1 February 2003 Kernel Parameters v2.5.59
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 The text in square brackets at the beginning of the description state the
21 restrictions on the kernel for the said kernel parameter to be valid. The
22 restrictions referred to are that the relevant option is valid if:
24 ACPI ACPI support is enabled.
25 ALSA ALSA sound support is enabled.
26 APIC APIC support is enabled.
27 APM Advanced Power Management support is enabled.
28 AX25 Appropriate AX.25 support is enabled.
29 CD Appropriate CD support is enabled.
30 DEVFS devfs support is enabled.
31 DRM Direct Rendering Management support is enabled.
32 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
33 EFI EFI Partitioning (GPT) is enabled
34 EIDE EIDE/ATAPI support is enabled.
35 FB The frame buffer device is enabled.
36 HW Appropriate hardware is enabled.
37 IA-32 IA-32 aka i386 architecture is enabled.
38 IA-64 IA-64 architecture is enabled.
39 IOSCHED More than one I/O scheduler is enabled.
40 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
41 ISAPNP ISA PnP code is enabled.
42 ISDN Appropriate ISDN support is enabled.
43 JOY Appropriate joystick support is enabled.
44 LP Printer support is enabled.
45 LOOP Loopback device support is enabled.
46 M68k M68k architecture is enabled.
47 These options have more detailed description inside of
48 Documentation/m68k/kernel-options.txt.
49 MCA MCA bus support is enabled.
50 MDA MDA console support is enabled.
51 MOUSE Appropriate mouse support is enabled.
52 MTD MTD support is enabled.
53 NET Appropriate network support is enabled.
54 NUMA NUMA support is enabled.
55 NFS Appropriate NFS support is enabled.
56 OSS OSS sound support is enabled.
57 PARIDE The ParIDE subsystem is enabled.
58 PARISC The PA-RISC architecture is enabled.
59 PCI PCI bus support is enabled.
60 PCMCIA The PCMCIA subsystem is enabled.
61 PNP Plug & Play support is enabled.
62 PPC PowerPC architecture is enabled.
63 PPT Parallel port support is enabled.
64 PS2 Appropriate PS/2 support is enabled.
65 RAM RAM disk support is enabled.
66 S390 S390 architecture is enabled.
67 SCSI Appropriate SCSI support is enabled.
68 A lot of drivers has their options described inside of
70 SELINUX SELinux support is enabled.
71 SERIAL Serial support is enabled.
72 SMP The kernel is an SMP kernel.
73 SPARC Sparc architecture is enabled.
74 SWSUSP Software suspension is enabled.
75 TS Appropriate touchscreen support is enabled.
76 USB USB support is enabled.
77 USBHID USB Human Interface Device support is enabled.
78 V4L Video For Linux support is enabled.
79 VGA The VGA console has been enabled.
80 VT Virtual terminal support is enabled.
81 WDT Watchdog support is enabled.
82 XT IBM PC/XT MFM hard disk support is enabled.
83 X86-64 X86-64 architecture is enabled.
84 More X86-64 boot options can be found in
85 Documentation/x86_64/boot-options.txt .
87 In addition, the following text indicates that the option:
89 BUGS= Relates to possible processor bugs on the said processor.
90 KNL Is a kernel start-up parameter.
91 BOOT Is a boot loader parameter.
93 Parameters denoted with BOOT are actually interpreted by the boot
94 loader, and have no meaning to the kernel directly.
95 Do not modify the syntax of boot loader parameters without extreme
96 need or coordination with <Documentation/i386/boot.txt>.
98 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
99 a trailing = on the name of any parameter states that that parameter will
100 be entered as an environment variable, whereas its absence indicates that
101 it will appear as a kernel argument readable via /proc/cmdline by programs
102 running once the system is up.
104 53c7xx= [HW,SCSI] Amiga SCSI controllers
105 See header of drivers/scsi/53c7xx.c.
106 See also Documentation/scsi/ncr53c7xx.txt.
108 acpi= [HW,ACPI] Advanced Configuration and Power Interface
109 Format: { force | off | ht | strict }
110 force -- enable ACPI if default was off
111 off -- disable ACPI if default was on
112 noirq -- do not use ACPI for IRQ routing
113 ht -- run only enough ACPI to enable Hyper Threading
114 strict -- Be less tolerant of platforms that are not
115 strictly ACPI specification compliant.
