| blob | 4d175c7512464671e14731239d5bf943b72c5614 |
1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
4 The 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
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AX25 Appropriate AX.25 support is enabled.
38 DRM Direct Rendering Management support is enabled.
39 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-64 IA-64 architecture is enabled.
45 IOSCHED More than one I/O scheduler is enabled.
46 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
47 ISAPNP ISA PnP code is enabled.
48 ISDN Appropriate ISDN support is enabled.
49 JOY Appropriate joystick support is enabled.
50 LIBATA Libata driver is enabled
51 LP Printer support is enabled.
52 LOOP Loopback device support is enabled.
53 M68k M68k architecture is enabled.
54 These options have more detailed description inside of
55 Documentation/m68k/kernel-options.txt.
56 MCA MCA bus support is enabled.
57 MDA MDA console support is enabled.
58 MOUSE Appropriate mouse support is enabled.
59 MSI Message Signaled Interrupts (PCI).
60 MTD MTD (Memory Technology Device) support is enabled.
61 NET Appropriate network support is enabled.
62 NUMA NUMA support is enabled.
63 GENERIC_TIME The generic timeofday code is enabled.
64 NFS Appropriate NFS support is enabled.
65 OSS OSS sound support is enabled.
66 PV_OPS A paravirtualized kernel is enabled.
67 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
68 PARISC The PA-RISC architecture is enabled.
69 PCI PCI bus support is enabled.
70 PCMCIA The PCMCIA subsystem is enabled.
71 PNP Plug & Play support is enabled.
72 PPC PowerPC architecture is enabled.
73 PPT Parallel port support is enabled.
74 PS2 Appropriate PS/2 support is enabled.
75 RAM RAM disk support is enabled.
76 S390 S390 architecture is enabled.
77 SCSI Appropriate SCSI support is enabled.
78 A lot of drivers has their options described inside of
79 Documentation/scsi/.
80 SELINUX SELinux support is enabled.
81 SERIAL Serial support is enabled.
82 SH SuperH architecture is enabled.
83 SMP The kernel is an SMP kernel.
84 SPARC Sparc architecture is enabled.
85 SWSUSP Software suspend is enabled.
86 TS Appropriate touchscreen support is enabled.
87 USB USB support is enabled.
88 USBHID USB Human Interface Device support is enabled.
89 V4L Video For Linux support is enabled.
90 VGA The VGA console has been enabled.
91 VT Virtual terminal support is enabled.
92 WDT Watchdog support is enabled.
93 XT IBM PC/XT MFM hard disk support is enabled.
94 X86-32 X86-32, aka i386 architecture is enabled.
95 X86-64 X86-64 architecture is enabled.
96 More X86-64 boot options can be found in
97 Documentation/x86_64/boot-options.txt .
99 In addition, the following text indicates that the option:
101 BUGS= Relates to possible processor bugs on the said processor.
102 KNL Is a kernel start-up parameter.
103 BOOT Is a boot loader parameter.
105 Parameters denoted with BOOT are actually interpreted by the boot
106 loader, and have no meaning to the kernel directly.
107 Do not modify the syntax of boot loader parameters without extreme
108 need or coordination with <Documentation/i386/boot.txt>.
110 There are also arch-specific kernel-parameters not documented here.
111 See for example <Documentation/x86_64/boot-options.txt>.
113 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
114 a trailing = on the name of any parameter states that that parameter will
115 be entered as an environment variable, whereas its absence indicates that
116 it will appear as a kernel argument readable via /proc/cmdline by programs
117 running once the system is up.
119 The number of kernel parameters is not limited, but the length of the
120 complete command line (parameters including spaces etc.) is limited to
121 a fixed number of characters. This limit depends on the architecture
122 and is between 256 and 4096 characters. It is defined in the file
123 ./include/asm/setup.h as COMMAND_LINE_SIZE.
126 acpi= [HW,ACPI,X86-64,i386]
127 Advanced Configuration and Power Interface
128 Format: { force | off | ht | strict | noirq }
129 force -- enable ACPI if default was off
130 off -- disable ACPI if default was on
131 noirq -- do not use ACPI for IRQ routing
132 ht -- run only enough ACPI to enable Hyper Threading
133 strict -- Be less tolerant of platforms that are not
134 strictly ACPI specification compliant.
136 See also Documentation/pm.txt, pci=noacpi
138 acpi_apic_instance= [ACPI, IOAPIC]
139 Format: <int>
140 2: use 2nd APIC table, if available
141 1,0: use 1st APIC table
142 default: 0
144 acpi_sleep= [HW,ACPI] Sleep options
145 Format: { s3_bios, s3_mode }
146 See Documentation/power/video.txt
148 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
149 Format: { level | edge | high | low }
151 acpi_irq_balance [HW,ACPI]
152 ACPI will balance active IRQs
153 default in APIC mode
155 acpi_irq_nobalance [HW,ACPI]
156 ACPI will not move active IRQs (default)
157 default in PIC mode
159 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
160 use by PCI
161 Format: <irq>,<irq>...
163 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
164 Format: <irq>,<irq>...
166 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
168 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
169 Format: To spoof as Windows 98: ="Microsoft Windows"
171 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
172 acpi_osi="string1" # add string1 -- only one string
173 acpi_osi="!string2" # remove built-in string2
174 acpi_osi= # disable all strings
176 acpi_serialize [HW,ACPI] force serialization of AML methods
178 acpi_skip_timer_override [HW,ACPI]
179 Recognize and ignore IRQ0/pin2 Interrupt Override.
180 For broken nForce2 BIOS resulting in XT-PIC timer.
181 acpi_use_timer_override [HW,ACPI}
182 Use timer override. For some broken Nvidia NF5 boards
183 that require a timer override, but don't have
184 HPET
186 acpi.debug_layer= [HW,ACPI]
187 Format: <int>
188 Each bit of the <int> indicates an ACPI debug layer,
189 1: enable, 0: disable. It is useful for boot time
190 debugging. After system has booted up, it can be set
191 via /sys/module/acpi/parameters/debug_layer.
192 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
193 Available bits (add the numbers together) to enable debug output
194 for specific parts of the ACPI subsystem:
195 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
196 0x10 namespace 0x20 parser 0x40 dispatcher
197 0x80 executer 0x100 resources 0x200 acpica debugger
198 0x400 os services 0x800 acpica disassembler.
199 The number can be in decimal or prefixed with 0x in hex.
200 Warning: Many of these options can produce a lot of
201 output and make your system unusable. Be very careful.
203 acpi.debug_level= [HW,ACPI]
204 Format: <int>
205 Each bit of the <int> indicates an ACPI debug level,
206 1: enable, 0: disable. It is useful for boot time
207 debugging. After system has booted up, it can be set
208 via /sys/module/acpi/parameters/debug_level.
209 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
210 Available bits (add the numbers together) to enable different
211 debug output levels of the ACPI subsystem:
212 0x01 error 0x02 warn 0x04 init 0x08 debug object
213 0x10 info 0x20 init names 0x40 parse 0x80 load
214 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
215 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
216 0x10000 resources 0x20000 user requests 0x40000 package.
217 The number can be in decimal or prefixed with 0x in hex.
218 Warning: Many of these options can produce a lot of
219 output and make your system unusable. Be very careful.
222 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
224 acpi_pm_good [X86-32,X86-64]
225 Override the pmtimer bug detection: force the kernel
226 to assume that this machine's pmtimer latches its value
227 and always returns good values.
229 agp= [AGP]
230 { off | try_unsupported }
231 off: disable AGP support
232 try_unsupported: try to drive unsupported chipsets
233 (may crash computer or cause data corruption)
235 enable_timer_pin_1 [i386,x86-64]
236 Enable PIN 1 of APIC timer
237 Can be useful to work around chipset bugs
238 (in particular on some ATI chipsets).
