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 BLACKFIN Blackfin architecture is enabled.
39 DRM Direct Rendering Management support is enabled.
40 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
41 EFI EFI Partitioning (GPT) is enabled
42 EIDE EIDE/ATAPI support is enabled.
43 FB The frame buffer device is enabled.
44 HW Appropriate hardware 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 (Memory Technology Device) 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 is enabled.
68 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCIE PCI Express support is enabled.
72 PCMCIA The PCMCIA subsystem is enabled.
73 PNP Plug & Play support is enabled.
74 PPC PowerPC architecture is enabled.
75 PPT Parallel port support is enabled.
76 PS2 Appropriate PS/2 support is enabled.
77 RAM RAM disk support is enabled.
78 ROOTPLUG The example Root Plug LSM is enabled.
79 S390 S390 architecture is enabled.
80 SCSI Appropriate SCSI support is enabled.
81 A lot of drivers has their options described inside of
83 SECURITY Different security models are enabled.
84 SELINUX SELinux support is enabled.
85 SERIAL Serial support is enabled.
86 SH SuperH architecture is enabled.
87 SMP The kernel is an SMP kernel.
88 SPARC Sparc architecture is enabled.
89 SWSUSP Software suspend is enabled.
90 TS Appropriate touchscreen support is enabled.
91 USB USB support is enabled.
92 USBHID USB Human Interface Device support is enabled.
93 V4L Video For Linux support is enabled.
94 VGA The VGA console has been enabled.
95 VT Virtual terminal support is enabled.
96 WDT Watchdog support is enabled.
97 XT IBM PC/XT MFM hard disk support is enabled.
98 X86-32 X86-32, aka i386 architecture is enabled.
99 X86-64 X86-64 architecture is enabled.
100 More X86-64 boot options can be found in
101 Documentation/x86_64/boot-options.txt .
103 In addition, the following text indicates that the option:
105 BUGS= Relates to possible processor bugs on the said processor.
106 KNL Is a kernel start-up parameter.
107 BOOT Is a boot loader parameter.
109 Parameters denoted with BOOT are actually interpreted by the boot
110 loader, and have no meaning to the kernel directly.
111 Do not modify the syntax of boot loader parameters without extreme
112 need or coordination with <Documentation/i386/boot.txt>.
114 There are also arch-specific kernel-parameters not documented here.
115 See for example <Documentation/x86_64/boot-options.txt>.
117 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
118 a trailing = on the name of any parameter states that that parameter will
119 be entered as an environment variable, whereas its absence indicates that
120 it will appear as a kernel argument readable via /proc/cmdline by programs
121 running once the system is up.
123 The number of kernel parameters is not limited, but the length of the
124 complete command line (parameters including spaces etc.) is limited to
125 a fixed number of characters. This limit depends on the architecture
126 and is between 256 and 4096 characters. It is defined in the file
127 ./include/asm/setup.h as COMMAND_LINE_SIZE.
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_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
172 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
173 Format: To spoof as Windows 98: ="Microsoft Windows"
175 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
176 acpi_osi="string1" # add string1 -- only one string
177 acpi_osi="!string2" # remove built-in string2
178 acpi_osi= # disable all strings
180 acpi_serialize [HW,ACPI] force serialization of AML methods
182 acpi_skip_timer_override [HW,ACPI]
183 Recognize and ignore IRQ0/pin2 Interrupt Override.
184 For broken nForce2 BIOS resulting in XT-PIC timer.
185 acpi_use_timer_override [HW,ACPI}
186 Use timer override. For some broken Nvidia NF5 boards
187 that require a timer override, but don't have
190 acpi.debug_layer= [HW,ACPI]
192 Each bit of the <int> indicates an ACPI debug layer,
193 1: enable, 0: disable. It is useful for boot time
194 debugging. After system has booted up, it can be set
195 via /sys/module/acpi/parameters/debug_layer.
196 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
197 Available bits (add the numbers together) to enable debug output
198 for specific parts of the ACPI subsystem:
199 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
200 0x10 namespace 0x20 parser 0x40 dispatcher
201 0x80 executer 0x100 resources 0x200 acpica debugger
202 0x400 os services 0x800 acpica disassembler.
203 The number can be in decimal or prefixed with 0x in hex.
204 Warning: Many of these options can produce a lot of
205 output and make your system unusable. Be very careful.
207 acpi.debug_level= [HW,ACPI]
209 Each bit of the <int> indicates an ACPI debug level,
210 1: enable, 0: disable. It is useful for boot time
211 debugging. After system has booted up, it can be set
212 via /sys/module/acpi/parameters/debug_level.
213 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
214 Available bits (add the numbers together) to enable different
215 debug output levels of the ACPI subsystem:
216 0x01 error 0x02 warn 0x04 init 0x08 debug object
217 0x10 info 0x20 init names 0x40 parse 0x80 load
218 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
219 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
220 0x10000 resources 0x20000 user requests 0x40000 package.
221 The number can be in decimal or prefixed with 0x in hex.
222 Warning: Many of these options can produce a lot of
223 output and make your system unusable. Be very careful.
226 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
228 acpi_pm_good [X86-32,X86-64]
229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
234 { off | try_unsupported }
235 off: disable AGP support
236 try_unsupported: try to drive unsupported chipsets
237 (may crash computer or cause data corruption)
239 enable_timer_pin_1 [i386,x86-64]
240 Enable PIN 1 of APIC timer
241 Can be useful to work around chipset bugs
242 (in particular on some ATI chipsets).
243 The kernel tries to set a reasonable default.
245 disable_timer_pin_1 [i386,x86-64]
246 Disable PIN 1 of APIC timer
247 Can be useful to work around chipset bugs.
250 Format: <io>,<irq>,<dma>,<dma2>,<type>
253 See header of drivers/scsi/advansys.c.
255 advwdt= [HW,WDT] Advantech WDT
256 Format: <iostart>,<iostop>
258 aedsp16= [HW,OSS] Audio Excel DSP 16
259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
260 See also header of sound/oss/aedsp16.c.
263 See Documentation/scsi/aha152x.txt.
266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
269 See Documentation/scsi/aic7xxx.txt.
272 See Documentation/scsi/aic79xx.txt.
274 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT
277 See also Documentation/kernel/input/joystick.txt
279 analog.map= [HW,JOY] Analog joystick and gamepad support
280 Specifies type or capabilities of an analog joystick
281 connected to one of 16 gameports
282 Format: <type1>,<type2>,..<type16>
285 Power management functions (SPARCstation-4/5 + deriv.)
287 Disable APC CPU standby support. SPARCstation-Fox does
288 not play well with APC CPU idle - disable it if you have
289 APC and your system crashes randomly.
291 apic= [APIC,i386] Advanced Programmable Interrupt Controller
292 Change the output verbosity whilst booting
293 Format: { quiet (default) | verbose | debug }
294 Change the amount of debugging information output
295 when initialising the APIC and IO-APIC components.
