| blob | 026e4e5d9b231bfce86253d8748918c76ae47223 |
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 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD 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-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LIBATA Libata driver is enabled
52 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
60 MSI Message Signaled Interrupts (PCI).
61 MTD MTD support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
64 GENERIC_TIME The generic timeofday code is enabled.
65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PV_OPS A paravirtualized kernel
68 PARIDE The ParIDE subsystem is enabled.
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCMCIA The PCMCIA subsystem is enabled.
72 PNP Plug & Play support is enabled.
73 PPC PowerPC architecture is enabled.
74 PPT Parallel port support is enabled.
75 PS2 Appropriate PS/2 support is enabled.
76 RAM RAM disk support is enabled.
77 S390 S390 architecture is enabled.
78 SCSI Appropriate SCSI support is enabled.
79 A lot of drivers has their options described inside of
80 Documentation/scsi/.
81 SELINUX SELinux support is enabled.
82 SERIAL Serial support is enabled.
83 SH SuperH architecture is enabled.
84 SMP The kernel is an SMP kernel.
85 SPARC Sparc architecture is enabled.
86 SWSUSP Software suspend is enabled.
87 TS Appropriate touchscreen support is enabled.
88 USB USB support is enabled.
89 USBHID USB Human Interface Device support is enabled.
90 V4L Video For Linux support is enabled.
91 VGA The VGA console has been enabled.
92 VT Virtual terminal support is enabled.
93 WDT Watchdog support is enabled.
94 XT IBM PC/XT MFM hard disk support 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 53c7xx= [HW,SCSI] Amiga SCSI controllers
127 See header of drivers/scsi/53c7xx.c.
128 See also Documentation/scsi/ncr53c7xx.txt.
130 acpi= [HW,ACPI,X86-64,i386]
131 Advanced Configuration and Power Interface
132 Format: { force | off | ht | strict | noirq }
133 force -- enable ACPI if default was off
134 off -- disable ACPI if default was on
135 noirq -- do not use ACPI for IRQ routing
136 ht -- run only enough ACPI to enable Hyper Threading
137 strict -- Be less tolerant of platforms that are not
138 strictly ACPI specification compliant.
140 See also Documentation/pm.txt, pci=noacpi
142 acpi_apic_instance= [ACPI, IOAPIC]
143 Format: <int>
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
146 default: 0
148 acpi_sleep= [HW,ACPI] Sleep options
149 Format: { s3_bios, s3_mode }
150 See Documentation/power/video.txt
152 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
153 Format: { level | edge | high | low }
155 acpi_irq_balance [HW,ACPI]
156 ACPI will balance active IRQs
157 default in APIC mode
159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
161 default in PIC mode
163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
164 use by PCI
165 Format: <irq>,<irq>...
167 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
168 Format: <irq>,<irq>...
170 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
171 Format: To spoof as Windows 98: ="Microsoft Windows"
173 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
174 acpi_osi="string1" # add string1 -- only one string
175 acpi_osi="!string2" # remove built-in string2
176 acpi_osi= # disable all strings
178 acpi_serialize [HW,ACPI] force serialization of AML methods
180 acpi_skip_timer_override [HW,ACPI]
181 Recognize and ignore IRQ0/pin2 Interrupt Override.
182 For broken nForce2 BIOS resulting in XT-PIC timer.
183 acpi_use_timer_override [HW,ACPI}
184 Use timer override. For some broken Nvidia NF5 boards
185 that require a timer override, but don't have
186 HPET
188 acpi.debug_layer= [HW,ACPI]
189 Format: <int>
190 Each bit of the <int> indicates an ACPI debug layer,
191 1: enable, 0: disable. It is useful for boot time
192 debugging. After system has booted up, it can be set
193 via /sys/module/acpi/parameters/debug_layer.
194 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
195 Available bits (add the numbers together) to enable debug output
196 for specific parts of the ACPI subsystem:
197 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
198 0x10 namespace 0x20 parser 0x40 dispatcher
199 0x80 executer 0x100 resources 0x200 acpica debugger
200 0x400 os services 0x800 acpica disassembler.
201 The number can be in decimal or prefixed with 0x in hex.
202 Warning: Many of these options can produce a lot of
203 output and make your system unusable. Be very careful.
205 acpi.debug_level= [HW,ACPI]
206 Format: <int>
207 Each bit of the <int> indicates an ACPI debug level,
208 1: enable, 0: disable. It is useful for boot time
209 debugging. After system has booted up, it can be set
210 via /sys/module/acpi/parameters/debug_level.
211 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
212 Available bits (add the numbers together) to enable different
213 debug output levels of the ACPI subsystem:
214 0x01 error 0x02 warn 0x04 init 0x08 debug object
215 0x10 info 0x20 init names 0x40 parse 0x80 load
216 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
217 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
218 0x10000 resources 0x20000 user requests 0x40000 package.
219 The number can be in decimal or prefixed with 0x in hex.
220 Warning: Many of these options can produce a lot of
221 output and make your system unusable. Be very careful.
224 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
226 acpi_pm_good [IA-32,X86-64]
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
231 enable_timer_pin_1 [i386,x86-64]
232 Enable PIN 1 of APIC timer
233 Can be useful to work around chipset bugs
234 (in particular on some ATI chipsets).
235 The kernel tries to set a reasonable default.
237 disable_timer_pin_1 [i386,x86-64]
238 Disable PIN 1 of APIC timer
239 Can be useful to work around chipset bugs.
241 ad1816= [HW,OSS]
242 Format: <io>,<irq>,<dma>,<dma2>
243 See also Documentation/sound/oss/AD1816.
245 ad1848= [HW,OSS]
246 Format: <io>,<irq>,<dma>,<dma2>,<type>
248 adlib= [HW,OSS]
249 Format: <io>
251 advansys= [HW,SCSI]
252 See header of drivers/scsi/advansys.c.
254 advwdt= [HW,WDT] Advantech WDT
255 Format: <iostart>,<iostop>
257 aedsp16= [HW,OSS] Audio Excel DSP 16
258 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
259 See also header of sound/oss/aedsp16.c.
261 aha152x= [HW,SCSI]
262 See Documentation/scsi/aha152x.txt.
264 aha1542= [HW,SCSI]
265 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
267 aic7xxx= [HW,SCSI]
268 See Documentation/scsi/aic7xxx.txt.
270 aic79xx= [HW,SCSI]
271 See Documentation/scsi/aic79xx.txt.
273 amijoy.map= [HW,JOY] Amiga joystick support
274 Map of devices attached to JOY0DAT and JOY1DAT
275 Format: <a>,<b>
276 See also Documentation/kernel/input/joystick.txt
278 analog.map= [HW,JOY] Analog joystick and gamepad support
279 Specifies type or capabilities of an analog joystick
280 connected to one of 16 gameports
281 Format: <type1>,<type2>,..<type16>
283 apc= [HW,SPARC]
284 Power management functions (SPARCstation-4/5 + deriv.)
285 Format: noidle
286 Disable APC CPU standby support. SPARCstation-Fox does
287 not play well with APC CPU idle - disable it if you have
288 APC and your system crashes randomly.
290 apic= [APIC,i386] Change the output verbosity whilst booting
291 Format: { quiet (default) | verbose | debug }
292 Change the amount of debugging information output
293 when initialising the APIC and IO-APIC components.