239 The kernel tries to set a reasonable default.
241 disable_timer_pin_1 [i386,x86-64]
242 Disable PIN 1 of APIC timer
243 Can be useful to work around chipset bugs.
245 ad1848= [HW,OSS]
246 Format: <io>,<irq>,<dma>,<dma2>,<type>
248 advansys= [HW,SCSI]
249 See header of drivers/scsi/advansys.c.
251 advwdt= [HW,WDT] Advantech WDT
252 Format: <iostart>,<iostop>
254 aedsp16= [HW,OSS] Audio Excel DSP 16
255 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
256 See also header of sound/oss/aedsp16.c.
258 aha152x= [HW,SCSI]
259 See Documentation/scsi/aha152x.txt.
261 aha1542= [HW,SCSI]
262 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
264 aic7xxx= [HW,SCSI]
265 See Documentation/scsi/aic7xxx.txt.
267 aic79xx= [HW,SCSI]
268 See Documentation/scsi/aic79xx.txt.
270 amijoy.map= [HW,JOY] Amiga joystick support
271 Map of devices attached to JOY0DAT and JOY1DAT
272 Format: <a>,<b>
273 See also Documentation/kernel/input/joystick.txt
275 analog.map= [HW,JOY] Analog joystick and gamepad support
276 Specifies type or capabilities of an analog joystick
277 connected to one of 16 gameports
278 Format: <type1>,<type2>,..<type16>
280 apc= [HW,SPARC]
281 Power management functions (SPARCstation-4/5 + deriv.)
282 Format: noidle
283 Disable APC CPU standby support. SPARCstation-Fox does
284 not play well with APC CPU idle - disable it if you have
285 APC and your system crashes randomly.
287 apic= [APIC,i386] Advanced Programmable Interrupt Controller
288 Change the output verbosity whilst booting
289 Format: { quiet (default) | verbose | debug }
290 Change the amount of debugging information output
291 when initialising the APIC and IO-APIC components.
293 apm= [APM] Advanced Power Management
294 See header of arch/i386/kernel/apm.c.
296 applicom= [HW]
297 Format: <mem>,<irq>
299 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
300 Format: <io>,<irq>,<nodeID>
302 ataflop= [HW,M68k]
304 atarimouse= [HW,MOUSE] Atari Mouse
306 atascsi= [HW,SCSI] Atari SCSI
308 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
309 EzKey and similar keyboards
311 atkbd.reset= [HW] Reset keyboard during initialization
313 atkbd.set= [HW] Select keyboard code set
314 Format: <int> (2 = AT (default), 3 = PS/2)
316 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
317 keyboards
319 atkbd.softraw= [HW] Choose between synthetic and real raw mode
320 Format: <bool> (0 = real, 1 = synthetic (default))
322 atkbd.softrepeat= [HW]
323 Use software keyboard repeat
325 autotest [IA64]
327 baycom_epp= [HW,AX25]
328 Format: <io>,<mode>
330 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
331 Format: <io>,<mode>
332 See header of drivers/net/hamradio/baycom_par.c.
334 baycom_ser_fdx= [HW,AX25]
335 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
336 Format: <io>,<irq>,<mode>[,<baud>]
337 See header of drivers/net/hamradio/baycom_ser_fdx.c.
339 baycom_ser_hdx= [HW,AX25]
340 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
341 Format: <io>,<irq>,<mode>
342 See header of drivers/net/hamradio/baycom_ser_hdx.c.
344 blkmtd_device= [HW,MTD]
345 blkmtd_erasesz=
346 blkmtd_ro=
347 blkmtd_bs=
348 blkmtd_count=
350 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
351 bttv.radio= Most important insmod options are available as
352 kernel args too.
353 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
354 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
356 BusLogic= [HW,SCSI]
357 See drivers/scsi/BusLogic.c, comment before function
358 BusLogic_ParseDriverOptions().
360 c101= [NET] Moxa C101 synchronous serial card
362 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
363 Sometimes CPU hardware bugs make them report the cache
364 size incorrectly. The kernel will attempt work arounds
365 to fix known problems, but for some CPUs it is not
366 possible to determine what the correct size should be.
367 This option provides an override for these situations.
369 chandev= [HW,NET] Generic channel device initialisation
371 checkreqprot [SELINUX] Set initial checkreqprot flag value.
372 Format: { "0" | "1" }
373 See security/selinux/Kconfig help text.
374 0 -- check protection applied by kernel (includes
375 any implied execute protection).
376 1 -- check protection requested by application.
377 Default value is set via a kernel config option.
378 Value can be changed at runtime via
379 /selinux/checkreqprot.
381 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
382 [Deprecated]
383 Forces specified clocksource (if available) to be used
384 when calculating gettimeofday(). If specified
385 clocksource is not available, it defaults to PIT.
386 Format: { pit | tsc | cyclone | pmtmr }
388 clocksource= [GENERIC_TIME] Override the default clocksource
389 Format: <string>
390 Override the default clocksource and use the clocksource
391 with the name specified.
392 Some clocksource names to choose from, depending on
393 the platform:
394 [all] jiffies (this is the base, fallback clocksource)
395 [ACPI] acpi_pm
396 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
397 pxa_timer,timer3,32k_counter,timer0_1
398 [AVR32] avr32
399 [X86-32] pit,hpet,tsc,vmi-timer;
400 scx200_hrt on Geode; cyclone on IBM x440
401 [MIPS] MIPS
402 [PARISC] cr16
403 [S390] tod
404 [SH] SuperH
405 [SPARC64] tick
406 [X86-64] hpet,tsc
408 code_bytes [IA32] How many bytes of object code to print in an
409 oops report.
410 Range: 0 - 8192
411 Default: 64
413 disable_8254_timer
414 enable_8254_timer
415 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
416 over the 8254 in addition to over the IO-APIC. The
417 kernel tries to set a sensible default.
419 hpet= [X86-32,HPET] option to disable HPET and use PIT.
420 Format: disable
422 com20020= [HW,NET] ARCnet - COM20020 chipset
423 Format:
424 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
426 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
427 Format: <io>[,<irq>]
429 com90xx= [HW,NET]
430 ARCnet - COM90xx chipset (memory-mapped buffers)
431 Format: <io>[,<irq>[,<memstart>]]
433 condev= [HW,S390] console device
434 conmode=
436 console= [KNL] Output console device and options.
438 tty<n> Use the virtual console device <n>.
440 ttyS<n>[,options]
441 ttyUSB0[,options]
442 Use the specified serial port. The options are of
443 the form "bbbbpnf", where "bbbb" is the baud rate,
444 "p" is parity ("n", "o", or "e"), "n" is number of
445 bits, and "f" is flow control ("r" for RTS or
446 omit it). Default is "9600n8".
448 See Documentation/serial-console.txt for more
449 information. See
450 Documentation/networking/netconsole.txt for an
451 alternative.
453 uart[8250],io,<addr>[,options]
454 uart[8250],mmio,<addr>[,options]
455 Start an early, polled-mode console on the 8250/16550
456 UART at the specified I/O port or MMIO address,
457 switching to the matching ttyS device later. The
458 options are the same as for ttyS, above.
460 earlycon= [KNL] Output early console device and options.
461 uart[8250],io,<addr>[,options]
462 uart[8250],mmio,<addr>[,options]
463 Start an early, polled-mode console on the 8250/16550
464 UART at the specified I/O port or MMIO address.
465 The options are the same as for ttyS, above.
467 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
468 Format:
469 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
471 crashkernel=nn[KMG]@ss[KMG]
472 [KNL] Reserve a chunk of physical memory to
473 hold a kernel to switch to with kexec on panic.
