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_sleep= [HW,ACPI] Sleep options
142 Format: { s3_bios, s3_mode }
143 See Documentation/power/video.txt
145 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
146 Format: { level | edge | high | low }
148 acpi_irq_balance [HW,ACPI]
149 ACPI will balance active IRQs
152 acpi_irq_nobalance [HW,ACPI]
153 ACPI will not move active IRQs (default)
156 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
158 Format: <irq>,<irq>...
160 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
161 Format: <irq>,<irq>...
163 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
164 Format: To spoof as Windows 98: ="Microsoft Windows"
166 acpi_osi= [HW,ACPI] empty param disables _OSI
168 acpi_serialize [HW,ACPI] force serialization of AML methods
170 acpi_skip_timer_override [HW,ACPI]
171 Recognize and ignore IRQ0/pin2 Interrupt Override.
172 For broken nForce2 BIOS resulting in XT-PIC timer.
173 acpi_use_timer_override [HW,ACPI}
174 Use timer override. For some broken Nvidia NF5 boards
175 that require a timer override, but don't have
178 acpi_dbg_layer= [HW,ACPI]
180 Each bit of the <int> indicates an ACPI debug layer,
181 1: enable, 0: disable. It is useful for boot time
182 debugging. After system has booted up, it can be set
183 via /proc/acpi/debug_layer.
185 acpi_dbg_level= [HW,ACPI]
187 Each bit of the <int> indicates an ACPI debug level,
188 1: enable, 0: disable. It is useful for boot time
189 debugging. After system has booted up, it can be set
190 via /proc/acpi/debug_level.
192 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
194 acpi_generic_hotkey [HW,ACPI]
195 Allow consolidated generic hotkey driver to
196 override platform specific driver.
197 See also Documentation/acpi-hotkey.txt.
199 acpi_pm_good [IA-32,X86-64]
200 Override the pmtimer bug detection: force the kernel
201 to assume that this machine's pmtimer latches its value
202 and always returns good values.
204 enable_timer_pin_1 [i386,x86-64]
205 Enable PIN 1 of APIC timer
206 Can be useful to work around chipset bugs
207 (in particular on some ATI chipsets).
208 The kernel tries to set a reasonable default.
210 disable_timer_pin_1 [i386,x86-64]
211 Disable PIN 1 of APIC timer
212 Can be useful to work around chipset bugs.
215 Format: <io>,<irq>,<dma>,<dma2>
216 See also Documentation/sound/oss/AD1816.
219 Format: <io>,<irq>,<dma>,<dma2>,<type>
225 See header of drivers/scsi/advansys.c.
227 advwdt= [HW,WDT] Advantech WDT
228 Format: <iostart>,<iostop>
230 aedsp16= [HW,OSS] Audio Excel DSP 16
231 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
232 See also header of sound/oss/aedsp16.c.
235 See Documentation/scsi/aha152x.txt.
238 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
241 See Documentation/scsi/aic7xxx.txt.
244 See Documentation/scsi/aic79xx.txt.
246 amijoy.map= [HW,JOY] Amiga joystick support
247 Map of devices attached to JOY0DAT and JOY1DAT
249 See also Documentation/kernel/input/joystick.txt
251 analog.map= [HW,JOY] Analog joystick and gamepad support
252 Specifies type or capabilities of an analog joystick
253 connected to one of 16 gameports
254 Format: <type1>,<type2>,..<type16>
257 Power management functions (SPARCstation-4/5 + deriv.)
259 Disable APC CPU standby support. SPARCstation-Fox does
260 not play well with APC CPU idle - disable it if you have
261 APC and your system crashes randomly.
263 apic= [APIC,i386] Change the output verbosity whilst booting
264 Format: { quiet (default) | verbose | debug }
265 Change the amount of debugging information output
266 when initialising the APIC and IO-APIC components.
268 apm= [APM] Advanced Power Management
269 See header of arch/i386/kernel/apm.c.
274 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
275 Format: <io>,<irq>,<nodeID>
279 atarimouse= [HW,MOUSE] Atari Mouse
281 atascsi= [HW,SCSI] Atari SCSI
283 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
284 EzKey and similar keyboards
286 atkbd.reset= [HW] Reset keyboard during initialization
288 atkbd.set= [HW] Select keyboard code set
289 Format: <int> (2 = AT (default), 3 = PS/2)
291 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
294 atkbd.softraw= [HW] Choose between synthetic and real raw mode
295 Format: <bool> (0 = real, 1 = synthetic (default))
297 atkbd.softrepeat= [HW]
298 Use software keyboard repeat
302 aztcd= [HW,CD] Aztech CD268 CDROM driver
303 Format: <io>,0x79 (?)
305 baycom_epp= [HW,AX25]
308 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
310 See header of drivers/net/hamradio/baycom_par.c.
312 baycom_ser_fdx= [HW,AX25]
313 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
314 Format: <io>,<irq>,<mode>[,<baud>]
315 See header of drivers/net/hamradio/baycom_ser_fdx.c.
317 baycom_ser_hdx= [HW,AX25]
318 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
319 Format: <io>,<irq>,<mode>
320 See header of drivers/net/hamradio/baycom_ser_hdx.c.
322 blkmtd_device= [HW,MTD]
328 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
329 bttv.radio= Most important insmod options are available as
331 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
332 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
335 See drivers/scsi/BusLogic.c, comment before function
336 BusLogic_ParseDriverOptions().
338 c101= [NET] Moxa C101 synchronous serial card
340 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
341 Sometimes CPU hardware bugs make them report the cache
342 size incorrectly. The kernel will attempt work arounds
343 to fix known problems, but for some CPUs it is not
344 possible to determine what the correct size should be.
