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-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
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]
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
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
159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
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
188 acpi.debug_layer= [HW,ACPI]
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]
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.
232 { off | try_unsupported }
233 off: disable AGP support
234 try_unsupported: try to drive unsupported chipsets
235 (may crash computer or cause data corruption)
237 enable_timer_pin_1 [i386,x86-64]
238 Enable PIN 1 of APIC timer
239 Can be useful to work around chipset bugs
240 (in particular on some ATI chipsets).
241 The kernel tries to set a reasonable default.
243 disable_timer_pin_1 [i386,x86-64]
244 Disable PIN 1 of APIC timer
245 Can be useful to work around chipset bugs.
248 Format: <io>,<irq>,<dma>,<dma2>,<type>
251 See header of drivers/scsi/advansys.c.
253 advwdt= [HW,WDT] Advantech WDT
254 Format: <iostart>,<iostop>
256 aedsp16= [HW,OSS] Audio Excel DSP 16
257 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
258 See also header of sound/oss/aedsp16.c.
261 See Documentation/scsi/aha152x.txt.
264 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
267 See Documentation/scsi/aic7xxx.txt.
270 See Documentation/scsi/aic79xx.txt.
272 amijoy.map= [HW,JOY] Amiga joystick support
273 Map of devices attached to JOY0DAT and JOY1DAT
275 See also Documentation/kernel/input/joystick.txt
277 analog.map= [HW,JOY] Analog joystick and gamepad support
278 Specifies type or capabilities of an analog joystick
279 connected to one of 16 gameports
280 Format: <type1>,<type2>,..<type16>
283 Power management functions (SPARCstation-4/5 + deriv.)
285 Disable APC CPU standby support. SPARCstation-Fox does
286 not play well with APC CPU idle - disable it if you have
287 APC and your system crashes randomly.
289 apic= [APIC,i386] Change the output verbosity whilst booting
290 Format: { quiet (default) | verbose | debug }
291 Change the amount of debugging information output
292 when initialising the APIC and IO-APIC components.
294 apm= [APM] Advanced Power Management
295 See header of arch/i386/kernel/apm.c.
300 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
301 Format: <io>,<irq>,<nodeID>
305 atarimouse= [HW,MOUSE] Atari Mouse
307 atascsi= [HW,SCSI] Atari SCSI
309 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
310 EzKey and similar keyboards
312 atkbd.reset= [HW] Reset keyboard during initialization
314 atkbd.set= [HW] Select keyboard code set
315 Format: <int> (2 = AT (default), 3 = PS/2)
317 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
320 atkbd.softraw= [HW] Choose between synthetic and real raw mode
321 Format: <bool> (0 = real, 1 = synthetic (default))
323 atkbd.softrepeat= [HW]
324 Use software keyboard repeat
328 baycom_epp= [HW,AX25]
331 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
333 See header of drivers/net/hamradio/baycom_par.c.
335 baycom_ser_fdx= [HW,AX25]
336 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
337 Format: <io>,<irq>,<mode>[,<baud>]
338 See header of drivers/net/hamradio/baycom_ser_fdx.c.
340 baycom_ser_hdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
342 Format: <io>,<irq>,<mode>
343 See header of drivers/net/hamradio/baycom_ser_hdx.c.
345 blkmtd_device= [HW,MTD]
351 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
352 bttv.radio= Most important insmod options are available as
354 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
355 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
358 See drivers/scsi/BusLogic.c, comment before function
359 BusLogic_ParseDriverOptions().
361 c101= [NET] Moxa C101 synchronous serial card
363 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
364 Sometimes CPU hardware bugs make them report the cache
365 size incorrectly. The kernel will attempt work arounds
366 to fix known problems, but for some CPUs it is not
367 possible to determine what the correct size should be.
368 This option provides an override for these situations.
370 chandev= [HW,NET] Generic channel device initialisation
372 checkreqprot [SELINUX] Set initial checkreqprot flag value.
373 Format: { "0" | "1" }
374 See security/selinux/Kconfig help text.
375 0 -- check protection applied by kernel (includes
376 any implied execute protection).
377 1 -- check protection requested by application.
378 Default value is set via a kernel config option.
379 Value can be changed at runtime via
380 /selinux/checkreqprot.
382 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
384 Forces specified clocksource (if available) to be used
385 when calculating gettimeofday(). If specified
386 clocksource is not available, it defaults to PIT.
387 Format: { pit | tsc | cyclone | pmtmr }
389 clocksource= [GENERIC_TIME] Override the default clocksource
391 Override the default clocksource and use the clocksource
392 with the name specified.
393 Some clocksource names to choose from, depending on
395 [all] jiffies (this is the base, fallback clocksource)
397 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
398 pxa_timer,timer3,32k_counter,timer0_1
400 [IA-32] pit,hpet,tsc,vmi-timer;
401 scx200_hrt on Geode; cyclone on IBM x440
409 code_bytes [IA32] How many bytes of object code to print in an
416 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
417 over the 8254 in addition to over the IO-APIC. The
418 kernel tries to set a sensible default.
420 hpet= [IA-32,HPET] option to disable HPET and use PIT.
423 com20020= [HW,NET] ARCnet - COM20020 chipset
425 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
427 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
431 ARCnet - COM90xx chipset (memory-mapped buffers)
432 Format: <io>[,<irq>[,<memstart>]]
434 condev= [HW,S390] console device
437 console= [KNL] Output console device and options.
439 tty<n> Use the virtual console device <n>.
443 Use the specified serial port. The options are of
444 the form "bbbbpnf", where "bbbb" is the baud rate,
445 "p" is parity ("n", "o", or "e"), "n" is number of
446 bits, and "f" is flow control ("r" for RTS or
447 omit it). Default is "9600n8".
