging to unused RAM.
1392
cd4f0ef7 1393 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1da177e4
LT
1394 memory.
1395
6902aa84
PM
1396 memchunk=nn[KMG]
1397 [KNL,SH] Allow user to override the default size for
1398 per-device physically contiguous DMA buffers.
1399
6cececfc 1400 memmap=exactmap [KNL,X86] Enable setting of an exact
1da177e4
LT
1401 E820 memory map, as specified by the user.
1402 Such memmap=exactmap lines can be constructed based on
1403 BIOS output or other requirements. See the memmap=nn@ss
1404 option description.
1405
1406 memmap=nn[KMG]@ss[KMG]
1407 [KNL] Force usage of a specific region of memory
1408 Region of memory to be used, from ss to ss+nn.
1409
1410 memmap=nn[KMG]#ss[KMG]
1411 [KNL,ACPI] Mark specific memory as ACPI data.
1412 Region of memory to be used, from ss to ss+nn.
1413
1414 memmap=nn[KMG]$ss[KMG]
1415 [KNL,ACPI] Mark specific memory as reserved.
1416 Region of memory to be used, from ss to ss+nn.
1312848e
PM
1417 Example: Exclude memory from 0x18690000-0x1869ffff
1418 memmap=64K$0x18690000
1419 or
1420 memmap=0x10000$0x18690000
1da177e4 1421
9f077871
JF
1422 memory_corruption_check=0/1 [X86]
1423 Some BIOSes seem to corrupt the first 64k of
1424 memory when doing things like suspend/resume.
1425 Setting this option will scan the memory
1426 looking for corruption. Enabling this will
1427 both detect corruption and prevent the kernel
1428 from using the memory being corrupted.
1429 However, its intended as a diagnostic tool; if
1430 repeatable BIOS-originated corruption always
1431 affects the same memory, you can use memmap=
1432 to prevent the kernel from using that memory.
1433
1434 memory_corruption_check_size=size [X86]
1435 By default it checks for corruption in the low
1436 64k, making this memory unavailable for normal
1437 use. Use this parameter to scan for
1438 corruption in more or less memory.
1439
1440 memory_corruption_check_period=seconds [X86]
1441 By default it checks for corruption every 60
1442 seconds. Use this parameter to check at some
1443 other rate. 0 disables periodic checking.
1444
caadbdce 1445 memtest= [KNL,X86] Enable memtest
c64df707 1446 Format: <integer>
c64df707 1447 default : 0 <disable>
9e5f6cf5
AH
1448 Specifies the number of memtest passes to be
1449 performed. Each pass selects another test
1450 pattern from a given set of patterns. Memtest
1451 fills the memory with this pattern, validates
1452 memory contents and reserves bad memory
1453 regions that are detected.
c64df707 1454
1da177e4
LT
1455 meye.*= [HW] Set MotionEye Camera parameters
1456 See Documentation/video4linux/meye.txt.
1457
8f36881b
AS
1458 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1459 Multi-Function General Purpose Timers on AMD Geode
1460 platforms.
1461
e6c4dc6c
WT
1462 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1463 the BIOS has incorrectly applied a workaround. TinyBIOS
1464 version 0.98 is known to be affected, 0.99 fixes the
1465 problem by letting the user disable the workaround.
1466
1da177e4
LT
1467 mga= [HW,DRM]
1468
1c207f95
RD
1469 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1470 physical address is ignored.
1471
39f45d7b
MP
1472 mini2440= [ARM,HW,KNL]
1473 Format:[0..2][b][c][t]
1474 Default: "0tb"
1475 MINI2440 configuration specification:
1476 0 - The attached screen is the 3.5" TFT
1477 1 - The attached screen is the 7" TFT
1478 2 - The VGA Shield is attached (1024x768)
1479 Leaving out the screen size parameter will not load
1480 the TFT driver, and the framebuffer will be left
1481 unconfigured.
1482 b - Enable backlight. The TFT backlight pin will be
1483 linked to the kernel VESA blanking code and a GPIO
1484 LED. This parameter is not necessary when using the
1485 VGA shield.
1486 c - Enable the s3c camera interface.
1487 t - Reserved for enabling touchscreen support. The
1488 touchscreen support is not enabled in the mainstream
1489 kernel as of 2.6.30, a preliminary port can be found
1490 in the "bleeding edge" mini2440 support kernel at
1491 http://repo.or.cz/w/linux-2.6/mini2440.git
1492
6b74ab97
MG
1493 mminit_loglevel=
1494 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1495 parameter allows control of the logging verbosity for
1496 the additional memory initialisation checks. A value
1497 of 0 disables mminit logging and a level of 4 will
1498 log everything. Information is printed at KERN_DEBUG
1499 so loglevel=8 may also need to be specified.
1500
1da177e4
LT
1501 mousedev.tap_time=
1502 [MOUSE] Maximum time between finger touching and
1503 leaving touchpad surface for touch to be considered
1504 a tap and be reported as a left button click (for
1505 touchpads working in absolute mode only).
1506 Format: <msecs>
1507 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1508 reporting absolute coordinates, such as tablets
1509 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1510 reporting absolute coordinates, such as tablets
1511
6cececfc 1512 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
0cb55ad2
RD
1513 is similar to kernelcore except it specifies the
1514 amount of memory used for migratable allocations.
1515 If both kernelcore and movablecore is specified,
1516 then kernelcore will be at *least* the specified
1517 value but may be more. If movablecore on its own
1518 is specified, the administrator must be careful
1519 that the amount of memory usable for all allocations
1520 is not too small.
1521
1da177e4
LT
1522 mpu401= [HW,OSS]
1523 Format: <io>,<irq>
1524
1525 MTD_Partition= [MTD]
1526 Format: <name>,<region-number>,<size>,<offset>
1527
a9913044
RD
1528 MTD_Region= [MTD] Format:
1529 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
1530
1531 mtdparts= [MTD]
c8facbb6 1532 See drivers/mtd/cmdlinepart.c.
1da177e4 1533
5988af23
RH
1534 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1535
1536 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1537
1538 boundary - index of last SLC block on Flex-OneNAND.
1539 The remaining blocks are configured as MLC blocks.
1540 lock - Configure if Flex-OneNAND boundary should be locked.
1541 Once locked, the boundary cannot be changed.
1542 1 indicates lock status, 0 indicates unlock status.
1543
9db829f4
BD
1544 mtdset= [ARM]
1545 ARM/S3C2412 JIVE boot control
1546
1547 See arch/arm/mach-s3c2412/mach-jive.c
1548
1da177e4 1549 mtouchusb.raw_coordinates=
a9913044
RD
1550 [HW] Make the MicroTouch USB driver use raw coordinates
1551 ('y', default) or cooked coordinates ('n')
1da177e4 1552
0cb55ad2 1553 mtrr_chunk_size=nn[KMG] [X86]
19f59460 1554 used for mtrr cleanup. It is largest continuous chunk
0cb55ad2
RD
1555 that could hold holes aka. UC entries.
1556
1557 mtrr_gran_size=nn[KMG] [X86]
1558 Used for mtrr cleanup. It is granularity of mtrr block.
1559 Default is 1.
1560 Large value could prevent small alignment from
1561 using up MTRRs.
