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 control HPET usage
435 Format: { enable (default) | disable | force }
436 disable: disable HPET and use PIT instead
437 force: allow force enabled of undocumented chips (ICH4, VIA)
439 com20020= [HW,NET] ARCnet - COM20020 chipset
441 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
443 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
447 ARCnet - COM90xx chipset (memory-mapped buffers)
448 Format: <io>[,<irq>[,<memstart>]]
450 condev= [HW,S390] console device
453 console= [KNL] Output console device and options.
455 tty<n> Use the virtual console device <n>.
459 Use the specified serial port. The options are of
460 the form "bbbbpnf", where "bbbb" is the baud rate,
461 "p" is parity ("n", "o", or "e"), "n" is number of
462 bits, and "f" is flow control ("r" for RTS or
463 omit it). Default is "9600n8".
465 See Documentation/serial-console.txt for more
467 Documentation/networking/netconsole.txt for an
470 uart[8250],io,<addr>[,options]
471 uart[8250],mmio,<addr>[,options]
472 Start an early, polled-mode console on the 8250/16550
473 UART at the specified I/O port or MMIO address,
474 switching to the matching ttyS device later. The
475 options are the same as for ttyS, above.
477 earlycon= [KNL] Output early console device and options.
478 uart[8250],io,<addr>[,options]
479 uart[8250],mmio,<addr>[,options]
480 Start an early, polled-mode console on the 8250/16550
481 UART at the specified I/O port or MMIO address.
482 The options are the same as for ttyS, above.
485 [HW] Never suspend the console
486 Disable suspending of consoles during suspend and
487 hibernate operations. Once disabled, debugging
488 messages can reach various consoles while the rest
489 of the system is being put to sleep (ie, while
490 debugging driver suspend/resume hooks). This may
491 not work reliably with all consoles, but is known
492 to work with serial and VGA consoles.
494 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
496 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
498 crashkernel=nn[KMG]@ss[KMG]
499 [KNL] Reserve a chunk of physical memory to
500 hold a kernel to switch to with kexec on panic.
503 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
508 cs89x0_media= [HW,NET]
509 Format: { rj45 | aui | bnc }
511 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
514 See header of drivers/s390/block/dasd_devmap.c.
516 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
517 (one device per port)
518 Format: <port#>,<type>
519 See also Documentation/input/joystick-parport.txt
521 debug [KNL] Enable kernel debugging (events log level).
524 [KNL] verbose self-tests
526 Print debugging info while doing the locking API
528 We default to 0 (no extra messages), setting it to
529 1 will print _a lot_ more information - normally
530 only useful to kernel developers.
533 Format: <area>[,<node>]
534 See also Documentation/networking/decnet.txt.
537 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
538 Change the default blue palette of the console.
539 This is a 16-member array composed of values
543 Format: <green0>,<green1>,<green2>,...,<green15>
544 Change the default green palette of the console.
545 This is a 16-member array composed of values
549 Format: <red0>,<red1>,<red2>,...,<red15>
550 Change the default red palette of the console.
551 This is a 16-member array composed of values
556 Set system-wide default UTF-8 mode for all tty's.
557 Default is 0 and by setting to 1, it enables UTF-8
558 mode for all newly opened or allocated terminals.
561 Set number of hash buckets for dentry cache.
564 IO parameters + enable/disable command.
566 digiepca= [HW,SERIAL]
567 See drivers/char/README.epca and
568 Documentation/digiepca.txt.
570 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
572 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
574 dmasound= [HW,OSS] Sound subsystem buffers
580 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
582 earlyprintk=serial[,ttySn[,baudrate]]
584 Append ",keep" to not disable it when the real console
587 Only vga or serial at a time, not both.
589 Currently only ttyS0 and ttyS1 are supported.
591 Interaction with the standard serial driver is not
594 The VGA output is eventually overwritten by the real
599 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
602 non-0: interrupt mode (default)
609 Format: {"of[f]" | "sk[ipmbr]"}
610 See comment in arch/i386/boot/edd.S
613 Format: <id>,<membase>,<irq>
615 eisa_irq_edge= [PARISC,HW]
616 See header of drivers/parisc/eisa.c.
619 See comment before function elanfreq_setup() in
620 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
623 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
624 See Documentation/block/as-iosched.txt and
625 Documentation/block/deadline-iosched.txt for details.
627 elfcorehdr= [X86-32, X86_64]
628 Specifies physical address of start of kernel core
629 image elf header. Generally kexec loader will
630 pass this option to capture kernel.
631 See Documentation/kdump/kdump.txt for details.
633 enforcing [SELINUX] Set initial enforcing status.
635 See security/selinux/Kconfig help text.
636 0 -- permissive (log only, no denials).
637 1 -- enforcing (deny and log).
639 Value can be changed at runtime via /selinux/enforce.
642 Format: <spdif>,[<nomix>,[<amplifier>]]
643 See also header of sound/oss/es1371.c.
645 ether= [HW,NET] Ethernet cards parameters
646 This option is obsoleted by the "netdev=" option, which
647 has equivalent usage. See its documentation for details.