449 See Documentation/serial-console.txt for more
451 Documentation/networking/netconsole.txt for an
454 uart[8250],io,<addr>[,options]
455 uart[8250],mmio,<addr>[,options]
456 Start an early, polled-mode console on the 8250/16550
457 UART at the specified I/O port or MMIO address,
458 switching to the matching ttyS device later. The
459 options are the same as for ttyS, above.
461 earlycon= [KNL] Output early console device and options.
462 uart[8250],io,<addr>[,options]
463 uart[8250],mmio,<addr>[,options]
464 Start an early, polled-mode console on the 8250/16550
465 UART at the specified I/O port or MMIO address.
466 The options are the same as for ttyS, above.
468 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
470 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
473 Format: { parport<nr> | auto | none }
475 crashkernel=nn[KMG]@ss[KMG]
476 [KNL] Reserve a chunk of physical memory to
477 hold a kernel to switch to with kexec on panic.
480 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
485 cs89x0_media= [HW,NET]
486 Format: { rj45 | aui | bnc }
488 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
491 See header of drivers/s390/block/dasd_devmap.c.
493 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
494 (one device per port)
495 Format: <port#>,<type>
496 See also Documentation/input/joystick-parport.txt
498 debug [KNL] Enable kernel debugging (events log level).
501 [KNL] verbose self-tests
503 Print debugging info while doing the locking API
505 We default to 0 (no extra messages), setting it to
506 1 will print _a lot_ more information - normally
507 only useful to kernel developers.
510 Format: <area>[,<node>]
511 See also Documentation/networking/decnet.txt.
514 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
515 Change the default blue palette of the console.
516 This is a 16-member array composed of values
520 Format: <green0>,<green1>,<green2>,...,<green15>
521 Change the default green palette of the console.
522 This is a 16-member array composed of values
526 Format: <red0>,<red1>,<red2>,...,<red15>
527 Change the default red palette of the console.
528 This is a 16-member array composed of values
533 Set system-wide default UTF-8 mode for all tty's.
534 Default is 0 and by setting to 1, it enables UTF-8
535 mode for all newly opened or allocated terminals.
538 Set number of hash buckets for dentry cache.
541 IO parameters + enable/disable command.
543 digiepca= [HW,SERIAL]
544 See drivers/char/README.epca and
545 Documentation/digiepca.txt.
547 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
549 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
551 dmasound= [HW,OSS] Sound subsystem buffers
557 earlyprintk= [IA-32,X86-64,SH]
559 earlyprintk=serial[,ttySn[,baudrate]]
561 Append ",keep" to not disable it when the real console
564 Only vga or serial at a time, not both.
566 Currently only ttyS0 and ttyS1 are supported.
568 Interaction with the standard serial driver is not
571 The VGA output is eventually overwritten by the real
576 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
579 non-0: interrupt mode (default)
586 Format: {"of[f]" | "sk[ipmbr]"}
587 See comment in arch/i386/boot/edd.S
590 Format: <id>,<membase>,<irq>
592 eisa_irq_edge= [PARISC,HW]
593 See header of drivers/parisc/eisa.c.
596 See comment before function elanfreq_setup() in
597 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
600 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
601 See Documentation/block/as-iosched.txt and
602 Documentation/block/deadline-iosched.txt for details.
604 elfcorehdr= [IA-32, X86_64]
605 Specifies physical address of start of kernel core
606 image elf header. Generally kexec loader will
607 pass this option to capture kernel.
608 See Documentation/kdump/kdump.txt for details.
610 enforcing [SELINUX] Set initial enforcing status.
612 See security/selinux/Kconfig help text.
613 0 -- permissive (log only, no denials).
614 1 -- enforcing (deny and log).
616 Value can be changed at runtime via /selinux/enforce.
619 Format: <spdif>,[<nomix>,[<amplifier>]]
620 See also header of sound/oss/es1371.c.
622 ether= [HW,NET] Ethernet cards parameters
623 This option is obsoleted by the "netdev=" option, which
624 has equivalent usage. See its documentation for details.
626 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
631 fail_make_request=[KNL]
632 General fault injection mechanism.
633 Format: <interval>,<probability>,<space>,<times>
634 See also /Documentation/fault-injection/.
637 See header of drivers/scsi/fd_mcs.c.
640 See header of drivers/scsi/fdomain.c.
643 See Documentation/floppy.txt.
646 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
647 support via parallel port (up to 5 devices per port)
648 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
649 See also Documentation/input/joystick-parport.txt
654 See header of drivers/scsi/gdth.c.
656 gpt [EFI] Forces disk with valid GPT signature but
657 invalid Protective MBR to be treated as GPT.
661 hashdist= [KNL,NUMA] Large hashes allocated during boot
662 are distributed across NUMA nodes. Defaults on
663 for IA-64, off otherwise.
664 Format: 0 | 1 (for off | on)
666 hcl= [IA-64] SGI's Hardware Graph compatibility layer
668 hd= [EIDE] (E)IDE hard drive subsystem geometry
669 Format: <cyl>,<head>,<sect>
671 hd?= [HW] (E)IDE subsystem
672 hd?lun= See Documentation/ide.txt.
674 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
675 size of <nn>. This works even on boxes that have no
676 highmem otherwise. This also works to reduce highmem
677 size on bigger boxes.
679 highres= [KNL] Enable/disable high resolution timer mode.
