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] Modify list of supported OS interface strings
174 acpi_osi="string1" # add string1 -- only one string
175 acpi_osi="!string2" # remove built-in string2
176 acpi_osi= # disable all strings
178 acpi_serialize [HW,ACPI] force serialization of AML methods
180 acpi_skip_timer_override [HW,ACPI]
181 Recognize and ignore IRQ0/pin2 Interrupt Override.
182 For broken nForce2 BIOS resulting in XT-PIC timer.
183 acpi_use_timer_override [HW,ACPI}
184 Use timer override. For some broken Nvidia NF5 boards
185 that require a timer override, but don't have
188 acpi.debug_layer= [HW,ACPI]
190 Each bit of the <int> indicates an ACPI debug layer,
191 1: enable, 0: disable. It is useful for boot time
192 debugging. After system has booted up, it can be set
193 via /sys/module/acpi/parameters/debug_layer.
194 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
195 Available bits (add the numbers together) to enable debug output
196 for specific parts of the ACPI subsystem:
197 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
198 0x10 namespace 0x20 parser 0x40 dispatcher
199 0x80 executer 0x100 resources 0x200 acpica debugger
200 0x400 os services 0x800 acpica disassembler.
201 The number can be in decimal or prefixed with 0x in hex.
202 Warning: Many of these options can produce a lot of
203 output and make your system unusable. Be very careful.
205 acpi.debug_level= [HW,ACPI]
207 Each bit of the <int> indicates an ACPI debug level,
208 1: enable, 0: disable. It is useful for boot time
209 debugging. After system has booted up, it can be set
210 via /sys/module/acpi/parameters/debug_level.
211 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
212 Available bits (add the numbers together) to enable different
213 debug output levels of the ACPI subsystem:
214 0x01 error 0x02 warn 0x04 init 0x08 debug object
215 0x10 info 0x20 init names 0x40 parse 0x80 load
216 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
217 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
218 0x10000 resources 0x20000 user requests 0x40000 package.
219 The number can be in decimal or prefixed with 0x in hex.
220 Warning: Many of these options can produce a lot of
221 output and make your system unusable. Be very careful.
224 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
226 acpi_pm_good [IA-32,X86-64]
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
231 enable_timer_pin_1 [i386,x86-64]
232 Enable PIN 1 of APIC timer
233 Can be useful to work around chipset bugs
234 (in particular on some ATI chipsets).
235 The kernel tries to set a reasonable default.
237 disable_timer_pin_1 [i386,x86-64]
238 Disable PIN 1 of APIC timer
239 Can be useful to work around chipset bugs.
242 Format: <io>,<irq>,<dma>,<dma2>
243 See also Documentation/sound/oss/AD1816.
246 Format: <io>,<irq>,<dma>,<dma2>,<type>
252 See header of drivers/scsi/advansys.c.
254 advwdt= [HW,WDT] Advantech WDT
255 Format: <iostart>,<iostop>
257 aedsp16= [HW,OSS] Audio Excel DSP 16
258 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
259 See also header of sound/oss/aedsp16.c.
262 See Documentation/scsi/aha152x.txt.
265 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
268 See Documentation/scsi/aic7xxx.txt.
271 See Documentation/scsi/aic79xx.txt.
273 amijoy.map= [HW,JOY] Amiga joystick support
274 Map of devices attached to JOY0DAT and JOY1DAT
276 See also Documentation/kernel/input/joystick.txt
278 analog.map= [HW,JOY] Analog joystick and gamepad support
279 Specifies type or capabilities of an analog joystick
280 connected to one of 16 gameports
281 Format: <type1>,<type2>,..<type16>
284 Power management functions (SPARCstation-4/5 + deriv.)
286 Disable APC CPU standby support. SPARCstation-Fox does
287 not play well with APC CPU idle - disable it if you have
288 APC and your system crashes randomly.
290 apic= [APIC,i386] Change the output verbosity whilst booting
291 Format: { quiet (default) | verbose | debug }
292 Change the amount of debugging information output
293 when initialising the APIC and IO-APIC components.
295 apm= [APM] Advanced Power Management
296 See header of arch/i386/kernel/apm.c.
301 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
302 Format: <io>,<irq>,<nodeID>
306 atarimouse= [HW,MOUSE] Atari Mouse
308 atascsi= [HW,SCSI] Atari SCSI
310 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
311 EzKey and similar keyboards
313 atkbd.reset= [HW] Reset keyboard during initialization
315 atkbd.set= [HW] Select keyboard code set
316 Format: <int> (2 = AT (default), 3 = PS/2)
318 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
321 atkbd.softraw= [HW] Choose between synthetic and real raw mode
322 Format: <bool> (0 = real, 1 = synthetic (default))
324 atkbd.softrepeat= [HW]
325 Use software keyboard repeat
329 aztcd= [HW,CD] Aztech CD268 CDROM driver
330 Format: <io>,0x79 (?)
332 baycom_epp= [HW,AX25]
335 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
337 See header of drivers/net/hamradio/baycom_par.c.
339 baycom_ser_fdx= [HW,AX25]
340 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
341 Format: <io>,<irq>,<mode>[,<baud>]
342 See header of drivers/net/hamradio/baycom_ser_fdx.c.
344 baycom_ser_hdx= [HW,AX25]
345 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
346 Format: <io>,<irq>,<mode>
347 See header of drivers/net/hamradio/baycom_ser_hdx.c.
349 blkmtd_device= [HW,MTD]
355 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
356 bttv.radio= Most important insmod options are available as
358 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
359 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
362 See drivers/scsi/BusLogic.c, comment before function
363 BusLogic_ParseDriverOptions().
365 c101= [NET] Moxa C101 synchronous serial card
367 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
368 Sometimes CPU hardware bugs make them report the cache
369 size incorrectly. The kernel will attempt work arounds
370 to fix known problems, but for some CPUs it is not
371 possible to determine what the correct size should be.
