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 PARIDE The ParIDE subsystem is enabled.
68 PARISC The PA-RISC architecture is enabled.
69 PCI PCI bus support is enabled.
70 PCMCIA The PCMCIA subsystem is enabled.
71 PNP Plug & Play support is enabled.
72 PPC PowerPC architecture is enabled.
73 PPT Parallel port support is enabled.
74 PS2 Appropriate PS/2 support is enabled.
75 RAM RAM disk support is enabled.
76 S390 S390 architecture is enabled.
77 SCSI Appropriate SCSI support is enabled.
78 A lot of drivers has their options described inside of
80 SELINUX SELinux support is enabled.
81 SERIAL Serial support is enabled.
82 SH SuperH architecture is enabled.
83 SMP The kernel is an SMP kernel.
84 SPARC Sparc architecture is enabled.
85 SWSUSP Software suspend is enabled.
86 TS Appropriate touchscreen support is enabled.
87 USB USB support is enabled.
88 USBHID USB Human Interface Device support is enabled.
89 V4L Video For Linux support is enabled.
90 VGA The VGA console has been enabled.
91 VT Virtual terminal support is enabled.
92 WDT Watchdog support is enabled.
93 XT IBM PC/XT MFM hard disk support is enabled.
94 X86-64 X86-64 architecture is enabled.
95 More X86-64 boot options can be found in
96 Documentation/x86_64/boot-options.txt .
98 In addition, the following text indicates that the option:
100 BUGS= Relates to possible processor bugs on the said processor.
101 KNL Is a kernel start-up parameter.
102 BOOT Is a boot loader parameter.
104 Parameters denoted with BOOT are actually interpreted by the boot
105 loader, and have no meaning to the kernel directly.
106 Do not modify the syntax of boot loader parameters without extreme
107 need or coordination with <Documentation/i386/boot.txt>.
109 There are also arch-specific kernel-parameters not documented here.
110 See for example <Documentation/x86_64/boot-options.txt>.
112 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
113 a trailing = on the name of any parameter states that that parameter will
114 be entered as an environment variable, whereas its absence indicates that
115 it will appear as a kernel argument readable via /proc/cmdline by programs
116 running once the system is up.
118 The number of kernel parameters is not limited, but the length of the
119 complete command line (parameters including spaces etc.) is limited to
120 a fixed number of characters. This limit depends on the architecture
121 and is between 256 and 4096 characters. It is defined in the file
122 ./include/asm/setup.h as COMMAND_LINE_SIZE.
125 53c7xx= [HW,SCSI] Amiga SCSI controllers
126 See header of drivers/scsi/53c7xx.c.
127 See also Documentation/scsi/ncr53c7xx.txt.
129 acpi= [HW,ACPI,X86-64,i386]
130 Advanced Configuration and Power Interface
131 Format: { force | off | ht | strict | noirq }
132 force -- enable ACPI if default was off
133 off -- disable ACPI if default was on
134 noirq -- do not use ACPI for IRQ routing
135 ht -- run only enough ACPI to enable Hyper Threading
136 strict -- Be less tolerant of platforms that are not
137 strictly ACPI specification compliant.
139 See also Documentation/pm.txt, pci=noacpi
141 acpi_apic_instance= [ACPI, IOAPIC]
143 2: use 2nd APIC table, if available
144 1,0: use 1st APIC table
147 acpi_sleep= [HW,ACPI] Sleep options
148 Format: { s3_bios, s3_mode }
149 See Documentation/power/video.txt
151 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
152 Format: { level | edge | high | low }
154 acpi_irq_balance [HW,ACPI]
155 ACPI will balance active IRQs
158 acpi_irq_nobalance [HW,ACPI]
159 ACPI will not move active IRQs (default)
162 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
164 Format: <irq>,<irq>...
166 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
167 Format: <irq>,<irq>...
169 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
170 Format: To spoof as Windows 98: ="Microsoft Windows"
172 acpi_osi= [HW,ACPI] empty param disables _OSI
174 acpi_serialize [HW,ACPI] force serialization of AML methods
176 acpi_skip_timer_override [HW,ACPI]
177 Recognize and ignore IRQ0/pin2 Interrupt Override.
178 For broken nForce2 BIOS resulting in XT-PIC timer.
179 acpi_use_timer_override [HW,ACPI}
180 Use timer override. For some broken Nvidia NF5 boards
181 that require a timer override, but don't have
184 acpi.debug_layer= [HW,ACPI]
186 Each bit of the <int> indicates an ACPI debug layer,
187 1: enable, 0: disable. It is useful for boot time
188 debugging. After system has booted up, it can be set
189 via /sys/module/acpi/parameters/debug_layer.
190 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
191 Available bits (add the numbers together) to enable debug output
192 for specific parts of the ACPI subsystem:
193 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
194 0x10 namespace 0x20 parser 0x40 dispatcher
195 0x80 executer 0x100 resources 0x200 acpica debugger
196 0x400 os services 0x800 acpica disassembler.
197 The number can be in decimal or prefixed with 0x in hex.
198 Warning: Many of these options can produce a lot of
199 output and make your system unusable. Be very careful.
201 acpi.debug_level= [HW,ACPI]
203 Each bit of the <int> indicates an ACPI debug level,
204 1: enable, 0: disable. It is useful for boot time
205 debugging. After system has booted up, it can be set
206 via /sys/module/acpi/parameters/debug_level.
207 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
208 Available bits (add the numbers together) to enable different
209 debug output levels of the ACPI subsystem:
210 0x01 error 0x02 warn 0x04 init 0x08 debug object
211 0x10 info 0x20 init names 0x40 parse 0x80 load
212 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
213 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
214 0x10000 resources 0x20000 user requests 0x40000 package.
215 The number can be in decimal or prefixed with 0x in hex.
216 Warning: Many of these options can produce a lot of
217 output and make your system unusable. Be very careful.
220 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
222 acpi_generic_hotkey [HW,ACPI]
223 Allow consolidated generic hotkey driver to
224 override platform specific driver.
225 See also Documentation/acpi-hotkey.txt.
227 acpi_pm_good [IA-32,X86-64]
228 Override the pmtimer bug detection: force the kernel
229 to assume that this machine's pmtimer latches its value
230 and always returns good values.