1562
1563 mtrr_spare_reg_nr=n [X86]
1564 Format: <integer>
1565 Range: 0,7 : spare reg number
1566 Default : 1
1567 Used for mtrr cleanup. It is spare mtrr entries number.
1568 Set to 2 or more if your graphical card needs more.
1569
1da177e4
LT
1570 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1571
1572 NCR_D700= [HW,SCSI]
1573 See header of drivers/scsi/NCR_D700.c.
1574
1575 ncr5380= [HW,SCSI]
1576
1577 ncr53c400= [HW,SCSI]
1578
1579 ncr53c400a= [HW,SCSI]
1580
1581 ncr53c406a= [HW,SCSI]
1582
1583 ncr53c8xx= [HW,SCSI]
1584
1585 netdev= [NET] Network devices parameters
1586 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1587 Note that mem_start is often overloaded to mean
1588 something different and driver-specific.
a9913044
RD
1589 This usage is only documented in each driver source
1590 file if at all.
1591
58401572
KPO
1592 nf_conntrack.acct=
1593 [NETFILTER] Enable connection tracking flow accounting
1594 0 to disable accounting
1595 1 to enable accounting
1596 Default value depends on CONFIG_NF_CT_ACCT that is
1597 going to be removed in 2.6.29.
1598
1da177e4 1599 nfsaddrs= [NFS]
dc7a0816 1600 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4
LT
1601
1602 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
dc7a0816 1603 See Documentation/filesystems/nfs/nfsroot.txt.
1da177e4 1604
a72b4422
TM
1605 nfs.callback_tcpport=
1606 [NFS] set the TCP port on which the NFSv4 callback
1607 channel should listen.
1608
e571cbf1
TM
1609 nfs.cache_getent=
1610 [NFS] sets the pathname to the program which is used
1611 to update the NFS client cache entries.
1612
1613 nfs.cache_getent_timeout=
1614 [NFS] sets the timeout after which an attempt to
1615 update a cache entry is deemed to have failed.
1616
58df095b
TM
1617 nfs.idmap_cache_timeout=
1618 [NFS] set the maximum lifetime for idmapper cache
1619 entries.
1620
f43bf0be
TM
1621 nfs.enable_ino64=
1622 [NFS] enable 64-bit inode numbers.
1623 If zero, the NFS client will fake up a 32-bit inode
1624 number for the readdir() and stat() syscalls instead
1625 of returning the full 64-bit number.
1626 The default is to return 64-bit inode numbers.
1627
1e1030dc 1628 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
e7ba176b
HS
1629 when a NMI is triggered.
1630 Format: [state][,regs][,debounce][,die]
1631
6cececfc 1632 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
5b9a0e14
CG
1633 Format: [panic,][num]
1634 Valid num: 0,1,2
1635 0 - turn nmi_watchdog off
1636 1 - use the IO-APIC timer for the NMI watchdog
1637 2 - use the local APIC for the NMI watchdog using
0cb55ad2
RD
1638 a performance counter. Note: This will use one
1639 performance counter and the local APIC's performance
1640 vector.
1641 When panic is specified, panic when an NMI watchdog
1642 timeout occurs.
1643 This is useful when you use a panic=... timeout and
1644 need the box quickly up again.
5b9a0e14
CG
1645 Instead of 1 and 2 it is possible to use the following
1646 symbolic names: lapic and ioapic
1647 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1da177e4 1648
bff38771
AV
1649 netpoll.carrier_timeout=
1650 [NET] Specifies amount of time (in seconds) that
1651 netpoll should wait for a carrier. By default netpoll
1652 waits 4 seconds.
1653
cd4f0ef7 1654 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1da177e4
LT
1655 emulation library even if a 387 maths coprocessor
1656 is present.
1657
0cb55ad2
RD
1658 no_console_suspend
1659 [HW] Never suspend the console
1660 Disable suspending of consoles during suspend and
1661 hibernate operations. Once disabled, debugging
1662 messages can reach various consoles while the rest
1663 of the system is being put to sleep (ie, while
1664 debugging driver suspend/resume hooks). This may
1665 not work reliably with all consoles, but is known
1666 to work with serial and VGA consoles.
1667
c1aee215
CL
1668 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1669 caches in the slab allocator. Saves per-node memory,
1670 but will impact performance.
3395ee05 1671
a9913044
RD
1672 noalign [KNL,ARM]
1673
1da177e4
LT
1674 noapic [SMP,APIC] Tells the kernel to not make use of any
1675 IOAPICs that may be present in the system.
1676
1da177e4
LT
1677 nobats [PPC] Do not use BATs for mapping kernel lowmem
1678 on "Classic" PPC cores.
1679
1680 nocache [ARM]
a9913044 1681
0cb55ad2
RD
1682 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1683
163ecdff
SN
1684 nodelayacct [KNL] Disable per-task delay accounting
1685
1da177e4
LT
1686 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1687
6902aa84
PM
1688 nodsp [SH] Disable hardware DSP at boot time.
1689
6cececfc 1690 noefi [X86] Disable EFI runtime services support.
8b2cb7a8 1691
1da177e4
LT
1692 noexec [IA-64]
1693
6cececfc 1694 noexec [X86]
f5a1b191 1695 On X86-32 available only on PAE configured kernels.
1da177e4 1696 noexec=on: enable non-executable mappings (default)
f5a1b191
JS
1697 noexec=off: disable non-executable mappings
1698
1699 noexec32 [X86-64]
1700 This affects only 32-bit executables.
1701 noexec32=on: enable non-executable mappings (default)
1702 read doesn't imply executable mappings
1703 noexec32=off: disable non-executable mappings
1704 read implies executable mappings
1da177e4 1705
6902aa84
PM
1706 nofpu [SH] Disable hardware FPU at boot time.
1707
cd4f0ef7 1708 nofxsr [BUGS=X86-32] Disables x86 floating point extended
4f886511
CE
1709 register save and restore. The kernel will only save
1710 legacy floating-point registers on task switch.
1da177e4 1711
0c752a93
SS
1712 noxsave [BUGS=X86] Disables x86 extended register state save
1713 and restore using xsave. The kernel will fallback to
1714 enabling legacy floating-point and sse state.
1715
01a24d2b
PZ
1716 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1717 wfi(ARM) instruction doesn't work correctly and not to
1718 use it. This is also useful when using JTAG debugger.
a9913044 1719
cd4f0ef7 1720 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1da177e4
LT
1721 instruction doesn't work correctly and not to
1722 use it.
1723
1f29fae2
SH
1724 no_file_caps Tells the kernel not to honor file capabilities. The
1725 only way then for a file to be executed with privilege
1726 is to be setuid root or executed by root.
1727
1da177e4
LT
1728 nohalt [IA-64] Tells the kernel not to use the power saving
1729 function PAL_HALT_LIGHT when idle. This increases
1730 power-consumption. On the positive side, it reduces
1731 interrupt wake-up latency, which may improve performance
1732 in certain environments such as networked servers or
1733 real-time systems.
1734
79bf2bb3
TG
1735 nohz= [KNL] Boottime enable/disable dynamic ticks
1736 Valid arguments: on, off
1737 Default: on
1738
eeee7853
PM
1739 noiotrap [SH] Disables trapped I/O port accesses.
1740
cd4f0ef7 1741 noirqdebug [X86-32] Disables the code which attempts to detect and
1da177e4
LT
1742 disable unhandled interrupt sources.
1743
6cececfc 1744 no_timer_check [X86,APIC] Disables the code which tests for
8542b200
ZA
1745 broken timer IRQ sources.
1746
1da177e4
LT
1747 noisapnp [ISAPNP] Disables ISA PnP code.
1748
1749 noinitrd [RAM] Tells the kernel not to load any configured
1750 initial RAM disk.
1751
03ea8155
WH
1752 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1753 remapping.
1754
1da177e4
LT
1755 nointroute [IA-64]
1756
0aa366f3
TL
1757 nojitter [IA64] Disables jitter checking for ITC timers.