372 This option provides an override for these situations.
375 Format: <io>,<irq>[,PAS]
376 See header of drivers/cdrom/cdu31a.c.
378 chandev= [HW,NET] Generic channel device initialisation
380 checkreqprot [SELINUX] Set initial checkreqprot flag value.
381 Format: { "0" | "1" }
382 See security/selinux/Kconfig help text.
383 0 -- check protection applied by kernel (includes
384 any implied execute protection).
385 1 -- check protection requested by application.
386 Default value is set via a kernel config option.
387 Value can be changed at runtime via
388 /selinux/checkreqprot.
390 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
392 Forces specified clocksource (if available) to be used
393 when calculating gettimeofday(). If specified
394 clocksource is not available, it defaults to PIT.
395 Format: { pit | tsc | cyclone | pmtmr }
397 clocksource= [GENERIC_TIME] Override the default clocksource
399 Override the default clocksource and use the clocksource
400 with the name specified.
401 Some clocksource names to choose from, depending on
403 [all] jiffies (this is the base, fallback clocksource)
405 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
406 pxa_timer,timer3,32k_counter,timer0_1
408 [IA-32] pit,hpet,tsc,vmi-timer;
409 scx200_hrt on Geode; cyclone on IBM x440
417 code_bytes [IA32] How many bytes of object code to print in an
424 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
425 over the 8254 in addition to over the IO-APIC. The
426 kernel tries to set a sensible default.
428 hpet= [IA-32,HPET] option to disable HPET and use PIT.
432 Format: { auto | [<io>,][<irq>] }
434 com20020= [HW,NET] ARCnet - COM20020 chipset
436 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
438 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
442 ARCnet - COM90xx chipset (memory-mapped buffers)
443 Format: <io>[,<irq>[,<memstart>]]
445 condev= [HW,S390] console device
448 console= [KNL] Output console device and options.
450 tty<n> Use the virtual console device <n>.
454 Use the specified serial port. The options are of
455 the form "bbbbpnf", where "bbbb" is the baud rate,
456 "p" is parity ("n", "o", or "e"), "n" is number of
457 bits, and "f" is flow control ("r" for RTS or
458 omit it). Default is "9600n8".
460 See Documentation/serial-console.txt for more
462 Documentation/networking/netconsole.txt for an
465 uart[8250],io,<addr>[,options]
466 uart[8250],mmio,<addr>[,options]
467 Start an early, polled-mode console on the 8250/16550
468 UART at the specified I/O port or MMIO address,
469 switching to the matching ttyS device later. The
470 options are the same as for ttyS, above.
472 earlycon= [KNL] Output early console device and options.
473 uart[8250],io,<addr>[,options]
474 uart[8250],mmio,<addr>[,options]
475 Start an early, polled-mode console on the 8250/16550
476 UART at the specified I/O port or MMIO address.
477 The options are the same as for ttyS, above.
479 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
481 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
484 Format: { parport<nr> | auto | none }
486 crashkernel=nn[KMG]@ss[KMG]
487 [KNL] Reserve a chunk of physical memory to
488 hold a kernel to switch to with kexec on panic.
491 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
496 cs89x0_media= [HW,NET]
497 Format: { rj45 | aui | bnc }
499 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
502 See header of drivers/s390/block/dasd_devmap.c.
504 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
505 (one device per port)
506 Format: <port#>,<type>
507 See also Documentation/input/joystick-parport.txt
509 debug [KNL] Enable kernel debugging (events log level).
512 [KNL] verbose self-tests
514 Print debugging info while doing the locking API
516 We default to 0 (no extra messages), setting it to
517 1 will print _a lot_ more information - normally
518 only useful to kernel developers.
521 Format: <area>[,<node>]
522 See also Documentation/networking/decnet.txt.
525 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
526 Change the default blue palette of the console.
527 This is a 16-member array composed of values
531 Format: <green0>,<green1>,<green2>,...,<green15>
532 Change the default green palette of the console.
533 This is a 16-member array composed of values
537 Format: <red0>,<red1>,<red2>,...,<red15>
538 Change the default red palette of the console.
539 This is a 16-member array composed of values
544 Set system-wide default UTF-8 mode for all tty's.
545 Default is 0 and by setting to 1, it enables UTF-8
546 mode for all newly opened or allocated terminals.
549 Set number of hash buckets for dentry cache.
552 IO parameters + enable/disable command.
554 digiepca= [HW,SERIAL]
555 See drivers/char/README.epca and
556 Documentation/digiepca.txt.
558 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
560 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
562 dmasound= [HW,OSS] Sound subsystem buffers
568 earlyprintk= [IA-32,X86-64,SH]
570 earlyprintk=serial[,ttySn[,baudrate]]
572 Append ",keep" to not disable it when the real console
575 Only vga or serial at a time, not both.
577 Currently only ttyS0 and ttyS1 are supported.
579 Interaction with the standard serial driver is not
582 The VGA output is eventually overwritten by the real
587 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
590 non-0: interrupt mode (default)
597 Format: {"of[f]" | "sk[ipmbr]"}
598 See comment in arch/i386/boot/edd.S
601 Format: <id>,<membase>,<irq>
603 eisa_irq_edge= [PARISC,HW]
604 See header of drivers/parisc/eisa.c.
607 See comment before function elanfreq_setup() in
608 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
611 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
612 See Documentation/block/as-iosched.txt and
613 Documentation/block/deadline-iosched.txt for details.
615 elfcorehdr= [IA-32, X86_64]
616 Specifies physical address of start of kernel core
617 image elf header. Generally kexec loader will
618 pass this option to capture kernel.
619 See Documentation/kdump/kdump.txt for details.
621 enforcing [SELINUX] Set initial enforcing status.