117 See also Documentation/pm.txt, pci=noacpi
119 acpi_sleep= [HW,ACPI] Sleep options
120 Format: { s3_bios, s3_mode }
121 See Documentation/power/video.txt
123 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
124 Format: { level | edge | high | low }
126 acpi_irq_balance [HW,ACPI] ACPI will balance active IRQs
129 acpi_irq_nobalance [HW,ACPI] ACPI will not move active IRQs (default)
132 acpi_irq_pci= [HW,ACPI] If irq_balance, Clear listed IRQs for use by PCI
133 Format: <irq>,<irq>...
135 acpi_irq_isa= [HW,ACPI] If irq_balance, Mark listed IRQs used by ISA
136 Format: <irq>,<irq>...
138 acpi_osi= [HW,ACPI] empty param disables _OSI
140 acpi_serialize [HW,ACPI] force serialization of AML methods
142 acpi_skip_timer_override [HW,ACPI]
143 Recognize and ignore IRQ0/pin2 Interrupt Override.
144 For broken nForce2 BIOS resulting in XT-PIC timer.
146 acpi_dbg_layer= [HW,ACPI]
148 Each bit of the <int> indicates an acpi debug layer,
149 1: enable, 0: disable. It is useful for boot time
150 debugging. After system has booted up, it can be set
151 via /proc/acpi/debug_layer.
153 acpi_dbg_level= [HW,ACPI]
155 Each bit of the <int> indicates an acpi debug level,
156 1: enable, 0: disable. It is useful for boot time
157 debugging. After system has booted up, it can be set
158 via /proc/acpi/debug_level.
160 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
162 acpi_generic_hotkey [HW,ACPI]
163 Allow consolidated generic hotkey driver to
164 over-ride platform specific driver.
165 See also Documentation/acpi-hotkey.txt.
168 Format: <io>,<irq>,<dma>,<dma2>
169 See also Documentation/sound/oss/AD1816.
172 Format: <io>,<irq>,<dma>,<dma2>,<type>
178 See header of drivers/scsi/advansys.c.
180 advwdt= [HW,WDT] Advantech WDT
181 Format: <iostart>,<iostop>
183 aedsp16= [HW,OSS] Audio Excel DSP 16
184 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
185 See also header of sound/oss/aedsp16.c.
188 See Documentation/scsi/aha152x.txt.
191 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
194 See Documentation/scsi/aic7xxx.txt.
197 See Documentation/scsi/aic79xx.txt.
200 Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
201 See also header of drivers/scsi/AM53C974.c.
203 amijoy.map= [HW,JOY] Amiga joystick support
204 Map of devices attached to JOY0DAT and JOY1DAT
206 See also Documentation/kernel/input/joystick.txt
208 analog.map= [HW,JOY] Analog joystick and gamepad support
209 Specifies type or capabilities of an analog joystick
210 connected to one of 16 gameports
211 Format: <type1>,<type2>,..<type16>
213 apc= [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
215 Disable APC CPU standby support. SPARCstation-Fox does
216 not play well with APC CPU idle - disable it if you have
217 APC and your system crashes randomly.
219 apic= [APIC,i386] Change the output verbosity whilst booting
220 Format: { quiet (default) | verbose | debug }
221 Change the amount of debugging information output
222 when initialising the APIC and IO-APIC components.
224 apm= [APM] Advanced Power Management
225 See header of arch/i386/kernel/apm.c.
230 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
231 Format: <io>,<irq>,<nodeID>
235 atarimouse= [HW,MOUSE] Atari Mouse
237 atascsi= [HW,SCSI] Atari SCSI
239 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
240 EzKey and similar keyboards
242 atkbd.reset= [HW] Reset keyboard during initialization
244 atkbd.set= [HW] Select keyboard code set
245 Format: <int> (2 = AT (default) 3 = PS/2)
247 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
250 atkbd.softraw= [HW] Choose between synthetic and real raw mode
251 Format: <bool> (0 = real, 1 = synthetic (default))
254 [HW] Use software keyboard repeat
258 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
259 Format: <io>,<memsize>,<isapnp>
261 aztcd= [HW,CD] Aztech CD268 CDROM driver
262 Format: <io>,0x79 (?)
264 baycom_epp= [HW,AX25]
267 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
269 See header of drivers/net/hamradio/baycom_par.c.
271 baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
272 Format: <io>,<irq>,<mode>[,<baud>]
273 See header of drivers/net/hamradio/baycom_ser_fdx.c.
275 baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
276 Format: <io>,<irq>,<mode>
277 See header of drivers/net/hamradio/baycom_ser_hdx.c.
279 blkmtd_device= [HW,MTD]
285 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
286 bttv.radio= Most important insmod options are available as kernel args too.
287 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
288 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
291 See drivers/scsi/BusLogic.c, comment before function
292 BusLogic_ParseDriverOptions().
294 c101= [NET] Moxa C101 synchronous serial card
296 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
297 Sometimes CPU hardware bugs make them report the cache
298 size incorrectly. The kernel will attempt work arounds
299 to fix known problems, but for some CPUs it is not
300 possible to determine what the correct size should be.
301 This option provides an override for these situations.
304 Format: <io>,<irq>[,PAS]
305 See header of drivers/cdrom/cdu31a.c.
307 chandev= [HW,NET] Generic channel device initialisation
309 checkreqprot [SELINUX] Set initial checkreqprot flag value.
310 Format: { "0" | "1" }
311 See security/selinux/Kconfig help text.
312 0 -- check protection applied by kernel (includes any implied execute protection).
313 1 -- check protection requested by application.