475 cs4232= [HW,OSS]
476 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
478 cs89x0_dma= [HW,NET]
479 Format: <dma>
481 cs89x0_media= [HW,NET]
482 Format: { rj45 | aui | bnc }
484 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
486 dasd= [HW,NET]
487 See header of drivers/s390/block/dasd_devmap.c.
489 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
490 (one device per port)
491 Format: <port#>,<type>
492 See also Documentation/input/joystick-parport.txt
494 debug [KNL] Enable kernel debugging (events log level).
496 debug_locks_verbose=
497 [KNL] verbose self-tests
498 Format=<0|1>
499 Print debugging info while doing the locking API
500 self-tests.
501 We default to 0 (no extra messages), setting it to
502 1 will print _a lot_ more information - normally
503 only useful to kernel developers.
505 decnet= [HW,NET]
506 Format: <area>[,<node>]
507 See also Documentation/networking/decnet.txt.
509 default_blu= [VT]
510 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
511 Change the default blue palette of the console.
512 This is a 16-member array composed of values
513 ranging from 0-255.
515 default_grn= [VT]
516 Format: <green0>,<green1>,<green2>,...,<green15>
517 Change the default green palette of the console.
518 This is a 16-member array composed of values
519 ranging from 0-255.
521 default_red= [VT]
522 Format: <red0>,<red1>,<red2>,...,<red15>
523 Change the default red palette of the console.
524 This is a 16-member array composed of values
525 ranging from 0-255.
527 default_utf8= [VT]
528 Format=<0|1>
529 Set system-wide default UTF-8 mode for all tty's.
530 Default is 0 and by setting to 1, it enables UTF-8
531 mode for all newly opened or allocated terminals.
533 dhash_entries= [KNL]
534 Set number of hash buckets for dentry cache.
536 digi= [HW,SERIAL]
537 IO parameters + enable/disable command.
539 digiepca= [HW,SERIAL]
540 See drivers/char/README.epca and
541 Documentation/digiepca.txt.
543 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
544 support available.
545 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
547 dmasound= [HW,OSS] Sound subsystem buffers
549 dscc4.setup= [NET]
551 dtc3181e= [HW,SCSI]
553 earlyprintk= [X86-32,X86-64,SH]
554 earlyprintk=vga
555 earlyprintk=serial[,ttySn[,baudrate]]
557 Append ",keep" to not disable it when the real console
558 takes over.
560 Only vga or serial at a time, not both.
562 Currently only ttyS0 and ttyS1 are supported.
564 Interaction with the standard serial driver is not
565 very good.
567 The VGA output is eventually overwritten by the real
568 console.
570 eata= [HW,SCSI]
572 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
573 Format: <int>
574 0: polling mode
575 non-0: interrupt mode (default)
577 eda= [HW,PS2]
579 edb= [HW,PS2]
581 edd= [EDD]
582 Format: {"of[f]" | "sk[ipmbr]"}
583 See comment in arch/i386/boot/edd.S
585 eicon= [HW,ISDN]
586 Format: <id>,<membase>,<irq>
588 eisa_irq_edge= [PARISC,HW]
589 See header of drivers/parisc/eisa.c.
591 elanfreq= [X86-32]
592 See comment before function elanfreq_setup() in
593 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
595 elevator= [IOSCHED]
596 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
597 See Documentation/block/as-iosched.txt and
598 Documentation/block/deadline-iosched.txt for details.
600 elfcorehdr= [X86-32, X86_64]
601 Specifies physical address of start of kernel core
602 image elf header. Generally kexec loader will
603 pass this option to capture kernel.
604 See Documentation/kdump/kdump.txt for details.
606 enforcing [SELINUX] Set initial enforcing status.
607 Format: {"0" | "1"}
608 See security/selinux/Kconfig help text.
609 0 -- permissive (log only, no denials).
610 1 -- enforcing (deny and log).
611 Default value is 0.
612 Value can be changed at runtime via /selinux/enforce.
614 es1371= [HW,OSS]
615 Format: <spdif>,[<nomix>,[<amplifier>]]
616 See also header of sound/oss/es1371.c.
618 ether= [HW,NET] Ethernet cards parameters
619 This option is obsoleted by the "netdev=" option, which
620 has equivalent usage. See its documentation for details.
622 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
623 Format: <io>[,<irq>]
625 failslab=
626 fail_page_alloc=
627 fail_make_request=[KNL]
628 General fault injection mechanism.
629 Format: <interval>,<probability>,<space>,<times>
630 See also /Documentation/fault-injection/.
632 fd_mcs= [HW,SCSI]
633 See header of drivers/scsi/fd_mcs.c.
635 fdomain= [HW,SCSI]
636 See header of drivers/scsi/fdomain.c.
638 floppy= [HW]
639 See Documentation/floppy.txt.
641 gamecon.map[2|3]=
642 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
643 support via parallel port (up to 5 devices per port)
644 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
645 See also Documentation/input/joystick-parport.txt
647 gamma= [HW,DRM]
649 gdth= [HW,SCSI]
650 See header of drivers/scsi/gdth.c.
652 gpt [EFI] Forces disk with valid GPT signature but
653 invalid Protective MBR to be treated as GPT.
655 gvp11= [HW,SCSI]
657 hashdist= [KNL,NUMA] Large hashes allocated during boot
658 are distributed across NUMA nodes. Defaults on
659 for IA-64, off otherwise.
660 Format: 0 | 1 (for off | on)
662 hcl= [IA-64] SGI's Hardware Graph compatibility layer
664 hd= [EIDE] (E)IDE hard drive subsystem geometry
665 Format: <cyl>,<head>,<sect>
667 hd?= [HW] (E)IDE subsystem
668 hd?lun= See Documentation/ide.txt.
670 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
671 size of <nn>. This works even on boxes that have no
672 highmem otherwise. This also works to reduce highmem
673 size on bigger boxes.
675 highres= [KNL] Enable/disable high resolution timer mode.
676 Valid parameters: "on", "off"
677 Default: "on"
679 hisax= [HW,ISDN]
680 See Documentation/isdn/README.HiSax.
682 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
684 i8042.direct [HW] Put keyboard port into non-translated mode
685 i8042.dumbkbd [HW] Pretend that controller can only read data from
686 keyboard and cannot control its state
687 (Don't attempt to blink the leds)
688 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
689 i8042.nokbd [HW] Don't check/create keyboard port
690 i8042.nomux [HW] Don't check presence of an active multiplexing
691 controller
692 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
693 controllers
694 i8042.panicblink=
695 [HW] Frequency with which keyboard LEDs should blink
696 when kernel panics (default is 0.5 sec)
697 i8042.reset [HW] Reset the controller during init and cleanup
698 i8042.unlock [HW] Unlock (ignore) the keylock
700 i810= [HW,DRM]
702 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
703 indicates that the driver is running on unsupported
704 hardware.
705 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
706 does not match list of supported models.
707 i8k.power_status
708 [HW] Report power status in /proc/i8k
709 (disabled by default)
710 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
711 capability is set.
713 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
714 See Documentation/mca.txt.
716 icn= [HW,ISDN]
717 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
719 ide= [HW] (E)IDE subsystem
720 Format: ide=nodma or ide=doubler or ide=reverse
721 See Documentation/ide.txt.
723 ide?= [HW] (E)IDE subsystem
724 Format: ide?=noprobe or chipset specific parameters.
725 See Documentation/ide.txt.
727 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
728 See Documentation/ide.txt.
730 idle= [X86]
731 Format: idle=poll or idle=mwait
732 Poll forces a polling idle loop that can slightly improves the performance
733 of waking up a idle CPU, but will use a lot of power and make the system
734 run hot. Not recommended.
