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 NFS Appropriate NFS support is enabled.
55 OSS OSS sound support is enabled.
56 PARIDE The ParIDE subsystem is enabled.
57 PARISC The PA-RISC architecture is enabled.
58 PCI PCI bus support is enabled.
59 PCMCIA The PCMCIA subsystem is enabled.
60 PNP Plug & Play support is enabled.
61 PPC PowerPC architecture is enabled.
62 PPT Parallel port support is enabled.
63 PS2 Appropriate PS/2 support is enabled.
64 RAM RAM disk support is enabled.
65 S390 S390 architecture is enabled.
66 SCSI Appropriate SCSI support is enabled.
67 A lot of drivers has their options described inside of
69 SERIAL Serial support is enabled.
70 SMP The kernel is an SMP kernel.
71 SPARC Sparc architecture is enabled.
72 SWSUSP Software suspension is enabled.
73 TS Appropriate touchscreen support is enabled.
74 USB USB support is enabled.
75 V4L Video For Linux support is enabled.
76 VGA The VGA console has been enabled.
77 VT Virtual terminal support is enabled.
78 WDT Watchdog support is enabled.
79 XT IBM PC/XT MFM hard disk support is enabled.
81 In addition, the following text indicates that the option:
83 BUGS= Relates to possible processor bugs on the said processor.
84 KNL Is a kernel start-up parameter.
85 BOOT Is a boot loader parameter.
87 Parameters denoted with BOOT are actually interpreted by the boot
88 loader, and have no meaning to the kernel directly.
89 Do not modify the syntax of boot loader parameters without extreme
90 need or coordination with <Documentation/i386/boot.txt>.
92 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
93 a trailing = on the name of any parameter states that that parameter will
94 be entered as an environment variable, whereas its absence indicates that
95 it will appear as a kernel argument readable via /proc/cmdline by programs
96 running once the system is up.
98 53c7xx= [HW,SCSI] Amiga SCSI controllers
99 See header of drivers/scsi/53c7xx.c.
100 See also Documentation/scsi/ncr53c7xx.txt.
102 acpi= [HW,ACPI] Advanced Configuration and Power Interface
103 Format: { force | off | ht | strict }
104 force -- enable ACPI if default was off
105 off -- disable ACPI if default was on
106 noirq -- do not use ACPI for IRQ routing
107 ht -- run only enough ACPI to enable Hyper Threading
108 strict -- Be less tolerant of platforms that are not
109 strictly ACPI specification compliant.
111 See also Documentation/pm.txt, pci=noacpi
113 acpi_sleep= [HW,ACPI] Sleep options
114 Format: { s3_bios, s3_mode }
115 See Documentation/power/video.txt
117 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
118 Format: { level | edge | high | low }
120 acpi_irq_balance [HW,ACPI] ACPI will balance active IRQs
123 acpi_irq_nobalance [HW,ACPI] ACPI will not move active IRQs (default)
126 acpi_irq_pci= [HW,ACPI] If irq_balance, Clear listed IRQs for use by PCI
127 Format: <irq>,<irq>...
129 acpi_irq_isa= [HW,ACPI] If irq_balance, Mark listed IRQs used by ISA
130 Format: <irq>,<irq>...
132 acpi_osi= [HW,ACPI] empty param disables _OSI
134 acpi_serialize [HW,ACPI] force serialization of AML methods
136 acpi_skip_timer_override [HW,ACPI]
137 Recognize and ignore IRQ0/pin2 Interrupt Override.
138 For broken nForce2 BIOS resulting in XT-PIC timer.
140 acpi_dbg_layer= [HW,ACPI]
142 Each bit of the <int> indicates an acpi debug layer,
143 1: enable, 0: disable. It is useful for boot time
144 debugging. After system has booted up, it can be set
145 via /proc/acpi/debug_layer.
147 acpi_dbg_level= [HW,ACPI]
149 Each bit of the <int> indicates an acpi debug level,
150 1: enable, 0: disable. It is useful for boot time
151 debugging. After system has booted up, it can be set
152 via /proc/acpi/debug_level.