314 Default value is set via a kernel config option.
315 Value can be changed at runtime via /selinux/checkreqprot.
317 clock= [BUGS=IA-32, HW] gettimeofday timesource override.
318 Forces specified timesource (if avaliable) to be used
319 when calculating gettimeofday(). If specicified timesource
320 is not avalible, it defaults to PIT.
321 Format: { pit | tsc | cyclone | pmtmr }
323 hpet= [IA-32,HPET] option to disable HPET and use PIT.
327 Format: { auto | [<io>,][<irq>] }
329 com20020= [HW,NET] ARCnet - COM20020 chipset
330 Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
332 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
335 com90xx= [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
336 Format: <io>[,<irq>[,<memstart>]]
338 condev= [HW,S390] console device
341 console= [KNL] Output console device and options.
343 tty<n> Use the virtual console device <n>.
346 Use the specified serial port. The options are of
347 the form "bbbbpn", where "bbbb" is the baud rate,
348 "p" is parity ("n", "o", or "e"), and "n" is bits.
351 See also Documentation/serial-console.txt.
353 uart,io,<addr>[,options]
354 uart,mmio,<addr>[,options]
355 Start an early, polled-mode console on the 8250/16550
356 UART at the specified I/O port or MMIO address,
357 switching to the matching ttyS device later. The
358 options are the same as for ttyS, above.
360 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
361 Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
364 Format: { parport<nr> | auto | none }
366 crashkernel=nn[KMG]@ss[KMG]
367 [KNL] Reserve a chunk of physical memory to
368 hold a kernel to switch to with kexec on panic.
371 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
376 cs89x0_media= [HW,NET]
377 Format: { rj45 | aui | bnc }
379 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
382 See header of drivers/s390/block/dasd_devmap.c.
384 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
385 (one device per port)
386 Format: <port#>,<type>
387 See also Documentation/input/joystick-parport.txt
389 debug [KNL] Enable kernel debugging (events log level).
392 Format: <area>[,<node>]
393 See also Documentation/networking/decnet.txt.
396 See Documentation/filesystems/devfs/boot-options.
399 Set number of hash buckets for dentry cache.
402 IO parameters + enable/disable command.
404 digiepca= [HW,SERIAL]
405 See drivers/char/README.epca and
406 Documentation/digiepca.txt.
408 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
410 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
412 dmasound= [HW,OSS] Sound subsystem buffers
418 earlyprintk= [IA-32, X86-64]
420 earlyprintk=serial[,ttySn[,baudrate]]
422 Append ,keep to not disable it when the real console
425 Only vga or serial at a time, not both.
427 Currently only ttyS0 and ttyS1 are supported.
429 Interaction with the standard serial driver is not
432 The VGA output is eventually overwritten by the real
442 Format: {"of[f]" | "sk[ipmbr]"}
443 See comment in arch/i386/boot/edd.S
446 Format: <id>,<membase>,<irq>
448 eisa_irq_edge= [PARISC,HW]
449 See header of drivers/parisc/eisa.c.
452 See comment before function elanfreq_setup() in
453 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
456 Format: {"as"|"cfq"|"deadline"|"noop"}
457 See Documentation/block/as-iosched.txt
458 and Documentation/block/deadline-iosched.txt for details.
460 Specifies physical address of start of kernel core image
462 See Documentation/kdump.txt for details.
464 enforcing [SELINUX] Set initial enforcing status.
466 See security/selinux/Kconfig help text.
467 0 -- permissive (log only, no denials).
468 1 -- enforcing (deny and log).
470 Value can be changed at runtime via /selinux/enforce.
473 Format: <lineout>[,<micbias>]
474 See also header of sound/oss/es1370.c.
477 Format: <spdif>,[<nomix>,[<amplifier>]]
478 See also header of sound/oss/es1371.c.
480 ether= [HW,NET] Ethernet cards parameters
481 This option is obsoleted by the "netdev=" option, which
482 has equivalent usage. See its documentation for details.
484 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
488 See header of drivers/scsi/fd_mcs.c.
491 See header of drivers/scsi/fdomain.c.
494 See Documentation/floppy.txt.
496 ftape= [HW] Floppy Tape subsystem debugging options.
497 See Documentation/ftape.txt.
500 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
501 support via parallel port (up to 5 devices per port)
502 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
503 See also Documentation/input/joystick-parport.txt
508 See header of drivers/scsi/gdth.c.
510 gpt [EFI] Forces disk with valid GPT signature but
511 invalid Protective MBR to be treated as GPT.
516 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
519 Format: <io>,<irq>,<dma>,<dma16>
523 hashdist= [KNL,NUMA] Large hashes allocated during boot
524 are distributed across NUMA nodes. Defaults on
525 for IA-64, off otherwise.
527 hcl= [IA-64] SGI's Hardware Graph compatibility layer
529 hd= [EIDE] (E)IDE hard drive subsystem geometry
530 Format: <cyl>,<head>,<sect>
532 hd?= [HW] (E)IDE subsystem
533 hd?lun= See Documentation/ide.txt.