295 apm= [APM] Advanced Power Management
296 See header of arch/i386/kernel/apm.c.
298 applicom= [HW]
299 Format: <mem>,<irq>
301 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
302 Format: <io>,<irq>,<nodeID>
304 ataflop= [HW,M68k]
306 atarimouse= [HW,MOUSE] Atari Mouse
308 atascsi= [HW,SCSI] Atari SCSI
310 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
311 EzKey and similar keyboards
313 atkbd.reset= [HW] Reset keyboard during initialization
315 atkbd.set= [HW] Select keyboard code set
316 Format: <int> (2 = AT (default), 3 = PS/2)
318 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
319 keyboards
321 atkbd.softraw= [HW] Choose between synthetic and real raw mode
322 Format: <bool> (0 = real, 1 = synthetic (default))
324 atkbd.softrepeat= [HW]
325 Use software keyboard repeat
327 autotest [IA64]
329 aztcd= [HW,CD] Aztech CD268 CDROM driver
330 Format: <io>,0x79 (?)
332 baycom_epp= [HW,AX25]
333 Format: <io>,<mode>
335 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
336 Format: <io>,<mode>
337 See header of drivers/net/hamradio/baycom_par.c.
339 baycom_ser_fdx= [HW,AX25]
340 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
341 Format: <io>,<irq>,<mode>[,<baud>]
342 See header of drivers/net/hamradio/baycom_ser_fdx.c.
344 baycom_ser_hdx= [HW,AX25]
345 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
346 Format: <io>,<irq>,<mode>
347 See header of drivers/net/hamradio/baycom_ser_hdx.c.
349 blkmtd_device= [HW,MTD]
350 blkmtd_erasesz=
351 blkmtd_ro=
352 blkmtd_bs=
353 blkmtd_count=
355 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
356 bttv.radio= Most important insmod options are available as
357 kernel args too.
358 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
359 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
361 BusLogic= [HW,SCSI]
362 See drivers/scsi/BusLogic.c, comment before function
363 BusLogic_ParseDriverOptions().
365 c101= [NET] Moxa C101 synchronous serial card
367 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
368 Sometimes CPU hardware bugs make them report the cache
369 size incorrectly. The kernel will attempt work arounds
370 to fix known problems, but for some CPUs it is not
371 possible to determine what the correct size should be.
372 This option provides an override for these situations.
374 cdu31a= [HW,CD]
375 Format: <io>,<irq>[,PAS]
376 See header of drivers/cdrom/cdu31a.c.
378 chandev= [HW,NET] Generic channel device initialisation
380 checkreqprot [SELINUX] Set initial checkreqprot flag value.
381 Format: { "0" | "1" }
382 See security/selinux/Kconfig help text.
383 0 -- check protection applied by kernel (includes
384 any implied execute protection).
385 1 -- check protection requested by application.
386 Default value is set via a kernel config option.
387 Value can be changed at runtime via
388 /selinux/checkreqprot.
390 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
391 [Deprecated]
392 Forces specified clocksource (if available) to be used
393 when calculating gettimeofday(). If specified
394 clocksource is not available, it defaults to PIT.
395 Format: { pit | tsc | cyclone | pmtmr }
397 clocksource= [GENERIC_TIME] Override the default clocksource
398 Format: <string>
399 Override the default clocksource and use the clocksource
400 with the name specified.
401 Some clocksource names to choose from, depending on
402 the platform:
403 [all] jiffies (this is the base, fallback clocksource)
404 [ACPI] acpi_pm
405 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
406 pxa_timer,timer3,32k_counter,timer0_1
407 [AVR32] avr32
408 [IA-32] pit,hpet,tsc,vmi-timer;
409 scx200_hrt on Geode; cyclone on IBM x440
410 [MIPS] MIPS
411 [PARISC] cr16
412 [S390] tod
413 [SH] SuperH
414 [SPARC64] tick
415 [X86-64] hpet,tsc
417 code_bytes [IA32] How many bytes of object code to print in an
418 oops report.
419 Range: 0 - 8192
420 Default: 64
422 disable_8254_timer
423 enable_8254_timer
424 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
425 over the 8254 in addition to over the IO-APIC. The
426 kernel tries to set a sensible default.
428 hpet= [IA-32,HPET] option to disable HPET and use PIT.
429 Format: disable
431 cm206= [HW,CD]
432 Format: { auto | [<io>,][<irq>] }
434 com20020= [HW,NET] ARCnet - COM20020 chipset
435 Format:
436 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
438 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
439 Format: <io>[,<irq>]
441 com90xx= [HW,NET]
442 ARCnet - COM90xx chipset (memory-mapped buffers)
443 Format: <io>[,<irq>[,<memstart>]]
445 condev= [HW,S390] console device
446 conmode=
448 console= [KNL] Output console device and options.
450 tty<n> Use the virtual console device <n>.
452 ttyS<n>[,options]
453 ttyUSB0[,options]
454 Use the specified serial port. The options are of
455 the form "bbbbpnf", where "bbbb" is the baud rate,
456 "p" is parity ("n", "o", or "e"), "n" is number of
457 bits, and "f" is flow control ("r" for RTS or
458 omit it). Default is "9600n8".
460 See Documentation/serial-console.txt for more
461 information. See
462 Documentation/networking/netconsole.txt for an
463 alternative.
465 uart,io,<addr>[,options]
466 uart,mmio,<addr>[,options]
467 Start an early, polled-mode console on the 8250/16550
468 UART at the specified I/O port or MMIO address,
469 switching to the matching ttyS device later. The
470 options are the same as for ttyS, above.
472 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
473 Format:
474 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
476 cpia_pp= [HW,PPT]
477 Format: { parport<nr> | auto | none }
479 crashkernel=nn[KMG]@ss[KMG]
480 [KNL] Reserve a chunk of physical memory to
481 hold a kernel to switch to with kexec on panic.
483 cs4232= [HW,OSS]
484 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
486 cs89x0_dma= [HW,NET]
487 Format: <dma>
489 cs89x0_media= [HW,NET]
490 Format: { rj45 | aui | bnc }
492 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
494 dasd= [HW,NET]
495 See header of drivers/s390/block/dasd_devmap.c.
497 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
498 (one device per port)
499 Format: <port#>,<type>
500 See also Documentation/input/joystick-parport.txt
502 debug [KNL] Enable kernel debugging (events log level).
504 debug_locks_verbose=
505 [KNL] verbose self-tests
506 Format=<0|1>
507 Print debugging info while doing the locking API
508 self-tests.
509 We default to 0 (no extra messages), setting it to
510 1 will print _a lot_ more information - normally
511 only useful to kernel developers.
513 decnet= [HW,NET]
514 Format: <area>[,<node>]
515 See also Documentation/networking/decnet.txt.
517 default_blu= [VT]
518 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
519 Change the default blue palette of the console.
520 This is a 16-member array composed of values
521 ranging from 0-255.
523 default_grn= [VT]
524 Format: <green0>,<green1>,<green2>,...,<green15>
525 Change the default green palette of the console.
526 This is a 16-member array composed of values
527 ranging from 0-255.
529 default_red= [VT]
530 Format: <red0>,<red1>,<red2>,...,<red15>
531 Change the default red palette of the console.
532 This is a 16-member array composed of values
533 ranging from 0-255.
535 default_utf8= [VT]
536 Format=<0|1>
537 Set system-wide default UTF-8 mode for all tty's.
538 Default is 0 and by setting to 1, it enables UTF-8
539 mode for all newly opened or allocated terminals.