155 Format: <io>,<irq>,<dma>,<dma2>
156 See also Documentation/sound/oss/AD1816.
159 Format: <io>,<irq>,<dma>,<dma2>,<type>
165 See header of drivers/scsi/advansys.c.
167 advwdt= [HW,WDT] Advantech WDT
168 Format: <iostart>,<iostop>
170 aedsp16= [HW,OSS] Audio Excel DSP 16
171 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
172 See also header of sound/oss/aedsp16.c.
175 See Documentation/scsi/aha152x.txt.
178 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
181 See Documentation/scsi/aic7xxx.txt.
184 See Documentation/scsi/aic79xx.txt.
187 Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
188 See also header of drivers/scsi/AM53C974.c.
190 amijoy.map= [HW,JOY] Amiga joystick support
191 Map of devices attached to JOY0DAT and JOY1DAT
193 See also Documentation/kernel/input/joystick.txt
195 analog.map= [HW,JOY] Analog joystick and gamepad support
196 Specifies type or capabilities of an analog joystick
197 connected to one of 16 gameports
198 Format: <type1>,<type2>,..<type16>
200 apc= [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
202 Disable APC CPU standby support. SPARCstation-Fox does
203 not play well with APC CPU idle - disable it if you have
204 APC and your system crashes randomly.
206 apic= [APIC,i386] Change the output verbosity whilst booting
207 Format: { quiet (default) | verbose | debug }
208 Change the amount of debugging information output
209 when initialising the APIC and IO-APIC components.
211 apm= [APM] Advanced Power Management
212 See header of arch/i386/kernel/apm.c.
217 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
218 Format: <io>,<irq>,<nodeID>
222 atarimouse= [HW,MOUSE] Atari Mouse
224 atascsi= [HW,SCSI] Atari SCSI
226 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, EzKey
227 and similar keyboards
229 atkbd.reset= [HW] Reset keyboard during initialization
231 atkbd.set= [HW] Select keyboard code set
232 Format: <int> (2 = AT (default) 3 = PS/2)
234 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar keyboards
237 [HW] Use software keyboard repeat
241 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
242 Format: <io>,<memsize>,<isapnp>
244 aztcd= [HW,CD] Aztech CD268 CDROM driver
245 Format: <io>,0x79 (?)
247 baycom_epp= [HW,AX25]
250 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
252 See header of drivers/net/hamradio/baycom_par.c.
254 baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
255 Format: <io>,<irq>,<mode>[,<baud>]
256 See header of drivers/net/hamradio/baycom_ser_fdx.c.
258 baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
259 Format: <io>,<irq>,<mode>
260 See header of drivers/net/hamradio/baycom_ser_hdx.c.
262 blkmtd_device= [HW,MTD]
268 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
269 bttv.radio= Most important insmod options are available as kernel args too.
270 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
271 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
274 See drivers/scsi/BusLogic.c, comment before function
275 BusLogic_ParseDriverOptions().
277 c101= [NET] Moxa C101 synchronous serial card
279 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
280 Sometimes CPU hardware bugs make them report the cache
281 size incorrectly. The kernel will attempt work arounds
282 to fix known problems, but for some CPUs it is not
283 possible to determine what the correct size should be.
284 This option provides an override for these situations.
287 Format: <io>,<irq>[,PAS]
288 See header of drivers/cdrom/cdu31a.c.
290 chandev= [HW,NET] Generic channel device initialisation
292 clock= [BUGS=IA-32, HW] gettimeofday timesource override.
293 Forces specified timesource (if avaliable) to be used
294 when calculating gettimeofday(). If specicified timesource
295 is not avalible, it defaults to PIT.
296 Format: { pit | tsc | cyclone | pmtmr }
298 hpet= [IA-32,HPET] option to disable HPET and use PIT.
302 Format: { auto | [<io>,][<irq>] }
304 com20020= [HW,NET] ARCnet - COM20020 chipset
305 Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
307 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
310 com90xx= [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
311 Format: <io>[,<irq>[,<memstart>]]
313 condev= [HW,S390] console device
316 console= [KNL] Output console device and options.
318 tty<n> Use the virtual console device <n>.
321 Use the specified serial port. The options are of
322 the form "bbbbpn", where "bbbb" is the baud rate,
323 "p" is parity ("n", "o", or "e"), and "n" is bits.