680 Valid parameters: "on", "off"
684 See Documentation/isdn/README.HiSax.
686 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
688 i8042.direct [HW] Put keyboard port into non-translated mode
689 i8042.dumbkbd [HW] Pretend that controller can only read data from
690 keyboard and cannot control its state
691 (Don't attempt to blink the leds)
692 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
693 i8042.nokbd [HW] Don't check/create keyboard port
694 i8042.nomux [HW] Don't check presence of an active multiplexing
696 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
699 [HW] Frequency with which keyboard LEDs should blink
700 when kernel panics (default is 0.5 sec)
701 i8042.reset [HW] Reset the controller during init and cleanup
702 i8042.unlock [HW] Unlock (ignore) the keylock
706 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
707 indicates that the driver is running on unsupported
709 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
710 does not match list of supported models.
712 [HW] Report power status in /proc/i8k
713 (disabled by default)
714 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
717 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
718 See Documentation/mca.txt.
721 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
723 ide= [HW] (E)IDE subsystem
724 Format: ide=nodma or ide=doubler or ide=reverse
725 See Documentation/ide.txt.
727 ide?= [HW] (E)IDE subsystem
728 Format: ide?=noprobe or chipset specific parameters.
729 See Documentation/ide.txt.
731 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
732 See Documentation/ide.txt.
735 Format: idle=poll or idle=mwait
736 Poll forces a polling idle loop that can slightly improves the performance
737 of waking up a idle CPU, but will use a lot of power and make the system
738 run hot. Not recommended.
739 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
740 to not use it because it doesn't save as much power as a normal idle
741 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
744 ignore_loglevel [KNL]
745 Ignore loglevel setting - this will print /all/
746 kernel messages to the console. Useful for debugging.
749 Set number of hash buckets for inode cache.
752 See header of drivers/scsi/in2000.c.
756 Run specified binary instead of /sbin/init as init
759 initcall_debug [KNL] Trace initcalls as they are executed. Useful
760 for working out where the kernel is dying during
763 initrd= [BOOT] Specify the location of the initial ramdisk
765 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
770 io7= [HW] IO7 for Marvel based alpha systems
771 See comment before marvel_specify_io7 in
772 arch/alpha/kernel/core_marvel.c.
775 See Documentation/nfsroot.txt.
777 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
778 See comment before ip2_setup() in drivers/char/ip2.c.
780 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
781 See header of drivers/scsi/ips.c.
783 ports= [IP_VS_FTP] IPVS ftp helper module
785 Up to 8 (IP_VS_APP_MAX_PORTS) ports
787 Format: <port>,<port>....
790 When an interrupt is not handled search all handlers
791 for it. Intended to get systems with badly broken
795 When an interrupt is not handled search all handlers
796 for it. Also check all handlers each timer
797 interrupt. Intended to get systems with badly broken
801 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
803 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
805 <cpu number>,...,<cpu number>
807 <cpu number>-<cpu number> (must be a positive range in ascending order)
809 <cpu number>,...,<cpu number>-<cpu number>
810 This option can be used to specify one or more CPUs
811 to isolate from the general SMP balancing and scheduling
812 algorithms. The only way to move a process onto or off
813 an "isolated" CPU is via the CPU affinity syscalls.
814 <cpu number> begins at 0 and the maximum value is
815 "number of CPUs in system - 1".
817 This option is the preferred way to isolate CPUs. The
818 alternative -- manually setting the CPU mask of all
819 tasks in the system -- can cause problems and
820 suboptimal load balancer performance.
824 js= [HW,JOY] Analog joystick
825 See Documentation/input/joystick.txt.
827 kernelcore=nn[KMG] [KNL,IA-32,IA-64,PPC,X86-64] This parameter
828 specifies the amount of memory usable by the kernel
829 for non-movable allocations. The requested amount is
830 spread evenly throughout all nodes in the system. The
831 remaining memory in each node is used for Movable
832 pages. In the event, a node is too small to have both
833 kernelcore and Movable pages, kernelcore pages will
834 take priority and other nodes will have a larger number
835 of kernelcore pages. The Movable zone is used for the
836 allocation of pages that may be reclaimed or moved
837 by the page migration subsystem. This means that
838 HugeTLB pages may not be allocated from this zone.
839 Note that allocations like PTEs-from-HighMem still
840 use the HighMem zone if it exists, and the Normal
843 movablecore=nn[KMG] [KNL,IA-32,IA-64,PPC,X86-64] This parameter
844 is similar to kernelcore except it specifies the
845 amount of memory used for migratable allocations.
846 If both kernelcore and movablecore is specified,
847 then kernelcore will be at *least* the specified
848 value but may be more. If movablecore on its own
849 is specified, the administrator must be careful
850 that the amount of memory usable for all allocations
855 kstack=N [IA-32,X86-64] Print N words from the kernel stack
860 lapic [IA-32,APIC] Enable the local APIC even if BIOS
863 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
866 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
867 Format: addr:<io>,irq:<irq>
869 legacy_serial.force [HW,IA-32,X86-64]
870 Probe for COM ports at legacy addresses even
871 if PNPBIOS or ACPI should describe them. This
872 is for working around firmware defects.
874 llsc*= [IA64] See function print_params() in
875 arch/ia64/sn/kernel/llsc4.c.
877 load_ramdisk= [RAM] List of ramdisks to load from floppy
878 See Documentation/ramdisk.txt.
880 lockd.nlm_grace_period=P [NFS] Assign grace period.
883 lockd.nlm_tcpport=N [NFS] Assign TCP port.
886 lockd.nlm_timeout=T [NFS] Assign timeout value.
889 lockd.nlm_udpport=M [NFS] Assign UDP port.
