4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
38 DRM Direct Rendering Management support is enabled.
39 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LIBATA Libata driver is enabled
52 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
60 MSI Message Signaled Interrupts (PCI).
61 MTD MTD support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
64 GENERIC_TIME The generic timeofday code is enabled.
65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PV_OPS A paravirtualized kernel
68 PARIDE The ParIDE subsystem is enabled.
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCMCIA The PCMCIA subsystem is enabled.
72 PNP Plug & Play support is enabled.
73 PPC PowerPC architecture is enabled.
74 PPT Parallel port support is enabled.
75 PS2 Appropriate PS/2 support is enabled.
76 RAM RAM disk support is enabled.
77 S390 S390 architecture is enabled.
78 SCSI Appropriate SCSI support is enabled.
79 A lot of drivers has their options described inside of
81 SELINUX SELinux support is enabled.
82 SERIAL Serial support is enabled.
83 SH SuperH architecture is enabled.
84 SMP The kernel is an SMP kernel.
85 SPARC Sparc architecture is enabled.
86 SWSUSP Software suspend is enabled.
87 TS Appropriate touchscreen support is enabled.
88 USB USB support is enabled.
89 USBHID USB Human Interface Device support is enabled.
90 V4L Video For Linux support is enabled.
91 VGA The VGA console has been enabled.
92 VT Virtual terminal support is enabled.
93 WDT Watchdog support is enabled.
94 XT IBM PC/XT MFM hard disk support is enabled.
95 X86-64 X86-64 architecture is enabled.
96 More X86-64 boot options can be found in
97 Documentation/x86_64/boot-options.txt .
99 In addition, the following text indicates that the option:
101 BUGS= Relates to possible processor bugs on the said processor.
102 KNL Is a kernel start-up parameter.
103 BOOT Is a boot loader parameter.
105 Parameters denoted with BOOT are actually interpreted by the boot
106 loader, and have no meaning to the kernel directly.
107 Do not modify the syntax of boot loader parameters without extreme
108 need or coordination with <Documentation/i386/boot.txt>.
110 There are also arch-specific kernel-parameters not documented here.
111 See for example <Documentation/x86_64/boot-options.txt>.
113 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
114 a trailing = on the name of any parameter states that that parameter will
115 be entered as an environment variable, whereas its absence indicates that
116 it will appear as a kernel argument readable via /proc/cmdline by programs
117 running once the system is up.
119 The number of kernel parameters is not limited, but the length of the
120 complete command line (parameters including spaces etc.) is limited to
121 a fixed number of characters. This limit depends on the architecture
122 and is between 256 and 4096 characters. It is defined in the file
123 ./include/asm/setup.h as COMMAND_LINE_SIZE.
126 53c7xx= [HW,SCSI] Amiga SCSI controllers
127 See header of drivers/scsi/53c7xx.c.
128 See also Documentation/scsi/ncr53c7xx.txt.
130 acpi= [HW,ACPI,X86-64,i386]
131 Advanced Configuration and Power Interface
132 Format: { force | off | ht | strict | noirq }
133 force -- enable ACPI if default was off
134 off -- disable ACPI if default was on
135 noirq -- do not use ACPI for IRQ routing
136 ht -- run only enough ACPI to enable Hyper Threading
137 strict -- Be less tolerant of platforms that are not
138 strictly ACPI specification compliant.
140 See also Documentation/pm.txt, pci=noacpi
142 acpi_apic_instance= [ACPI, IOAPIC]
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
148 acpi_sleep= [HW,ACPI] Sleep options
149 Format: { s3_bios, s3_mode }
150 See Documentation/power/video.txt
152 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
153 Format: { level | edge | high | low }
155 acpi_irq_balance [HW,ACPI]
156 ACPI will balance active IRQs
159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
165 Format: <irq>,<irq>...
167 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
168 Format: <irq>,<irq>...
170 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
171 Format: To spoof as Windows 98: ="Microsoft Windows"
173 acpi_osi= [HW,ACPI] empty param disables _OSI
175 acpi_serialize [HW,ACPI] force serialization of AML methods
177 acpi_skip_timer_override [HW,ACPI]
178 Recognize and ignore IRQ0/pin2 Interrupt Override.
179 For broken nForce2 BIOS resulting in XT-PIC timer.
180 acpi_use_timer_override [HW,ACPI}
181 Use timer override. For some broken Nvidia NF5 boards
182 that require a timer override, but don't have
185 acpi.debug_layer= [HW,ACPI]
187 Each bit of the <int> indicates an ACPI debug layer,
188 1: enable, 0: disable. It is useful for boot time
189 debugging. After system has booted up, it can be set
190 via /sys/module/acpi/parameters/debug_layer.
191 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
192 Available bits (add the numbers together) to enable debug output
193 for specific parts of the ACPI subsystem:
194 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
195 0x10 namespace 0x20 parser 0x40 dispatcher
196 0x80 executer 0x100 resources 0x200 acpica debugger
197 0x400 os services 0x800 acpica disassembler.
198 The number can be in decimal or prefixed with 0x in hex.
199 Warning: Many of these options can produce a lot of
200 output and make your system unusable. Be very careful.
202 acpi.debug_level= [HW,ACPI]
204 Each bit of the <int> indicates an ACPI debug level,
205 1: enable, 0: disable. It is useful for boot time
206 debugging. After system has booted up, it can be set
207 via /sys/module/acpi/parameters/debug_level.
208 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
209 Available bits (add the numbers together) to enable different
210 debug output levels of the ACPI subsystem:
211 0x01 error 0x02 warn 0x04 init 0x08 debug object
212 0x10 info 0x20 init names 0x40 parse 0x80 load
213 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
214 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
215 0x10000 resources 0x20000 user requests 0x40000 package.
216 The number can be in decimal or prefixed with 0x in hex.
217 Warning: Many of these options can produce a lot of
218 output and make your system unusable. Be very careful.
221 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
223 acpi_generic_hotkey [HW,ACPI]
224 Allow consolidated generic hotkey driver to
225 override platform specific driver.