735 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
736 to not use it because it doesn't save as much power as a normal idle
737 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
738 as idle=poll.
740 ignore_loglevel [KNL]
741 Ignore loglevel setting - this will print /all/
742 kernel messages to the console. Useful for debugging.
744 ihash_entries= [KNL]
745 Set number of hash buckets for inode cache.
747 in2000= [HW,SCSI]
748 See header of drivers/scsi/in2000.c.
750 init= [KNL]
751 Format: <full_path>
752 Run specified binary instead of /sbin/init as init
753 process.
755 initcall_debug [KNL] Trace initcalls as they are executed. Useful
756 for working out where the kernel is dying during
757 startup.
759 initrd= [BOOT] Specify the location of the initial ramdisk
761 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
762 Format: <irq>
764 inttest= [IA64]
766 io7= [HW] IO7 for Marvel based alpha systems
767 See comment before marvel_specify_io7 in
768 arch/alpha/kernel/core_marvel.c.
770 ip= [IP_PNP]
771 See Documentation/nfsroot.txt.
773 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
774 See comment before ip2_setup() in
775 drivers/char/ip2/ip2base.c.
777 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
778 See header of drivers/scsi/ips.c.
780 ports= [IP_VS_FTP] IPVS ftp helper module
781 Default is 21.
782 Up to 8 (IP_VS_APP_MAX_PORTS) ports
783 may be specified.
784 Format: <port>,<port>....
786 irqfixup [HW]
787 When an interrupt is not handled search all handlers
788 for it. Intended to get systems with badly broken
789 firmware running.
791 irqpoll [HW]
792 When an interrupt is not handled search all handlers
793 for it. Also check all handlers each timer
794 interrupt. Intended to get systems with badly broken
795 firmware running.
797 isapnp= [ISAPNP]
798 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
800 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
801 Format:
802 <cpu number>,...,<cpu number>
803 or
804 <cpu number>-<cpu number> (must be a positive range in ascending order)
805 or a mixture
806 <cpu number>,...,<cpu number>-<cpu number>
807 This option can be used to specify one or more CPUs
808 to isolate from the general SMP balancing and scheduling
809 algorithms. The only way to move a process onto or off
810 an "isolated" CPU is via the CPU affinity syscalls.
811 <cpu number> begins at 0 and the maximum value is
812 "number of CPUs in system - 1".
814 This option is the preferred way to isolate CPUs. The
815 alternative -- manually setting the CPU mask of all
816 tasks in the system -- can cause problems and
817 suboptimal load balancer performance.
819 iucv= [HW,NET]
821 js= [HW,JOY] Analog joystick
822 See Documentation/input/joystick.txt.
824 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
825 specifies the amount of memory usable by the kernel
826 for non-movable allocations. The requested amount is
827 spread evenly throughout all nodes in the system. The
828 remaining memory in each node is used for Movable
829 pages. In the event, a node is too small to have both
830 kernelcore and Movable pages, kernelcore pages will
831 take priority and other nodes will have a larger number
832 of kernelcore pages. The Movable zone is used for the
833 allocation of pages that may be reclaimed or moved
834 by the page migration subsystem. This means that
835 HugeTLB pages may not be allocated from this zone.
836 Note that allocations like PTEs-from-HighMem still
837 use the HighMem zone if it exists, and the Normal
838 zone if it does not.
840 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
841 is similar to kernelcore except it specifies the
842 amount of memory used for migratable allocations.
843 If both kernelcore and movablecore is specified,
844 then kernelcore will be at *least* the specified
845 value but may be more. If movablecore on its own
846 is specified, the administrator must be careful
847 that the amount of memory usable for all allocations
848 is not too small.
850 keepinitrd [HW,ARM]
852 kstack=N [X86-32,X86-64] Print N words from the kernel stack
853 in oops dumps.
855 l2cr= [PPC]
857 lapic [X86-32,APIC] Enable the local APIC even if BIOS
858 disabled it.
860 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
861 C2 power state.
863 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
864 Format: addr:<io>,irq:<irq>
866 load_ramdisk= [RAM] List of ramdisks to load from floppy
867 See Documentation/ramdisk.txt.
869 lockd.nlm_grace_period=P [NFS] Assign grace period.
870 Format: <integer>
872 lockd.nlm_tcpport=N [NFS] Assign TCP port.
873 Format: <integer>
875 lockd.nlm_timeout=T [NFS] Assign timeout value.
876 Format: <integer>
878 lockd.nlm_udpport=M [NFS] Assign UDP port.
879 Format: <integer>
881 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
882 Format: <irq>
884 loglevel= All Kernel Messages with a loglevel smaller than the
885 console loglevel will be printed to the console. It can
886 also be changed with klogd or other programs. The
887 loglevels are defined as follows:
889 0 (KERN_EMERG) system is unusable
890 1 (KERN_ALERT) action must be taken immediately
891 2 (KERN_CRIT) critical conditions
892 3 (KERN_ERR) error conditions
893 4 (KERN_WARNING) warning conditions
894 5 (KERN_NOTICE) normal but significant condition
895 6 (KERN_INFO) informational
896 7 (KERN_DEBUG) debug-level messages
898 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
899 Format: { n | nk | nM }
900 n must be a power of two. The default size
901 is set in the kernel config file.
903 lp=0 [LP] Specify parallel ports to use, e.g,
904 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
905 lp=reset first parallel port). 'lp=0' disables the
906 lp=auto printer driver. 'lp=reset' (which can be
907 specified in addition to the ports) causes
908 attached printers to be reset. Using
909 lp=port1,port2,... specifies the parallel ports
910 to associate lp devices with, starting with
911 lp0. A port specification may be 'none' to skip
912 that lp device, or a parport name such as
913 'parport0'. Specifying 'lp=auto' instead of a
914 port specification list means that device IDs
915 from each port should be examined, to see if
916 an IEEE 1284-compliant printer is attached; if
917 so, the driver will manage that printer.
918 See also header of drivers/char/lp.c.
920 lpj=n [KNL]
921 Sets loops_per_jiffy to given constant, thus avoiding
922 time-consuming boot-time autodetection (up to 250 ms per
923 CPU). 0 enables autodetection (default). To determine
924 the correct value for your kernel, boot with normal
925 autodetection and see what value is printed. Note that
926 on SMP systems the preset will be applied to all CPUs,
927 which is likely to cause problems if your CPUs need
928 significantly divergent settings. An incorrect value
929 will cause delays in the kernel to be wrong, leading to
930 unpredictable I/O errors and other breakage. Although
931 unlikely, in the extreme case this might damage your
932 hardware.
934 ltpc= [NET]
935 Format: <io>,<irq>,<dma>
937 mac5380= [HW,SCSI] Format:
938 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
940 mac53c9x= [HW,SCSI] Format:
941 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
943 machvec= [IA64] Force the use of a particular machine-vector
944 (machvec) in a generic kernel.
945 Example: machvec=hpzx1_swiotlb
947 max_loop= [LOOP] Maximum number of loopback devices that can
948 be mounted
949 Format: <1-256>
951 maxcpus= [SMP] Maximum number of processors that an SMP kernel
952 should make use of. maxcpus=n : n >= 0 limits the
953 kernel to using 'n' processors. n=0 is a special case,
954 it is equivalent to "nosmp", which also disables
955 the IO APIC.
957 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
958 equal to this physical address is ignored.
960 max_luns= [SCSI] Maximum number of LUNs to probe.
961 Should be between 1 and 2^32-1.
963 max_report_luns=
964 [SCSI] Maximum number of LUNs received.