535 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
536 size of <nn>. This works even on boxes that have no
537 highmem otherwise. This also works to reduce highmem
538 size on bigger boxes.
541 See Documentation/isdn/README.HiSax.
543 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
545 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
547 i8042.direct [HW] Put keyboard port into non-translated mode
548 i8042.dumbkbd [HW] Pretend that controlled can only read data from
549 keyboard and can not control its state
550 (Don't attempt to blink the leds)
551 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
552 i8042.nokbd [HW] Don't check/create keyboard port
553 i8042.nomux [HW] Don't check presence of an active multiplexing
555 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
558 [HW] Frequency with which keyboard LEDs should blink
559 when kernel panics (default is 0.5 sec)
560 i8042.reset [HW] Reset the controller during init and cleanup
561 i8042.unlock [HW] Unlock (ignore) the keylock
565 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
566 indicates that the driver is running on unsupported
568 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
569 does not match list of supported models.
571 [HW] Report power status in /proc/i8k
572 (disabled by default)
573 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
576 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
577 See Documentation/mca.txt.
580 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
582 ide= [HW] (E)IDE subsystem
583 Format: ide=nodma or ide=doubler or ide=reverse
584 See Documentation/ide.txt.
586 ide?= [HW] (E)IDE subsystem
587 Format: ide?=noprobe or chipset specific parameters.
588 See Documentation/ide.txt.
590 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
591 See Documentation/ide.txt.
594 Format: idle=poll or idle=halt
597 Set number of hash buckets for inode cache.
600 See header of drivers/scsi/in2000.c.
604 Run specified binary instead of /sbin/init as init
607 initcall_debug [KNL] Trace initcalls as they are executed. Useful
608 for working out where the kernel is dying during
611 initrd= [BOOT] Specify the location of the initial ramdisk
613 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
618 io7= [HW] IO7 for Marvel based alpha systems
619 See comment before marvel_specify_io7 in
620 arch/alpha/kernel/core_marvel.c.
623 See Documentation/nfsroot.txt.
625 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
626 See comment before ip2_setup() in drivers/char/ip2.c.
628 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
629 See header of drivers/scsi/ips.c.
632 When an interrupt is not handled search all handlers
633 for it. Intended to get systems with badly broken
637 When an interrupt is not handled search all handlers
638 for it. Also check all handlers each timer
639 interrupt. Intended to get systems with badly broken
643 Format: <RDP>, <reset>, <pci_scan>, <verbosity>
645 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
646 Format: <cpu number>,...,<cpu number>
647 This option can be used to specify one or more CPUs
648 to isolate from the general SMP balancing and scheduling
649 algorithms. The only way to move a process onto or off
650 an "isolated" CPU is via the CPU affinity syscalls.
651 <cpu number> begins at 0 and the maximum value is
652 "number of CPUs in system - 1".
654 This option is the preferred way to isolate CPUs. The
655 alternative - manually setting the CPU mask of all tasks
656 in the system can cause problems and suboptimal load
657 balancer performance.
660 Format: <io>,<irq>,<dma>,<setup>
664 js= [HW,JOY] Analog joystick
665 See Documentation/input/joystick.txt.
669 kstack=N [IA-32, X86-64] Print N words from the kernel stack
674 lapic [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
676 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
677 Format: addr:<io>,irq:<irq>
680 See function print_params() in arch/ia64/sn/kernel/llsc4.c.
682 load_ramdisk= [RAM] List of ramdisks to load from floppy
683 See Documentation/ramdisk.txt.
689 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
692 loglevel= All Kernel Messages with a loglevel smaller than the
693 console loglevel will be printed to the console. It can
694 also be changed with klogd or other programs. The
695 loglevels are defined as follows:
697 0 (KERN_EMERG) system is unusable
698 1 (KERN_ALERT) action must be taken immediately
699 2 (KERN_CRIT) critical conditions
700 3 (KERN_ERR) error conditions
701 4 (KERN_WARNING) warning conditions
702 5 (KERN_NOTICE) normal but significant condition
703 6 (KERN_INFO) informational
704 7 (KERN_DEBUG) debug-level messages
706 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
707 Format is n, nk, nM. n must be a power of two. The
708 default is set in kernel config.
710 lp=0 [LP] Specify parallel ports to use, e.g,
711 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
712 lp=reset first parallel port). 'lp=0' disables the
713 lp=auto printer driver. 'lp=reset' (which can be
714 specified in addition to the ports) causes
715 attached printers to be reset. Using
716 lp=port1,port2,... specifies the parallel ports
717 to associate lp devices with, starting with
718 lp0. A port specification may be 'none' to skip
719 that lp device, or a parport name such as
720 'parport0'. Specifying 'lp=auto' instead of a
721 port specification list means that device IDs
722 from each port should be examined, to see if
723 an IEEE 1284-compliant printer is attached; if
724 so, the driver will manage that printer.