232 enable_timer_pin_1 [i386,x86-64]
233 Enable PIN 1 of APIC timer
234 Can be useful to work around chipset bugs
235 (in particular on some ATI chipsets).
236 The kernel tries to set a reasonable default.
238 disable_timer_pin_1 [i386,x86-64]
239 Disable PIN 1 of APIC timer
240 Can be useful to work around chipset bugs.
243 Format: <io>,<irq>,<dma>,<dma2>
244 See also Documentation/sound/oss/AD1816.
247 Format: <io>,<irq>,<dma>,<dma2>,<type>
253 See header of drivers/scsi/advansys.c.
255 advwdt= [HW,WDT] Advantech WDT
256 Format: <iostart>,<iostop>
258 aedsp16= [HW,OSS] Audio Excel DSP 16
259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
260 See also header of sound/oss/aedsp16.c.
263 See Documentation/scsi/aha152x.txt.
266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
269 See Documentation/scsi/aic7xxx.txt.
272 See Documentation/scsi/aic79xx.txt.
274 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT
277 See also Documentation/kernel/input/joystick.txt
279 analog.map= [HW,JOY] Analog joystick and gamepad support
280 Specifies type or capabilities of an analog joystick
281 connected to one of 16 gameports
282 Format: <type1>,<type2>,..<type16>
285 Power management functions (SPARCstation-4/5 + deriv.)
287 Disable APC CPU standby support. SPARCstation-Fox does
288 not play well with APC CPU idle - disable it if you have
289 APC and your system crashes randomly.
291 apic= [APIC,i386] Change the output verbosity whilst booting
292 Format: { quiet (default) | verbose | debug }
293 Change the amount of debugging information output
294 when initialising the APIC and IO-APIC components.
296 apm= [APM] Advanced Power Management
297 See header of arch/i386/kernel/apm.c.
302 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
303 Format: <io>,<irq>,<nodeID>
307 atarimouse= [HW,MOUSE] Atari Mouse
309 atascsi= [HW,SCSI] Atari SCSI
311 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
312 EzKey and similar keyboards
314 atkbd.reset= [HW] Reset keyboard during initialization
316 atkbd.set= [HW] Select keyboard code set
317 Format: <int> (2 = AT (default), 3 = PS/2)
319 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
322 atkbd.softraw= [HW] Choose between synthetic and real raw mode
323 Format: <bool> (0 = real, 1 = synthetic (default))
325 atkbd.softrepeat= [HW]
326 Use software keyboard repeat
330 aztcd= [HW,CD] Aztech CD268 CDROM driver
331 Format: <io>,0x79 (?)
333 baycom_epp= [HW,AX25]
336 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
338 See header of drivers/net/hamradio/baycom_par.c.
340 baycom_ser_fdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
342 Format: <io>,<irq>,<mode>[,<baud>]
343 See header of drivers/net/hamradio/baycom_ser_fdx.c.
345 baycom_ser_hdx= [HW,AX25]
346 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
347 Format: <io>,<irq>,<mode>
348 See header of drivers/net/hamradio/baycom_ser_hdx.c.
350 blkmtd_device= [HW,MTD]
356 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
357 bttv.radio= Most important insmod options are available as
359 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
360 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
363 See drivers/scsi/BusLogic.c, comment before function
364 BusLogic_ParseDriverOptions().
366 c101= [NET] Moxa C101 synchronous serial card
368 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
369 Sometimes CPU hardware bugs make them report the cache
370 size incorrectly. The kernel will attempt work arounds
371 to fix known problems, but for some CPUs it is not
372 possible to determine what the correct size should be.
373 This option provides an override for these situations.
376 Format: <io>,<irq>[,PAS]
377 See header of drivers/cdrom/cdu31a.c.
379 chandev= [HW,NET] Generic channel device initialisation
381 checkreqprot [SELINUX] Set initial checkreqprot flag value.
382 Format: { "0" | "1" }
383 See security/selinux/Kconfig help text.
384 0 -- check protection applied by kernel (includes
385 any implied execute protection).
386 1 -- check protection requested by application.
387 Default value is set via a kernel config option.
388 Value can be changed at runtime via
389 /selinux/checkreqprot.
391 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
393 Forces specified clocksource (if available) to be used
394 when calculating gettimeofday(). If specified
395 clocksource is not available, it defaults to PIT.
396 Format: { pit | tsc | cyclone | pmtmr }
398 code_bytes [IA32] How many bytes of object code to print in an
405 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
406 over the 8254 in addition to over the IO-APIC. The
407 kernel tries to set a sensible default.
409 hpet= [IA-32,HPET] option to disable HPET and use PIT.
413 Format: { auto | [<io>,][<irq>] }
415 com20020= [HW,NET] ARCnet - COM20020 chipset
417 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
419 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
423 ARCnet - COM90xx chipset (memory-mapped buffers)
424 Format: <io>[,<irq>[,<memstart>]]
426 condev= [HW,S390] console device
429 console= [KNL] Output console device and options.
431 tty<n> Use the virtual console device <n>.
435 Use the specified serial port. The options are of
436 the form "bbbbpnf", where "bbbb" is the baud rate,
437 "p" is parity ("n", "o", or "e"), "n" is number of
438 bits, and "f" is flow control ("r" for RTS or
439 omit it). Default is "9600n8".
441 See Documentation/serial-console.txt for more
443 Documentation/networking/netconsole.txt for an
446 uart,io,<addr>[,options]
447 uart,mmio,<addr>[,options]
448 Start an early, polled-mode console on the 8250/16550
449 UART at the specified I/O port or MMIO address,
450 switching to the matching ttyS device later. The
451 options are the same as for ttyS, above.
453 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
455 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
458 Format: { parport<nr> | auto | none }
460 crashkernel=nn[KMG]@ss[KMG]
461 [KNL] Reserve a chunk of physical memory to
462 hold a kernel to switch to with kexec on panic.