965 Should be between 1 and 16384.
967 mca-pentium [BUGS=X86-32]
969 mcatest= [IA-64]
971 mce [X86-32] Machine Check Exception
973 md= [HW] RAID subsystems devices and level
974 See Documentation/md.txt.
976 mdacon= [MDA]
977 Format: <first>,<last>
978 Specifies range of consoles to be captured by the MDA.
980 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
981 Amount of memory to be used when the kernel is not able
982 to see the whole system memory or for test.
983 [X86-32] Use together with memmap= to avoid physical
984 address space collisions. Without memmap= PCI devices
985 could be placed at addresses belonging to unused RAM.
987 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
988 memory.
990 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
991 E820 memory map, as specified by the user.
992 Such memmap=exactmap lines can be constructed based on
993 BIOS output or other requirements. See the memmap=nn@ss
994 option description.
996 memmap=nn[KMG]@ss[KMG]
997 [KNL] Force usage of a specific region of memory
998 Region of memory to be used, from ss to ss+nn.
1000 memmap=nn[KMG]#ss[KMG]
1001 [KNL,ACPI] Mark specific memory as ACPI data.
1002 Region of memory to be used, from ss to ss+nn.
1004 memmap=nn[KMG]$ss[KMG]
1005 [KNL,ACPI] Mark specific memory as reserved.
1006 Region of memory to be used, from ss to ss+nn.
1008 meye.*= [HW] Set MotionEye Camera parameters
1009 See Documentation/video4linux/meye.txt.
1011 mga= [HW,DRM]
1013 mousedev.tap_time=
1014 [MOUSE] Maximum time between finger touching and
1015 leaving touchpad surface for touch to be considered
1016 a tap and be reported as a left button click (for
1017 touchpads working in absolute mode only).
1018 Format: <msecs>
1019 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1020 reporting absolute coordinates, such as tablets
1021 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1022 reporting absolute coordinates, such as tablets
1024 mpu401= [HW,OSS]
1025 Format: <io>,<irq>
1027 MTD_Partition= [MTD]
1028 Format: <name>,<region-number>,<size>,<offset>
1030 MTD_Region= [MTD] Format:
1031 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1033 mtdparts= [MTD]
1034 See drivers/mtd/cmdlinepart.c.
1036 mtouchusb.raw_coordinates=
1037 [HW] Make the MicroTouch USB driver use raw coordinates
1038 ('y', default) or cooked coordinates ('n')
1040 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1042 NCR_D700= [HW,SCSI]
1043 See header of drivers/scsi/NCR_D700.c.
1045 ncr5380= [HW,SCSI]
1047 ncr53c400= [HW,SCSI]
1049 ncr53c400a= [HW,SCSI]
1051 ncr53c406a= [HW,SCSI]
1053 ncr53c8xx= [HW,SCSI]
1055 netdev= [NET] Network devices parameters
1056 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1057 Note that mem_start is often overloaded to mean
1058 something different and driver-specific.
1059 This usage is only documented in each driver source
1060 file if at all.
1062 nfsaddrs= [NFS]
1063 See Documentation/nfsroot.txt.
1065 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1066 See Documentation/nfsroot.txt.
1068 nfs.callback_tcpport=
1069 [NFS] set the TCP port on which the NFSv4 callback
1070 channel should listen.
1072 nfs.idmap_cache_timeout=
1073 [NFS] set the maximum lifetime for idmapper cache
1074 entries.
1076 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1078 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1079 emulation library even if a 387 maths coprocessor
1080 is present.
1082 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1083 when set.
1084 Format: <int>
1086 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1087 caches in the slab allocator. Saves per-node memory,
1088 but will impact performance.
1090 noalign [KNL,ARM]
1092 noapic [SMP,APIC] Tells the kernel to not make use of any
1093 IOAPICs that may be present in the system.
1095 noasync [HW,M68K] Disables async and sync negotiation for
1096 all devices.
1098 nobats [PPC] Do not use BATs for mapping kernel lowmem
1099 on "Classic" PPC cores.
1101 nocache [ARM]
1103 nodelayacct [KNL] Disable per-task delay accounting
1105 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1107 noexec [IA-64]
1109 noexec [X86-32,X86-64]
1110 noexec=on: enable non-executable mappings (default)
1111 noexec=off: disable nn-executable mappings
1113 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1114 register save and restore. The kernel will only save
1115 legacy floating-point registers on task switch.
1117 nohlt [BUGS=ARM]
1119 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1120 instruction doesn't work correctly and not to
1121 use it.
1123 nohalt [IA-64] Tells the kernel not to use the power saving
1124 function PAL_HALT_LIGHT when idle. This increases
1125 power-consumption. On the positive side, it reduces
1126 interrupt wake-up latency, which may improve performance
1127 in certain environments such as networked servers or
1128 real-time systems.
1130 nohz= [KNL] Boottime enable/disable dynamic ticks
1131 Valid arguments: on, off
1132 Default: on
1134 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1136 noirqdebug [X86-32] Disables the code which attempts to detect and
1137 disable unhandled interrupt sources.
1139 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1140 broken timer IRQ sources.
1142 noisapnp [ISAPNP] Disables ISA PnP code.
1144 noinitrd [RAM] Tells the kernel not to load any configured
1145 initial RAM disk.
1147 nointroute [IA-64]
1149 nojitter [IA64] Disables jitter checking for ITC timers.
1151 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1153 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1155 noltlbs [PPC] Do not use large page/tlb entries for kernel
1156 lowmem mapping on PPC40x.
1158 nomca [IA-64] Disable machine check abort handling
1160 nomce [X86-32] Machine Check Exception
1162 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1164 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1165 with UP alternatives
1167 noresidual [PPC] Don't use residual data on PReP machines.
1169 noresume [SWSUSP] Disables resume and restores original swap
1170 space.
1172 no-scroll [VGA] Disables scrollback.
1173 This is required for the Braillex ib80-piezo Braille
1174 reader made by F.H. Papenmeier (Germany).
1176 nosbagart [IA-64]
1178 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1180 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1181 and disable the IO APIC. legacy for "maxcpus=0".
1183 nosoftlockup [KNL] Disable the soft-lockup detector.
1185 nosync [HW,M68K] Disables sync negotiation for all devices.
1187 notsc [BUGS=X86-32] Disable Time Stamp Counter
1189 nousb [USB] Disable the USB subsystem
1191 nowb [ARM]
1193 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1194 one of ['zone', 'node', 'default'] can be specified
1195 This can be set from sysctl after boot.
1196 See Documentation/sysctl/vm.txt for details.
1198 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1200 opl3= [HW,OSS]
1201 Format: <io>
1203 oprofile.timer= [HW]
1204 Use timer interrupt instead of performance counters
1206 osst= [HW,SCSI] SCSI Tape Driver
1207 Format: <buffer_size>,<write_threshold>
1208 See also Documentation/scsi/st.txt.
1210 panic= [KNL] Kernel behaviour on panic
1211 Format: <timeout>
1213 parkbd.port= [HW] Parallel port number the keyboard adapter is
1214 connected to, default is 0.
1215 Format: <parport#>
1216 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1217 0 for XT, 1 for AT (default is AT).
1218 Format: <mode>
1220 parport= [HW,PPT] Specify parallel ports. 0 disables.
1221 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1222 Use 'auto' to force the driver to use any
1223 IRQ/DMA settings detected (the default is to
1224 ignore detected IRQ/DMA settings because of
1225 possible conflicts). You can specify the base
1226 address, IRQ, and DMA settings; IRQ and DMA
1227 should be numbers, or 'auto' (for using detected
1228 settings on that particular port), or 'nofifo'
1229 (to avoid using a FIFO even if it is detected).
1230 Parallel ports are assigned in the order they
1231 are specified on the command line, starting
1232 with parport0.
