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 DCHP, 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
163 Format: <io>,<irq>,<dma>,<dma2>
164 See also Documentation/sound/oss/AD1816.
167 Format: <io>,<irq>,<dma>,<dma2>,<type>
173 See header of drivers/scsi/advansys.c.
175 advwdt= [HW,WDT] Advantech WDT
176 Format: <iostart>,<iostop>
178 aedsp16= [HW,OSS] Audio Excel DSP 16
179 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
180 See also header of sound/oss/aedsp16.c.
183 See Documentation/scsi/aha152x.txt.
186 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
189 See Documentation/scsi/aic7xxx.txt.
192 See Documentation/scsi/aic79xx.txt.
195 Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
196 See also header of drivers/scsi/AM53C974.c.
198 amijoy.map= [HW,JOY] Amiga joystick support
199 Map of devices attached to JOY0DAT and JOY1DAT
201 See also Documentation/kernel/input/joystick.txt
203 analog.map= [HW,JOY] Analog joystick and gamepad support
204 Specifies type or capabilities of an analog joystick
205 connected to one of 16 gameports
206 Format: <type1>,<type2>,..<type16>
208 apc= [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
210 Disable APC CPU standby support. SPARCstation-Fox does
211 not play well with APC CPU idle - disable it if you have
212 APC and your system crashes randomly.
214 apic= [APIC,i386] Change the output verbosity whilst booting
215 Format: { quiet (default) | verbose | debug }
216 Change the amount of debugging information output
217 when initialising the APIC and IO-APIC components.
219 apm= [APM] Advanced Power Management
220 See header of arch/i386/kernel/apm.c.
225 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
226 Format: <io>,<irq>,<nodeID>
230 atarimouse= [HW,MOUSE] Atari Mouse
232 atascsi= [HW,SCSI] Atari SCSI
234 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
235 EzKey and similar keyboards
237 atkbd.reset= [HW] Reset keyboard during initialization
239 atkbd.set= [HW] Select keyboard code set
240 Format: <int> (2 = AT (default) 3 = PS/2)
242 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
245 atkbd.softraw= [HW] Choose between synthetic and real raw mode
246 Format: <bool> (0 = real, 1 = synthetic (default))
249 [HW] Use software keyboard repeat
253 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
254 Format: <io>,<memsize>,<isapnp>
256 aztcd= [HW,CD] Aztech CD268 CDROM driver
257 Format: <io>,0x79 (?)
259 baycom_epp= [HW,AX25]
262 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
264 See header of drivers/net/hamradio/baycom_par.c.
266 baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
267 Format: <io>,<irq>,<mode>[,<baud>]
268 See header of drivers/net/hamradio/baycom_ser_fdx.c.
270 baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
271 Format: <io>,<irq>,<mode>
272 See header of drivers/net/hamradio/baycom_ser_hdx.c.
274 blkmtd_device= [HW,MTD]
280 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
281 bttv.radio= Most important insmod options are available as kernel args too.
282 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
283 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
286 See drivers/scsi/BusLogic.c, comment before function
287 BusLogic_ParseDriverOptions().
289 c101= [NET] Moxa C101 synchronous serial card
291 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
292 Sometimes CPU hardware bugs make them report the cache
293 size incorrectly. The kernel will attempt work arounds
294 to fix known problems, but for some CPUs it is not
295 possible to determine what the correct size should be.
296 This option provides an override for these situations.
299 Format: <io>,<irq>[,PAS]
300 See header of drivers/cdrom/cdu31a.c.
302 chandev= [HW,NET] Generic channel device initialisation
304 checkreqprot [SELINUX] Set initial checkreqprot flag value.
305 Format: { "0" | "1" }
306 See security/selinux/Kconfig help text.
307 0 -- check protection applied by kernel (includes any implied execute protection).
308 1 -- check protection requested by application.
309 Default value is set via a kernel config option.
310 Value can be changed at runtime via /selinux/checkreqprot.
312 clock= [BUGS=IA-32, HW] gettimeofday timesource override.
313 Forces specified timesource (if avaliable) to be used
314 when calculating gettimeofday(). If specicified timesource
315 is not avalible, it defaults to PIT.