649 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
654 fail_make_request=[KNL]
655 General fault injection mechanism.
656 Format: <interval>,<probability>,<space>,<times>
657 See also /Documentation/fault-injection/.
660 See header of drivers/scsi/fd_mcs.c.
663 See header of drivers/scsi/fdomain.c.
666 See Documentation/floppy.txt.
669 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
670 support via parallel port (up to 5 devices per port)
671 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
672 See also Documentation/input/joystick-parport.txt
677 See header of drivers/scsi/gdth.c.
679 gpt [EFI] Forces disk with valid GPT signature but
680 invalid Protective MBR to be treated as GPT.
684 hashdist= [KNL,NUMA] Large hashes allocated during boot
685 are distributed across NUMA nodes. Defaults on
686 for IA-64, off otherwise.
687 Format: 0 | 1 (for off | on)
689 hcl= [IA-64] SGI's Hardware Graph compatibility layer
691 hd= [EIDE] (E)IDE hard drive subsystem geometry
692 Format: <cyl>,<head>,<sect>
694 hd?= [HW] (E)IDE subsystem
695 hd?lun= See Documentation/ide.txt.
697 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
698 size of <nn>. This works even on boxes that have no
699 highmem otherwise. This also works to reduce highmem
700 size on bigger boxes.
702 highres= [KNL] Enable/disable high resolution timer mode.
703 Valid parameters: "on", "off"
707 See Documentation/isdn/README.HiSax.
709 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
711 i8042.direct [HW] Put keyboard port into non-translated mode
712 i8042.dumbkbd [HW] Pretend that controller can only read data from
713 keyboard and cannot control its state
714 (Don't attempt to blink the leds)
715 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
716 i8042.nokbd [HW] Don't check/create keyboard port
717 i8042.nomux [HW] Don't check presence of an active multiplexing
719 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
722 [HW] Frequency with which keyboard LEDs should blink
723 when kernel panics (default is 0.5 sec)
724 i8042.reset [HW] Reset the controller during init and cleanup
725 i8042.unlock [HW] Unlock (ignore) the keylock
729 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
730 indicates that the driver is running on unsupported
732 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
733 does not match list of supported models.
735 [HW] Report power status in /proc/i8k
736 (disabled by default)
737 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
740 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
741 See Documentation/mca.txt.
744 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
746 ide= [HW] (E)IDE subsystem
747 Format: ide=nodma or ide=doubler or ide=reverse
748 See Documentation/ide.txt.
750 ide?= [HW] (E)IDE subsystem
751 Format: ide?=noprobe or chipset specific parameters.
752 See Documentation/ide.txt.
754 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
755 See Documentation/ide.txt.
758 Format: idle=poll or idle=mwait
759 Poll forces a polling idle loop that can slightly improves the performance
760 of waking up a idle CPU, but will use a lot of power and make the system
761 run hot. Not recommended.
762 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
763 to not use it because it doesn't save as much power as a normal idle
764 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
767 ignore_loglevel [KNL]
768 Ignore loglevel setting - this will print /all/
769 kernel messages to the console. Useful for debugging.
772 Set number of hash buckets for inode cache.
775 See header of drivers/scsi/in2000.c.
779 Run specified binary instead of /sbin/init as init
782 initcall_debug [KNL] Trace initcalls as they are executed. Useful
783 for working out where the kernel is dying during
786 initrd= [BOOT] Specify the location of the initial ramdisk
788 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
793 io7= [HW] IO7 for Marvel based alpha systems
794 See comment before marvel_specify_io7 in
795 arch/alpha/kernel/core_marvel.c.
798 See Documentation/nfsroot.txt.
800 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
801 See comment before ip2_setup() in
802 drivers/char/ip2/ip2base.c.
804 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
805 See header of drivers/scsi/ips.c.
807 ports= [IP_VS_FTP] IPVS ftp helper module
809 Up to 8 (IP_VS_APP_MAX_PORTS) ports
811 Format: <port>,<port>....
814 When an interrupt is not handled search all handlers
815 for it. Intended to get systems with badly broken
819 When an interrupt is not handled search all handlers
820 for it. Also check all handlers each timer
821 interrupt. Intended to get systems with badly broken
825 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
827 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
829 <cpu number>,...,<cpu number>
831 <cpu number>-<cpu number> (must be a positive range in ascending order)
833 <cpu number>,...,<cpu number>-<cpu number>
834 This option can be used to specify one or more CPUs
835 to isolate from the general SMP balancing and scheduling
836 algorithms. The only way to move a process onto or off
837 an "isolated" CPU is via the CPU affinity syscalls.
838 <cpu number> begins at 0 and the maximum value is
839 "number of CPUs in system - 1".
841 This option is the preferred way to isolate CPUs. The
842 alternative -- manually setting the CPU mask of all
843 tasks in the system -- can cause problems and
844 suboptimal load balancer performance.
848 js= [HW,JOY] Analog joystick
849 See Documentation/input/joystick.txt.
851 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
852 specifies the amount of memory usable by the kernel
853 for non-movable allocations. The requested amount is
854 spread evenly throughout all nodes in the system. The
855 remaining memory in each node is used for Movable
856 pages. In the event, a node is too small to have both
857 kernelcore and Movable pages, kernelcore pages will
858 take priority and other nodes will have a larger number
859 of kernelcore pages. The Movable zone is used for the
860 allocation of pages that may be reclaimed or moved
861 by the page migration subsystem. This means that
862 HugeTLB pages may not be allocated from this zone.
863 Note that allocations like PTEs-from-HighMem still
864 use the HighMem zone if it exists, and the Normal
867 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
868 is similar to kernelcore except it specifies the
869 amount of memory used for migratable allocations.