226 See also Documentation/acpi-hotkey.txt.
228 acpi_pm_good [IA-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.
233 enable_timer_pin_1 [i386,x86-64]
234 Enable PIN 1 of APIC timer
235 Can be useful to work around chipset bugs
236 (in particular on some ATI chipsets).
237 The kernel tries to set a reasonable default.
239 disable_timer_pin_1 [i386,x86-64]
240 Disable PIN 1 of APIC timer
241 Can be useful to work around chipset bugs.
244 Format: <io>,<irq>,<dma>,<dma2>
245 See also Documentation/sound/oss/AD1816.
248 Format: <io>,<irq>,<dma>,<dma2>,<type>
254 See header of drivers/scsi/advansys.c.
256 advwdt= [HW,WDT] Advantech WDT
257 Format: <iostart>,<iostop>
259 aedsp16= [HW,OSS] Audio Excel DSP 16
260 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
261 See also header of sound/oss/aedsp16.c.
264 See Documentation/scsi/aha152x.txt.
267 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
270 See Documentation/scsi/aic7xxx.txt.
273 See Documentation/scsi/aic79xx.txt.
275 amijoy.map= [HW,JOY] Amiga joystick support
276 Map of devices attached to JOY0DAT and JOY1DAT
278 See also Documentation/kernel/input/joystick.txt
280 analog.map= [HW,JOY] Analog joystick and gamepad support
281 Specifies type or capabilities of an analog joystick
282 connected to one of 16 gameports
283 Format: <type1>,<type2>,..<type16>
286 Power management functions (SPARCstation-4/5 + deriv.)
288 Disable APC CPU standby support. SPARCstation-Fox does
289 not play well with APC CPU idle - disable it if you have
290 APC and your system crashes randomly.
292 apic= [APIC,i386] 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 aztcd= [HW,CD] Aztech CD268 CDROM driver
332 Format: <io>,0x79 (?)
334 baycom_epp= [HW,AX25]
337 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
339 See header of drivers/net/hamradio/baycom_par.c.
341 baycom_ser_fdx= [HW,AX25]
342 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
343 Format: <io>,<irq>,<mode>[,<baud>]
344 See header of drivers/net/hamradio/baycom_ser_fdx.c.
346 baycom_ser_hdx= [HW,AX25]
347 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
348 Format: <io>,<irq>,<mode>
349 See header of drivers/net/hamradio/baycom_ser_hdx.c.
351 blkmtd_device= [HW,MTD]
357 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
358 bttv.radio= Most important insmod options are available as
360 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
361 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
364 See drivers/scsi/BusLogic.c, comment before function
365 BusLogic_ParseDriverOptions().
367 c101= [NET] Moxa C101 synchronous serial card
369 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
370 Sometimes CPU hardware bugs make them report the cache
371 size incorrectly. The kernel will attempt work arounds
372 to fix known problems, but for some CPUs it is not
373 possible to determine what the correct size should be.
374 This option provides an override for these situations.
377 Format: <io>,<irq>[,PAS]
378 See header of drivers/cdrom/cdu31a.c.
380 chandev= [HW,NET] Generic channel device initialisation
382 checkreqprot [SELINUX] Set initial checkreqprot flag value.
383 Format: { "0" | "1" }
384 See security/selinux/Kconfig help text.
385 0 -- check protection applied by kernel (includes
386 any implied execute protection).
387 1 -- check protection requested by application.
388 Default value is set via a kernel config option.
389 Value can be changed at runtime via
390 /selinux/checkreqprot.
392 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
394 Forces specified clocksource (if available) to be used
395 when calculating gettimeofday(). If specified
396 clocksource is not available, it defaults to PIT.
397 Format: { pit | tsc | cyclone | pmtmr }
399 code_bytes [IA32] How many bytes of object code to print in an
406 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
407 over the 8254 in addition to over the IO-APIC. The
408 kernel tries to set a sensible default.
410 hpet= [IA-32,HPET] option to disable HPET and use PIT.
414 Format: { auto | [<io>,][<irq>] }
416 com20020= [HW,NET] ARCnet - COM20020 chipset
418 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
420 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
424 ARCnet - COM90xx chipset (memory-mapped buffers)
425 Format: <io>[,<irq>[,<memstart>]]
427 condev= [HW,S390] console device
430 console= [KNL] Output console device and options.
432 tty<n> Use the virtual console device <n>.
436 Use the specified serial port. The options are of
437 the form "bbbbpnf", where "bbbb" is the baud rate,
438 "p" is parity ("n", "o", or "e"), "n" is number of
439 bits, and "f" is flow control ("r" for RTS or
440 omit it). Default is "9600n8".
442 See Documentation/serial-console.txt for more
444 Documentation/networking/netconsole.txt for an
447 uart,io,<addr>[,options]
448 uart,mmio,<addr>[,options]
449 Start an early, polled-mode console on the 8250/16550
450 UART at the specified I/O port or MMIO address,
451 switching to the matching ttyS device later. The
452 options are the same as for ttyS, above.
454 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
456 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
459 Format: { parport<nr> | auto | none }
461 crashkernel=nn[KMG]@ss[KMG]
462 [KNL] Reserve a chunk of physical memory to
463 hold a kernel to switch to with kexec on panic.
466 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
471 cs89x0_media= [HW,NET]
472 Format: { rj45 | aui | bnc }
474 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
477 See header of drivers/s390/block/dasd_devmap.c.
479 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
480 (one device per port)
481 Format: <port#>,<type>
482 See also Documentation/input/joystick-parport.txt
484 debug [KNL] Enable kernel debugging (events log level).
487 [KNL] verbose self-tests
489 Print debugging info while doing the locking API
491 We default to 0 (no extra messages), setting it to
492 1 will print _a lot_ more information - normally
493 only useful to kernel developers.