1758
cd4f0ef7 1759 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1da177e4 1760
cd4f0ef7 1761 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
ad62ca2b 1762
1da177e4
LT
1763 noltlbs [PPC] Do not use large page/tlb entries for kernel
1764 lowmem mapping on PPC40x.
1765
312f1f01
H
1766 nomca [IA-64] Disable machine check abort handling
1767
cd4f0ef7 1768 nomce [X86-32] Machine Check Exception
abe37e5a 1769
83d7384f
AS
1770 nomfgpt [X86-32] Disable Multi-Function General Purpose
1771 Timer usage (for AMD Geode machines).
1772
016ddd9b
JK
1773 nopat [X86] Disable PAT (page attribute table extension of
1774 pagetables) support.
1775
0cb55ad2
RD
1776 norandmaps Don't use address space randomization. Equivalent to
1777 echo 0 > /proc/sys/kernel/randomize_va_space
1778
cd4f0ef7 1779 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
959b4fdf 1780
cd4f0ef7 1781 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
b7fb4af0
JF
1782 with UP alternatives
1783
1da177e4
LT
1784 noresidual [PPC] Don't use residual data on PReP machines.
1785
a9913044
RD
1786 noresume [SWSUSP] Disables resume and restores original swap
1787 space.
1788
1da177e4
LT
1789 no-scroll [VGA] Disables scrollback.
1790 This is required for the Braillex ib80-piezo Braille
1791 reader made by F.H. Papenmeier (Germany).
1792
1793 nosbagart [IA-64]
1794
cd4f0ef7 1795 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
4f886511 1796
61ec7567
LB
1797 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1798 and disable the IO APIC. legacy for "maxcpus=0".
1da177e4 1799
97842216
DJ
1800 nosoftlockup [KNL] Disable the soft-lockup detector.
1801
c077719b 1802 noswapaccount [KNL] Disable accounting of swap in memory resource
21acb9ca 1803 controller. (See Documentation/cgroups/memory.txt)
c077719b 1804
1da177e4
LT
1805 nosync [HW,M68K] Disables sync negotiation for all devices.
1806
cd4f0ef7 1807 notsc [BUGS=X86-32] Disable Time Stamp Counter
1da177e4
LT
1808
1809 nousb [USB] Disable the USB subsystem
1810
1811 nowb [ARM]
a9913044 1812
2b2fd87a
WH
1813 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1814
a6c75b86
FY
1815 nptcg= [IA64] Override max number of concurrent global TLB
1816 purges which is reported from either PAL_VM_SUMMARY or
1817 SAL PALO.
1818
2b633e3f
YL
1819 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1820 could support. nr_cpus=n : n >= 1 limits the kernel to
1821 supporting 'n' processors. Later in runtime you can not
1822 use hotplug cpu feature to put more cpu back to online.
1823 just like you compile the kernel NR_CPUS=n
1824
0cb55ad2
RD
1825 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1826
f0c0b2b8
KH
1827 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1828 one of ['zone', 'node', 'default'] can be specified
1829 This can be set from sysctl after boot.
1830 See Documentation/sysctl/vm.txt for details.
1831
7c4be253
RD
1832 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1833 See Documentation/debugging-via-ohci1394.txt for more
1834 info.
1835
3ef0e1f8
AS
1836 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1837 Rather than timing out after 20 ms if an EC
1838 command is not properly ACKed, override the length
1839 of the timeout. We have interrupts disabled while
1840 waiting for the ACK, so if this is set too high
1841 interrupts *may* be lost!
1842
15ac7afe
TL
1843 omap_mux= [OMAP] Override bootloader pin multiplexing.
1844 Format: <mux_mode0.mode_name=value>...
1845 For example, to override I2C bus2:
1846 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1847
1da177e4
LT
1848 opl3= [HW,OSS]
1849 Format: <io>
1850
1da177e4
LT
1851 oprofile.timer= [HW]
1852 Use timer interrupt instead of performance counters
1853
7e4e0bd5
RR
1854 oprofile.cpu_type= Force an oprofile cpu type
1855 This might be useful if you have an older oprofile
1856 userland or if you want common events.
8d7ff4f2
RR
1857 Format: { arch_perfmon }
1858 arch_perfmon: [X86] Force use of architectural
7e4e0bd5
RR
1859 perfmon on Intel CPUs instead of the
1860 CPU specific event set.
1dcdb5a9 1861
1da177e4
LT
1862 osst= [HW,SCSI] SCSI Tape Driver
1863 Format: <buffer_size>,<write_threshold>
1864 See also Documentation/scsi/st.txt.
1865
1866 panic= [KNL] Kernel behaviour on panic
1867 Format: <timeout>
1868
1869 parkbd.port= [HW] Parallel port number the keyboard adapter is
1870 connected to, default is 0.
1871 Format: <parport#>
1872 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1873 0 for XT, 1 for AT (default is AT).
a9913044
RD
1874 Format: <mode>
1875
1876 parport= [HW,PPT] Specify parallel ports. 0 disables.
1877 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1878 Use 'auto' to force the driver to use any
1879 IRQ/DMA settings detected (the default is to
1880 ignore detected IRQ/DMA settings because of
1881 possible conflicts). You can specify the base
1882 address, IRQ, and DMA settings; IRQ and DMA
1883 should be numbers, or 'auto' (for using detected
1884 settings on that particular port), or 'nofifo'
1885 (to avoid using a FIFO even if it is detected).
1886 Parallel ports are assigned in the order they
1887 are specified on the command line, starting
1888 with parport0.
1889
1890 parport_init_mode= [HW,PPT]
1891 Configure VIA parallel port to operate in
1892 a specific mode. This is necessary on Pegasos
1893 computer where firmware has no options for setting
1894 up parallel port mode and sets it to spp.
1895 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1896 Format: [spp|ps2|epp|ecp|ecpepp]
1897
a9913044
RD
1898 pas2= [HW,OSS] Format:
1899 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1900
1da177e4
LT
1901 pas16= [HW,SCSI]
1902 See header of drivers/scsi/pas16.c.
1903
dd287796
AM
1904 pause_on_oops=
1905 Halt all CPUs after the first oops has been printed for
1906 the specified number of seconds. This is to be used if
1907 your oopses keep scrolling off the screen.
1908
1da177e4
LT
1909 pcbit= [HW,ISDN]
1910
1911 pcd. [PARIDE]
1912 See header of drivers/block/paride/pcd.c.
31c00fc1 1913 See also Documentation/blockdev/paride.txt.
1da177e4 1914
a9913044 1915 pci=option[,option...] [PCI] various PCI subsystem options:
1cc0ca26
BH
1916 earlydump [X86] dump PCI config space before the kernel
1917 changes anything
c0115606 1918 off [X86] don't probe for the PCI bus
cd4f0ef7 1919 bios [X86-32] force use of PCI BIOS, don't access
a9913044
RD
1920 the hardware directly. Use this if your machine
1921 has a non-standard PCI host bridge.
cd4f0ef7 1922 nobios [X86-32] disallow use of PCI BIOS, only direct
a9913044
RD
1923 hardware access methods are allowed. Use this
1924 if you experience crashes upon bootup and you
1925 suspect they are caused by the BIOS.
c0115606 1926 conf1 [X86] Force use of PCI Configuration
a9913044 1927 Mechanism 1.
c0115606 1928 conf2 [X86] Force use of PCI Configuration
a9913044 1929 Mechanism 2.
7f785763
RD
1930 noaer [PCIE] If the PCIEAER kernel config parameter is
1931 enabled, this kernel boot option can be used to
1932 disable the use of PCIE advanced error reporting.
32a2eea7
JG
1933 nodomains [PCI] Disable support for multiple PCI
1934 root domains (aka PCI segments, in ACPI-speak).