465 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
470 cs89x0_media= [HW,NET]
471 Format: { rj45 | aui | bnc }
473 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
476 See header of drivers/s390/block/dasd_devmap.c.
478 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
479 (one device per port)
480 Format: <port#>,<type>
481 See also Documentation/input/joystick-parport.txt
483 debug [KNL] Enable kernel debugging (events log level).
486 [KNL] verbose self-tests
488 Print debugging info while doing the locking API
490 We default to 0 (no extra messages), setting it to
491 1 will print _a lot_ more information - normally
492 only useful to kernel developers.
495 Format: <area>[,<node>]
496 See also Documentation/networking/decnet.txt.
499 Set number of hash buckets for dentry cache.
502 IO parameters + enable/disable command.
504 digiepca= [HW,SERIAL]
505 See drivers/char/README.epca and
506 Documentation/digiepca.txt.
508 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
510 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
512 dmasound= [HW,OSS] Sound subsystem buffers
518 earlyprintk= [IA-32,X86-64,SH]
520 earlyprintk=serial[,ttySn[,baudrate]]
522 Append ",keep" to not disable it when the real console
525 Only vga or serial at a time, not both.
527 Currently only ttyS0 and ttyS1 are supported.
529 Interaction with the standard serial driver is not
532 The VGA output is eventually overwritten by the real
537 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
540 non-0: interrupt mode (default)
547 Format: {"of[f]" | "sk[ipmbr]"}
548 See comment in arch/i386/boot/edd.S
551 Format: <id>,<membase>,<irq>
553 eisa_irq_edge= [PARISC,HW]
554 See header of drivers/parisc/eisa.c.
557 See comment before function elanfreq_setup() in
558 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
561 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
562 See Documentation/block/as-iosched.txt and
563 Documentation/block/deadline-iosched.txt for details.
565 elfcorehdr= [IA-32, X86_64]
566 Specifies physical address of start of kernel core
567 image elf header. Generally kexec loader will
568 pass this option to capture kernel.
569 See Documentation/kdump/kdump.txt for details.
571 enforcing [SELINUX] Set initial enforcing status.
573 See security/selinux/Kconfig help text.
574 0 -- permissive (log only, no denials).
575 1 -- enforcing (deny and log).
577 Value can be changed at runtime via /selinux/enforce.
580 Format: <spdif>,[<nomix>,[<amplifier>]]
581 See also header of sound/oss/es1371.c.
583 ether= [HW,NET] Ethernet cards parameters
584 This option is obsoleted by the "netdev=" option, which
585 has equivalent usage. See its documentation for details.
587 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
592 fail_make_request=[KNL]
593 General fault injection mechanism.
594 Format: <interval>,<probability>,<space>,<times>
595 See also /Documentation/fault-injection/.
598 See header of drivers/scsi/fd_mcs.c.
601 See header of drivers/scsi/fdomain.c.
604 See Documentation/floppy.txt.
607 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
608 support via parallel port (up to 5 devices per port)
609 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
610 See also Documentation/input/joystick-parport.txt
615 See header of drivers/scsi/gdth.c.
617 gpt [EFI] Forces disk with valid GPT signature but
618 invalid Protective MBR to be treated as GPT.
625 hashdist= [KNL,NUMA] Large hashes allocated during boot
626 are distributed across NUMA nodes. Defaults on
627 for IA-64, off otherwise.
628 Format: 0 | 1 (for off | on)
630 hcl= [IA-64] SGI's Hardware Graph compatibility layer
632 hd= [EIDE] (E)IDE hard drive subsystem geometry
633 Format: <cyl>,<head>,<sect>
635 hd?= [HW] (E)IDE subsystem
636 hd?lun= See Documentation/ide.txt.
638 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
639 size of <nn>. This works even on boxes that have no
640 highmem otherwise. This also works to reduce highmem
641 size on bigger boxes.
643 highres= [KNL] Enable/disable high resolution timer mode.
644 Valid parameters: "on", "off"
648 See Documentation/isdn/README.HiSax.
650 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
652 i8042.direct [HW] Put keyboard port into non-translated mode
653 i8042.dumbkbd [HW] Pretend that controller can only read data from
654 keyboard and cannot control its state
655 (Don't attempt to blink the leds)
656 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
657 i8042.nokbd [HW] Don't check/create keyboard port
658 i8042.nomux [HW] Don't check presence of an active multiplexing
660 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
663 [HW] Frequency with which keyboard LEDs should blink
664 when kernel panics (default is 0.5 sec)
665 i8042.reset [HW] Reset the controller during init and cleanup
666 i8042.unlock [HW] Unlock (ignore) the keylock
670 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
671 indicates that the driver is running on unsupported
673 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
674 does not match list of supported models.
676 [HW] Report power status in /proc/i8k
677 (disabled by default)
678 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
681 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
682 See Documentation/mca.txt.
685 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
687 ide= [HW] (E)IDE subsystem
688 Format: ide=nodma or ide=doubler or ide=reverse
689 See Documentation/ide.txt.
691 ide?= [HW] (E)IDE subsystem
692 Format: ide?=noprobe or chipset specific parameters.
693 See Documentation/ide.txt.
695 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
696 See Documentation/ide.txt.
699 Format: idle=poll or idle=mwait
700 Poll forces a polling idle loop that can slightly improves the performance
701 of waking up a idle CPU, but will use a lot of power and make the system
702 run hot. Not recommended.
703 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
704 to not use it because it doesn't save as much power as a normal idle
705 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
708 ignore_loglevel [KNL]
709 Ignore loglevel setting - this will print /all/
710 kernel messages to the console. Useful for debugging.
713 Set number of hash buckets for inode cache.
716 See header of drivers/scsi/in2000.c.
720 Run specified binary instead of /sbin/init as init
723 initcall_debug [KNL] Trace initcalls as they are executed. Useful
724 for working out where the kernel is dying during
727 initrd= [BOOT] Specify the location of the initial ramdisk
729 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
732 combined_mode= [HW] control which driver uses IDE ports in combined
733 mode: legacy IDE driver, libata, or both
734 (in the libata case, libata.atapi_enabled=1 may be
735 useful as well). Note that using the ide or libata
736 options may affect your device naming (e.g. by
737 changing hdc to sdb).