345 This option provides an override for these situations.
348 Format: <io>,<irq>[,PAS]
349 See header of drivers/cdrom/cdu31a.c.
351 chandev= [HW,NET] Generic channel device initialisation
353 checkreqprot [SELINUX] Set initial checkreqprot flag value.
354 Format: { "0" | "1" }
355 See security/selinux/Kconfig help text.
356 0 -- check protection applied by kernel (includes
357 any implied execute protection).
358 1 -- check protection requested by application.
359 Default value is set via a kernel config option.
360 Value can be changed at runtime via
361 /selinux/checkreqprot.
363 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
365 Forces specified clocksource (if available) to be used
366 when calculating gettimeofday(). If specified
367 clocksource is not available, it defaults to PIT.
368 Format: { pit | tsc | cyclone | pmtmr }
370 code_bytes [IA32] How many bytes of object code to print in an
377 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
378 over the 8254 in addition to over the IO-APIC. The
379 kernel tries to set a sensible default.
381 hpet= [IA-32,HPET] option to disable HPET and use PIT.
385 Format: { auto | [<io>,][<irq>] }
387 com20020= [HW,NET] ARCnet - COM20020 chipset
389 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
391 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
395 ARCnet - COM90xx chipset (memory-mapped buffers)
396 Format: <io>[,<irq>[,<memstart>]]
398 condev= [HW,S390] console device
401 console= [KNL] Output console device and options.
403 tty<n> Use the virtual console device <n>.
407 Use the specified serial port. The options are of
408 the form "bbbbpnf", where "bbbb" is the baud rate,
409 "p" is parity ("n", "o", or "e"), "n" is number of
410 bits, and "f" is flow control ("r" for RTS or
411 omit it). Default is "9600n8".
413 See Documentation/serial-console.txt for more
415 Documentation/networking/netconsole.txt for an
418 uart,io,<addr>[,options]
419 uart,mmio,<addr>[,options]
420 Start an early, polled-mode console on the 8250/16550
421 UART at the specified I/O port or MMIO address,
422 switching to the matching ttyS device later. The
423 options are the same as for ttyS, above.
425 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
427 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
430 Format: { parport<nr> | auto | none }
432 crashkernel=nn[KMG]@ss[KMG]
433 [KNL] Reserve a chunk of physical memory to
434 hold a kernel to switch to with kexec on panic.
437 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
442 cs89x0_media= [HW,NET]
443 Format: { rj45 | aui | bnc }
445 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
448 See header of drivers/s390/block/dasd_devmap.c.
450 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
451 (one device per port)
452 Format: <port#>,<type>
453 See also Documentation/input/joystick-parport.txt
455 debug [KNL] Enable kernel debugging (events log level).
458 [KNL] verbose self-tests
460 Print debugging info while doing the locking API
462 We default to 0 (no extra messages), setting it to
463 1 will print _a lot_ more information - normally
464 only useful to kernel developers.
467 Format: <area>[,<node>]
468 See also Documentation/networking/decnet.txt.
471 Set number of hash buckets for dentry cache.
474 IO parameters + enable/disable command.
476 digiepca= [HW,SERIAL]
477 See drivers/char/README.epca and
478 Documentation/digiepca.txt.
480 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
482 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
484 dmasound= [HW,OSS] Sound subsystem buffers
490 earlyprintk= [IA-32,X86-64,SH]
492 earlyprintk=serial[,ttySn[,baudrate]]
494 Append ",keep" to not disable it when the real console
497 Only vga or serial at a time, not both.
499 Currently only ttyS0 and ttyS1 are supported.
501 Interaction with the standard serial driver is not
504 The VGA output is eventually overwritten by the real
509 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
512 non-0: interrupt mode (default)
519 Format: {"of[f]" | "sk[ipmbr]"}
520 See comment in arch/i386/boot/edd.S
523 Format: <id>,<membase>,<irq>
525 eisa_irq_edge= [PARISC,HW]
526 See header of drivers/parisc/eisa.c.
529 See comment before function elanfreq_setup() in
530 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
533 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
534 See Documentation/block/as-iosched.txt and
535 Documentation/block/deadline-iosched.txt for details.
537 elfcorehdr= [IA-32, X86_64]
538 Specifies physical address of start of kernel core
539 image elf header. Generally kexec loader will
540 pass this option to capture kernel.
541 See Documentation/kdump/kdump.txt for details.
543 enforcing [SELINUX] Set initial enforcing status.
545 See security/selinux/Kconfig help text.
546 0 -- permissive (log only, no denials).
547 1 -- enforcing (deny and log).
549 Value can be changed at runtime via /selinux/enforce.
552 Format: <spdif>,[<nomix>,[<amplifier>]]
553 See also header of sound/oss/es1371.c.
555 ether= [HW,NET] Ethernet cards parameters
556 This option is obsoleted by the "netdev=" option, which
557 has equivalent usage. See its documentation for details.
559 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
564 fail_make_request=[KNL]
565 General fault injection mechanism.
566 Format: <interval>,<probability>,<space>,<times>
567 See also /Documentation/fault-injection/.
570 See header of drivers/scsi/fd_mcs.c.
573 See header of drivers/scsi/fdomain.c.
576 See Documentation/floppy.txt.
579 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
580 support via parallel port (up to 5 devices per port)
581 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
582 See also Documentation/input/joystick-parport.txt
587 See header of drivers/scsi/gdth.c.
589 gpt [EFI] Forces disk with valid GPT signature but
590 invalid Protective MBR to be treated as GPT.