297 apm= [APM] Advanced Power Management
298 See header of arch/i386/kernel/apm.c.
303 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
304 Format: <io>,<irq>,<nodeID>
308 atarimouse= [HW,MOUSE] Atari Mouse
310 atascsi= [HW,SCSI] Atari SCSI
312 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
313 EzKey and similar keyboards
315 atkbd.reset= [HW] Reset keyboard during initialization
317 atkbd.set= [HW] Select keyboard code set
318 Format: <int> (2 = AT (default), 3 = PS/2)
320 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
323 atkbd.softraw= [HW] Choose between synthetic and real raw mode
324 Format: <bool> (0 = real, 1 = synthetic (default))
326 atkbd.softrepeat= [HW]
327 Use software keyboard repeat
331 baycom_epp= [HW,AX25]
334 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
336 See header of drivers/net/hamradio/baycom_par.c.
338 baycom_ser_fdx= [HW,AX25]
339 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
340 Format: <io>,<irq>,<mode>[,<baud>]
341 See header of drivers/net/hamradio/baycom_ser_fdx.c.
343 baycom_ser_hdx= [HW,AX25]
344 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
345 Format: <io>,<irq>,<mode>
346 See header of drivers/net/hamradio/baycom_ser_hdx.c.
348 blkmtd_device= [HW,MTD]
354 boot_delay= Milliseconds to delay each printk during boot.
355 Values larger than 10 seconds (10000) are changed to
359 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
360 bttv.radio= Most important insmod options are available as
362 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
363 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
366 See drivers/scsi/BusLogic.c, comment before function
367 BusLogic_ParseDriverOptions().
369 c101= [NET] Moxa C101 synchronous serial card
371 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
372 Sometimes CPU hardware bugs make them report the cache
373 size incorrectly. The kernel will attempt work arounds
374 to fix known problems, but for some CPUs it is not
375 possible to determine what the correct size should be.
376 This option provides an override for these situations.
379 [SECURITY] Disable capabilities. This would normally
380 be used only if an alternative security model is to be
381 configured. Potentially dangerous and should only be
382 used if you are entirely sure of the consequences.
384 chandev= [HW,NET] Generic channel device initialisation
386 checkreqprot [SELINUX] Set initial checkreqprot flag value.
387 Format: { "0" | "1" }
388 See security/selinux/Kconfig help text.
389 0 -- check protection applied by kernel (includes
390 any implied execute protection).
391 1 -- check protection requested by application.
392 Default value is set via a kernel config option.
393 Value can be changed at runtime via
394 /selinux/checkreqprot.
396 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
398 Forces specified clocksource (if available) to be used
399 when calculating gettimeofday(). If specified
400 clocksource is not available, it defaults to PIT.
401 Format: { pit | tsc | cyclone | pmtmr }
403 clocksource= [GENERIC_TIME] Override the default clocksource
405 Override the default clocksource and use the clocksource
406 with the name specified.
407 Some clocksource names to choose from, depending on
409 [all] jiffies (this is the base, fallback clocksource)
411 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
412 pxa_timer,timer3,32k_counter,timer0_1
414 [X86-32] pit,hpet,tsc,vmi-timer;
415 scx200_hrt on Geode; cyclone on IBM x440
423 code_bytes [IA32] How many bytes of object code to print in an
430 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
431 over the 8254 in addition to over the IO-APIC. The
432 kernel tries to set a sensible default.
434 hpet= [X86-32,HPET] option to disable HPET and use PIT.
437 com20020= [HW,NET] ARCnet - COM20020 chipset
439 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
441 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
445 ARCnet - COM90xx chipset (memory-mapped buffers)
446 Format: <io>[,<irq>[,<memstart>]]
448 condev= [HW,S390] console device
451 console= [KNL] Output console device and options.
453 tty<n> Use the virtual console device <n>.
457 Use the specified serial port. The options are of
458 the form "bbbbpnf", where "bbbb" is the baud rate,
459 "p" is parity ("n", "o", or "e"), "n" is number of
460 bits, and "f" is flow control ("r" for RTS or
461 omit it). Default is "9600n8".
463 See Documentation/serial-console.txt for more
465 Documentation/networking/netconsole.txt for an
468 uart[8250],io,<addr>[,options]
469 uart[8250],mmio,<addr>[,options]
470 Start an early, polled-mode console on the 8250/16550
471 UART at the specified I/O port or MMIO address,
472 switching to the matching ttyS device later. The
473 options are the same as for ttyS, above.
475 earlycon= [KNL] Output early console device and options.
476 uart[8250],io,<addr>[,options]
477 uart[8250],mmio,<addr>[,options]
478 Start an early, polled-mode console on the 8250/16550
479 UART at the specified I/O port or MMIO address.
480 The options are the same as for ttyS, above.
483 [HW] Never suspend the console
484 Disable suspending of consoles during suspend and
485 hibernate operations. Once disabled, debugging
486 messages can reach various consoles while the rest
487 of the system is being put to sleep (ie, while
488 debugging driver suspend/resume hooks). This may
489 not work reliably with all consoles, but is known
490 to work with serial and VGA consoles.
492 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
494 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
496 crashkernel=nn[KMG]@ss[KMG]
497 [KNL] Reserve a chunk of physical memory to
498 hold a kernel to switch to with kexec on panic.
500 crashkernel=range1:size1[,range2:size2,...][@offset]
501 [KNL] Same as above, but depends on the memory
502 in the running system. The syntax of range is
503 start-[end] where start and end are both
504 a memory unit (amount[KMG]). See also
505 Documentation/kdump/kdump.txt for a example.
508 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
513 cs89x0_media= [HW,NET]
514 Format: { rj45 | aui | bnc }
516 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
519 See header of drivers/s390/block/dasd_devmap.c.
521 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
522 (one device per port)
523 Format: <port#>,<type>
524 See also Documentation/input/joystick-parport.txt
526 debug [KNL] Enable kernel debugging (events log level).
529 [KNL] verbose self-tests
531 Print debugging info while doing the locking API
533 We default to 0 (no extra messages), setting it to
534 1 will print _a lot_ more information - normally
535 only useful to kernel developers.