326 See also Documentation/serial-console.txt.
328 uart,io,<addr>[,options]
329 uart,mmio,<addr>[,options]
330 Start an early, polled-mode console on the 8250/16550
331 UART at the specified I/O port or MMIO address,
332 switching to the matching ttyS device later. The
333 options are the same as for ttyS, above.
335 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
336 Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
339 Format: { parport<nr> | auto | none }
342 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
347 cs89x0_media= [HW,NET]
348 Format: { rj45 | aui | bnc }
350 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
353 See header of drivers/s390/block/dasd_devmap.c.
355 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
356 (one device per port)
357 Format: <port#>,<type>
358 See also Documentation/input/joystick-parport.txt
360 debug [KNL] Enable kernel debugging (events log level).
363 Format: <area>[,<node>]
364 See also Documentation/networking/decnet.txt.
367 See Documentation/filesystems/devfs/boot-options.
370 Set number of hash buckets for dentry cache.
373 IO parameters + enable/disable command.
375 digiepca= [HW,SERIAL]
376 See drivers/char/README.epca and
377 Documentation/digiepca.txt.
379 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
381 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
383 dmasound= [HW,OSS] Sound subsystem buffers
389 earlyprintk= [x86, x86_64]
391 earlyprintk=serial[,ttySn[,baudrate]]
393 Append ,keep to not disable it when the real console
396 Only vga or serial at a time, not both.
398 Currently only ttyS0 and ttyS1 are supported.
400 Interaction with the standard serial driver is not
403 The VGA output is eventually overwritten by the real
413 Format: {"of[f]" | "sk[ipmbr]"}
414 See comment in arch/i386/boot/edd.S
417 Format: <id>,<membase>,<irq>
419 eisa_irq_edge= [PARISC,HW]
420 See header of drivers/parisc/eisa.c.
423 See comment before function elanfreq_setup() in
424 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
427 Format: {"as"|"cfq"|"deadline"|"noop"}
428 See Documentation/block/as-iosched.txt
429 and Documentation/block/deadline-iosched.txt for details.
432 Format: <lineout>[,<micbias>]
433 See also header of sound/oss/es1370.c.
436 Format: <spdif>,[<nomix>,[<amplifier>]]
437 See also header of sound/oss/es1371.c.
439 ether= [HW,NET] Ethernet cards parameters
440 This option is obsoleted by the "netdev=" option, which
441 has equivalent usage. See its documentation for details.
443 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
447 See header of drivers/scsi/fd_mcs.c.
450 See header of drivers/scsi/fdomain.c.
453 See Documentation/floppy.txt.
455 ftape= [HW] Floppy Tape subsystem debugging options.
456 See Documentation/ftape.txt.
459 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
460 support via parallel port (up to 5 devices per port)
461 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
462 See also Documentation/input/joystick-parport.txt
467 See header of drivers/scsi/gdth.c.
469 gpt [EFI] Forces disk with valid GPT signature but
470 invalid Protective MBR to be treated as GPT.
475 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
478 Format: <io>,<irq>,<dma>,<dma16>
482 hcl= [IA-64] SGI's Hardware Graph compatibility layer
484 hd= [EIDE] (E)IDE hard drive subsystem geometry
485 Format: <cyl>,<head>,<sect>
487 hd?= [HW] (E)IDE subsystem
488 hd?lun= See Documentation/ide.txt.
490 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
491 size of <nn>. This works even on boxes that have no
492 highmem otherwise. This also works to reduce highmem
493 size on bigger boxes.
496 See Documentation/isdn/README.HiSax.
498 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
500 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
502 i8042.direct [HW] Put keyboard port into non-translated mode
503 i8042.dumbkbd [HW] Pretend that controlled can only read data from
504 keyboard and can not control its state
505 (Don't attempt to blink the leds)
506 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
507 i8042.nomux [HW] Don't check presence of an active multiplexing
509 i8042.reset [HW] Reset the controller during init and cleanup
510 i8042.unlock [HW] Unlock (ignore) the keylock
514 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
515 does not match list of supported models.