496 Format: <area>[,<node>]
497 See also Documentation/networking/decnet.txt.
500 Set number of hash buckets for dentry cache.
503 IO parameters + enable/disable command.
505 digiepca= [HW,SERIAL]
506 See drivers/char/README.epca and
507 Documentation/digiepca.txt.
509 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
511 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
513 dmasound= [HW,OSS] Sound subsystem buffers
519 earlyprintk= [IA-32,X86-64,SH]
521 earlyprintk=serial[,ttySn[,baudrate]]
523 Append ",keep" to not disable it when the real console
526 Only vga or serial at a time, not both.
528 Currently only ttyS0 and ttyS1 are supported.
530 Interaction with the standard serial driver is not
533 The VGA output is eventually overwritten by the real
538 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
541 non-0: interrupt mode (default)
548 Format: {"of[f]" | "sk[ipmbr]"}
549 See comment in arch/i386/boot/edd.S
552 Format: <id>,<membase>,<irq>
554 eisa_irq_edge= [PARISC,HW]
555 See header of drivers/parisc/eisa.c.
558 See comment before function elanfreq_setup() in
559 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
562 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
563 See Documentation/block/as-iosched.txt and
564 Documentation/block/deadline-iosched.txt for details.
566 elfcorehdr= [IA-32, X86_64]
567 Specifies physical address of start of kernel core
568 image elf header. Generally kexec loader will
569 pass this option to capture kernel.
570 See Documentation/kdump/kdump.txt for details.
572 enforcing [SELINUX] Set initial enforcing status.
574 See security/selinux/Kconfig help text.
575 0 -- permissive (log only, no denials).
576 1 -- enforcing (deny and log).
578 Value can be changed at runtime via /selinux/enforce.
581 Format: <spdif>,[<nomix>,[<amplifier>]]
582 See also header of sound/oss/es1371.c.
584 ether= [HW,NET] Ethernet cards parameters
585 This option is obsoleted by the "netdev=" option, which
586 has equivalent usage. See its documentation for details.
588 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
593 fail_make_request=[KNL]
594 General fault injection mechanism.
595 Format: <interval>,<probability>,<space>,<times>
596 See also /Documentation/fault-injection/.
599 See header of drivers/scsi/fd_mcs.c.
602 See header of drivers/scsi/fdomain.c.
605 See Documentation/floppy.txt.
608 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
609 support via parallel port (up to 5 devices per port)
610 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
611 See also Documentation/input/joystick-parport.txt
616 See header of drivers/scsi/gdth.c.
618 gpt [EFI] Forces disk with valid GPT signature but
619 invalid Protective MBR to be treated as GPT.
626 hashdist= [KNL,NUMA] Large hashes allocated during boot
627 are distributed across NUMA nodes. Defaults on
628 for IA-64, off otherwise.
629 Format: 0 | 1 (for off | on)
631 hcl= [IA-64] SGI's Hardware Graph compatibility layer
633 hd= [EIDE] (E)IDE hard drive subsystem geometry
634 Format: <cyl>,<head>,<sect>
636 hd?= [HW] (E)IDE subsystem
637 hd?lun= See Documentation/ide.txt.
639 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
640 size of <nn>. This works even on boxes that have no
641 highmem otherwise. This also works to reduce highmem
642 size on bigger boxes.
644 highres= [KNL] Enable/disable high resolution timer mode.
645 Valid parameters: "on", "off"
649 See Documentation/isdn/README.HiSax.
651 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
653 i8042.direct [HW] Put keyboard port into non-translated mode
654 i8042.dumbkbd [HW] Pretend that controller can only read data from
655 keyboard and cannot control its state
656 (Don't attempt to blink the leds)
657 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
658 i8042.nokbd [HW] Don't check/create keyboard port
659 i8042.nomux [HW] Don't check presence of an active multiplexing
661 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
664 [HW] Frequency with which keyboard LEDs should blink
665 when kernel panics (default is 0.5 sec)
666 i8042.reset [HW] Reset the controller during init and cleanup
667 i8042.unlock [HW] Unlock (ignore) the keylock
671 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
672 indicates that the driver is running on unsupported
674 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
675 does not match list of supported models.
677 [HW] Report power status in /proc/i8k
678 (disabled by default)
679 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
682 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
683 See Documentation/mca.txt.
686 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
688 ide= [HW] (E)IDE subsystem
689 Format: ide=nodma or ide=doubler or ide=reverse
690 See Documentation/ide.txt.
692 ide?= [HW] (E)IDE subsystem
693 Format: ide?=noprobe or chipset specific parameters.
694 See Documentation/ide.txt.
696 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
697 See Documentation/ide.txt.
700 Format: idle=poll or idle=mwait
701 Poll forces a polling idle loop that can slightly improves the performance
702 of waking up a idle CPU, but will use a lot of power and make the system
703 run hot. Not recommended.
704 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
705 to not use it because it doesn't save as much power as a normal idle
706 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
709 ignore_loglevel [KNL]
710 Ignore loglevel setting - this will print /all/
711 kernel messages to the console. Useful for debugging.
714 Set number of hash buckets for inode cache.
717 See header of drivers/scsi/in2000.c.
721 Run specified binary instead of /sbin/init as init
724 initcall_debug [KNL] Trace initcalls as they are executed. Useful
725 for working out where the kernel is dying during
728 initrd= [BOOT] Specify the location of the initial ramdisk
730 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
733 combined_mode= [HW] control which driver uses IDE ports in combined
734 mode: legacy IDE driver, libata, or both
735 (in the libata case, libata.atapi_enabled=1 may be
736 useful as well). Note that using the ide or libata
737 options may affect your device naming (e.g. by
738 changing hdc to sdb).
739 Format: combined (default), ide, or libata
743 io7= [HW] IO7 for Marvel based alpha systems
744 See comment before marvel_specify_io7 in
745 arch/alpha/kernel/core_marvel.c.
748 See Documentation/nfsroot.txt.
750 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
751 See comment before ip2_setup() in drivers/char/ip2.c.
753 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
754 See header of drivers/scsi/ips.c.
756 ports= [IP_VS_FTP] IPVS ftp helper module
758 Up to 8 (IP_VS_APP_MAX_PORTS) ports
760 Format: <port>,<port>....
763 When an interrupt is not handled search all handlers
764 for it. Intended to get systems with badly broken
768 When an interrupt is not handled search all handlers
769 for it. Also check all handlers each timer
770 interrupt. Intended to get systems with badly broken
774 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
776 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
778 <cpu number>,...,<cpu number>
780 <cpu number>-<cpu number> (must be a positive range in ascending order)
782 <cpu number>,...,<cpu number>-<cpu number>
783 This option can be used to specify one or more CPUs
784 to isolate from the general SMP balancing and scheduling
785 algorithms. The only way to move a process onto or off
786 an "isolated" CPU is via the CPU affinity syscalls.