738 Format: combined (default), ide, or libata
742 io7= [HW] IO7 for Marvel based alpha systems
743 See comment before marvel_specify_io7 in
744 arch/alpha/kernel/core_marvel.c.
747 See Documentation/nfsroot.txt.
749 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
750 See comment before ip2_setup() in drivers/char/ip2.c.
752 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
753 See header of drivers/scsi/ips.c.
755 ports= [IP_VS_FTP] IPVS ftp helper module
757 Up to 8 (IP_VS_APP_MAX_PORTS) ports
759 Format: <port>,<port>....
762 When an interrupt is not handled search all handlers
763 for it. Intended to get systems with badly broken
767 When an interrupt is not handled search all handlers
768 for it. Also check all handlers each timer
769 interrupt. Intended to get systems with badly broken
773 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
775 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
777 <cpu number>,...,<cpu number>
779 <cpu number>-<cpu number> (must be a positive range in ascending order)
781 <cpu number>,...,<cpu number>-<cpu number>
782 This option can be used to specify one or more CPUs
783 to isolate from the general SMP balancing and scheduling
784 algorithms. The only way to move a process onto or off
785 an "isolated" CPU is via the CPU affinity syscalls.
786 <cpu number> begins at 0 and the maximum value is
787 "number of CPUs in system - 1".
789 This option is the preferred way to isolate CPUs. The
790 alternative -- manually setting the CPU mask of all
791 tasks in the system -- can cause problems and
792 suboptimal load balancer performance.
795 Format: <io>,<irq>,<dma>,<setup>
799 js= [HW,JOY] Analog joystick
800 See Documentation/input/joystick.txt.
804 kstack=N [IA-32,X86-64] Print N words from the kernel stack
809 lapic [IA-32,APIC] Enable the local APIC even if BIOS
812 lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
815 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
816 Format: addr:<io>,irq:<irq>
818 llsc*= [IA64] See function print_params() in
819 arch/ia64/sn/kernel/llsc4.c.
821 load_ramdisk= [RAM] List of ramdisks to load from floppy
822 See Documentation/ramdisk.txt.
824 lockd.nlm_grace_period=P [NFS] Assign grace period.
827 lockd.nlm_tcpport=N [NFS] Assign TCP port.
830 lockd.nlm_timeout=T [NFS] Assign timeout value.
833 lockd.nlm_udpport=M [NFS] Assign UDP port.
836 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
839 loglevel= All Kernel Messages with a loglevel smaller than the
840 console loglevel will be printed to the console. It can
841 also be changed with klogd or other programs. The
842 loglevels are defined as follows:
844 0 (KERN_EMERG) system is unusable
845 1 (KERN_ALERT) action must be taken immediately
846 2 (KERN_CRIT) critical conditions
847 3 (KERN_ERR) error conditions
848 4 (KERN_WARNING) warning conditions
849 5 (KERN_NOTICE) normal but significant condition
850 6 (KERN_INFO) informational
851 7 (KERN_DEBUG) debug-level messages
853 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
854 Format: { n | nk | nM }
855 n must be a power of two. The default size
856 is set in the kernel config file.
858 lp=0 [LP] Specify parallel ports to use, e.g,
859 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
860 lp=reset first parallel port). 'lp=0' disables the
861 lp=auto printer driver. 'lp=reset' (which can be
862 specified in addition to the ports) causes
863 attached printers to be reset. Using
864 lp=port1,port2,... specifies the parallel ports
865 to associate lp devices with, starting with
866 lp0. A port specification may be 'none' to skip
867 that lp device, or a parport name such as
868 'parport0'. Specifying 'lp=auto' instead of a
869 port specification list means that device IDs
870 from each port should be examined, to see if
871 an IEEE 1284-compliant printer is attached; if
872 so, the driver will manage that printer.
873 See also header of drivers/char/lp.c.
876 Sets loops_per_jiffy to given constant, thus avoiding
877 time-consuming boot-time autodetection (up to 250 ms per
878 CPU). 0 enables autodetection (default). To determine
879 the correct value for your kernel, boot with normal
880 autodetection and see what value is printed. Note that
881 on SMP systems the preset will be applied to all CPUs,
882 which is likely to cause problems if your CPUs need
883 significantly divergent settings. An incorrect value
884 will cause delays in the kernel to be wrong, leading to
885 unpredictable I/O errors and other breakage. Although
886 unlikely, in the extreme case this might damage your
890 Format: <io>,<irq>,<dma>
892 mac5380= [HW,SCSI] Format:
893 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
895 mac53c9x= [HW,SCSI] Format:
896 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
898 machvec= [IA64] Force the use of a particular machine-vector
899 (machvec) in a generic kernel.
900 Example: machvec=hpzx1_swiotlb
902 max_loop= [LOOP] Maximum number of loopback devices that can
906 maxcpus= [SMP] Maximum number of processors that an SMP kernel
908 Using "nosmp" or "maxcpus=0" will disable SMP
909 entirely (the MPS table probe still happens, though).
910 A command-line option of "maxcpus=<NUM>", where <NUM>
911 is an integer greater than 0, limits the maximum number
912 of CPUs activated in SMP mode to <NUM>.
913 Using "maxcpus=1" on an SMP kernel is the trivial
914 case of an SMP kernel with only one CPU.
916 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
917 equal to this physical address is ignored.
919 max_luns= [SCSI] Maximum number of LUNs to probe.
920 Should be between 1 and 2^32-1.
923 [SCSI] Maximum number of LUNs received.
924 Should be between 1 and 16384.
926 mca-pentium [BUGS=IA-32]
931 Format: <port>,<irq>,<mitsumi_bug_93_wait>
935 mce [IA-32] Machine Check Exception
937 md= [HW] RAID subsystems devices and level
938 See Documentation/md.txt.
941 Format: <first>,<last>
942 Specifies range of consoles to be captured by the MDA.
944 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
945 Amount of memory to be used when the kernel is not able
946 to see the whole system memory or for test.
947 [IA-32] Use together with memmap= to avoid physical
948 address space collisions. Without memmap= PCI devices
949 could be placed at addresses belonging to unused RAM.