870 If both kernelcore and movablecore is specified,
871 then kernelcore will be at *least* the specified
872 value but may be more. If movablecore on its own
873 is specified, the administrator must be careful
874 that the amount of memory usable for all allocations
879 kstack=N [X86-32,X86-64] Print N words from the kernel stack
884 lapic [X86-32,APIC] Enable the local APIC even if BIOS
887 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
890 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
891 Format: addr:<io>,irq:<irq>
893 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
897 load_ramdisk= [RAM] List of ramdisks to load from floppy
898 See Documentation/ramdisk.txt.
900 lockd.nlm_grace_period=P [NFS] Assign grace period.
903 lockd.nlm_tcpport=N [NFS] Assign TCP port.
906 lockd.nlm_timeout=T [NFS] Assign timeout value.
909 lockd.nlm_udpport=M [NFS] Assign UDP port.
912 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
915 loglevel= All Kernel Messages with a loglevel smaller than the
916 console loglevel will be printed to the console. It can
917 also be changed with klogd or other programs. The
918 loglevels are defined as follows:
920 0 (KERN_EMERG) system is unusable
921 1 (KERN_ALERT) action must be taken immediately
922 2 (KERN_CRIT) critical conditions
923 3 (KERN_ERR) error conditions
924 4 (KERN_WARNING) warning conditions
925 5 (KERN_NOTICE) normal but significant condition
926 6 (KERN_INFO) informational
927 7 (KERN_DEBUG) debug-level messages
929 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
930 Format: { n | nk | nM }
931 n must be a power of two. The default size
932 is set in the kernel config file.
934 logo.nologo [FB] Disables display of the built-in Linux logo.
935 This may be used to provide more screen space for
936 kernel log messages and is useful when debugging
937 kernel boot problems.
939 lp=0 [LP] Specify parallel ports to use, e.g,
940 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
941 lp=reset first parallel port). 'lp=0' disables the
942 lp=auto printer driver. 'lp=reset' (which can be
943 specified in addition to the ports) causes
944 attached printers to be reset. Using
945 lp=port1,port2,... specifies the parallel ports
946 to associate lp devices with, starting with
947 lp0. A port specification may be 'none' to skip
948 that lp device, or a parport name such as
949 'parport0'. Specifying 'lp=auto' instead of a
950 port specification list means that device IDs
951 from each port should be examined, to see if
952 an IEEE 1284-compliant printer is attached; if
953 so, the driver will manage that printer.
954 See also header of drivers/char/lp.c.
957 Sets loops_per_jiffy to given constant, thus avoiding
958 time-consuming boot-time autodetection (up to 250 ms per
959 CPU). 0 enables autodetection (default). To determine
960 the correct value for your kernel, boot with normal
961 autodetection and see what value is printed. Note that
962 on SMP systems the preset will be applied to all CPUs,
963 which is likely to cause problems if your CPUs need
964 significantly divergent settings. An incorrect value
965 will cause delays in the kernel to be wrong, leading to
966 unpredictable I/O errors and other breakage. Although
967 unlikely, in the extreme case this might damage your
971 Format: <io>,<irq>,<dma>
973 mac5380= [HW,SCSI] Format:
974 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
976 mac53c9x= [HW,SCSI] Format:
977 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
979 machvec= [IA64] Force the use of a particular machine-vector
980 (machvec) in a generic kernel.
981 Example: machvec=hpzx1_swiotlb
983 max_loop= [LOOP] Maximum number of loopback devices that can
987 maxcpus= [SMP] Maximum number of processors that an SMP kernel
988 should make use of. maxcpus=n : n >= 0 limits the
989 kernel to using 'n' processors. n=0 is a special case,
990 it is equivalent to "nosmp", which also disables
993 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
994 equal to this physical address is ignored.
996 max_luns= [SCSI] Maximum number of LUNs to probe.
997 Should be between 1 and 2^32-1.
1000 [SCSI] Maximum number of LUNs received.
1001 Should be between 1 and 16384.
1003 mca-pentium [BUGS=X86-32]
1007 mce [X86-32] Machine Check Exception
1009 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1011 md= [HW] RAID subsystems devices and level
1012 See Documentation/md.txt.
1015 Format: <first>,<last>
1016 Specifies range of consoles to be captured by the MDA.
1018 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1019 Amount of memory to be used when the kernel is not able
1020 to see the whole system memory or for test.
1021 [X86-32] Use together with memmap= to avoid physical
1022 address space collisions. Without memmap= PCI devices
1023 could be placed at addresses belonging to unused RAM.
1025 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1028 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1029 E820 memory map, as specified by the user.
1030 Such memmap=exactmap lines can be constructed based on
1031 BIOS output or other requirements. See the memmap=nn@ss
1034 memmap=nn[KMG]@ss[KMG]
1035 [KNL] Force usage of a specific region of memory
1036 Region of memory to be used, from ss to ss+nn.
1038 memmap=nn[KMG]#ss[KMG]
1039 [KNL,ACPI] Mark specific memory as ACPI data.