623 See security/selinux/Kconfig help text.
624 0 -- permissive (log only, no denials).
625 1 -- enforcing (deny and log).
627 Value can be changed at runtime via /selinux/enforce.
630 Format: <spdif>,[<nomix>,[<amplifier>]]
631 See also header of sound/oss/es1371.c.
633 ether= [HW,NET] Ethernet cards parameters
634 This option is obsoleted by the "netdev=" option, which
635 has equivalent usage. See its documentation for details.
637 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
642 fail_make_request=[KNL]
643 General fault injection mechanism.
644 Format: <interval>,<probability>,<space>,<times>
645 See also /Documentation/fault-injection/.
648 See header of drivers/scsi/fd_mcs.c.
651 See header of drivers/scsi/fdomain.c.
654 See Documentation/floppy.txt.
657 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
658 support via parallel port (up to 5 devices per port)
659 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
660 See also Documentation/input/joystick-parport.txt
665 See header of drivers/scsi/gdth.c.
667 gpt [EFI] Forces disk with valid GPT signature but
668 invalid Protective MBR to be treated as GPT.
675 hashdist= [KNL,NUMA] Large hashes allocated during boot
676 are distributed across NUMA nodes. Defaults on
677 for IA-64, off otherwise.
678 Format: 0 | 1 (for off | on)
680 hcl= [IA-64] SGI's Hardware Graph compatibility layer
682 hd= [EIDE] (E)IDE hard drive subsystem geometry
683 Format: <cyl>,<head>,<sect>
685 hd?= [HW] (E)IDE subsystem
686 hd?lun= See Documentation/ide.txt.
688 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
689 size of <nn>. This works even on boxes that have no
690 highmem otherwise. This also works to reduce highmem
691 size on bigger boxes.
693 highres= [KNL] Enable/disable high resolution timer mode.
694 Valid parameters: "on", "off"
698 See Documentation/isdn/README.HiSax.
700 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
702 i8042.direct [HW] Put keyboard port into non-translated mode
703 i8042.dumbkbd [HW] Pretend that controller can only read data from
704 keyboard and cannot control its state
705 (Don't attempt to blink the leds)
706 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
707 i8042.nokbd [HW] Don't check/create keyboard port
708 i8042.nomux [HW] Don't check presence of an active multiplexing
710 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
713 [HW] Frequency with which keyboard LEDs should blink
714 when kernel panics (default is 0.5 sec)
715 i8042.reset [HW] Reset the controller during init and cleanup
716 i8042.unlock [HW] Unlock (ignore) the keylock
720 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
721 indicates that the driver is running on unsupported
723 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
724 does not match list of supported models.
726 [HW] Report power status in /proc/i8k
727 (disabled by default)
728 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
731 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
732 See Documentation/mca.txt.
735 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
737 ide= [HW] (E)IDE subsystem
738 Format: ide=nodma or ide=doubler or ide=reverse
739 See Documentation/ide.txt.
741 ide?= [HW] (E)IDE subsystem
742 Format: ide?=noprobe or chipset specific parameters.
743 See Documentation/ide.txt.
745 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
746 See Documentation/ide.txt.
749 Format: idle=poll or idle=mwait
750 Poll forces a polling idle loop that can slightly improves the performance
751 of waking up a idle CPU, but will use a lot of power and make the system
752 run hot. Not recommended.
753 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
754 to not use it because it doesn't save as much power as a normal idle
755 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
758 ignore_loglevel [KNL]
759 Ignore loglevel setting - this will print /all/
760 kernel messages to the console. Useful for debugging.
763 Set number of hash buckets for inode cache.
766 See header of drivers/scsi/in2000.c.
770 Run specified binary instead of /sbin/init as init
773 initcall_debug [KNL] Trace initcalls as they are executed. Useful
774 for working out where the kernel is dying during
777 initrd= [BOOT] Specify the location of the initial ramdisk
779 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
784 io7= [HW] IO7 for Marvel based alpha systems
785 See comment before marvel_specify_io7 in
786 arch/alpha/kernel/core_marvel.c.
789 See Documentation/nfsroot.txt.
791 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
792 See comment before ip2_setup() in drivers/char/ip2.c.
794 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
795 See header of drivers/scsi/ips.c.
797 ports= [IP_VS_FTP] IPVS ftp helper module
799 Up to 8 (IP_VS_APP_MAX_PORTS) ports
801 Format: <port>,<port>....
804 When an interrupt is not handled search all handlers
805 for it. Intended to get systems with badly broken
809 When an interrupt is not handled search all handlers
810 for it. Also check all handlers each timer
811 interrupt. Intended to get systems with badly broken
815 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
817 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
819 <cpu number>,...,<cpu number>
821 <cpu number>-<cpu number> (must be a positive range in ascending order)
823 <cpu number>,...,<cpu number>-<cpu number>
824 This option can be used to specify one or more CPUs
825 to isolate from the general SMP balancing and scheduling
826 algorithms. The only way to move a process onto or off
827 an "isolated" CPU is via the CPU affinity syscalls.
828 <cpu number> begins at 0 and the maximum value is
829 "number of CPUs in system - 1".
831 This option is the preferred way to isolate CPUs. The
832 alternative -- manually setting the CPU mask of all
833 tasks in the system -- can cause problems and
834 suboptimal load balancer performance.
837 Format: <io>,<irq>,<dma>,<setup>
841 js= [HW,JOY] Analog joystick
842 See Documentation/input/joystick.txt.
846 kstack=N [IA-32,X86-64] Print N words from the kernel stack
851 lapic [IA-32,APIC] Enable the local APIC even if BIOS
854 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
857 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
858 Format: addr:<io>,irq:<irq>
860 legacy_serial.force [HW,IA-32,X86-64]
861 Probe for COM ports at legacy addresses even
862 if PNPBIOS or ACPI should describe them. This
863 is for working around firmware defects.
