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 DRM Direct Rendering Management support is enabled.
38 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
39 EFI EFI Partitioning (GPT) is enabled
40 EIDE EIDE/ATAPI support is enabled.
41 FB The frame buffer device is enabled.
42 HW Appropriate hardware is enabled.
43 IA-32 IA-32 aka i386 architecture is enabled.
44 IA-64 IA-64 architecture is enabled.
45 IOSCHED More than one I/O scheduler is enabled.
46 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
47 ISAPNP ISA PnP code is enabled.
48 ISDN Appropriate ISDN support is enabled.
49 JOY Appropriate joystick support is enabled.
50 LIBATA Libata driver is enabled
51 LP Printer support is enabled.
52 LOOP Loopback device support is enabled.
53 M68k M68k architecture is enabled.
54 These options have more detailed description inside of
55 Documentation/m68k/kernel-options.txt.
56 MCA MCA bus support is enabled.
57 MDA MDA console support is enabled.
58 MOUSE Appropriate mouse support is enabled.
59 MSI Message Signaled Interrupts (PCI).
60 MTD MTD support is enabled.
61 NET Appropriate network support is enabled.
62 NUMA NUMA support is enabled.
63 GENERIC_TIME The generic timeofday code is enabled.
64 NFS Appropriate NFS support is enabled.
65 OSS OSS sound support is enabled.
66 PV_OPS A paravirtualized kernel
67 PARIDE The ParIDE subsystem is enabled.
68 PARISC The PA-RISC architecture is enabled.
69 PCI PCI bus support is enabled.
70 PCMCIA The PCMCIA subsystem is enabled.
71 PNP Plug & Play support is enabled.
72 PPC PowerPC architecture is enabled.
73 PPT Parallel port support is enabled.
74 PS2 Appropriate PS/2 support is enabled.
75 RAM RAM disk support is enabled.
76 S390 S390 architecture is enabled.
77 SCSI Appropriate SCSI support is enabled.
78 A lot of drivers has their options described inside of
80 SELINUX SELinux support is enabled.
81 SERIAL Serial support is enabled.
82 SH SuperH architecture is enabled.
83 SMP The kernel is an SMP kernel.
84 SPARC Sparc architecture is enabled.
85 SWSUSP Software suspend is enabled.
86 TS Appropriate touchscreen support is enabled.
87 USB USB support is enabled.
88 USBHID USB Human Interface Device support is enabled.
89 V4L Video For Linux support is enabled.
90 VGA The VGA console has been enabled.
91 VT Virtual terminal support is enabled.
92 WDT Watchdog support is enabled.
93 XT IBM PC/XT MFM hard disk support is enabled.
94 X86-64 X86-64 architecture is enabled.
95 More X86-64 boot options can be found in
96 Documentation/x86_64/boot-options.txt .
98 In addition, the following text indicates that the option:
100 BUGS= Relates to possible processor bugs on the said processor.
101 KNL Is a kernel start-up parameter.
102 BOOT Is a boot loader parameter.
104 Parameters denoted with BOOT are actually interpreted by the boot
105 loader, and have no meaning to the kernel directly.
106 Do not modify the syntax of boot loader parameters without extreme
107 need or coordination with <Documentation/i386/boot.txt>.
109 There are also arch-specific kernel-parameters not documented here.
110 See for example <Documentation/x86_64/boot-options.txt>.
112 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
113 a trailing = on the name of any parameter states that that parameter will
114 be entered as an environment variable, whereas its absence indicates that
115 it will appear as a kernel argument readable via /proc/cmdline by programs
116 running once the system is up.
118 The number of kernel parameters is not limited, but the length of the
119 complete command line (parameters including spaces etc.) is limited to
120 a fixed number of characters. This limit depends on the architecture
121 and is between 256 and 4096 characters. It is defined in the file
122 ./include/asm/setup.h as COMMAND_LINE_SIZE.
125 53c7xx= [HW,SCSI] Amiga SCSI controllers
126 See header of drivers/scsi/53c7xx.c.
127 See also Documentation/scsi/ncr53c7xx.txt.
129 acpi= [HW,ACPI,X86-64,i386]
130 Advanced Configuration and Power Interface
131 Format: { force | off | ht | strict | noirq }
132 force -- enable ACPI if default was off
133 off -- disable ACPI if default was on
134 noirq -- do not use ACPI for IRQ routing
135 ht -- run only enough ACPI to enable Hyper Threading
136 strict -- Be less tolerant of platforms that are not
137 strictly ACPI specification compliant.
139 See also Documentation/pm.txt, pci=noacpi
141 acpi_apic_instance= [ACPI, IOAPIC]
143 2: use 2nd APIC table, if available
144 1,0: use 1st APIC table
147 acpi_sleep= [HW,ACPI] Sleep options
148 Format: { s3_bios, s3_mode }
149 See Documentation/power/video.txt
151 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
152 Format: { level | edge | high | low }
154 acpi_irq_balance [HW,ACPI]
155 ACPI will balance active IRQs
158 acpi_irq_nobalance [HW,ACPI]
159 ACPI will not move active IRQs (default)
162 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
164 Format: <irq>,<irq>...
166 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
167 Format: <irq>,<irq>...
169 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
170 Format: To spoof as Windows 98: ="Microsoft Windows"
172 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
173 acpi_osi="string1" # add string1 -- only one string
174 acpi_osi="!string2" # remove built-in string2
175 acpi_osi= # disable all strings
177 acpi_serialize [HW,ACPI] force serialization of AML methods
179 acpi_skip_timer_override [HW,ACPI]
180 Recognize and ignore IRQ0/pin2 Interrupt Override.
181 For broken nForce2 BIOS resulting in XT-PIC timer.
182 acpi_use_timer_override [HW,ACPI}
183 Use timer override. For some broken Nvidia NF5 boards
184 that require a timer override, but don't have
187 acpi.debug_layer= [HW,ACPI]
189 Each bit of the <int> indicates an ACPI debug layer,
190 1: enable, 0: disable. It is useful for boot time
191 debugging. After system has booted up, it can be set
192 via /sys/module/acpi/parameters/debug_layer.
193 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
194 Available bits (add the numbers together) to enable debug output
195 for specific parts of the ACPI subsystem:
196 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
197 0x10 namespace 0x20 parser 0x40 dispatcher
198 0x80 executer 0x100 resources 0x200 acpica debugger
199 0x400 os services 0x800 acpica disassembler.