1040 Region of memory to be used, from ss to ss+nn.
1042 memmap=nn[KMG]$ss[KMG]
1043 [KNL,ACPI] Mark specific memory as reserved.
1044 Region of memory to be used, from ss to ss+nn.
1046 meye.*= [HW] Set MotionEye Camera parameters
1047 See Documentation/video4linux/meye.txt.
1049 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1050 Multi-Function General Purpose Timers on AMD Geode
1056 [MOUSE] Maximum time between finger touching and
1057 leaving touchpad surface for touch to be considered
1058 a tap and be reported as a left button click (for
1059 touchpads working in absolute mode only).
1061 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1062 reporting absolute coordinates, such as tablets
1063 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1064 reporting absolute coordinates, such as tablets
1069 MTD_Partition= [MTD]
1070 Format: <name>,<region-number>,<size>,<offset>
1072 MTD_Region= [MTD] Format:
1073 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1076 See drivers/mtd/cmdlinepart.c.
1078 mtouchusb.raw_coordinates=
1079 [HW] Make the MicroTouch USB driver use raw coordinates
1080 ('y', default) or cooked coordinates ('n')
1082 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1085 See header of drivers/scsi/NCR_D700.c.
1089 ncr53c400= [HW,SCSI]
1091 ncr53c400a= [HW,SCSI]
1093 ncr53c406a= [HW,SCSI]
1095 ncr53c8xx= [HW,SCSI]
1097 netdev= [NET] Network devices parameters
1098 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1099 Note that mem_start is often overloaded to mean
1100 something different and driver-specific.
1101 This usage is only documented in each driver source
1105 See Documentation/nfsroot.txt.
1107 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1108 See Documentation/nfsroot.txt.
1110 nfs.callback_tcpport=
1111 [NFS] set the TCP port on which the NFSv4 callback
1112 channel should listen.
1114 nfs.idmap_cache_timeout=
1115 [NFS] set the maximum lifetime for idmapper cache
1119 [NFS] enable 64-bit inode numbers.
1120 If zero, the NFS client will fake up a 32-bit inode
1121 number for the readdir() and stat() syscalls instead
1122 of returning the full 64-bit number.
1123 The default is to return 64-bit inode numbers.
1125 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1127 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1128 emulation library even if a 387 maths coprocessor
1131 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1132 caches in the slab allocator. Saves per-node memory,
1133 but will impact performance.
1137 noapic [SMP,APIC] Tells the kernel to not make use of any
1138 IOAPICs that may be present in the system.
1140 noasync [HW,M68K] Disables async and sync negotiation for
1143 nobats [PPC] Do not use BATs for mapping kernel lowmem
1144 on "Classic" PPC cores.
1148 nodelayacct [KNL] Disable per-task delay accounting
1150 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1154 noexec [X86-32,X86-64]
1155 noexec=on: enable non-executable mappings (default)
1156 noexec=off: disable nn-executable mappings
1158 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1159 register save and restore. The kernel will only save
1160 legacy floating-point registers on task switch.
1164 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1165 instruction doesn't work correctly and not to
1168 nohalt [IA-64] Tells the kernel not to use the power saving
1169 function PAL_HALT_LIGHT when idle. This increases
1170 power-consumption. On the positive side, it reduces
1171 interrupt wake-up latency, which may improve performance
1172 in certain environments such as networked servers or
1175 nohz= [KNL] Boottime enable/disable dynamic ticks
1176 Valid arguments: on, off
1179 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1181 noirqdebug [X86-32] Disables the code which attempts to detect and
1182 disable unhandled interrupt sources.
1184 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1185 broken timer IRQ sources.
1187 noisapnp [ISAPNP] Disables ISA PnP code.
1189 noinitrd [RAM] Tells the kernel not to load any configured
1194 nojitter [IA64] Disables jitter checking for ITC timers.
1196 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1198 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1200 noltlbs [PPC] Do not use large page/tlb entries for kernel
1201 lowmem mapping on PPC40x.
1203 nomca [IA-64] Disable machine check abort handling
1205 nomce [X86-32] Machine Check Exception
1207 nomfgpt [X86-32] Disable Multi-Function General Purpose
1208 Timer usage (for AMD Geode machines).
1210 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1212 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1213 with UP alternatives
1215 noresidual [PPC] Don't use residual data on PReP machines.
1217 noresume [SWSUSP] Disables resume and restores original swap
1220 no-scroll [VGA] Disables scrollback.
1221 This is required for the Braillex ib80-piezo Braille
1222 reader made by F.H. Papenmeier (Germany).
1226 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1228 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1229 and disable the IO APIC. legacy for "maxcpus=0".
1231 nosoftlockup [KNL] Disable the soft-lockup detector.
1233 nosync [HW,M68K] Disables sync negotiation for all devices.
1235 notsc [BUGS=X86-32] Disable Time Stamp Counter
1237 nousb [USB] Disable the USB subsystem
1241 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1242 one of ['zone', 'node', 'default'] can be specified
1243 This can be set from sysctl after boot.
1244 See Documentation/sysctl/vm.txt for details.
1246 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1251 oprofile.timer= [HW]
1252 Use timer interrupt instead of performance counters
1254 osst= [HW,SCSI] SCSI Tape Driver
1255 Format: <buffer_size>,<write_threshold>
1256 See also Documentation/scsi/st.txt.
1258 panic= [KNL] Kernel behaviour on panic
1261 parkbd.port= [HW] Parallel port number the keyboard adapter is
1262 connected to, default is 0.