316 Format: { pit | tsc | cyclone | pmtmr }
318 hpet= [IA-32,HPET] option to disable HPET and use PIT.
322 Format: { auto | [<io>,][<irq>] }
324 com20020= [HW,NET] ARCnet - COM20020 chipset
325 Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
327 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
330 com90xx= [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
331 Format: <io>[,<irq>[,<memstart>]]
333 condev= [HW,S390] console device
336 console= [KNL] Output console device and options.
338 tty<n> Use the virtual console device <n>.
341 Use the specified serial port. The options are of
342 the form "bbbbpn", where "bbbb" is the baud rate,
343 "p" is parity ("n", "o", or "e"), and "n" is bits.
346 See also Documentation/serial-console.txt.
348 uart,io,<addr>[,options]
349 uart,mmio,<addr>[,options]
350 Start an early, polled-mode console on the 8250/16550
351 UART at the specified I/O port or MMIO address,
352 switching to the matching ttyS device later. The
353 options are the same as for ttyS, above.
355 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
356 Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
359 Format: { parport<nr> | auto | none }
362 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
367 cs89x0_media= [HW,NET]
368 Format: { rj45 | aui | bnc }
370 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
373 See header of drivers/s390/block/dasd_devmap.c.
375 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
376 (one device per port)
377 Format: <port#>,<type>
378 See also Documentation/input/joystick-parport.txt
380 debug [KNL] Enable kernel debugging (events log level).
383 Format: <area>[,<node>]
384 See also Documentation/networking/decnet.txt.
387 See Documentation/filesystems/devfs/boot-options.
390 Set number of hash buckets for dentry cache.
393 IO parameters + enable/disable command.
395 digiepca= [HW,SERIAL]
396 See drivers/char/README.epca and
397 Documentation/digiepca.txt.
399 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
401 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
403 dmasound= [HW,OSS] Sound subsystem buffers
409 earlyprintk= [IA-32, X86-64]
411 earlyprintk=serial[,ttySn[,baudrate]]
413 Append ,keep to not disable it when the real console
416 Only vga or serial at a time, not both.
418 Currently only ttyS0 and ttyS1 are supported.
420 Interaction with the standard serial driver is not
423 The VGA output is eventually overwritten by the real
433 Format: {"of[f]" | "sk[ipmbr]"}
434 See comment in arch/i386/boot/edd.S
437 Format: <id>,<membase>,<irq>
439 eisa_irq_edge= [PARISC,HW]
440 See header of drivers/parisc/eisa.c.
443 See comment before function elanfreq_setup() in
444 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
447 Format: {"as"|"cfq"|"deadline"|"noop"}
448 See Documentation/block/as-iosched.txt
449 and Documentation/block/deadline-iosched.txt for details.
451 enforcing [SELINUX] Set initial enforcing status.
453 See security/selinux/Kconfig help text.
454 0 -- permissive (log only, no denials).
455 1 -- enforcing (deny and log).
457 Value can be changed at runtime via /selinux/enforce.
460 Format: <lineout>[,<micbias>]
461 See also header of sound/oss/es1370.c.
464 Format: <spdif>,[<nomix>,[<amplifier>]]
465 See also header of sound/oss/es1371.c.
467 ether= [HW,NET] Ethernet cards parameters
468 This option is obsoleted by the "netdev=" option, which
469 has equivalent usage. See its documentation for details.
471 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
475 See header of drivers/scsi/fd_mcs.c.
478 See header of drivers/scsi/fdomain.c.
481 See Documentation/floppy.txt.
483 ftape= [HW] Floppy Tape subsystem debugging options.
484 See Documentation/ftape.txt.
487 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
488 support via parallel port (up to 5 devices per port)
489 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
490 See also Documentation/input/joystick-parport.txt
495 See header of drivers/scsi/gdth.c.
497 gpt [EFI] Forces disk with valid GPT signature but
498 invalid Protective MBR to be treated as GPT.