951 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
954 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
955 E820 memory map, as specified by the user.
956 Such memmap=exactmap lines can be constructed based on
957 BIOS output or other requirements. See the memmap=nn@ss
960 memmap=nn[KMG]@ss[KMG]
961 [KNL] Force usage of a specific region of memory
962 Region of memory to be used, from ss to ss+nn.
964 memmap=nn[KMG]#ss[KMG]
965 [KNL,ACPI] Mark specific memory as ACPI data.
966 Region of memory to be used, from ss to ss+nn.
968 memmap=nn[KMG]$ss[KMG]
969 [KNL,ACPI] Mark specific memory as reserved.
970 Region of memory to be used, from ss to ss+nn.
972 meye.*= [HW] Set MotionEye Camera parameters
973 See Documentation/video4linux/meye.txt.
978 [KNL,SMP] debug: override scheduler migration costs
979 Format: <level-1-usecs>,<level-2-usecs>,...
980 This debugging option can be used to override the
981 default scheduler migration cost matrix. The numbers
982 are indexed by 'CPU domain distance'.
983 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
984 box will set up an intra-core migration cost of
985 1 msec, an inter-core migration cost of 2 msecs,
986 and an inter-node migration cost of 3 msecs.
988 WARNING: using the wrong values here can break
989 scheduler performance, so it's only for scheduler
990 development purposes, not production environments.
993 [KNL,SMP] migration cost auto-detect verbosity
995 If a system's migration matrix reported at bootup
996 seems erroneous then this option can be used to
997 increase verbosity of the detection process.
998 We default to 0 (no extra messages), 1 will print
999 some more information, and 2 will be really
1000 verbose (probably only useful if you also have a
1001 serial console attached to the system).
1004 [KNL,SMP] multiply/divide migration costs by a factor
1006 This debug option can be used to proportionally
1007 increase or decrease the auto-detected migration
1008 costs for all entries of the migration matrix.
1009 E.g. migration_factor=150 will increase migration
1010 costs by 50%. (and thus the scheduler will be less
1011 eager migrating cache-hot tasks)
1012 migration_factor=80 will decrease migration costs
1013 by 20%. (thus the scheduler will be more eager to
1016 WARNING: using the wrong values here can break
1017 scheduler performance, so it's only for scheduler
1018 development purposes, not production environments.
1021 [MOUSE] Maximum time between finger touching and
1022 leaving touchpad surface for touch to be considered
1023 a tap and be reported as a left button click (for
1024 touchpads working in absolute mode only).
1026 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1027 reporting absolute coordinates, such as tablets
1028 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1029 reporting absolute coordinates, such as tablets
1034 MTD_Partition= [MTD]
1035 Format: <name>,<region-number>,<size>,<offset>
1037 MTD_Region= [MTD] Format:
1038 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1041 See drivers/mtd/cmdline.c.
1043 mtouchusb.raw_coordinates=
1044 [HW] Make the MicroTouch USB driver use raw coordinates
1045 ('y', default) or cooked coordinates ('n')
1047 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1050 See header of drivers/scsi/NCR_D700.c.
1054 ncr53c400= [HW,SCSI]
1056 ncr53c400a= [HW,SCSI]
1058 ncr53c406a= [HW,SCSI]
1060 ncr53c8xx= [HW,SCSI]
1062 netdev= [NET] Network devices parameters
1063 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1064 Note that mem_start is often overloaded to mean
1065 something different and driver-specific.
1066 This usage is only documented in each driver source
1070 See Documentation/nfsroot.txt.
1072 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1073 See Documentation/nfsroot.txt.
1075 nfs.callback_tcpport=
1076 [NFS] set the TCP port on which the NFSv4 callback
1077 channel should listen.
1079 nfs.idmap_cache_timeout=
1080 [NFS] set the maximum lifetime for idmapper cache
1083 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1085 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1086 emulation library even if a 387 maths coprocessor
1089 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1093 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1094 the slab allocator. Saves per-node memory, but will
1095 impact performance on real NUMA hardware.
1099 noapic [SMP,APIC] Tells the kernel to not make use of any
1100 IOAPICs that may be present in the system.
1102 noasync [HW,M68K] Disables async and sync negotiation for
1105 nobats [PPC] Do not use BATs for mapping kernel lowmem
1106 on "Classic" PPC cores.
1110 nodelayacct [KNL] Disable per-task delay accounting
1112 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1116 noexec [IA-32,X86-64]
1117 noexec=on: enable non-executable mappings (default)
1118 noexec=off: disable nn-executable mappings
1120 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1121 register save and restore. The kernel will only save
1122 legacy floating-point registers on task switch.
1126 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1127 instruction doesn't work correctly and not to
1130 nohalt [IA-64] Tells the kernel not to use the power saving
1131 function PAL_HALT_LIGHT when idle. This increases
1132 power-consumption. On the positive side, it reduces
1133 interrupt wake-up latency, which may improve performance
1134 in certain environments such as networked servers or
1137 nohz= [KNL] Boottime enable/disable dynamic ticks
1138 Valid arguments: on, off
1141 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1143 noirqdebug [IA-32] Disables the code which attempts to detect and
1144 disable unhandled interrupt sources.
1146 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1147 broken timer IRQ sources.
1149 noisapnp [ISAPNP] Disables ISA PnP code.
1151 noinitrd [RAM] Tells the kernel not to load any configured
1156 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1158 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1160 noltlbs [PPC] Do not use large page/tlb entries for kernel
1161 lowmem mapping on PPC40x.
1163 nomca [IA-64] Disable machine check abort handling
1165 nomce [IA-32] Machine Check Exception
1167 noreplace-smp [IA-32,SMP] Don't replace SMP instructions
1168 with UP alternatives
1170 noresidual [PPC] Don't use residual data on PReP machines.
1172 noresume [SWSUSP] Disables resume and restores original swap
1175 no-scroll [VGA] Disables scrollback.
1176 This is required for the Braillex ib80-piezo Braille
1177 reader made by F.H. Papenmeier (Germany).
1181 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1183 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1185 nosync [HW,M68K] Disables sync negotiation for all devices.