1264 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1265 0 for XT, 1 for AT (default is AT).
1268 parport= [HW,PPT] Specify parallel ports. 0 disables.
1269 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1270 Use 'auto' to force the driver to use any
1271 IRQ/DMA settings detected (the default is to
1272 ignore detected IRQ/DMA settings because of
1273 possible conflicts). You can specify the base
1274 address, IRQ, and DMA settings; IRQ and DMA
1275 should be numbers, or 'auto' (for using detected
1276 settings on that particular port), or 'nofifo'
1277 (to avoid using a FIFO even if it is detected).
1278 Parallel ports are assigned in the order they
1279 are specified on the command line, starting
1282 parport_init_mode= [HW,PPT]
1283 Configure VIA parallel port to operate in
1284 a specific mode. This is necessary on Pegasos
1285 computer where firmware has no options for setting
1286 up parallel port mode and sets it to spp.
1287 Currently this function knows 686a and 8231 chips.
1288 Format: [spp|ps2|epp|ecp|ecpepp]
1290 pas2= [HW,OSS] Format:
1291 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1294 See header of drivers/scsi/pas16.c.
1297 Halt all CPUs after the first oops has been printed for
1298 the specified number of seconds. This is to be used if
1299 your oopses keep scrolling off the screen.
1304 See header of drivers/block/paride/pcd.c.
1305 See also Documentation/paride.txt.
1307 pci=option[,option...] [PCI] various PCI subsystem options:
1308 off [X86-32] don't probe for the PCI bus
1309 bios [X86-32] force use of PCI BIOS, don't access
1310 the hardware directly. Use this if your machine
1311 has a non-standard PCI host bridge.
1312 nobios [X86-32] disallow use of PCI BIOS, only direct
1313 hardware access methods are allowed. Use this
1314 if you experience crashes upon bootup and you
1315 suspect they are caused by the BIOS.
1316 conf1 [X86-32] Force use of PCI Configuration
1318 conf2 [X86-32] Force use of PCI Configuration
1320 noaer [PCIE] If the PCIEAER kernel config parameter is
1321 enabled, this kernel boot option can be used to
1322 disable the use of PCIE advanced error reporting.
1323 nodomains [PCI] Disable support for multiple PCI
1324 root domains (aka PCI segments, in ACPI-speak).
1325 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1327 nomsi [MSI] If the PCI_MSI kernel config parameter is
1328 enabled, this kernel boot option can be used to
1329 disable the use of MSI interrupts system-wide.
1330 nosort [X86-32] Don't sort PCI devices according to
1331 order given by the PCI BIOS. This sorting is
1332 done to get a device order compatible with
1334 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1335 routing table. These calls are known to be buggy
1336 on several machines and they hang the machine
1337 when used, but on other computers it's the only
1338 way to get the interrupt routing table. Try
1339 this option if the kernel is unable to allocate
1340 IRQs or discover secondary PCI buses on your
1342 rom [X86-32] Assign address space to expansion ROMs.
1343 Use with caution as certain devices share
1344 address decoders between ROMs and other
1346 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1347 assigned automatically to PCI devices. You can
1348 make the kernel exclude IRQs of your ISA cards
1350 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1351 of the PIRQ table (normally generated
1352 by the BIOS) if it is outside the
1353 F0000h-100000h range.
1354 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1355 useful if the kernel is unable to find your
1356 secondary buses and you want to tell it
1357 explicitly which ones they are.
1358 assign-busses [X86-32] Always assign all PCI bus
1359 numbers ourselves, overriding
1360 whatever the firmware may have done.
1361 usepirqmask [X86-32] Honor the possible IRQ mask stored
1362 in the BIOS $PIR table. This is needed on
1363 some systems with broken BIOSes, notably
1364 some HP Pavilion N5400 and Omnibook XE3
1365 notebooks. This will have no effect if ACPI
1366 IRQ routing is enabled.
1367 noacpi [X86-32] Do not use ACPI for IRQ routing
1368 or for PCI scanning.
1369 use_crs [X86-32] Use _CRS for PCI resource
1371 routeirq Do IRQ routing for all PCI devices.
1372 This is normally done in pci_enable_device(),
1373 so this option is a temporary workaround
1374 for broken drivers that don't call it.
1375 firmware [ARM] Do not re-enumerate the bus but instead
1376 just use the configuration from the
1377 bootloader. This is currently used on
1378 IXP2000 systems where the bus has to be
1379 configured a certain way for adjunct CPUs.
1380 noearly [X86] Don't do any early type 1 scanning.
1381 This might help on some broken boards which
1382 machine check when some devices' config space
1383 is read. But various workarounds are disabled
1384 and some IOMMU drivers will not work.
1385 bfsort Sort PCI devices into breadth-first order.
1386 This sorting is done to get a device
1387 order compatible with older (<= 2.4) kernels.
1388 nobfsort Don't sort PCI devices into breadth-first order.
1389 cbiosize=nn[KMG] The fixed amount of bus space which is
1390 reserved for the CardBus bridge's IO window.
1391 The default value is 256 bytes.
1392 cbmemsize=nn[KMG] The fixed amount of bus space which is
1393 reserved for the CardBus bridge's memory
1394 window. The default value is 64 megabytes.