892 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
895 loglevel= All Kernel Messages with a loglevel smaller than the
896 console loglevel will be printed to the console. It can
897 also be changed with klogd or other programs. The
898 loglevels are defined as follows:
900 0 (KERN_EMERG) system is unusable
901 1 (KERN_ALERT) action must be taken immediately
902 2 (KERN_CRIT) critical conditions
903 3 (KERN_ERR) error conditions
904 4 (KERN_WARNING) warning conditions
905 5 (KERN_NOTICE) normal but significant condition
906 6 (KERN_INFO) informational
907 7 (KERN_DEBUG) debug-level messages
909 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
910 Format: { n | nk | nM }
911 n must be a power of two. The default size
912 is set in the kernel config file.
914 lp=0 [LP] Specify parallel ports to use, e.g,
915 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
916 lp=reset first parallel port). 'lp=0' disables the
917 lp=auto printer driver. 'lp=reset' (which can be
918 specified in addition to the ports) causes
919 attached printers to be reset. Using
920 lp=port1,port2,... specifies the parallel ports
921 to associate lp devices with, starting with
922 lp0. A port specification may be 'none' to skip
923 that lp device, or a parport name such as
924 'parport0'. Specifying 'lp=auto' instead of a
925 port specification list means that device IDs
926 from each port should be examined, to see if
927 an IEEE 1284-compliant printer is attached; if
928 so, the driver will manage that printer.
929 See also header of drivers/char/lp.c.
932 Sets loops_per_jiffy to given constant, thus avoiding
933 time-consuming boot-time autodetection (up to 250 ms per
934 CPU). 0 enables autodetection (default). To determine
935 the correct value for your kernel, boot with normal
936 autodetection and see what value is printed. Note that
937 on SMP systems the preset will be applied to all CPUs,
938 which is likely to cause problems if your CPUs need
939 significantly divergent settings. An incorrect value
940 will cause delays in the kernel to be wrong, leading to
941 unpredictable I/O errors and other breakage. Although
942 unlikely, in the extreme case this might damage your
946 Format: <io>,<irq>,<dma>
948 mac5380= [HW,SCSI] Format:
949 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
951 mac53c9x= [HW,SCSI] Format:
952 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
954 machvec= [IA64] Force the use of a particular machine-vector
955 (machvec) in a generic kernel.
956 Example: machvec=hpzx1_swiotlb
958 max_loop= [LOOP] Maximum number of loopback devices that can
962 maxcpus= [SMP] Maximum number of processors that an SMP kernel
964 Using "nosmp" or "maxcpus=0" will disable SMP
965 entirely (the MPS table probe still happens, though).
966 A command-line option of "maxcpus=<NUM>", where <NUM>
967 is an integer greater than 0, limits the maximum number
968 of CPUs activated in SMP mode to <NUM>.
969 Using "maxcpus=1" on an SMP kernel is the trivial
970 case of an SMP kernel with only one CPU.
972 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
973 equal to this physical address is ignored.
975 max_luns= [SCSI] Maximum number of LUNs to probe.
976 Should be between 1 and 2^32-1.
979 [SCSI] Maximum number of LUNs received.
980 Should be between 1 and 16384.
982 mca-pentium [BUGS=IA-32]
986 mce [IA-32] Machine Check Exception
988 md= [HW] RAID subsystems devices and level
989 See Documentation/md.txt.
992 Format: <first>,<last>
993 Specifies range of consoles to be captured by the MDA.
995 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
996 Amount of memory to be used when the kernel is not able
997 to see the whole system memory or for test.
998 [IA-32] Use together with memmap= to avoid physical
999 address space collisions. Without memmap= PCI devices
1000 could be placed at addresses belonging to unused RAM.
1002 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
1005 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1006 E820 memory map, as specified by the user.
1007 Such memmap=exactmap lines can be constructed based on
1008 BIOS output or other requirements. See the memmap=nn@ss
1011 memmap=nn[KMG]@ss[KMG]
1012 [KNL] Force usage of a specific region of memory
1013 Region of memory to be used, from ss to ss+nn.
1015 memmap=nn[KMG]#ss[KMG]
1016 [KNL,ACPI] Mark specific memory as ACPI data.
1017 Region of memory to be used, from ss to ss+nn.
1019 memmap=nn[KMG]$ss[KMG]
1020 [KNL,ACPI] Mark specific memory as reserved.
1021 Region of memory to be used, from ss to ss+nn.
1023 meye.*= [HW] Set MotionEye Camera parameters
1024 See Documentation/video4linux/meye.txt.
1029 [MOUSE] Maximum time between finger touching and
1030 leaving touchpad surface for touch to be considered
1031 a tap and be reported as a left button click (for
1032 touchpads working in absolute mode only).
1034 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1035 reporting absolute coordinates, such as tablets
1036 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1037 reporting absolute coordinates, such as tablets
1042 MTD_Partition= [MTD]
1043 Format: <name>,<region-number>,<size>,<offset>
1045 MTD_Region= [MTD] Format:
1046 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1049 See drivers/mtd/cmdline.c.
1051 mtouchusb.raw_coordinates=
1052 [HW] Make the MicroTouch USB driver use raw coordinates
1053 ('y', default) or cooked coordinates ('n')
1055 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1058 See header of drivers/scsi/NCR_D700.c.
1062 ncr53c400= [HW,SCSI]
1064 ncr53c400a= [HW,SCSI]
1066 ncr53c406a= [HW,SCSI]
1068 ncr53c8xx= [HW,SCSI]
1070 netdev= [NET] Network devices parameters
1071 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1072 Note that mem_start is often overloaded to mean
1073 something different and driver-specific.
1074 This usage is only documented in each driver source
1078 See Documentation/nfsroot.txt.
1080 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1081 See Documentation/nfsroot.txt.
1083 nfs.callback_tcpport=
1084 [NFS] set the TCP port on which the NFSv4 callback
1085 channel should listen.