725 See also header of drivers/char/lp.c.
728 Sets loops_per_jiffy to given constant, thus avoiding
729 time-consuming boot-time autodetection (up to 250 ms per
730 CPU). 0 enables autodetection (default). To determine
731 the correct value for your kernel, boot with normal
732 autodetection and see what value is printed. Note that
733 on SMP systems the preset will be applied to all CPUs,
734 which is likely to cause problems if your CPUs need
735 significantly divergent settings. An incorrect value
736 will cause delays in the kernel to be wrong, leading to
737 unpredictable I/O errors and other breakage. Although
738 unlikely, in the extreme case this might damage your
742 Format: <io>,<irq>,<dma>
745 Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
748 Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
751 Force the use of a particular machine-vector (machvec) in a generic
752 kernel. Example: machvec=hpzx1_swiotlb
755 Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
760 max_loop= [LOOP] Maximum number of loopback devices that can
764 maxcpus= [SMP] Maximum number of processors that an SMP kernel
767 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
768 equal to this physical address is ignored.
770 max_luns= [SCSI] Maximum number of LUNs to probe
771 Should be between 1 and 2^32-1.
774 [SCSI] Maximum number of LUNs received
775 Should be between 1 and 16384.
777 mca-pentium [BUGS=IA-32]
782 Format: <port>,<irq>,<mitsumi_bug_93_wait>
786 mce [IA-32] Machine Check Exception
788 md= [HW] RAID subsystems devices and level
789 See Documentation/md.txt.
792 Format: <first>,<last>
793 Specifies range of consoles to be captured by the MDA.
795 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
796 Amount of memory to be used when the kernel is not able
797 to see the whole system memory or for test.
798 [IA-32] Use together with memmap= to avoid physical
799 address space collisions. Without memmap= PCI devices
800 could be placed at addresses belonging to unused RAM.
802 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
805 memmap=exactmap [KNL,IA-32] Enable setting of an exact
806 E820 memory map, as specified by the user.
807 Such memmap=exactmap lines can be constructed based on
808 BIOS output or other requirements. See the memmap=nn@ss
811 memmap=nn[KMG]@ss[KMG]
812 [KNL] Force usage of a specific region of memory
813 Region of memory to be used, from ss to ss+nn.
815 memmap=nn[KMG]#ss[KMG]
816 [KNL,ACPI] Mark specific memory as ACPI data.
817 Region of memory to be used, from ss to ss+nn.
819 memmap=nn[KMG]$ss[KMG]
820 [KNL,ACPI] Mark specific memory as reserved.
821 Region of memory to be used, from ss to ss+nn.
823 meye.*= [HW] Set MotionEye Camera parameters
824 See Documentation/video4linux/meye.txt.
829 [MOUSE] Maximum time between finger touching and
830 leaving touchpad surface for touch to be considered
831 a tap and be reported as a left button click (for
832 touchpads working in absolute mode only).
834 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
835 reporting absolute coordinates, such as tablets
836 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
837 reporting absolute coordinates, such as tablets
843 Format: <name>,<region-number>,<size>,<offset>
846 Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
849 See drivers/mtd/cmdline.c.
851 mtouchusb.raw_coordinates=
852 [HW] Make the MicroTouch USB driver use raw coordinates ('y', default)
853 or cooked coordinates ('n')
855 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
858 See header of drivers/scsi/NCR_D700.c.
864 ncr53c400a= [HW,SCSI]
866 ncr53c406a= [HW,SCSI]
870 netdev= [NET] Network devices parameters
871 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
872 Note that mem_start is often overloaded to mean
873 something different and driver-specific.
876 See Documentation/nfsroot.txt.
878 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
879 See Documentation/nfsroot.txt.
881 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
883 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
884 emulation library even if a 387 maths coprocessor
889 noapic [SMP,APIC] Tells the kernel to not make use of any
890 IOAPICs that may be present in the system.
892 noasync [HW,M68K] Disables async and sync negotiation for
895 nobats [PPC] Do not use BATs for mapping kernel lowmem
896 on "Classic" PPC cores.
900 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
904 noexec [IA-32, X86-64]
905 noexec=on: enable non-executable mappings (default)
906 noexec=off: disable nn-executable mappings
912 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
913 instruction doesn't work correctly and not to
916 nohalt [IA-64] Tells the kernel not to use the power saving
917 function PAL_HALT_LIGHT when idle. This increases
918 power-consumption. On the positive side, it reduces
919 interrupt wake-up latency, which may improve performance
920 in certain environments such as networked servers or
923 noirqdebug [IA-32] Disables the code which attempts to detect and
924 disable unhandled interrupt sources.
926 noisapnp [ISAPNP] Disables ISA PnP code.
928 noinitrd [RAM] Tells the kernel not to load any configured
933 nolapic [IA-32,APIC] Do not enable or use the local APIC.
935 noltlbs [PPC] Do not use large page/tlb entries for kernel
936 lowmem mapping on PPC40x.