6cececfc 1935 nommconf [X86] Disable use of MMCONFIG for PCI
61be6d66 1936 Configuration
12983077
AH
1937 check_enable_amd_mmconf [X86] check for and enable
1938 properly configured MMIO access to PCI
1939 config space on AMD family 10h CPU
309e57df
MW
1940 nomsi [MSI] If the PCI_MSI kernel config parameter is
1941 enabled, this kernel boot option can be used to
1942 disable the use of MSI interrupts system-wide.
a9322f64
SA
1943 noioapicquirk [APIC] Disable all boot interrupt quirks.
1944 Safety option to keep boot IRQs enabled. This
1945 should never be necessary.
9197979b
SA
1946 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1947 primary IO-APIC for bridges that cannot disable
1948 boot IRQs. This fixes a source of spurious IRQs
1949 when the system masks IRQs.
41b9eb26
SA
1950 noioapicreroute [APIC] Disable workaround that uses the
1951 boot IRQ equivalent of an IRQ that connects to
1952 a chipset where boot IRQs cannot be disabled.
1953 The opposite of ioapicreroute.
cd4f0ef7 1954 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
a9913044
RD
1955 routing table. These calls are known to be buggy
1956 on several machines and they hang the machine
1957 when used, but on other computers it's the only
1958 way to get the interrupt routing table. Try
1959 this option if the kernel is unable to allocate
1960 IRQs or discover secondary PCI buses on your
1961 motherboard.
c0115606 1962 rom [X86] Assign address space to expansion ROMs.
a9913044
RD
1963 Use with caution as certain devices share
1964 address decoders between ROMs and other
1965 resources.
c0115606 1966 norom [X86] Do not assign address space to
bb71ad88
GH
1967 expansion ROMs that do not already have
1968 BIOS assigned address ranges.
c0115606 1969 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
a9913044
RD
1970 assigned automatically to PCI devices. You can
1971 make the kernel exclude IRQs of your ISA cards
1972 this way.
c0115606 1973 pirqaddr=0xAAAAA [X86] Specify the physical address
a9913044
RD
1974 of the PIRQ table (normally generated
1975 by the BIOS) if it is outside the
1976 F0000h-100000h range.
c0115606 1977 lastbus=N [X86] Scan all buses thru bus #N. Can be
a9913044
RD
1978 useful if the kernel is unable to find your
1979 secondary buses and you want to tell it
1980 explicitly which ones they are.
c0115606 1981 assign-busses [X86] Always assign all PCI bus
a9913044
RD
1982 numbers ourselves, overriding
1983 whatever the firmware may have done.
c0115606 1984 usepirqmask [X86] Honor the possible IRQ mask stored
a9913044
RD
1985 in the BIOS $PIR table. This is needed on
1986 some systems with broken BIOSes, notably
1987 some HP Pavilion N5400 and Omnibook XE3
1988 notebooks. This will have no effect if ACPI
1989 IRQ routing is enabled.
c0115606 1990 noacpi [X86] Do not use ACPI for IRQ routing
a9913044 1991 or for PCI scanning.
7bc5e3f2
BH
1992 use_crs [X86] Use PCI host bridge window information
1993 from ACPI. On BIOSes from 2008 or later, this
1994 is enabled by default. If you need to use this,
1995 please report a bug.
1996 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1997 If you need to use this, please report a bug.
a9913044
RD
1998 routeirq Do IRQ routing for all PCI devices.
1999 This is normally done in pci_enable_device(),
2000 so this option is a temporary workaround
2001 for broken drivers that don't call it.
13a6ddb0
YL
2002 skip_isa_align [X86] do not align io start addr, so can
2003 handle more pci cards
a9913044
RD
2004 firmware [ARM] Do not re-enumerate the bus but instead
2005 just use the configuration from the
2006 bootloader. This is currently used on
2007 IXP2000 systems where the bus has to be
2008 configured a certain way for adjunct CPUs.
0637a70a
AK
2009 noearly [X86] Don't do any early type 1 scanning.
2010 This might help on some broken boards which
2011 machine check when some devices' config space
2012 is read. But various workarounds are disabled
2013 and some IOMMU drivers will not work.
6b4b78fe
MD
2014 bfsort Sort PCI devices into breadth-first order.
2015 This sorting is done to get a device
2016 order compatible with older (<= 2.4) kernels.
2017 nobfsort Don't sort PCI devices into breadth-first order.
4516a618
AN
2018 cbiosize=nn[KMG] The fixed amount of bus space which is
2019 reserved for the CardBus bridge's IO window.
2020 The default value is 256 bytes.
2021 cbmemsize=nn[KMG] The fixed amount of bus space which is
2022 reserved for the CardBus bridge's memory
2023 window. The default value is 64 megabytes.
32a9a682
YS
2024 resource_alignment=
2025 Format:
2026 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2027 Specifies alignment and device to reassign
2028 aligned memory resources.
2029 If <order of align> is not specified,
2030 PAGE_SIZE is used as alignment.
2031 PCI-PCI bridge can be specified, if resource
2032 windows need to be expanded.
43c16408
AP
2033 ecrc= Enable/disable PCIe ECRC (transaction layer
2034 end-to-end CRC checking).
2035 bios: Use BIOS/firmware settings. This is the
2036 the default.
2037 off: Turn ECRC off
2038 on: Turn ECRC on.
6b4b78fe 2039
e5665a45
CE
2040 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2041 Management.
2042 off Disable ASPM.
2043 force Enable ASPM even on devices that claim not to support it.
2044 WARNING: Forcing ASPM on may cause system lockups.
2045
c7f48656
RW
2046 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2047 off Do not use native PCIe PME signaling.
2048 force Use native PCIe PME signaling even if the BIOS refuses
2049 to allow the kernel to control the relevant PCIe config
2050 registers.
c39fae14
RW
2051 nomsi Do not use MSI for native PCIe PME signaling (this makes
2052 all PCIe root ports use INTx for everything).
c7f48656 2053
1da177e4
LT
2054 pcmv= [HW,PCMCIA] BadgePAD 4
2055
2056 pd. [PARIDE]
31c00fc1 2057 See Documentation/blockdev/paride.txt.
1da177e4
LT
2058
2059 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2060 boot time.
2061 Format: { 0 | 1 }
2062 See arch/parisc/kernel/pdc_chassis.c
2063
f58dc01b 2064 percpu_alloc= Select which percpu first chunk allocator to use.
e933a73f
TH
2065 Currently supported values are "embed" and "page".
2066 Archs may support subset or none of the selections.
2067 See comments in mm/percpu.c for details on each
2068 allocator. This parameter is primarily for debugging
2069 and performance comparison.
fa8a7094 2070
1da177e4 2071 pf. [PARIDE]
31c00fc1 2072 See Documentation/blockdev/paride.txt.
1da177e4
LT
2073
2074 pg. [PARIDE]
31c00fc1 2075 See Documentation/blockdev/paride.txt.
1da177e4
LT
2076
2077 pirq= [SMP,APIC] Manual mp-table setup
71cced6e 2078 See Documentation/x86/i386/IO-APIC.txt.
1da177e4
LT
2079
2080 plip= [PPT,NET] Parallel port network link
2081 Format: { parport<nr> | timid | 0 }
2082 See also Documentation/parport.txt.
2083
de32a243
TG
2084 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2085 Override pmtimer IOPort with a hex value.
