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_pm_good [IA-32,X86-64]
224 Override the pmtimer bug detection: force the kernel
225 to assume that this machine's pmtimer latches its value
226 and always returns good values.
228 enable_timer_pin_1 [i386,x86-64]
229 Enable PIN 1 of APIC timer
230 Can be useful to work around chipset bugs
231 (in particular on some ATI chipsets).
232 The kernel tries to set a reasonable default.
234 disable_timer_pin_1 [i386,x86-64]
235 Disable PIN 1 of APIC timer
236 Can be useful to work around chipset bugs.
239 Format: <io>,<irq>,<dma>,<dma2>
240 See also Documentation/sound/oss/AD1816.
243 Format: <io>,<irq>,<dma>,<dma2>,<type>
249 See header of drivers/scsi/advansys.c.
251 advwdt= [HW,WDT] Advantech WDT
252 Format: <iostart>,<iostop>
254 aedsp16= [HW,OSS] Audio Excel DSP 16
255 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
256 See also header of sound/oss/aedsp16.c.
259 See Documentation/scsi/aha152x.txt.
262 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
265 See Documentation/scsi/aic7xxx.txt.
268 See Documentation/scsi/aic79xx.txt.
270 amijoy.map= [HW,JOY] Amiga joystick support
271 Map of devices attached to JOY0DAT and JOY1DAT
273 See also Documentation/kernel/input/joystick.txt
275 analog.map= [HW,JOY] Analog joystick and gamepad support
276 Specifies type or capabilities of an analog joystick
277 connected to one of 16 gameports
278 Format: <type1>,<type2>,..<type16>
281 Power management functions (SPARCstation-4/5 + deriv.)
283 Disable APC CPU standby support. SPARCstation-Fox does
284 not play well with APC CPU idle - disable it if you have
285 APC and your system crashes randomly.
287 apic= [APIC,i386] Change the output verbosity whilst booting
288 Format: { quiet (default) | verbose | debug }
289 Change the amount of debugging information output
290 when initialising the APIC and IO-APIC components.
292 apm= [APM] Advanced Power Management
293 See header of arch/i386/kernel/apm.c.
298 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
299 Format: <io>,<irq>,<nodeID>
303 atarimouse= [HW,MOUSE] Atari Mouse
305 atascsi= [HW,SCSI] Atari SCSI
307 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
308 EzKey and similar keyboards
310 atkbd.reset= [HW] Reset keyboard during initialization
312 atkbd.set= [HW] Select keyboard code set
313 Format: <int> (2 = AT (default), 3 = PS/2)
315 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
318 atkbd.softraw= [HW] Choose between synthetic and real raw mode
319 Format: <bool> (0 = real, 1 = synthetic (default))
321 atkbd.softrepeat= [HW]
322 Use software keyboard repeat
326 aztcd= [HW,CD] Aztech CD268 CDROM driver
327 Format: <io>,0x79 (?)
329 baycom_epp= [HW,AX25]
332 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
334 See header of drivers/net/hamradio/baycom_par.c.
336 baycom_ser_fdx= [HW,AX25]
337 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
338 Format: <io>,<irq>,<mode>[,<baud>]
339 See header of drivers/net/hamradio/baycom_ser_fdx.c.
341 baycom_ser_hdx= [HW,AX25]
342 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
343 Format: <io>,<irq>,<mode>
344 See header of drivers/net/hamradio/baycom_ser_hdx.c.
346 blkmtd_device= [HW,MTD]
352 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
353 bttv.radio= Most important insmod options are available as
355 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
356 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
359 See drivers/scsi/BusLogic.c, comment before function
360 BusLogic_ParseDriverOptions().
362 c101= [NET] Moxa C101 synchronous serial card
364 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
365 Sometimes CPU hardware bugs make them report the cache
366 size incorrectly. The kernel will attempt work arounds
367 to fix known problems, but for some CPUs it is not
368 possible to determine what the correct size should be.
369 This option provides an override for these situations.
372 Format: <io>,<irq>[,PAS]
373 See header of drivers/cdrom/cdu31a.c.
375 chandev= [HW,NET] Generic channel device initialisation
377 checkreqprot [SELINUX] Set initial checkreqprot flag value.
378 Format: { "0" | "1" }
379 See security/selinux/Kconfig help text.
380 0 -- check protection applied by kernel (includes
381 any implied execute protection).
382 1 -- check protection requested by application.
383 Default value is set via a kernel config option.
384 Value can be changed at runtime via
385 /selinux/checkreqprot.
387 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
389 Forces specified clocksource (if available) to be used
390 when calculating gettimeofday(). If specified
391 clocksource is not available, it defaults to PIT.
392 Format: { pit | tsc | cyclone | pmtmr }
394 clocksource= [GENERIC_TIME] Override the default clocksource
396 Override the default clocksource and use the clocksource
397 with the name specified.
398 Some clocksource names to choose from, depending on
400 [all] jiffies (this is the base, fallback clocksource)
402 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
403 pxa_timer,timer3,32k_counter,timer0_1
405 [IA-32] pit,hpet,tsc,vmi-timer;
406 scx200_hrt on Geode; cyclone on IBM x440
414 code_bytes [IA32] How many bytes of object code to print in an
421 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
422 over the 8254 in addition to over the IO-APIC. The
423 kernel tries to set a sensible default.
425 hpet= [IA-32,HPET] option to disable HPET and use PIT.
429 Format: { auto | [<io>,][<irq>] }
431 com20020= [HW,NET] ARCnet - COM20020 chipset
433 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
435 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
439 ARCnet - COM90xx chipset (memory-mapped buffers)
440 Format: <io>[,<irq>[,<memstart>]]
442 condev= [HW,S390] console device
445 console= [KNL] Output console device and options.