517 [HW] Report power status in /proc/i8k
518 (disabled by default)
519 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
522 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
523 See Documentation/mca.txt.
526 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
528 ide= [HW] (E)IDE subsystem
529 Format: ide=nodma or ide=doubler or ide=reverse
530 See Documentation/ide.txt.
532 ide?= [HW] (E)IDE subsystem
533 Format: ide?=noprobe or chipset specific parameters.
534 See Documentation/ide.txt.
536 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
537 See Documentation/ide.txt.
540 Format: idle=poll or idle=halt
543 Set number of hash buckets for inode cache.
546 See header of drivers/scsi/in2000.c.
550 Run specified binary instead of /sbin/init as init
553 initcall_debug [KNL] Trace initcalls as they are executed. Useful
554 for working out where the kernel is dying during
557 initrd= [BOOT] Specify the location of the initial ramdisk
559 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
564 io7= [HW] IO7 for Marvel based alpha systems
565 See comment before marvel_specify_io7 in
566 arch/alpha/kernel/core_marvel.c.
569 See Documentation/nfsroot.txt.
571 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
572 See comment before ip2_setup() in drivers/char/ip2.c.
574 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
575 See header of drivers/scsi/ips.c.
578 When an interrupt is not handled search all handlers
579 for it. Intended to get systems with badly broken
583 When an interrupt is not handled search all handlers
584 for it. Also check all handlers each timer
585 interrupt. Intended to get systems with badly broken
589 Format: <RDP>, <reset>, <pci_scan>, <verbosity>
591 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
592 Format: <cpu number>, ..., <cpu number>
593 This option can be used to specify one or more CPUs
594 to isolate from the general SMP balancing and scheduling
595 algorithms. The only way to move a process onto or off
596 an "isolated" CPU is via the CPU affinity syscalls.
598 This option is the preferred way to isolate CPUs. The
599 alternative - manually setting the CPU mask of all tasks
600 in the system can cause problems and suboptimal load
601 balancer performance.
604 Format: <io>,<irq>,<dma>,<setup>
608 js= [HW,JOY] Analog joystick
609 See Documentation/input/joystick.txt.
615 lapic [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
617 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
618 Format: addr:<io>,irq:<irq>
621 See function print_params() in arch/ia64/sn/kernel/llsc4.c.
623 load_ramdisk= [RAM] List of ramdisks to load from floppy
624 See Documentation/ramdisk.txt.
630 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
633 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
634 Format is n, nk, nM. n must be a power of two. The
635 default is set in kernel config.
637 lp=0 [LP] Specify parallel ports to use, e.g,
638 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
639 lp=reset first parallel port). 'lp=0' disables the
640 lp=auto printer driver. 'lp=reset' (which can be
641 specified in addition to the ports) causes
642 attached printers to be reset. Using
643 lp=port1,port2,... specifies the parallel ports
644 to associate lp devices with, starting with
645 lp0. A port specification may be 'none' to skip
646 that lp device, or a parport name such as
647 'parport0'. Specifying 'lp=auto' instead of a
648 port specification list means that device IDs
649 from each port should be examined, to see if
650 an IEEE 1284-compliant printer is attached; if
651 so, the driver will manage that printer.
652 See also header of drivers/char/lp.c.
655 Sets loops_per_jiffy to given constant, thus avoiding
656 time-consuming boot-time autodetection (up to 250 ms per
657 CPU). 0 enables autodetection (default). To determine
658 the correct value for your kernel, boot with normal
659 autodetection and see what value is printed. Note that
660 on SMP systems the preset will be applied to all CPUs,
661 which is likely to cause problems if your CPUs need
662 significantly divergent settings. An incorrect value
663 will cause delays in the kernel to be wrong, leading to
664 unpredictable I/O errors and other breakage. Although
665 unlikely, in the extreme case this might damage your
669 Format: <io>,<irq>,<dma>
672 Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
675 Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
678 Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
683 max_loop= [LOOP] Maximum number of loopback devices that can
687 maxcpus= [SMP] Maximum number of processors that an SMP kernel
690 max_luns= [SCSI] Maximum number of LUNs to probe
691 Should be between 1 and 2^32-1.
694 [SCSI] Maximum number of LUNs received
695 Should be between 1 and 16384.
697 mca-pentium [BUGS=IA-32]
702 Format: <port>,<irq>,<mitsumi_bug_93_wait>
706 mce [IA-32] Machine Check Exception
708 md= [HW] RAID subsystems devices and level
709 See Documentation/md.txt.
712 Format: <first>,<last>
713 Specifies range of consoles to be captured by the MDA.
715 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
716 Amount of memory to be used when the kernel is not able
717 to see the whole system memory or for test.