787 <cpu number> begins at 0 and the maximum value is
788 "number of CPUs in system - 1".
790 This option is the preferred way to isolate CPUs. The
791 alternative -- manually setting the CPU mask of all
792 tasks in the system -- can cause problems and
793 suboptimal load balancer performance.
796 Format: <io>,<irq>,<dma>,<setup>
800 js= [HW,JOY] Analog joystick
801 See Documentation/input/joystick.txt.
805 kstack=N [IA-32,X86-64] Print N words from the kernel stack
810 lapic [IA-32,APIC] Enable the local APIC even if BIOS
813 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
816 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
817 Format: addr:<io>,irq:<irq>
819 legacy_serial.force [HW,IA-32,X86-64]
820 Probe for COM ports at legacy addresses even
821 if PNPBIOS or ACPI should describe them. This
822 is for working around firmware defects.
824 llsc*= [IA64] See function print_params() in
825 arch/ia64/sn/kernel/llsc4.c.
827 load_ramdisk= [RAM] List of ramdisks to load from floppy
828 See Documentation/ramdisk.txt.
830 lockd.nlm_grace_period=P [NFS] Assign grace period.
833 lockd.nlm_tcpport=N [NFS] Assign TCP port.
836 lockd.nlm_timeout=T [NFS] Assign timeout value.
839 lockd.nlm_udpport=M [NFS] Assign UDP port.
842 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
845 loglevel= All Kernel Messages with a loglevel smaller than the
846 console loglevel will be printed to the console. It can
847 also be changed with klogd or other programs. The
848 loglevels are defined as follows:
850 0 (KERN_EMERG) system is unusable
851 1 (KERN_ALERT) action must be taken immediately
852 2 (KERN_CRIT) critical conditions
853 3 (KERN_ERR) error conditions
854 4 (KERN_WARNING) warning conditions
855 5 (KERN_NOTICE) normal but significant condition
856 6 (KERN_INFO) informational
857 7 (KERN_DEBUG) debug-level messages
859 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
860 Format: { n | nk | nM }
861 n must be a power of two. The default size
862 is set in the kernel config file.
864 lp=0 [LP] Specify parallel ports to use, e.g,
865 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
866 lp=reset first parallel port). 'lp=0' disables the
867 lp=auto printer driver. 'lp=reset' (which can be
868 specified in addition to the ports) causes
869 attached printers to be reset. Using
870 lp=port1,port2,... specifies the parallel ports
871 to associate lp devices with, starting with
872 lp0. A port specification may be 'none' to skip
873 that lp device, or a parport name such as
874 'parport0'. Specifying 'lp=auto' instead of a
875 port specification list means that device IDs
876 from each port should be examined, to see if
877 an IEEE 1284-compliant printer is attached; if
878 so, the driver will manage that printer.
879 See also header of drivers/char/lp.c.
882 Sets loops_per_jiffy to given constant, thus avoiding
883 time-consuming boot-time autodetection (up to 250 ms per
884 CPU). 0 enables autodetection (default). To determine
885 the correct value for your kernel, boot with normal
886 autodetection and see what value is printed. Note that
887 on SMP systems the preset will be applied to all CPUs,
888 which is likely to cause problems if your CPUs need
889 significantly divergent settings. An incorrect value
890 will cause delays in the kernel to be wrong, leading to
891 unpredictable I/O errors and other breakage. Although
892 unlikely, in the extreme case this might damage your
896 Format: <io>,<irq>,<dma>
898 mac5380= [HW,SCSI] Format:
899 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
901 mac53c9x= [HW,SCSI] Format:
902 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
904 machvec= [IA64] Force the use of a particular machine-vector
905 (machvec) in a generic kernel.
906 Example: machvec=hpzx1_swiotlb
908 max_loop= [LOOP] Maximum number of loopback devices that can
912 maxcpus= [SMP] Maximum number of processors that an SMP kernel
914 Using "nosmp" or "maxcpus=0" will disable SMP
915 entirely (the MPS table probe still happens, though).
916 A command-line option of "maxcpus=<NUM>", where <NUM>
917 is an integer greater than 0, limits the maximum number
918 of CPUs activated in SMP mode to <NUM>.
919 Using "maxcpus=1" on an SMP kernel is the trivial
920 case of an SMP kernel with only one CPU.
922 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
923 equal to this physical address is ignored.
925 max_luns= [SCSI] Maximum number of LUNs to probe.
926 Should be between 1 and 2^32-1.
929 [SCSI] Maximum number of LUNs received.
930 Should be between 1 and 16384.
932 mca-pentium [BUGS=IA-32]
937 Format: <port>,<irq>,<mitsumi_bug_93_wait>
941 mce [IA-32] Machine Check Exception
943 md= [HW] RAID subsystems devices and level
944 See Documentation/md.txt.
947 Format: <first>,<last>
948 Specifies range of consoles to be captured by the MDA.
950 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
951 Amount of memory to be used when the kernel is not able
952 to see the whole system memory or for test.
953 [IA-32] Use together with memmap= to avoid physical
954 address space collisions. Without memmap= PCI devices
955 could be placed at addresses belonging to unused RAM.
957 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
960 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
961 E820 memory map, as specified by the user.
962 Such memmap=exactmap lines can be constructed based on
963 BIOS output or other requirements. See the memmap=nn@ss
966 memmap=nn[KMG]@ss[KMG]
967 [KNL] Force usage of a specific region of memory
968 Region of memory to be used, from ss to ss+nn.
970 memmap=nn[KMG]#ss[KMG]
971 [KNL,ACPI] Mark specific memory as ACPI data.