503 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
506 Format: <io>,<irq>,<dma>,<dma16>
510 hashdist= [KNL,NUMA] Large hashes allocated during boot
511 are distributed across NUMA nodes. Defaults on
512 for IA-64, off otherwise.
514 hcl= [IA-64] SGI's Hardware Graph compatibility layer
516 hd= [EIDE] (E)IDE hard drive subsystem geometry
517 Format: <cyl>,<head>,<sect>
519 hd?= [HW] (E)IDE subsystem
520 hd?lun= See Documentation/ide.txt.
522 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
523 size of <nn>. This works even on boxes that have no
524 highmem otherwise. This also works to reduce highmem
525 size on bigger boxes.
528 See Documentation/isdn/README.HiSax.
530 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
532 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
534 i8042.direct [HW] Put keyboard port into non-translated mode
535 i8042.dumbkbd [HW] Pretend that controlled can only read data from
536 keyboard and can not control its state
537 (Don't attempt to blink the leds)
538 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
539 i8042.nomux [HW] Don't check presence of an active multiplexing
541 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
544 [HW] Frequency with which keyboard LEDs should blink
545 when kernel panics (default is 0.5 sec)
546 i8042.reset [HW] Reset the controller during init and cleanup
547 i8042.unlock [HW] Unlock (ignore) the keylock
551 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
552 indicates that the driver is running on unsupported
554 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
555 does not match list of supported models.
557 [HW] Report power status in /proc/i8k
558 (disabled by default)
559 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
562 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
563 See Documentation/mca.txt.
566 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
568 ide= [HW] (E)IDE subsystem
569 Format: ide=nodma or ide=doubler or ide=reverse
570 See Documentation/ide.txt.
572 ide?= [HW] (E)IDE subsystem
573 Format: ide?=noprobe or chipset specific parameters.
574 See Documentation/ide.txt.
576 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
577 See Documentation/ide.txt.
580 Format: idle=poll or idle=halt
583 Set number of hash buckets for inode cache.
586 See header of drivers/scsi/in2000.c.
590 Run specified binary instead of /sbin/init as init
593 initcall_debug [KNL] Trace initcalls as they are executed. Useful
594 for working out where the kernel is dying during
597 initrd= [BOOT] Specify the location of the initial ramdisk
599 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
604 io7= [HW] IO7 for Marvel based alpha systems
605 See comment before marvel_specify_io7 in
606 arch/alpha/kernel/core_marvel.c.
609 See Documentation/nfsroot.txt.
611 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
612 See comment before ip2_setup() in drivers/char/ip2.c.
614 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
615 See header of drivers/scsi/ips.c.
618 Format: <RDP>, <reset>, <pci_scan>, <verbosity>
620 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
621 Format: <cpu number>,...,<cpu number>
622 This option can be used to specify one or more CPUs
623 to isolate from the general SMP balancing and scheduling
624 algorithms. The only way to move a process onto or off
625 an "isolated" CPU is via the CPU affinity syscalls.
626 <cpu number> begins at 0 and the maximum value is
627 "number of CPUs in system - 1".
629 This option is the preferred way to isolate CPUs. The
630 alternative - manually setting the CPU mask of all tasks
631 in the system can cause problems and suboptimal load
632 balancer performance.
635 Format: <io>,<irq>,<dma>,<setup>
639 js= [HW,JOY] Analog joystick
640 See Documentation/input/joystick.txt.
644 kstack=N [IA-32, X86-64] Print N words from the kernel stack
649 lapic [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
651 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
652 Format: addr:<io>,irq:<irq>
655 See function print_params() in arch/ia64/sn/kernel/llsc4.c.
657 load_ramdisk= [RAM] List of ramdisks to load from floppy
658 See Documentation/ramdisk.txt.
664 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
667 loglevel= All Kernel Messages with a loglevel smaller than the
668 console loglevel will be printed to the console. It can
669 also be changed with klogd or other programs. The
670 loglevels are defined as follows:
672 0 (KERN_EMERG) system is unusable
673 1 (KERN_ALERT) action must be taken immediately
674 2 (KERN_CRIT) critical conditions
675 3 (KERN_ERR) error conditions
676 4 (KERN_WARNING) warning conditions
677 5 (KERN_NOTICE) normal but significant condition
678 6 (KERN_INFO) informational
679 7 (KERN_DEBUG) debug-level messages
681 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
682 Format is n, nk, nM. n must be a power of two. The
683 default is set in kernel config.