538 Format: <area>[,<node>]
539 See also Documentation/networking/decnet.txt.
542 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
543 Change the default blue palette of the console.
544 This is a 16-member array composed of values
548 Format: <green0>,<green1>,<green2>,...,<green15>
549 Change the default green palette of the console.
550 This is a 16-member array composed of values
554 Format: <red0>,<red1>,<red2>,...,<red15>
555 Change the default red palette of the console.
556 This is a 16-member array composed of values
561 Set system-wide default UTF-8 mode for all tty's.
562 Default is 0 and by setting to 1, it enables UTF-8
563 mode for all newly opened or allocated terminals.
566 Set number of hash buckets for dentry cache.
569 IO parameters + enable/disable command.
571 digiepca= [HW,SERIAL]
572 See drivers/char/README.epca and
573 Documentation/digiepca.txt.
575 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
577 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
579 dmasound= [HW,OSS] Sound subsystem buffers
585 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
587 earlyprintk=serial[,ttySn[,baudrate]]
589 Append ",keep" to not disable it when the real console
592 Only vga or serial at a time, not both.
594 Currently only ttyS0 and ttyS1 are supported.
596 Interaction with the standard serial driver is not
599 The VGA output is eventually overwritten by the real
604 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
607 non-0: interrupt mode (default)
614 Format: {"of[f]" | "sk[ipmbr]"}
615 See comment in arch/i386/boot/edd.S
618 Format: <id>,<membase>,<irq>
620 eisa_irq_edge= [PARISC,HW]
621 See header of drivers/parisc/eisa.c.
624 See comment before function elanfreq_setup() in
625 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
628 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
629 See Documentation/block/as-iosched.txt and
630 Documentation/block/deadline-iosched.txt for details.
632 elfcorehdr= [X86-32, X86_64]
633 Specifies physical address of start of kernel core
634 image elf header. Generally kexec loader will
635 pass this option to capture kernel.
636 See Documentation/kdump/kdump.txt for details.
638 enforcing [SELINUX] Set initial enforcing status.
640 See security/selinux/Kconfig help text.
641 0 -- permissive (log only, no denials).
642 1 -- enforcing (deny and log).
644 Value can be changed at runtime via /selinux/enforce.
647 Format: <spdif>,[<nomix>,[<amplifier>]]
648 See also header of sound/oss/es1371.c.
650 ether= [HW,NET] Ethernet cards parameters
651 This option is obsoleted by the "netdev=" option, which
652 has equivalent usage. See its documentation for details.
654 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
659 fail_make_request=[KNL]
660 General fault injection mechanism.
661 Format: <interval>,<probability>,<space>,<times>
662 See also /Documentation/fault-injection/.
665 See header of drivers/scsi/fd_mcs.c.
668 See header of drivers/scsi/fdomain.c.
671 See Documentation/floppy.txt.
674 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
675 support via parallel port (up to 5 devices per port)
676 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
677 See also Documentation/input/joystick-parport.txt
682 See header of drivers/scsi/gdth.c.
684 gpt [EFI] Forces disk with valid GPT signature but
685 invalid Protective MBR to be treated as GPT.
689 hashdist= [KNL,NUMA] Large hashes allocated during boot
690 are distributed across NUMA nodes. Defaults on
691 for IA-64, off otherwise.
692 Format: 0 | 1 (for off | on)
694 hcl= [IA-64] SGI's Hardware Graph compatibility layer
696 hd= [EIDE] (E)IDE hard drive subsystem geometry
697 Format: <cyl>,<head>,<sect>
699 hd?= [HW] (E)IDE subsystem
700 hd?lun= See Documentation/ide.txt.
702 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
703 size of <nn>. This works even on boxes that have no
704 highmem otherwise. This also works to reduce highmem
705 size on bigger boxes.
707 highres= [KNL] Enable/disable high resolution timer mode.
708 Valid parameters: "on", "off"
712 See Documentation/isdn/README.HiSax.
714 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
716 i8042.direct [HW] Put keyboard port into non-translated mode
717 i8042.dumbkbd [HW] Pretend that controller can only read data from
718 keyboard and cannot control its state
719 (Don't attempt to blink the leds)
720 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
721 i8042.nokbd [HW] Don't check/create keyboard port
722 i8042.nomux [HW] Don't check presence of an active multiplexing
724 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
727 [HW] Frequency with which keyboard LEDs should blink
728 when kernel panics (default is 0.5 sec)
729 i8042.reset [HW] Reset the controller during init and cleanup
730 i8042.unlock [HW] Unlock (ignore) the keylock
734 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
735 indicates that the driver is running on unsupported
737 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
738 does not match list of supported models.
740 [HW] Report power status in /proc/i8k
741 (disabled by default)
742 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
745 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
746 See Documentation/mca.txt.
749 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
751 ide= [HW] (E)IDE subsystem
752 Format: ide=nodma or ide=doubler or ide=reverse
753 See Documentation/ide.txt.
755 ide?= [HW] (E)IDE subsystem
756 Format: ide?=noprobe or chipset specific parameters.
757 See Documentation/ide.txt.
759 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
760 See Documentation/ide.txt.
763 Format: idle=poll or idle=mwait
764 Poll forces a polling idle loop that can slightly improves the performance
765 of waking up a idle CPU, but will use a lot of power and make the system
766 run hot. Not recommended.
767 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
768 to not use it because it doesn't save as much power as a normal idle
769 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
772 ignore_loglevel [KNL]
773 Ignore loglevel setting - this will print /all/
774 kernel messages to the console. Useful for debugging.
777 Set number of hash buckets for inode cache.
780 See header of drivers/scsi/in2000.c.
784 Run specified binary instead of /sbin/init as init
787 initcall_debug [KNL] Trace initcalls as they are executed. Useful
788 for working out where the kernel is dying during
791 initrd= [BOOT] Specify the location of the initial ramdisk
793 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
798 io7= [HW] IO7 for Marvel based alpha systems
799 See comment before marvel_specify_io7 in
800 arch/alpha/kernel/core_marvel.c.
803 See Documentation/nfsroot.txt.
805 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
806 See comment before ip2_setup() in
807 drivers/char/ip2/ip2base.c.
809 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
810 See header of drivers/scsi/ips.c.
812 ports= [IP_VS_FTP] IPVS ftp helper module
814 Up to 8 (IP_VS_APP_MAX_PORTS) ports
816 Format: <port>,<port>....
819 When an interrupt is not handled search all handlers
820 for it. Intended to get systems with badly broken
824 When an interrupt is not handled search all handlers
825 for it. Also check all handlers each timer
826 interrupt. Intended to get systems with badly broken
830 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
832 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
834 <cpu number>,...,<cpu number>
836 <cpu number>-<cpu number> (must be a positive range in ascending order)
838 <cpu number>,...,<cpu number>-<cpu number>
839 This option can be used to specify one or more CPUs
840 to isolate from the general SMP balancing and scheduling
841 algorithms. The only way to move a process onto or off
842 an "isolated" CPU is via the CPU affinity syscalls.