718 [IA-32] Use together with memmap= to avoid physical
719 address space collisions. Without memmap= PCI devices
720 could be placed at addresses belonging to unused RAM.
722 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
725 memmap=exactmap [KNL,IA-32] Enable setting of an exact
726 E820 memory map, as specified by the user.
727 Such memmap=exactmap lines can be constructed based on
728 BIOS output or other requirements. See the memmap=nn@ss
731 memmap=nn[KMG]@ss[KMG]
732 [KNL] Force usage of a specific region of memory
733 Region of memory to be used, from ss to ss+nn.
735 memmap=nn[KMG]#ss[KMG]
736 [KNL,ACPI] Mark specific memory as ACPI data.
737 Region of memory to be used, from ss to ss+nn.
739 memmap=nn[KMG]$ss[KMG]
740 [KNL,ACPI] Mark specific memory as reserved.
741 Region of memory to be used, from ss to ss+nn.
743 meye.*= [HW] Set MotionEye Camera parameters
744 See Documentation/video4linux/meye.txt.
749 [MOUSE] Maximum time between finger touching and
750 leaving touchpad surface for touch to be considered
751 a tap and be reported as a left button click (for
752 touchpads working in absolute mode only).
754 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
755 reporting absolute coordinates, such as tablets
756 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
757 reporting absolute coordinates, such as tablets
763 Format: <name>,<region-number>,<size>,<offset>
766 Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
769 See drivers/mtd/cmdline.c.
771 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
774 See header of drivers/scsi/NCR_D700.c.
780 ncr53c400a= [HW,SCSI]
782 ncr53c406a= [HW,SCSI]
786 netdev= [NET] Network devices parameters
787 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
788 Note that mem_start is often overloaded to mean
789 something different and driver-specific.
792 See Documentation/nfsroot.txt.
794 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
795 See Documentation/nfsroot.txt.
797 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
799 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
800 emulation library even if a 387 maths coprocessor
805 noapic [SMP,APIC] Tells the kernel to not make use of any
806 IOAPICs that may be present in the system.
808 noasync [HW,M68K] Disables async and sync negotiation for
811 nobats [PPC] Do not use BATs for mapping kernel lowmem
812 on "Classic" PPC cores.
816 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
820 noexec [i386, x86_64]
821 noexec=on: enable non-executable mappings (default)
822 noexec=off: disable nn-executable mappings
828 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
829 instruction doesn't work correctly and not to
832 noirqdebug [IA-32] Disables the code which attempts to detect and
833 disable unhandled interrupt sources.
835 noisapnp [ISAPNP] Disables ISA PnP code.
837 noinitrd [RAM] Tells the kernel not to load any configured
842 nolapic [IA-32,APIC] Do not enable or use the local APIC.
844 noltlbs [PPC] Do not use large page/tlb entries for kernel
845 lowmem mapping on PPC40x.
847 nomce [IA-32] Machine Check Exception
849 noresidual [PPC] Don't use residual data on PReP machines.
851 noresume [SWSUSP] Disables resume and restore original swap space.
853 no-scroll [VGA] Disables scrollback.
854 This is required for the Braillex ib80-piezo Braille
855 reader made by F.H. Papenmeier (Germany).
859 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
861 nosync [HW,M68K] Disables sync negotiation for all devices.
863 notsc [BUGS=IA-32] Disable Time Stamp Counter
865 nousb [USB] Disable the USB subsystem
873 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
876 Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
879 Use timer interrupt instead of performance counters
884 osst= [HW,SCSI] SCSI Tape Driver
885 Format: <buffer_size>,<write_threshold>
886 See also Documentation/scsi/st.txt.
888 panic= [KNL] Kernel behaviour on panic
891 parport=0 [HW,PPT] Specify parallel ports. 0 disables.
892 parport=auto Use 'auto' to force the driver to use
893 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
894 default is to ignore detected IRQ/DMA
895 settings because of possible
896 conflicts). You can specify the base
897 address, IRQ, and DMA settings; IRQ and
898 DMA should be numbers, or 'auto' (for
899 using detected settings on that
900 particular port), or 'nofifo' (to avoid
901 using a FIFO even if it is detected).