541 dhash_entries= [KNL]
542 Set number of hash buckets for dentry cache.
544 digi= [HW,SERIAL]
545 IO parameters + enable/disable command.
547 digiepca= [HW,SERIAL]
548 See drivers/char/README.epca and
549 Documentation/digiepca.txt.
551 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
552 support available.
553 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
555 dmasound= [HW,OSS] Sound subsystem buffers
557 dscc4.setup= [NET]
559 dtc3181e= [HW,SCSI]
561 earlyprintk= [IA-32,X86-64,SH]
562 earlyprintk=vga
563 earlyprintk=serial[,ttySn[,baudrate]]
565 Append ",keep" to not disable it when the real console
566 takes over.
568 Only vga or serial at a time, not both.
570 Currently only ttyS0 and ttyS1 are supported.
572 Interaction with the standard serial driver is not
573 very good.
575 The VGA output is eventually overwritten by the real
576 console.
578 eata= [HW,SCSI]
580 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
581 Format: <int>
582 0: polling mode
583 non-0: interrupt mode (default)
585 eda= [HW,PS2]
587 edb= [HW,PS2]
589 edd= [EDD]
590 Format: {"of[f]" | "sk[ipmbr]"}
591 See comment in arch/i386/boot/edd.S
593 eicon= [HW,ISDN]
594 Format: <id>,<membase>,<irq>
596 eisa_irq_edge= [PARISC,HW]
597 See header of drivers/parisc/eisa.c.
599 elanfreq= [IA-32]
600 See comment before function elanfreq_setup() in
601 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
603 elevator= [IOSCHED]
604 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
605 See Documentation/block/as-iosched.txt and
606 Documentation/block/deadline-iosched.txt for details.
608 elfcorehdr= [IA-32, X86_64]
609 Specifies physical address of start of kernel core
610 image elf header. Generally kexec loader will
611 pass this option to capture kernel.
612 See Documentation/kdump/kdump.txt for details.
614 enforcing [SELINUX] Set initial enforcing status.
615 Format: {"0" | "1"}
616 See security/selinux/Kconfig help text.
617 0 -- permissive (log only, no denials).
618 1 -- enforcing (deny and log).
619 Default value is 0.
620 Value can be changed at runtime via /selinux/enforce.
622 es1371= [HW,OSS]
623 Format: <spdif>,[<nomix>,[<amplifier>]]
624 See also header of sound/oss/es1371.c.
626 ether= [HW,NET] Ethernet cards parameters
627 This option is obsoleted by the "netdev=" option, which
628 has equivalent usage. See its documentation for details.
630 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
631 Format: <io>[,<irq>]
633 failslab=
634 fail_page_alloc=
635 fail_make_request=[KNL]
636 General fault injection mechanism.
637 Format: <interval>,<probability>,<space>,<times>
638 See also /Documentation/fault-injection/.
640 fd_mcs= [HW,SCSI]
641 See header of drivers/scsi/fd_mcs.c.
643 fdomain= [HW,SCSI]
644 See header of drivers/scsi/fdomain.c.
646 floppy= [HW]
647 See Documentation/floppy.txt.
649 gamecon.map[2|3]=
650 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
651 support via parallel port (up to 5 devices per port)
652 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
653 See also Documentation/input/joystick-parport.txt
655 gamma= [HW,DRM]
657 gdth= [HW,SCSI]
658 See header of drivers/scsi/gdth.c.
660 gpt [EFI] Forces disk with valid GPT signature but
661 invalid Protective MBR to be treated as GPT.
663 gscd= [HW,CD]
664 Format: <io>
666 gvp11= [HW,SCSI]
668 hashdist= [KNL,NUMA] Large hashes allocated during boot
669 are distributed across NUMA nodes. Defaults on
670 for IA-64, off otherwise.
671 Format: 0 | 1 (for off | on)
673 hcl= [IA-64] SGI's Hardware Graph compatibility layer
675 hd= [EIDE] (E)IDE hard drive subsystem geometry
676 Format: <cyl>,<head>,<sect>
678 hd?= [HW] (E)IDE subsystem
679 hd?lun= See Documentation/ide.txt.
681 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
682 size of <nn>. This works even on boxes that have no
683 highmem otherwise. This also works to reduce highmem
684 size on bigger boxes.
686 highres= [KNL] Enable/disable high resolution timer mode.
687 Valid parameters: "on", "off"
688 Default: "on"
690 hisax= [HW,ISDN]
691 See Documentation/isdn/README.HiSax.
693 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
695 i8042.direct [HW] Put keyboard port into non-translated mode
696 i8042.dumbkbd [HW] Pretend that controller can only read data from
697 keyboard and cannot control its state
698 (Don't attempt to blink the leds)
699 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
700 i8042.nokbd [HW] Don't check/create keyboard port
701 i8042.nomux [HW] Don't check presence of an active multiplexing
702 controller
703 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
704 controllers
705 i8042.panicblink=
706 [HW] Frequency with which keyboard LEDs should blink
707 when kernel panics (default is 0.5 sec)
708 i8042.reset [HW] Reset the controller during init and cleanup
709 i8042.unlock [HW] Unlock (ignore) the keylock
711 i810= [HW,DRM]
713 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
714 indicates that the driver is running on unsupported
715 hardware.
716 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
717 does not match list of supported models.
718 i8k.power_status
719 [HW] Report power status in /proc/i8k
720 (disabled by default)
721 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
722 capability is set.
724 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
725 See Documentation/mca.txt.
727 icn= [HW,ISDN]
728 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
730 ide= [HW] (E)IDE subsystem
731 Format: ide=nodma or ide=doubler or ide=reverse
732 See Documentation/ide.txt.
734 ide?= [HW] (E)IDE subsystem
735 Format: ide?=noprobe or chipset specific parameters.
736 See Documentation/ide.txt.
738 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
739 See Documentation/ide.txt.
741 idle= [X86]
742 Format: idle=poll or idle=mwait
743 Poll forces a polling idle loop that can slightly improves the performance
744 of waking up a idle CPU, but will use a lot of power and make the system
745 run hot. Not recommended.
746 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
747 to not use it because it doesn't save as much power as a normal idle
748 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
749 as idle=poll.
751 ignore_loglevel [KNL]
752 Ignore loglevel setting - this will print /all/
753 kernel messages to the console. Useful for debugging.
755 ihash_entries= [KNL]
756 Set number of hash buckets for inode cache.
758 in2000= [HW,SCSI]
759 See header of drivers/scsi/in2000.c.
761 init= [KNL]
762 Format: <full_path>
763 Run specified binary instead of /sbin/init as init
764 process.
766 initcall_debug [KNL] Trace initcalls as they are executed. Useful
767 for working out where the kernel is dying during
768 startup.
770 initrd= [BOOT] Specify the location of the initial ramdisk
772 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
773 Format: <irq>
775 inttest= [IA64]
777 io7= [HW] IO7 for Marvel based alpha systems
778 See comment before marvel_specify_io7 in
779 arch/alpha/kernel/core_marvel.c.
781 ip= [IP_PNP]
782 See Documentation/nfsroot.txt.
784 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
785 See comment before ip2_setup() in drivers/char/ip2.c.
787 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
788 See header of drivers/scsi/ips.c.
790 ports= [IP_VS_FTP] IPVS ftp helper module
791 Default is 21.
792 Up to 8 (IP_VS_APP_MAX_PORTS) ports
793 may be specified.