843 <cpu number> begins at 0 and the maximum value is
844 "number of CPUs in system - 1".
846 This option is the preferred way to isolate CPUs. The
847 alternative -- manually setting the CPU mask of all
848 tasks in the system -- can cause problems and
849 suboptimal load balancer performance.
853 js= [HW,JOY] Analog joystick
854 See Documentation/input/joystick.txt.
856 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
857 specifies the amount of memory usable by the kernel
858 for non-movable allocations. The requested amount is
859 spread evenly throughout all nodes in the system. The
860 remaining memory in each node is used for Movable
861 pages. In the event, a node is too small to have both
862 kernelcore and Movable pages, kernelcore pages will
863 take priority and other nodes will have a larger number
864 of kernelcore pages. The Movable zone is used for the
865 allocation of pages that may be reclaimed or moved
866 by the page migration subsystem. This means that
867 HugeTLB pages may not be allocated from this zone.
868 Note that allocations like PTEs-from-HighMem still
869 use the HighMem zone if it exists, and the Normal
872 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
873 is similar to kernelcore except it specifies the
874 amount of memory used for migratable allocations.
875 If both kernelcore and movablecore is specified,
876 then kernelcore will be at *least* the specified
877 value but may be more. If movablecore on its own
878 is specified, the administrator must be careful
879 that the amount of memory usable for all allocations
884 kstack=N [X86-32,X86-64] Print N words from the kernel stack
889 lapic [X86-32,APIC] Enable the local APIC even if BIOS
892 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
895 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
896 Format: addr:<io>,irq:<irq>
898 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
902 load_ramdisk= [RAM] List of ramdisks to load from floppy
903 See Documentation/ramdisk.txt.
905 lockd.nlm_grace_period=P [NFS] Assign grace period.
908 lockd.nlm_tcpport=N [NFS] Assign TCP port.
911 lockd.nlm_timeout=T [NFS] Assign timeout value.
914 lockd.nlm_udpport=M [NFS] Assign UDP port.
917 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
920 loglevel= All Kernel Messages with a loglevel smaller than the
921 console loglevel will be printed to the console. It can
922 also be changed with klogd or other programs. The
923 loglevels are defined as follows:
925 0 (KERN_EMERG) system is unusable
926 1 (KERN_ALERT) action must be taken immediately
927 2 (KERN_CRIT) critical conditions
928 3 (KERN_ERR) error conditions
929 4 (KERN_WARNING) warning conditions
930 5 (KERN_NOTICE) normal but significant condition
931 6 (KERN_INFO) informational
932 7 (KERN_DEBUG) debug-level messages
934 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
935 Format: { n | nk | nM }
936 n must be a power of two. The default size
937 is set in the kernel config file.
939 logo.nologo [FB] Disables display of the built-in Linux logo.
940 This may be used to provide more screen space for
941 kernel log messages and is useful when debugging
942 kernel boot problems.
944 lp=0 [LP] Specify parallel ports to use, e.g,
945 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
946 lp=reset first parallel port). 'lp=0' disables the
947 lp=auto printer driver. 'lp=reset' (which can be
948 specified in addition to the ports) causes
949 attached printers to be reset. Using
950 lp=port1,port2,... specifies the parallel ports
951 to associate lp devices with, starting with
952 lp0. A port specification may be 'none' to skip
953 that lp device, or a parport name such as
954 'parport0'. Specifying 'lp=auto' instead of a
955 port specification list means that device IDs
956 from each port should be examined, to see if
957 an IEEE 1284-compliant printer is attached; if
958 so, the driver will manage that printer.
959 See also header of drivers/char/lp.c.
962 Sets loops_per_jiffy to given constant, thus avoiding
963 time-consuming boot-time autodetection (up to 250 ms per
964 CPU). 0 enables autodetection (default). To determine
965 the correct value for your kernel, boot with normal
966 autodetection and see what value is printed. Note that
967 on SMP systems the preset will be applied to all CPUs,
968 which is likely to cause problems if your CPUs need
969 significantly divergent settings. An incorrect value
970 will cause delays in the kernel to be wrong, leading to
971 unpredictable I/O errors and other breakage. Although
972 unlikely, in the extreme case this might damage your
976 Format: <io>,<irq>,<dma>
978 mac5380= [HW,SCSI] Format:
979 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
981 mac53c9x= [HW,SCSI] Format:
982 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
984 machvec= [IA64] Force the use of a particular machine-vector
985 (machvec) in a generic kernel.
986 Example: machvec=hpzx1_swiotlb
988 max_loop= [LOOP] Maximum number of loopback devices that can
992 maxcpus= [SMP] Maximum number of processors that an SMP kernel
993 should make use of. maxcpus=n : n >= 0 limits the
994 kernel to using 'n' processors. n=0 is a special case,
995 it is equivalent to "nosmp", which also disables
998 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
999 equal to this physical address is ignored.
1001 max_luns= [SCSI] Maximum number of LUNs to probe.
1002 Should be between 1 and 2^32-1.
1005 [SCSI] Maximum number of LUNs received.
1006 Should be between 1 and 16384.
1008 mca-pentium [BUGS=X86-32]
1012 mce [X86-32] Machine Check Exception
1014 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1016 md= [HW] RAID subsystems devices and level
1017 See Documentation/md.txt.
1020 Format: <first>,<last>
1021 Specifies range of consoles to be captured by the MDA.
1023 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1024 Amount of memory to be used when the kernel is not able
1025 to see the whole system memory or for test.
1026 [X86-32] Use together with memmap= to avoid physical
1027 address space collisions. Without memmap= PCI devices
1028 could be placed at addresses belonging to unused RAM.
1030 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1033 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1034 E820 memory map, as specified by the user.
1035 Such memmap=exactmap lines can be constructed based on
1036 BIOS output or other requirements. See the memmap=nn@ss
1039 memmap=nn[KMG]@ss[KMG]
1040 [KNL] Force usage of a specific region of memory
1041 Region of memory to be used, from ss to ss+nn.
1043 memmap=nn[KMG]#ss[KMG]
1044 [KNL,ACPI] Mark specific memory as ACPI data.