865 llsc*= [IA64] See function print_params() in
866 arch/ia64/sn/kernel/llsc4.c.
868 load_ramdisk= [RAM] List of ramdisks to load from floppy
869 See Documentation/ramdisk.txt.
871 lockd.nlm_grace_period=P [NFS] Assign grace period.
874 lockd.nlm_tcpport=N [NFS] Assign TCP port.
877 lockd.nlm_timeout=T [NFS] Assign timeout value.
880 lockd.nlm_udpport=M [NFS] Assign UDP port.
883 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
886 loglevel= All Kernel Messages with a loglevel smaller than the
887 console loglevel will be printed to the console. It can
888 also be changed with klogd or other programs. The
889 loglevels are defined as follows:
891 0 (KERN_EMERG) system is unusable
892 1 (KERN_ALERT) action must be taken immediately
893 2 (KERN_CRIT) critical conditions
894 3 (KERN_ERR) error conditions
895 4 (KERN_WARNING) warning conditions
896 5 (KERN_NOTICE) normal but significant condition
897 6 (KERN_INFO) informational
898 7 (KERN_DEBUG) debug-level messages
900 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
901 Format: { n | nk | nM }
902 n must be a power of two. The default size
903 is set in the kernel config file.
905 lp=0 [LP] Specify parallel ports to use, e.g,
906 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
907 lp=reset first parallel port). 'lp=0' disables the
908 lp=auto printer driver. 'lp=reset' (which can be
909 specified in addition to the ports) causes
910 attached printers to be reset. Using
911 lp=port1,port2,... specifies the parallel ports
912 to associate lp devices with, starting with
913 lp0. A port specification may be 'none' to skip
914 that lp device, or a parport name such as
915 'parport0'. Specifying 'lp=auto' instead of a
916 port specification list means that device IDs
917 from each port should be examined, to see if
918 an IEEE 1284-compliant printer is attached; if
919 so, the driver will manage that printer.
920 See also header of drivers/char/lp.c.
923 Sets loops_per_jiffy to given constant, thus avoiding
924 time-consuming boot-time autodetection (up to 250 ms per
925 CPU). 0 enables autodetection (default). To determine
926 the correct value for your kernel, boot with normal
927 autodetection and see what value is printed. Note that
928 on SMP systems the preset will be applied to all CPUs,
929 which is likely to cause problems if your CPUs need
930 significantly divergent settings. An incorrect value
931 will cause delays in the kernel to be wrong, leading to
932 unpredictable I/O errors and other breakage. Although
933 unlikely, in the extreme case this might damage your
937 Format: <io>,<irq>,<dma>
939 mac5380= [HW,SCSI] Format:
940 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
942 mac53c9x= [HW,SCSI] Format:
943 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
945 machvec= [IA64] Force the use of a particular machine-vector
946 (machvec) in a generic kernel.
947 Example: machvec=hpzx1_swiotlb
949 max_loop= [LOOP] Maximum number of loopback devices that can
953 maxcpus= [SMP] Maximum number of processors that an SMP kernel
955 Using "nosmp" or "maxcpus=0" will disable SMP
956 entirely (the MPS table probe still happens, though).
957 A command-line option of "maxcpus=<NUM>", where <NUM>
958 is an integer greater than 0, limits the maximum number
959 of CPUs activated in SMP mode to <NUM>.
960 Using "maxcpus=1" on an SMP kernel is the trivial
961 case of an SMP kernel with only one CPU.
963 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
964 equal to this physical address is ignored.
966 max_luns= [SCSI] Maximum number of LUNs to probe.
967 Should be between 1 and 2^32-1.
970 [SCSI] Maximum number of LUNs received.
971 Should be between 1 and 16384.
973 mca-pentium [BUGS=IA-32]
978 Format: <port>,<irq>,<mitsumi_bug_93_wait>
982 mce [IA-32] Machine Check Exception
984 md= [HW] RAID subsystems devices and level
985 See Documentation/md.txt.
988 Format: <first>,<last>
989 Specifies range of consoles to be captured by the MDA.
991 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
992 Amount of memory to be used when the kernel is not able
993 to see the whole system memory or for test.
994 [IA-32] Use together with memmap= to avoid physical
995 address space collisions. Without memmap= PCI devices
996 could be placed at addresses belonging to unused RAM.
998 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
1001 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1002 E820 memory map, as specified by the user.
1003 Such memmap=exactmap lines can be constructed based on
1004 BIOS output or other requirements. See the memmap=nn@ss
1007 memmap=nn[KMG]@ss[KMG]
1008 [KNL] Force usage of a specific region of memory
1009 Region of memory to be used, from ss to ss+nn.
1011 memmap=nn[KMG]#ss[KMG]
1012 [KNL,ACPI] Mark specific memory as ACPI data.
1013 Region of memory to be used, from ss to ss+nn.
1015 memmap=nn[KMG]$ss[KMG]
1016 [KNL,ACPI] Mark specific memory as reserved.
1017 Region of memory to be used, from ss to ss+nn.
1019 meye.*= [HW] Set MotionEye Camera parameters
1020 See Documentation/video4linux/meye.txt.
1025 [MOUSE] Maximum time between finger touching and
1026 leaving touchpad surface for touch to be considered
1027 a tap and be reported as a left button click (for
1028 touchpads working in absolute mode only).
1030 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1031 reporting absolute coordinates, such as tablets
1032 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1033 reporting absolute coordinates, such as tablets
1038 MTD_Partition= [MTD]
1039 Format: <name>,<region-number>,<size>,<offset>
1041 MTD_Region= [MTD] Format:
1042 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1045 See drivers/mtd/cmdline.c.