447 tty<n> Use the virtual console device <n>.
451 Use the specified serial port. The options are of
452 the form "bbbbpnf", where "bbbb" is the baud rate,
453 "p" is parity ("n", "o", or "e"), "n" is number of
454 bits, and "f" is flow control ("r" for RTS or
455 omit it). Default is "9600n8".
457 See Documentation/serial-console.txt for more
459 Documentation/networking/netconsole.txt for an
462 uart,io,<addr>[,options]
463 uart,mmio,<addr>[,options]
464 Start an early, polled-mode console on the 8250/16550
465 UART at the specified I/O port or MMIO address,
466 switching to the matching ttyS device later. The
467 options are the same as for ttyS, above.
469 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
471 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
474 Format: { parport<nr> | auto | none }
476 crashkernel=nn[KMG]@ss[KMG]
477 [KNL] Reserve a chunk of physical memory to
478 hold a kernel to switch to with kexec on panic.
481 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
486 cs89x0_media= [HW,NET]
487 Format: { rj45 | aui | bnc }
489 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
492 See header of drivers/s390/block/dasd_devmap.c.
494 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
495 (one device per port)
496 Format: <port#>,<type>
497 See also Documentation/input/joystick-parport.txt
499 debug [KNL] Enable kernel debugging (events log level).
502 [KNL] verbose self-tests
504 Print debugging info while doing the locking API
506 We default to 0 (no extra messages), setting it to
507 1 will print _a lot_ more information - normally
508 only useful to kernel developers.
511 Format: <area>[,<node>]
512 See also Documentation/networking/decnet.txt.
515 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
516 Change the default blue palette of the console.
517 This is a 16-member array composed of values
521 Format: <green0>,<green1>,<green2>,...,<green15>
522 Change the default green palette of the console.
523 This is a 16-member array composed of values
527 Format: <red0>,<red1>,<red2>,...,<red15>
528 Change the default red palette of the console.
529 This is a 16-member array composed of values
534 Set system-wide default UTF-8 mode for all tty's.
535 Default is 0 and by setting to 1, it enables UTF-8
536 mode for all newly opened or allocated terminals.
539 Set number of hash buckets for dentry cache.
542 IO parameters + enable/disable command.
544 digiepca= [HW,SERIAL]
545 See drivers/char/README.epca and
546 Documentation/digiepca.txt.
548 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
550 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
552 dmasound= [HW,OSS] Sound subsystem buffers
558 earlyprintk= [IA-32,X86-64,SH]
560 earlyprintk=serial[,ttySn[,baudrate]]
562 Append ",keep" to not disable it when the real console
565 Only vga or serial at a time, not both.
567 Currently only ttyS0 and ttyS1 are supported.
569 Interaction with the standard serial driver is not
572 The VGA output is eventually overwritten by the real
577 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
580 non-0: interrupt mode (default)
587 Format: {"of[f]" | "sk[ipmbr]"}
588 See comment in arch/i386/boot/edd.S
591 Format: <id>,<membase>,<irq>
593 eisa_irq_edge= [PARISC,HW]
594 See header of drivers/parisc/eisa.c.
597 See comment before function elanfreq_setup() in
598 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
601 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
602 See Documentation/block/as-iosched.txt and
603 Documentation/block/deadline-iosched.txt for details.
605 elfcorehdr= [IA-32, X86_64]
606 Specifies physical address of start of kernel core
607 image elf header. Generally kexec loader will
608 pass this option to capture kernel.
609 See Documentation/kdump/kdump.txt for details.
611 enforcing [SELINUX] Set initial enforcing status.
613 See security/selinux/Kconfig help text.
614 0 -- permissive (log only, no denials).
615 1 -- enforcing (deny and log).
617 Value can be changed at runtime via /selinux/enforce.
620 Format: <spdif>,[<nomix>,[<amplifier>]]
621 See also header of sound/oss/es1371.c.
623 ether= [HW,NET] Ethernet cards parameters
624 This option is obsoleted by the "netdev=" option, which
625 has equivalent usage. See its documentation for details.
627 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
632 fail_make_request=[KNL]
633 General fault injection mechanism.
634 Format: <interval>,<probability>,<space>,<times>
635 See also /Documentation/fault-injection/.
638 See header of drivers/scsi/fd_mcs.c.
641 See header of drivers/scsi/fdomain.c.
644 See Documentation/floppy.txt.
647 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
648 support via parallel port (up to 5 devices per port)
649 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
650 See also Documentation/input/joystick-parport.txt
655 See header of drivers/scsi/gdth.c.
657 gpt [EFI] Forces disk with valid GPT signature but
658 invalid Protective MBR to be treated as GPT.
665 hashdist= [KNL,NUMA] Large hashes allocated during boot
666 are distributed across NUMA nodes. Defaults on
667 for IA-64, off otherwise.
668 Format: 0 | 1 (for off | on)
670 hcl= [IA-64] SGI's Hardware Graph compatibility layer
672 hd= [EIDE] (E)IDE hard drive subsystem geometry
673 Format: <cyl>,<head>,<sect>
675 hd?= [HW] (E)IDE subsystem
676 hd?lun= See Documentation/ide.txt.
678 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
679 size of <nn>. This works even on boxes that have no
680 highmem otherwise. This also works to reduce highmem
681 size on bigger boxes.
683 highres= [KNL] Enable/disable high resolution timer mode.