1045 Region of memory to be used, from ss to ss+nn.
1047 memmap=nn[KMG]$ss[KMG]
1048 [KNL,ACPI] Mark specific memory as reserved.
1049 Region of memory to be used, from ss to ss+nn.
1051 meye.*= [HW] Set MotionEye Camera parameters
1052 See Documentation/video4linux/meye.txt.
1054 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1055 Multi-Function General Purpose Timers on AMD Geode
1061 [MOUSE] Maximum time between finger touching and
1062 leaving touchpad surface for touch to be considered
1063 a tap and be reported as a left button click (for
1064 touchpads working in absolute mode only).
1066 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1067 reporting absolute coordinates, such as tablets
1068 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1069 reporting absolute coordinates, such as tablets
1074 MTD_Partition= [MTD]
1075 Format: <name>,<region-number>,<size>,<offset>
1077 MTD_Region= [MTD] Format:
1078 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1081 See drivers/mtd/cmdlinepart.c.
1083 mtouchusb.raw_coordinates=
1084 [HW] Make the MicroTouch USB driver use raw coordinates
1085 ('y', default) or cooked coordinates ('n')
1087 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1090 See header of drivers/scsi/NCR_D700.c.
1094 ncr53c400= [HW,SCSI]
1096 ncr53c400a= [HW,SCSI]
1098 ncr53c406a= [HW,SCSI]
1100 ncr53c8xx= [HW,SCSI]
1102 netdev= [NET] Network devices parameters
1103 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1104 Note that mem_start is often overloaded to mean
1105 something different and driver-specific.
1106 This usage is only documented in each driver source
1110 See Documentation/nfsroot.txt.
1112 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1113 See Documentation/nfsroot.txt.
1115 nfs.callback_tcpport=
1116 [NFS] set the TCP port on which the NFSv4 callback
1117 channel should listen.
1119 nfs.idmap_cache_timeout=
1120 [NFS] set the maximum lifetime for idmapper cache
1124 [NFS] enable 64-bit inode numbers.
1125 If zero, the NFS client will fake up a 32-bit inode
1126 number for the readdir() and stat() syscalls instead
1127 of returning the full 64-bit number.
1128 The default is to return 64-bit inode numbers.
1130 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1132 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1133 emulation library even if a 387 maths coprocessor
1136 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1137 caches in the slab allocator. Saves per-node memory,
1138 but will impact performance.
1142 noapic [SMP,APIC] Tells the kernel to not make use of any
1143 IOAPICs that may be present in the system.
1145 noasync [HW,M68K] Disables async and sync negotiation for
1148 nobats [PPC] Do not use BATs for mapping kernel lowmem
1149 on "Classic" PPC cores.
1153 nodelayacct [KNL] Disable per-task delay accounting
1155 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1159 noexec [X86-32,X86-64]
1160 noexec=on: enable non-executable mappings (default)
1161 noexec=off: disable nn-executable mappings
1163 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1164 register save and restore. The kernel will only save
1165 legacy floating-point registers on task switch.
1169 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1170 instruction doesn't work correctly and not to
1173 nohalt [IA-64] Tells the kernel not to use the power saving
1174 function PAL_HALT_LIGHT when idle. This increases
1175 power-consumption. On the positive side, it reduces
1176 interrupt wake-up latency, which may improve performance
1177 in certain environments such as networked servers or
1180 nohz= [KNL] Boottime enable/disable dynamic ticks
1181 Valid arguments: on, off
1184 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1186 noirqdebug [X86-32] Disables the code which attempts to detect and
1187 disable unhandled interrupt sources.
1189 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1190 broken timer IRQ sources.
1192 noisapnp [ISAPNP] Disables ISA PnP code.
1194 noinitrd [RAM] Tells the kernel not to load any configured
1199 nojitter [IA64] Disables jitter checking for ITC timers.
1201 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1203 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1205 noltlbs [PPC] Do not use large page/tlb entries for kernel
1206 lowmem mapping on PPC40x.
1208 nomca [IA-64] Disable machine check abort handling
1210 nomce [X86-32] Machine Check Exception
1212 nomfgpt [X86-32] Disable Multi-Function General Purpose
1213 Timer usage (for AMD Geode machines).
1215 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1217 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1218 with UP alternatives
1220 noresidual [PPC] Don't use residual data on PReP machines.
1222 noresume [SWSUSP] Disables resume and restores original swap
1225 no-scroll [VGA] Disables scrollback.
1226 This is required for the Braillex ib80-piezo Braille
1227 reader made by F.H. Papenmeier (Germany).
1231 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1233 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1234 and disable the IO APIC. legacy for "maxcpus=0".
1236 nosoftlockup [KNL] Disable the soft-lockup detector.
1238 nosync [HW,M68K] Disables sync negotiation for all devices.
1240 notsc [BUGS=X86-32] Disable Time Stamp Counter
1242 nousb [USB] Disable the USB subsystem
1246 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1247 one of ['zone', 'node', 'default'] can be specified
1248 This can be set from sysctl after boot.
1249 See Documentation/sysctl/vm.txt for details.
1251 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1256 oprofile.timer= [HW]
1257 Use timer interrupt instead of performance counters
1259 osst= [HW,SCSI] SCSI Tape Driver
1260 Format: <buffer_size>,<write_threshold>
1261 See also Documentation/scsi/st.txt.
1263 panic= [KNL] Kernel behaviour on panic
1266 parkbd.port= [HW] Parallel port number the keyboard adapter is
1267 connected to, default is 0.
1269 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1270 0 for XT, 1 for AT (default is AT).
1273 parport= [HW,PPT] Specify parallel ports. 0 disables.
1274 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1275 Use 'auto' to force the driver to use any
1276 IRQ/DMA settings detected (the default is to
1277 ignore detected IRQ/DMA settings because of
1278 possible conflicts). You can specify the base
1279 address, IRQ, and DMA settings; IRQ and DMA
1280 should be numbers, or 'auto' (for using detected
1281 settings on that particular port), or 'nofifo'
1282 (to avoid using a FIFO even if it is detected).
1283 Parallel ports are assigned in the order they
1284 are specified on the command line, starting
1287 parport_init_mode= [HW,PPT]
1288 Configure VIA parallel port to operate in
1289 a specific mode. This is necessary on Pegasos
1290 computer where firmware has no options for setting
1291 up parallel port mode and sets it to spp.
1292 Currently this function knows 686a and 8231 chips.
1293 Format: [spp|ps2|epp|ecp|ecpepp]
1295 pas2= [HW,OSS] Format:
1296 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1299 See header of drivers/scsi/pas16.c.