685 lp=0 [LP] Specify parallel ports to use, e.g,
686 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
687 lp=reset first parallel port). 'lp=0' disables the
688 lp=auto printer driver. 'lp=reset' (which can be
689 specified in addition to the ports) causes
690 attached printers to be reset. Using
691 lp=port1,port2,... specifies the parallel ports
692 to associate lp devices with, starting with
693 lp0. A port specification may be 'none' to skip
694 that lp device, or a parport name such as
695 'parport0'. Specifying 'lp=auto' instead of a
696 port specification list means that device IDs
697 from each port should be examined, to see if
698 an IEEE 1284-compliant printer is attached; if
699 so, the driver will manage that printer.
700 See also header of drivers/char/lp.c.
703 Sets loops_per_jiffy to given constant, thus avoiding
704 time-consuming boot-time autodetection (up to 250 ms per
705 CPU). 0 enables autodetection (default). To determine
706 the correct value for your kernel, boot with normal
707 autodetection and see what value is printed. Note that
708 on SMP systems the preset will be applied to all CPUs,
709 which is likely to cause problems if your CPUs need
710 significantly divergent settings. An incorrect value
711 will cause delays in the kernel to be wrong, leading to
712 unpredictable I/O errors and other breakage. Although
713 unlikely, in the extreme case this might damage your
717 Format: <io>,<irq>,<dma>
720 Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
723 Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
726 Force the use of a particular machine-vector (machvec) in a generic
727 kernel. Example: machvec=hpzx1_swiotlb
730 Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
735 max_loop= [LOOP] Maximum number of loopback devices that can
739 maxcpus= [SMP] Maximum number of processors that an SMP kernel
742 max_luns= [SCSI] Maximum number of LUNs to probe
743 Should be between 1 and 2^32-1.
746 [SCSI] Maximum number of LUNs received
747 Should be between 1 and 16384.
749 mca-pentium [BUGS=IA-32]
754 Format: <port>,<irq>,<mitsumi_bug_93_wait>
758 mce [IA-32] Machine Check Exception
760 md= [HW] RAID subsystems devices and level
761 See Documentation/md.txt.
764 Format: <first>,<last>
765 Specifies range of consoles to be captured by the MDA.
767 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
768 Amount of memory to be used when the kernel is not able
769 to see the whole system memory or for test.
770 [IA-32] Use together with memmap= to avoid physical
771 address space collisions. Without memmap= PCI devices
772 could be placed at addresses belonging to unused RAM.
774 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
777 memmap=exactmap [KNL,IA-32] Enable setting of an exact
778 E820 memory map, as specified by the user.
779 Such memmap=exactmap lines can be constructed based on
780 BIOS output or other requirements. See the memmap=nn@ss
783 memmap=nn[KMG]@ss[KMG]
784 [KNL] Force usage of a specific region of memory
785 Region of memory to be used, from ss to ss+nn.
787 memmap=nn[KMG]#ss[KMG]
788 [KNL,ACPI] Mark specific memory as ACPI data.
789 Region of memory to be used, from ss to ss+nn.
791 memmap=nn[KMG]$ss[KMG]
792 [KNL,ACPI] Mark specific memory as reserved.
793 Region of memory to be used, from ss to ss+nn.
795 meye.*= [HW] Set MotionEye Camera parameters
796 See Documentation/video4linux/meye.txt.
801 [MOUSE] Maximum time between finger touching and
802 leaving touchpad surface for touch to be considered
803 a tap and be reported as a left button click (for
804 touchpads working in absolute mode only).