794 Format: <port>,<port>....
796 irqfixup [HW]
797 When an interrupt is not handled search all handlers
798 for it. Intended to get systems with badly broken
799 firmware running.
801 irqpoll [HW]
802 When an interrupt is not handled search all handlers
803 for it. Also check all handlers each timer
804 interrupt. Intended to get systems with badly broken
805 firmware running.
807 isapnp= [ISAPNP]
808 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
810 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
811 Format:
812 <cpu number>,...,<cpu number>
813 or
814 <cpu number>-<cpu number> (must be a positive range in ascending order)
815 or a mixture
816 <cpu number>,...,<cpu number>-<cpu number>
817 This option can be used to specify one or more CPUs
818 to isolate from the general SMP balancing and scheduling
819 algorithms. The only way to move a process onto or off
820 an "isolated" CPU is via the CPU affinity syscalls.
821 <cpu number> begins at 0 and the maximum value is
822 "number of CPUs in system - 1".
824 This option is the preferred way to isolate CPUs. The
825 alternative -- manually setting the CPU mask of all
826 tasks in the system -- can cause problems and
827 suboptimal load balancer performance.
829 isp16= [HW,CD]
830 Format: <io>,<irq>,<dma>,<setup>
832 iucv= [HW,NET]
834 js= [HW,JOY] Analog joystick
835 See Documentation/input/joystick.txt.
837 keepinitrd [HW,ARM]
839 kstack=N [IA-32,X86-64] Print N words from the kernel stack
840 in oops dumps.
842 l2cr= [PPC]
844 lapic [IA-32,APIC] Enable the local APIC even if BIOS
845 disabled it.
847 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
848 C2 power state.
850 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
851 Format: addr:<io>,irq:<irq>
853 llsc*= [IA64] See function print_params() in
854 arch/ia64/sn/kernel/llsc4.c.
856 load_ramdisk= [RAM] List of ramdisks to load from floppy
857 See Documentation/ramdisk.txt.
859 lockd.nlm_grace_period=P [NFS] Assign grace period.
860 Format: <integer>
862 lockd.nlm_tcpport=N [NFS] Assign TCP port.
863 Format: <integer>
865 lockd.nlm_timeout=T [NFS] Assign timeout value.
866 Format: <integer>
868 lockd.nlm_udpport=M [NFS] Assign UDP port.
869 Format: <integer>
871 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
872 Format: <irq>
874 loglevel= All Kernel Messages with a loglevel smaller than the
875 console loglevel will be printed to the console. It can
876 also be changed with klogd or other programs. The
877 loglevels are defined as follows:
879 0 (KERN_EMERG) system is unusable
880 1 (KERN_ALERT) action must be taken immediately
881 2 (KERN_CRIT) critical conditions
882 3 (KERN_ERR) error conditions
883 4 (KERN_WARNING) warning conditions
884 5 (KERN_NOTICE) normal but significant condition
885 6 (KERN_INFO) informational
886 7 (KERN_DEBUG) debug-level messages
888 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
889 Format: { n | nk | nM }
890 n must be a power of two. The default size
891 is set in the kernel config file.
893 lp=0 [LP] Specify parallel ports to use, e.g,
894 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
895 lp=reset first parallel port). 'lp=0' disables the
896 lp=auto printer driver. 'lp=reset' (which can be
897 specified in addition to the ports) causes
898 attached printers to be reset. Using
899 lp=port1,port2,... specifies the parallel ports
900 to associate lp devices with, starting with
901 lp0. A port specification may be 'none' to skip
902 that lp device, or a parport name such as
903 'parport0'. Specifying 'lp=auto' instead of a
904 port specification list means that device IDs
905 from each port should be examined, to see if
906 an IEEE 1284-compliant printer is attached; if
907 so, the driver will manage that printer.
908 See also header of drivers/char/lp.c.
910 lpj=n [KNL]
911 Sets loops_per_jiffy to given constant, thus avoiding
912 time-consuming boot-time autodetection (up to 250 ms per
913 CPU). 0 enables autodetection (default). To determine
914 the correct value for your kernel, boot with normal
915 autodetection and see what value is printed. Note that
916 on SMP systems the preset will be applied to all CPUs,
917 which is likely to cause problems if your CPUs need
918 significantly divergent settings. An incorrect value
919 will cause delays in the kernel to be wrong, leading to
920 unpredictable I/O errors and other breakage. Although
921 unlikely, in the extreme case this might damage your
922 hardware.
924 ltpc= [NET]
925 Format: <io>,<irq>,<dma>
927 mac5380= [HW,SCSI] Format:
928 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
930 mac53c9x= [HW,SCSI] Format:
931 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
933 machvec= [IA64] Force the use of a particular machine-vector
934 (machvec) in a generic kernel.
935 Example: machvec=hpzx1_swiotlb
937 max_loop= [LOOP] Maximum number of loopback devices that can
938 be mounted
939 Format: <1-256>
941 maxcpus= [SMP] Maximum number of processors that an SMP kernel
942 should make use of.
943 Using "nosmp" or "maxcpus=0" will disable SMP
944 entirely (the MPS table probe still happens, though).
945 A command-line option of "maxcpus=<NUM>", where <NUM>
946 is an integer greater than 0, limits the maximum number
947 of CPUs activated in SMP mode to <NUM>.
948 Using "maxcpus=1" on an SMP kernel is the trivial
949 case of an SMP kernel with only one CPU.
951 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
952 equal to this physical address is ignored.
954 max_luns= [SCSI] Maximum number of LUNs to probe.
955 Should be between 1 and 2^32-1.
957 max_report_luns=
958 [SCSI] Maximum number of LUNs received.
959 Should be between 1 and 16384.
961 mca-pentium [BUGS=IA-32]
963 mcatest= [IA-64]
965 mcd= [HW,CD]
966 Format: <port>,<irq>,<mitsumi_bug_93_wait>
968 mcdx= [HW,CD]
970 mce [IA-32] Machine Check Exception
972 md= [HW] RAID subsystems devices and level
973 See Documentation/md.txt.
975 mdacon= [MDA]
976 Format: <first>,<last>
977 Specifies range of consoles to be captured by the MDA.
979 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
980 Amount of memory to be used when the kernel is not able
981 to see the whole system memory or for test.
982 [IA-32] Use together with memmap= to avoid physical
983 address space collisions. Without memmap= PCI devices
984 could be placed at addresses belonging to unused RAM.
986 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
987 memory.
989 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
990 E820 memory map, as specified by the user.
991 Such memmap=exactmap lines can be constructed based on
992 BIOS output or other requirements. See the memmap=nn@ss
993 option description.
995 memmap=nn[KMG]@ss[KMG]
996 [KNL] Force usage of a specific region of memory
997 Region of memory to be used, from ss to ss+nn.
999 memmap=nn[KMG]#ss[KMG]
1000 [KNL,ACPI] Mark specific memory as ACPI data.
1001 Region of memory to be used, from ss to ss+nn.
1003 memmap=nn[KMG]$ss[KMG]
1004 [KNL,ACPI] Mark specific memory as reserved.
1005 Region of memory to be used, from ss to ss+nn.
1007 meye.*= [HW] Set MotionEye Camera parameters
1008 See Documentation/video4linux/meye.txt.
1010 mga= [HW,DRM]
1012 migration_cost=
1013 [KNL,SMP] debug: override scheduler migration costs
1014 Format: <level-1-usecs>,<level-2-usecs>,...
1015 This debugging option can be used to override the
1016 default scheduler migration cost matrix. The numbers
1017 are indexed by 'CPU domain distance'.