2086 e.g. pmtmr=0x508
2087
97ef062b
BH
2088 pnp.debug [PNP]
2089 Enable PNP debug messages. This depends on the
2090 CONFIG_PNP_DEBUG_MESSAGES option.
2091
1da177e4
LT
2092 pnpacpi= [ACPI]
2093 { off }
2094
2095 pnpbios= [ISAPNP]
2096 { on | off | curr | res | no-curr | no-res }
2097
2098 pnp_reserve_irq=
2099 [ISAPNP] Exclude IRQs for the autoconfiguration
2100
2101 pnp_reserve_dma=
2102 [ISAPNP] Exclude DMAs for the autoconfiguration
2103
2104 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 2105 Ranges are in pairs (I/O port base and size).
1da177e4
LT
2106
2107 pnp_reserve_mem=
a9913044
RD
2108 [ISAPNP] Exclude memory regions for the
2109 autoconfiguration.
1da177e4
LT
2110 Ranges are in pairs (memory base and size).
2111
4af94f39
RD
2112 ports= [IP_VS_FTP] IPVS ftp helper module
2113 Default is 21.
2114 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2115 may be specified.
2116 Format: <port>,<port>....
2117
45807a1d
IM
2118 print-fatal-signals=
2119 [KNL] debug: print fatal signals
f84d49b2
NO
2120
2121 If enabled, warn about various signal handling
2122 related application anomalies: too many signals,
2123 too many POSIX.1 timers, fatal signals causing a
2124 coredump - etc.
2125
2126 If you hit the warning due to signal overflow,
2127 you might want to try "ulimit -i unlimited".
2128
45807a1d
IM
2129 default: off.
2130
e84845c4
RD
2131 printk.time= Show timing data prefixed to each printk message line
2132 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2133
0cb55ad2
RD
2134 processor.max_cstate= [HW,ACPI]
2135 Limit processor to maximum C-state
2136 max_cstate=9 overrides any DMI blacklist limit.
2137
2138 processor.nocst [HW,ACPI]
2139 Ignore the _CST method to determine C-states,
2140 instead using the legacy FADT method
2141
1da177e4 2142 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
2143 Format: [schedule,]<number>
2144 Param: "schedule" - profile schedule points.
2145 Param: <number> - step/bucket size as a power of 2 for
2146 statistical time based profiling.
b3da2a73
MG
2147 Param: "sleep" - profile D-state sleeping (millisecs).
2148 Requires CONFIG_SCHEDSTATS
c0fe2e69 2149 Param: "kvm" - profile VM exits.
1da177e4 2150
1da177e4
LT
2151 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2152 before loading.
31c00fc1 2153 See Documentation/blockdev/ramdisk.txt.
1da177e4 2154
a9913044
RD
2155 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2156 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
2157 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2158 per second.
a9913044
RD
2159 psmouse.resetafter= [HW,MOUSE]
2160 Try to reset the device after so many bad packets
1da177e4
LT
2161 (0 = never).
2162 psmouse.resolution=
2163 [HW,MOUSE] Set desired mouse resolution, in dpi.
2164 psmouse.smartscroll=
a9913044 2165 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
2166 0 = disabled, 1 = enabled (default).
2167
2168 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
2169 Format:
2170 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
2171
2172 pt. [PARIDE]
31c00fc1 2173 See Documentation/blockdev/paride.txt.
1da177e4 2174
dc8c8587
KS
2175 pty.legacy_count=
2176 [KNL] Number of legacy pty's. Overwrites compiled-in
2177 default number.
2178
7d2c502f 2179 quiet [KNL] Disable most log messages
a9913044 2180
1da177e4
LT
2181 r128= [HW,DRM]
2182
2183 raid= [HW,RAID]
2184 See Documentation/md.txt.
2185
a9913044 2186 ramdisk_blocksize= [RAM]
31c00fc1 2187 See Documentation/blockdev/ramdisk.txt.
a9913044 2188
1da177e4 2189 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
31c00fc1 2190 See Documentation/blockdev/ramdisk.txt.
1da177e4 2191
24aaef8d
RD
2192 rcupdate.blimit= [KNL,BOOT]
2193 Set maximum number of finished RCU callbacks to process
2194 in one batch.
21a1ea9e 2195
24aaef8d
RD
2196 rcupdate.qhimark= [KNL,BOOT]
2197 Set threshold of queued
21a1ea9e
DS
2198 RCU callbacks over which batch limiting is disabled.
2199
24aaef8d
RD
2200 rcupdate.qlowmark= [KNL,BOOT]
2201 Set threshold of queued RCU callbacks below which
2202 batch limiting is re-enabled.
21a1ea9e 2203
ffdfc409
OJ
2204 rdinit= [KNL]
2205 Format: <full_path>
2206 Run specified binary instead of /init from the ramdisk,
2207 used for early userspace startup. See initrd.
2208
cd4f0ef7 2209 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1da177e4 2210 Format: <reboot_mode>[,<reboot_mode2>[,...]]
ecb08d81 2211 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4 2212
46b6d94e
PJ
2213 relax_domain_level=
2214 [KNL, SMP] Set scheduler's default relax_domain_level.
21acb9ca 2215 See Documentation/cgroups/cpusets.txt.
46b6d94e 2216
1da177e4
LT
2217 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2218
cd4f0ef7 2219 reservetop= [X86-32]
461a9aff
ZA
2220 Format: nn[KMG]
2221 Reserves a hole at the top of the kernel virtual
2222 address space.
2223
7e96287d
VG
2224 reset_devices [KNL] Force drivers to reset the underlying device
2225 during initialization.
2226
a9913044
RD
2227 resume= [SWSUSP]
2228 Specify the partition device for software suspend
1da177e4 2229
ecbd0da1
RW
2230 resume_offset= [SWSUSP]
2231 Specify the offset from the beginning of the partition
2232 given by "resume=" at which the swap header is located,
2233 in <PAGE_SIZE> units (needed only for swap files).
2234 See Documentation/power/swsusp-and-swap-files.txt
2235
0a7b35cb
MN
2236 retain_initrd [RAM] Keep initrd memory after extraction
2237
1da177e4
LT
2238 rhash_entries= [KNL,NET]
2239 Set number of hash buckets for route cache
2240
2241 riscom8= [HW,SERIAL]
2242 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2243
2244 ro [KNL] Mount root device read-only on boot
2245
2246 root= [KNL] Root filesystem
2247
2248 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2249 mount the root filesystem
2250
2251 rootflags= [KNL] Set root filesystem mount option string
2252
2253 rootfstype= [KNL] Set root filesystem type
2254
cc1ed754
PO
2255 rootwait [KNL] Wait (indefinitely) for root device to show up.
2256 Useful for devices that are detected asynchronously
2257 (e.g. USB and MMC devices).
2258
1da177e4
LT
2259 rw [KNL] Mount root device read-write on boot
2260
2261 S [KNL] Run init in single mode
2262
2263 sa1100ir [NET]
2264 See drivers/net/irda/sa1100_ir.c.
2265
1da177e4 2266 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 2267
f6630114
MT
2268 sched_debug [KNL] Enables verbose scheduler debug messages.
2269
1da177e4
LT
2270 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2271 Format: <io>[,<timeout>[,<isapnp>]]
2272
2273 scsi_debug_*= [SCSI]
2274 See drivers/scsi/scsi_debug.c.
2275
2276 scsi_default_dev_flags=
2277 [SCSI] SCSI default device flags
2278 Format: <integer>
2279
2280 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2281 Format: <vendor>:<model>:<flags>
2282 (flags are integer value)
2283
6af6632a
RD
2284 scsi_logging_level= [SCSI] a bit mask of logging levels
2285 See drivers/scsi/scsi_logging.h for bits. Also
2286 settable via sysctl at dev.scsi.logging_level
2287 (/proc/sys/dev/scsi/logging_level).