1302 Halt all CPUs after the first oops has been printed for
1303 the specified number of seconds. This is to be used if
1304 your oopses keep scrolling off the screen.
1309 See header of drivers/block/paride/pcd.c.
1310 See also Documentation/paride.txt.
1312 pci=option[,option...] [PCI] various PCI subsystem options:
1313 off [X86-32] don't probe for the PCI bus
1314 bios [X86-32] force use of PCI BIOS, don't access
1315 the hardware directly. Use this if your machine
1316 has a non-standard PCI host bridge.
1317 nobios [X86-32] disallow use of PCI BIOS, only direct
1318 hardware access methods are allowed. Use this
1319 if you experience crashes upon bootup and you
1320 suspect they are caused by the BIOS.
1321 conf1 [X86-32] Force use of PCI Configuration
1323 conf2 [X86-32] Force use of PCI Configuration
1325 noaer [PCIE] If the PCIEAER kernel config parameter is
1326 enabled, this kernel boot option can be used to
1327 disable the use of PCIE advanced error reporting.
1328 nodomains [PCI] Disable support for multiple PCI
1329 root domains (aka PCI segments, in ACPI-speak).
1330 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1332 nomsi [MSI] If the PCI_MSI kernel config parameter is
1333 enabled, this kernel boot option can be used to
1334 disable the use of MSI interrupts system-wide.
1335 nosort [X86-32] Don't sort PCI devices according to
1336 order given by the PCI BIOS. This sorting is
1337 done to get a device order compatible with
1339 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1340 routing table. These calls are known to be buggy
1341 on several machines and they hang the machine
1342 when used, but on other computers it's the only
1343 way to get the interrupt routing table. Try
1344 this option if the kernel is unable to allocate
1345 IRQs or discover secondary PCI buses on your
1347 rom [X86-32] Assign address space to expansion ROMs.
1348 Use with caution as certain devices share
1349 address decoders between ROMs and other
1351 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1352 assigned automatically to PCI devices. You can
1353 make the kernel exclude IRQs of your ISA cards
1355 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1356 of the PIRQ table (normally generated
1357 by the BIOS) if it is outside the
1358 F0000h-100000h range.
1359 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1360 useful if the kernel is unable to find your
1361 secondary buses and you want to tell it
1362 explicitly which ones they are.
1363 assign-busses [X86-32] Always assign all PCI bus
1364 numbers ourselves, overriding
1365 whatever the firmware may have done.
1366 usepirqmask [X86-32] Honor the possible IRQ mask stored
1367 in the BIOS $PIR table. This is needed on
1368 some systems with broken BIOSes, notably
1369 some HP Pavilion N5400 and Omnibook XE3
1370 notebooks. This will have no effect if ACPI
1371 IRQ routing is enabled.
1372 noacpi [X86-32] Do not use ACPI for IRQ routing
1373 or for PCI scanning.
1374 use_crs [X86-32] Use _CRS for PCI resource
1376 routeirq Do IRQ routing for all PCI devices.
1377 This is normally done in pci_enable_device(),
1378 so this option is a temporary workaround
1379 for broken drivers that don't call it.
1380 firmware [ARM] Do not re-enumerate the bus but instead
1381 just use the configuration from the
1382 bootloader. This is currently used on
1383 IXP2000 systems where the bus has to be
1384 configured a certain way for adjunct CPUs.
1385 noearly [X86] Don't do any early type 1 scanning.
1386 This might help on some broken boards which
1387 machine check when some devices' config space
1388 is read. But various workarounds are disabled
1389 and some IOMMU drivers will not work.
1390 bfsort Sort PCI devices into breadth-first order.
1391 This sorting is done to get a device
1392 order compatible with older (<= 2.4) kernels.
1393 nobfsort Don't sort PCI devices into breadth-first order.
1394 cbiosize=nn[KMG] The fixed amount of bus space which is
1395 reserved for the CardBus bridge's IO window.
1396 The default value is 256 bytes.
1397 cbmemsize=nn[KMG] The fixed amount of bus space which is
1398 reserved for the CardBus bridge's memory
1399 window. The default value is 64 megabytes.
1401 pcmv= [HW,PCMCIA] BadgePAD 4
1404 See Documentation/paride.txt.
1406 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1409 See arch/parisc/kernel/pdc_chassis.c
1412 See Documentation/paride.txt.
1415 See Documentation/paride.txt.
1417 pirq= [SMP,APIC] Manual mp-table setup
1418 See Documentation/i386/IO-APIC.txt.
1420 plip= [PPT,NET] Parallel port network link
1421 Format: { parport<nr> | timid | 0 }
1422 See also Documentation/parport.txt.
1428 { on | off | curr | res | no-curr | no-res }
1431 [ISAPNP] Exclude IRQs for the autoconfiguration
1434 [ISAPNP] Exclude DMAs for the autoconfiguration
1436 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1437 Ranges are in pairs (I/O port base and size).
1440 [ISAPNP] Exclude memory regions for the
1442 Ranges are in pairs (memory base and size).
1444 print-fatal-signals=
1445 [KNL] debug: print fatal signals
1446 print-fatal-signals=1: print segfault info to
1450 printk.time= Show timing data prefixed to each printk message line
1451 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1453 profile= [KNL] Enable kernel profiling via /proc/profile
1454 Format: [schedule,]<number>
1455 Param: "schedule" - profile schedule points.
1456 Param: <number> - step/bucket size as a power of 2 for
1457 statistical time based profiling.
1458 Param: "sleep" - profile D-state sleeping (millisecs)
1460 processor.max_cstate= [HW,ACPI]
1461 Limit processor to maximum C-state
1462 max_cstate=9 overrides any DMI blacklist limit.
1464 processor.nocst [HW,ACPI]
1465 Ignore the _CST method to determine C-states,
1466 instead using the legacy FADT method
1468 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1470 See Documentation/ramdisk.txt.
1472 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1473 probe for; one of (bare|imps|exps|lifebook|any).
1474 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1476 psmouse.resetafter= [HW,MOUSE]
1477 Try to reset the device after so many bad packets
1480 [HW,MOUSE] Set desired mouse resolution, in dpi.
1481 psmouse.smartscroll=
1482 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1483 0 = disabled, 1 = enabled (default).
1485 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1487 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1490 See Documentation/paride.txt.
1493 [KNL] Number of legacy pty's. Overwrites compiled-in
1496 quiet [KNL] Disable most log messages
1501 See Documentation/md.txt.
1503 ramdisk_blocksize= [RAM]
1504 See Documentation/ramdisk.txt.
1506 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1507 See Documentation/ramdisk.txt.