1018 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
1019 box will set up an intra-core migration cost of
1020 1 msec, an inter-core migration cost of 2 msecs,
1021 and an inter-node migration cost of 3 msecs.
1023 WARNING: using the wrong values here can break
1024 scheduler performance, so it's only for scheduler
1025 development purposes, not production environments.
1027 migration_debug=
1028 [KNL,SMP] migration cost auto-detect verbosity
1029 Format=<0|1|2>
1030 If a system's migration matrix reported at bootup
1031 seems erroneous then this option can be used to
1032 increase verbosity of the detection process.
1033 We default to 0 (no extra messages), 1 will print
1034 some more information, and 2 will be really
1035 verbose (probably only useful if you also have a
1036 serial console attached to the system).
1038 migration_factor=
1039 [KNL,SMP] multiply/divide migration costs by a factor
1040 Format=<percent>
1041 This debug option can be used to proportionally
1042 increase or decrease the auto-detected migration
1043 costs for all entries of the migration matrix.
1044 E.g. migration_factor=150 will increase migration
1045 costs by 50%. (and thus the scheduler will be less
1046 eager migrating cache-hot tasks)
1047 migration_factor=80 will decrease migration costs
1048 by 20%. (thus the scheduler will be more eager to
1049 migrate tasks)
1051 WARNING: using the wrong values here can break
1052 scheduler performance, so it's only for scheduler
1053 development purposes, not production environments.
1055 mousedev.tap_time=
1056 [MOUSE] Maximum time between finger touching and
1057 leaving touchpad surface for touch to be considered
1058 a tap and be reported as a left button click (for
1059 touchpads working in absolute mode only).
1060 Format: <msecs>
1061 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1062 reporting absolute coordinates, such as tablets
1063 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1064 reporting absolute coordinates, such as tablets
1066 mpu401= [HW,OSS]
1067 Format: <io>,<irq>
1069 MTD_Partition= [MTD]
1070 Format: <name>,<region-number>,<size>,<offset>
1072 MTD_Region= [MTD] Format:
1073 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1075 mtdparts= [MTD]
1076 See drivers/mtd/cmdline.c.
1078 mtouchusb.raw_coordinates=
1079 [HW] Make the MicroTouch USB driver use raw coordinates
1080 ('y', default) or cooked coordinates ('n')
1082 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1084 NCR_D700= [HW,SCSI]
1085 See header of drivers/scsi/NCR_D700.c.
1087 ncr5380= [HW,SCSI]
1089 ncr53c400= [HW,SCSI]
1091 ncr53c400a= [HW,SCSI]
1093 ncr53c406a= [HW,SCSI]
1095 ncr53c8xx= [HW,SCSI]
1097 netdev= [NET] Network devices parameters
1098 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1099 Note that mem_start is often overloaded to mean
1100 something different and driver-specific.
1101 This usage is only documented in each driver source
1102 file if at all.
1104 nfsaddrs= [NFS]
1105 See Documentation/nfsroot.txt.
1107 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1108 See Documentation/nfsroot.txt.
1110 nfs.callback_tcpport=
1111 [NFS] set the TCP port on which the NFSv4 callback
1112 channel should listen.
1114 nfs.idmap_cache_timeout=
1115 [NFS] set the maximum lifetime for idmapper cache
1116 entries.
1118 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1120 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1121 emulation library even if a 387 maths coprocessor
1122 is present.
1124 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1125 when set.
1126 Format: <int>
1128 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1129 caches in the slab allocator. Saves per-node memory,
1130 but will impact performance.
1132 noalign [KNL,ARM]
1134 noapic [SMP,APIC] Tells the kernel to not make use of any
1135 IOAPICs that may be present in the system.
1137 noasync [HW,M68K] Disables async and sync negotiation for
1138 all devices.
1140 nobats [PPC] Do not use BATs for mapping kernel lowmem
1141 on "Classic" PPC cores.
1143 nocache [ARM]
1145 nodelayacct [KNL] Disable per-task delay accounting
1147 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1149 noexec [IA-64]
1151 noexec [IA-32,X86-64]
1152 noexec=on: enable non-executable mappings (default)
1153 noexec=off: disable nn-executable mappings
1155 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1156 register save and restore. The kernel will only save
1157 legacy floating-point registers on task switch.
1159 nohlt [BUGS=ARM]
1161 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1162 instruction doesn't work correctly and not to
1163 use it.
1165 nohalt [IA-64] Tells the kernel not to use the power saving
1166 function PAL_HALT_LIGHT when idle. This increases
1167 power-consumption. On the positive side, it reduces
1168 interrupt wake-up latency, which may improve performance
1169 in certain environments such as networked servers or
1170 real-time systems.
1172 nohz= [KNL] Boottime enable/disable dynamic ticks
1173 Valid arguments: on, off
1174 Default: on
1176 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1178 noirqdebug [IA-32] Disables the code which attempts to detect and
1179 disable unhandled interrupt sources.
1181 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1182 broken timer IRQ sources.
1184 noisapnp [ISAPNP] Disables ISA PnP code.
1186 noinitrd [RAM] Tells the kernel not to load any configured
1187 initial RAM disk.
1189 nointroute [IA-64]
1191 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1193 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1195 noltlbs [PPC] Do not use large page/tlb entries for kernel
1196 lowmem mapping on PPC40x.
1198 nomca [IA-64] Disable machine check abort handling
1200 nomce [IA-32] Machine Check Exception
1202 noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
1204 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1205 with UP alternatives
1207 noresidual [PPC] Don't use residual data on PReP machines.
1209 noresume [SWSUSP] Disables resume and restores original swap
1210 space.
1212 no-scroll [VGA] Disables scrollback.
1213 This is required for the Braillex ib80-piezo Braille
1214 reader made by F.H. Papenmeier (Germany).
1216 nosbagart [IA-64]
1218 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1220 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1222 nosync [HW,M68K] Disables sync negotiation for all devices.
1224 notsc [BUGS=IA-32] Disable Time Stamp Counter
1226 nousb [USB] Disable the USB subsystem
1228 nowb [ARM]
1230 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1232 opl3= [HW,OSS]
1233 Format: <io>
1235 opl3sa2= [HW,OSS] Format:
1236 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1238 oprofile.timer= [HW]
1239 Use timer interrupt instead of performance counters
1241 optcd= [HW,CD]
1242 Format: <io>
1244 osst= [HW,SCSI] SCSI Tape Driver
1245 Format: <buffer_size>,<write_threshold>
1246 See also Documentation/scsi/st.txt.
1248 panic= [KNL] Kernel behaviour on panic
1249 Format: <timeout>
1251 parkbd.port= [HW] Parallel port number the keyboard adapter is
1252 connected to, default is 0.
1253 Format: <parport#>
1254 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1255 0 for XT, 1 for AT (default is AT).
1256 Format: <mode>
1258 parport= [HW,PPT] Specify parallel ports. 0 disables.
1259 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1260 Use 'auto' to force the driver to use any
1261 IRQ/DMA settings detected (the default is to
1262 ignore detected IRQ/DMA settings because of
1263 possible conflicts). You can specify the base
1264 address, IRQ, and DMA settings; IRQ and DMA
1265 should be numbers, or 'auto' (for using detected
1266 settings on that particular port), or 'nofifo'
1267 (to avoid using a FIFO even if it is detected).