1234 parport_init_mode= [HW,PPT]
1235 Configure VIA parallel port to operate in
1236 a specific mode. This is necessary on Pegasos
1237 computer where firmware has no options for setting
1238 up parallel port mode and sets it to spp.
1239 Currently this function knows 686a and 8231 chips.
1240 Format: [spp|ps2|epp|ecp|ecpepp]
1242 pas2= [HW,OSS] Format:
1243 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1245 pas16= [HW,SCSI]
1246 See header of drivers/scsi/pas16.c.
1248 pause_on_oops=
1249 Halt all CPUs after the first oops has been printed for
1250 the specified number of seconds. This is to be used if
1251 your oopses keep scrolling off the screen.
1253 pcbit= [HW,ISDN]
1255 pcd. [PARIDE]
1256 See header of drivers/block/paride/pcd.c.
1257 See also Documentation/paride.txt.
1259 pci=option[,option...] [PCI] various PCI subsystem options:
1260 off [X86-32] don't probe for the PCI bus
1261 bios [X86-32] force use of PCI BIOS, don't access
1262 the hardware directly. Use this if your machine
1263 has a non-standard PCI host bridge.
1264 nobios [X86-32] disallow use of PCI BIOS, only direct
1265 hardware access methods are allowed. Use this
1266 if you experience crashes upon bootup and you
1267 suspect they are caused by the BIOS.
1268 conf1 [X86-32] Force use of PCI Configuration
1269 Mechanism 1.
1270 conf2 [X86-32] Force use of PCI Configuration
1271 Mechanism 2.
1272 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1273 Configuration
1274 nomsi [MSI] If the PCI_MSI kernel config parameter is
1275 enabled, this kernel boot option can be used to
1276 disable the use of MSI interrupts system-wide.
1277 nosort [X86-32] Don't sort PCI devices according to
1278 order given by the PCI BIOS. This sorting is
1279 done to get a device order compatible with
1280 older kernels.
1281 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1282 routing table. These calls are known to be buggy
1283 on several machines and they hang the machine
1284 when used, but on other computers it's the only
1285 way to get the interrupt routing table. Try
1286 this option if the kernel is unable to allocate
1287 IRQs or discover secondary PCI buses on your
1288 motherboard.
1289 rom [X86-32] Assign address space to expansion ROMs.
1290 Use with caution as certain devices share
1291 address decoders between ROMs and other
1292 resources.
1293 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1294 assigned automatically to PCI devices. You can
1295 make the kernel exclude IRQs of your ISA cards
1296 this way.
1297 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1298 of the PIRQ table (normally generated
1299 by the BIOS) if it is outside the
1300 F0000h-100000h range.
1301 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1302 useful if the kernel is unable to find your
1303 secondary buses and you want to tell it
1304 explicitly which ones they are.
1305 assign-busses [X86-32] Always assign all PCI bus
1306 numbers ourselves, overriding
1307 whatever the firmware may have done.
1308 usepirqmask [X86-32] Honor the possible IRQ mask stored
1309 in the BIOS $PIR table. This is needed on
1310 some systems with broken BIOSes, notably
1311 some HP Pavilion N5400 and Omnibook XE3
1312 notebooks. This will have no effect if ACPI
1313 IRQ routing is enabled.
1314 noacpi [X86-32] Do not use ACPI for IRQ routing
1315 or for PCI scanning.
1316 routeirq Do IRQ routing for all PCI devices.
1317 This is normally done in pci_enable_device(),
1318 so this option is a temporary workaround
1319 for broken drivers that don't call it.
1320 firmware [ARM] Do not re-enumerate the bus but instead
1321 just use the configuration from the
1322 bootloader. This is currently used on
1323 IXP2000 systems where the bus has to be
1324 configured a certain way for adjunct CPUs.
1325 noearly [X86] Don't do any early type 1 scanning.
1326 This might help on some broken boards which
1327 machine check when some devices' config space
1328 is read. But various workarounds are disabled
1329 and some IOMMU drivers will not work.
1330 bfsort Sort PCI devices into breadth-first order.
1331 This sorting is done to get a device
1332 order compatible with older (<= 2.4) kernels.
1333 nobfsort Don't sort PCI devices into breadth-first order.
1334 cbiosize=nn[KMG] The fixed amount of bus space which is
1335 reserved for the CardBus bridge's IO window.
1336 The default value is 256 bytes.
1337 cbmemsize=nn[KMG] The fixed amount of bus space which is
1338 reserved for the CardBus bridge's memory
1339 window. The default value is 64 megabytes.
1341 pcmv= [HW,PCMCIA] BadgePAD 4
1343 pd. [PARIDE]
1344 See Documentation/paride.txt.
1346 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1347 boot time.
1348 Format: { 0 | 1 }
1349 See arch/parisc/kernel/pdc_chassis.c
1351 pf. [PARIDE]
1352 See Documentation/paride.txt.
1354 pg. [PARIDE]
1355 See Documentation/paride.txt.
1357 pirq= [SMP,APIC] Manual mp-table setup
1358 See Documentation/i386/IO-APIC.txt.
1360 plip= [PPT,NET] Parallel port network link
1361 Format: { parport<nr> | timid | 0 }
1362 See also Documentation/parport.txt.
1364 pnpacpi= [ACPI]
1365 { off }
1367 pnpbios= [ISAPNP]
1368 { on | off | curr | res | no-curr | no-res }
1370 pnp_reserve_irq=
1371 [ISAPNP] Exclude IRQs for the autoconfiguration
1373 pnp_reserve_dma=
1374 [ISAPNP] Exclude DMAs for the autoconfiguration
1376 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1377 Ranges are in pairs (I/O port base and size).
1379 pnp_reserve_mem=
1380 [ISAPNP] Exclude memory regions for the
1381 autoconfiguration.
1382 Ranges are in pairs (memory base and size).
1384 print-fatal-signals=
1385 [KNL] debug: print fatal signals
1386 print-fatal-signals=1: print segfault info to
1387 the kernel console.
1388 default: off.
1390 printk.time= Show timing data prefixed to each printk message line
1391 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1393 profile= [KNL] Enable kernel profiling via /proc/profile
1394 Format: [schedule,]<number>
1395 Param: "schedule" - profile schedule points.
1396 Param: <number> - step/bucket size as a power of 2 for
1397 statistical time based profiling.
1398 Param: "sleep" - profile D-state sleeping (millisecs)
1400 processor.max_cstate= [HW,ACPI]
1401 Limit processor to maximum C-state
1402 max_cstate=9 overrides any DMI blacklist limit.
1404 processor.nocst [HW,ACPI]
1405 Ignore the _CST method to determine C-states,
1406 instead using the legacy FADT method
1408 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1409 before loading.
1410 See Documentation/ramdisk.txt.
1412 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1413 probe for; one of (bare|imps|exps|lifebook|any).
1414 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1415 per second.
1416 psmouse.resetafter= [HW,MOUSE]
1417 Try to reset the device after so many bad packets
1418 (0 = never).
1419 psmouse.resolution=
1420 [HW,MOUSE] Set desired mouse resolution, in dpi.
1421 psmouse.smartscroll=
1422 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1423 0 = disabled, 1 = enabled (default).
1425 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1426 Format:
1427 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1429 pt. [PARIDE]
1430 See Documentation/paride.txt.
1432 quiet [KNL] Disable most log messages
1434 r128= [HW,DRM]
1436 raid= [HW,RAID]
1437 See Documentation/md.txt.
1439 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1440 See Documentation/ramdisk.txt.
1442 ramdisk_blocksize= [RAM]
1443 See Documentation/ramdisk.txt.
1445 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1446 New name for the ramdisk parameter.