1047 mtouchusb.raw_coordinates=
1048 [HW] Make the MicroTouch USB driver use raw coordinates
1049 ('y', default) or cooked coordinates ('n')
1051 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1054 See header of drivers/scsi/NCR_D700.c.
1058 ncr53c400= [HW,SCSI]
1060 ncr53c400a= [HW,SCSI]
1062 ncr53c406a= [HW,SCSI]
1064 ncr53c8xx= [HW,SCSI]
1066 netdev= [NET] Network devices parameters
1067 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1068 Note that mem_start is often overloaded to mean
1069 something different and driver-specific.
1070 This usage is only documented in each driver source
1074 See Documentation/nfsroot.txt.
1076 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1077 See Documentation/nfsroot.txt.
1079 nfs.callback_tcpport=
1080 [NFS] set the TCP port on which the NFSv4 callback
1081 channel should listen.
1083 nfs.idmap_cache_timeout=
1084 [NFS] set the maximum lifetime for idmapper cache
1087 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1089 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1090 emulation library even if a 387 maths coprocessor
1093 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1097 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1098 caches in the slab allocator. Saves per-node memory,
1099 but will impact performance.
1103 noapic [SMP,APIC] Tells the kernel to not make use of any
1104 IOAPICs that may be present in the system.
1106 noasync [HW,M68K] Disables async and sync negotiation for
1109 nobats [PPC] Do not use BATs for mapping kernel lowmem
1110 on "Classic" PPC cores.
1114 nodelayacct [KNL] Disable per-task delay accounting
1116 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1120 noexec [IA-32,X86-64]
1121 noexec=on: enable non-executable mappings (default)
1122 noexec=off: disable nn-executable mappings
1124 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1125 register save and restore. The kernel will only save
1126 legacy floating-point registers on task switch.
1130 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1131 instruction doesn't work correctly and not to
1134 nohalt [IA-64] Tells the kernel not to use the power saving
1135 function PAL_HALT_LIGHT when idle. This increases
1136 power-consumption. On the positive side, it reduces
1137 interrupt wake-up latency, which may improve performance
1138 in certain environments such as networked servers or
1141 nohz= [KNL] Boottime enable/disable dynamic ticks
1142 Valid arguments: on, off
1145 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1147 noirqdebug [IA-32] Disables the code which attempts to detect and
1148 disable unhandled interrupt sources.
1150 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1151 broken timer IRQ sources.
1153 noisapnp [ISAPNP] Disables ISA PnP code.
1155 noinitrd [RAM] Tells the kernel not to load any configured
1160 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1162 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1164 noltlbs [PPC] Do not use large page/tlb entries for kernel
1165 lowmem mapping on PPC40x.
1167 nomca [IA-64] Disable machine check abort handling
1169 nomce [IA-32] Machine Check Exception
1171 noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
1173 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1174 with UP alternatives
1176 noresidual [PPC] Don't use residual data on PReP machines.
1178 noresume [SWSUSP] Disables resume and restores original swap
1181 no-scroll [VGA] Disables scrollback.
1182 This is required for the Braillex ib80-piezo Braille
1183 reader made by F.H. Papenmeier (Germany).
1187 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1189 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1191 nosync [HW,M68K] Disables sync negotiation for all devices.
1193 notsc [BUGS=IA-32] Disable Time Stamp Counter
1195 nousb [USB] Disable the USB subsystem
1199 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1200 one of ['zone', 'node', 'default'] can be specified
1201 This can be set from sysctl after boot.
1202 See Documentation/sysctl/vm.txt for details.
1204 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1209 opl3sa2= [HW,OSS] Format:
1210 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1212 oprofile.timer= [HW]
1213 Use timer interrupt instead of performance counters
1218 osst= [HW,SCSI] SCSI Tape Driver
1219 Format: <buffer_size>,<write_threshold>
1220 See also Documentation/scsi/st.txt.
1222 panic= [KNL] Kernel behaviour on panic
1225 parkbd.port= [HW] Parallel port number the keyboard adapter is
1226 connected to, default is 0.
1228 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1229 0 for XT, 1 for AT (default is AT).
1232 parport= [HW,PPT] Specify parallel ports. 0 disables.
1233 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1234 Use 'auto' to force the driver to use any
1235 IRQ/DMA settings detected (the default is to
1236 ignore detected IRQ/DMA settings because of
1237 possible conflicts). You can specify the base
1238 address, IRQ, and DMA settings; IRQ and DMA
1239 should be numbers, or 'auto' (for using detected
1240 settings on that particular port), or 'nofifo'
1241 (to avoid using a FIFO even if it is detected).
1242 Parallel ports are assigned in the order they
1243 are specified on the command line, starting
1246 parport_init_mode= [HW,PPT]
1247 Configure VIA parallel port to operate in
1248 a specific mode. This is necessary on Pegasos
1249 computer where firmware has no options for setting
1250 up parallel port mode and sets it to spp.
1251 Currently this function knows 686a and 8231 chips.
1252 Format: [spp|ps2|epp|ecp|ecpepp]
1254 pas2= [HW,OSS] Format:
1255 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1258 See header of drivers/scsi/pas16.c.
1261 Halt all CPUs after the first oops has been printed for
1262 the specified number of seconds. This is to be used if
1263 your oopses keep scrolling off the screen.
1268 See header of drivers/block/paride/pcd.c.
1269 See also Documentation/paride.txt.
1271 pci=option[,option...] [PCI] various PCI subsystem options:
1272 off [IA-32] don't probe for the PCI bus
1273 bios [IA-32] force use of PCI BIOS, don't access
1274 the hardware directly. Use this if your machine
1275 has a non-standard PCI host bridge.
1276 nobios [IA-32] disallow use of PCI BIOS, only direct
1277 hardware access methods are allowed. Use this
1278 if you experience crashes upon bootup and you
1279 suspect they are caused by the BIOS.