902 Parallel ports are assigned in the
903 order they are specified on the command
904 line, starting with parport0.
907 [HW,PPT] Configure VIA parallel port to
908 operate in specific mode. This is
909 necessary on Pegasos computer where
910 firmware has no options for setting up
911 parallel port mode and sets it to
912 spp. Currently this function knows
914 Format: [spp|ps2|epp|ecp|ecpepp]
917 Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
920 See header of drivers/scsi/pas16.c.
925 See header of drivers/block/paride/pcd.c.
926 See also Documentation/paride.txt.
928 pci=option[,option...] [PCI] various PCI subsystem options:
929 off [IA-32] don't probe for the PCI bus
930 bios [IA-32] force use of PCI BIOS, don't access
931 the hardware directly. Use this if your machine
932 has a non-standard PCI host bridge.
933 nobios [IA-32] disallow use of PCI BIOS, only direct
934 hardware access methods are allowed. Use this
935 if you experience crashes upon bootup and you
936 suspect they are caused by the BIOS.
937 conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
938 conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
939 nosort [IA-32] Don't sort PCI devices according to
940 order given by the PCI BIOS. This sorting is done
941 to get a device order compatible with older kernels.
942 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
943 routing table. These calls are known to be buggy
944 on several machines and they hang the machine when used,
945 but on other computers it's the only way to get the
946 interrupt routing table. Try this option if the kernel
947 is unable to allocate IRQs or discover secondary PCI
948 buses on your motherboard.
949 rom [IA-32] Assign address space to expansion ROMs.
950 Use with caution as certain devices share address
951 decoders between ROMs and other resources.
952 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned
953 automatically to PCI devices. You can make the kernel
954 exclude IRQs of your ISA cards this way.
955 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
956 if the kernel is unable to find your secondary buses
957 and you want to tell it explicitly which ones they are.
958 assign-busses [IA-32] Always assign all PCI bus
959 numbers ourselves, overriding
960 whatever the firmware may have
962 usepirqmask [IA-32] Honor the possible IRQ mask
963 stored in the BIOS $PIR table. This is
964 needed on some systems with broken
965 BIOSes, notably some HP Pavilion N5400
966 and Omnibook XE3 notebooks. This will
967 have no effect if ACPI IRQ routing is
969 noacpi [IA-32] Do not use ACPI for IRQ routing
971 routeirq Do IRQ routing for all PCI devices.
972 This is normally done in pci_enable_device(),
973 so this option is a temporary workaround
974 for broken drivers that don't call it.
976 firmware [ARM] Do not re-enumerate the bus but
977 instead just use the configuration
978 from the bootloader. This is currently
979 used on IXP2000 systems where the
980 bus has to be configured a certain way
983 pcmv= [HW,PCMCIA] BadgePAD 4
986 See Documentation/paride.txt.
988 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
991 See arch/parisc/kernel/pdc_chassis.c
994 See Documentation/paride.txt.
997 See Documentation/paride.txt.
999 pirq= [SMP,APIC] Manual mp-table setup
1000 See Documentation/i386/IO-APIC.txt.
1002 plip= [PPT,NET] Parallel port network link
1003 Format: { parport<nr> | timid | 0 }
1004 See also Documentation/parport.txt.
1007 { on | off | curr | res | no-curr | no-res }
1010 [ISAPNP] Exclude IRQs for the autoconfiguration
1013 [ISAPNP] Exclude DMAs for the autoconfiguration
1015 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1016 Ranges are in pairs (I/O port base and size).
1019 [ISAPNP] Exclude memory regions for the autoconfiguration
1020 Ranges are in pairs (memory base and size).
1022 profile= [KNL] Enable kernel profiling via /proc/profile
1023 { schedule | <number> }
1024 (param: schedule - profile schedule points}
1025 (param: profile step/bucket size as a power of 2 for
1026 statistical time based profiling)
1028 processor.max_cstate= [HW, ACPI]
1029 Limit processor to maximum C-state
1030 max_cstate=9 overrides any DMI blacklist limit.
1032 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1034 See Documentation/ramdisk.txt.
1036 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1037 probe for (bare|imps|exps).
1038 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1041 [HW,MOUSE] Try to reset the device after so many bad packets
1044 [HW,MOUSE] Set desired mouse resolution, in dpi.