1447 See Documentation/ramdisk.txt.
1449 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1450 RCU callbacks to process in one batch.
1452 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1453 RCU callbacks over which batch limiting is disabled.
1455 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1456 RCU callbacks below which batch limiting is re-enabled.
1458 rdinit= [KNL]
1459 Format: <full_path>
1460 Run specified binary instead of /init from the ramdisk,
1461 used for early userspace startup. See initrd.
1463 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1464 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1465 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1467 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1469 reservetop= [X86-32]
1470 Format: nn[KMG]
1471 Reserves a hole at the top of the kernel virtual
1472 address space.
1474 reset_devices [KNL] Force drivers to reset the underlying device
1475 during initialization.
1477 resume= [SWSUSP]
1478 Specify the partition device for software suspend
1480 resume_offset= [SWSUSP]
1481 Specify the offset from the beginning of the partition
1482 given by "resume=" at which the swap header is located,
1483 in <PAGE_SIZE> units (needed only for swap files).
1484 See Documentation/power/swsusp-and-swap-files.txt
1486 retain_initrd [RAM] Keep initrd memory after extraction
1488 rhash_entries= [KNL,NET]
1489 Set number of hash buckets for route cache
1491 riscom8= [HW,SERIAL]
1492 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1494 ro [KNL] Mount root device read-only on boot
1496 root= [KNL] Root filesystem
1498 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1499 mount the root filesystem
1501 rootflags= [KNL] Set root filesystem mount option string
1503 rootfstype= [KNL] Set root filesystem type
1505 rootwait [KNL] Wait (indefinitely) for root device to show up.
1506 Useful for devices that are detected asynchronously
1507 (e.g. USB and MMC devices).
1509 rw [KNL] Mount root device read-write on boot
1511 S [KNL] Run init in single mode
1513 sa1100ir [NET]
1514 See drivers/net/irda/sa1100_ir.c.
1516 sb= [HW,OSS]
1517 Format: <io>,<irq>,<dma>,<dma2>
1519 sbni= [NET] Granch SBNI12 leased line adapter
1521 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1522 Format: <io>[,<timeout>[,<isapnp>]]
1524 scsi_debug_*= [SCSI]
1525 See drivers/scsi/scsi_debug.c.
1527 scsi_default_dev_flags=
1528 [SCSI] SCSI default device flags
1529 Format: <integer>
1531 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1532 Format: <vendor>:<model>:<flags>
1533 (flags are integer value)
1535 scsi_logging= [SCSI]
1537 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1538 discovered. async scans them in kernel threads,
1539 allowing boot to proceed. none ignores them, expecting
1540 user space to do the scan.
1542 selinux [SELINUX] Disable or enable SELinux at boot time.
1543 Format: { "0" | "1" }
1544 See security/selinux/Kconfig help text.
1545 0 -- disable.
1546 1 -- enable.
1547 Default value is set via kernel config option.
1548 If enabled at boot time, /selinux/disable can be used
1549 later to disable prior to initial policy load.
1551 selinux_compat_net =
1552 [SELINUX] Set initial selinux_compat_net flag value.
1553 Format: { "0" | "1" }
1554 0 -- use new secmark-based packet controls
1555 1 -- use legacy packet controls
1556 Default value is 0 (preferred).
1557 Value can be changed at runtime via
1558 /selinux/compat_net.
1560 serialnumber [BUGS=X86-32]
1562 sg_def_reserved_size= [SCSI]
1564 shapers= [NET]
1565 Maximal number of shapers.
1567 sim710= [SCSI,HW]
1568 See header of drivers/scsi/sim710.c.
1570 simeth= [IA-64]
1571 simscsi=
1573 slram= [HW,MTD]
1575 slub_debug[=options[,slabs]] [MM, SLUB]
1576 Enabling slub_debug allows one to determine the
1577 culprit if slab objects become corrupted. Enabling
1578 slub_debug can create guard zones around objects and
1579 may poison objects when not in use. Also tracks the
1580 last alloc / free. For more information see
1581 Documentation/vm/slub.txt.
1583 slub_max_order= [MM, SLUB]
1584 Determines the maximum allowed order for slabs.
1585 A high setting may cause OOMs due to memory
1586 fragmentation. For more information see
1587 Documentation/vm/slub.txt.
1589 slub_min_objects= [MM, SLUB]
1590 The minimum number of objects per slab. SLUB will
1591 increase the slab order up to slub_max_order to
1592 generate a sufficiently large slab able to contain
1593 the number of objects indicated. The higher the number
1594 of objects the smaller the overhead of tracking slabs
1595 and the less frequently locks need to be acquired.
1596 For more information see Documentation/vm/slub.txt.
1598 slub_min_order= [MM, SLUB]
1599 Determines the mininum page order for slabs. Must be
1600 lower than slub_max_order.
1601 For more information see Documentation/vm/slub.txt.
1603 slub_nomerge [MM, SLUB]
1604 Disable merging of slabs with similar size. May be
1605 necessary if there is some reason to distinguish
1606 allocs to different slabs. Debug options disable
1607 merging on their own.
1608 For more information see Documentation/vm/slub.txt.
1610 smart2= [HW]
1611 Format: <io1>[,<io2>[,...,<io8>]]
1613 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1614 attempt to substitute SMP alternatives once at boot.
1616 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1617 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1618 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1619 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1620 smsc-ircc2.ircc_irq= [HW] IRQ line
1621 smsc-ircc2.ircc_dma= [HW] DMA channel
1622 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1623 0: Toshiba Satellite 1800 (GP data pin select)
1624 1: Fast pin select (default)
1625 2: ATC IRMode
1627 snd-ad1816a= [HW,ALSA]
1629 snd-ad1848= [HW,ALSA]
1631 snd-ali5451= [HW,ALSA]
1633 snd-als100= [HW,ALSA]
1635 snd-als4000= [HW,ALSA]
1637 snd-azt2320= [HW,ALSA]
1639 snd-cmi8330= [HW,ALSA]
1641 snd-cmipci= [HW,ALSA]
1643 snd-cs4231= [HW,ALSA]
1645 snd-cs4232= [HW,ALSA]
1647 snd-cs4236= [HW,ALSA]
1649 snd-cs4281= [HW,ALSA]
1651 snd-cs46xx= [HW,ALSA]
1653 snd-dt019x= [HW,ALSA]
1655 snd-dummy= [HW,ALSA]
1657 snd-emu10k1= [HW,ALSA]
1659 snd-ens1370= [HW,ALSA]
1661 snd-ens1371= [HW,ALSA]
1663 snd-es968= [HW,ALSA]
1665 snd-es1688= [HW,ALSA]
1667 snd-es18xx= [HW,ALSA]
1669 snd-es1938= [HW,ALSA]
1671 snd-es1968= [HW,ALSA]
1673 snd-fm801= [HW,ALSA]
1675 snd-gusclassic= [HW,ALSA]
1677 snd-gusextreme= [HW,ALSA]
1679 snd-gusmax= [HW,ALSA]
1681 snd-hdsp= [HW,ALSA]
1683 snd-ice1712= [HW,ALSA]
1685 snd-intel8x0= [HW,ALSA]
1687 snd-interwave= [HW,ALSA]
1689 snd-interwave-stb=
1690 [HW,ALSA]
1692 snd-korg1212= [HW,ALSA]
1694 snd-maestro3= [HW,ALSA]
1696 snd-mpu401= [HW,ALSA]
1698 snd-mtpav= [HW,ALSA]
1700 snd-nm256= [HW,ALSA]
1702 snd-opl3sa2= [HW,ALSA]
1704 snd-opti92x-ad1848=
1705 [HW,ALSA]
1707 snd-opti92x-cs4231=
1708 [HW,ALSA]
1710 snd-opti93x= [HW,ALSA]
1712 snd-pmac= [HW,ALSA]
1714 snd-rme32= [HW,ALSA]
1716 snd-rme96= [HW,ALSA]
1718 snd-rme9652= [HW,ALSA]
1720 snd-sb8= [HW,ALSA]
1722 snd-sb16= [HW,ALSA]
1724 snd-sbawe= [HW,ALSA]
1726 snd-serial= [HW,ALSA]
1728 snd-sgalaxy= [HW,ALSA]
1730 snd-sonicvibes= [HW,ALSA]
1732 snd-sun-amd7930=
1733 [HW,ALSA]
1735 snd-sun-cs4231= [HW,ALSA]
1737 snd-trident= [HW,ALSA]
1739 snd-usb-audio= [HW,ALSA,USB]
1741 snd-via82xx= [HW,ALSA]
1743 snd-virmidi= [HW,ALSA]
1745 snd-wavefront= [HW,ALSA]
1747 snd-ymfpci= [HW,ALSA]
1749 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1750 See Documentation/sonypi.txt
1752 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1753 See Documentation/specialix.txt.