200 The number can be in decimal or prefixed with 0x in hex.
201 Warning: Many of these options can produce a lot of
202 output and make your system unusable. Be very careful.
204 acpi.debug_level= [HW,ACPI]
206 Each bit of the <int> indicates an ACPI debug level,
207 1: enable, 0: disable. It is useful for boot time
208 debugging. After system has booted up, it can be set
209 via /sys/module/acpi/parameters/debug_level.
210 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
211 Available bits (add the numbers together) to enable different
212 debug output levels of the ACPI subsystem:
213 0x01 error 0x02 warn 0x04 init 0x08 debug object
214 0x10 info 0x20 init names 0x40 parse 0x80 load
215 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
216 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
217 0x10000 resources 0x20000 user requests 0x40000 package.
218 The number can be in decimal or prefixed with 0x in hex.
219 Warning: Many of these options can produce a lot of
220 output and make your system unusable. Be very careful.
223 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
225 acpi_pm_good [IA-32,X86-64]
226 Override the pmtimer bug detection: force the kernel
227 to assume that this machine's pmtimer latches its value
228 and always returns good values.
230 enable_timer_pin_1 [i386,x86-64]
231 Enable PIN 1 of APIC timer
232 Can be useful to work around chipset bugs
233 (in particular on some ATI chipsets).
234 The kernel tries to set a reasonable default.
236 disable_timer_pin_1 [i386,x86-64]
237 Disable PIN 1 of APIC timer
238 Can be useful to work around chipset bugs.
241 Format: <io>,<irq>,<dma>,<dma2>,<type>
244 See header of drivers/scsi/advansys.c.
246 advwdt= [HW,WDT] Advantech WDT
247 Format: <iostart>,<iostop>
249 aedsp16= [HW,OSS] Audio Excel DSP 16
250 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
251 See also header of sound/oss/aedsp16.c.
254 See Documentation/scsi/aha152x.txt.
257 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
260 See Documentation/scsi/aic7xxx.txt.
263 See Documentation/scsi/aic79xx.txt.
265 amijoy.map= [HW,JOY] Amiga joystick support
266 Map of devices attached to JOY0DAT and JOY1DAT
268 See also Documentation/kernel/input/joystick.txt
270 analog.map= [HW,JOY] Analog joystick and gamepad support
271 Specifies type or capabilities of an analog joystick
272 connected to one of 16 gameports
273 Format: <type1>,<type2>,..<type16>
276 Power management functions (SPARCstation-4/5 + deriv.)
278 Disable APC CPU standby support. SPARCstation-Fox does
279 not play well with APC CPU idle - disable it if you have
280 APC and your system crashes randomly.
282 apic= [APIC,i386] Change the output verbosity whilst booting
283 Format: { quiet (default) | verbose | debug }
284 Change the amount of debugging information output
285 when initialising the APIC and IO-APIC components.
287 apm= [APM] Advanced Power Management
288 See header of arch/i386/kernel/apm.c.
293 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
294 Format: <io>,<irq>,<nodeID>
298 atarimouse= [HW,MOUSE] Atari Mouse
300 atascsi= [HW,SCSI] Atari SCSI
302 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
303 EzKey and similar keyboards
305 atkbd.reset= [HW] Reset keyboard during initialization
307 atkbd.set= [HW] Select keyboard code set
308 Format: <int> (2 = AT (default), 3 = PS/2)
310 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
313 atkbd.softraw= [HW] Choose between synthetic and real raw mode
314 Format: <bool> (0 = real, 1 = synthetic (default))
316 atkbd.softrepeat= [HW]
317 Use software keyboard repeat
321 baycom_epp= [HW,AX25]
324 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
326 See header of drivers/net/hamradio/baycom_par.c.
328 baycom_ser_fdx= [HW,AX25]
329 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
330 Format: <io>,<irq>,<mode>[,<baud>]
331 See header of drivers/net/hamradio/baycom_ser_fdx.c.
333 baycom_ser_hdx= [HW,AX25]
334 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
335 Format: <io>,<irq>,<mode>
336 See header of drivers/net/hamradio/baycom_ser_hdx.c.
338 blkmtd_device= [HW,MTD]
344 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
345 bttv.radio= Most important insmod options are available as
347 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
348 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
351 See drivers/scsi/BusLogic.c, comment before function
352 BusLogic_ParseDriverOptions().
354 c101= [NET] Moxa C101 synchronous serial card
356 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
357 Sometimes CPU hardware bugs make them report the cache
358 size incorrectly. The kernel will attempt work arounds
359 to fix known problems, but for some CPUs it is not
360 possible to determine what the correct size should be.
361 This option provides an override for these situations.
363 chandev= [HW,NET] Generic channel device initialisation
365 checkreqprot [SELINUX] Set initial checkreqprot flag value.
366 Format: { "0" | "1" }
367 See security/selinux/Kconfig help text.
368 0 -- check protection applied by kernel (includes
369 any implied execute protection).
370 1 -- check protection requested by application.
371 Default value is set via a kernel config option.
372 Value can be changed at runtime via
373 /selinux/checkreqprot.
375 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
377 Forces specified clocksource (if available) to be used
378 when calculating gettimeofday(). If specified
379 clocksource is not available, it defaults to PIT.
380 Format: { pit | tsc | cyclone | pmtmr }
382 clocksource= [GENERIC_TIME] Override the default clocksource
384 Override the default clocksource and use the clocksource
385 with the name specified.
386 Some clocksource names to choose from, depending on
388 [all] jiffies (this is the base, fallback clocksource)
390 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
391 pxa_timer,timer3,32k_counter,timer0_1
393 [IA-32] pit,hpet,tsc,vmi-timer;
394 scx200_hrt on Geode; cyclone on IBM x440
402 code_bytes [IA32] How many bytes of object code to print in an
409 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
410 over the 8254 in addition to over the IO-APIC. The
411 kernel tries to set a sensible default.
413 hpet= [IA-32,HPET] option to disable HPET and use PIT.
416 com20020= [HW,NET] ARCnet - COM20020 chipset
418 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
420 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
424 ARCnet - COM90xx chipset (memory-mapped buffers)
425 Format: <io>[,<irq>[,<memstart>]]
427 condev= [HW,S390] console device
430 console= [KNL] Output console device and options.
432 tty<n> Use the virtual console device <n>.