806 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
807 reporting absolute coordinates, such as tablets
808 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
809 reporting absolute coordinates, such as tablets
815 Format: <name>,<region-number>,<size>,<offset>
818 Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
821 See drivers/mtd/cmdline.c.
823 mtouchusb.raw_coordinates=
824 [HW] Make the MicroTouch USB driver use raw coordinates ('y', default)
825 or cooked coordinates ('n')
827 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
830 See header of drivers/scsi/NCR_D700.c.
836 ncr53c400a= [HW,SCSI]
838 ncr53c406a= [HW,SCSI]
842 netdev= [NET] Network devices parameters
843 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
844 Note that mem_start is often overloaded to mean
845 something different and driver-specific.
848 See Documentation/nfsroot.txt.
850 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
851 See Documentation/nfsroot.txt.
853 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
855 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
856 emulation library even if a 387 maths coprocessor
861 noapic [SMP,APIC] Tells the kernel to not make use of any
862 IOAPICs that may be present in the system.
864 noasync [HW,M68K] Disables async and sync negotiation for
867 nobats [PPC] Do not use BATs for mapping kernel lowmem
868 on "Classic" PPC cores.
872 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
876 noexec [IA-32, X86-64]
877 noexec=on: enable non-executable mappings (default)
878 noexec=off: disable nn-executable mappings
884 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
885 instruction doesn't work correctly and not to
888 nohalt [IA-64] Tells the kernel not to use the power saving
889 function PAL_HALT_LIGHT when idle. This increases
890 power-consumption. On the positive side, it reduces
891 interrupt wake-up latency, which may improve performance
892 in certain environments such as networked servers or
895 noirqdebug [IA-32] Disables the code which attempts to detect and
896 disable unhandled interrupt sources.
898 noisapnp [ISAPNP] Disables ISA PnP code.
900 noinitrd [RAM] Tells the kernel not to load any configured
905 nolapic [IA-32,APIC] Do not enable or use the local APIC.
907 noltlbs [PPC] Do not use large page/tlb entries for kernel
908 lowmem mapping on PPC40x.
910 nomce [IA-32] Machine Check Exception
912 noresidual [PPC] Don't use residual data on PReP machines.
914 noresume [SWSUSP] Disables resume and restore original swap space.
916 no-scroll [VGA] Disables scrollback.
917 This is required for the Braillex ib80-piezo Braille
918 reader made by F.H. Papenmeier (Germany).
922 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
924 nosync [HW,M68K] Disables sync negotiation for all devices.
926 notsc [BUGS=IA-32] Disable Time Stamp Counter
928 nousb [USB] Disable the USB subsystem
936 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
939 Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
942 Use timer interrupt instead of performance counters
947 osst= [HW,SCSI] SCSI Tape Driver
948 Format: <buffer_size>,<write_threshold>
949 See also Documentation/scsi/st.txt.
951 panic= [KNL] Kernel behaviour on panic
954 parkbd.port= [HW] Parallel port number the keyboard adapter is
955 connected to, default is 0.
957 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
958 0 for XT, 1 for AT (default is AT).
961 parport=0 [HW,PPT] Specify parallel ports. 0 disables.
962 parport=auto Use 'auto' to force the driver to use
963 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
964 default is to ignore detected IRQ/DMA
965 settings because of possible
966 conflicts). You can specify the base
967 address, IRQ, and DMA settings; IRQ and
968 DMA should be numbers, or 'auto' (for
969 using detected settings on that
970 particular port), or 'nofifo' (to avoid
971 using a FIFO even if it is detected).
972 Parallel ports are assigned in the
973 order they are specified on the command
974 line, starting with parport0.
977 [HW,PPT] Configure VIA parallel port to
978 operate in specific mode. This is
979 necessary on Pegasos computer where
980 firmware has no options for setting up
981 parallel port mode and sets it to
982 spp. Currently this function knows
984 Format: [spp|ps2|epp|ecp|ecpepp]
987 Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
990 See header of drivers/scsi/pas16.c.
995 See header of drivers/block/paride/pcd.c.
996 See also Documentation/paride.txt.
998 pci=option[,option...] [PCI] various PCI subsystem options:
999 off [IA-32] don't probe for the PCI bus
1000 bios [IA-32] force use of PCI BIOS, don't access
1001 the hardware directly. Use this if your machine
1002 has a non-standard PCI host bridge.