938 nomce [IA-32] Machine Check Exception
940 noresidual [PPC] Don't use residual data on PReP machines.
942 noresume [SWSUSP] Disables resume and restore original swap space.
944 no-scroll [VGA] Disables scrollback.
945 This is required for the Braillex ib80-piezo Braille
946 reader made by F.H. Papenmeier (Germany).
950 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
952 nosync [HW,M68K] Disables sync negotiation for all devices.
954 notsc [BUGS=IA-32] Disable Time Stamp Counter
956 nousb [USB] Disable the USB subsystem
964 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
967 Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
970 Use timer interrupt instead of performance counters
975 osst= [HW,SCSI] SCSI Tape Driver
976 Format: <buffer_size>,<write_threshold>
977 See also Documentation/scsi/st.txt.
979 panic= [KNL] Kernel behaviour on panic
982 parkbd.port= [HW] Parallel port number the keyboard adapter is
983 connected to, default is 0.
985 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
986 0 for XT, 1 for AT (default is AT).
989 parport=0 [HW,PPT] Specify parallel ports. 0 disables.
990 parport=auto Use 'auto' to force the driver to use
991 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
992 default is to ignore detected IRQ/DMA
993 settings because of possible
994 conflicts). You can specify the base
995 address, IRQ, and DMA settings; IRQ and
996 DMA should be numbers, or 'auto' (for
997 using detected settings on that
998 particular port), or 'nofifo' (to avoid
999 using a FIFO even if it is detected).
1000 Parallel ports are assigned in the
1001 order they are specified on the command
1002 line, starting with parport0.
1005 [HW,PPT] Configure VIA parallel port to
1006 operate in specific mode. This is
1007 necessary on Pegasos computer where
1008 firmware has no options for setting up
1009 parallel port mode and sets it to
1010 spp. Currently this function knows
1011 686a and 8231 chips.
1012 Format: [spp|ps2|epp|ecp|ecpepp]
1015 Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1018 See header of drivers/scsi/pas16.c.
1023 See header of drivers/block/paride/pcd.c.
1024 See also Documentation/paride.txt.
1026 pci=option[,option...] [PCI] various PCI subsystem options:
1027 off [IA-32] don't probe for the PCI bus
1028 bios [IA-32] force use of PCI BIOS, don't access
1029 the hardware directly. Use this if your machine
1030 has a non-standard PCI host bridge.
1031 nobios [IA-32] disallow use of PCI BIOS, only direct
1032 hardware access methods are allowed. Use this
1033 if you experience crashes upon bootup and you
1034 suspect they are caused by the BIOS.
1035 conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
1036 conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
1037 nosort [IA-32] Don't sort PCI devices according to
1038 order given by the PCI BIOS. This sorting is done
1039 to get a device order compatible with older kernels.
1040 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1041 routing table. These calls are known to be buggy
1042 on several machines and they hang the machine when used,
1043 but on other computers it's the only way to get the
1044 interrupt routing table. Try this option if the kernel
1045 is unable to allocate IRQs or discover secondary PCI
1046 buses on your motherboard.
1047 rom [IA-32] Assign address space to expansion ROMs.
1048 Use with caution as certain devices share address
1049 decoders between ROMs and other resources.
1050 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned
1051 automatically to PCI devices. You can make the kernel
1052 exclude IRQs of your ISA cards this way.
1053 pirqaddr=0xAAAAA [IA-32] Specify the physical address
1054 of the PIRQ table (normally generated
1055 by the BIOS) if it is outside the
1056 F0000h-100000h range.
1057 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
1058 if the kernel is unable to find your secondary buses
1059 and you want to tell it explicitly which ones they are.
1060 assign-busses [IA-32] Always assign all PCI bus
1061 numbers ourselves, overriding
1062 whatever the firmware may have
1064 usepirqmask [IA-32] Honor the possible IRQ mask
1065 stored in the BIOS $PIR table. This is
1066 needed on some systems with broken
1067 BIOSes, notably some HP Pavilion N5400
1068 and Omnibook XE3 notebooks. This will
1069 have no effect if ACPI IRQ routing is
1071 noacpi [IA-32] Do not use ACPI for IRQ routing
1072 or for PCI scanning.
1073 routeirq Do IRQ routing for all PCI devices.
1074 This is normally done in pci_enable_device(),
1075 so this option is a temporary workaround
1076 for broken drivers that don't call it.
1078 firmware [ARM] Do not re-enumerate the bus but
1079 instead just use the configuration
1080 from the bootloader. This is currently
1081 used on IXP2000 systems where the
1082 bus has to be configured a certain way
1085 pcmv= [HW,PCMCIA] BadgePAD 4
1088 See Documentation/paride.txt.
1090 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1093 See arch/parisc/kernel/pdc_chassis.c
1096 See Documentation/paride.txt.
1099 See Documentation/paride.txt.
1101 pirq= [SMP,APIC] Manual mp-table setup
1102 See Documentation/i386/IO-APIC.txt.
1104 plip= [PPT,NET] Parallel port network link
1105 Format: { parport<nr> | timid | 0 }
1106 See also Documentation/parport.txt.
1112 { on | off | curr | res | no-curr | no-res }
1115 [ISAPNP] Exclude IRQs for the autoconfiguration
1118 [ISAPNP] Exclude DMAs for the autoconfiguration
1120 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1121 Ranges are in pairs (I/O port base and size).