436 Use the specified serial port. The options are of
437 the form "bbbbpnf", where "bbbb" is the baud rate,
438 "p" is parity ("n", "o", or "e"), "n" is number of
439 bits, and "f" is flow control ("r" for RTS or
440 omit it). Default is "9600n8".
442 See Documentation/serial-console.txt for more
444 Documentation/networking/netconsole.txt for an
447 uart[8250],io,<addr>[,options]
448 uart[8250],mmio,<addr>[,options]
449 Start an early, polled-mode console on the 8250/16550
450 UART at the specified I/O port or MMIO address,
451 switching to the matching ttyS device later. The
452 options are the same as for ttyS, above.
454 earlycon= [KNL] Output early console device and options.
455 uart[8250],io,<addr>[,options]
456 uart[8250],mmio,<addr>[,options]
457 Start an early, polled-mode console on the 8250/16550
458 UART at the specified I/O port or MMIO address.
459 The options are the same as for ttyS, above.
461 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
463 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
466 Format: { parport<nr> | auto | none }
468 crashkernel=nn[KMG]@ss[KMG]
469 [KNL] Reserve a chunk of physical memory to
470 hold a kernel to switch to with kexec on panic.
473 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
478 cs89x0_media= [HW,NET]
479 Format: { rj45 | aui | bnc }
481 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
484 See header of drivers/s390/block/dasd_devmap.c.
486 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
487 (one device per port)
488 Format: <port#>,<type>
489 See also Documentation/input/joystick-parport.txt
491 debug [KNL] Enable kernel debugging (events log level).
494 [KNL] verbose self-tests
496 Print debugging info while doing the locking API
498 We default to 0 (no extra messages), setting it to
499 1 will print _a lot_ more information - normally
500 only useful to kernel developers.
503 Format: <area>[,<node>]
504 See also Documentation/networking/decnet.txt.
507 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
508 Change the default blue palette of the console.
509 This is a 16-member array composed of values
513 Format: <green0>,<green1>,<green2>,...,<green15>
514 Change the default green palette of the console.
515 This is a 16-member array composed of values
519 Format: <red0>,<red1>,<red2>,...,<red15>
520 Change the default red palette of the console.
521 This is a 16-member array composed of values
526 Set system-wide default UTF-8 mode for all tty's.
527 Default is 0 and by setting to 1, it enables UTF-8
528 mode for all newly opened or allocated terminals.
531 Set number of hash buckets for dentry cache.
534 IO parameters + enable/disable command.
536 digiepca= [HW,SERIAL]
537 See drivers/char/README.epca and
538 Documentation/digiepca.txt.
540 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
542 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
544 dmasound= [HW,OSS] Sound subsystem buffers
550 earlyprintk= [IA-32,X86-64,SH]
552 earlyprintk=serial[,ttySn[,baudrate]]
554 Append ",keep" to not disable it when the real console
557 Only vga or serial at a time, not both.
559 Currently only ttyS0 and ttyS1 are supported.
561 Interaction with the standard serial driver is not
564 The VGA output is eventually overwritten by the real
569 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
572 non-0: interrupt mode (default)
579 Format: {"of[f]" | "sk[ipmbr]"}
580 See comment in arch/i386/boot/edd.S
583 Format: <id>,<membase>,<irq>
585 eisa_irq_edge= [PARISC,HW]
586 See header of drivers/parisc/eisa.c.
589 See comment before function elanfreq_setup() in
590 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
593 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
594 See Documentation/block/as-iosched.txt and
595 Documentation/block/deadline-iosched.txt for details.
597 elfcorehdr= [IA-32, X86_64]
598 Specifies physical address of start of kernel core
599 image elf header. Generally kexec loader will
600 pass this option to capture kernel.
601 See Documentation/kdump/kdump.txt for details.
603 enforcing [SELINUX] Set initial enforcing status.
605 See security/selinux/Kconfig help text.
606 0 -- permissive (log only, no denials).
607 1 -- enforcing (deny and log).
609 Value can be changed at runtime via /selinux/enforce.
612 Format: <spdif>,[<nomix>,[<amplifier>]]
613 See also header of sound/oss/es1371.c.
615 ether= [HW,NET] Ethernet cards parameters
616 This option is obsoleted by the "netdev=" option, which
617 has equivalent usage. See its documentation for details.
619 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
624 fail_make_request=[KNL]
625 General fault injection mechanism.
626 Format: <interval>,<probability>,<space>,<times>
627 See also /Documentation/fault-injection/.
630 See header of drivers/scsi/fd_mcs.c.
633 See header of drivers/scsi/fdomain.c.
636 See Documentation/floppy.txt.
639 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
640 support via parallel port (up to 5 devices per port)
641 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
642 See also Documentation/input/joystick-parport.txt
647 See header of drivers/scsi/gdth.c.
649 gpt [EFI] Forces disk with valid GPT signature but
650 invalid Protective MBR to be treated as GPT.
654 hashdist= [KNL,NUMA] Large hashes allocated during boot
655 are distributed across NUMA nodes. Defaults on
656 for IA-64, off otherwise.
657 Format: 0 | 1 (for off | on)
659 hcl= [IA-64] SGI's Hardware Graph compatibility layer
661 hd= [EIDE] (E)IDE hard drive subsystem geometry
662 Format: <cyl>,<head>,<sect>
664 hd?= [HW] (E)IDE subsystem
665 hd?lun= See Documentation/ide.txt.
667 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
668 size of <nn>. This works even on boxes that have no
669 highmem otherwise. This also works to reduce highmem
670 size on bigger boxes.
672 highres= [KNL] Enable/disable high resolution timer mode.
673 Valid parameters: "on", "off"
677 See Documentation/isdn/README.HiSax.
679 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
681 i8042.direct [HW] Put keyboard port into non-translated mode
682 i8042.dumbkbd [HW] Pretend that controller can only read data from
683 keyboard and cannot control its state
684 (Don't attempt to blink the leds)
685 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
686 i8042.nokbd [HW] Don't check/create keyboard port
687 i8042.nomux [HW] Don't check presence of an active multiplexing
689 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
692 [HW] Frequency with which keyboard LEDs should blink
693 when kernel panics (default is 0.5 sec)
694 i8042.reset [HW] Reset the controller during init and cleanup
695 i8042.unlock [HW] Unlock (ignore) the keylock
699 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
700 indicates that the driver is running on unsupported
702 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
703 does not match list of supported models.