2288 There is also a nice 'scsi_logging_level' script in the
2289 S390-tools package, available for download at
2290 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1da177e4 2291
3e082a91
MW
2292 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2293 discovered. async scans them in kernel threads,
2294 allowing boot to proceed. none ignores them, expecting
2295 user space to do the scan.
2296
0cb55ad2
RD
2297 security= [SECURITY] Choose a security module to enable at boot.
2298 If this boot parameter is not specified, only the first
2299 security module asking for security registration will be
2300 loaded. An invalid security module name will be treated
2301 as if no module has been chosen.
2302
2303 selinux= [SELINUX] Disable or enable SELinux at boot time.
1da177e4
LT
2304 Format: { "0" | "1" }
2305 See security/selinux/Kconfig help text.
2306 0 -- disable.
2307 1 -- enable.
2308 Default value is set via kernel config option.
2309 If enabled at boot time, /selinux/disable can be used
2310 later to disable prior to initial policy load.
2311
cd4f0ef7 2312 serialnumber [BUGS=X86-32]
1da177e4 2313
1da177e4
LT
2314 shapers= [NET]
2315 Maximal number of shapers.
a9913044 2316
b05f78f5
YL
2317 show_msr= [x86] show boot-time MSR settings
2318 Format: { <integer> }
2319 Show boot-time (BIOS-initialized) MSR settings.
2320 The parameter means the number of CPUs to show,
2321 for example 1 means boot CPU only.
2322
1da177e4
LT
2323 sim710= [SCSI,HW]
2324 See header of drivers/scsi/sim710.c.
2325
2326 simeth= [IA-64]
2327 simscsi=
a9913044 2328
1da177e4
LT
2329 slram= [HW,MTD]
2330
f0630fff
CL
2331 slub_debug[=options[,slabs]] [MM, SLUB]
2332 Enabling slub_debug allows one to determine the
2333 culprit if slab objects become corrupted. Enabling
2334 slub_debug can create guard zones around objects and
2335 may poison objects when not in use. Also tracks the
2336 last alloc / free. For more information see
2337 Documentation/vm/slub.txt.
c1aee215
CL
2338
2339 slub_max_order= [MM, SLUB]
f0630fff
CL
2340 Determines the maximum allowed order for slabs.
2341 A high setting may cause OOMs due to memory
2342 fragmentation. For more information see
2343 Documentation/vm/slub.txt.
c1aee215
CL
2344
2345 slub_min_objects= [MM, SLUB]
f0630fff
CL
2346 The minimum number of objects per slab. SLUB will
2347 increase the slab order up to slub_max_order to
2348 generate a sufficiently large slab able to contain
2349 the number of objects indicated. The higher the number
2350 of objects the smaller the overhead of tracking slabs
2351 and the less frequently locks need to be acquired.
c1aee215
CL
2352 For more information see Documentation/vm/slub.txt.
2353
2354 slub_min_order= [MM, SLUB]
2355 Determines the mininum page order for slabs. Must be
f0630fff 2356 lower than slub_max_order.
c1aee215
CL
2357 For more information see Documentation/vm/slub.txt.
2358
2359 slub_nomerge [MM, SLUB]
f0630fff 2360 Disable merging of slabs with similar size. May be
c1aee215 2361 necessary if there is some reason to distinguish
f0630fff
CL
2362 allocs to different slabs. Debug options disable
2363 merging on their own.
c1aee215
CL
2364 For more information see Documentation/vm/slub.txt.
2365
1da177e4
LT
2366 smart2= [HW]
2367 Format: <io1>[,<io2>[,...,<io8>]]
2368
cd4f0ef7 2369 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
b7fb4af0
JF
2370 attempt to substitute SMP alternatives once at boot.
2371
d0d4f69b
BH
2372 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2373 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2374 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2375 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2376 smsc-ircc2.ircc_irq= [HW] IRQ line
2377 smsc-ircc2.ircc_dma= [HW] DMA channel
2378 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2379 0: Toshiba Satellite 1800 (GP data pin select)
2380 1: Fast pin select (default)
2381 2: ATC IRMode
2382
1da177e4
LT
2383 snd-ad1816a= [HW,ALSA]
2384
2385 snd-ad1848= [HW,ALSA]
2386
2387 snd-ali5451= [HW,ALSA]
2388
2389 snd-als100= [HW,ALSA]
2390
2391 snd-als4000= [HW,ALSA]
2392
2393 snd-azt2320= [HW,ALSA]
2394
2395 snd-cmi8330= [HW,ALSA]
2396
2397 snd-cmipci= [HW,ALSA]
2398
2399 snd-cs4231= [HW,ALSA]
2400
2401 snd-cs4232= [HW,ALSA]
2402
2403 snd-cs4236= [HW,ALSA]
2404
2405 snd-cs4281= [HW,ALSA]
2406
2407 snd-cs46xx= [HW,ALSA]
2408
2409 snd-dt019x= [HW,ALSA]
2410
2411 snd-dummy= [HW,ALSA]
2412
2413 snd-emu10k1= [HW,ALSA]
2414
2415 snd-ens1370= [HW,ALSA]
2416
2417 snd-ens1371= [HW,ALSA]
2418
2419 snd-es968= [HW,ALSA]
2420
2421 snd-es1688= [HW,ALSA]
2422
2423 snd-es18xx= [HW,ALSA]
2424
2425 snd-es1938= [HW,ALSA]
2426
2427 snd-es1968= [HW,ALSA]
2428
2429 snd-fm801= [HW,ALSA]
2430
2431 snd-gusclassic= [HW,ALSA]
2432
2433 snd-gusextreme= [HW,ALSA]
2434
2435 snd-gusmax= [HW,ALSA]
2436
2437 snd-hdsp= [HW,ALSA]
2438
2439 snd-ice1712= [HW,ALSA]
2440
2441 snd-intel8x0= [HW,ALSA]
2442
2443 snd-interwave= [HW,ALSA]
2444
2445 snd-interwave-stb=
2446 [HW,ALSA]
2447
2448 snd-korg1212= [HW,ALSA]
2449
2450 snd-maestro3= [HW,ALSA]
2451
2452 snd-mpu401= [HW,ALSA]
2453
2454 snd-mtpav= [HW,ALSA]
2455
2456 snd-nm256= [HW,ALSA]
2457
2458 snd-opl3sa2= [HW,ALSA]
2459
2460 snd-opti92x-ad1848=
2461 [HW,ALSA]
2462
2463 snd-opti92x-cs4231=
2464 [HW,ALSA]
2465
2466 snd-opti93x= [HW,ALSA]
2467
2468 snd-pmac= [HW,ALSA]
2469
2470 snd-rme32= [HW,ALSA]
2471
2472 snd-rme96= [HW,ALSA]
2473
2474 snd-rme9652= [HW,ALSA]
2475
2476 snd-sb8= [HW,ALSA]
2477
2478 snd-sb16= [HW,ALSA]
2479
2480 snd-sbawe= [HW,ALSA]
2481
2482 snd-serial= [HW,ALSA]
2483
2484 snd-sgalaxy= [HW,ALSA]
2485
2486 snd-sonicvibes= [HW,ALSA]
2487
2488 snd-sun-amd7930=
2489 [HW,ALSA]
2490
2491 snd-sun-cs4231= [HW,ALSA]
2492
2493 snd-trident= [HW,ALSA]
2494
2495 snd-usb-audio= [HW,ALSA,USB]
2496
2497 snd-via82xx= [HW,ALSA]
2498
2499 snd-virmidi= [HW,ALSA]
2500
2501 snd-wavefront= [HW,ALSA]
2502
2503 snd-ymfpci= [HW,ALSA]
a9913044 2504
9c44bc03
IM
2505 softlockup_panic=
2506 [KNL] Should the soft-lockup detector generate panics.