684 Valid parameters: "on", "off"
688 See Documentation/isdn/README.HiSax.
690 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
692 i8042.direct [HW] Put keyboard port into non-translated mode
693 i8042.dumbkbd [HW] Pretend that controller can only read data from
694 keyboard and cannot control its state
695 (Don't attempt to blink the leds)
696 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
697 i8042.nokbd [HW] Don't check/create keyboard port
698 i8042.nomux [HW] Don't check presence of an active multiplexing
700 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
703 [HW] Frequency with which keyboard LEDs should blink
704 when kernel panics (default is 0.5 sec)
705 i8042.reset [HW] Reset the controller during init and cleanup
706 i8042.unlock [HW] Unlock (ignore) the keylock
710 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
711 indicates that the driver is running on unsupported
713 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
714 does not match list of supported models.
716 [HW] Report power status in /proc/i8k
717 (disabled by default)
718 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
721 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
722 See Documentation/mca.txt.
725 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
727 ide= [HW] (E)IDE subsystem
728 Format: ide=nodma or ide=doubler or ide=reverse
729 See Documentation/ide.txt.
731 ide?= [HW] (E)IDE subsystem
732 Format: ide?=noprobe or chipset specific parameters.
733 See Documentation/ide.txt.
735 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
736 See Documentation/ide.txt.
739 Format: idle=poll or idle=mwait
740 Poll forces a polling idle loop that can slightly improves the performance
741 of waking up a idle CPU, but will use a lot of power and make the system
742 run hot. Not recommended.
743 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
744 to not use it because it doesn't save as much power as a normal idle
745 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
748 ignore_loglevel [KNL]
749 Ignore loglevel setting - this will print /all/
750 kernel messages to the console. Useful for debugging.
753 Set number of hash buckets for inode cache.
756 See header of drivers/scsi/in2000.c.
760 Run specified binary instead of /sbin/init as init
763 initcall_debug [KNL] Trace initcalls as they are executed. Useful
764 for working out where the kernel is dying during
767 initrd= [BOOT] Specify the location of the initial ramdisk
769 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
774 io7= [HW] IO7 for Marvel based alpha systems
775 See comment before marvel_specify_io7 in
776 arch/alpha/kernel/core_marvel.c.
779 See Documentation/nfsroot.txt.
781 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
782 See comment before ip2_setup() in drivers/char/ip2.c.
784 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
785 See header of drivers/scsi/ips.c.
787 ports= [IP_VS_FTP] IPVS ftp helper module
789 Up to 8 (IP_VS_APP_MAX_PORTS) ports
791 Format: <port>,<port>....
794 When an interrupt is not handled search all handlers
795 for it. Intended to get systems with badly broken
799 When an interrupt is not handled search all handlers
800 for it. Also check all handlers each timer
801 interrupt. Intended to get systems with badly broken
805 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
807 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
809 <cpu number>,...,<cpu number>
811 <cpu number>-<cpu number> (must be a positive range in ascending order)
813 <cpu number>,...,<cpu number>-<cpu number>
814 This option can be used to specify one or more CPUs
815 to isolate from the general SMP balancing and scheduling
816 algorithms. The only way to move a process onto or off
817 an "isolated" CPU is via the CPU affinity syscalls.
818 <cpu number> begins at 0 and the maximum value is
819 "number of CPUs in system - 1".
821 This option is the preferred way to isolate CPUs. The
822 alternative -- manually setting the CPU mask of all
823 tasks in the system -- can cause problems and
824 suboptimal load balancer performance.
827 Format: <io>,<irq>,<dma>,<setup>
831 js= [HW,JOY] Analog joystick
832 See Documentation/input/joystick.txt.
836 kstack=N [IA-32,X86-64] Print N words from the kernel stack
841 lapic [IA-32,APIC] Enable the local APIC even if BIOS
844 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
847 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
848 Format: addr:<io>,irq:<irq>
850 legacy_serial.force [HW,IA-32,X86-64]
851 Probe for COM ports at legacy addresses even
852 if PNPBIOS or ACPI should describe them. This
853 is for working around firmware defects.
855 llsc*= [IA64] See function print_params() in
856 arch/ia64/sn/kernel/llsc4.c.
858 load_ramdisk= [RAM] List of ramdisks to load from floppy
859 See Documentation/ramdisk.txt.
861 lockd.nlm_grace_period=P [NFS] Assign grace period.
864 lockd.nlm_tcpport=N [NFS] Assign TCP port.
867 lockd.nlm_timeout=T [NFS] Assign timeout value.
870 lockd.nlm_udpport=M [NFS] Assign UDP port.
873 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
876 loglevel= All Kernel Messages with a loglevel smaller than the
877 console loglevel will be printed to the console. It can
878 also be changed with klogd or other programs. The
879 loglevels are defined as follows:
881 0 (KERN_EMERG) system is unusable
882 1 (KERN_ALERT) action must be taken immediately
883 2 (KERN_CRIT) critical conditions
884 3 (KERN_ERR) error conditions
885 4 (KERN_WARNING) warning conditions
886 5 (KERN_NOTICE) normal but significant condition
887 6 (KERN_INFO) informational
888 7 (KERN_DEBUG) debug-level messages
890 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
891 Format: { n | nk | nM }
892 n must be a power of two. The default size
893 is set in the kernel config file.
895 lp=0 [LP] Specify parallel ports to use, e.g,
896 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
897 lp=reset first parallel port). 'lp=0' disables the
898 lp=auto printer driver. 'lp=reset' (which can be
899 specified in addition to the ports) causes
900 attached printers to be reset. Using
901 lp=port1,port2,... specifies the parallel ports
902 to associate lp devices with, starting with
903 lp0. A port specification may be 'none' to skip
904 that lp device, or a parport name such as
905 'parport0'. Specifying 'lp=auto' instead of a
906 port specification list means that device IDs
907 from each port should be examined, to see if
908 an IEEE 1284-compliant printer is attached; if
909 so, the driver will manage that printer.