972 Region of memory to be used, from ss to ss+nn.
974 memmap=nn[KMG]$ss[KMG]
975 [KNL,ACPI] Mark specific memory as reserved.
976 Region of memory to be used, from ss to ss+nn.
978 meye.*= [HW] Set MotionEye Camera parameters
979 See Documentation/video4linux/meye.txt.
984 [KNL,SMP] debug: override scheduler migration costs
985 Format: <level-1-usecs>,<level-2-usecs>,...
986 This debugging option can be used to override the
987 default scheduler migration cost matrix. The numbers
988 are indexed by 'CPU domain distance'.
989 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
990 box will set up an intra-core migration cost of
991 1 msec, an inter-core migration cost of 2 msecs,
992 and an inter-node migration cost of 3 msecs.
994 WARNING: using the wrong values here can break
995 scheduler performance, so it's only for scheduler
996 development purposes, not production environments.
999 [KNL,SMP] migration cost auto-detect verbosity
1001 If a system's migration matrix reported at bootup
1002 seems erroneous then this option can be used to
1003 increase verbosity of the detection process.
1004 We default to 0 (no extra messages), 1 will print
1005 some more information, and 2 will be really
1006 verbose (probably only useful if you also have a
1007 serial console attached to the system).
1010 [KNL,SMP] multiply/divide migration costs by a factor
1012 This debug option can be used to proportionally
1013 increase or decrease the auto-detected migration
1014 costs for all entries of the migration matrix.
1015 E.g. migration_factor=150 will increase migration
1016 costs by 50%. (and thus the scheduler will be less
1017 eager migrating cache-hot tasks)
1018 migration_factor=80 will decrease migration costs
1019 by 20%. (thus the scheduler will be more eager to
1022 WARNING: using the wrong values here can break
1023 scheduler performance, so it's only for scheduler
1024 development purposes, not production environments.
1027 [MOUSE] Maximum time between finger touching and
1028 leaving touchpad surface for touch to be considered
1029 a tap and be reported as a left button click (for
1030 touchpads working in absolute mode only).
1032 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1033 reporting absolute coordinates, such as tablets
1034 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1035 reporting absolute coordinates, such as tablets
1040 MTD_Partition= [MTD]
1041 Format: <name>,<region-number>,<size>,<offset>
1043 MTD_Region= [MTD] Format:
1044 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1047 See drivers/mtd/cmdline.c.
1049 mtouchusb.raw_coordinates=
1050 [HW] Make the MicroTouch USB driver use raw coordinates
1051 ('y', default) or cooked coordinates ('n')
1053 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1056 See header of drivers/scsi/NCR_D700.c.
1060 ncr53c400= [HW,SCSI]
1062 ncr53c400a= [HW,SCSI]
1064 ncr53c406a= [HW,SCSI]
1066 ncr53c8xx= [HW,SCSI]
1068 netdev= [NET] Network devices parameters
1069 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1070 Note that mem_start is often overloaded to mean
1071 something different and driver-specific.
1072 This usage is only documented in each driver source
1076 See Documentation/nfsroot.txt.
1078 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1079 See Documentation/nfsroot.txt.
1081 nfs.callback_tcpport=
1082 [NFS] set the TCP port on which the NFSv4 callback
1083 channel should listen.
1085 nfs.idmap_cache_timeout=
1086 [NFS] set the maximum lifetime for idmapper cache
1089 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1091 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1092 emulation library even if a 387 maths coprocessor
1095 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1099 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1100 the slab allocator. Saves per-node memory, but will
1101 impact performance on real NUMA hardware.
1105 noapic [SMP,APIC] Tells the kernel to not make use of any
1106 IOAPICs that may be present in the system.
1108 noasync [HW,M68K] Disables async and sync negotiation for
1111 nobats [PPC] Do not use BATs for mapping kernel lowmem
1112 on "Classic" PPC cores.
1116 nodelayacct [KNL] Disable per-task delay accounting
1118 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1122 noexec [IA-32,X86-64]
1123 noexec=on: enable non-executable mappings (default)
1124 noexec=off: disable nn-executable mappings
1126 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1127 register save and restore. The kernel will only save
1128 legacy floating-point registers on task switch.
1132 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1133 instruction doesn't work correctly and not to
1136 nohalt [IA-64] Tells the kernel not to use the power saving
1137 function PAL_HALT_LIGHT when idle. This increases
1138 power-consumption. On the positive side, it reduces
1139 interrupt wake-up latency, which may improve performance
1140 in certain environments such as networked servers or
1143 nohz= [KNL] Boottime enable/disable dynamic ticks
1144 Valid arguments: on, off
1147 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1149 noirqdebug [IA-32] Disables the code which attempts to detect and
1150 disable unhandled interrupt sources.
1152 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1153 broken timer IRQ sources.
1155 noisapnp [ISAPNP] Disables ISA PnP code.
1157 noinitrd [RAM] Tells the kernel not to load any configured
1162 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1164 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1166 noltlbs [PPC] Do not use large page/tlb entries for kernel
1167 lowmem mapping on PPC40x.
1169 nomca [IA-64] Disable machine check abort handling
1171 nomce [IA-32] Machine Check Exception
1173 noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
1175 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1176 with UP alternatives
1178 noresidual [PPC] Don't use residual data on PReP machines.
1180 noresume [SWSUSP] Disables resume and restores original swap
1183 no-scroll [VGA] Disables scrollback.
1184 This is required for the Braillex ib80-piezo Braille
1185 reader made by F.H. Papenmeier (Germany).
1189 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1191 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1193 nosync [HW,M68K] Disables sync negotiation for all devices.
1195 notsc [BUGS=IA-32] Disable Time Stamp Counter
1197 nousb [USB] Disable the USB subsystem
1201 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1206 opl3sa2= [HW,OSS] Format:
1207 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1209 oprofile.timer= [HW]
1210 Use timer interrupt instead of performance counters
1215 osst= [HW,SCSI] SCSI Tape Driver
1216 Format: <buffer_size>,<write_threshold>
1217 See also Documentation/scsi/st.txt.
1219 panic= [KNL] Kernel behaviour on panic
1222 parkbd.port= [HW] Parallel port number the keyboard adapter is
1223 connected to, default is 0.