1045 psmouse.smartscroll=
1046 [HW,MOUSE] Controls Logitech smartscroll autorepeat,
1047 0 = disabled, 1 = enabled (default).
1049 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1050 Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1053 See Documentation/paride.txt.
1055 quiet= [KNL] Disable log messages
1060 See Documentation/md.txt.
1062 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1063 See Documentation/ramdisk.txt.
1067 See Documentation/ramdisk.txt.
1069 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1070 New name for the ramdisk parameter.
1071 See Documentation/ramdisk.txt.
1073 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1074 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1075 See arch/*/kernel/reboot.c.
1077 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1079 resume= [SWSUSP] Specify the partition device for software suspension
1081 rhash_entries= [KNL,NET]
1082 Set number of hash buckets for route cache
1084 riscom8= [HW,SERIAL]
1085 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1087 ro [KNL] Mount root device read-only on boot
1089 root= [KNL] Root filesystem
1091 rootflags= [KNL] Set root filesystem mount option string
1093 rootfstype= [KNL] Set root filesystem type
1095 rw [KNL] Mount root device read-write on boot
1097 S [KNL] Run init in single mode
1100 See drivers/net/irda/sa1100_ir.c.
1103 Format: <io>,<irq>,<dma>,<dma2>
1105 sbni= [NET] Granch SBNI12 leased line adapter
1107 sbpcd= [HW,CD] Soundblaster CD adapter
1109 See a comment before function sbpcd_setup() in
1110 drivers/cdrom/sbpcd.c.
1112 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1113 Format: <io>[,<timeout>[,<isapnp>]]
1115 scsi_debug_*= [SCSI]
1116 See drivers/scsi/scsi_debug.c.
1118 scsi_default_dev_flags=
1119 [SCSI] SCSI default device flags
1122 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1123 Format: <vendor>:<model>:<flags>
1124 (flags are integer value)
1126 scsi_logging= [SCSI]
1128 serialnumber [BUGS=IA-32]
1130 sf16fm= [HW] SF16FMI radio driver for Linux
1133 sg_def_reserved_size=
1137 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1140 Maximal number of shapers.
1143 See header of drivers/scsi/sim710.c.
1149 Format: <io>,<irq>,<dma>
1150 See header of drivers/cdrom/sjcd.c.
1155 Format: <io1>[,<io2>[,...,<io8>]]
1157 snd-ad1816a= [HW,ALSA]
1159 snd-ad1848= [HW,ALSA]
1161 snd-ali5451= [HW,ALSA]
1163 snd-als100= [HW,ALSA]
1165 snd-als4000= [HW,ALSA]
1167 snd-azt2320= [HW,ALSA]
1169 snd-cmi8330= [HW,ALSA]
1171 snd-cmipci= [HW,ALSA]
1173 snd-cs4231= [HW,ALSA]
1175 snd-cs4232= [HW,ALSA]
1177 snd-cs4236= [HW,ALSA]
1179 snd-cs4281= [HW,ALSA]
1181 snd-cs46xx= [HW,ALSA]
1183 snd-dt019x= [HW,ALSA]
1185 snd-dummy= [HW,ALSA]
1187 snd-emu10k1= [HW,ALSA]
1189 snd-ens1370= [HW,ALSA]
1191 snd-ens1371= [HW,ALSA]
1193 snd-es968= [HW,ALSA]
1195 snd-es1688= [HW,ALSA]
1197 snd-es18xx= [HW,ALSA]
1199 snd-es1938= [HW,ALSA]
1201 snd-es1968= [HW,ALSA]
1203 snd-fm801= [HW,ALSA]
1205 snd-gusclassic= [HW,ALSA]
1207 snd-gusextreme= [HW,ALSA]
1209 snd-gusmax= [HW,ALSA]
1213 snd-ice1712= [HW,ALSA]
1215 snd-intel8x0= [HW,ALSA]
1217 snd-interwave= [HW,ALSA]
1222 snd-korg1212= [HW,ALSA]
1224 snd-maestro3= [HW,ALSA]
1226 snd-mpu401= [HW,ALSA]
1228 snd-mtpav= [HW,ALSA]
1230 snd-nm256= [HW,ALSA]
1232 snd-opl3sa2= [HW,ALSA]
1240 snd-opti93x= [HW,ALSA]
1244 snd-rme32= [HW,ALSA]
1246 snd-rme96= [HW,ALSA]
1248 snd-rme9652= [HW,ALSA]
1254 snd-sbawe= [HW,ALSA]
1256 snd-serial= [HW,ALSA]
1258 snd-sgalaxy= [HW,ALSA]
1260 snd-sonicvibes= [HW,ALSA]
1265 snd-sun-cs4231= [HW,ALSA]
1267 snd-trident= [HW,ALSA]
1269 snd-usb-audio= [HW,ALSA,USB]
1271 snd-via82xx= [HW,ALSA]
1273 snd-virmidi= [HW,ALSA]
1275 snd-wavefront= [HW,ALSA]
1277 snd-ymfpci= [HW,ALSA]
1279 sonicvibes= [HW,OSS]
1283 Format: <io>[,<irq>]
1285 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1286 See Documentation/sonypi.txt
1288 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1289 See Documentation/specialix.txt.