1187 notsc [BUGS=IA-32] Disable Time Stamp Counter
1189 nousb [USB] Disable the USB subsystem
1193 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1198 opl3sa2= [HW,OSS] Format:
1199 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1201 oprofile.timer= [HW]
1202 Use timer interrupt instead of performance counters
1207 osst= [HW,SCSI] SCSI Tape Driver
1208 Format: <buffer_size>,<write_threshold>
1209 See also Documentation/scsi/st.txt.
1211 panic= [KNL] Kernel behaviour on panic
1214 parkbd.port= [HW] Parallel port number the keyboard adapter is
1215 connected to, default is 0.
1217 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1218 0 for XT, 1 for AT (default is AT).
1221 parport= [HW,PPT] Specify parallel ports. 0 disables.
1222 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1223 Use 'auto' to force the driver to use any
1224 IRQ/DMA settings detected (the default is to
1225 ignore detected IRQ/DMA settings because of
1226 possible conflicts). You can specify the base
1227 address, IRQ, and DMA settings; IRQ and DMA
1228 should be numbers, or 'auto' (for using detected
1229 settings on that particular port), or 'nofifo'
1230 (to avoid using a FIFO even if it is detected).
1231 Parallel ports are assigned in the order they
1232 are specified on the command line, starting
1235 parport_init_mode= [HW,PPT]
1236 Configure VIA parallel port to operate in
1237 a specific mode. This is necessary on Pegasos
1238 computer where firmware has no options for setting
1239 up parallel port mode and sets it to spp.
1240 Currently this function knows 686a and 8231 chips.
1241 Format: [spp|ps2|epp|ecp|ecpepp]
1243 pas2= [HW,OSS] Format:
1244 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1247 See header of drivers/scsi/pas16.c.
1250 Halt all CPUs after the first oops has been printed for
1251 the specified number of seconds. This is to be used if
1252 your oopses keep scrolling off the screen.
1257 See header of drivers/block/paride/pcd.c.
1258 See also Documentation/paride.txt.
1260 pci=option[,option...] [PCI] various PCI subsystem options:
1261 off [IA-32] don't probe for the PCI bus
1262 bios [IA-32] force use of PCI BIOS, don't access
1263 the hardware directly. Use this if your machine
1264 has a non-standard PCI host bridge.
1265 nobios [IA-32] disallow use of PCI BIOS, only direct
1266 hardware access methods are allowed. Use this
1267 if you experience crashes upon bootup and you
1268 suspect they are caused by the BIOS.
1269 conf1 [IA-32] Force use of PCI Configuration
1271 conf2 [IA-32] Force use of PCI Configuration
1273 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1275 nomsi [MSI] If the PCI_MSI kernel config parameter is
1276 enabled, this kernel boot option can be used to
1277 disable the use of MSI interrupts system-wide.
1278 nosort [IA-32] Don't sort PCI devices according to
1279 order given by the PCI BIOS. This sorting is
1280 done to get a device order compatible with
1282 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1283 routing table. These calls are known to be buggy
1284 on several machines and they hang the machine
1285 when used, but on other computers it's the only
1286 way to get the interrupt routing table. Try
1287 this option if the kernel is unable to allocate
1288 IRQs or discover secondary PCI buses on your
1290 rom [IA-32] Assign address space to expansion ROMs.
1291 Use with caution as certain devices share
1292 address decoders between ROMs and other
1294 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1295 assigned automatically to PCI devices. You can
1296 make the kernel exclude IRQs of your ISA cards
1298 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1299 of the PIRQ table (normally generated
1300 by the BIOS) if it is outside the
1301 F0000h-100000h range.
1302 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1303 useful if the kernel is unable to find your
1304 secondary buses and you want to tell it
1305 explicitly which ones they are.
1306 assign-busses [IA-32] Always assign all PCI bus
1307 numbers ourselves, overriding
1308 whatever the firmware may have done.
1309 usepirqmask [IA-32] Honor the possible IRQ mask stored
1310 in the BIOS $PIR table. This is needed on
1311 some systems with broken BIOSes, notably
1312 some HP Pavilion N5400 and Omnibook XE3
1313 notebooks. This will have no effect if ACPI
1314 IRQ routing is enabled.
1315 noacpi [IA-32] Do not use ACPI for IRQ routing
1316 or for PCI scanning.
1317 routeirq Do IRQ routing for all PCI devices.
1318 This is normally done in pci_enable_device(),
1319 so this option is a temporary workaround
1320 for broken drivers that don't call it.
1321 firmware [ARM] Do not re-enumerate the bus but instead
1322 just use the configuration from the
1323 bootloader. This is currently used on
1324 IXP2000 systems where the bus has to be
1325 configured a certain way for adjunct CPUs.
1326 noearly [X86] Don't do any early type 1 scanning.
1327 This might help on some broken boards which
1328 machine check when some devices' config space
1329 is read. But various workarounds are disabled
1330 and some IOMMU drivers will not work.
1331 bfsort Sort PCI devices into breadth-first order.
1332 This sorting is done to get a device
1333 order compatible with older (<= 2.4) kernels.
1334 nobfsort Don't sort PCI devices into breadth-first order.
1335 cbiosize=nn[KMG] The fixed amount of bus space which is
1336 reserved for the CardBus bridge's IO window.
1337 The default value is 256 bytes.
1338 cbmemsize=nn[KMG] The fixed amount of bus space which is
1339 reserved for the CardBus bridge's memory
1340 window. The default value is 64 megabytes.
1342 pcmv= [HW,PCMCIA] BadgePAD 4
1345 See Documentation/paride.txt.
1347 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1350 See arch/parisc/kernel/pdc_chassis.c
1353 See Documentation/paride.txt.
1356 See Documentation/paride.txt.
1358 pirq= [SMP,APIC] Manual mp-table setup
1359 See Documentation/i386/IO-APIC.txt.
1361 plip= [PPT,NET] Parallel port network link
1362 Format: { parport<nr> | timid | 0 }
1363 See also Documentation/parport.txt.
1369 { on | off | curr | res | no-curr | no-res }
1372 [ISAPNP] Exclude IRQs for the autoconfiguration
1375 [ISAPNP] Exclude DMAs for the autoconfiguration
1377 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1378 Ranges are in pairs (I/O port base and size).