1087 nfs.idmap_cache_timeout=
1088 [NFS] set the maximum lifetime for idmapper cache
1091 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1093 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1094 emulation library even if a 387 maths coprocessor
1097 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1101 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1102 caches in the slab allocator. Saves per-node memory,
1103 but will impact performance.
1107 noapic [SMP,APIC] Tells the kernel to not make use of any
1108 IOAPICs that may be present in the system.
1110 noasync [HW,M68K] Disables async and sync negotiation for
1113 nobats [PPC] Do not use BATs for mapping kernel lowmem
1114 on "Classic" PPC cores.
1118 nodelayacct [KNL] Disable per-task delay accounting
1120 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1124 noexec [IA-32,X86-64]
1125 noexec=on: enable non-executable mappings (default)
1126 noexec=off: disable nn-executable mappings
1128 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1129 register save and restore. The kernel will only save
1130 legacy floating-point registers on task switch.
1134 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1135 instruction doesn't work correctly and not to
1138 nohalt [IA-64] Tells the kernel not to use the power saving
1139 function PAL_HALT_LIGHT when idle. This increases
1140 power-consumption. On the positive side, it reduces
1141 interrupt wake-up latency, which may improve performance
1142 in certain environments such as networked servers or
1145 nohz= [KNL] Boottime enable/disable dynamic ticks
1146 Valid arguments: on, off
1149 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1151 noirqdebug [IA-32] Disables the code which attempts to detect and
1152 disable unhandled interrupt sources.
1154 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1155 broken timer IRQ sources.
1157 noisapnp [ISAPNP] Disables ISA PnP code.
1159 noinitrd [RAM] Tells the kernel not to load any configured
1164 nojitter [IA64] Disables jitter checking for ITC timers.
1166 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1168 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1170 noltlbs [PPC] Do not use large page/tlb entries for kernel
1171 lowmem mapping on PPC40x.
1173 nomca [IA-64] Disable machine check abort handling
1175 nomce [IA-32] Machine Check Exception
1177 noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
1179 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1180 with UP alternatives
1182 noresidual [PPC] Don't use residual data on PReP machines.
1184 noresume [SWSUSP] Disables resume and restores original swap
1187 no-scroll [VGA] Disables scrollback.
1188 This is required for the Braillex ib80-piezo Braille
1189 reader made by F.H. Papenmeier (Germany).
1193 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1195 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1197 nosoftlockup [KNL] Disable the soft-lockup detector.
1199 nosync [HW,M68K] Disables sync negotiation for all devices.
1201 notsc [BUGS=IA-32] Disable Time Stamp Counter
1203 nousb [USB] Disable the USB subsystem
1207 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1208 one of ['zone', 'node', 'default'] can be specified
1209 This can be set from sysctl after boot.
1210 See Documentation/sysctl/vm.txt for details.
1212 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1217 oprofile.timer= [HW]
1218 Use timer interrupt instead of performance counters
1220 osst= [HW,SCSI] SCSI Tape Driver
1221 Format: <buffer_size>,<write_threshold>
1222 See also Documentation/scsi/st.txt.
1224 panic= [KNL] Kernel behaviour on panic
1227 parkbd.port= [HW] Parallel port number the keyboard adapter is
1228 connected to, default is 0.
1230 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1231 0 for XT, 1 for AT (default is AT).
1234 parport= [HW,PPT] Specify parallel ports. 0 disables.
1235 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1236 Use 'auto' to force the driver to use any
1237 IRQ/DMA settings detected (the default is to
1238 ignore detected IRQ/DMA settings because of
1239 possible conflicts). You can specify the base
1240 address, IRQ, and DMA settings; IRQ and DMA
1241 should be numbers, or 'auto' (for using detected
1242 settings on that particular port), or 'nofifo'
1243 (to avoid using a FIFO even if it is detected).
1244 Parallel ports are assigned in the order they
1245 are specified on the command line, starting
1248 parport_init_mode= [HW,PPT]
1249 Configure VIA parallel port to operate in
1250 a specific mode. This is necessary on Pegasos
1251 computer where firmware has no options for setting
1252 up parallel port mode and sets it to spp.
1253 Currently this function knows 686a and 8231 chips.
1254 Format: [spp|ps2|epp|ecp|ecpepp]
1256 pas2= [HW,OSS] Format:
1257 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1260 See header of drivers/scsi/pas16.c.
1263 Halt all CPUs after the first oops has been printed for
1264 the specified number of seconds. This is to be used if
1265 your oopses keep scrolling off the screen.
1270 See header of drivers/block/paride/pcd.c.
1271 See also Documentation/paride.txt.
1273 pci=option[,option...] [PCI] various PCI subsystem options:
1274 off [IA-32] don't probe for the PCI bus
1275 bios [IA-32] force use of PCI BIOS, don't access
1276 the hardware directly. Use this if your machine
1277 has a non-standard PCI host bridge.
1278 nobios [IA-32] disallow use of PCI BIOS, only direct
1279 hardware access methods are allowed. Use this
1280 if you experience crashes upon bootup and you
1281 suspect they are caused by the BIOS.
1282 conf1 [IA-32] Force use of PCI Configuration
1284 conf2 [IA-32] Force use of PCI Configuration
1286 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1288 nomsi [MSI] If the PCI_MSI kernel config parameter is
1289 enabled, this kernel boot option can be used to
1290 disable the use of MSI interrupts system-wide.
1291 nosort [IA-32] Don't sort PCI devices according to
1292 order given by the PCI BIOS. This sorting is
1293 done to get a device order compatible with
1295 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1296 routing table. These calls are known to be buggy
1297 on several machines and they hang the machine
1298 when used, but on other computers it's the only
1299 way to get the interrupt routing table. Try
1300 this option if the kernel is unable to allocate
1301 IRQs or discover secondary PCI buses on your
1303 rom [IA-32] Assign address space to expansion ROMs.