1225 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1226 0 for XT, 1 for AT (default is AT).
1229 parport= [HW,PPT] Specify parallel ports. 0 disables.
1230 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1231 Use 'auto' to force the driver to use any
1232 IRQ/DMA settings detected (the default is to
1233 ignore detected IRQ/DMA settings because of
1234 possible conflicts). You can specify the base
1235 address, IRQ, and DMA settings; IRQ and DMA
1236 should be numbers, or 'auto' (for using detected
1237 settings on that particular port), or 'nofifo'
1238 (to avoid using a FIFO even if it is detected).
1239 Parallel ports are assigned in the order they
1240 are specified on the command line, starting
1243 parport_init_mode= [HW,PPT]
1244 Configure VIA parallel port to operate in
1245 a specific mode. This is necessary on Pegasos
1246 computer where firmware has no options for setting
1247 up parallel port mode and sets it to spp.
1248 Currently this function knows 686a and 8231 chips.
1249 Format: [spp|ps2|epp|ecp|ecpepp]
1251 pas2= [HW,OSS] Format:
1252 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1255 See header of drivers/scsi/pas16.c.
1258 Halt all CPUs after the first oops has been printed for
1259 the specified number of seconds. This is to be used if
1260 your oopses keep scrolling off the screen.
1265 See header of drivers/block/paride/pcd.c.
1266 See also Documentation/paride.txt.
1268 pci=option[,option...] [PCI] various PCI subsystem options:
1269 off [IA-32] don't probe for the PCI bus
1270 bios [IA-32] force use of PCI BIOS, don't access
1271 the hardware directly. Use this if your machine
1272 has a non-standard PCI host bridge.
1273 nobios [IA-32] disallow use of PCI BIOS, only direct
1274 hardware access methods are allowed. Use this
1275 if you experience crashes upon bootup and you
1276 suspect they are caused by the BIOS.
1277 conf1 [IA-32] Force use of PCI Configuration
1279 conf2 [IA-32] Force use of PCI Configuration
1281 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1283 nomsi [MSI] If the PCI_MSI kernel config parameter is
1284 enabled, this kernel boot option can be used to
1285 disable the use of MSI interrupts system-wide.
1286 nosort [IA-32] Don't sort PCI devices according to
1287 order given by the PCI BIOS. This sorting is
1288 done to get a device order compatible with
1290 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1291 routing table. These calls are known to be buggy
1292 on several machines and they hang the machine
1293 when used, but on other computers it's the only
1294 way to get the interrupt routing table. Try
1295 this option if the kernel is unable to allocate
1296 IRQs or discover secondary PCI buses on your
1298 rom [IA-32] Assign address space to expansion ROMs.
1299 Use with caution as certain devices share
1300 address decoders between ROMs and other
1302 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1303 assigned automatically to PCI devices. You can
1304 make the kernel exclude IRQs of your ISA cards
1306 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1307 of the PIRQ table (normally generated
1308 by the BIOS) if it is outside the
1309 F0000h-100000h range.
1310 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1311 useful if the kernel is unable to find your
1312 secondary buses and you want to tell it
1313 explicitly which ones they are.
1314 assign-busses [IA-32] Always assign all PCI bus
1315 numbers ourselves, overriding
1316 whatever the firmware may have done.
1317 usepirqmask [IA-32] Honor the possible IRQ mask stored
1318 in the BIOS $PIR table. This is needed on
1319 some systems with broken BIOSes, notably
1320 some HP Pavilion N5400 and Omnibook XE3
1321 notebooks. This will have no effect if ACPI
1322 IRQ routing is enabled.
1323 noacpi [IA-32] Do not use ACPI for IRQ routing
1324 or for PCI scanning.
1325 routeirq Do IRQ routing for all PCI devices.
1326 This is normally done in pci_enable_device(),
1327 so this option is a temporary workaround
1328 for broken drivers that don't call it.
1329 firmware [ARM] Do not re-enumerate the bus but instead
1330 just use the configuration from the
1331 bootloader. This is currently used on
1332 IXP2000 systems where the bus has to be
1333 configured a certain way for adjunct CPUs.
1334 noearly [X86] Don't do any early type 1 scanning.
1335 This might help on some broken boards which
1336 machine check when some devices' config space
1337 is read. But various workarounds are disabled
1338 and some IOMMU drivers will not work.
1339 bfsort Sort PCI devices into breadth-first order.
1340 This sorting is done to get a device
1341 order compatible with older (<= 2.4) kernels.
1342 nobfsort Don't sort PCI devices into breadth-first order.
1343 cbiosize=nn[KMG] The fixed amount of bus space which is
1344 reserved for the CardBus bridge's IO window.
1345 The default value is 256 bytes.
1346 cbmemsize=nn[KMG] The fixed amount of bus space which is
1347 reserved for the CardBus bridge's memory
1348 window. The default value is 64 megabytes.
1350 pcmv= [HW,PCMCIA] BadgePAD 4
1353 See Documentation/paride.txt.
1355 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1358 See arch/parisc/kernel/pdc_chassis.c
1361 See Documentation/paride.txt.
1364 See Documentation/paride.txt.
1366 pirq= [SMP,APIC] Manual mp-table setup
1367 See Documentation/i386/IO-APIC.txt.
1369 plip= [PPT,NET] Parallel port network link
1370 Format: { parport<nr> | timid | 0 }
1371 See also Documentation/parport.txt.
1377 { on | off | curr | res | no-curr | no-res }
1380 [ISAPNP] Exclude IRQs for the autoconfiguration
1383 [ISAPNP] Exclude DMAs for the autoconfiguration
1385 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1386 Ranges are in pairs (I/O port base and size).
1389 [ISAPNP] Exclude memory regions for the
1391 Ranges are in pairs (memory base and size).
1393 profile= [KNL] Enable kernel profiling via /proc/profile
1394 Format: [schedule,]<number>
1395 Param: "schedule" - profile schedule points.
1396 Param: <number> - step/bucket size as a power of 2 for
1397 statistical time based profiling.