1124 [ISAPNP] Exclude memory regions for the autoconfiguration
1125 Ranges are in pairs (memory base and size).
1127 profile= [KNL] Enable kernel profiling via /proc/profile
1128 { schedule | <number> }
1129 (param: schedule - profile schedule points}
1130 (param: profile step/bucket size as a power of 2 for
1131 statistical time based profiling)
1133 processor.max_cstate= [HW, ACPI]
1134 Limit processor to maximum C-state
1135 max_cstate=9 overrides any DMI blacklist limit.
1137 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1139 See Documentation/ramdisk.txt.
1141 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1142 probe for (bare|imps|exps|lifebook|any).
1143 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1146 [HW,MOUSE] Try to reset the device after so many bad packets
1149 [HW,MOUSE] Set desired mouse resolution, in dpi.
1150 psmouse.smartscroll=
1151 [HW,MOUSE] Controls Logitech smartscroll autorepeat,
1152 0 = disabled, 1 = enabled (default).
1154 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1155 Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1158 See Documentation/paride.txt.
1160 quiet= [KNL] Disable log messages
1165 See Documentation/md.txt.
1167 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1168 See Documentation/ramdisk.txt.
1172 See Documentation/ramdisk.txt.
1174 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1175 New name for the ramdisk parameter.
1176 See Documentation/ramdisk.txt.
1178 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1179 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1180 See arch/*/kernel/reboot.c.
1182 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1184 resume= [SWSUSP] Specify the partition device for software suspension
1186 rhash_entries= [KNL,NET]
1187 Set number of hash buckets for route cache
1189 riscom8= [HW,SERIAL]
1190 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1192 ro [KNL] Mount root device read-only on boot
1194 root= [KNL] Root filesystem
1196 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1197 mount the root filesystem
1199 rootflags= [KNL] Set root filesystem mount option string
1201 rootfstype= [KNL] Set root filesystem type
1203 rw [KNL] Mount root device read-write on boot
1205 S [KNL] Run init in single mode
1208 See drivers/net/irda/sa1100_ir.c.
1211 Format: <io>,<irq>,<dma>,<dma2>
1213 sbni= [NET] Granch SBNI12 leased line adapter
1215 sbpcd= [HW,CD] Soundblaster CD adapter
1217 See a comment before function sbpcd_setup() in
1218 drivers/cdrom/sbpcd.c.
1220 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1221 Format: <io>[,<timeout>[,<isapnp>]]
1223 scsi_debug_*= [SCSI]
1224 See drivers/scsi/scsi_debug.c.
1226 scsi_default_dev_flags=
1227 [SCSI] SCSI default device flags
1230 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1231 Format: <vendor>:<model>:<flags>
1232 (flags are integer value)
1234 scsi_logging= [SCSI]
1236 selinux [SELINUX] Disable or enable SELinux at boot time.
1237 Format: { "0" | "1" }
1238 See security/selinux/Kconfig help text.
1241 Default value is set via kernel config option.
1242 If enabled at boot time, /selinux/disable can be used
1243 later to disable prior to initial policy load.
1245 serialnumber [BUGS=IA-32]
1247 sg_def_reserved_size=
1251 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1254 Maximal number of shapers.