705 [HW] Report power status in /proc/i8k
706 (disabled by default)
707 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
710 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
711 See Documentation/mca.txt.
714 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
716 ide= [HW] (E)IDE subsystem
717 Format: ide=nodma or ide=doubler or ide=reverse
718 See Documentation/ide.txt.
720 ide?= [HW] (E)IDE subsystem
721 Format: ide?=noprobe or chipset specific parameters.
722 See Documentation/ide.txt.
724 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
725 See Documentation/ide.txt.
728 Format: idle=poll or idle=mwait
729 Poll forces a polling idle loop that can slightly improves the performance
730 of waking up a idle CPU, but will use a lot of power and make the system
731 run hot. Not recommended.
732 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
733 to not use it because it doesn't save as much power as a normal idle
734 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
737 ignore_loglevel [KNL]
738 Ignore loglevel setting - this will print /all/
739 kernel messages to the console. Useful for debugging.
742 Set number of hash buckets for inode cache.
745 See header of drivers/scsi/in2000.c.
749 Run specified binary instead of /sbin/init as init
752 initcall_debug [KNL] Trace initcalls as they are executed. Useful
753 for working out where the kernel is dying during
756 initrd= [BOOT] Specify the location of the initial ramdisk
758 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
763 io7= [HW] IO7 for Marvel based alpha systems
764 See comment before marvel_specify_io7 in
765 arch/alpha/kernel/core_marvel.c.
768 See Documentation/nfsroot.txt.
770 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
771 See comment before ip2_setup() in drivers/char/ip2.c.
773 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
774 See header of drivers/scsi/ips.c.
776 ports= [IP_VS_FTP] IPVS ftp helper module
778 Up to 8 (IP_VS_APP_MAX_PORTS) ports
780 Format: <port>,<port>....
783 When an interrupt is not handled search all handlers
784 for it. Intended to get systems with badly broken
788 When an interrupt is not handled search all handlers
789 for it. Also check all handlers each timer
790 interrupt. Intended to get systems with badly broken
794 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
796 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
798 <cpu number>,...,<cpu number>
800 <cpu number>-<cpu number> (must be a positive range in ascending order)
802 <cpu number>,...,<cpu number>-<cpu number>
803 This option can be used to specify one or more CPUs
804 to isolate from the general SMP balancing and scheduling
805 algorithms. The only way to move a process onto or off
806 an "isolated" CPU is via the CPU affinity syscalls.
807 <cpu number> begins at 0 and the maximum value is
808 "number of CPUs in system - 1".
810 This option is the preferred way to isolate CPUs. The
811 alternative -- manually setting the CPU mask of all
812 tasks in the system -- can cause problems and
813 suboptimal load balancer performance.
817 js= [HW,JOY] Analog joystick
818 See Documentation/input/joystick.txt.
822 kstack=N [IA-32,X86-64] Print N words from the kernel stack
827 lapic [IA-32,APIC] Enable the local APIC even if BIOS
830 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
833 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
834 Format: addr:<io>,irq:<irq>
836 legacy_serial.force [HW,IA-32,X86-64]
837 Probe for COM ports at legacy addresses even
838 if PNPBIOS or ACPI should describe them. This
839 is for working around firmware defects.
841 llsc*= [IA64] See function print_params() in
842 arch/ia64/sn/kernel/llsc4.c.
844 load_ramdisk= [RAM] List of ramdisks to load from floppy
845 See Documentation/ramdisk.txt.
847 lockd.nlm_grace_period=P [NFS] Assign grace period.
850 lockd.nlm_tcpport=N [NFS] Assign TCP port.
853 lockd.nlm_timeout=T [NFS] Assign timeout value.
856 lockd.nlm_udpport=M [NFS] Assign UDP port.
859 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
862 loglevel= All Kernel Messages with a loglevel smaller than the
863 console loglevel will be printed to the console. It can
864 also be changed with klogd or other programs. The
865 loglevels are defined as follows:
867 0 (KERN_EMERG) system is unusable
868 1 (KERN_ALERT) action must be taken immediately
869 2 (KERN_CRIT) critical conditions
870 3 (KERN_ERR) error conditions
871 4 (KERN_WARNING) warning conditions
872 5 (KERN_NOTICE) normal but significant condition
873 6 (KERN_INFO) informational
874 7 (KERN_DEBUG) debug-level messages
876 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
877 Format: { n | nk | nM }
878 n must be a power of two. The default size
879 is set in the kernel config file.
881 lp=0 [LP] Specify parallel ports to use, e.g,
882 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
883 lp=reset first parallel port). 'lp=0' disables the
884 lp=auto printer driver. 'lp=reset' (which can be
885 specified in addition to the ports) causes
886 attached printers to be reset. Using
887 lp=port1,port2,... specifies the parallel ports
888 to associate lp devices with, starting with
889 lp0. A port specification may be 'none' to skip
890 that lp device, or a parport name such as
891 'parport0'. Specifying 'lp=auto' instead of a
892 port specification list means that device IDs
893 from each port should be examined, to see if
894 an IEEE 1284-compliant printer is attached; if
895 so, the driver will manage that printer.
896 See also header of drivers/char/lp.c.
899 Sets loops_per_jiffy to given constant, thus avoiding
900 time-consuming boot-time autodetection (up to 250 ms per
901 CPU). 0 enables autodetection (default). To determine
902 the correct value for your kernel, boot with normal
903 autodetection and see what value is printed. Note that
904 on SMP systems the preset will be applied to all CPUs,
905 which is likely to cause problems if your CPUs need
906 significantly divergent settings. An incorrect value
907 will cause delays in the kernel to be wrong, leading to
908 unpredictable I/O errors and other breakage. Although
909 unlikely, in the extreme case this might damage your
913 Format: <io>,<irq>,<dma>
915 mac5380= [HW,SCSI] Format:
916 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
918 mac53c9x= [HW,SCSI] Format:
919 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
921 machvec= [IA64] Force the use of a particular machine-vector
922 (machvec) in a generic kernel.
923 Example: machvec=hpzx1_swiotlb
925 max_loop= [LOOP] Maximum number of loopback devices that can
929 maxcpus= [SMP] Maximum number of processors that an SMP kernel
931 Using "nosmp" or "maxcpus=0" will disable SMP
932 entirely (the MPS table probe still happens, though).
933 A command-line option of "maxcpus=<NUM>", where <NUM>
934 is an integer greater than 0, limits the maximum number
935 of CPUs activated in SMP mode to <NUM>.