1280 conf1 [IA-32] Force use of PCI Configuration
1282 conf2 [IA-32] Force use of PCI Configuration
1284 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1286 nomsi [MSI] If the PCI_MSI kernel config parameter is
1287 enabled, this kernel boot option can be used to
1288 disable the use of MSI interrupts system-wide.
1289 nosort [IA-32] Don't sort PCI devices according to
1290 order given by the PCI BIOS. This sorting is
1291 done to get a device order compatible with
1293 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1294 routing table. These calls are known to be buggy
1295 on several machines and they hang the machine
1296 when used, but on other computers it's the only
1297 way to get the interrupt routing table. Try
1298 this option if the kernel is unable to allocate
1299 IRQs or discover secondary PCI buses on your
1301 rom [IA-32] Assign address space to expansion ROMs.
1302 Use with caution as certain devices share
1303 address decoders between ROMs and other
1305 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1306 assigned automatically to PCI devices. You can
1307 make the kernel exclude IRQs of your ISA cards
1309 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1310 of the PIRQ table (normally generated
1311 by the BIOS) if it is outside the
1312 F0000h-100000h range.
1313 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1314 useful if the kernel is unable to find your
1315 secondary buses and you want to tell it
1316 explicitly which ones they are.
1317 assign-busses [IA-32] Always assign all PCI bus
1318 numbers ourselves, overriding
1319 whatever the firmware may have done.
1320 usepirqmask [IA-32] Honor the possible IRQ mask stored
1321 in the BIOS $PIR table. This is needed on
1322 some systems with broken BIOSes, notably
1323 some HP Pavilion N5400 and Omnibook XE3
1324 notebooks. This will have no effect if ACPI
1325 IRQ routing is enabled.
1326 noacpi [IA-32] Do not use ACPI for IRQ routing
1327 or for PCI scanning.
1328 routeirq Do IRQ routing for all PCI devices.
1329 This is normally done in pci_enable_device(),
1330 so this option is a temporary workaround
1331 for broken drivers that don't call it.
1332 firmware [ARM] Do not re-enumerate the bus but instead
1333 just use the configuration from the
1334 bootloader. This is currently used on
1335 IXP2000 systems where the bus has to be
1336 configured a certain way for adjunct CPUs.
1337 noearly [X86] Don't do any early type 1 scanning.
1338 This might help on some broken boards which
1339 machine check when some devices' config space
1340 is read. But various workarounds are disabled
1341 and some IOMMU drivers will not work.
1342 bfsort Sort PCI devices into breadth-first order.
1343 This sorting is done to get a device
1344 order compatible with older (<= 2.4) kernels.
1345 nobfsort Don't sort PCI devices into breadth-first order.
1346 cbiosize=nn[KMG] The fixed amount of bus space which is
1347 reserved for the CardBus bridge's IO window.
1348 The default value is 256 bytes.
1349 cbmemsize=nn[KMG] The fixed amount of bus space which is
1350 reserved for the CardBus bridge's memory
1351 window. The default value is 64 megabytes.
1353 pcmv= [HW,PCMCIA] BadgePAD 4
1356 See Documentation/paride.txt.
1358 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1361 See arch/parisc/kernel/pdc_chassis.c
1364 See Documentation/paride.txt.
1367 See Documentation/paride.txt.
1369 pirq= [SMP,APIC] Manual mp-table setup
1370 See Documentation/i386/IO-APIC.txt.
1372 plip= [PPT,NET] Parallel port network link
1373 Format: { parport<nr> | timid | 0 }
1374 See also Documentation/parport.txt.
1380 { on | off | curr | res | no-curr | no-res }
1383 [ISAPNP] Exclude IRQs for the autoconfiguration
1386 [ISAPNP] Exclude DMAs for the autoconfiguration
1388 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1389 Ranges are in pairs (I/O port base and size).
1392 [ISAPNP] Exclude memory regions for the
1394 Ranges are in pairs (memory base and size).
1396 profile= [KNL] Enable kernel profiling via /proc/profile
1397 Format: [schedule,]<number>
1398 Param: "schedule" - profile schedule points.
1399 Param: <number> - step/bucket size as a power of 2 for
1400 statistical time based profiling.
1401 Param: "sleep" - profile D-state sleeping (millisecs)
1403 processor.max_cstate= [HW,ACPI]
1404 Limit processor to maximum C-state
1405 max_cstate=9 overrides any DMI blacklist limit.
1407 processor.nocst [HW,ACPI]
1408 Ignore the _CST method to determine C-states,
1409 instead using the legacy FADT method
1411 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1413 See Documentation/ramdisk.txt.
1415 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1416 probe for; one of (bare|imps|exps|lifebook|any).
1417 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1419 psmouse.resetafter= [HW,MOUSE]
1420 Try to reset the device after so many bad packets
1423 [HW,MOUSE] Set desired mouse resolution, in dpi.
1424 psmouse.smartscroll=
1425 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1426 0 = disabled, 1 = enabled (default).
1428 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1430 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1433 See Documentation/paride.txt.
1435 quiet [KNL] Disable most log messages
1440 See Documentation/md.txt.
1442 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1443 See Documentation/ramdisk.txt.
1445 ramdisk_blocksize= [RAM]
1446 See Documentation/ramdisk.txt.
1448 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1449 New name for the ramdisk parameter.
1450 See Documentation/ramdisk.txt.
1452 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1453 RCU callbacks to process in one batch.
1455 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1456 RCU callbacks over which batch limiting is disabled.
1458 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1459 RCU callbacks below which batch limiting is re-enabled.
1463 Run specified binary instead of /init from the ramdisk,
1464 used for early userspace startup. See initrd.
1466 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1467 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1468 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1470 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1474 Reserves a hole at the top of the kernel virtual
1477 reset_devices [KNL] Force drivers to reset the underlying device
1478 during initialization.