1257 See header of drivers/scsi/sim710.c.
1263 Format: <io>,<irq>,<dma>
1264 See header of drivers/cdrom/sjcd.c.
1269 Format: <io1>[,<io2>[,...,<io8>]]
1271 snd-ad1816a= [HW,ALSA]
1273 snd-ad1848= [HW,ALSA]
1275 snd-ali5451= [HW,ALSA]
1277 snd-als100= [HW,ALSA]
1279 snd-als4000= [HW,ALSA]
1281 snd-azt2320= [HW,ALSA]
1283 snd-cmi8330= [HW,ALSA]
1285 snd-cmipci= [HW,ALSA]
1287 snd-cs4231= [HW,ALSA]
1289 snd-cs4232= [HW,ALSA]
1291 snd-cs4236= [HW,ALSA]
1293 snd-cs4281= [HW,ALSA]
1295 snd-cs46xx= [HW,ALSA]
1297 snd-dt019x= [HW,ALSA]
1299 snd-dummy= [HW,ALSA]
1301 snd-emu10k1= [HW,ALSA]
1303 snd-ens1370= [HW,ALSA]
1305 snd-ens1371= [HW,ALSA]
1307 snd-es968= [HW,ALSA]
1309 snd-es1688= [HW,ALSA]
1311 snd-es18xx= [HW,ALSA]
1313 snd-es1938= [HW,ALSA]
1315 snd-es1968= [HW,ALSA]
1317 snd-fm801= [HW,ALSA]
1319 snd-gusclassic= [HW,ALSA]
1321 snd-gusextreme= [HW,ALSA]
1323 snd-gusmax= [HW,ALSA]
1327 snd-ice1712= [HW,ALSA]
1329 snd-intel8x0= [HW,ALSA]
1331 snd-interwave= [HW,ALSA]
1336 snd-korg1212= [HW,ALSA]
1338 snd-maestro3= [HW,ALSA]
1340 snd-mpu401= [HW,ALSA]
1342 snd-mtpav= [HW,ALSA]
1344 snd-nm256= [HW,ALSA]
1346 snd-opl3sa2= [HW,ALSA]
1354 snd-opti93x= [HW,ALSA]
1358 snd-rme32= [HW,ALSA]
1360 snd-rme96= [HW,ALSA]
1362 snd-rme9652= [HW,ALSA]
1368 snd-sbawe= [HW,ALSA]
1370 snd-serial= [HW,ALSA]
1372 snd-sgalaxy= [HW,ALSA]
1374 snd-sonicvibes= [HW,ALSA]
1379 snd-sun-cs4231= [HW,ALSA]
1381 snd-trident= [HW,ALSA]
1383 snd-usb-audio= [HW,ALSA,USB]
1385 snd-via82xx= [HW,ALSA]
1387 snd-virmidi= [HW,ALSA]
1389 snd-wavefront= [HW,ALSA]
1391 snd-ymfpci= [HW,ALSA]
1393 sonicvibes= [HW,OSS]
1397 Format: <io>[,<irq>]
1399 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1400 See Documentation/sonypi.txt
1402 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1403 See Documentation/specialix.txt.
1405 spia_io_base= [HW,MTD]
1411 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1413 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1414 See Documentation/scsi/st.txt.
1417 See header of drivers/scsi/seagate.c.
1421 Set the STI (builtin display/keyboard on the HP-PARISC
1422 machines) console (graphic card) which should be used
1423 as the initial boot-console.
1424 See also comment in drivers/video/console/sticore.c.
1427 See comment in drivers/video/console/sticore.c.
1430 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1432 stram_swap= [HW,M68k]
1434 swiotlb= [IA-64] Number of I/O TLB slabs
1438 sym53c416= [HW,SCSI]
1439 See header of drivers/scsi/sym53c416.c.
1442 See header of drivers/scsi/t128.c.
1446 thash_entries= [KNL,NET]
1447 Set number of hash buckets for TCP connection
1449 time Show timing data prefixed to each printk message line
1451 tipar.timeout= [HW,PPT]
1452 Set communications timeout in tenths of a second
1455 tipar.delay= [HW,PPT]
1456 Set inter-bit delay in microseconds (default 10).
1459 See header of drivers/scsi/seagate.c.
1462 See comment before function dc390_setup() in
1463 drivers/scsi/tmscsim.c.
1467 trix= [HW,OSS] MediaTrix AudioTrix Pro
1468 Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1470 tsdev.xres= [TS] Horizontal screen resolution.
1471 tsdev.yres= [TS] Vertical screen resolution.
1473 turbografx.map[2|3]=
1474 [HW,JOY] TurboGraFX parallel port interface
1475 Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1476 See also Documentation/input/joystick-parport.txt
1478 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1479 See header of drivers/scsi/u14-34f.c.
1487 usb-handoff [HW] Enable early USB BIOS -> OS handoff
1490 [USBHID] The interval which mice are to be polled at.
1492 video= [FB] Frame buffer configuration
1493 See Documentation/fb/modedb.txt.
1495 vga= [BOOT,IA-32] Select a particular video mode
1496 See Documentation/i386/boot.txt and Documentation/svga.txt.
1497 Use vga=ask for menu.
1498 This is actually a boot loader parameter; the value is
1499 passed to the kernel using a special protocol.
1501 vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
1502 size of <nn>. This can be used to increase the
1503 minimum size (128MB on x86). It can also be used to
1504 decrease the size and leave more room for directly
1511 waveartist= [HW,OSS]
1512 Format: <io>,<irq>,<dma>,<dma2>
1515 See header of drivers/scsi/wd33c93.c.
1518 See header of drivers/scsi/wd7000.c.
1521 See Documentation/watchdog/watchdog.txt.
1523 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1524 xd_geo= See header of drivers/block/xd.c.
1526 xirc2ps_cs= [NET,PCMCIA]
1527 Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1533 The last known update (for 2.4.0) - the changelog was not kept before.
1534 2000-06-?? Mr. Unknown
1536 Update for 2.5.49, description for most of the options introduced,
1537 references to other documentation (C files, READMEs, ..), added S390,
1538 PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1540 2002-11-24 Petr Baudis <pasky@ucw.cz>
1541 Randy Dunlap <randy.dunlap@verizon.net>
1545 Add documentation for ALSA options.
1546 Add more DRM drivers.