597 hashdist= [KNL,NUMA] Large hashes allocated during boot
598 are distributed across NUMA nodes. Defaults on
599 for IA-64, off otherwise.
600 Format: 0 | 1 (for off | on)
602 hcl= [IA-64] SGI's Hardware Graph compatibility layer
604 hd= [EIDE] (E)IDE hard drive subsystem geometry
605 Format: <cyl>,<head>,<sect>
607 hd?= [HW] (E)IDE subsystem
608 hd?lun= See Documentation/ide.txt.
610 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
611 size of <nn>. This works even on boxes that have no
612 highmem otherwise. This also works to reduce highmem
613 size on bigger boxes.
615 highres= [KNL] Enable/disable high resolution timer mode.
616 Valid parameters: "on", "off"
620 See Documentation/isdn/README.HiSax.
622 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
624 i8042.direct [HW] Put keyboard port into non-translated mode
625 i8042.dumbkbd [HW] Pretend that controller can only read data from
626 keyboard and cannot control its state
627 (Don't attempt to blink the leds)
628 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
629 i8042.nokbd [HW] Don't check/create keyboard port
630 i8042.nomux [HW] Don't check presence of an active multiplexing
632 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
635 [HW] Frequency with which keyboard LEDs should blink
636 when kernel panics (default is 0.5 sec)
637 i8042.reset [HW] Reset the controller during init and cleanup
638 i8042.unlock [HW] Unlock (ignore) the keylock
642 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
643 indicates that the driver is running on unsupported
645 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
646 does not match list of supported models.
648 [HW] Report power status in /proc/i8k
649 (disabled by default)
650 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
653 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
654 See Documentation/mca.txt.
657 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
659 ide= [HW] (E)IDE subsystem
660 Format: ide=nodma or ide=doubler or ide=reverse
661 See Documentation/ide.txt.
663 ide?= [HW] (E)IDE subsystem
664 Format: ide?=noprobe or chipset specific parameters.
665 See Documentation/ide.txt.
667 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
668 See Documentation/ide.txt.
671 Format: idle=poll or idle=halt
673 ignore_loglevel [KNL]
674 Ignore loglevel setting - this will print /all/
675 kernel messages to the console. Useful for debugging.
678 Set number of hash buckets for inode cache.
681 See header of drivers/scsi/in2000.c.
685 Run specified binary instead of /sbin/init as init
688 initcall_debug [KNL] Trace initcalls as they are executed. Useful
689 for working out where the kernel is dying during
692 initrd= [BOOT] Specify the location of the initial ramdisk
694 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
697 combined_mode= [HW] control which driver uses IDE ports in combined
698 mode: legacy IDE driver, libata, or both
699 (in the libata case, libata.atapi_enabled=1 may be
700 useful as well). Note that using the ide or libata
701 options may affect your device naming (e.g. by
702 changing hdc to sdb).
703 Format: combined (default), ide, or libata
707 io7= [HW] IO7 for Marvel based alpha systems
708 See comment before marvel_specify_io7 in
709 arch/alpha/kernel/core_marvel.c.
712 See Documentation/nfsroot.txt.
714 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
715 See comment before ip2_setup() in drivers/char/ip2.c.
717 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
718 See header of drivers/scsi/ips.c.
720 ports= [IP_VS_FTP] IPVS ftp helper module
722 Up to 8 (IP_VS_APP_MAX_PORTS) ports
724 Format: <port>,<port>....
727 When an interrupt is not handled search all handlers
728 for it. Intended to get systems with badly broken
732 When an interrupt is not handled search all handlers
733 for it. Also check all handlers each timer
734 interrupt. Intended to get systems with badly broken
738 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
740 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
742 <cpu number>,...,<cpu number>
744 <cpu number>-<cpu number> (must be a positive range in ascending order)
746 <cpu number>,...,<cpu number>-<cpu number>
747 This option can be used to specify one or more CPUs
748 to isolate from the general SMP balancing and scheduling
749 algorithms. The only way to move a process onto or off
750 an "isolated" CPU is via the CPU affinity syscalls.
751 <cpu number> begins at 0 and the maximum value is
752 "number of CPUs in system - 1".
754 This option is the preferred way to isolate CPUs. The
755 alternative -- manually setting the CPU mask of all
756 tasks in the system -- can cause problems and
757 suboptimal load balancer performance.
760 Format: <io>,<irq>,<dma>,<setup>
764 js= [HW,JOY] Analog joystick
765 See Documentation/input/joystick.txt.
769 kstack=N [IA-32,X86-64] Print N words from the kernel stack
774 lapic [IA-32,APIC] Enable the local APIC even if BIOS
777 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
778 Format: addr:<io>,irq:<irq>
780 llsc*= [IA64] See function print_params() in
781 arch/ia64/sn/kernel/llsc4.c.
783 load_ramdisk= [RAM] List of ramdisks to load from floppy
784 See Documentation/ramdisk.txt.
786 lockd.nlm_grace_period=P [NFS] Assign grace period.
789 lockd.nlm_tcpport=N [NFS] Assign TCP port.
792 lockd.nlm_timeout=T [NFS] Assign timeout value.
795 lockd.nlm_udpport=M [NFS] Assign UDP port.