1396 pcmv= [HW,PCMCIA] BadgePAD 4
1399 See Documentation/paride.txt.
1401 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1404 See arch/parisc/kernel/pdc_chassis.c
1407 See Documentation/paride.txt.
1410 See Documentation/paride.txt.
1412 pirq= [SMP,APIC] Manual mp-table setup
1413 See Documentation/i386/IO-APIC.txt.
1415 plip= [PPT,NET] Parallel port network link
1416 Format: { parport<nr> | timid | 0 }
1417 See also Documentation/parport.txt.
1423 { on | off | curr | res | no-curr | no-res }
1426 [ISAPNP] Exclude IRQs for the autoconfiguration
1429 [ISAPNP] Exclude DMAs for the autoconfiguration
1431 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1432 Ranges are in pairs (I/O port base and size).
1435 [ISAPNP] Exclude memory regions for the
1437 Ranges are in pairs (memory base and size).
1439 print-fatal-signals=
1440 [KNL] debug: print fatal signals
1441 print-fatal-signals=1: print segfault info to
1445 printk.time= Show timing data prefixed to each printk message line
1446 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1448 profile= [KNL] Enable kernel profiling via /proc/profile
1449 Format: [schedule,]<number>
1450 Param: "schedule" - profile schedule points.
1451 Param: <number> - step/bucket size as a power of 2 for
1452 statistical time based profiling.
1453 Param: "sleep" - profile D-state sleeping (millisecs)
1455 processor.max_cstate= [HW,ACPI]
1456 Limit processor to maximum C-state
1457 max_cstate=9 overrides any DMI blacklist limit.
1459 processor.nocst [HW,ACPI]
1460 Ignore the _CST method to determine C-states,
1461 instead using the legacy FADT method
1463 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1465 See Documentation/ramdisk.txt.
1467 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1468 probe for; one of (bare|imps|exps|lifebook|any).
1469 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1471 psmouse.resetafter= [HW,MOUSE]
1472 Try to reset the device after so many bad packets
1475 [HW,MOUSE] Set desired mouse resolution, in dpi.
1476 psmouse.smartscroll=
1477 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1478 0 = disabled, 1 = enabled (default).
1480 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1482 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1485 See Documentation/paride.txt.
1488 [KNL] Number of legacy pty's. Overwrites compiled-in
1491 quiet [KNL] Disable most log messages
1496 See Documentation/md.txt.
1498 ramdisk_blocksize= [RAM]
1499 See Documentation/ramdisk.txt.
1501 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1502 See Documentation/ramdisk.txt.
1504 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1505 RCU callbacks to process in one batch.
1507 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1508 RCU callbacks over which batch limiting is disabled.
1510 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1511 RCU callbacks below which batch limiting is re-enabled.
1515 Run specified binary instead of /init from the ramdisk,
1516 used for early userspace startup. See initrd.
1518 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1519 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1520 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1522 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1524 reservetop= [X86-32]
1526 Reserves a hole at the top of the kernel virtual
1529 reset_devices [KNL] Force drivers to reset the underlying device
1530 during initialization.
1533 Specify the partition device for software suspend
1535 resume_offset= [SWSUSP]
1536 Specify the offset from the beginning of the partition
1537 given by "resume=" at which the swap header is located,
1538 in <PAGE_SIZE> units (needed only for swap files).
1539 See Documentation/power/swsusp-and-swap-files.txt
1541 retain_initrd [RAM] Keep initrd memory after extraction
1543 rhash_entries= [KNL,NET]
1544 Set number of hash buckets for route cache
1546 riscom8= [HW,SERIAL]
1547 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1549 ro [KNL] Mount root device read-only on boot
1551 root= [KNL] Root filesystem
1553 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1554 mount the root filesystem
1556 rootflags= [KNL] Set root filesystem mount option string
1558 rootfstype= [KNL] Set root filesystem type
1560 rootwait [KNL] Wait (indefinitely) for root device to show up.
1561 Useful for devices that are detected asynchronously
1562 (e.g. USB and MMC devices).
1564 root_plug.vendor_id=
1565 [ROOTPLUG] Override the default vendor ID
1567 root_plug.product_id=
1568 [ROOTPLUG] Override the default product ID
1571 [ROOTPLUG] Enable debugging output
1573 rw [KNL] Mount root device read-write on boot
1575 S [KNL] Run init in single mode
1578 See drivers/net/irda/sa1100_ir.c.
1581 Format: <io>,<irq>,<dma>,<dma2>
1583 sbni= [NET] Granch SBNI12 leased line adapter
1585 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1586 Format: <io>[,<timeout>[,<isapnp>]]
1588 scsi_debug_*= [SCSI]
1589 See drivers/scsi/scsi_debug.c.
1591 scsi_default_dev_flags=
1592 [SCSI] SCSI default device flags
1595 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1596 Format: <vendor>:<model>:<flags>
1597 (flags are integer value)
1599 scsi_logging= [SCSI]
1601 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1602 discovered. async scans them in kernel threads,
1603 allowing boot to proceed. none ignores them, expecting
1604 user space to do the scan.
1606 selinux [SELINUX] Disable or enable SELinux at boot time.