910 See also header of drivers/char/lp.c.
913 Sets loops_per_jiffy to given constant, thus avoiding
914 time-consuming boot-time autodetection (up to 250 ms per
915 CPU). 0 enables autodetection (default). To determine
916 the correct value for your kernel, boot with normal
917 autodetection and see what value is printed. Note that
918 on SMP systems the preset will be applied to all CPUs,
919 which is likely to cause problems if your CPUs need
920 significantly divergent settings. An incorrect value
921 will cause delays in the kernel to be wrong, leading to
922 unpredictable I/O errors and other breakage. Although
923 unlikely, in the extreme case this might damage your
927 Format: <io>,<irq>,<dma>
929 mac5380= [HW,SCSI] Format:
930 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
932 mac53c9x= [HW,SCSI] Format:
933 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
935 machvec= [IA64] Force the use of a particular machine-vector
936 (machvec) in a generic kernel.
937 Example: machvec=hpzx1_swiotlb
939 max_loop= [LOOP] Maximum number of loopback devices that can
943 maxcpus= [SMP] Maximum number of processors that an SMP kernel
945 Using "nosmp" or "maxcpus=0" will disable SMP
946 entirely (the MPS table probe still happens, though).
947 A command-line option of "maxcpus=<NUM>", where <NUM>
948 is an integer greater than 0, limits the maximum number
949 of CPUs activated in SMP mode to <NUM>.
950 Using "maxcpus=1" on an SMP kernel is the trivial
951 case of an SMP kernel with only one CPU.
953 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
954 equal to this physical address is ignored.
956 max_luns= [SCSI] Maximum number of LUNs to probe.
957 Should be between 1 and 2^32-1.
960 [SCSI] Maximum number of LUNs received.
961 Should be between 1 and 16384.
963 mca-pentium [BUGS=IA-32]
968 Format: <port>,<irq>,<mitsumi_bug_93_wait>
972 mce [IA-32] Machine Check Exception
974 md= [HW] RAID subsystems devices and level
975 See Documentation/md.txt.
978 Format: <first>,<last>
979 Specifies range of consoles to be captured by the MDA.
981 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
982 Amount of memory to be used when the kernel is not able
983 to see the whole system memory or for test.
984 [IA-32] Use together with memmap= to avoid physical
985 address space collisions. Without memmap= PCI devices
986 could be placed at addresses belonging to unused RAM.
988 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
991 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
992 E820 memory map, as specified by the user.
993 Such memmap=exactmap lines can be constructed based on
994 BIOS output or other requirements. See the memmap=nn@ss
997 memmap=nn[KMG]@ss[KMG]
998 [KNL] Force usage of a specific region of memory
999 Region of memory to be used, from ss to ss+nn.
1001 memmap=nn[KMG]#ss[KMG]
1002 [KNL,ACPI] Mark specific memory as ACPI data.
1003 Region of memory to be used, from ss to ss+nn.
1005 memmap=nn[KMG]$ss[KMG]
1006 [KNL,ACPI] Mark specific memory as reserved.
1007 Region of memory to be used, from ss to ss+nn.
1009 meye.*= [HW] Set MotionEye Camera parameters
1010 See Documentation/video4linux/meye.txt.
1015 [KNL,SMP] debug: override scheduler migration costs
1016 Format: <level-1-usecs>,<level-2-usecs>,...
1017 This debugging option can be used to override the
1018 default scheduler migration cost matrix. The numbers
1019 are indexed by 'CPU domain distance'.
1020 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
1021 box will set up an intra-core migration cost of
1022 1 msec, an inter-core migration cost of 2 msecs,
1023 and an inter-node migration cost of 3 msecs.
1025 WARNING: using the wrong values here can break
1026 scheduler performance, so it's only for scheduler
1027 development purposes, not production environments.
1030 [KNL,SMP] migration cost auto-detect verbosity
1032 If a system's migration matrix reported at bootup
1033 seems erroneous then this option can be used to
1034 increase verbosity of the detection process.
1035 We default to 0 (no extra messages), 1 will print
1036 some more information, and 2 will be really
1037 verbose (probably only useful if you also have a
1038 serial console attached to the system).
1041 [KNL,SMP] multiply/divide migration costs by a factor
1043 This debug option can be used to proportionally
1044 increase or decrease the auto-detected migration
1045 costs for all entries of the migration matrix.
1046 E.g. migration_factor=150 will increase migration
1047 costs by 50%. (and thus the scheduler will be less
1048 eager migrating cache-hot tasks)
1049 migration_factor=80 will decrease migration costs
1050 by 20%. (thus the scheduler will be more eager to
1053 WARNING: using the wrong values here can break
1054 scheduler performance, so it's only for scheduler
1055 development purposes, not production environments.
1058 [MOUSE] Maximum time between finger touching and
1059 leaving touchpad surface for touch to be considered
1060 a tap and be reported as a left button click (for
1061 touchpads working in absolute mode only).
1063 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1064 reporting absolute coordinates, such as tablets
1065 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1066 reporting absolute coordinates, such as tablets
1071 MTD_Partition= [MTD]
1072 Format: <name>,<region-number>,<size>,<offset>
1074 MTD_Region= [MTD] Format:
1075 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1078 See drivers/mtd/cmdline.c.
1080 mtouchusb.raw_coordinates=
1081 [HW] Make the MicroTouch USB driver use raw coordinates
1082 ('y', default) or cooked coordinates ('n')
1084 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1087 See header of drivers/scsi/NCR_D700.c.