1304 Use with caution as certain devices share
1305 address decoders between ROMs and other
1307 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1308 assigned automatically to PCI devices. You can
1309 make the kernel exclude IRQs of your ISA cards
1311 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1312 of the PIRQ table (normally generated
1313 by the BIOS) if it is outside the
1314 F0000h-100000h range.
1315 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1316 useful if the kernel is unable to find your
1317 secondary buses and you want to tell it
1318 explicitly which ones they are.
1319 assign-busses [IA-32] Always assign all PCI bus
1320 numbers ourselves, overriding
1321 whatever the firmware may have done.
1322 usepirqmask [IA-32] Honor the possible IRQ mask stored
1323 in the BIOS $PIR table. This is needed on
1324 some systems with broken BIOSes, notably
1325 some HP Pavilion N5400 and Omnibook XE3
1326 notebooks. This will have no effect if ACPI
1327 IRQ routing is enabled.
1328 noacpi [IA-32] Do not use ACPI for IRQ routing
1329 or for PCI scanning.
1330 routeirq Do IRQ routing for all PCI devices.
1331 This is normally done in pci_enable_device(),
1332 so this option is a temporary workaround
1333 for broken drivers that don't call it.
1334 firmware [ARM] Do not re-enumerate the bus but instead
1335 just use the configuration from the
1336 bootloader. This is currently used on
1337 IXP2000 systems where the bus has to be
1338 configured a certain way for adjunct CPUs.
1339 noearly [X86] Don't do any early type 1 scanning.
1340 This might help on some broken boards which
1341 machine check when some devices' config space
1342 is read. But various workarounds are disabled
1343 and some IOMMU drivers will not work.
1344 bfsort Sort PCI devices into breadth-first order.
1345 This sorting is done to get a device
1346 order compatible with older (<= 2.4) kernels.
1347 nobfsort Don't sort PCI devices into breadth-first order.
1348 cbiosize=nn[KMG] The fixed amount of bus space which is
1349 reserved for the CardBus bridge's IO window.
1350 The default value is 256 bytes.
1351 cbmemsize=nn[KMG] The fixed amount of bus space which is
1352 reserved for the CardBus bridge's memory
1353 window. The default value is 64 megabytes.
1355 pcmv= [HW,PCMCIA] BadgePAD 4
1358 See Documentation/paride.txt.
1360 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1363 See arch/parisc/kernel/pdc_chassis.c
1366 See Documentation/paride.txt.
1369 See Documentation/paride.txt.
1371 pirq= [SMP,APIC] Manual mp-table setup
1372 See Documentation/i386/IO-APIC.txt.
1374 plip= [PPT,NET] Parallel port network link
1375 Format: { parport<nr> | timid | 0 }
1376 See also Documentation/parport.txt.
1382 { on | off | curr | res | no-curr | no-res }
1385 [ISAPNP] Exclude IRQs for the autoconfiguration
1388 [ISAPNP] Exclude DMAs for the autoconfiguration
1390 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1391 Ranges are in pairs (I/O port base and size).
1394 [ISAPNP] Exclude memory regions for the
1396 Ranges are in pairs (memory base and size).
1398 print-fatal-signals=
1399 [KNL] debug: print fatal signals
1400 print-fatal-signals=1: print segfault info to
1404 printk.time= Show timing data prefixed to each printk message line
1405 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1407 profile= [KNL] Enable kernel profiling via /proc/profile
1408 Format: [schedule,]<number>
1409 Param: "schedule" - profile schedule points.
1410 Param: <number> - step/bucket size as a power of 2 for
1411 statistical time based profiling.
1412 Param: "sleep" - profile D-state sleeping (millisecs)
1414 processor.max_cstate= [HW,ACPI]
1415 Limit processor to maximum C-state
1416 max_cstate=9 overrides any DMI blacklist limit.
1418 processor.nocst [HW,ACPI]
1419 Ignore the _CST method to determine C-states,
1420 instead using the legacy FADT method
1422 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1424 See Documentation/ramdisk.txt.
1426 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1427 probe for; one of (bare|imps|exps|lifebook|any).
1428 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1430 psmouse.resetafter= [HW,MOUSE]
1431 Try to reset the device after so many bad packets
1434 [HW,MOUSE] Set desired mouse resolution, in dpi.
1435 psmouse.smartscroll=
1436 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1437 0 = disabled, 1 = enabled (default).
1439 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1441 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1444 See Documentation/paride.txt.
1446 quiet [KNL] Disable most log messages
1451 See Documentation/md.txt.
1453 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1454 See Documentation/ramdisk.txt.
1456 ramdisk_blocksize= [RAM]
1457 See Documentation/ramdisk.txt.
1459 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1460 New name for the ramdisk parameter.
1461 See Documentation/ramdisk.txt.
1463 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1464 RCU callbacks to process in one batch.
1466 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1467 RCU callbacks over which batch limiting is disabled.
1469 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1470 RCU callbacks below which batch limiting is re-enabled.
1474 Run specified binary instead of /init from the ramdisk,
1475 used for early userspace startup. See initrd.
1477 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1478 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1479 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1481 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1485 Reserves a hole at the top of the kernel virtual
1488 reset_devices [KNL] Force drivers to reset the underlying device
1489 during initialization.
1492 Specify the partition device for software suspend
1494 resume_offset= [SWSUSP]
1495 Specify the offset from the beginning of the partition
1496 given by "resume=" at which the swap header is located,
1497 in <PAGE_SIZE> units (needed only for swap files).