1003 nobios [IA-32] disallow use of PCI BIOS, only direct
1004 hardware access methods are allowed. Use this
1005 if you experience crashes upon bootup and you
1006 suspect they are caused by the BIOS.
1007 conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
1008 conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
1009 nosort [IA-32] Don't sort PCI devices according to
1010 order given by the PCI BIOS. This sorting is done
1011 to get a device order compatible with older kernels.
1012 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1013 routing table. These calls are known to be buggy
1014 on several machines and they hang the machine when used,
1015 but on other computers it's the only way to get the
1016 interrupt routing table. Try this option if the kernel
1017 is unable to allocate IRQs or discover secondary PCI
1018 buses on your motherboard.
1019 rom [IA-32] Assign address space to expansion ROMs.
1020 Use with caution as certain devices share address
1021 decoders between ROMs and other resources.
1022 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned
1023 automatically to PCI devices. You can make the kernel
1024 exclude IRQs of your ISA cards this way.
1025 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
1026 if the kernel is unable to find your secondary buses
1027 and you want to tell it explicitly which ones they are.
1028 assign-busses [IA-32] Always assign all PCI bus
1029 numbers ourselves, overriding
1030 whatever the firmware may have
1032 usepirqmask [IA-32] Honor the possible IRQ mask
1033 stored in the BIOS $PIR table. This is
1034 needed on some systems with broken
1035 BIOSes, notably some HP Pavilion N5400
1036 and Omnibook XE3 notebooks. This will
1037 have no effect if ACPI IRQ routing is
1039 noacpi [IA-32] Do not use ACPI for IRQ routing
1040 or for PCI scanning.
1041 routeirq Do IRQ routing for all PCI devices.
1042 This is normally done in pci_enable_device(),
1043 so this option is a temporary workaround
1044 for broken drivers that don't call it.
1046 firmware [ARM] Do not re-enumerate the bus but
1047 instead just use the configuration
1048 from the bootloader. This is currently
1049 used on IXP2000 systems where the
1050 bus has to be configured a certain way
1053 pcmv= [HW,PCMCIA] BadgePAD 4
1056 See Documentation/paride.txt.
1058 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1061 See arch/parisc/kernel/pdc_chassis.c
1064 See Documentation/paride.txt.
1067 See Documentation/paride.txt.
1069 pirq= [SMP,APIC] Manual mp-table setup
1070 See Documentation/i386/IO-APIC.txt.
1072 plip= [PPT,NET] Parallel port network link
1073 Format: { parport<nr> | timid | 0 }
1074 See also Documentation/parport.txt.
1080 { on | off | curr | res | no-curr | no-res }
1083 [ISAPNP] Exclude IRQs for the autoconfiguration
1086 [ISAPNP] Exclude DMAs for the autoconfiguration
1088 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1089 Ranges are in pairs (I/O port base and size).
1092 [ISAPNP] Exclude memory regions for the autoconfiguration
1093 Ranges are in pairs (memory base and size).
1095 profile= [KNL] Enable kernel profiling via /proc/profile
1096 { schedule | <number> }
1097 (param: schedule - profile schedule points}
1098 (param: profile step/bucket size as a power of 2 for
1099 statistical time based profiling)
1101 processor.max_cstate= [HW, ACPI]
1102 Limit processor to maximum C-state
1103 max_cstate=9 overrides any DMI blacklist limit.
1105 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1107 See Documentation/ramdisk.txt.
1109 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1110 probe for (bare|imps|exps).
1111 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1114 [HW,MOUSE] Try to reset the device after so many bad packets
1117 [HW,MOUSE] Set desired mouse resolution, in dpi.
1118 psmouse.smartscroll=
1119 [HW,MOUSE] Controls Logitech smartscroll autorepeat,
1120 0 = disabled, 1 = enabled (default).
1122 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1123 Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1126 See Documentation/paride.txt.
1128 quiet= [KNL] Disable log messages
1133 See Documentation/md.txt.
1135 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1136 See Documentation/ramdisk.txt.
1140 See Documentation/ramdisk.txt.
1142 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1143 New name for the ramdisk parameter.
1144 See Documentation/ramdisk.txt.
1146 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1147 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1148 See arch/*/kernel/reboot.c.