2507
1da177e4
LT
2508 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2509 See Documentation/sonypi.txt
2510
2511 specialix= [HW,SERIAL] Specialix multi-serial port adapter
31c00fc1 2512 See Documentation/serial/specialix.txt.
1da177e4
LT
2513
2514 spia_io_base= [HW,MTD]
2515 spia_fio_base=
2516 spia_pedr=
2517 spia_peddr=
2518
2519 sscape= [HW,OSS]
2520 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 2521
1da177e4
LT
2522 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2523 See Documentation/scsi/st.txt.
2524
f38f1d2a
SR
2525 stacktrace [FTRACE]
2526 Enabled the stack tracer on boot up.
2527
1da177e4
LT
2528 sti= [PARISC,HW]
2529 Format: <num>
2530 Set the STI (builtin display/keyboard on the HP-PARISC
2531 machines) console (graphic card) which should be used
2532 as the initial boot-console.
2533 See also comment in drivers/video/console/sticore.c.
2534
2535 sti_font= [HW]
2536 See comment in drivers/video/console/sticore.c.
2537
2538 stifb= [HW]
2539 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2540
cbf11071
TM
2541 sunrpc.min_resvport=
2542 sunrpc.max_resvport=
2543 [NFS,SUNRPC]
2544 SunRPC servers often require that client requests
2545 originate from a privileged port (i.e. a port in the
2546 range 0 < portnr < 1024).
2547 An administrator who wishes to reserve some of these
2548 ports for other uses may adjust the range that the
2549 kernel's sunrpc client considers to be privileged
2550 using these two parameters to set the minimum and
2551 maximum port values.
2552
42a7fc4a
GB
2553 sunrpc.pool_mode=
2554 [NFS]
2555 Control how the NFS server code allocates CPUs to
2556 service thread pools. Depending on how many NICs
2557 you have and where their interrupts are bound, this
2558 option will affect which CPUs will do NFS serving.
2559 Note: this parameter cannot be changed while the
2560 NFS server is running.
2561
2562 auto the server chooses an appropriate mode
2563 automatically using heuristics
2564 global a single global pool contains all CPUs
2565 percpu one pool for each CPU
2566 pernode one pool for each NUMA node (equivalent
2567 to global on non-NUMA machines)
2568
cbf11071
TM
2569 sunrpc.tcp_slot_table_entries=
2570 sunrpc.udp_slot_table_entries=
2571 [NFS,SUNRPC]
2572 Sets the upper limit on the number of simultaneous
2573 RPC calls that can be sent from the client to a
2574 server. Increasing these values may allow you to
2575 improve throughput, but will also increase the
2576 amount of memory reserved for use by the client.
2577
1da177e4 2578 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 2579
1da177e4
LT
2580 switches= [HW,M68k]
2581
2582 sym53c416= [HW,SCSI]
2583 See header of drivers/scsi/sym53c416.c.
2584
5d6f647f
IM
2585 sysrq_always_enabled
2586 [KNL]
2587 Ignore sysrq setting - this boot parameter will
2588 neutralize any effect of /proc/sys/kernel/sysrq.
2589 Useful for debugging.
2590
1da177e4
LT
2591 t128= [HW,SCSI]
2592 See header of drivers/scsi/t128.c.
2593
2594 tdfx= [HW,DRM]
2595
77437fd4
DB
2596 test_suspend= [SUSPEND]
2597 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2598 standby suspend) as the system sleep state to briefly
2599 enter during system startup. The system is woken from
2600 this state using a wakeup-capable RTC alarm.
2601
1da177e4
LT
2602 thash_entries= [KNL,NET]
2603 Set number of hash buckets for TCP connection
2604
f8707ec9
LB
2605 thermal.act= [HW,ACPI]
2606 -1: disable all active trip points in all thermal zones
2607 <degrees C>: override all lowest active trip points
2608
c52a7419
LB
2609 thermal.crt= [HW,ACPI]
2610 -1: disable all critical trip points in all thermal zones
22a94d79 2611 <degrees C>: override all critical trip points
c52a7419 2612
f5487145
LB
2613 thermal.nocrt= [HW,ACPI]
2614 Set to disable actions on ACPI thermal zone
2615 critical and hot trip points.
2616
72b33ef8
LB
2617 thermal.off= [HW,ACPI]
2618 1: disable ACPI thermal control
2619
a70cdc52
LB
2620 thermal.psv= [HW,ACPI]
2621 -1: disable all passive trip points
ada9cfdd
RD
2622 <degrees C>: override all passive trip points to this
2623 value
a70cdc52 2624
730ff34d
LB
2625 thermal.tzp= [HW,ACPI]
2626 Specify global default ACPI thermal zone polling rate
2627 <deci-seconds>: poll all this frequency
2628 0: no polling (default)
2629
1da177e4
LT
2630 tmscsim= [HW,SCSI]
2631 See comment before function dc390_setup() in
2632 drivers/scsi/tmscsim.c.
2633
2b1a61f0
HC
2634 topology= [S390]
2635 Format: {off | on}
2636 Specify if the kernel should make use of the cpu
2637 topology informations if the hardware supports these.
2638 The scheduler will make use of these informations and
2639 e.g. base its process migration decisions on it.
2640 Default is off.
2641
1da177e4
LT
2642 tp720= [HW,PS2]
2643
225a9be2
RA
2644 tpm_suspend_pcr=[HW,TPM]
2645 Format: integer pcr id
2646 Specify that at suspend time, the tpm driver
2647 should extend the specified pcr with zeros,
2648 as a workaround for some chips which fail to
2649 flush the last written pcr on TPM_SaveState.
2650 This will guarantee that all the other pcrs
2651 are saved.
2652
9d612bef
LZ
2653 trace_buf_size=nn[KMG]
2654 [FTRACE] will set tracing buffer size.
631595fb 2655
020e5f85
LZ
2656 trace_event=[event-list]
2657 [FTRACE] Set and start specified trace events in order
2658 to facilitate early boot debugging.
2659 See also Documentation/trace/events.txt
2660
1da177e4 2661 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
2662 Format:
2663 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2664
395628ef
AK
2665 tsc= Disable clocksource-must-verify flag for TSC.
2666 Format: <string>
2667 [x86] reliable: mark tsc clocksource as reliable, this
2668 disables clocksource verification at runtime.
2669 Used to enable high-resolution timer mode on older
2670 hardware, and in virtualized environment.
2671
a9913044
RD
2672 turbografx.map[2|3]= [HW,JOY]
2673 TurboGraFX parallel port interface
2674 Format:
2675 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
2676 See also Documentation/input/joystick-parport.txt
2677
2678 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2679 See header of drivers/scsi/u14-34f.c.
2680
2681 uart401= [HW,OSS]
2682 Format: <io>,<irq>
2683
2684 uart6850= [HW,OSS]
2685 Format: <io>,<irq>
2686
f86dcc5a
ED
2687 uhash_entries= [KNL,NET]
2688 Set number of hash buckets for UDP/UDP-Lite connections
2689
5f8364b7
AS
2690 uhci-hcd.ignore_oc=
2691 [USB] Ignore overcurrent events (default N).
2692 Some badly-designed motherboards generate lots of
2693 bogus events, for ports that aren't wired to
2694 anything. Set this parameter to avoid log spamming.
2695 Note that genuine overcurrent events won't be
2696 reported either.