1498 See Documentation/power/swsusp-and-swap-files.txt
1500 retain_initrd [RAM] Keep initrd memory after extraction
1502 rhash_entries= [KNL,NET]
1503 Set number of hash buckets for route cache
1505 riscom8= [HW,SERIAL]
1506 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1508 ro [KNL] Mount root device read-only on boot
1510 root= [KNL] Root filesystem
1512 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1513 mount the root filesystem
1515 rootflags= [KNL] Set root filesystem mount option string
1517 rootfstype= [KNL] Set root filesystem type
1519 rootwait [KNL] Wait (indefinitely) for root device to show up.
1520 Useful for devices that are detected asynchronously
1521 (e.g. USB and MMC devices).
1523 rw [KNL] Mount root device read-write on boot
1525 S [KNL] Run init in single mode
1528 See drivers/net/irda/sa1100_ir.c.
1531 Format: <io>,<irq>,<dma>,<dma2>
1533 sbni= [NET] Granch SBNI12 leased line adapter
1535 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1536 Format: <io>[,<timeout>[,<isapnp>]]
1538 scsi_debug_*= [SCSI]
1539 See drivers/scsi/scsi_debug.c.
1541 scsi_default_dev_flags=
1542 [SCSI] SCSI default device flags
1545 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1546 Format: <vendor>:<model>:<flags>
1547 (flags are integer value)
1549 scsi_logging= [SCSI]
1551 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1552 discovered. async scans them in kernel threads,
1553 allowing boot to proceed. none ignores them, expecting
1554 user space to do the scan.
1556 selinux [SELINUX] Disable or enable SELinux at boot time.
1557 Format: { "0" | "1" }
1558 See security/selinux/Kconfig help text.
1561 Default value is set via kernel config option.
1562 If enabled at boot time, /selinux/disable can be used
1563 later to disable prior to initial policy load.
1565 selinux_compat_net =
1566 [SELINUX] Set initial selinux_compat_net flag value.
1567 Format: { "0" | "1" }
1568 0 -- use new secmark-based packet controls
1569 1 -- use legacy packet controls
1570 Default value is 0 (preferred).
1571 Value can be changed at runtime via
1572 /selinux/compat_net.
1574 serialnumber [BUGS=IA-32]
1576 sg_def_reserved_size= [SCSI]
1579 Maximal number of shapers.
1582 See header of drivers/scsi/sim710.c.
1589 slub_debug[=options[,slabs]] [MM, SLUB]
1590 Enabling slub_debug allows one to determine the
1591 culprit if slab objects become corrupted. Enabling
1592 slub_debug can create guard zones around objects and
1593 may poison objects when not in use. Also tracks the
1594 last alloc / free. For more information see
1595 Documentation/vm/slub.txt.
1597 slub_max_order= [MM, SLUB]
1598 Determines the maximum allowed order for slabs.
1599 A high setting may cause OOMs due to memory
1600 fragmentation. For more information see
1601 Documentation/vm/slub.txt.
1603 slub_min_objects= [MM, SLUB]
1604 The minimum number of objects per slab. SLUB will
1605 increase the slab order up to slub_max_order to
1606 generate a sufficiently large slab able to contain
1607 the number of objects indicated. The higher the number
1608 of objects the smaller the overhead of tracking slabs
1609 and the less frequently locks need to be acquired.
1610 For more information see Documentation/vm/slub.txt.
1612 slub_min_order= [MM, SLUB]
1613 Determines the mininum page order for slabs. Must be
1614 lower than slub_max_order.
1615 For more information see Documentation/vm/slub.txt.
1617 slub_nomerge [MM, SLUB]
1618 Disable merging of slabs with similar size. May be
1619 necessary if there is some reason to distinguish
1620 allocs to different slabs. Debug options disable
1621 merging on their own.
1622 For more information see Documentation/vm/slub.txt.
1625 Format: <io1>[,<io2>[,...,<io8>]]
1627 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1628 attempt to substitute SMP alternatives once at boot.
1630 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1631 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1632 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1633 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1634 smsc-ircc2.ircc_irq= [HW] IRQ line
1635 smsc-ircc2.ircc_dma= [HW] DMA channel
1636 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1637 0: Toshiba Satellite 1800 (GP data pin select)
1638 1: Fast pin select (default)
1641 snd-ad1816a= [HW,ALSA]
1643 snd-ad1848= [HW,ALSA]
1645 snd-ali5451= [HW,ALSA]
1647 snd-als100= [HW,ALSA]
1649 snd-als4000= [HW,ALSA]
1651 snd-azt2320= [HW,ALSA]
1653 snd-cmi8330= [HW,ALSA]
1655 snd-cmipci= [HW,ALSA]
1657 snd-cs4231= [HW,ALSA]
1659 snd-cs4232= [HW,ALSA]
1661 snd-cs4236= [HW,ALSA]
1663 snd-cs4281= [HW,ALSA]
1665 snd-cs46xx= [HW,ALSA]
1667 snd-dt019x= [HW,ALSA]
1669 snd-dummy= [HW,ALSA]
1671 snd-emu10k1= [HW,ALSA]
1673 snd-ens1370= [HW,ALSA]
1675 snd-ens1371= [HW,ALSA]
1677 snd-es968= [HW,ALSA]
1679 snd-es1688= [HW,ALSA]
1681 snd-es18xx= [HW,ALSA]
1683 snd-es1938= [HW,ALSA]
1685 snd-es1968= [HW,ALSA]
1687 snd-fm801= [HW,ALSA]
1689 snd-gusclassic= [HW,ALSA]
1691 snd-gusextreme= [HW,ALSA]
1693 snd-gusmax= [HW,ALSA]
1697 snd-ice1712= [HW,ALSA]
1699 snd-intel8x0= [HW,ALSA]
1701 snd-interwave= [HW,ALSA]
1706 snd-korg1212= [HW,ALSA]
1708 snd-maestro3= [HW,ALSA]
1710 snd-mpu401= [HW,ALSA]
1712 snd-mtpav= [HW,ALSA]
1714 snd-nm256= [HW,ALSA]
1716 snd-opl3sa2= [HW,ALSA]
1724 snd-opti93x= [HW,ALSA]
1728 snd-rme32= [HW,ALSA]
1730 snd-rme96= [HW,ALSA]
1732 snd-rme9652= [HW,ALSA]
1738 snd-sbawe= [HW,ALSA]
1740 snd-serial= [HW,ALSA]
1742 snd-sgalaxy= [HW,ALSA]
1744 snd-sonicvibes= [HW,ALSA]
1749 snd-sun-cs4231= [HW,ALSA]
1751 snd-trident= [HW,ALSA]
1753 snd-usb-audio= [HW,ALSA,USB]
1755 snd-via82xx= [HW,ALSA]
1757 snd-virmidi= [HW,ALSA]
1759 snd-wavefront= [HW,ALSA]
1761 snd-ymfpci= [HW,ALSA]
1763 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1764 See Documentation/sonypi.txt
1766 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1767 See Documentation/specialix.txt.