1150 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1152 resume= [SWSUSP] Specify the partition device for software suspension
1154 rhash_entries= [KNL,NET]
1155 Set number of hash buckets for route cache
1157 riscom8= [HW,SERIAL]
1158 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1160 ro [KNL] Mount root device read-only on boot
1162 root= [KNL] Root filesystem
1164 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1165 mount the root filesystem
1167 rootflags= [KNL] Set root filesystem mount option string
1169 rootfstype= [KNL] Set root filesystem type
1171 rw [KNL] Mount root device read-write on boot
1173 S [KNL] Run init in single mode
1176 See drivers/net/irda/sa1100_ir.c.
1179 Format: <io>,<irq>,<dma>,<dma2>
1181 sbni= [NET] Granch SBNI12 leased line adapter
1183 sbpcd= [HW,CD] Soundblaster CD adapter
1185 See a comment before function sbpcd_setup() in
1186 drivers/cdrom/sbpcd.c.
1188 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1189 Format: <io>[,<timeout>[,<isapnp>]]
1191 scsi_debug_*= [SCSI]
1192 See drivers/scsi/scsi_debug.c.
1194 scsi_default_dev_flags=
1195 [SCSI] SCSI default device flags
1198 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1199 Format: <vendor>:<model>:<flags>
1200 (flags are integer value)
1202 scsi_logging= [SCSI]
1204 selinux [SELINUX] Disable or enable SELinux at boot time.
1205 Format: { "0" | "1" }
1206 See security/selinux/Kconfig help text.
1209 Default value is set via kernel config option.
1210 If enabled at boot time, /selinux/disable can be used
1211 later to disable prior to initial policy load.
1213 serialnumber [BUGS=IA-32]
1215 sg_def_reserved_size=
1219 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1222 Maximal number of shapers.
1225 See header of drivers/scsi/sim710.c.
1231 Format: <io>,<irq>,<dma>
1232 See header of drivers/cdrom/sjcd.c.
1237 Format: <io1>[,<io2>[,...,<io8>]]
1239 snd-ad1816a= [HW,ALSA]
1241 snd-ad1848= [HW,ALSA]
1243 snd-ali5451= [HW,ALSA]
1245 snd-als100= [HW,ALSA]
1247 snd-als4000= [HW,ALSA]
1249 snd-azt2320= [HW,ALSA]
1251 snd-cmi8330= [HW,ALSA]
1253 snd-cmipci= [HW,ALSA]
1255 snd-cs4231= [HW,ALSA]
1257 snd-cs4232= [HW,ALSA]
1259 snd-cs4236= [HW,ALSA]
1261 snd-cs4281= [HW,ALSA]
1263 snd-cs46xx= [HW,ALSA]
1265 snd-dt019x= [HW,ALSA]
1267 snd-dummy= [HW,ALSA]
1269 snd-emu10k1= [HW,ALSA]
1271 snd-ens1370= [HW,ALSA]
1273 snd-ens1371= [HW,ALSA]
1275 snd-es968= [HW,ALSA]
1277 snd-es1688= [HW,ALSA]
1279 snd-es18xx= [HW,ALSA]
1281 snd-es1938= [HW,ALSA]
1283 snd-es1968= [HW,ALSA]
1285 snd-fm801= [HW,ALSA]
1287 snd-gusclassic= [HW,ALSA]
1289 snd-gusextreme= [HW,ALSA]
1291 snd-gusmax= [HW,ALSA]
1295 snd-ice1712= [HW,ALSA]
1297 snd-intel8x0= [HW,ALSA]
1299 snd-interwave= [HW,ALSA]
1304 snd-korg1212= [HW,ALSA]
1306 snd-maestro3= [HW,ALSA]
1308 snd-mpu401= [HW,ALSA]
1310 snd-mtpav= [HW,ALSA]
1312 snd-nm256= [HW,ALSA]
1314 snd-opl3sa2= [HW,ALSA]
1322 snd-opti93x= [HW,ALSA]
1326 snd-rme32= [HW,ALSA]
1328 snd-rme96= [HW,ALSA]
1330 snd-rme9652= [HW,ALSA]
1336 snd-sbawe= [HW,ALSA]
1338 snd-serial= [HW,ALSA]
1340 snd-sgalaxy= [HW,ALSA]
1342 snd-sonicvibes= [HW,ALSA]
1347 snd-sun-cs4231= [HW,ALSA]
1349 snd-trident= [HW,ALSA]
1351 snd-usb-audio= [HW,ALSA,USB]
1353 snd-via82xx= [HW,ALSA]
1355 snd-virmidi= [HW,ALSA]
1357 snd-wavefront= [HW,ALSA]
1359 snd-ymfpci= [HW,ALSA]
1361 sonicvibes= [HW,OSS]
1365 Format: <io>[,<irq>]
1367 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1368 See Documentation/sonypi.txt
1370 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1371 See Documentation/specialix.txt.