1607 Format: { "0" | "1" }
1608 See security/selinux/Kconfig help text.
1611 Default value is set via kernel config option.
1612 If enabled at boot time, /selinux/disable can be used
1613 later to disable prior to initial policy load.
1615 selinux_compat_net =
1616 [SELINUX] Set initial selinux_compat_net flag value.
1617 Format: { "0" | "1" }
1618 0 -- use new secmark-based packet controls
1619 1 -- use legacy packet controls
1620 Default value is 0 (preferred).
1621 Value can be changed at runtime via
1622 /selinux/compat_net.
1624 serialnumber [BUGS=X86-32]
1626 sg_def_reserved_size= [SCSI]
1629 Maximal number of shapers.
1632 See header of drivers/scsi/sim710.c.
1639 slub_debug[=options[,slabs]] [MM, SLUB]
1640 Enabling slub_debug allows one to determine the
1641 culprit if slab objects become corrupted. Enabling
1642 slub_debug can create guard zones around objects and
1643 may poison objects when not in use. Also tracks the
1644 last alloc / free. For more information see
1645 Documentation/vm/slub.txt.
1647 slub_max_order= [MM, SLUB]
1648 Determines the maximum allowed order for slabs.
1649 A high setting may cause OOMs due to memory
1650 fragmentation. For more information see
1651 Documentation/vm/slub.txt.
1653 slub_min_objects= [MM, SLUB]
1654 The minimum number of objects per slab. SLUB will
1655 increase the slab order up to slub_max_order to
1656 generate a sufficiently large slab able to contain
1657 the number of objects indicated. The higher the number
1658 of objects the smaller the overhead of tracking slabs
1659 and the less frequently locks need to be acquired.
1660 For more information see Documentation/vm/slub.txt.
1662 slub_min_order= [MM, SLUB]
1663 Determines the mininum page order for slabs. Must be
1664 lower than slub_max_order.
1665 For more information see Documentation/vm/slub.txt.
1667 slub_nomerge [MM, SLUB]
1668 Disable merging of slabs with similar size. May be
1669 necessary if there is some reason to distinguish
1670 allocs to different slabs. Debug options disable
1671 merging on their own.
1672 For more information see Documentation/vm/slub.txt.
1675 Format: <io1>[,<io2>[,...,<io8>]]
1677 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1678 attempt to substitute SMP alternatives once at boot.
1680 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1681 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1682 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1683 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1684 smsc-ircc2.ircc_irq= [HW] IRQ line
1685 smsc-ircc2.ircc_dma= [HW] DMA channel
1686 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1687 0: Toshiba Satellite 1800 (GP data pin select)
1688 1: Fast pin select (default)
1691 snd-ad1816a= [HW,ALSA]
1693 snd-ad1848= [HW,ALSA]
1695 snd-ali5451= [HW,ALSA]
1697 snd-als100= [HW,ALSA]
1699 snd-als4000= [HW,ALSA]
1701 snd-azt2320= [HW,ALSA]
1703 snd-cmi8330= [HW,ALSA]
1705 snd-cmipci= [HW,ALSA]
1707 snd-cs4231= [HW,ALSA]
1709 snd-cs4232= [HW,ALSA]
1711 snd-cs4236= [HW,ALSA]
1713 snd-cs4281= [HW,ALSA]
1715 snd-cs46xx= [HW,ALSA]
1717 snd-dt019x= [HW,ALSA]
1719 snd-dummy= [HW,ALSA]
1721 snd-emu10k1= [HW,ALSA]
1723 snd-ens1370= [HW,ALSA]
1725 snd-ens1371= [HW,ALSA]
1727 snd-es968= [HW,ALSA]
1729 snd-es1688= [HW,ALSA]
1731 snd-es18xx= [HW,ALSA]
1733 snd-es1938= [HW,ALSA]
1735 snd-es1968= [HW,ALSA]
1737 snd-fm801= [HW,ALSA]
1739 snd-gusclassic= [HW,ALSA]
1741 snd-gusextreme= [HW,ALSA]
1743 snd-gusmax= [HW,ALSA]
1747 snd-ice1712= [HW,ALSA]
1749 snd-intel8x0= [HW,ALSA]
1751 snd-interwave= [HW,ALSA]
1756 snd-korg1212= [HW,ALSA]
1758 snd-maestro3= [HW,ALSA]
1760 snd-mpu401= [HW,ALSA]
1762 snd-mtpav= [HW,ALSA]
1764 snd-nm256= [HW,ALSA]
1766 snd-opl3sa2= [HW,ALSA]
1774 snd-opti93x= [HW,ALSA]
1778 snd-rme32= [HW,ALSA]
1780 snd-rme96= [HW,ALSA]
1782 snd-rme9652= [HW,ALSA]
1788 snd-sbawe= [HW,ALSA]
1790 snd-serial= [HW,ALSA]
1792 snd-sgalaxy= [HW,ALSA]
1794 snd-sonicvibes= [HW,ALSA]
1799 snd-sun-cs4231= [HW,ALSA]
1801 snd-trident= [HW,ALSA]
1803 snd-usb-audio= [HW,ALSA,USB]
1805 snd-via82xx= [HW,ALSA]
1807 snd-virmidi= [HW,ALSA]
1809 snd-wavefront= [HW,ALSA]
1811 snd-ymfpci= [HW,ALSA]
1813 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1814 See Documentation/sonypi.txt
1816 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1817 See Documentation/specialix.txt.