798 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
801 loglevel= All Kernel Messages with a loglevel smaller than the
802 console loglevel will be printed to the console. It can
803 also be changed with klogd or other programs. The
804 loglevels are defined as follows:
806 0 (KERN_EMERG) system is unusable
807 1 (KERN_ALERT) action must be taken immediately
808 2 (KERN_CRIT) critical conditions
809 3 (KERN_ERR) error conditions
810 4 (KERN_WARNING) warning conditions
811 5 (KERN_NOTICE) normal but significant condition
812 6 (KERN_INFO) informational
813 7 (KERN_DEBUG) debug-level messages
815 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
816 Format: { n | nk | nM }
817 n must be a power of two. The default size
818 is set in the kernel config file.
820 lp=0 [LP] Specify parallel ports to use, e.g,
821 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
822 lp=reset first parallel port). 'lp=0' disables the
823 lp=auto printer driver. 'lp=reset' (which can be
824 specified in addition to the ports) causes
825 attached printers to be reset. Using
826 lp=port1,port2,... specifies the parallel ports
827 to associate lp devices with, starting with
828 lp0. A port specification may be 'none' to skip
829 that lp device, or a parport name such as
830 'parport0'. Specifying 'lp=auto' instead of a
831 port specification list means that device IDs
832 from each port should be examined, to see if
833 an IEEE 1284-compliant printer is attached; if
834 so, the driver will manage that printer.
835 See also header of drivers/char/lp.c.
838 Sets loops_per_jiffy to given constant, thus avoiding
839 time-consuming boot-time autodetection (up to 250 ms per
840 CPU). 0 enables autodetection (default). To determine
841 the correct value for your kernel, boot with normal
842 autodetection and see what value is printed. Note that
843 on SMP systems the preset will be applied to all CPUs,
844 which is likely to cause problems if your CPUs need
845 significantly divergent settings. An incorrect value
846 will cause delays in the kernel to be wrong, leading to
847 unpredictable I/O errors and other breakage. Although
848 unlikely, in the extreme case this might damage your
852 Format: <io>,<irq>,<dma>
854 mac5380= [HW,SCSI] Format:
855 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
857 mac53c9x= [HW,SCSI] Format:
858 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
860 machvec= [IA64] Force the use of a particular machine-vector
861 (machvec) in a generic kernel.
862 Example: machvec=hpzx1_swiotlb
864 max_loop= [LOOP] Maximum number of loopback devices that can
868 maxcpus= [SMP] Maximum number of processors that an SMP kernel
870 Using "nosmp" or "maxcpus=0" will disable SMP
871 entirely (the MPS table probe still happens, though).
872 A command-line option of "maxcpus=<NUM>", where <NUM>
873 is an integer greater than 0, limits the maximum number
874 of CPUs activated in SMP mode to <NUM>.
875 Using "maxcpus=1" on an SMP kernel is the trivial
876 case of an SMP kernel with only one CPU.
878 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
879 equal to this physical address is ignored.
881 max_luns= [SCSI] Maximum number of LUNs to probe.
882 Should be between 1 and 2^32-1.
885 [SCSI] Maximum number of LUNs received.
886 Should be between 1 and 16384.
888 mca-pentium [BUGS=IA-32]
893 Format: <port>,<irq>,<mitsumi_bug_93_wait>
897 mce [IA-32] Machine Check Exception
899 md= [HW] RAID subsystems devices and level
900 See Documentation/md.txt.
903 Format: <first>,<last>
904 Specifies range of consoles to be captured by the MDA.
906 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
907 Amount of memory to be used when the kernel is not able
908 to see the whole system memory or for test.
909 [IA-32] Use together with memmap= to avoid physical
910 address space collisions. Without memmap= PCI devices
911 could be placed at addresses belonging to unused RAM.
913 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
916 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
917 E820 memory map, as specified by the user.
918 Such memmap=exactmap lines can be constructed based on
919 BIOS output or other requirements. See the memmap=nn@ss
922 memmap=nn[KMG]@ss[KMG]
923 [KNL] Force usage of a specific region of memory
924 Region of memory to be used, from ss to ss+nn.
926 memmap=nn[KMG]#ss[KMG]
927 [KNL,ACPI] Mark specific memory as ACPI data.
928 Region of memory to be used, from ss to ss+nn.
930 memmap=nn[KMG]$ss[KMG]
931 [KNL,ACPI] Mark specific memory as reserved.
932 Region of memory to be used, from ss to ss+nn.
934 meye.*= [HW] Set MotionEye Camera parameters
935 See Documentation/video4linux/meye.txt.
940 [KNL,SMP] debug: override scheduler migration costs
941 Format: <level-1-usecs>,<level-2-usecs>,...
942 This debugging option can be used to override the
943 default scheduler migration cost matrix. The numbers
944 are indexed by 'CPU domain distance'.
945 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
946 box will set up an intra-core migration cost of
947 1 msec, an inter-core migration cost of 2 msecs,
948 and an inter-node migration cost of 3 msecs.
950 WARNING: using the wrong values here can break
951 scheduler performance, so it's only for scheduler
952 development purposes, not production environments.
955 [KNL,SMP] migration cost auto-detect verbosity
957 If a system's migration matrix reported at bootup
958 seems erroneous then this option can be used to
959 increase verbosity of the detection process.
960 We default to 0 (no extra messages), 1 will print
961 some more information, and 2 will be really
962 verbose (probably only useful if you also have a
963 serial console attached to the system).
966 [KNL,SMP] multiply/divide migration costs by a factor
968 This debug option can be used to proportionally
969 increase or decrease the auto-detected migration
970 costs for all entries of the migration matrix.