936 Using "maxcpus=1" on an SMP kernel is the trivial
937 case of an SMP kernel with only one CPU.
939 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
940 equal to this physical address is ignored.
942 max_luns= [SCSI] Maximum number of LUNs to probe.
943 Should be between 1 and 2^32-1.
946 [SCSI] Maximum number of LUNs received.
947 Should be between 1 and 16384.
949 mca-pentium [BUGS=IA-32]
953 mce [IA-32] Machine Check Exception
955 md= [HW] RAID subsystems devices and level
956 See Documentation/md.txt.
959 Format: <first>,<last>
960 Specifies range of consoles to be captured by the MDA.
962 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
963 Amount of memory to be used when the kernel is not able
964 to see the whole system memory or for test.
965 [IA-32] Use together with memmap= to avoid physical
966 address space collisions. Without memmap= PCI devices
967 could be placed at addresses belonging to unused RAM.
969 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
972 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
973 E820 memory map, as specified by the user.
974 Such memmap=exactmap lines can be constructed based on
975 BIOS output or other requirements. See the memmap=nn@ss
978 memmap=nn[KMG]@ss[KMG]
979 [KNL] Force usage of a specific region of memory
980 Region of memory to be used, from ss to ss+nn.
982 memmap=nn[KMG]#ss[KMG]
983 [KNL,ACPI] Mark specific memory as ACPI data.
984 Region of memory to be used, from ss to ss+nn.
986 memmap=nn[KMG]$ss[KMG]
987 [KNL,ACPI] Mark specific memory as reserved.
988 Region of memory to be used, from ss to ss+nn.
990 meye.*= [HW] Set MotionEye Camera parameters
991 See Documentation/video4linux/meye.txt.
996 [MOUSE] Maximum time between finger touching and
997 leaving touchpad surface for touch to be considered
998 a tap and be reported as a left button click (for
999 touchpads working in absolute mode only).
1001 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1002 reporting absolute coordinates, such as tablets
1003 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1004 reporting absolute coordinates, such as tablets
1009 MTD_Partition= [MTD]
1010 Format: <name>,<region-number>,<size>,<offset>
1012 MTD_Region= [MTD] Format:
1013 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1016 See drivers/mtd/cmdline.c.
1018 mtouchusb.raw_coordinates=
1019 [HW] Make the MicroTouch USB driver use raw coordinates
1020 ('y', default) or cooked coordinates ('n')
1022 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1025 See header of drivers/scsi/NCR_D700.c.
1029 ncr53c400= [HW,SCSI]
1031 ncr53c400a= [HW,SCSI]
1033 ncr53c406a= [HW,SCSI]
1035 ncr53c8xx= [HW,SCSI]
1037 netdev= [NET] Network devices parameters
1038 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1039 Note that mem_start is often overloaded to mean
1040 something different and driver-specific.
1041 This usage is only documented in each driver source
1045 See Documentation/nfsroot.txt.
1047 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1048 See Documentation/nfsroot.txt.
1050 nfs.callback_tcpport=
1051 [NFS] set the TCP port on which the NFSv4 callback
1052 channel should listen.
1054 nfs.idmap_cache_timeout=
1055 [NFS] set the maximum lifetime for idmapper cache
1058 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1060 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1061 emulation library even if a 387 maths coprocessor
1064 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1068 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1069 caches in the slab allocator. Saves per-node memory,
1070 but will impact performance.
1074 noapic [SMP,APIC] Tells the kernel to not make use of any
1075 IOAPICs that may be present in the system.
1077 noasync [HW,M68K] Disables async and sync negotiation for
1080 nobats [PPC] Do not use BATs for mapping kernel lowmem
1081 on "Classic" PPC cores.
1085 nodelayacct [KNL] Disable per-task delay accounting
1087 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1091 noexec [IA-32,X86-64]
1092 noexec=on: enable non-executable mappings (default)
1093 noexec=off: disable nn-executable mappings
1095 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1096 register save and restore. The kernel will only save
1097 legacy floating-point registers on task switch.
1101 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1102 instruction doesn't work correctly and not to
1105 nohalt [IA-64] Tells the kernel not to use the power saving
1106 function PAL_HALT_LIGHT when idle. This increases
1107 power-consumption. On the positive side, it reduces
1108 interrupt wake-up latency, which may improve performance
1109 in certain environments such as networked servers or
1112 nohz= [KNL] Boottime enable/disable dynamic ticks
1113 Valid arguments: on, off
1116 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1118 noirqdebug [IA-32] Disables the code which attempts to detect and
1119 disable unhandled interrupt sources.
1121 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1122 broken timer IRQ sources.
1124 noisapnp [ISAPNP] Disables ISA PnP code.
1126 noinitrd [RAM] Tells the kernel not to load any configured
1131 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1133 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1135 noltlbs [PPC] Do not use large page/tlb entries for kernel
1136 lowmem mapping on PPC40x.
1138 nomca [IA-64] Disable machine check abort handling
1140 nomce [IA-32] Machine Check Exception
1142 noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
1144 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1145 with UP alternatives
1147 noresidual [PPC] Don't use residual data on PReP machines.
1149 noresume [SWSUSP] Disables resume and restores original swap
1152 no-scroll [VGA] Disables scrollback.
1153 This is required for the Braillex ib80-piezo Braille
1154 reader made by F.H. Papenmeier (Germany).
1158 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1160 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1162 nosoftlockup [KNL] Disable the soft-lockup detector.
1164 nosync [HW,M68K] Disables sync negotiation for all devices.
1166 notsc [BUGS=IA-32] Disable Time Stamp Counter
1168 nousb [USB] Disable the USB subsystem
1172 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1173 one of ['zone', 'node', 'default'] can be specified
1174 This can be set from sysctl after boot.
1175 See Documentation/sysctl/vm.txt for details.
1177 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1182 oprofile.timer= [HW]
1183 Use timer interrupt instead of performance counters
1185 osst= [HW,SCSI] SCSI Tape Driver
1186 Format: <buffer_size>,<write_threshold>
1187 See also Documentation/scsi/st.txt.
1189 panic= [KNL] Kernel behaviour on panic
1192 parkbd.port= [HW] Parallel port number the keyboard adapter is
1193 connected to, default is 0.
1195 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1196 0 for XT, 1 for AT (default is AT).
1199 parport= [HW,PPT] Specify parallel ports. 0 disables.