1398 Param: "sleep" - profile D-state sleeping (millisecs)
1400 processor.max_cstate= [HW,ACPI]
1401 Limit processor to maximum C-state
1402 max_cstate=9 overrides any DMI blacklist limit.
1404 processor.nocst [HW,ACPI]
1405 Ignore the _CST method to determine C-states,
1406 instead using the legacy FADT method
1408 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1410 See Documentation/ramdisk.txt.
1412 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1413 probe for; one of (bare|imps|exps|lifebook|any).
1414 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1416 psmouse.resetafter= [HW,MOUSE]
1417 Try to reset the device after so many bad packets
1420 [HW,MOUSE] Set desired mouse resolution, in dpi.
1421 psmouse.smartscroll=
1422 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1423 0 = disabled, 1 = enabled (default).
1425 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1427 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1430 See Documentation/paride.txt.
1432 quiet [KNL] Disable most log messages
1437 See Documentation/md.txt.
1439 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1440 See Documentation/ramdisk.txt.
1442 ramdisk_blocksize= [RAM]
1443 See Documentation/ramdisk.txt.
1445 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1446 New name for the ramdisk parameter.
1447 See Documentation/ramdisk.txt.
1449 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1450 RCU callbacks to process in one batch.
1452 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1453 RCU callbacks over which batch limiting is disabled.
1455 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1456 RCU callbacks below which batch limiting is re-enabled.
1460 Run specified binary instead of /init from the ramdisk,
1461 used for early userspace startup. See initrd.
1463 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1464 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1465 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1467 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1471 Reserves a hole at the top of the kernel virtual
1474 reset_devices [KNL] Force drivers to reset the underlying device
1475 during initialization.
1478 Specify the partition device for software suspend
1480 resume_offset= [SWSUSP]
1481 Specify the offset from the beginning of the partition
1482 given by "resume=" at which the swap header is located,
1483 in <PAGE_SIZE> units (needed only for swap files).
1484 See Documentation/power/swsusp-and-swap-files.txt
1486 retain_initrd [RAM] Keep initrd memory after extraction
1488 rhash_entries= [KNL,NET]
1489 Set number of hash buckets for route cache
1491 riscom8= [HW,SERIAL]
1492 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1494 ro [KNL] Mount root device read-only on boot
1496 root= [KNL] Root filesystem
1498 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1499 mount the root filesystem
1501 rootflags= [KNL] Set root filesystem mount option string
1503 rootfstype= [KNL] Set root filesystem type
1505 rw [KNL] Mount root device read-write on boot
1507 S [KNL] Run init in single mode
1510 See drivers/net/irda/sa1100_ir.c.
1513 Format: <io>,<irq>,<dma>,<dma2>
1515 sbni= [NET] Granch SBNI12 leased line adapter
1517 sbpcd= [HW,CD] Soundblaster CD adapter
1519 See a comment before function sbpcd_setup() in
1520 drivers/cdrom/sbpcd.c.
1522 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1523 Format: <io>[,<timeout>[,<isapnp>]]
1525 scsi_debug_*= [SCSI]
1526 See drivers/scsi/scsi_debug.c.
1528 scsi_default_dev_flags=
1529 [SCSI] SCSI default device flags
1532 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1533 Format: <vendor>:<model>:<flags>
1534 (flags are integer value)
1536 scsi_logging= [SCSI]
1538 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1539 discovered. async scans them in kernel threads,
1540 allowing boot to proceed. none ignores them, expecting
1541 user space to do the scan.
1543 selinux [SELINUX] Disable or enable SELinux at boot time.
1544 Format: { "0" | "1" }
1545 See security/selinux/Kconfig help text.
1548 Default value is set via kernel config option.
1549 If enabled at boot time, /selinux/disable can be used
1550 later to disable prior to initial policy load.
1552 selinux_compat_net =
1553 [SELINUX] Set initial selinux_compat_net flag value.
1554 Format: { "0" | "1" }
1555 0 -- use new secmark-based packet controls
1556 1 -- use legacy packet controls
1557 Default value is 0 (preferred).
1558 Value can be changed at runtime via
1559 /selinux/compat_net.
1561 serialnumber [BUGS=IA-32]
1563 sg_def_reserved_size= [SCSI]
1566 Maximal number of shapers.
1569 See header of drivers/scsi/sim710.c.
1575 Format: <io>,<irq>,<dma>
1576 See header of drivers/cdrom/sjcd.c.
1581 Format: <io1>[,<io2>[,...,<io8>]]
1583 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1584 attempt to substitute SMP alternatives once at boot.