971 E.g. migration_factor=150 will increase migration
972 costs by 50%. (and thus the scheduler will be less
973 eager migrating cache-hot tasks)
974 migration_factor=80 will decrease migration costs
975 by 20%. (thus the scheduler will be more eager to
978 WARNING: using the wrong values here can break
979 scheduler performance, so it's only for scheduler
980 development purposes, not production environments.
983 [MOUSE] Maximum time between finger touching and
984 leaving touchpad surface for touch to be considered
985 a tap and be reported as a left button click (for
986 touchpads working in absolute mode only).
988 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
989 reporting absolute coordinates, such as tablets
990 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
991 reporting absolute coordinates, such as tablets
997 Format: <name>,<region-number>,<size>,<offset>
999 MTD_Region= [MTD] Format:
1000 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1003 See drivers/mtd/cmdline.c.
1005 mtouchusb.raw_coordinates=
1006 [HW] Make the MicroTouch USB driver use raw coordinates
1007 ('y', default) or cooked coordinates ('n')
1009 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1012 See header of drivers/scsi/NCR_D700.c.
1016 ncr53c400= [HW,SCSI]
1018 ncr53c400a= [HW,SCSI]
1020 ncr53c406a= [HW,SCSI]
1022 ncr53c8xx= [HW,SCSI]
1024 netdev= [NET] Network devices parameters
1025 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1026 Note that mem_start is often overloaded to mean
1027 something different and driver-specific.
1028 This usage is only documented in each driver source
1032 See Documentation/nfsroot.txt.
1034 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1035 See Documentation/nfsroot.txt.
1037 nfs.callback_tcpport=
1038 [NFS] set the TCP port on which the NFSv4 callback
1039 channel should listen.
1041 nfs.idmap_cache_timeout=
1042 [NFS] set the maximum lifetime for idmapper cache
1045 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1047 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1048 emulation library even if a 387 maths coprocessor
1051 noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1055 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1056 the slab allocator. Saves per-node memory, but will
1057 impact performance on real NUMA hardware.
1061 noapic [SMP,APIC] Tells the kernel to not make use of any
1062 IOAPICs that may be present in the system.
1064 noasync [HW,M68K] Disables async and sync negotiation for
1067 nobats [PPC] Do not use BATs for mapping kernel lowmem
1068 on "Classic" PPC cores.
1072 nodelayacct [KNL] Disable per-task delay accounting
1074 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1078 noexec [IA-32,X86-64]
1079 noexec=on: enable non-executable mappings (default)
1080 noexec=off: disable nn-executable mappings
1082 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1083 register save and restore. The kernel will only save
1084 legacy floating-point registers on task switch.
1088 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1089 instruction doesn't work correctly and not to
1092 nohalt [IA-64] Tells the kernel not to use the power saving
1093 function PAL_HALT_LIGHT when idle. This increases
1094 power-consumption. On the positive side, it reduces
1095 interrupt wake-up latency, which may improve performance
1096 in certain environments such as networked servers or
1099 nohz= [KNL] Boottime enable/disable dynamic ticks
1100 Valid arguments: on, off
1103 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1105 noirqdebug [IA-32] Disables the code which attempts to detect and
1106 disable unhandled interrupt sources.
1108 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1109 broken timer IRQ sources.
1111 noisapnp [ISAPNP] Disables ISA PnP code.
1113 noinitrd [RAM] Tells the kernel not to load any configured
1118 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1120 nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
1122 noltlbs [PPC] Do not use large page/tlb entries for kernel
1123 lowmem mapping on PPC40x.
1125 nomca [IA-64] Disable machine check abort handling
1127 nomce [IA-32] Machine Check Exception
1129 noresidual [PPC] Don't use residual data on PReP machines.
1131 noresume [SWSUSP] Disables resume and restores original swap
1134 no-scroll [VGA] Disables scrollback.
1135 This is required for the Braillex ib80-piezo Braille
1136 reader made by F.H. Papenmeier (Germany).
1140 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1142 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1144 nosync [HW,M68K] Disables sync negotiation for all devices.
1146 notsc [BUGS=IA-32] Disable Time Stamp Counter
1148 nousb [USB] Disable the USB subsystem
1152 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1157 opl3sa2= [HW,OSS] Format:
1158 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1160 oprofile.timer= [HW]
1161 Use timer interrupt instead of performance counters
1166 osst= [HW,SCSI] SCSI Tape Driver
1167 Format: <buffer_size>,<write_threshold>
1168 See also Documentation/scsi/st.txt.
1170 panic= [KNL] Kernel behaviour on panic
1173 parkbd.port= [HW] Parallel port number the keyboard adapter is
1174 connected to, default is 0.
1176 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1177 0 for XT, 1 for AT (default is AT).
1180 parport= [HW,PPT] Specify parallel ports. 0 disables.
1181 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1182 Use 'auto' to force the driver to use any
1183 IRQ/DMA settings detected (the default is to
1184 ignore detected IRQ/DMA settings because of
1185 possible conflicts). You can specify the base
1186 address, IRQ, and DMA settings; IRQ and DMA
1187 should be numbers, or 'auto' (for using detected
1188 settings on that particular port), or 'nofifo'
1189 (to avoid using a FIFO even if it is detected).
1190 Parallel ports are assigned in the order they
1191 are specified on the command line, starting
1194 parport_init_mode= [HW,PPT]
1195 Configure VIA parallel port to operate in
1196 a specific mode. This is necessary on Pegasos
1197 computer where firmware has no options for setting
1198 up parallel port mode and sets it to spp.
1199 Currently this function knows 686a and 8231 chips.
1200 Format: [spp|ps2|epp|ecp|ecpepp]
1202 pas2= [HW,OSS] Format:
1203 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1206 See header of drivers/scsi/pas16.c.