1373 spia_io_base= [HW,MTD]
1379 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1381 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1382 See Documentation/scsi/st.txt.
1385 See header of drivers/scsi/seagate.c.
1389 Set the STI (builtin display/keyboard on the HP-PARISC
1390 machines) console (graphic card) which should be used
1391 as the initial boot-console.
1392 See also comment in drivers/video/console/sticore.c.
1395 See comment in drivers/video/console/sticore.c.
1398 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1400 stram_swap= [HW,M68k]
1402 swiotlb= [IA-64] Number of I/O TLB slabs
1406 sym53c416= [HW,SCSI]
1407 See header of drivers/scsi/sym53c416.c.
1410 See header of drivers/scsi/t128.c.
1414 thash_entries= [KNL,NET]
1415 Set number of hash buckets for TCP connection
1417 time Show timing data prefixed to each printk message line
1419 tipar.timeout= [HW,PPT]
1420 Set communications timeout in tenths of a second
1423 tipar.delay= [HW,PPT]
1424 Set inter-bit delay in microseconds (default 10).
1427 See header of drivers/scsi/seagate.c.
1430 See comment before function dc390_setup() in
1431 drivers/scsi/tmscsim.c.
1435 trix= [HW,OSS] MediaTrix AudioTrix Pro
1436 Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1438 tsdev.xres= [TS] Horizontal screen resolution.
1439 tsdev.yres= [TS] Vertical screen resolution.
1441 turbografx.map[2|3]=
1442 [HW,JOY] TurboGraFX parallel port interface
1443 Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1444 See also Documentation/input/joystick-parport.txt
1446 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1447 See header of drivers/scsi/u14-34f.c.
1455 usb-handoff [HW] Enable early USB BIOS -> OS handoff
1458 [USBHID] The interval which mice are to be polled at.
1460 video= [FB] Frame buffer configuration
1461 See Documentation/fb/modedb.txt.
1463 vga= [BOOT,IA-32] Select a particular video mode
1464 See Documentation/i386/boot.txt and Documentation/svga.txt.
1465 Use vga=ask for menu.
1466 This is actually a boot loader parameter; the value is
1467 passed to the kernel using a special protocol.
1469 vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
1470 size of <nn>. This can be used to increase the
1471 minimum size (128MB on x86). It can also be used to
1472 decrease the size and leave more room for directly
1479 waveartist= [HW,OSS]
1480 Format: <io>,<irq>,<dma>,<dma2>
1483 See header of drivers/scsi/wd33c93.c.
1486 See header of drivers/scsi/wd7000.c.
1489 See Documentation/watchdog/watchdog.txt.
1491 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1492 xd_geo= See header of drivers/block/xd.c.
1494 xirc2ps_cs= [NET,PCMCIA]
1495 Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1501 The last known update (for 2.4.0) - the changelog was not kept before.
1502 2000-06-?? Mr. Unknown
1504 Update for 2.5.49, description for most of the options introduced,
1505 references to other documentation (C files, READMEs, ..), added S390,
1506 PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1508 2002-11-24 Petr Baudis <pasky@ucw.cz>
1509 Randy Dunlap <randy.dunlap@verizon.net>
1513 Add documentation for ALSA options.
1514 Add more DRM drivers.