1381 [ISAPNP] Exclude memory regions for the
1383 Ranges are in pairs (memory base and size).
1385 profile= [KNL] Enable kernel profiling via /proc/profile
1386 Format: [schedule,]<number>
1387 Param: "schedule" - profile schedule points.
1388 Param: <number> - step/bucket size as a power of 2 for
1389 statistical time based profiling.
1390 Param: "sleep" - profile D-state sleeping (millisecs)
1392 processor.max_cstate= [HW,ACPI]
1393 Limit processor to maximum C-state
1394 max_cstate=9 overrides any DMI blacklist limit.
1396 processor.nocst [HW,ACPI]
1397 Ignore the _CST method to determine C-states,
1398 instead using the legacy FADT method
1400 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1402 See Documentation/ramdisk.txt.
1404 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1405 probe for; one of (bare|imps|exps|lifebook|any).
1406 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1408 psmouse.resetafter= [HW,MOUSE]
1409 Try to reset the device after so many bad packets
1412 [HW,MOUSE] Set desired mouse resolution, in dpi.
1413 psmouse.smartscroll=
1414 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1415 0 = disabled, 1 = enabled (default).
1417 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1419 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1422 See Documentation/paride.txt.
1424 quiet [KNL] Disable most log messages
1429 See Documentation/md.txt.
1431 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1432 See Documentation/ramdisk.txt.
1434 ramdisk_blocksize= [RAM]
1435 See Documentation/ramdisk.txt.
1437 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1438 New name for the ramdisk parameter.
1439 See Documentation/ramdisk.txt.
1441 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1442 RCU callbacks to process in one batch.
1444 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1445 RCU callbacks over which batch limiting is disabled.
1447 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1448 RCU callbacks below which batch limiting is re-enabled.
1452 Run specified binary instead of /init from the ramdisk,
1453 used for early userspace startup. See initrd.
1455 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1456 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1457 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1459 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1463 Reserves a hole at the top of the kernel virtual
1466 reset_devices [KNL] Force drivers to reset the underlying device
1467 during initialization.
1470 Specify the partition device for software suspend
1472 resume_offset= [SWSUSP]
1473 Specify the offset from the beginning of the partition
1474 given by "resume=" at which the swap header is located,
1475 in <PAGE_SIZE> units (needed only for swap files).
1476 See Documentation/power/swsusp-and-swap-files.txt
1478 retain_initrd [RAM] Keep initrd memory after extraction
1480 rhash_entries= [KNL,NET]
1481 Set number of hash buckets for route cache
1483 riscom8= [HW,SERIAL]
1484 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1486 ro [KNL] Mount root device read-only on boot
1488 root= [KNL] Root filesystem
1490 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1491 mount the root filesystem
1493 rootflags= [KNL] Set root filesystem mount option string
1495 rootfstype= [KNL] Set root filesystem type
1497 rw [KNL] Mount root device read-write on boot
1499 S [KNL] Run init in single mode
1502 See drivers/net/irda/sa1100_ir.c.
1505 Format: <io>,<irq>,<dma>,<dma2>
1507 sbni= [NET] Granch SBNI12 leased line adapter
1509 sbpcd= [HW,CD] Soundblaster CD adapter
1511 See a comment before function sbpcd_setup() in
1512 drivers/cdrom/sbpcd.c.
1514 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1515 Format: <io>[,<timeout>[,<isapnp>]]
1517 scsi_debug_*= [SCSI]
1518 See drivers/scsi/scsi_debug.c.
1520 scsi_default_dev_flags=
1521 [SCSI] SCSI default device flags
1524 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1525 Format: <vendor>:<model>:<flags>
1526 (flags are integer value)
1528 scsi_logging= [SCSI]
1530 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1531 discovered. async scans them in kernel threads,
1532 allowing boot to proceed. none ignores them, expecting
1533 user space to do the scan.
1535 selinux [SELINUX] Disable or enable SELinux at boot time.
1536 Format: { "0" | "1" }
1537 See security/selinux/Kconfig help text.
1540 Default value is set via kernel config option.
1541 If enabled at boot time, /selinux/disable can be used
1542 later to disable prior to initial policy load.
1544 selinux_compat_net =
1545 [SELINUX] Set initial selinux_compat_net flag value.
1546 Format: { "0" | "1" }
1547 0 -- use new secmark-based packet controls
1548 1 -- use legacy packet controls
1549 Default value is 0 (preferred).
1550 Value can be changed at runtime via
1551 /selinux/compat_net.
1553 serialnumber [BUGS=IA-32]
1555 sg_def_reserved_size= [SCSI]
1558 Maximal number of shapers.
1561 See header of drivers/scsi/sim710.c.
1567 Format: <io>,<irq>,<dma>
1568 See header of drivers/cdrom/sjcd.c.
1573 Format: <io1>[,<io2>[,...,<io8>]]
1575 smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
1576 attempt to substitute SMP alternatives once at boot.