1209 Halt all CPUs after the first oops has been printed for
1210 the specified number of seconds. This is to be used if
1211 your oopses keep scrolling off the screen.
1216 See header of drivers/block/paride/pcd.c.
1217 See also Documentation/paride.txt.
1219 pci=option[,option...] [PCI] various PCI subsystem options:
1220 off [IA-32] don't probe for the PCI bus
1221 bios [IA-32] force use of PCI BIOS, don't access
1222 the hardware directly. Use this if your machine
1223 has a non-standard PCI host bridge.
1224 nobios [IA-32] disallow use of PCI BIOS, only direct
1225 hardware access methods are allowed. Use this
1226 if you experience crashes upon bootup and you
1227 suspect they are caused by the BIOS.
1228 conf1 [IA-32] Force use of PCI Configuration
1230 conf2 [IA-32] Force use of PCI Configuration
1232 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1234 nomsi [MSI] If the PCI_MSI kernel config parameter is
1235 enabled, this kernel boot option can be used to
1236 disable the use of MSI interrupts system-wide.
1237 nosort [IA-32] Don't sort PCI devices according to
1238 order given by the PCI BIOS. This sorting is
1239 done to get a device order compatible with
1241 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1242 routing table. These calls are known to be buggy
1243 on several machines and they hang the machine
1244 when used, but on other computers it's the only
1245 way to get the interrupt routing table. Try
1246 this option if the kernel is unable to allocate
1247 IRQs or discover secondary PCI buses on your
1249 rom [IA-32] Assign address space to expansion ROMs.
1250 Use with caution as certain devices share
1251 address decoders between ROMs and other
1253 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1254 assigned automatically to PCI devices. You can
1255 make the kernel exclude IRQs of your ISA cards
1257 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1258 of the PIRQ table (normally generated
1259 by the BIOS) if it is outside the
1260 F0000h-100000h range.
1261 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1262 useful if the kernel is unable to find your
1263 secondary buses and you want to tell it
1264 explicitly which ones they are.
1265 assign-busses [IA-32] Always assign all PCI bus
1266 numbers ourselves, overriding
1267 whatever the firmware may have done.
1268 usepirqmask [IA-32] Honor the possible IRQ mask stored
1269 in the BIOS $PIR table. This is needed on
1270 some systems with broken BIOSes, notably
1271 some HP Pavilion N5400 and Omnibook XE3
1272 notebooks. This will have no effect if ACPI
1273 IRQ routing is enabled.
1274 noacpi [IA-32] Do not use ACPI for IRQ routing
1275 or for PCI scanning.
1276 routeirq Do IRQ routing for all PCI devices.
1277 This is normally done in pci_enable_device(),
1278 so this option is a temporary workaround
1279 for broken drivers that don't call it.
1280 firmware [ARM] Do not re-enumerate the bus but instead
1281 just use the configuration from the
1282 bootloader. This is currently used on
1283 IXP2000 systems where the bus has to be
1284 configured a certain way for adjunct CPUs.
1285 noearly [X86] Don't do any early type 1 scanning.
1286 This might help on some broken boards which
1287 machine check when some devices' config space
1288 is read. But various workarounds are disabled
1289 and some IOMMU drivers will not work.
1290 bfsort Sort PCI devices into breadth-first order.
1291 This sorting is done to get a device
1292 order compatible with older (<= 2.4) kernels.
1293 nobfsort Don't sort PCI devices into breadth-first order.
1294 cbiosize=nn[KMG] The fixed amount of bus space which is
1295 reserved for the CardBus bridge's IO window.
1296 The default value is 256 bytes.
1297 cbmemsize=nn[KMG] The fixed amount of bus space which is
1298 reserved for the CardBus bridge's memory
1299 window. The default value is 64 megabytes.
1301 pcmv= [HW,PCMCIA] BadgePAD 4
1304 See Documentation/paride.txt.
1306 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1309 See arch/parisc/kernel/pdc_chassis.c
1312 See Documentation/paride.txt.
1315 See Documentation/paride.txt.
1317 pirq= [SMP,APIC] Manual mp-table setup
1318 See Documentation/i386/IO-APIC.txt.
1320 plip= [PPT,NET] Parallel port network link
1321 Format: { parport<nr> | timid | 0 }
1322 See also Documentation/parport.txt.
1328 { on | off | curr | res | no-curr | no-res }
1331 [ISAPNP] Exclude IRQs for the autoconfiguration
1334 [ISAPNP] Exclude DMAs for the autoconfiguration
1336 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1337 Ranges are in pairs (I/O port base and size).
1340 [ISAPNP] Exclude memory regions for the
1342 Ranges are in pairs (memory base and size).
1344 profile= [KNL] Enable kernel profiling via /proc/profile
1345 Format: [schedule,]<number>
1346 Param: "schedule" - profile schedule points.
1347 Param: <number> - step/bucket size as a power of 2 for
1348 statistical time based profiling.
1349 Param: "sleep" - profile D-state sleeping (millisecs)
1351 processor.max_cstate= [HW,ACPI]
1352 Limit processor to maximum C-state
1353 max_cstate=9 overrides any DMI blacklist limit.
1355 processor.nocst [HW,ACPI]
1356 Ignore the _CST method to determine C-states,
1357 instead using the legacy FADT method
1359 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1361 See Documentation/ramdisk.txt.
1363 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1364 probe for; one of (bare|imps|exps|lifebook|any).
1365 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1367 psmouse.resetafter= [HW,MOUSE]
1368 Try to reset the device after so many bad packets
1371 [HW,MOUSE] Set desired mouse resolution, in dpi.