1268 Parallel ports are assigned in the order they
1269 are specified on the command line, starting
1270 with parport0.
1272 parport_init_mode= [HW,PPT]
1273 Configure VIA parallel port to operate in
1274 a specific mode. This is necessary on Pegasos
1275 computer where firmware has no options for setting
1276 up parallel port mode and sets it to spp.
1277 Currently this function knows 686a and 8231 chips.
1278 Format: [spp|ps2|epp|ecp|ecpepp]
1280 pas2= [HW,OSS] Format:
1281 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1283 pas16= [HW,SCSI]
1284 See header of drivers/scsi/pas16.c.
1286 pause_on_oops=
1287 Halt all CPUs after the first oops has been printed for
1288 the specified number of seconds. This is to be used if
1289 your oopses keep scrolling off the screen.
1291 pcbit= [HW,ISDN]
1293 pcd. [PARIDE]
1294 See header of drivers/block/paride/pcd.c.
1295 See also Documentation/paride.txt.
1297 pci=option[,option...] [PCI] various PCI subsystem options:
1298 off [IA-32] don't probe for the PCI bus
1299 bios [IA-32] force use of PCI BIOS, don't access
1300 the hardware directly. Use this if your machine
1301 has a non-standard PCI host bridge.
1302 nobios [IA-32] disallow use of PCI BIOS, only direct
1303 hardware access methods are allowed. Use this
1304 if you experience crashes upon bootup and you
1305 suspect they are caused by the BIOS.
1306 conf1 [IA-32] Force use of PCI Configuration
1307 Mechanism 1.
1308 conf2 [IA-32] Force use of PCI Configuration
1309 Mechanism 2.
1310 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1311 Configuration
1312 nomsi [MSI] If the PCI_MSI kernel config parameter is
1313 enabled, this kernel boot option can be used to
1314 disable the use of MSI interrupts system-wide.
1315 nosort [IA-32] Don't sort PCI devices according to
1316 order given by the PCI BIOS. This sorting is
1317 done to get a device order compatible with
1318 older kernels.
1319 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1320 routing table. These calls are known to be buggy
1321 on several machines and they hang the machine
1322 when used, but on other computers it's the only
1323 way to get the interrupt routing table. Try
1324 this option if the kernel is unable to allocate
1325 IRQs or discover secondary PCI buses on your
1326 motherboard.
1327 rom [IA-32] Assign address space to expansion ROMs.
1328 Use with caution as certain devices share
1329 address decoders between ROMs and other
1330 resources.
1331 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1332 assigned automatically to PCI devices. You can
1333 make the kernel exclude IRQs of your ISA cards
1334 this way.
1335 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1336 of the PIRQ table (normally generated
1337 by the BIOS) if it is outside the
1338 F0000h-100000h range.
1339 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1340 useful if the kernel is unable to find your
1341 secondary buses and you want to tell it
1342 explicitly which ones they are.
1343 assign-busses [IA-32] Always assign all PCI bus
1344 numbers ourselves, overriding
1345 whatever the firmware may have done.
1346 usepirqmask [IA-32] Honor the possible IRQ mask stored
1347 in the BIOS $PIR table. This is needed on
1348 some systems with broken BIOSes, notably
1349 some HP Pavilion N5400 and Omnibook XE3
1350 notebooks. This will have no effect if ACPI
1351 IRQ routing is enabled.
1352 noacpi [IA-32] Do not use ACPI for IRQ routing
1353 or for PCI scanning.
1354 routeirq Do IRQ routing for all PCI devices.
1355 This is normally done in pci_enable_device(),
1356 so this option is a temporary workaround
1357 for broken drivers that don't call it.
1358 firmware [ARM] Do not re-enumerate the bus but instead
1359 just use the configuration from the
1360 bootloader. This is currently used on
1361 IXP2000 systems where the bus has to be
1362 configured a certain way for adjunct CPUs.
1363 noearly [X86] Don't do any early type 1 scanning.
1364 This might help on some broken boards which
1365 machine check when some devices' config space
1366 is read. But various workarounds are disabled
1367 and some IOMMU drivers will not work.
1368 bfsort Sort PCI devices into breadth-first order.
1369 This sorting is done to get a device
1370 order compatible with older (<= 2.4) kernels.
1371 nobfsort Don't sort PCI devices into breadth-first order.
1372 cbiosize=nn[KMG] The fixed amount of bus space which is
1373 reserved for the CardBus bridge's IO window.
1374 The default value is 256 bytes.
1375 cbmemsize=nn[KMG] The fixed amount of bus space which is
1376 reserved for the CardBus bridge's memory
1377 window. The default value is 64 megabytes.
1379 pcmv= [HW,PCMCIA] BadgePAD 4
1381 pd. [PARIDE]
1382 See Documentation/paride.txt.
1384 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1385 boot time.
1386 Format: { 0 | 1 }
1387 See arch/parisc/kernel/pdc_chassis.c
1389 pf. [PARIDE]
1390 See Documentation/paride.txt.
1392 pg. [PARIDE]
1393 See Documentation/paride.txt.
1395 pirq= [SMP,APIC] Manual mp-table setup
1396 See Documentation/i386/IO-APIC.txt.
1398 plip= [PPT,NET] Parallel port network link
1399 Format: { parport<nr> | timid | 0 }
1400 See also Documentation/parport.txt.
1402 pnpacpi= [ACPI]
1403 { off }
1405 pnpbios= [ISAPNP]
1406 { on | off | curr | res | no-curr | no-res }
1408 pnp_reserve_irq=
1409 [ISAPNP] Exclude IRQs for the autoconfiguration
1411 pnp_reserve_dma=
1412 [ISAPNP] Exclude DMAs for the autoconfiguration
1414 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1415 Ranges are in pairs (I/O port base and size).
1417 pnp_reserve_mem=
1418 [ISAPNP] Exclude memory regions for the
1419 autoconfiguration.
1420 Ranges are in pairs (memory base and size).
1422 profile= [KNL] Enable kernel profiling via /proc/profile
1423 Format: [schedule,]<number>
1424 Param: "schedule" - profile schedule points.
1425 Param: <number> - step/bucket size as a power of 2 for
1426 statistical time based profiling.
1427 Param: "sleep" - profile D-state sleeping (millisecs)
1429 processor.max_cstate= [HW,ACPI]
1430 Limit processor to maximum C-state
1431 max_cstate=9 overrides any DMI blacklist limit.
1433 processor.nocst [HW,ACPI]
1434 Ignore the _CST method to determine C-states,
1435 instead using the legacy FADT method
1437 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1438 before loading.
1439 See Documentation/ramdisk.txt.
1441 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1442 probe for; one of (bare|imps|exps|lifebook|any).
1443 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1444 per second.
1445 psmouse.resetafter= [HW,MOUSE]
1446 Try to reset the device after so many bad packets
1447 (0 = never).
1448 psmouse.resolution=
1449 [HW,MOUSE] Set desired mouse resolution, in dpi.
1450 psmouse.smartscroll=
1451 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1452 0 = disabled, 1 = enabled (default).
1454 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1455 Format:
1456 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1458 pt. [PARIDE]
1459 See Documentation/paride.txt.
1461 quiet [KNL] Disable most log messages
1463 r128= [HW,DRM]
1465 raid= [HW,RAID]
1466 See Documentation/md.txt.
1468 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1469 See Documentation/ramdisk.txt.