1200 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1201 Use 'auto' to force the driver to use any
1202 IRQ/DMA settings detected (the default is to
1203 ignore detected IRQ/DMA settings because of
1204 possible conflicts). You can specify the base
1205 address, IRQ, and DMA settings; IRQ and DMA
1206 should be numbers, or 'auto' (for using detected
1207 settings on that particular port), or 'nofifo'
1208 (to avoid using a FIFO even if it is detected).
1209 Parallel ports are assigned in the order they
1210 are specified on the command line, starting
1213 parport_init_mode= [HW,PPT]
1214 Configure VIA parallel port to operate in
1215 a specific mode. This is necessary on Pegasos
1216 computer where firmware has no options for setting
1217 up parallel port mode and sets it to spp.
1218 Currently this function knows 686a and 8231 chips.
1219 Format: [spp|ps2|epp|ecp|ecpepp]
1221 pas2= [HW,OSS] Format:
1222 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1225 See header of drivers/scsi/pas16.c.
1228 Halt all CPUs after the first oops has been printed for
1229 the specified number of seconds. This is to be used if
1230 your oopses keep scrolling off the screen.
1235 See header of drivers/block/paride/pcd.c.
1236 See also Documentation/paride.txt.
1238 pci=option[,option...] [PCI] various PCI subsystem options:
1239 off [IA-32] don't probe for the PCI bus
1240 bios [IA-32] force use of PCI BIOS, don't access
1241 the hardware directly. Use this if your machine
1242 has a non-standard PCI host bridge.
1243 nobios [IA-32] disallow use of PCI BIOS, only direct
1244 hardware access methods are allowed. Use this
1245 if you experience crashes upon bootup and you
1246 suspect they are caused by the BIOS.
1247 conf1 [IA-32] Force use of PCI Configuration
1249 conf2 [IA-32] Force use of PCI Configuration
1251 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1253 nomsi [MSI] If the PCI_MSI kernel config parameter is
1254 enabled, this kernel boot option can be used to
1255 disable the use of MSI interrupts system-wide.
1256 nosort [IA-32] Don't sort PCI devices according to
1257 order given by the PCI BIOS. This sorting is
1258 done to get a device order compatible with
1260 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1261 routing table. These calls are known to be buggy
1262 on several machines and they hang the machine
1263 when used, but on other computers it's the only
1264 way to get the interrupt routing table. Try
1265 this option if the kernel is unable to allocate
1266 IRQs or discover secondary PCI buses on your
1268 rom [IA-32] Assign address space to expansion ROMs.
1269 Use with caution as certain devices share
1270 address decoders between ROMs and other
1272 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1273 assigned automatically to PCI devices. You can
1274 make the kernel exclude IRQs of your ISA cards
1276 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1277 of the PIRQ table (normally generated
1278 by the BIOS) if it is outside the
1279 F0000h-100000h range.
1280 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1281 useful if the kernel is unable to find your
1282 secondary buses and you want to tell it
1283 explicitly which ones they are.
1284 assign-busses [IA-32] Always assign all PCI bus
1285 numbers ourselves, overriding
1286 whatever the firmware may have done.
1287 usepirqmask [IA-32] Honor the possible IRQ mask stored
1288 in the BIOS $PIR table. This is needed on
1289 some systems with broken BIOSes, notably
1290 some HP Pavilion N5400 and Omnibook XE3
1291 notebooks. This will have no effect if ACPI
1292 IRQ routing is enabled.
1293 noacpi [IA-32] Do not use ACPI for IRQ routing
1294 or for PCI scanning.
1295 routeirq Do IRQ routing for all PCI devices.
1296 This is normally done in pci_enable_device(),
1297 so this option is a temporary workaround
1298 for broken drivers that don't call it.
1299 firmware [ARM] Do not re-enumerate the bus but instead
1300 just use the configuration from the
1301 bootloader. This is currently used on
1302 IXP2000 systems where the bus has to be
1303 configured a certain way for adjunct CPUs.
1304 noearly [X86] Don't do any early type 1 scanning.
1305 This might help on some broken boards which
1306 machine check when some devices' config space
1307 is read. But various workarounds are disabled
1308 and some IOMMU drivers will not work.
1309 bfsort Sort PCI devices into breadth-first order.
1310 This sorting is done to get a device
1311 order compatible with older (<= 2.4) kernels.
1312 nobfsort Don't sort PCI devices into breadth-first order.
1313 cbiosize=nn[KMG] The fixed amount of bus space which is
1314 reserved for the CardBus bridge's IO window.
1315 The default value is 256 bytes.
1316 cbmemsize=nn[KMG] The fixed amount of bus space which is
1317 reserved for the CardBus bridge's memory
1318 window. The default value is 64 megabytes.
1320 pcmv= [HW,PCMCIA] BadgePAD 4
1323 See Documentation/paride.txt.
1325 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1328 See arch/parisc/kernel/pdc_chassis.c
1331 See Documentation/paride.txt.
1334 See Documentation/paride.txt.
1336 pirq= [SMP,APIC] Manual mp-table setup
1337 See Documentation/i386/IO-APIC.txt.
1339 plip= [PPT,NET] Parallel port network link
1340 Format: { parport<nr> | timid | 0 }
1341 See also Documentation/parport.txt.
1347 { on | off | curr | res | no-curr | no-res }
1350 [ISAPNP] Exclude IRQs for the autoconfiguration
1353 [ISAPNP] Exclude DMAs for the autoconfiguration
1355 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1356 Ranges are in pairs (I/O port base and size).
1359 [ISAPNP] Exclude memory regions for the
1361 Ranges are in pairs (memory base and size).
1363 print-fatal-signals=
1364 [KNL] debug: print fatal signals
1365 print-fatal-signals=1: print segfault info to
1369 printk.time= Show timing data prefixed to each printk message line
1370 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1372 profile= [KNL] Enable kernel profiling via /proc/profile
1373 Format: [schedule,]<number>
1374 Param: "schedule" - profile schedule points.
1375 Param: <number> - step/bucket size as a power of 2 for
1376 statistical time based profiling.
1377 Param: "sleep" - profile D-state sleeping (millisecs)
1379 processor.max_cstate= [HW,ACPI]
1380 Limit processor to maximum C-state
1381 max_cstate=9 overrides any DMI blacklist limit.
1383 processor.nocst [HW,ACPI]
1384 Ignore the _CST method to determine C-states,
1385 instead using the legacy FADT method
1387 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1389 See Documentation/ramdisk.txt.