1578 snd-ad1816a= [HW,ALSA]
1580 snd-ad1848= [HW,ALSA]
1582 snd-ali5451= [HW,ALSA]
1584 snd-als100= [HW,ALSA]
1586 snd-als4000= [HW,ALSA]
1588 snd-azt2320= [HW,ALSA]
1590 snd-cmi8330= [HW,ALSA]
1592 snd-cmipci= [HW,ALSA]
1594 snd-cs4231= [HW,ALSA]
1596 snd-cs4232= [HW,ALSA]
1598 snd-cs4236= [HW,ALSA]
1600 snd-cs4281= [HW,ALSA]
1602 snd-cs46xx= [HW,ALSA]
1604 snd-dt019x= [HW,ALSA]
1606 snd-dummy= [HW,ALSA]
1608 snd-emu10k1= [HW,ALSA]
1610 snd-ens1370= [HW,ALSA]
1612 snd-ens1371= [HW,ALSA]
1614 snd-es968= [HW,ALSA]
1616 snd-es1688= [HW,ALSA]
1618 snd-es18xx= [HW,ALSA]
1620 snd-es1938= [HW,ALSA]
1622 snd-es1968= [HW,ALSA]
1624 snd-fm801= [HW,ALSA]
1626 snd-gusclassic= [HW,ALSA]
1628 snd-gusextreme= [HW,ALSA]
1630 snd-gusmax= [HW,ALSA]
1634 snd-ice1712= [HW,ALSA]
1636 snd-intel8x0= [HW,ALSA]
1638 snd-interwave= [HW,ALSA]
1643 snd-korg1212= [HW,ALSA]
1645 snd-maestro3= [HW,ALSA]
1647 snd-mpu401= [HW,ALSA]
1649 snd-mtpav= [HW,ALSA]
1651 snd-nm256= [HW,ALSA]
1653 snd-opl3sa2= [HW,ALSA]
1661 snd-opti93x= [HW,ALSA]
1665 snd-rme32= [HW,ALSA]
1667 snd-rme96= [HW,ALSA]
1669 snd-rme9652= [HW,ALSA]
1675 snd-sbawe= [HW,ALSA]
1677 snd-serial= [HW,ALSA]
1679 snd-sgalaxy= [HW,ALSA]
1681 snd-sonicvibes= [HW,ALSA]
1686 snd-sun-cs4231= [HW,ALSA]
1688 snd-trident= [HW,ALSA]
1690 snd-usb-audio= [HW,ALSA,USB]
1692 snd-via82xx= [HW,ALSA]
1694 snd-virmidi= [HW,ALSA]
1696 snd-wavefront= [HW,ALSA]
1698 snd-ymfpci= [HW,ALSA]
1701 Format: <io>[,<irq>]
1703 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1704 See Documentation/sonypi.txt
1706 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1707 See Documentation/specialix.txt.
1709 spia_io_base= [HW,MTD]
1715 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1717 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1718 See Documentation/scsi/st.txt.
1721 See header of drivers/scsi/seagate.c.
1725 Set the STI (builtin display/keyboard on the HP-PARISC
1726 machines) console (graphic card) which should be used
1727 as the initial boot-console.
1728 See also comment in drivers/video/console/sticore.c.
1731 See comment in drivers/video/console/sticore.c.
1734 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1738 Control how the NFS server code allocates CPUs to
1739 service thread pools. Depending on how many NICs
1740 you have and where their interrupts are bound, this
1741 option will affect which CPUs will do NFS serving.
1742 Note: this parameter cannot be changed while the
1743 NFS server is running.
1745 auto the server chooses an appropriate mode
1746 automatically using heuristics
1747 global a single global pool contains all CPUs
1748 percpu one pool for each CPU
1749 pernode one pool for each NUMA node (equivalent
1750 to global on non-NUMA machines)
1752 swiotlb= [IA-64] Number of I/O TLB slabs
1756 sym53c416= [HW,SCSI]
1757 See header of drivers/scsi/sym53c416.c.
1759 sysrq_always_enabled
1761 Ignore sysrq setting - this boot parameter will
1762 neutralize any effect of /proc/sys/kernel/sysrq.
1763 Useful for debugging.
1766 See header of drivers/scsi/t128.c.
1770 thash_entries= [KNL,NET]
1771 Set number of hash buckets for TCP connection
1773 time Show timing data prefixed to each printk message line
1775 clocksource= [GENERIC_TIME] Override the default clocksource
1776 Override the default clocksource and use the clocksource
1777 with the name specified.
1779 tipar.timeout= [HW,PPT]
1780 Set communications timeout in tenths of a second
1783 tipar.delay= [HW,PPT]
1784 Set inter-bit delay in microseconds (default 10).
1787 See header of drivers/scsi/seagate.c.
1790 See comment before function dc390_setup() in
1791 drivers/scsi/tmscsim.c.
1795 trix= [HW,OSS] MediaTrix AudioTrix Pro
1797 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1799 tsdev.xres= [TS] Horizontal screen resolution.
1800 tsdev.yres= [TS] Vertical screen resolution.
1802 turbografx.map[2|3]= [HW,JOY]
1803 TurboGraFX parallel port interface
1805 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1806 See also Documentation/input/joystick-parport.txt
1808 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1809 See header of drivers/scsi/u14-34f.c.
1818 [USB] Ignore overcurrent events (default N).
1819 Some badly-designed motherboards generate lots of
1820 bogus events, for ports that aren't wired to
1821 anything. Set this parameter to avoid log spamming.
1822 Note that genuine overcurrent events won't be
1825 usbcore.autosuspend=
1826 [USB] The autosuspend time delay (in seconds) used
1827 for newly-detected USB devices (default 2). This
1828 is the time required before an idle device will be
1829 autosuspended. Devices for which the delay is set
1830 to a negative value won't be autosuspended at all.
1833 [USBHID] The interval which mice are to be polled at.
1836 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1837 vdso=1: enable VDSO (default)
1838 vdso=0: disable VDSO mapping
1840 video= [FB] Frame buffer configuration
1841 See Documentation/fb/modedb.txt.
1843 vga= [BOOT,IA-32] Select a particular video mode
1844 See Documentation/i386/boot.txt and
1845 Documentation/svga.txt.
1846 Use vga=ask for menu.
1847 This is actually a boot loader parameter; the value is
1848 passed to the kernel using a special protocol.
1850 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1851 size of <nn>. This can be used to increase the
1852 minimum size (128MB on x86). It can also be used to
1853 decrease the size and leave more room for directly
1856 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1859 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1862 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1865 waveartist= [HW,OSS]
1866 Format: <io>,<irq>,<dma>,<dma2>
1869 See header of drivers/scsi/wd33c93.c.
1872 See header of drivers/scsi/wd7000.c.
1875 See Documentation/watchdog/watchdog.txt.
1877 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1878 xd_geo= See header of drivers/block/xd.c.
1880 xirc2ps_cs= [NET,PCMCIA]
1882 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1884 norandmaps Don't use address space randomization
1885 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1887 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1888 This is useful to get more information why
1889 you got a "dwarf2 unwinder stuck"
1891 ______________________________________________________________________
1895 Add documentation for ALSA options.
1896 Add more DRM drivers.