1471 ramdisk_blocksize= [RAM]
1472 See Documentation/ramdisk.txt.
1474 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1475 New name for the ramdisk parameter.
1476 See Documentation/ramdisk.txt.
1478 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1479 RCU callbacks to process in one batch.
1481 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1482 RCU callbacks over which batch limiting is disabled.
1484 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1485 RCU callbacks below which batch limiting is re-enabled.
1487 rdinit= [KNL]
1488 Format: <full_path>
1489 Run specified binary instead of /init from the ramdisk,
1490 used for early userspace startup. See initrd.
1492 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1493 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1494 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1496 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1498 reservetop= [IA-32]
1499 Format: nn[KMG]
1500 Reserves a hole at the top of the kernel virtual
1501 address space.
1503 reset_devices [KNL] Force drivers to reset the underlying device
1504 during initialization.
1506 resume= [SWSUSP]
1507 Specify the partition device for software suspend
1509 resume_offset= [SWSUSP]
1510 Specify the offset from the beginning of the partition
1511 given by "resume=" at which the swap header is located,
1512 in <PAGE_SIZE> units (needed only for swap files).
1513 See Documentation/power/swsusp-and-swap-files.txt
1515 retain_initrd [RAM] Keep initrd memory after extraction
1517 rhash_entries= [KNL,NET]
1518 Set number of hash buckets for route cache
1520 riscom8= [HW,SERIAL]
1521 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1523 ro [KNL] Mount root device read-only on boot
1525 root= [KNL] Root filesystem
1527 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1528 mount the root filesystem
1530 rootflags= [KNL] Set root filesystem mount option string
1532 rootfstype= [KNL] Set root filesystem type
1534 rw [KNL] Mount root device read-write on boot
1536 S [KNL] Run init in single mode
1538 sa1100ir [NET]
1539 See drivers/net/irda/sa1100_ir.c.
1541 sb= [HW,OSS]
1542 Format: <io>,<irq>,<dma>,<dma2>
1544 sbni= [NET] Granch SBNI12 leased line adapter
1546 sbpcd= [HW,CD] Soundblaster CD adapter
1547 Format: <io>,<type>
1548 See a comment before function sbpcd_setup() in
1549 drivers/cdrom/sbpcd.c.
1551 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1552 Format: <io>[,<timeout>[,<isapnp>]]
1554 scsi_debug_*= [SCSI]
1555 See drivers/scsi/scsi_debug.c.
1557 scsi_default_dev_flags=
1558 [SCSI] SCSI default device flags
1559 Format: <integer>
1561 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1562 Format: <vendor>:<model>:<flags>
1563 (flags are integer value)
1565 scsi_logging= [SCSI]
1567 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1568 discovered. async scans them in kernel threads,
1569 allowing boot to proceed. none ignores them, expecting
1570 user space to do the scan.
1572 selinux [SELINUX] Disable or enable SELinux at boot time.
1573 Format: { "0" | "1" }
1574 See security/selinux/Kconfig help text.
1575 0 -- disable.
1576 1 -- enable.
1577 Default value is set via kernel config option.
1578 If enabled at boot time, /selinux/disable can be used
1579 later to disable prior to initial policy load.
1581 selinux_compat_net =
1582 [SELINUX] Set initial selinux_compat_net flag value.
1583 Format: { "0" | "1" }
1584 0 -- use new secmark-based packet controls
1585 1 -- use legacy packet controls
1586 Default value is 0 (preferred).
1587 Value can be changed at runtime via
1588 /selinux/compat_net.
1590 serialnumber [BUGS=IA-32]
1592 sg_def_reserved_size= [SCSI]
1594 shapers= [NET]
1595 Maximal number of shapers.
1597 sim710= [SCSI,HW]
1598 See header of drivers/scsi/sim710.c.
1600 simeth= [IA-64]
1601 simscsi=
1603 sjcd= [HW,CD]
1604 Format: <io>,<irq>,<dma>
1605 See header of drivers/cdrom/sjcd.c.
1607 slram= [HW,MTD]
1609 slub_debug [MM, SLUB]
1610 Enabling slub_debug allows one to determine the culprit
1611 if slab objects become corrupted. Enabling slub_debug
1612 creates guard zones around objects and poisons objects
1613 when not in use. Also tracks the last alloc / free.
1614 For more information see Documentation/vm/slub.txt.
1616 slub_max_order= [MM, SLUB]
1617 Determines the maximum allowed order for slabs. Setting
1618 this too high may cause fragmentation.
1619 For more information see Documentation/vm/slub.txt.
1621 slub_min_objects= [MM, SLUB]
1622 The minimum objects per slab. SLUB will increase the
1623 slab order up to slub_max_order to generate a
1624 sufficiently big slab to satisfy the number of objects.
1625 The higher the number of objects the smaller the overhead
1626 of tracking slabs.
1627 For more information see Documentation/vm/slub.txt.
1629 slub_min_order= [MM, SLUB]
1630 Determines the mininum page order for slabs. Must be
1631 lower than slub_max_order
1632 For more information see Documentation/vm/slub.txt.
1634 slub_nomerge [MM, SLUB]
1635 Disable merging of slabs of similar size. May be
1636 necessary if there is some reason to distinguish
1637 allocs to different slabs.
1638 For more information see Documentation/vm/slub.txt.
1640 smart2= [HW]
1641 Format: <io1>[,<io2>[,...,<io8>]]
1643 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1644 attempt to substitute SMP alternatives once at boot.