2697
e3a61b0a 2698 unknown_nmi_panic
6cececfc 2699 [X86]
e3a61b0a
SA
2700 Set unknown_nmi_panic=1 early on boot.
2701
b5e795f8
AS
2702 usbcore.autosuspend=
2703 [USB] The autosuspend time delay (in seconds) used
2704 for newly-detected USB devices (default 2). This
2705 is the time required before an idle device will be
2706 autosuspended. Devices for which the delay is set
eaafbc3a 2707 to a negative value won't be autosuspended at all.
b5e795f8 2708
fd7c519d
JK
2709 usbcore.usbfs_snoop=
2710 [USB] Set to log all usbfs traffic (default 0 = off).
2711
2712 usbcore.blinkenlights=
2713 [USB] Set to cycle leds on hubs (default 0 = off).
2714
2715 usbcore.old_scheme_first=
2716 [USB] Start with the old device initialization
2717 scheme (default 0 = off).
2718
2719 usbcore.use_both_schemes=
2720 [USB] Try the other device initialization scheme
2721 if the first one fails (default 1 = enabled).
2722
2723 usbcore.initial_descriptor_timeout=
2724 [USB] Specifies timeout for the initial 64-byte
2725 USB_REQ_GET_DESCRIPTOR request in milliseconds
2726 (default 5000 = 5.0 seconds).
2727
1da177e4
LT
2728 usbhid.mousepoll=
2729 [USBHID] The interval which mice are to be polled at.
a9913044 2730
d4f373e5
AS
2731 usb-storage.delay_use=
2732 [UMS] The delay in seconds before a new device is
2733 scanned for Logical Units (default 5).
2734
2735 usb-storage.quirks=
2736 [UMS] A list of quirks entries to supplement or
2737 override the built-in unusual_devs list. List
2738 entries are separated by commas. Each entry has
2739 the form VID:PID:Flags where VID and PID are Vendor
2740 and Product ID values (4-digit hex numbers) and
2741 Flags is a set of characters, each corresponding
2742 to a common usb-storage quirk flag as follows:
c838ea46
AS
2743 a = SANE_SENSE (collect more than 18 bytes
2744 of sense data);
a0bb1081
AS
2745 b = BAD_SENSE (don't collect more than 18
2746 bytes of sense data);
d4f373e5
AS
2747 c = FIX_CAPACITY (decrease the reported
2748 device capacity by one sector);
c838ea46
AS
2749 h = CAPACITY_HEURISTICS (decrease the
2750 reported device capacity by one
2751 sector if the number is odd);
d4f373e5
AS
2752 i = IGNORE_DEVICE (don't bind to this
2753 device);
2754 l = NOT_LOCKABLE (don't try to lock and
2755 unlock ejectable media);
2756 m = MAX_SECTORS_64 (don't transfer more
2757 than 64 sectors = 32 KB at a time);
c838ea46
AS
2758 o = CAPACITY_OK (accept the capacity
2759 reported by the device);
d4f373e5
AS
2760 r = IGNORE_RESIDUE (the device reports
2761 bogus residue values);
2762 s = SINGLE_LUN (the device has only one
2763 Logical Unit);
2764 w = NO_WP_DETECT (don't test whether the
2765 medium is write-protected).
2766 Example: quirks=0419:aaf5:rl,0421:0433:rc
2767
14315592
IC
2768 userpte=
2769 [X86] Flags controlling user PTE allocations.
2770
2771 nohigh = do not allocate PTE pages in
2772 HIGHMEM regardless of setting
2773 of CONFIG_HIGHPTE.
2774
6cececfc 2775 vdso= [X86,SH]
1dbf527c 2776 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
e6e5494c
IM
2777 vdso=1: enable VDSO (default)
2778 vdso=0: disable VDSO mapping
2779
6cececfc 2780 vdso32= [X86]
af65d648
RM
2781 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2782 vdso32=1: enable 32-bit VDSO (default)
2783 vdso32=0: disable 32-bit VDSO mapping
2784
d080d397
YI
2785 vector= [IA-64,SMP]
2786 vector=percpu: enable percpu vector domain
2787
1da177e4
LT
2788 video= [FB] Frame buffer configuration
2789 See Documentation/fb/modedb.txt.
2790
cd4f0ef7 2791 vga= [BOOT,X86-32] Select a particular video mode
954a8b81 2792 See Documentation/x86/boot.txt and
a9913044 2793 Documentation/svga.txt.
1da177e4
LT
2794 Use vga=ask for menu.
2795 This is actually a boot loader parameter; the value is
2796 passed to the kernel using a special protocol.
2797
a9913044 2798 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
2799 size of <nn>. This can be used to increase the
2800 minimum size (128MB on x86). It can also be used to
2801 decrease the size and leave more room for directly
2802 mapped kernel RAM.
2803
585c3047
PO
2804 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2805 Format: <command>
1da177e4 2806
585c3047
PO
2807 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2808 Format: <command>
2809
2810 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2811 Format: <command>
a9913044 2812
9ea9a886
CL
2813 vt.cur_default= [VT] Default cursor shape.
2814 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2815 the parameters of the <Esc>[?A;B;Cc escape sequence;
2816 see VGA-softcursor.txt. Default: 2 = underline.
2817
0cb55ad2
RD
2818 vt.default_blu= [VT]
2819 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2820 Change the default blue palette of the console.
2821 This is a 16-member array composed of values
2822 ranging from 0-255.
2823
2824 vt.default_grn= [VT]
2825 Format: <green0>,<green1>,<green2>,...,<green15>
2826 Change the default green palette of the console.
2827 This is a 16-member array composed of values
2828 ranging from 0-255.
2829
2830 vt.default_red= [VT]
2831 Format: <red0>,<red1>,<red2>,...,<red15>
2832 Change the default red palette of the console.
2833 This is a 16-member array composed of values
2834 ranging from 0-255.
2835
2836 vt.default_utf8=
2837 [VT]
2838 Format=<0|1>
2839 Set system-wide default UTF-8 mode for all tty's.
2840 Default is 1, i.e. UTF-8 mode is enabled for all
2841 newly opened terminals.
2842
f6c06b68
MG
2843 vt.global_cursor_default=
2844 [VT]
2845 Format=<-1|0|1>
2846 Set system-wide default for whether a cursor
2847 is shown on new VTs. Default is -1,
2848 i.e. cursors will be created by default unless
2849 overridden by individual drivers. 0 will hide
2850 cursors, 1 will display them.
2851
1da177e4
LT
2852 waveartist= [HW,OSS]
2853 Format: <io>,<irq>,<dma>,<dma2>
a9913044 2854
1da177e4
LT
2855 wd33c93= [HW,SCSI]
2856 See header of drivers/scsi/wd33c93.c.
2857
2858 wd7000= [HW,SCSI]
2859 See header of drivers/scsi/wd7000.c.
2860
2861 wdt= [WDT] Watchdog
8dfe9c21 2862 See Documentation/watchdog/wdt.txt.
1da177e4 2863
0cb55ad2
RD
2864 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2865 default x2apic cluster mode on platforms
2866 supporting x2apic.
2867
bb24c471
JP
2868 x86_mrst_timer= [X86-32,APBT]
2869 Choose timer option for x86 Moorestown MID platform.
2870 Two valid options are apbt timer only and lapic timer
2871 plus one apbt timer for broadcast timer.
2872 x86_mrst_timer=apbt_only | lapic_and_apbt
2873
1da177e4
LT
2874 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2875 xd_geo= See header of drivers/block/xd.c.
2876
2877 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
2878 Format:
2879 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 2880
a9913044 2881______________________________________________________________________
1da177e4
LT
2882
2883TODO:
2884
2885 Add documentation for ALSA options.
2886 Add more DRM drivers.