1391 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1392 probe for; one of (bare|imps|exps|lifebook|any).
1393 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1395 psmouse.resetafter= [HW,MOUSE]
1396 Try to reset the device after so many bad packets
1399 [HW,MOUSE] Set desired mouse resolution, in dpi.
1400 psmouse.smartscroll=
1401 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1402 0 = disabled, 1 = enabled (default).
1404 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1406 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1409 See Documentation/paride.txt.
1411 quiet [KNL] Disable most log messages
1416 See Documentation/md.txt.
1418 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1419 See Documentation/ramdisk.txt.
1421 ramdisk_blocksize= [RAM]
1422 See Documentation/ramdisk.txt.
1424 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1425 New name for the ramdisk parameter.
1426 See Documentation/ramdisk.txt.
1428 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1429 RCU callbacks to process in one batch.
1431 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1432 RCU callbacks over which batch limiting is disabled.
1434 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1435 RCU callbacks below which batch limiting is re-enabled.
1439 Run specified binary instead of /init from the ramdisk,
1440 used for early userspace startup. See initrd.
1442 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1443 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1444 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1446 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1450 Reserves a hole at the top of the kernel virtual
1453 reset_devices [KNL] Force drivers to reset the underlying device
1454 during initialization.
1457 Specify the partition device for software suspend
1459 resume_offset= [SWSUSP]
1460 Specify the offset from the beginning of the partition
1461 given by "resume=" at which the swap header is located,
1462 in <PAGE_SIZE> units (needed only for swap files).
1463 See Documentation/power/swsusp-and-swap-files.txt
1465 retain_initrd [RAM] Keep initrd memory after extraction
1467 rhash_entries= [KNL,NET]
1468 Set number of hash buckets for route cache
1470 riscom8= [HW,SERIAL]
1471 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1473 ro [KNL] Mount root device read-only on boot
1475 root= [KNL] Root filesystem
1477 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1478 mount the root filesystem
1480 rootflags= [KNL] Set root filesystem mount option string
1482 rootfstype= [KNL] Set root filesystem type
1484 rootwait [KNL] Wait (indefinitely) for root device to show up.
1485 Useful for devices that are detected asynchronously
1486 (e.g. USB and MMC devices).
1488 rw [KNL] Mount root device read-write on boot
1490 S [KNL] Run init in single mode
1493 See drivers/net/irda/sa1100_ir.c.
1496 Format: <io>,<irq>,<dma>,<dma2>
1498 sbni= [NET] Granch SBNI12 leased line adapter
1500 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1501 Format: <io>[,<timeout>[,<isapnp>]]
1503 scsi_debug_*= [SCSI]
1504 See drivers/scsi/scsi_debug.c.
1506 scsi_default_dev_flags=
1507 [SCSI] SCSI default device flags
1510 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1511 Format: <vendor>:<model>:<flags>
1512 (flags are integer value)
1514 scsi_logging= [SCSI]
1516 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1517 discovered. async scans them in kernel threads,
1518 allowing boot to proceed. none ignores them, expecting
1519 user space to do the scan.
1521 selinux [SELINUX] Disable or enable SELinux at boot time.
1522 Format: { "0" | "1" }
1523 See security/selinux/Kconfig help text.
1526 Default value is set via kernel config option.
1527 If enabled at boot time, /selinux/disable can be used
1528 later to disable prior to initial policy load.
1530 selinux_compat_net =
1531 [SELINUX] Set initial selinux_compat_net flag value.
1532 Format: { "0" | "1" }
1533 0 -- use new secmark-based packet controls
1534 1 -- use legacy packet controls
1535 Default value is 0 (preferred).
1536 Value can be changed at runtime via
1537 /selinux/compat_net.
1539 serialnumber [BUGS=IA-32]
1541 sg_def_reserved_size= [SCSI]
1544 Maximal number of shapers.
1547 See header of drivers/scsi/sim710.c.
1554 slub_debug[=options[,slabs]] [MM, SLUB]
1555 Enabling slub_debug allows one to determine the
1556 culprit if slab objects become corrupted. Enabling
1557 slub_debug can create guard zones around objects and
1558 may poison objects when not in use. Also tracks the
1559 last alloc / free. For more information see
1560 Documentation/vm/slub.txt.
1562 slub_max_order= [MM, SLUB]
1563 Determines the maximum allowed order for slabs.
1564 A high setting may cause OOMs due to memory
1565 fragmentation. For more information see
1566 Documentation/vm/slub.txt.
1568 slub_min_objects= [MM, SLUB]
1569 The minimum number of objects per slab. SLUB will
1570 increase the slab order up to slub_max_order to
1571 generate a sufficiently large slab able to contain
1572 the number of objects indicated. The higher the number
1573 of objects the smaller the overhead of tracking slabs
1574 and the less frequently locks need to be acquired.
1575 For more information see Documentation/vm/slub.txt.
1577 slub_min_order= [MM, SLUB]
1578 Determines the mininum page order for slabs. Must be
1579 lower than slub_max_order.
1580 For more information see Documentation/vm/slub.txt.
1582 slub_nomerge [MM, SLUB]
1583 Disable merging of slabs with similar size. May be
1584 necessary if there is some reason to distinguish
1585 allocs to different slabs. Debug options disable
1586 merging on their own.
1587 For more information see Documentation/vm/slub.txt.
1590 Format: <io1>[,<io2>[,...,<io8>]]
1592 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1593 attempt to substitute SMP alternatives once at boot.