1481 Specify the partition device for software suspend
1483 resume_offset= [SWSUSP]
1484 Specify the offset from the beginning of the partition
1485 given by "resume=" at which the swap header is located,
1486 in <PAGE_SIZE> units (needed only for swap files).
1487 See Documentation/power/swsusp-and-swap-files.txt
1489 retain_initrd [RAM] Keep initrd memory after extraction
1491 rhash_entries= [KNL,NET]
1492 Set number of hash buckets for route cache
1494 riscom8= [HW,SERIAL]
1495 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1497 ro [KNL] Mount root device read-only on boot
1499 root= [KNL] Root filesystem
1501 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1502 mount the root filesystem
1504 rootflags= [KNL] Set root filesystem mount option string
1506 rootfstype= [KNL] Set root filesystem type
1508 rw [KNL] Mount root device read-write on boot
1510 S [KNL] Run init in single mode
1513 See drivers/net/irda/sa1100_ir.c.
1516 Format: <io>,<irq>,<dma>,<dma2>
1518 sbni= [NET] Granch SBNI12 leased line adapter
1520 sbpcd= [HW,CD] Soundblaster CD adapter
1522 See a comment before function sbpcd_setup() in
1523 drivers/cdrom/sbpcd.c.
1525 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1526 Format: <io>[,<timeout>[,<isapnp>]]
1528 scsi_debug_*= [SCSI]
1529 See drivers/scsi/scsi_debug.c.
1531 scsi_default_dev_flags=
1532 [SCSI] SCSI default device flags
1535 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1536 Format: <vendor>:<model>:<flags>
1537 (flags are integer value)
1539 scsi_logging= [SCSI]
1541 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1542 discovered. async scans them in kernel threads,
1543 allowing boot to proceed. none ignores them, expecting
1544 user space to do the scan.
1546 selinux [SELINUX] Disable or enable SELinux at boot time.
1547 Format: { "0" | "1" }
1548 See security/selinux/Kconfig help text.
1551 Default value is set via kernel config option.
1552 If enabled at boot time, /selinux/disable can be used
1553 later to disable prior to initial policy load.
1555 selinux_compat_net =
1556 [SELINUX] Set initial selinux_compat_net flag value.
1557 Format: { "0" | "1" }
1558 0 -- use new secmark-based packet controls
1559 1 -- use legacy packet controls
1560 Default value is 0 (preferred).
1561 Value can be changed at runtime via
1562 /selinux/compat_net.
1564 serialnumber [BUGS=IA-32]
1566 sg_def_reserved_size= [SCSI]
1569 Maximal number of shapers.
1572 See header of drivers/scsi/sim710.c.
1578 Format: <io>,<irq>,<dma>
1579 See header of drivers/cdrom/sjcd.c.
1583 slub_debug [MM, SLUB]
1584 Enabling slub_debug allows one to determine the culprit
1585 if slab objects become corrupted. Enabling slub_debug
1586 creates guard zones around objects and poisons objects
1587 when not in use. Also tracks the last alloc / free.
1588 For more information see Documentation/vm/slub.txt.
1590 slub_max_order= [MM, SLUB]
1591 Determines the maximum allowed order for slabs. Setting
1592 this too high may cause fragmentation.
1593 For more information see Documentation/vm/slub.txt.
1595 slub_min_objects= [MM, SLUB]
1596 The minimum objects per slab. SLUB will increase the
1597 slab order up to slub_max_order to generate a
1598 sufficiently big slab to satisfy the number of objects.
1599 The higher the number of objects the smaller the overhead
1601 For more information see Documentation/vm/slub.txt.
1603 slub_min_order= [MM, SLUB]
1604 Determines the mininum page order for slabs. Must be
1605 lower than slub_max_order
1606 For more information see Documentation/vm/slub.txt.
1608 slub_nomerge [MM, SLUB]
1609 Disable merging of slabs of similar size. May be
1610 necessary if there is some reason to distinguish
1611 allocs to different slabs.
1612 For more information see Documentation/vm/slub.txt.
1615 Format: <io1>[,<io2>[,...,<io8>]]
1617 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1618 attempt to substitute SMP alternatives once at boot.
1620 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1621 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1622 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1623 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1624 smsc-ircc2.ircc_irq= [HW] IRQ line
1625 smsc-ircc2.ircc_dma= [HW] DMA channel
1626 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1627 0: Toshiba Satellite 1800 (GP data pin select)
1628 1: Fast pin select (default)
1631 snd-ad1816a= [HW,ALSA]
1633 snd-ad1848= [HW,ALSA]
1635 snd-ali5451= [HW,ALSA]
1637 snd-als100= [HW,ALSA]
1639 snd-als4000= [HW,ALSA]
1641 snd-azt2320= [HW,ALSA]
1643 snd-cmi8330= [HW,ALSA]
1645 snd-cmipci= [HW,ALSA]
1647 snd-cs4231= [HW,ALSA]
1649 snd-cs4232= [HW,ALSA]
1651 snd-cs4236= [HW,ALSA]
1653 snd-cs4281= [HW,ALSA]
1655 snd-cs46xx= [HW,ALSA]
1657 snd-dt019x= [HW,ALSA]
1659 snd-dummy= [HW,ALSA]
1661 snd-emu10k1= [HW,ALSA]
1663 snd-ens1370= [HW,ALSA]
1665 snd-ens1371= [HW,ALSA]
1667 snd-es968= [HW,ALSA]
1669 snd-es1688= [HW,ALSA]
1671 snd-es18xx= [HW,ALSA]
1673 snd-es1938= [HW,ALSA]
1675 snd-es1968= [HW,ALSA]
1677 snd-fm801= [HW,ALSA]
1679 snd-gusclassic= [HW,ALSA]
1681 snd-gusextreme= [HW,ALSA]
1683 snd-gusmax= [HW,ALSA]
1687 snd-ice1712= [HW,ALSA]
1689 snd-intel8x0= [HW,ALSA]
1691 snd-interwave= [HW,ALSA]
1696 snd-korg1212= [HW,ALSA]
1698 snd-maestro3= [HW,ALSA]
1700 snd-mpu401= [HW,ALSA]
1702 snd-mtpav= [HW,ALSA]
1704 snd-nm256= [HW,ALSA]
1706 snd-opl3sa2= [HW,ALSA]
1714 snd-opti93x= [HW,ALSA]
1718 snd-rme32= [HW,ALSA]
1720 snd-rme96= [HW,ALSA]
1722 snd-rme9652= [HW,ALSA]
1728 snd-sbawe= [HW,ALSA]
1730 snd-serial= [HW,ALSA]
1732 snd-sgalaxy= [HW,ALSA]
1734 snd-sonicvibes= [HW,ALSA]
1739 snd-sun-cs4231= [HW,ALSA]
1741 snd-trident= [HW,ALSA]
1743 snd-usb-audio= [HW,ALSA,USB]
1745 snd-via82xx= [HW,ALSA]
1747 snd-virmidi= [HW,ALSA]
1749 snd-wavefront= [HW,ALSA]
1751 snd-ymfpci= [HW,ALSA]
1754 Format: <io>[,<irq>]
1756 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1757 See Documentation/sonypi.txt
1759 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1760 See Documentation/specialix.txt.