1755 spia_io_base= [HW,MTD]
1756 spia_fio_base=
1757 spia_pedr=
1758 spia_peddr=
1760 sscape= [HW,OSS]
1761 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1763 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1764 See Documentation/scsi/st.txt.
1766 st0x= [HW,SCSI]
1767 See header of drivers/scsi/seagate.c.
1769 sti= [PARISC,HW]
1770 Format: <num>
1771 Set the STI (builtin display/keyboard on the HP-PARISC
1772 machines) console (graphic card) which should be used
1773 as the initial boot-console.
1774 See also comment in drivers/video/console/sticore.c.
1776 sti_font= [HW]
1777 See comment in drivers/video/console/sticore.c.
1779 stifb= [HW]
1780 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1782 sunrpc.pool_mode=
1783 [NFS]
1784 Control how the NFS server code allocates CPUs to
1785 service thread pools. Depending on how many NICs
1786 you have and where their interrupts are bound, this
1787 option will affect which CPUs will do NFS serving.
1788 Note: this parameter cannot be changed while the
1789 NFS server is running.
1791 auto the server chooses an appropriate mode
1792 automatically using heuristics
1793 global a single global pool contains all CPUs
1794 percpu one pool for each CPU
1795 pernode one pool for each NUMA node (equivalent
1796 to global on non-NUMA machines)
1798 swiotlb= [IA-64] Number of I/O TLB slabs
1800 switches= [HW,M68k]
1802 sym53c416= [HW,SCSI]
1803 See header of drivers/scsi/sym53c416.c.
1805 sysrq_always_enabled
1806 [KNL]
1807 Ignore sysrq setting - this boot parameter will
1808 neutralize any effect of /proc/sys/kernel/sysrq.
1809 Useful for debugging.
1811 t128= [HW,SCSI]
1812 See header of drivers/scsi/t128.c.
1814 tdfx= [HW,DRM]
1816 thash_entries= [KNL,NET]
1817 Set number of hash buckets for TCP connection
1819 thermal.act= [HW,ACPI]
1820 -1: disable all active trip points in all thermal zones
1821 <degrees C>: override all lowest active trip points
1823 thermal.crt= [HW,ACPI]
1824 -1: disable all critical trip points in all thermal zones
1825 <degrees C>: lower all critical trip points
1827 thermal.nocrt= [HW,ACPI]
1828 Set to disable actions on ACPI thermal zone
1829 critical and hot trip points.
1831 thermal.off= [HW,ACPI]
1832 1: disable ACPI thermal control
1834 thermal.psv= [HW,ACPI]
1835 -1: disable all passive trip points
1836 <degrees C>: override all passive trip points to this value
1838 thermal.tzp= [HW,ACPI]
1839 Specify global default ACPI thermal zone polling rate
1840 <deci-seconds>: poll all this frequency
1841 0: no polling (default)
1843 time Show timing data prefixed to each printk message line
1844 [deprecated, see 'printk.time']
1846 tipar.timeout= [HW,PPT]
1847 Set communications timeout in tenths of a second
1848 (default 15).
1850 tipar.delay= [HW,PPT]
1851 Set inter-bit delay in microseconds (default 10).
1853 tmc8xx= [HW,SCSI]
1854 See header of drivers/scsi/seagate.c.
1856 tmscsim= [HW,SCSI]
1857 See comment before function dc390_setup() in
1858 drivers/scsi/tmscsim.c.
1860 tp720= [HW,PS2]
1862 trix= [HW,OSS] MediaTrix AudioTrix Pro
1863 Format:
1864 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1866 tsdev.xres= [TS] Horizontal screen resolution.
1867 tsdev.yres= [TS] Vertical screen resolution.
1869 turbografx.map[2|3]= [HW,JOY]
1870 TurboGraFX parallel port interface
1871 Format:
1872 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1873 See also Documentation/input/joystick-parport.txt
1875 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1876 See header of drivers/scsi/u14-34f.c.
1878 uart401= [HW,OSS]
1879 Format: <io>,<irq>
1881 uart6850= [HW,OSS]
1882 Format: <io>,<irq>
1884 uhci-hcd.ignore_oc=
1885 [USB] Ignore overcurrent events (default N).
1886 Some badly-designed motherboards generate lots of
1887 bogus events, for ports that aren't wired to
1888 anything. Set this parameter to avoid log spamming.
1889 Note that genuine overcurrent events won't be
1890 reported either.
1892 usbcore.autosuspend=
1893 [USB] The autosuspend time delay (in seconds) used
1894 for newly-detected USB devices (default 2). This
1895 is the time required before an idle device will be
1896 autosuspended. Devices for which the delay is set
1897 to a negative value won't be autosuspended at all.
1899 usbhid.mousepoll=
1900 [USBHID] The interval which mice are to be polled at.
1902 vdso= [X86-32,SH,x86-64]
1903 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1904 vdso=1: enable VDSO (default)
1905 vdso=0: disable VDSO mapping
1907 vector= [IA-64,SMP]
1908 vector=percpu: enable percpu vector domain
1910 video= [FB] Frame buffer configuration
1911 See Documentation/fb/modedb.txt.
1913 vga= [BOOT,X86-32] Select a particular video mode
1914 See Documentation/i386/boot.txt and
1915 Documentation/svga.txt.
1916 Use vga=ask for menu.
1917 This is actually a boot loader parameter; the value is
1918 passed to the kernel using a special protocol.
1920 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1921 size of <nn>. This can be used to increase the
1922 minimum size (128MB on x86). It can also be used to
1923 decrease the size and leave more room for directly
1924 mapped kernel RAM.
1926 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1927 Format: <command>
1929 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1930 Format: <command>
1932 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1933 Format: <command>
1935 waveartist= [HW,OSS]
1936 Format: <io>,<irq>,<dma>,<dma2>
1938 wd33c93= [HW,SCSI]
1939 See header of drivers/scsi/wd33c93.c.
1941 wd7000= [HW,SCSI]
1942 See header of drivers/scsi/wd7000.c.
1944 wdt= [WDT] Watchdog
1945 See Documentation/watchdog/wdt.txt.
1947 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1948 xd_geo= See header of drivers/block/xd.c.
1950 xirc2ps_cs= [NET,PCMCIA]
1951 Format:
1952 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1954 norandmaps Don't use address space randomization
1955 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1957 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1958 This is useful to get more information why
1959 you got a "dwarf2 unwinder stuck"
1961 ______________________________________________________________________
1963 TODO:
1965 Add documentation for ALSA options.
1966 Add more DRM drivers.