1586 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1587 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1588 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1589 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1590 smsc-ircc2.ircc_irq= [HW] IRQ line
1591 smsc-ircc2.ircc_dma= [HW] DMA channel
1592 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1593 0: Toshiba Satellite 1800 (GP data pin select)
1594 1: Fast pin select (default)
1597 snd-ad1816a= [HW,ALSA]
1599 snd-ad1848= [HW,ALSA]
1601 snd-ali5451= [HW,ALSA]
1603 snd-als100= [HW,ALSA]
1605 snd-als4000= [HW,ALSA]
1607 snd-azt2320= [HW,ALSA]
1609 snd-cmi8330= [HW,ALSA]
1611 snd-cmipci= [HW,ALSA]
1613 snd-cs4231= [HW,ALSA]
1615 snd-cs4232= [HW,ALSA]
1617 snd-cs4236= [HW,ALSA]
1619 snd-cs4281= [HW,ALSA]
1621 snd-cs46xx= [HW,ALSA]
1623 snd-dt019x= [HW,ALSA]
1625 snd-dummy= [HW,ALSA]
1627 snd-emu10k1= [HW,ALSA]
1629 snd-ens1370= [HW,ALSA]
1631 snd-ens1371= [HW,ALSA]
1633 snd-es968= [HW,ALSA]
1635 snd-es1688= [HW,ALSA]
1637 snd-es18xx= [HW,ALSA]
1639 snd-es1938= [HW,ALSA]
1641 snd-es1968= [HW,ALSA]
1643 snd-fm801= [HW,ALSA]
1645 snd-gusclassic= [HW,ALSA]
1647 snd-gusextreme= [HW,ALSA]
1649 snd-gusmax= [HW,ALSA]
1653 snd-ice1712= [HW,ALSA]
1655 snd-intel8x0= [HW,ALSA]
1657 snd-interwave= [HW,ALSA]
1662 snd-korg1212= [HW,ALSA]
1664 snd-maestro3= [HW,ALSA]
1666 snd-mpu401= [HW,ALSA]
1668 snd-mtpav= [HW,ALSA]
1670 snd-nm256= [HW,ALSA]
1672 snd-opl3sa2= [HW,ALSA]
1680 snd-opti93x= [HW,ALSA]
1684 snd-rme32= [HW,ALSA]
1686 snd-rme96= [HW,ALSA]
1688 snd-rme9652= [HW,ALSA]
1694 snd-sbawe= [HW,ALSA]
1696 snd-serial= [HW,ALSA]
1698 snd-sgalaxy= [HW,ALSA]
1700 snd-sonicvibes= [HW,ALSA]
1705 snd-sun-cs4231= [HW,ALSA]
1707 snd-trident= [HW,ALSA]
1709 snd-usb-audio= [HW,ALSA,USB]
1711 snd-via82xx= [HW,ALSA]
1713 snd-virmidi= [HW,ALSA]
1715 snd-wavefront= [HW,ALSA]
1717 snd-ymfpci= [HW,ALSA]
1720 Format: <io>[,<irq>]
1722 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1723 See Documentation/sonypi.txt
1725 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1726 See Documentation/specialix.txt.
1728 spia_io_base= [HW,MTD]
1734 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1736 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1737 See Documentation/scsi/st.txt.
1740 See header of drivers/scsi/seagate.c.
1744 Set the STI (builtin display/keyboard on the HP-PARISC
1745 machines) console (graphic card) which should be used
1746 as the initial boot-console.
1747 See also comment in drivers/video/console/sticore.c.
1750 See comment in drivers/video/console/sticore.c.
1753 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1757 Control how the NFS server code allocates CPUs to
1758 service thread pools. Depending on how many NICs
1759 you have and where their interrupts are bound, this
1760 option will affect which CPUs will do NFS serving.
1761 Note: this parameter cannot be changed while the
1762 NFS server is running.
1764 auto the server chooses an appropriate mode
1765 automatically using heuristics
1766 global a single global pool contains all CPUs
1767 percpu one pool for each CPU
1768 pernode one pool for each NUMA node (equivalent
1769 to global on non-NUMA machines)
1771 swiotlb= [IA-64] Number of I/O TLB slabs
1775 sym53c416= [HW,SCSI]
1776 See header of drivers/scsi/sym53c416.c.
1778 sysrq_always_enabled
1780 Ignore sysrq setting - this boot parameter will
1781 neutralize any effect of /proc/sys/kernel/sysrq.
1782 Useful for debugging.
1785 See header of drivers/scsi/t128.c.
1789 thash_entries= [KNL,NET]
1790 Set number of hash buckets for TCP connection
1792 time Show timing data prefixed to each printk message line
1794 clocksource= [GENERIC_TIME] Override the default clocksource
1795 Override the default clocksource and use the clocksource
1796 with the name specified.
1798 tipar.timeout= [HW,PPT]
1799 Set communications timeout in tenths of a second
1802 tipar.delay= [HW,PPT]
1803 Set inter-bit delay in microseconds (default 10).
1806 See header of drivers/scsi/seagate.c.
1809 See comment before function dc390_setup() in
1810 drivers/scsi/tmscsim.c.
1814 trix= [HW,OSS] MediaTrix AudioTrix Pro
1816 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1818 tsdev.xres= [TS] Horizontal screen resolution.
1819 tsdev.yres= [TS] Vertical screen resolution.
1821 turbografx.map[2|3]= [HW,JOY]
1822 TurboGraFX parallel port interface
1824 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1825 See also Documentation/input/joystick-parport.txt
1827 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1828 See header of drivers/scsi/u14-34f.c.
1837 [USB] Ignore overcurrent events (default N).
1838 Some badly-designed motherboards generate lots of
1839 bogus events, for ports that aren't wired to
1840 anything. Set this parameter to avoid log spamming.
1841 Note that genuine overcurrent events won't be
1844 usbcore.autosuspend=
1845 [USB] The autosuspend time delay (in seconds) used
1846 for newly-detected USB devices (default 2). This
1847 is the time required before an idle device will be
1848 autosuspended. Devices for which the delay is set
1849 to a negative value won't be autosuspended at all.
1852 [USBHID] The interval which mice are to be polled at.
1855 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1856 vdso=1: enable VDSO (default)
1857 vdso=0: disable VDSO mapping
1859 video= [FB] Frame buffer configuration
1860 See Documentation/fb/modedb.txt.
1862 vga= [BOOT,IA-32] Select a particular video mode
1863 See Documentation/i386/boot.txt and
1864 Documentation/svga.txt.
1865 Use vga=ask for menu.
1866 This is actually a boot loader parameter; the value is
1867 passed to the kernel using a special protocol.
1869 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1870 size of <nn>. This can be used to increase the
1871 minimum size (128MB on x86). It can also be used to
1872 decrease the size and leave more room for directly
1875 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1878 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1881 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1884 waveartist= [HW,OSS]
1885 Format: <io>,<irq>,<dma>,<dma2>
1888 See header of drivers/scsi/wd33c93.c.
1891 See header of drivers/scsi/wd7000.c.
1894 See Documentation/watchdog/watchdog.txt.
1896 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1897 xd_geo= See header of drivers/block/xd.c.
1899 xirc2ps_cs= [NET,PCMCIA]
1901 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1903 norandmaps Don't use address space randomization
1904 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1906 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1907 This is useful to get more information why
1908 you got a "dwarf2 unwinder stuck"
1910 ______________________________________________________________________
1914 Add documentation for ALSA options.
1915 Add more DRM drivers.