1091 ncr53c400= [HW,SCSI]
1093 ncr53c400a= [HW,SCSI]
1095 ncr53c406a= [HW,SCSI]
1097 ncr53c8xx= [HW,SCSI]
1099 netdev= [NET] Network devices parameters
1100 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1101 Note that mem_start is often overloaded to mean
1102 something different and driver-specific.
1103 This usage is only documented in each driver source
1107 See Documentation/nfsroot.txt.
1109 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1110 See Documentation/nfsroot.txt.
1112 nfs.callback_tcpport=
1113 [NFS] set the TCP port on which the NFSv4 callback
1114 channel should listen.
1116 nfs.idmap_cache_timeout=
1117 [NFS] set the maximum lifetime for idmapper cache
1120 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1122 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1123 emulation library even if a 387 maths coprocessor
1126 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1130 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1131 caches in the slab allocator. Saves per-node memory,
1132 but will impact performance.
1136 noapic [SMP,APIC] Tells the kernel to not make use of any
1137 IOAPICs that may be present in the system.
1139 noasync [HW,M68K] Disables async and sync negotiation for
1142 nobats [PPC] Do not use BATs for mapping kernel lowmem
1143 on "Classic" PPC cores.
1147 nodelayacct [KNL] Disable per-task delay accounting
1149 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1153 noexec [IA-32,X86-64]
1154 noexec=on: enable non-executable mappings (default)
1155 noexec=off: disable nn-executable mappings
1157 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1158 register save and restore. The kernel will only save
1159 legacy floating-point registers on task switch.
1163 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1164 instruction doesn't work correctly and not to
1167 nohalt [IA-64] Tells the kernel not to use the power saving
1168 function PAL_HALT_LIGHT when idle. This increases
1169 power-consumption. On the positive side, it reduces
1170 interrupt wake-up latency, which may improve performance
1171 in certain environments such as networked servers or
1174 nohz= [KNL] Boottime enable/disable dynamic ticks
1175 Valid arguments: on, off
1178 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1180 noirqdebug [IA-32] Disables the code which attempts to detect and
1181 disable unhandled interrupt sources.
1183 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1184 broken timer IRQ sources.
1186 noisapnp [ISAPNP] Disables ISA PnP code.
1188 noinitrd [RAM] Tells the kernel not to load any configured
1193 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1195 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1197 noltlbs [PPC] Do not use large page/tlb entries for kernel
1198 lowmem mapping on PPC40x.
1200 nomca [IA-64] Disable machine check abort handling
1202 nomce [IA-32] Machine Check Exception
1204 noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
1206 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1207 with UP alternatives
1209 noresidual [PPC] Don't use residual data on PReP machines.
1211 noresume [SWSUSP] Disables resume and restores original swap
1214 no-scroll [VGA] Disables scrollback.
1215 This is required for the Braillex ib80-piezo Braille
1216 reader made by F.H. Papenmeier (Germany).
1220 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1222 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1224 nosync [HW,M68K] Disables sync negotiation for all devices.
1226 notsc [BUGS=IA-32] Disable Time Stamp Counter
1228 nousb [USB] Disable the USB subsystem
1232 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1237 opl3sa2= [HW,OSS] Format:
1238 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1240 oprofile.timer= [HW]
1241 Use timer interrupt instead of performance counters
1246 osst= [HW,SCSI] SCSI Tape Driver
1247 Format: <buffer_size>,<write_threshold>
1248 See also Documentation/scsi/st.txt.
1250 panic= [KNL] Kernel behaviour on panic
1253 parkbd.port= [HW] Parallel port number the keyboard adapter is
1254 connected to, default is 0.
1256 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1257 0 for XT, 1 for AT (default is AT).
1260 parport= [HW,PPT] Specify parallel ports. 0 disables.
1261 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1262 Use 'auto' to force the driver to use any
1263 IRQ/DMA settings detected (the default is to
1264 ignore detected IRQ/DMA settings because of
1265 possible conflicts). You can specify the base
1266 address, IRQ, and DMA settings; IRQ and DMA
1267 should be numbers, or 'auto' (for using detected
1268 settings on that particular port), or 'nofifo'
1269 (to avoid using a FIFO even if it is detected).
1270 Parallel ports are assigned in the order they
1271 are specified on the command line, starting
1274 parport_init_mode= [HW,PPT]
1275 Configure VIA parallel port to operate in
1276 a specific mode. This is necessary on Pegasos
1277 computer where firmware has no options for setting
1278 up parallel port mode and sets it to spp.
1279 Currently this function knows 686a and 8231 chips.
1280 Format: [spp|ps2|epp|ecp|ecpepp]
1282 pas2= [HW,OSS] Format:
1283 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1286 See header of drivers/scsi/pas16.c.
1289 Halt all CPUs after the first oops has been printed for
1290 the specified number of seconds. This is to be used if
1291 your oopses keep scrolling off the screen.
1296 See header of drivers/block/paride/pcd.c.
1297 See also Documentation/paride.txt.
1299 pci=option[,option...] [PCI] various PCI subsystem options:
1300 off [IA-32] don't probe for the PCI bus
1301 bios [IA-32] force use of PCI BIOS, don't access
1302 the hardware directly. Use this if your machine
1303 has a non-standard PCI host bridge.
1304 nobios [IA-32] disallow use of PCI BIOS, only direct
1305 hardware access methods are allowed. Use this
1306 if you experience crashes upon bootup and you
1307 suspect they are caused by the BIOS.
1308 conf1 [IA-32] Force use of PCI Configuration
1310 conf2 [IA-32] Force use of PCI Configuration
1312 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1314 nomsi [MSI] If the PCI_MSI kernel config parameter is
1315 enabled, this kernel boot option can be used to
1316 disable the use of MSI interrupts system-wide.