1509 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1510 RCU callbacks to process in one batch.
1512 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1513 RCU callbacks over which batch limiting is disabled.
1515 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1516 RCU callbacks below which batch limiting is re-enabled.
1520 Run specified binary instead of /init from the ramdisk,
1521 used for early userspace startup. See initrd.
1523 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1524 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1525 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1527 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1529 reservetop= [X86-32]
1531 Reserves a hole at the top of the kernel virtual
1534 reset_devices [KNL] Force drivers to reset the underlying device
1535 during initialization.
1538 Specify the partition device for software suspend
1540 resume_offset= [SWSUSP]
1541 Specify the offset from the beginning of the partition
1542 given by "resume=" at which the swap header is located,
1543 in <PAGE_SIZE> units (needed only for swap files).
1544 See Documentation/power/swsusp-and-swap-files.txt
1546 retain_initrd [RAM] Keep initrd memory after extraction
1548 rhash_entries= [KNL,NET]
1549 Set number of hash buckets for route cache
1551 riscom8= [HW,SERIAL]
1552 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1554 ro [KNL] Mount root device read-only on boot
1556 root= [KNL] Root filesystem
1558 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1559 mount the root filesystem
1561 rootflags= [KNL] Set root filesystem mount option string
1563 rootfstype= [KNL] Set root filesystem type
1565 rootwait [KNL] Wait (indefinitely) for root device to show up.
1566 Useful for devices that are detected asynchronously
1567 (e.g. USB and MMC devices).
1569 root_plug.vendor_id=
1570 [ROOTPLUG] Override the default vendor ID
1572 root_plug.product_id=
1573 [ROOTPLUG] Override the default product ID
1576 [ROOTPLUG] Enable debugging output
1578 rw [KNL] Mount root device read-write on boot
1580 S [KNL] Run init in single mode
1583 See drivers/net/irda/sa1100_ir.c.
1586 Format: <io>,<irq>,<dma>,<dma2>
1588 sbni= [NET] Granch SBNI12 leased line adapter
1590 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1591 Format: <io>[,<timeout>[,<isapnp>]]
1593 scsi_debug_*= [SCSI]
1594 See drivers/scsi/scsi_debug.c.
1596 scsi_default_dev_flags=
1597 [SCSI] SCSI default device flags
1600 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1601 Format: <vendor>:<model>:<flags>
1602 (flags are integer value)
1604 scsi_logging= [SCSI]
1606 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1607 discovered. async scans them in kernel threads,
1608 allowing boot to proceed. none ignores them, expecting
1609 user space to do the scan.
1611 selinux [SELINUX] Disable or enable SELinux at boot time.
1612 Format: { "0" | "1" }
1613 See security/selinux/Kconfig help text.
1616 Default value is set via kernel config option.
1617 If enabled at boot time, /selinux/disable can be used
1618 later to disable prior to initial policy load.
1620 selinux_compat_net =
1621 [SELINUX] Set initial selinux_compat_net flag value.
1622 Format: { "0" | "1" }
1623 0 -- use new secmark-based packet controls
1624 1 -- use legacy packet controls
1625 Default value is 0 (preferred).
1626 Value can be changed at runtime via
1627 /selinux/compat_net.
1629 serialnumber [BUGS=X86-32]
1631 sg_def_reserved_size= [SCSI]
1634 Maximal number of shapers.
1637 See header of drivers/scsi/sim710.c.
1644 slub_debug[=options[,slabs]] [MM, SLUB]
1645 Enabling slub_debug allows one to determine the
1646 culprit if slab objects become corrupted. Enabling
1647 slub_debug can create guard zones around objects and
1648 may poison objects when not in use. Also tracks the
1649 last alloc / free. For more information see
1650 Documentation/vm/slub.txt.
1652 slub_max_order= [MM, SLUB]
1653 Determines the maximum allowed order for slabs.
1654 A high setting may cause OOMs due to memory
1655 fragmentation. For more information see
1656 Documentation/vm/slub.txt.
1658 slub_min_objects= [MM, SLUB]
1659 The minimum number of objects per slab. SLUB will
1660 increase the slab order up to slub_max_order to
1661 generate a sufficiently large slab able to contain
1662 the number of objects indicated. The higher the number
1663 of objects the smaller the overhead of tracking slabs
1664 and the less frequently locks need to be acquired.
1665 For more information see Documentation/vm/slub.txt.
1667 slub_min_order= [MM, SLUB]
1668 Determines the mininum page order for slabs. Must be
1669 lower than slub_max_order.
1670 For more information see Documentation/vm/slub.txt.
1672 slub_nomerge [MM, SLUB]
1673 Disable merging of slabs with similar size. May be
1674 necessary if there is some reason to distinguish
1675 allocs to different slabs. Debug options disable
1676 merging on their own.
1677 For more information see Documentation/vm/slub.txt.
1680 Format: <io1>[,<io2>[,...,<io8>]]
1682 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1683 attempt to substitute SMP alternatives once at boot.
1685 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1686 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1687 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1688 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1689 smsc-ircc2.ircc_irq= [HW] IRQ line
1690 smsc-ircc2.ircc_dma= [HW] DMA channel
1691 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1692 0: Toshiba Satellite 1800 (GP data pin select)
1693 1: Fast pin select (default)
1696 snd-ad1816a= [HW,ALSA]
1698 snd-ad1848= [HW,ALSA]
1700 snd-ali5451= [HW,ALSA]
1702 snd-als100= [HW,ALSA]
1704 snd-als4000= [HW,ALSA]
1706 snd-azt2320= [HW,ALSA]
1708 snd-cmi8330= [HW,ALSA]
1710 snd-cmipci= [HW,ALSA]
1712 snd-cs4231= [HW,ALSA]
1714 snd-cs4232= [HW,ALSA]
1716 snd-cs4236= [HW,ALSA]
1718 snd-cs4281= [HW,ALSA]
1720 snd-cs46xx= [HW,ALSA]
1722 snd-dt019x= [HW,ALSA]
1724 snd-dummy= [HW,ALSA]
1726 snd-emu10k1= [HW,ALSA]
1728 snd-ens1370= [HW,ALSA]
1730 snd-ens1371= [HW,ALSA]
1732 snd-es968= [HW,ALSA]
1734 snd-es1688= [HW,ALSA]
1736 snd-es18xx= [HW,ALSA]
1738 snd-es1938= [HW,ALSA]
1740 snd-es1968= [HW,ALSA]
1742 snd-fm801= [HW,ALSA]
1744 snd-gusclassic= [HW,ALSA]
1746 snd-gusextreme= [HW,ALSA]
1748 snd-gusmax= [HW,ALSA]
1752 snd-ice1712= [HW,ALSA]
1754 snd-intel8x0= [HW,ALSA]
1756 snd-interwave= [HW,ALSA]
1761 snd-korg1212= [HW,ALSA]
1763 snd-maestro3= [HW,ALSA]
1765 snd-mpu401= [HW,ALSA]
1767 snd-mtpav= [HW,ALSA]
1769 snd-nm256= [HW,ALSA]
1771 snd-opl3sa2= [HW,ALSA]
1779 snd-opti93x= [HW,ALSA]
1783 snd-rme32= [HW,ALSA]
1785 snd-rme96= [HW,ALSA]
1787 snd-rme9652= [HW,ALSA]
1793 snd-sbawe= [HW,ALSA]
1795 snd-serial= [HW,ALSA]
1797 snd-sgalaxy= [HW,ALSA]
1799 snd-sonicvibes= [HW,ALSA]
1804 snd-sun-cs4231= [HW,ALSA]
1806 snd-trident= [HW,ALSA]
1808 snd-usb-audio= [HW,ALSA,USB]
1810 snd-via82xx= [HW,ALSA]
1812 snd-virmidi= [HW,ALSA]
1814 snd-wavefront= [HW,ALSA]
1816 snd-ymfpci= [HW,ALSA]
1818 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1819 See Documentation/sonypi.txt
1821 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1822 See Documentation/specialix.txt.