1762 spia_io_base= [HW,MTD]
1768 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1770 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1771 See Documentation/scsi/st.txt.
1774 See header of drivers/scsi/seagate.c.
1778 Set the STI (builtin display/keyboard on the HP-PARISC
1779 machines) console (graphic card) which should be used
1780 as the initial boot-console.
1781 See also comment in drivers/video/console/sticore.c.
1784 See comment in drivers/video/console/sticore.c.
1787 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1791 Control how the NFS server code allocates CPUs to
1792 service thread pools. Depending on how many NICs
1793 you have and where their interrupts are bound, this
1794 option will affect which CPUs will do NFS serving.
1795 Note: this parameter cannot be changed while the
1796 NFS server is running.
1798 auto the server chooses an appropriate mode
1799 automatically using heuristics
1800 global a single global pool contains all CPUs
1801 percpu one pool for each CPU
1802 pernode one pool for each NUMA node (equivalent
1803 to global on non-NUMA machines)
1805 swiotlb= [IA-64] Number of I/O TLB slabs
1809 sym53c416= [HW,SCSI]
1810 See header of drivers/scsi/sym53c416.c.
1812 sysrq_always_enabled
1814 Ignore sysrq setting - this boot parameter will
1815 neutralize any effect of /proc/sys/kernel/sysrq.
1816 Useful for debugging.
1819 See header of drivers/scsi/t128.c.
1823 thash_entries= [KNL,NET]
1824 Set number of hash buckets for TCP connection
1826 time Show timing data prefixed to each printk message line
1828 tipar.timeout= [HW,PPT]
1829 Set communications timeout in tenths of a second
1832 tipar.delay= [HW,PPT]
1833 Set inter-bit delay in microseconds (default 10).
1836 See header of drivers/scsi/seagate.c.
1839 See comment before function dc390_setup() in
1840 drivers/scsi/tmscsim.c.
1844 trix= [HW,OSS] MediaTrix AudioTrix Pro
1846 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1848 tsdev.xres= [TS] Horizontal screen resolution.
1849 tsdev.yres= [TS] Vertical screen resolution.
1851 turbografx.map[2|3]= [HW,JOY]
1852 TurboGraFX parallel port interface
1854 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1855 See also Documentation/input/joystick-parport.txt
1857 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1858 See header of drivers/scsi/u14-34f.c.
1867 [USB] Ignore overcurrent events (default N).
1868 Some badly-designed motherboards generate lots of
1869 bogus events, for ports that aren't wired to
1870 anything. Set this parameter to avoid log spamming.
1871 Note that genuine overcurrent events won't be
1874 usbcore.autosuspend=
1875 [USB] The autosuspend time delay (in seconds) used
1876 for newly-detected USB devices (default 2). This
1877 is the time required before an idle device will be
1878 autosuspended. Devices for which the delay is set
1879 to a negative value won't be autosuspended at all.
1882 [USBHID] The interval which mice are to be polled at.
1885 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1886 vdso=1: enable VDSO (default)
1887 vdso=0: disable VDSO mapping
1889 video= [FB] Frame buffer configuration
1890 See Documentation/fb/modedb.txt.
1892 vga= [BOOT,IA-32] Select a particular video mode
1893 See Documentation/i386/boot.txt and
1894 Documentation/svga.txt.
1895 Use vga=ask for menu.
1896 This is actually a boot loader parameter; the value is
1897 passed to the kernel using a special protocol.
1899 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1900 size of <nn>. This can be used to increase the
1901 minimum size (128MB on x86). It can also be used to
1902 decrease the size and leave more room for directly
1905 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1908 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1911 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1914 waveartist= [HW,OSS]
1915 Format: <io>,<irq>,<dma>,<dma2>
1918 See header of drivers/scsi/wd33c93.c.
1921 See header of drivers/scsi/wd7000.c.
1924 See Documentation/watchdog/watchdog.txt.
1926 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1927 xd_geo= See header of drivers/block/xd.c.
1929 xirc2ps_cs= [NET,PCMCIA]
1931 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1933 norandmaps Don't use address space randomization
1934 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1936 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1937 This is useful to get more information why
1938 you got a "dwarf2 unwinder stuck"
1940 ______________________________________________________________________
1944 Add documentation for ALSA options.
1945 Add more DRM drivers.