1372 psmouse.smartscroll=
1373 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1374 0 = disabled, 1 = enabled (default).
1376 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1378 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1381 See Documentation/paride.txt.
1383 quiet [KNL] Disable most log messages
1388 See Documentation/md.txt.
1390 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1391 See Documentation/ramdisk.txt.
1393 ramdisk_blocksize= [RAM]
1394 See Documentation/ramdisk.txt.
1396 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1397 New name for the ramdisk parameter.
1398 See Documentation/ramdisk.txt.
1400 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1401 RCU callbacks to process in one batch.
1403 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1404 RCU callbacks over which batch limiting is disabled.
1406 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1407 RCU callbacks below which batch limiting is re-enabled.
1411 Run specified binary instead of /init from the ramdisk,
1412 used for early userspace startup. See initrd.
1414 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1415 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1416 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1418 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1422 Reserves a hole at the top of the kernel virtual
1425 reset_devices [KNL] Force drivers to reset the underlying device
1426 during initialization.
1429 Specify the partition device for software suspend
1431 resume_offset= [SWSUSP]
1432 Specify the offset from the beginning of the partition
1433 given by "resume=" at which the swap header is located,
1434 in <PAGE_SIZE> units (needed only for swap files).
1435 See Documentation/power/swsusp-and-swap-files.txt
1437 retain_initrd [RAM] Keep initrd memory after extraction
1439 rhash_entries= [KNL,NET]
1440 Set number of hash buckets for route cache
1442 riscom8= [HW,SERIAL]
1443 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1445 ro [KNL] Mount root device read-only on boot
1447 root= [KNL] Root filesystem
1449 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1450 mount the root filesystem
1452 rootflags= [KNL] Set root filesystem mount option string
1454 rootfstype= [KNL] Set root filesystem type
1456 rw [KNL] Mount root device read-write on boot
1458 S [KNL] Run init in single mode
1461 See drivers/net/irda/sa1100_ir.c.
1464 Format: <io>,<irq>,<dma>,<dma2>
1466 sbni= [NET] Granch SBNI12 leased line adapter
1468 sbpcd= [HW,CD] Soundblaster CD adapter
1470 See a comment before function sbpcd_setup() in
1471 drivers/cdrom/sbpcd.c.
1473 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1474 Format: <io>[,<timeout>[,<isapnp>]]
1476 scsi_debug_*= [SCSI]
1477 See drivers/scsi/scsi_debug.c.
1479 scsi_default_dev_flags=
1480 [SCSI] SCSI default device flags
1483 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1484 Format: <vendor>:<model>:<flags>
1485 (flags are integer value)
1487 scsi_logging= [SCSI]
1489 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1490 discovered. async scans them in kernel threads,
1491 allowing boot to proceed. none ignores them, expecting
1492 user space to do the scan.
1494 selinux [SELINUX] Disable or enable SELinux at boot time.
1495 Format: { "0" | "1" }
1496 See security/selinux/Kconfig help text.
1499 Default value is set via kernel config option.
1500 If enabled at boot time, /selinux/disable can be used
1501 later to disable prior to initial policy load.
1503 selinux_compat_net =
1504 [SELINUX] Set initial selinux_compat_net flag value.
1505 Format: { "0" | "1" }
1506 0 -- use new secmark-based packet controls
1507 1 -- use legacy packet controls
1508 Default value is 0 (preferred).
1509 Value can be changed at runtime via
1510 /selinux/compat_net.
1512 serialnumber [BUGS=IA-32]
1514 sg_def_reserved_size= [SCSI]
1517 Maximal number of shapers.
1520 See header of drivers/scsi/sim710.c.
1526 Format: <io>,<irq>,<dma>
1527 See header of drivers/cdrom/sjcd.c.
1532 Format: <io1>[,<io2>[,...,<io8>]]
1534 snd-ad1816a= [HW,ALSA]
1536 snd-ad1848= [HW,ALSA]
1538 snd-ali5451= [HW,ALSA]
1540 snd-als100= [HW,ALSA]
1542 snd-als4000= [HW,ALSA]
1544 snd-azt2320= [HW,ALSA]
1546 snd-cmi8330= [HW,ALSA]
1548 snd-cmipci= [HW,ALSA]
1550 snd-cs4231= [HW,ALSA]
1552 snd-cs4232= [HW,ALSA]
1554 snd-cs4236= [HW,ALSA]
1556 snd-cs4281= [HW,ALSA]
1558 snd-cs46xx= [HW,ALSA]
1560 snd-dt019x= [HW,ALSA]
1562 snd-dummy= [HW,ALSA]
1564 snd-emu10k1= [HW,ALSA]
1566 snd-ens1370= [HW,ALSA]
1568 snd-ens1371= [HW,ALSA]
1570 snd-es968= [HW,ALSA]
1572 snd-es1688= [HW,ALSA]
1574 snd-es18xx= [HW,ALSA]
1576 snd-es1938= [HW,ALSA]
1578 snd-es1968= [HW,ALSA]
1580 snd-fm801= [HW,ALSA]
1582 snd-gusclassic= [HW,ALSA]
1584 snd-gusextreme= [HW,ALSA]
1586 snd-gusmax= [HW,ALSA]
1590 snd-ice1712= [HW,ALSA]
1592 snd-intel8x0= [HW,ALSA]
1594 snd-interwave= [HW,ALSA]
1599 snd-korg1212= [HW,ALSA]
1601 snd-maestro3= [HW,ALSA]
1603 snd-mpu401= [HW,ALSA]
1605 snd-mtpav= [HW,ALSA]
1607 snd-nm256= [HW,ALSA]
1609 snd-opl3sa2= [HW,ALSA]
1617 snd-opti93x= [HW,ALSA]
1621 snd-rme32= [HW,ALSA]
1623 snd-rme96= [HW,ALSA]
1625 snd-rme9652= [HW,ALSA]
1631 snd-sbawe= [HW,ALSA]
1633 snd-serial= [HW,ALSA]
1635 snd-sgalaxy= [HW,ALSA]
1637 snd-sonicvibes= [HW,ALSA]
1642 snd-sun-cs4231= [HW,ALSA]
1644 snd-trident= [HW,ALSA]
1646 snd-usb-audio= [HW,ALSA,USB]
1648 snd-via82xx= [HW,ALSA]
1650 snd-virmidi= [HW,ALSA]
1652 snd-wavefront= [HW,ALSA]
1654 snd-ymfpci= [HW,ALSA]
1657 Format: <io>[,<irq>]
1659 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1660 See Documentation/sonypi.txt
1662 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1663 See Documentation/specialix.txt.