1317 nosort [IA-32] Don't sort PCI devices according to
1318 order given by the PCI BIOS. This sorting is
1319 done to get a device order compatible with
1321 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1322 routing table. These calls are known to be buggy
1323 on several machines and they hang the machine
1324 when used, but on other computers it's the only
1325 way to get the interrupt routing table. Try
1326 this option if the kernel is unable to allocate
1327 IRQs or discover secondary PCI buses on your
1329 rom [IA-32] Assign address space to expansion ROMs.
1330 Use with caution as certain devices share
1331 address decoders between ROMs and other
1333 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1334 assigned automatically to PCI devices. You can
1335 make the kernel exclude IRQs of your ISA cards
1337 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1338 of the PIRQ table (normally generated
1339 by the BIOS) if it is outside the
1340 F0000h-100000h range.
1341 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1342 useful if the kernel is unable to find your
1343 secondary buses and you want to tell it
1344 explicitly which ones they are.
1345 assign-busses [IA-32] Always assign all PCI bus
1346 numbers ourselves, overriding
1347 whatever the firmware may have done.
1348 usepirqmask [IA-32] Honor the possible IRQ mask stored
1349 in the BIOS $PIR table. This is needed on
1350 some systems with broken BIOSes, notably
1351 some HP Pavilion N5400 and Omnibook XE3
1352 notebooks. This will have no effect if ACPI
1353 IRQ routing is enabled.
1354 noacpi [IA-32] Do not use ACPI for IRQ routing
1355 or for PCI scanning.
1356 routeirq Do IRQ routing for all PCI devices.
1357 This is normally done in pci_enable_device(),
1358 so this option is a temporary workaround
1359 for broken drivers that don't call it.
1360 firmware [ARM] Do not re-enumerate the bus but instead
1361 just use the configuration from the
1362 bootloader. This is currently used on
1363 IXP2000 systems where the bus has to be
1364 configured a certain way for adjunct CPUs.
1365 noearly [X86] Don't do any early type 1 scanning.
1366 This might help on some broken boards which
1367 machine check when some devices' config space
1368 is read. But various workarounds are disabled
1369 and some IOMMU drivers will not work.
1370 bfsort Sort PCI devices into breadth-first order.
1371 This sorting is done to get a device
1372 order compatible with older (<= 2.4) kernels.
1373 nobfsort Don't sort PCI devices into breadth-first order.
1374 cbiosize=nn[KMG] The fixed amount of bus space which is
1375 reserved for the CardBus bridge's IO window.
1376 The default value is 256 bytes.
1377 cbmemsize=nn[KMG] The fixed amount of bus space which is
1378 reserved for the CardBus bridge's memory
1379 window. The default value is 64 megabytes.
1381 pcmv= [HW,PCMCIA] BadgePAD 4
1384 See Documentation/paride.txt.
1386 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1389 See arch/parisc/kernel/pdc_chassis.c
1392 See Documentation/paride.txt.
1395 See Documentation/paride.txt.
1397 pirq= [SMP,APIC] Manual mp-table setup
1398 See Documentation/i386/IO-APIC.txt.
1400 plip= [PPT,NET] Parallel port network link
1401 Format: { parport<nr> | timid | 0 }
1402 See also Documentation/parport.txt.
1408 { on | off | curr | res | no-curr | no-res }
1411 [ISAPNP] Exclude IRQs for the autoconfiguration
1414 [ISAPNP] Exclude DMAs for the autoconfiguration
1416 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1417 Ranges are in pairs (I/O port base and size).
1420 [ISAPNP] Exclude memory regions for the
1422 Ranges are in pairs (memory base and size).
1424 profile= [KNL] Enable kernel profiling via /proc/profile
1425 Format: [schedule,]<number>
1426 Param: "schedule" - profile schedule points.
1427 Param: <number> - step/bucket size as a power of 2 for
1428 statistical time based profiling.
1429 Param: "sleep" - profile D-state sleeping (millisecs)
1431 processor.max_cstate= [HW,ACPI]
1432 Limit processor to maximum C-state
1433 max_cstate=9 overrides any DMI blacklist limit.
1435 processor.nocst [HW,ACPI]
1436 Ignore the _CST method to determine C-states,
1437 instead using the legacy FADT method
1439 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1441 See Documentation/ramdisk.txt.
1443 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1444 probe for; one of (bare|imps|exps|lifebook|any).
1445 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1447 psmouse.resetafter= [HW,MOUSE]
1448 Try to reset the device after so many bad packets
1451 [HW,MOUSE] Set desired mouse resolution, in dpi.
1452 psmouse.smartscroll=
1453 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1454 0 = disabled, 1 = enabled (default).
1456 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1458 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1461 See Documentation/paride.txt.
1463 quiet [KNL] Disable most log messages
1468 See Documentation/md.txt.
1470 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1471 See Documentation/ramdisk.txt.
1473 ramdisk_blocksize= [RAM]
1474 See Documentation/ramdisk.txt.
1476 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1477 New name for the ramdisk parameter.
1478 See Documentation/ramdisk.txt.
1480 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1481 RCU callbacks to process in one batch.
1483 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1484 RCU callbacks over which batch limiting is disabled.
1486 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1487 RCU callbacks below which batch limiting is re-enabled.
1491 Run specified binary instead of /init from the ramdisk,
1492 used for early userspace startup. See initrd.
1494 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1495 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1496 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1498 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1502 Reserves a hole at the top of the kernel virtual
1505 reset_devices [KNL] Force drivers to reset the underlying device
1506 during initialization.
1509 Specify the partition device for software suspend
1511 resume_offset= [SWSUSP]
1512 Specify the offset from the beginning of the partition
1513 given by "resume=" at which the swap header is located,
1514 in <PAGE_SIZE> units (needed only for swap files).