1769 spia_io_base= [HW,MTD]
1775 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1777 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1778 See Documentation/scsi/st.txt.
1781 See header of drivers/scsi/seagate.c.
1785 Set the STI (builtin display/keyboard on the HP-PARISC
1786 machines) console (graphic card) which should be used
1787 as the initial boot-console.
1788 See also comment in drivers/video/console/sticore.c.
1791 See comment in drivers/video/console/sticore.c.
1794 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1798 Control how the NFS server code allocates CPUs to
1799 service thread pools. Depending on how many NICs
1800 you have and where their interrupts are bound, this
1801 option will affect which CPUs will do NFS serving.
1802 Note: this parameter cannot be changed while the
1803 NFS server is running.
1805 auto the server chooses an appropriate mode
1806 automatically using heuristics
1807 global a single global pool contains all CPUs
1808 percpu one pool for each CPU
1809 pernode one pool for each NUMA node (equivalent
1810 to global on non-NUMA machines)
1812 swiotlb= [IA-64] Number of I/O TLB slabs
1816 sym53c416= [HW,SCSI]
1817 See header of drivers/scsi/sym53c416.c.
1819 sysrq_always_enabled
1821 Ignore sysrq setting - this boot parameter will
1822 neutralize any effect of /proc/sys/kernel/sysrq.
1823 Useful for debugging.
1826 See header of drivers/scsi/t128.c.
1830 thash_entries= [KNL,NET]
1831 Set number of hash buckets for TCP connection
1833 time Show timing data prefixed to each printk message line
1834 [deprecated, see 'printk.time']
1836 tipar.timeout= [HW,PPT]
1837 Set communications timeout in tenths of a second
1840 tipar.delay= [HW,PPT]
1841 Set inter-bit delay in microseconds (default 10).
1844 See header of drivers/scsi/seagate.c.
1847 See comment before function dc390_setup() in
1848 drivers/scsi/tmscsim.c.
1852 trix= [HW,OSS] MediaTrix AudioTrix Pro
1854 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1856 tsdev.xres= [TS] Horizontal screen resolution.
1857 tsdev.yres= [TS] Vertical screen resolution.
1859 turbografx.map[2|3]= [HW,JOY]
1860 TurboGraFX parallel port interface
1862 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1863 See also Documentation/input/joystick-parport.txt
1865 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1866 See header of drivers/scsi/u14-34f.c.
1875 [USB] Ignore overcurrent events (default N).
1876 Some badly-designed motherboards generate lots of
1877 bogus events, for ports that aren't wired to
1878 anything. Set this parameter to avoid log spamming.
1879 Note that genuine overcurrent events won't be
1882 usbcore.autosuspend=
1883 [USB] The autosuspend time delay (in seconds) used
1884 for newly-detected USB devices (default 2). This
1885 is the time required before an idle device will be
1886 autosuspended. Devices for which the delay is set
1887 to a negative value won't be autosuspended at all.
1890 [USBHID] The interval which mice are to be polled at.
1892 vdso= [IA-32,SH,x86-64]
1893 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1894 vdso=1: enable VDSO (default)
1895 vdso=0: disable VDSO mapping
1898 vector=percpu: enable percpu vector domain
1900 video= [FB] Frame buffer configuration
1901 See Documentation/fb/modedb.txt.
1903 vga= [BOOT,IA-32] Select a particular video mode
1904 See Documentation/i386/boot.txt and
1905 Documentation/svga.txt.
1906 Use vga=ask for menu.
1907 This is actually a boot loader parameter; the value is
1908 passed to the kernel using a special protocol.
1910 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1911 size of <nn>. This can be used to increase the
1912 minimum size (128MB on x86). It can also be used to
1913 decrease the size and leave more room for directly
1916 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1919 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1922 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1925 waveartist= [HW,OSS]
1926 Format: <io>,<irq>,<dma>,<dma2>
1929 See header of drivers/scsi/wd33c93.c.
1932 See header of drivers/scsi/wd7000.c.
1935 See Documentation/watchdog/watchdog.txt.
1937 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1938 xd_geo= See header of drivers/block/xd.c.
1940 xirc2ps_cs= [NET,PCMCIA]
1942 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1944 norandmaps Don't use address space randomization
1945 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1947 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1948 This is useful to get more information why
1949 you got a "dwarf2 unwinder stuck"
1951 ______________________________________________________________________
1955 Add documentation for ALSA options.
1956 Add more DRM drivers.