1665 spia_io_base= [HW,MTD]
1671 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1673 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1674 See Documentation/scsi/st.txt.
1677 See header of drivers/scsi/seagate.c.
1681 Set the STI (builtin display/keyboard on the HP-PARISC
1682 machines) console (graphic card) which should be used
1683 as the initial boot-console.
1684 See also comment in drivers/video/console/sticore.c.
1687 See comment in drivers/video/console/sticore.c.
1690 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1694 Control how the NFS server code allocates CPUs to
1695 service thread pools. Depending on how many NICs
1696 you have and where their interrupts are bound, this
1697 option will affect which CPUs will do NFS serving.
1698 Note: this parameter cannot be changed while the
1699 NFS server is running.
1701 auto the server chooses an appropriate mode
1702 automatically using heuristics
1703 global a single global pool contains all CPUs
1704 percpu one pool for each CPU
1705 pernode one pool for each NUMA node (equivalent
1706 to global on non-NUMA machines)
1708 swiotlb= [IA-64] Number of I/O TLB slabs
1712 sym53c416= [HW,SCSI]
1713 See header of drivers/scsi/sym53c416.c.
1715 sysrq_always_enabled
1717 Ignore sysrq setting - this boot parameter will
1718 neutralize any effect of /proc/sys/kernel/sysrq.
1719 Useful for debugging.
1722 See header of drivers/scsi/t128.c.
1726 thash_entries= [KNL,NET]
1727 Set number of hash buckets for TCP connection
1729 time Show timing data prefixed to each printk message line
1731 clocksource= [GENERIC_TIME] Override the default clocksource
1732 Override the default clocksource and use the clocksource
1733 with the name specified.
1735 tipar.timeout= [HW,PPT]
1736 Set communications timeout in tenths of a second
1739 tipar.delay= [HW,PPT]
1740 Set inter-bit delay in microseconds (default 10).
1743 See header of drivers/scsi/seagate.c.
1746 See comment before function dc390_setup() in
1747 drivers/scsi/tmscsim.c.
1751 trix= [HW,OSS] MediaTrix AudioTrix Pro
1753 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1755 tsdev.xres= [TS] Horizontal screen resolution.
1756 tsdev.yres= [TS] Vertical screen resolution.
1758 turbografx.map[2|3]= [HW,JOY]
1759 TurboGraFX parallel port interface
1761 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1762 See also Documentation/input/joystick-parport.txt
1764 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1765 See header of drivers/scsi/u14-34f.c.
1774 [USB] Ignore overcurrent events (default N).
1775 Some badly-designed motherboards generate lots of
1776 bogus events, for ports that aren't wired to
1777 anything. Set this parameter to avoid log spamming.
1778 Note that genuine overcurrent events won't be
1781 usbcore.autosuspend=
1782 [USB] The autosuspend time delay (in seconds) used
1783 for newly-detected USB devices (default 2). This
1784 is the time required before an idle device will be
1785 autosuspended. Devices for which the delay is set
1786 to 0 won't be autosuspended at all.
1789 [USBHID] The interval which mice are to be polled at.
1792 vdso=1: enable VDSO (default)
1793 vdso=0: disable VDSO mapping
1795 video= [FB] Frame buffer configuration
1796 See Documentation/fb/modedb.txt.
1798 vga= [BOOT,IA-32] Select a particular video mode
1799 See Documentation/i386/boot.txt and
1800 Documentation/svga.txt.
1801 Use vga=ask for menu.
1802 This is actually a boot loader parameter; the value is
1803 passed to the kernel using a special protocol.
1805 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1806 size of <nn>. This can be used to increase the
1807 minimum size (128MB on x86). It can also be used to
1808 decrease the size and leave more room for directly
1811 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1814 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1817 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1820 waveartist= [HW,OSS]
1821 Format: <io>,<irq>,<dma>,<dma2>
1824 See header of drivers/scsi/wd33c93.c.
1827 See header of drivers/scsi/wd7000.c.
1830 See Documentation/watchdog/watchdog.txt.
1832 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1833 xd_geo= See header of drivers/block/xd.c.
1835 xirc2ps_cs= [NET,PCMCIA]
1837 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1839 norandmaps Don't use address space randomization
1840 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1842 unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
1843 This is useful to get more information why
1844 you got a "dwarf2 unwinder stuck"
1846 ______________________________________________________________________
1850 Add documentation for ALSA options.
1851 Add more DRM drivers.