1515 See Documentation/power/swsusp-and-swap-files.txt
1517 retain_initrd [RAM] Keep initrd memory after extraction
1519 rhash_entries= [KNL,NET]
1520 Set number of hash buckets for route cache
1522 riscom8= [HW,SERIAL]
1523 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1525 ro [KNL] Mount root device read-only on boot
1527 root= [KNL] Root filesystem
1529 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1530 mount the root filesystem
1532 rootflags= [KNL] Set root filesystem mount option string
1534 rootfstype= [KNL] Set root filesystem type
1536 rw [KNL] Mount root device read-write on boot
1538 S [KNL] Run init in single mode
1541 See drivers/net/irda/sa1100_ir.c.
1544 Format: <io>,<irq>,<dma>,<dma2>
1546 sbni= [NET] Granch SBNI12 leased line adapter
1548 sbpcd= [HW,CD] Soundblaster CD adapter
1550 See a comment before function sbpcd_setup() in
1551 drivers/cdrom/sbpcd.c.
1553 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1554 Format: <io>[,<timeout>[,<isapnp>]]
1556 scsi_debug_*= [SCSI]
1557 See drivers/scsi/scsi_debug.c.
1559 scsi_default_dev_flags=
1560 [SCSI] SCSI default device flags
1563 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1564 Format: <vendor>:<model>:<flags>
1565 (flags are integer value)
1567 scsi_logging= [SCSI]
1569 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1570 discovered. async scans them in kernel threads,
1571 allowing boot to proceed. none ignores them, expecting
1572 user space to do the scan.
1574 selinux [SELINUX] Disable or enable SELinux at boot time.
1575 Format: { "0" | "1" }
1576 See security/selinux/Kconfig help text.
1579 Default value is set via kernel config option.
1580 If enabled at boot time, /selinux/disable can be used
1581 later to disable prior to initial policy load.
1583 selinux_compat_net =
1584 [SELINUX] Set initial selinux_compat_net flag value.
1585 Format: { "0" | "1" }
1586 0 -- use new secmark-based packet controls
1587 1 -- use legacy packet controls
1588 Default value is 0 (preferred).
1589 Value can be changed at runtime via
1590 /selinux/compat_net.
1592 serialnumber [BUGS=IA-32]
1594 sg_def_reserved_size= [SCSI]
1597 Maximal number of shapers.
1600 See header of drivers/scsi/sim710.c.
1606 Format: <io>,<irq>,<dma>
1607 See header of drivers/cdrom/sjcd.c.
1611 slub_debug [MM, SLUB]
1612 Enabling slub_debug allows one to determine the culprit
1613 if slab objects become corrupted. Enabling slub_debug
1614 creates guard zones around objects and poisons objects
1615 when not in use. Also tracks the last alloc / free.
1616 For more information see Documentation/vm/slub.txt.
1618 slub_max_order= [MM, SLUB]
1619 Determines the maximum allowed order for slabs. Setting
1620 this too high may cause fragmentation.
1621 For more information see Documentation/vm/slub.txt.
1623 slub_min_objects= [MM, SLUB]
1624 The minimum objects per slab. SLUB will increase the
1625 slab order up to slub_max_order to generate a
1626 sufficiently big slab to satisfy the number of objects.
1627 The higher the number of objects the smaller the overhead
1629 For more information see Documentation/vm/slub.txt.
1631 slub_min_order= [MM, SLUB]
1632 Determines the mininum page order for slabs. Must be
1633 lower than slub_max_order
1634 For more information see Documentation/vm/slub.txt.
1636 slub_nomerge [MM, SLUB]
1637 Disable merging of slabs of similar size. May be
1638 necessary if there is some reason to distinguish
1639 allocs to different slabs.
1640 For more information see Documentation/vm/slub.txt.
1643 Format: <io1>[,<io2>[,...,<io8>]]
1645 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1646 attempt to substitute SMP alternatives once at boot.
1648 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1649 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1650 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1651 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1652 smsc-ircc2.ircc_irq= [HW] IRQ line
1653 smsc-ircc2.ircc_dma= [HW] DMA channel
1654 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1655 0: Toshiba Satellite 1800 (GP data pin select)
1656 1: Fast pin select (default)
1659 snd-ad1816a= [HW,ALSA]
1661 snd-ad1848= [HW,ALSA]
1663 snd-ali5451= [HW,ALSA]
1665 snd-als100= [HW,ALSA]
1667 snd-als4000= [HW,ALSA]
1669 snd-azt2320= [HW,ALSA]
1671 snd-cmi8330= [HW,ALSA]
1673 snd-cmipci= [HW,ALSA]
1675 snd-cs4231= [HW,ALSA]
1677 snd-cs4232= [HW,ALSA]
1679 snd-cs4236= [HW,ALSA]
1681 snd-cs4281= [HW,ALSA]
1683 snd-cs46xx= [HW,ALSA]
1685 snd-dt019x= [HW,ALSA]
1687 snd-dummy= [HW,ALSA]
1689 snd-emu10k1= [HW,ALSA]
1691 snd-ens1370= [HW,ALSA]
1693 snd-ens1371= [HW,ALSA]
1695 snd-es968= [HW,ALSA]
1697 snd-es1688= [HW,ALSA]
1699 snd-es18xx= [HW,ALSA]
1701 snd-es1938= [HW,ALSA]
1703 snd-es1968= [HW,ALSA]
1705 snd-fm801= [HW,ALSA]
1707 snd-gusclassic= [HW,ALSA]
1709 snd-gusextreme= [HW,ALSA]
1711 snd-gusmax= [HW,ALSA]
1715 snd-ice1712= [HW,ALSA]
1717 snd-intel8x0= [HW,ALSA]
1719 snd-interwave= [HW,ALSA]
1724 snd-korg1212= [HW,ALSA]
1726 snd-maestro3= [HW,ALSA]
1728 snd-mpu401= [HW,ALSA]
1730 snd-mtpav= [HW,ALSA]
1732 snd-nm256= [HW,ALSA]
1734 snd-opl3sa2= [HW,ALSA]
1742 snd-opti93x= [HW,ALSA]
1746 snd-rme32= [HW,ALSA]
1748 snd-rme96= [HW,ALSA]
1750 snd-rme9652= [HW,ALSA]
1756 snd-sbawe= [HW,ALSA]
1758 snd-serial= [HW,ALSA]
1760 snd-sgalaxy= [HW,ALSA]
1762 snd-sonicvibes= [HW,ALSA]
1767 snd-sun-cs4231= [HW,ALSA]
1769 snd-trident= [HW,ALSA]
1771 snd-usb-audio= [HW,ALSA,USB]
1773 snd-via82xx= [HW,ALSA]
1775 snd-virmidi= [HW,ALSA]
1777 snd-wavefront= [HW,ALSA]
1779 snd-ymfpci= [HW,ALSA]
1782 Format: <io>[,<irq>]
1784 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1785 See Documentation/sonypi.txt
1787 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1788 See Documentation/specialix.txt.