1824 spia_io_base= [HW,MTD]
1830 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1832 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1833 See Documentation/scsi/st.txt.
1836 See header of drivers/scsi/seagate.c.
1840 Set the STI (builtin display/keyboard on the HP-PARISC
1841 machines) console (graphic card) which should be used
1842 as the initial boot-console.
1843 See also comment in drivers/video/console/sticore.c.
1846 See comment in drivers/video/console/sticore.c.
1849 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1853 Control how the NFS server code allocates CPUs to
1854 service thread pools. Depending on how many NICs
1855 you have and where their interrupts are bound, this
1856 option will affect which CPUs will do NFS serving.
1857 Note: this parameter cannot be changed while the
1858 NFS server is running.
1860 auto the server chooses an appropriate mode
1861 automatically using heuristics
1862 global a single global pool contains all CPUs
1863 percpu one pool for each CPU
1864 pernode one pool for each NUMA node (equivalent
1865 to global on non-NUMA machines)
1867 swiotlb= [IA-64] Number of I/O TLB slabs
1871 sym53c416= [HW,SCSI]
1872 See header of drivers/scsi/sym53c416.c.
1874 sysrq_always_enabled
1876 Ignore sysrq setting - this boot parameter will
1877 neutralize any effect of /proc/sys/kernel/sysrq.
1878 Useful for debugging.
1881 See header of drivers/scsi/t128.c.
1885 thash_entries= [KNL,NET]
1886 Set number of hash buckets for TCP connection
1888 thermal.act= [HW,ACPI]
1889 -1: disable all active trip points in all thermal zones
1890 <degrees C>: override all lowest active trip points
1892 thermal.crt= [HW,ACPI]
1893 -1: disable all critical trip points in all thermal zones
1894 <degrees C>: lower all critical trip points
1896 thermal.nocrt= [HW,ACPI]
1897 Set to disable actions on ACPI thermal zone
1898 critical and hot trip points.
1900 thermal.off= [HW,ACPI]
1901 1: disable ACPI thermal control
1903 thermal.psv= [HW,ACPI]
1904 -1: disable all passive trip points
1905 <degrees C>: override all passive trip points to this value
1907 thermal.tzp= [HW,ACPI]
1908 Specify global default ACPI thermal zone polling rate
1909 <deci-seconds>: poll all this frequency
1910 0: no polling (default)
1912 time Show timing data prefixed to each printk message line
1913 [deprecated, see 'printk.time']
1915 tipar.timeout= [HW,PPT]
1916 Set communications timeout in tenths of a second
1919 tipar.delay= [HW,PPT]
1920 Set inter-bit delay in microseconds (default 10).
1923 See header of drivers/scsi/seagate.c.
1926 See comment before function dc390_setup() in
1927 drivers/scsi/tmscsim.c.
1931 trix= [HW,OSS] MediaTrix AudioTrix Pro
1933 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1935 turbografx.map[2|3]= [HW,JOY]
1936 TurboGraFX parallel port interface
1938 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1939 See also Documentation/input/joystick-parport.txt
1941 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1942 See header of drivers/scsi/u14-34f.c.
1951 [USB] Ignore overcurrent events (default N).
1952 Some badly-designed motherboards generate lots of
1953 bogus events, for ports that aren't wired to
1954 anything. Set this parameter to avoid log spamming.
1955 Note that genuine overcurrent events won't be
1958 usbcore.autosuspend=
1959 [USB] The autosuspend time delay (in seconds) used
1960 for newly-detected USB devices (default 2). This
1961 is the time required before an idle device will be
1962 autosuspended. Devices for which the delay is set
1963 to a negative value won't be autosuspended at all.
1966 [USBHID] The interval which mice are to be polled at.
1968 vdso= [X86-32,SH,x86-64]
1969 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1970 vdso=1: enable VDSO (default)
1971 vdso=0: disable VDSO mapping
1974 vector=percpu: enable percpu vector domain
1976 video= [FB] Frame buffer configuration
1977 See Documentation/fb/modedb.txt.
1979 vga= [BOOT,X86-32] Select a particular video mode
1980 See Documentation/i386/boot.txt and
1981 Documentation/svga.txt.
1982 Use vga=ask for menu.
1983 This is actually a boot loader parameter; the value is
1984 passed to the kernel using a special protocol.
1986 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1987 size of <nn>. This can be used to increase the
1988 minimum size (128MB on x86). It can also be used to
1989 decrease the size and leave more room for directly
1992 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1995 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1998 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2001 waveartist= [HW,OSS]
2002 Format: <io>,<irq>,<dma>,<dma2>
2005 See header of drivers/scsi/wd33c93.c.
2008 See header of drivers/scsi/wd7000.c.
2011 See Documentation/watchdog/wdt.txt.
2013 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2014 xd_geo= See header of drivers/block/xd.c.
2016 xirc2ps_cs= [NET,PCMCIA]
2018 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2020 norandmaps Don't use address space randomization
2021 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2023 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
2024 This is useful to get more information why
2025 you got a "dwarf2 unwinder stuck"
2027 ______________________________________________________________________
2031 Add documentation for ALSA options.
2032 Add more DRM drivers.