1291 spia_io_base= [HW,MTD]
1297 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1299 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1300 See Documentation/scsi/st.txt.
1303 See header of drivers/scsi/seagate.c.
1307 Set the STI (builtin display/keyboard on the HP-PARISC
1308 machines) console (graphic card) which should be used
1309 as the initial boot-console.
1310 See also comment in drivers/video/console/sticore.c.
1313 See comment in drivers/video/console/sticore.c.
1316 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1318 stram_swap= [HW,M68k]
1320 swiotlb= [IA-64] Number of I/O TLB slabs
1324 sym53c416= [HW,SCSI]
1325 See header of drivers/scsi/sym53c416.c.
1327 sym53c8xx= [HW,SCSI]
1328 See Documentation/scsi/ncr53c8xx.txt.
1331 See header of drivers/scsi/t128.c.
1335 thash_entries= [KNL,NET]
1336 Set number of hash buckets for TCP connection
1339 See header of drivers/char/tipar.c.
1341 tiusb= [HW,USB] Texas Instruments' USB GraphLink (aka SilverLink)
1345 See header of drivers/scsi/seagate.c.
1348 See comment before function dc390_setup() in
1349 drivers/scsi/tmscsim.c.
1353 trix= [HW,OSS] MediaTrix AudioTrix Pro
1354 Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1356 tsdev.xres= [TS] Horizontal screen resolution.
1357 tsdev.yres= [TS] Vertical screen resolution.
1359 turbografx.map[2|3]=
1360 [HW,JOY] TurboGraFX parallel port interface
1361 Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1362 See also Documentation/input/joystick-parport.txt
1364 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1365 See header of drivers/scsi/u14-34f.c.
1373 usb-handoff [HW] Enable early USB BIOS -> OS handoff
1375 video= [FB] Frame buffer configuration
1376 See Documentation/fb/modedb.txt.
1378 vga= [BOOT,IA-32] Select a particular video mode
1379 See Documentation/i386/boot.txt and Documentation/svga.txt.
1380 Use vga=ask for menu.
1381 This is actually a boot loader parameter; the value is
1382 passed to the kernel using a special protocol.
1384 vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
1385 size of <nn>. This can be used to increase the
1386 minimum size (128MB on x86). It can also be used to
1387 decrease the size and leave more room for directly
1394 waveartist= [HW,OSS]
1395 Format: <io>,<irq>,<dma>,<dma2>
1398 See header of drivers/scsi/wd33c93.c.
1401 See header of drivers/scsi/wd7000.c.
1404 See Documentation/watchdog/watchdog.txt.
1406 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1407 xd_geo= See header of drivers/block/xd.c.
1409 xirc2ps_cs= [NET,PCMCIA]
1410 Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1416 The last known update (for 2.4.0) - the changelog was not kept before.
1417 2000-06-?? Mr. Unknown
1419 Update for 2.5.49, description for most of the options introduced,
1420 references to other documentation (C files, READMEs, ..), added S390,
1421 PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1423 2002-11-24 Petr Baudis <pasky@ucw.cz>
1424 Randy Dunlap <randy.dunlap@verizon.net>
1428 Add documentation for ALSA options.
1429 Add more DRM drivers.