1790 spia_io_base= [HW,MTD]
1796 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1798 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1799 See Documentation/scsi/st.txt.
1802 See header of drivers/scsi/seagate.c.
1806 Set the STI (builtin display/keyboard on the HP-PARISC
1807 machines) console (graphic card) which should be used
1808 as the initial boot-console.
1809 See also comment in drivers/video/console/sticore.c.
1812 See comment in drivers/video/console/sticore.c.
1815 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1819 Control how the NFS server code allocates CPUs to
1820 service thread pools. Depending on how many NICs
1821 you have and where their interrupts are bound, this
1822 option will affect which CPUs will do NFS serving.
1823 Note: this parameter cannot be changed while the
1824 NFS server is running.
1826 auto the server chooses an appropriate mode
1827 automatically using heuristics
1828 global a single global pool contains all CPUs
1829 percpu one pool for each CPU
1830 pernode one pool for each NUMA node (equivalent
1831 to global on non-NUMA machines)
1833 swiotlb= [IA-64] Number of I/O TLB slabs
1837 sym53c416= [HW,SCSI]
1838 See header of drivers/scsi/sym53c416.c.
1840 sysrq_always_enabled
1842 Ignore sysrq setting - this boot parameter will
1843 neutralize any effect of /proc/sys/kernel/sysrq.
1844 Useful for debugging.
1847 See header of drivers/scsi/t128.c.
1851 thash_entries= [KNL,NET]
1852 Set number of hash buckets for TCP connection
1854 time Show timing data prefixed to each printk message line
1856 tipar.timeout= [HW,PPT]
1857 Set communications timeout in tenths of a second
1860 tipar.delay= [HW,PPT]
1861 Set inter-bit delay in microseconds (default 10).
1864 See header of drivers/scsi/seagate.c.
1867 See comment before function dc390_setup() in
1868 drivers/scsi/tmscsim.c.
1872 trix= [HW,OSS] MediaTrix AudioTrix Pro
1874 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1876 tsdev.xres= [TS] Horizontal screen resolution.
1877 tsdev.yres= [TS] Vertical screen resolution.
1879 turbografx.map[2|3]= [HW,JOY]
1880 TurboGraFX parallel port interface
1882 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1883 See also Documentation/input/joystick-parport.txt
1885 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1886 See header of drivers/scsi/u14-34f.c.
1895 [USB] Ignore overcurrent events (default N).
1896 Some badly-designed motherboards generate lots of
1897 bogus events, for ports that aren't wired to
1898 anything. Set this parameter to avoid log spamming.
1899 Note that genuine overcurrent events won't be
1902 usbcore.autosuspend=
1903 [USB] The autosuspend time delay (in seconds) used
1904 for newly-detected USB devices (default 2). This
1905 is the time required before an idle device will be
1906 autosuspended. Devices for which the delay is set
1907 to a negative value won't be autosuspended at all.
1910 [USBHID] The interval which mice are to be polled at.
1913 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1914 vdso=1: enable VDSO (default)
1915 vdso=0: disable VDSO mapping
1917 video= [FB] Frame buffer configuration
1918 See Documentation/fb/modedb.txt.
1920 vga= [BOOT,IA-32] Select a particular video mode
1921 See Documentation/i386/boot.txt and
1922 Documentation/svga.txt.
1923 Use vga=ask for menu.
1924 This is actually a boot loader parameter; the value is
1925 passed to the kernel using a special protocol.
1927 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1928 size of <nn>. This can be used to increase the
1929 minimum size (128MB on x86). It can also be used to
1930 decrease the size and leave more room for directly
1933 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1936 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1939 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1942 waveartist= [HW,OSS]
1943 Format: <io>,<irq>,<dma>,<dma2>
1946 See header of drivers/scsi/wd33c93.c.
1949 See header of drivers/scsi/wd7000.c.
1952 See Documentation/watchdog/watchdog.txt.
1954 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1955 xd_geo= See header of drivers/block/xd.c.
1957 xirc2ps_cs= [NET,PCMCIA]
1959 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1961 norandmaps Don't use address space randomization
1962 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1964 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1965 This is useful to get more information why
1966 you got a "dwarf2 unwinder stuck"
1968 ______________________________________________________________________
1972 Add documentation for ALSA options.
1973 Add more DRM drivers.