1819 spia_io_base= [HW,MTD]
1825 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1827 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1828 See Documentation/scsi/st.txt.
1831 See header of drivers/scsi/seagate.c.
1835 Set the STI (builtin display/keyboard on the HP-PARISC
1836 machines) console (graphic card) which should be used
1837 as the initial boot-console.
1838 See also comment in drivers/video/console/sticore.c.
1841 See comment in drivers/video/console/sticore.c.
1844 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1848 Control how the NFS server code allocates CPUs to
1849 service thread pools. Depending on how many NICs
1850 you have and where their interrupts are bound, this
1851 option will affect which CPUs will do NFS serving.
1852 Note: this parameter cannot be changed while the
1853 NFS server is running.
1855 auto the server chooses an appropriate mode
1856 automatically using heuristics
1857 global a single global pool contains all CPUs
1858 percpu one pool for each CPU
1859 pernode one pool for each NUMA node (equivalent
1860 to global on non-NUMA machines)
1862 swiotlb= [IA-64] Number of I/O TLB slabs
1866 sym53c416= [HW,SCSI]
1867 See header of drivers/scsi/sym53c416.c.
1869 sysrq_always_enabled
1871 Ignore sysrq setting - this boot parameter will
1872 neutralize any effect of /proc/sys/kernel/sysrq.
1873 Useful for debugging.
1876 See header of drivers/scsi/t128.c.
1880 thash_entries= [KNL,NET]
1881 Set number of hash buckets for TCP connection
1883 thermal.act= [HW,ACPI]
1884 -1: disable all active trip points in all thermal zones
1885 <degrees C>: override all lowest active trip points
1887 thermal.crt= [HW,ACPI]
1888 -1: disable all critical trip points in all thermal zones
1889 <degrees C>: lower all critical trip points
1891 thermal.nocrt= [HW,ACPI]
1892 Set to disable actions on ACPI thermal zone
1893 critical and hot trip points.
1895 thermal.off= [HW,ACPI]
1896 1: disable ACPI thermal control
1898 thermal.psv= [HW,ACPI]
1899 -1: disable all passive trip points
1900 <degrees C>: override all passive trip points to this value
1902 thermal.tzp= [HW,ACPI]
1903 Specify global default ACPI thermal zone polling rate
1904 <deci-seconds>: poll all this frequency
1905 0: no polling (default)
1907 time Show timing data prefixed to each printk message line
1908 [deprecated, see 'printk.time']
1910 tipar.timeout= [HW,PPT]
1911 Set communications timeout in tenths of a second
1914 tipar.delay= [HW,PPT]
1915 Set inter-bit delay in microseconds (default 10).
1918 See header of drivers/scsi/seagate.c.
1921 See comment before function dc390_setup() in
1922 drivers/scsi/tmscsim.c.
1926 trix= [HW,OSS] MediaTrix AudioTrix Pro
1928 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1930 turbografx.map[2|3]= [HW,JOY]
1931 TurboGraFX parallel port interface
1933 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1934 See also Documentation/input/joystick-parport.txt
1936 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1937 See header of drivers/scsi/u14-34f.c.
1946 [USB] Ignore overcurrent events (default N).
1947 Some badly-designed motherboards generate lots of
1948 bogus events, for ports that aren't wired to
1949 anything. Set this parameter to avoid log spamming.
1950 Note that genuine overcurrent events won't be
1953 usbcore.autosuspend=
1954 [USB] The autosuspend time delay (in seconds) used
1955 for newly-detected USB devices (default 2). This
1956 is the time required before an idle device will be
1957 autosuspended. Devices for which the delay is set
1958 to a negative value won't be autosuspended at all.
1961 [USBHID] The interval which mice are to be polled at.
1963 vdso= [X86-32,SH,x86-64]
1964 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1965 vdso=1: enable VDSO (default)
1966 vdso=0: disable VDSO mapping
1969 vector=percpu: enable percpu vector domain
1971 video= [FB] Frame buffer configuration
1972 See Documentation/fb/modedb.txt.
1974 vga= [BOOT,X86-32] Select a particular video mode
1975 See Documentation/i386/boot.txt and
1976 Documentation/svga.txt.
1977 Use vga=ask for menu.
1978 This is actually a boot loader parameter; the value is
1979 passed to the kernel using a special protocol.
1981 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1982 size of <nn>. This can be used to increase the
1983 minimum size (128MB on x86). It can also be used to
1984 decrease the size and leave more room for directly
1987 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1990 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1993 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1996 waveartist= [HW,OSS]
1997 Format: <io>,<irq>,<dma>,<dma2>
2000 See header of drivers/scsi/wd33c93.c.
2003 See header of drivers/scsi/wd7000.c.
2006 See Documentation/watchdog/wdt.txt.
2008 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2009 xd_geo= See header of drivers/block/xd.c.
2011 xirc2ps_cs= [NET,PCMCIA]
2013 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2015 norandmaps Don't use address space randomization
2016 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2018 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
2019 This is useful to get more information why
2020 you got a "dwarf2 unwinder stuck"
2022 ______________________________________________________________________
2026 Add documentation for ALSA options.
2027 Add more DRM drivers.