1646 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1647 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1648 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1649 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1650 smsc-ircc2.ircc_irq= [HW] IRQ line
1651 smsc-ircc2.ircc_dma= [HW] DMA channel
1652 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1653 0: Toshiba Satellite 1800 (GP data pin select)
1654 1: Fast pin select (default)
1655 2: ATC IRMode
1657 snd-ad1816a= [HW,ALSA]
1659 snd-ad1848= [HW,ALSA]
1661 snd-ali5451= [HW,ALSA]
1663 snd-als100= [HW,ALSA]
1665 snd-als4000= [HW,ALSA]
1667 snd-azt2320= [HW,ALSA]
1669 snd-cmi8330= [HW,ALSA]
1671 snd-cmipci= [HW,ALSA]
1673 snd-cs4231= [HW,ALSA]
1675 snd-cs4232= [HW,ALSA]
1677 snd-cs4236= [HW,ALSA]
1679 snd-cs4281= [HW,ALSA]
1681 snd-cs46xx= [HW,ALSA]
1683 snd-dt019x= [HW,ALSA]
1685 snd-dummy= [HW,ALSA]
1687 snd-emu10k1= [HW,ALSA]
1689 snd-ens1370= [HW,ALSA]
1691 snd-ens1371= [HW,ALSA]
1693 snd-es968= [HW,ALSA]
1695 snd-es1688= [HW,ALSA]
1697 snd-es18xx= [HW,ALSA]
1699 snd-es1938= [HW,ALSA]
1701 snd-es1968= [HW,ALSA]
1703 snd-fm801= [HW,ALSA]
1705 snd-gusclassic= [HW,ALSA]
1707 snd-gusextreme= [HW,ALSA]
1709 snd-gusmax= [HW,ALSA]
1711 snd-hdsp= [HW,ALSA]
1713 snd-ice1712= [HW,ALSA]
1715 snd-intel8x0= [HW,ALSA]
1717 snd-interwave= [HW,ALSA]
1719 snd-interwave-stb=
1720 [HW,ALSA]
1722 snd-korg1212= [HW,ALSA]
1724 snd-maestro3= [HW,ALSA]
1726 snd-mpu401= [HW,ALSA]
1728 snd-mtpav= [HW,ALSA]
1730 snd-nm256= [HW,ALSA]
1732 snd-opl3sa2= [HW,ALSA]
1734 snd-opti92x-ad1848=
1735 [HW,ALSA]
1737 snd-opti92x-cs4231=
1738 [HW,ALSA]
1740 snd-opti93x= [HW,ALSA]
1742 snd-pmac= [HW,ALSA]
1744 snd-rme32= [HW,ALSA]
1746 snd-rme96= [HW,ALSA]
1748 snd-rme9652= [HW,ALSA]
1750 snd-sb8= [HW,ALSA]
1752 snd-sb16= [HW,ALSA]
1754 snd-sbawe= [HW,ALSA]
1756 snd-serial= [HW,ALSA]
1758 snd-sgalaxy= [HW,ALSA]
1760 snd-sonicvibes= [HW,ALSA]
1762 snd-sun-amd7930=
1763 [HW,ALSA]
1765 snd-sun-cs4231= [HW,ALSA]
1767 snd-trident= [HW,ALSA]
1769 snd-usb-audio= [HW,ALSA,USB]
1771 snd-via82xx= [HW,ALSA]
1773 snd-virmidi= [HW,ALSA]
1775 snd-wavefront= [HW,ALSA]
1777 snd-ymfpci= [HW,ALSA]
1779 sonycd535= [HW,CD]
1780 Format: <io>[,<irq>]
1782 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1783 See Documentation/sonypi.txt
1785 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1786 See Documentation/specialix.txt.
1788 spia_io_base= [HW,MTD]
1789 spia_fio_base=
1790 spia_pedr=
1791 spia_peddr=
1793 sscape= [HW,OSS]
1794 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1796 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1797 See Documentation/scsi/st.txt.
1799 st0x= [HW,SCSI]
1800 See header of drivers/scsi/seagate.c.
1802 sti= [PARISC,HW]
1803 Format: <num>
1804 Set the STI (builtin display/keyboard on the HP-PARISC
1805 machines) console (graphic card) which should be used
1806 as the initial boot-console.
1807 See also comment in drivers/video/console/sticore.c.
1809 sti_font= [HW]
1810 See comment in drivers/video/console/sticore.c.
1812 stifb= [HW]
1813 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1815 sunrpc.pool_mode=
1816 [NFS]
1817 Control how the NFS server code allocates CPUs to
1818 service thread pools. Depending on how many NICs
1819 you have and where their interrupts are bound, this
1820 option will affect which CPUs will do NFS serving.
1821 Note: this parameter cannot be changed while the
1822 NFS server is running.
1824 auto the server chooses an appropriate mode
1825 automatically using heuristics
1826 global a single global pool contains all CPUs
1827 percpu one pool for each CPU
1828 pernode one pool for each NUMA node (equivalent
1829 to global on non-NUMA machines)
1831 swiotlb= [IA-64] Number of I/O TLB slabs
1833 switches= [HW,M68k]
1835 sym53c416= [HW,SCSI]
1836 See header of drivers/scsi/sym53c416.c.
1838 sysrq_always_enabled
1839 [KNL]
1840 Ignore sysrq setting - this boot parameter will
1841 neutralize any effect of /proc/sys/kernel/sysrq.
1842 Useful for debugging.
1844 t128= [HW,SCSI]
1845 See header of drivers/scsi/t128.c.
1847 tdfx= [HW,DRM]
1849 thash_entries= [KNL,NET]
1850 Set number of hash buckets for TCP connection
1852 time Show timing data prefixed to each printk message line
1854 tipar.timeout= [HW,PPT]
1855 Set communications timeout in tenths of a second
1856 (default 15).
1858 tipar.delay= [HW,PPT]
1859 Set inter-bit delay in microseconds (default 10).
1861 tmc8xx= [HW,SCSI]
1862 See header of drivers/scsi/seagate.c.
1864 tmscsim= [HW,SCSI]
1865 See comment before function dc390_setup() in
1866 drivers/scsi/tmscsim.c.
1868 tp720= [HW,PS2]
1870 trix= [HW,OSS] MediaTrix AudioTrix Pro
1871 Format:
1872 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1874 tsdev.xres= [TS] Horizontal screen resolution.
1875 tsdev.yres= [TS] Vertical screen resolution.
1877 turbografx.map[2|3]= [HW,JOY]
1878 TurboGraFX parallel port interface
1879 Format:
1880 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1881 See also Documentation/input/joystick-parport.txt
1883 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1884 See header of drivers/scsi/u14-34f.c.
1886 uart401= [HW,OSS]
1887 Format: <io>,<irq>
1889 uart6850= [HW,OSS]
1890 Format: <io>,<irq>
1892 uhci-hcd.ignore_oc=
1893 [USB] Ignore overcurrent events (default N).
1894 Some badly-designed motherboards generate lots of
1895 bogus events, for ports that aren't wired to
1896 anything. Set this parameter to avoid log spamming.
1897 Note that genuine overcurrent events won't be
1898 reported either.
1900 usbcore.autosuspend=
1901 [USB] The autosuspend time delay (in seconds) used
1902 for newly-detected USB devices (default 2). This
1903 is the time required before an idle device will be
1904 autosuspended. Devices for which the delay is set
1905 to a negative value won't be autosuspended at all.
1907 usbhid.mousepoll=
1908 [USBHID] The interval which mice are to be polled at.
1910 vdso= [IA-32,SH]
1911 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1912 vdso=1: enable VDSO (default)
1913 vdso=0: disable VDSO mapping
1915 video= [FB] Frame buffer configuration
1916 See Documentation/fb/modedb.txt.
1918 vga= [BOOT,IA-32] Select a particular video mode
1919 See Documentation/i386/boot.txt and
1920 Documentation/svga.txt.
1921 Use vga=ask for menu.
1922 This is actually a boot loader parameter; the value is
1923 passed to the kernel using a special protocol.
1925 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1926 size of <nn>. This can be used to increase the
1927 minimum size (128MB on x86). It can also be used to
1928 decrease the size and leave more room for directly
1929 mapped kernel RAM.
1931 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1932 Format: <command>
1934 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1935 Format: <command>
1937 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1938 Format: <command>
1940 waveartist= [HW,OSS]
1941 Format: <io>,<irq>,<dma>,<dma2>
1943 wd33c93= [HW,SCSI]
1944 See header of drivers/scsi/wd33c93.c.
1946 wd7000= [HW,SCSI]
1947 See header of drivers/scsi/wd7000.c.
1949 wdt= [WDT] Watchdog
1950 See Documentation/watchdog/watchdog.txt.
1952 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1953 xd_geo= See header of drivers/block/xd.c.
1955 xirc2ps_cs= [NET,PCMCIA]
1956 Format:
1957 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1959 norandmaps Don't use address space randomization
1960 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1962 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1963 This is useful to get more information why
1964 you got a "dwarf2 unwinder stuck"
1966 ______________________________________________________________________
1968 TODO:
1970 Add documentation for ALSA options.
1971 Add more DRM drivers.