1595 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1596 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1597 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1598 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1599 smsc-ircc2.ircc_irq= [HW] IRQ line
1600 smsc-ircc2.ircc_dma= [HW] DMA channel
1601 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1602 0: Toshiba Satellite 1800 (GP data pin select)
1603 1: Fast pin select (default)
1606 snd-ad1816a= [HW,ALSA]
1608 snd-ad1848= [HW,ALSA]
1610 snd-ali5451= [HW,ALSA]
1612 snd-als100= [HW,ALSA]
1614 snd-als4000= [HW,ALSA]
1616 snd-azt2320= [HW,ALSA]
1618 snd-cmi8330= [HW,ALSA]
1620 snd-cmipci= [HW,ALSA]
1622 snd-cs4231= [HW,ALSA]
1624 snd-cs4232= [HW,ALSA]
1626 snd-cs4236= [HW,ALSA]
1628 snd-cs4281= [HW,ALSA]
1630 snd-cs46xx= [HW,ALSA]
1632 snd-dt019x= [HW,ALSA]
1634 snd-dummy= [HW,ALSA]
1636 snd-emu10k1= [HW,ALSA]
1638 snd-ens1370= [HW,ALSA]
1640 snd-ens1371= [HW,ALSA]
1642 snd-es968= [HW,ALSA]
1644 snd-es1688= [HW,ALSA]
1646 snd-es18xx= [HW,ALSA]
1648 snd-es1938= [HW,ALSA]
1650 snd-es1968= [HW,ALSA]
1652 snd-fm801= [HW,ALSA]
1654 snd-gusclassic= [HW,ALSA]
1656 snd-gusextreme= [HW,ALSA]
1658 snd-gusmax= [HW,ALSA]
1662 snd-ice1712= [HW,ALSA]
1664 snd-intel8x0= [HW,ALSA]
1666 snd-interwave= [HW,ALSA]
1671 snd-korg1212= [HW,ALSA]
1673 snd-maestro3= [HW,ALSA]
1675 snd-mpu401= [HW,ALSA]
1677 snd-mtpav= [HW,ALSA]
1679 snd-nm256= [HW,ALSA]
1681 snd-opl3sa2= [HW,ALSA]
1689 snd-opti93x= [HW,ALSA]
1693 snd-rme32= [HW,ALSA]
1695 snd-rme96= [HW,ALSA]
1697 snd-rme9652= [HW,ALSA]
1703 snd-sbawe= [HW,ALSA]
1705 snd-serial= [HW,ALSA]
1707 snd-sgalaxy= [HW,ALSA]
1709 snd-sonicvibes= [HW,ALSA]
1714 snd-sun-cs4231= [HW,ALSA]
1716 snd-trident= [HW,ALSA]
1718 snd-usb-audio= [HW,ALSA,USB]
1720 snd-via82xx= [HW,ALSA]
1722 snd-virmidi= [HW,ALSA]
1724 snd-wavefront= [HW,ALSA]
1726 snd-ymfpci= [HW,ALSA]
1728 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1729 See Documentation/sonypi.txt
1731 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1732 See Documentation/specialix.txt.
1734 spia_io_base= [HW,MTD]
1740 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1742 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1743 See Documentation/scsi/st.txt.
1746 See header of drivers/scsi/seagate.c.
1750 Set the STI (builtin display/keyboard on the HP-PARISC
1751 machines) console (graphic card) which should be used
1752 as the initial boot-console.
1753 See also comment in drivers/video/console/sticore.c.
1756 See comment in drivers/video/console/sticore.c.
1759 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1763 Control how the NFS server code allocates CPUs to
1764 service thread pools. Depending on how many NICs
1765 you have and where their interrupts are bound, this
1766 option will affect which CPUs will do NFS serving.
1767 Note: this parameter cannot be changed while the
1768 NFS server is running.
1770 auto the server chooses an appropriate mode
1771 automatically using heuristics
1772 global a single global pool contains all CPUs
1773 percpu one pool for each CPU
1774 pernode one pool for each NUMA node (equivalent
1775 to global on non-NUMA machines)
1777 swiotlb= [IA-64] Number of I/O TLB slabs
1781 sym53c416= [HW,SCSI]
1782 See header of drivers/scsi/sym53c416.c.
1784 sysrq_always_enabled
1786 Ignore sysrq setting - this boot parameter will
1787 neutralize any effect of /proc/sys/kernel/sysrq.
1788 Useful for debugging.
1791 See header of drivers/scsi/t128.c.
1795 thash_entries= [KNL,NET]
1796 Set number of hash buckets for TCP connection
1798 time Show timing data prefixed to each printk message line
1799 [deprecated, see 'printk.time']
1801 tipar.timeout= [HW,PPT]
1802 Set communications timeout in tenths of a second
1805 tipar.delay= [HW,PPT]
1806 Set inter-bit delay in microseconds (default 10).
1809 See header of drivers/scsi/seagate.c.
1812 See comment before function dc390_setup() in
1813 drivers/scsi/tmscsim.c.
1817 trix= [HW,OSS] MediaTrix AudioTrix Pro
1819 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1821 tsdev.xres= [TS] Horizontal screen resolution.
1822 tsdev.yres= [TS] Vertical screen resolution.
1824 turbografx.map[2|3]= [HW,JOY]
1825 TurboGraFX parallel port interface
1827 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1828 See also Documentation/input/joystick-parport.txt
1830 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1831 See header of drivers/scsi/u14-34f.c.
1840 [USB] Ignore overcurrent events (default N).
1841 Some badly-designed motherboards generate lots of
1842 bogus events, for ports that aren't wired to
1843 anything. Set this parameter to avoid log spamming.
1844 Note that genuine overcurrent events won't be
1847 usbcore.autosuspend=
1848 [USB] The autosuspend time delay (in seconds) used
1849 for newly-detected USB devices (default 2). This
1850 is the time required before an idle device will be
1851 autosuspended. Devices for which the delay is set
1852 to a negative value won't be autosuspended at all.
1855 [USBHID] The interval which mice are to be polled at.
1858 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1859 vdso=1: enable VDSO (default)
1860 vdso=0: disable VDSO mapping
1862 video= [FB] Frame buffer configuration
1863 See Documentation/fb/modedb.txt.
1865 vga= [BOOT,IA-32] Select a particular video mode
1866 See Documentation/i386/boot.txt and
1867 Documentation/svga.txt.
1868 Use vga=ask for menu.
1869 This is actually a boot loader parameter; the value is
1870 passed to the kernel using a special protocol.
1872 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1873 size of <nn>. This can be used to increase the
1874 minimum size (128MB on x86). It can also be used to
1875 decrease the size and leave more room for directly
1878 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1881 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1884 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1887 waveartist= [HW,OSS]
1888 Format: <io>,<irq>,<dma>,<dma2>
1891 See header of drivers/scsi/wd33c93.c.
1894 See header of drivers/scsi/wd7000.c.
1897 See Documentation/watchdog/watchdog.txt.
1899 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1900 xd_geo= See header of drivers/block/xd.c.
1902 xirc2ps_cs= [NET,PCMCIA]
1904 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1906 norandmaps Don't use address space randomization
1907 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1909 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1910 This is useful to get more information why
1911 you got a "dwarf2 unwinder stuck"
1913 ______________________________________________________________________
1917 Add documentation for ALSA options.
1918 Add more DRM drivers.