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
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 }
367 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
372 cs89x0_media= [HW,NET]
373 Format: { rj45 | aui | bnc }
375 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
378 See header of drivers/s390/block/dasd_devmap.c.
380 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
381 (one device per port)
382 Format: <port#>,<type>
383 See also Documentation/input/joystick-parport.txt
385 debug [KNL] Enable kernel debugging (events log level).
388 Format: <area>[,<node>]
389 See also Documentation/networking/decnet.txt.
392 See Documentation/filesystems/devfs/boot-options.
395 Set number of hash buckets for dentry cache.
398 IO parameters + enable/disable command.
400 digiepca= [HW,SERIAL]
401 See drivers/char/README.epca and
402 Documentation/digiepca.txt.
404 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
406 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
408 dmasound= [HW,OSS] Sound subsystem buffers
414 earlyprintk= [IA-32, X86-64]
416 earlyprintk=serial[,ttySn[,baudrate]]
418 Append ,keep to not disable it when the real console
421 Only vga or serial at a time, not both.
423 Currently only ttyS0 and ttyS1 are supported.
425 Interaction with the standard serial driver is not
428 The VGA output is eventually overwritten by the real
438 Format: {"of[f]" | "sk[ipmbr]"}
439 See comment in arch/i386/boot/edd.S
442 Format: <id>,<membase>,<irq>
444 eisa_irq_edge= [PARISC,HW]
445 See header of drivers/parisc/eisa.c.
448 See comment before function elanfreq_setup() in
449 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
452 Format: {"as"|"cfq"|"deadline"|"noop"}
453 See Documentation/block/as-iosched.txt
454 and Documentation/block/deadline-iosched.txt for details.
456 enforcing [SELINUX] Set initial enforcing status.
458 See security/selinux/Kconfig help text.
459 0 -- permissive (log only, no denials).
460 1 -- enforcing (deny and log).
462 Value can be changed at runtime via /selinux/enforce.
465 Format: <lineout>[,<micbias>]
466 See also header of sound/oss/es1370.c.
469 Format: <spdif>,[<nomix>,[<amplifier>]]
470 See also header of sound/oss/es1371.c.
472 ether= [HW,NET] Ethernet cards parameters
473 This option is obsoleted by the "netdev=" option, which
474 has equivalent usage. See its documentation for details.
476 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
480 See header of drivers/scsi/fd_mcs.c.
483 See header of drivers/scsi/fdomain.c.
486 See Documentation/floppy.txt.
488 ftape= [HW] Floppy Tape subsystem debugging options.
489 See Documentation/ftape.txt.
492 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
493 support via parallel port (up to 5 devices per port)
494 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
495 See also Documentation/input/joystick-parport.txt
500 See header of drivers/scsi/gdth.c.
502 gpt [EFI] Forces disk with valid GPT signature but
503 invalid Protective MBR to be treated as GPT.
508 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
511 Format: <io>,<irq>,<dma>,<dma16>
515 hashdist= [KNL,NUMA] Large hashes allocated during boot
516 are distributed across NUMA nodes. Defaults on
517 for IA-64, off otherwise.
519 hcl= [IA-64] SGI's Hardware Graph compatibility layer
521 hd= [EIDE] (E)IDE hard drive subsystem geometry
522 Format: <cyl>,<head>,<sect>
524 hd?= [HW] (E)IDE subsystem
525 hd?lun= See Documentation/ide.txt.
527 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
528 size of <nn>. This works even on boxes that have no
529 highmem otherwise. This also works to reduce highmem
530 size on bigger boxes.
533 See Documentation/isdn/README.HiSax.
535 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
537 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
539 i8042.direct [HW] Put keyboard port into non-translated mode
540 i8042.dumbkbd [HW] Pretend that controlled can only read data from
541 keyboard and can not control its state
542 (Don't attempt to blink the leds)
543 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
544 i8042.nomux [HW] Don't check presence of an active multiplexing
546 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
549 [HW] Frequency with which keyboard LEDs should blink
550 when kernel panics (default is 0.5 sec)
551 i8042.reset [HW] Reset the controller during init and cleanup
552 i8042.unlock [HW] Unlock (ignore) the keylock
556 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
557 does not match list of supported models.
559 [HW] Report power status in /proc/i8k
560 (disabled by default)
561 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
564 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
565 See Documentation/mca.txt.
568 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
570 ide= [HW] (E)IDE subsystem
571 Format: ide=nodma or ide=doubler or ide=reverse
572 See Documentation/ide.txt.
574 ide?= [HW] (E)IDE subsystem
575 Format: ide?=noprobe or chipset specific parameters.
576 See Documentation/ide.txt.
578 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
579 See Documentation/ide.txt.
582 Format: idle=poll or idle=halt
585 Set number of hash buckets for inode cache.
588 See header of drivers/scsi/in2000.c.
592 Run specified binary instead of /sbin/init as init
595 initcall_debug [KNL] Trace initcalls as they are executed. Useful
596 for working out where the kernel is dying during
599 initrd= [BOOT] Specify the location of the initial ramdisk
601 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
606 io7= [HW] IO7 for Marvel based alpha systems
607 See comment before marvel_specify_io7 in
608 arch/alpha/kernel/core_marvel.c.
611 See Documentation/nfsroot.txt.
613 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
614 See comment before ip2_setup() in drivers/char/ip2.c.
616 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
617 See header of drivers/scsi/ips.c.
620 Format: <RDP>, <reset>, <pci_scan>, <verbosity>
622 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
623 Format: <cpu number>,...,<cpu number>
624 This option can be used to specify one or more CPUs
625 to isolate from the general SMP balancing and scheduling
626 algorithms. The only way to move a process onto or off
627 an "isolated" CPU is via the CPU affinity syscalls.
628 <cpu number> begins at 0 and the maximum value is
629 "number of CPUs in system - 1".
631 This option is the preferred way to isolate CPUs. The
632 alternative - manually setting the CPU mask of all tasks
633 in the system can cause problems and suboptimal load
634 balancer performance.
637 Format: <io>,<irq>,<dma>,<setup>
641 js= [HW,JOY] Analog joystick
642 See Documentation/input/joystick.txt.
646 kstack=N [IA-32, X86-64] Print N words from the kernel stack
651 lapic [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
653 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
654 Format: addr:<io>,irq:<irq>
657 See function print_params() in arch/ia64/sn/kernel/llsc4.c.
659 load_ramdisk= [RAM] List of ramdisks to load from floppy
660 See Documentation/ramdisk.txt.
666 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
669 loglevel= All Kernel Messages with a loglevel smaller than the
670 console loglevel will be printed to the console. It can
671 also be changed with klogd or other programs. The
672 loglevels are defined as follows:
674 0 (KERN_EMERG) system is unusable
675 1 (KERN_ALERT) action must be taken immediately
676 2 (KERN_CRIT) critical conditions
677 3 (KERN_ERR) error conditions
678 4 (KERN_WARNING) warning conditions
679 5 (KERN_NOTICE) normal but significant condition
680 6 (KERN_INFO) informational
681 7 (KERN_DEBUG) debug-level messages
683 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
684 Format is n, nk, nM. n must be a power of two. The
685 default is set in kernel config.
687 lp=0 [LP] Specify parallel ports to use, e.g,
688 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
689 lp=reset first parallel port). 'lp=0' disables the
690 lp=auto printer driver. 'lp=reset' (which can be
691 specified in addition to the ports) causes
692 attached printers to be reset. Using
693 lp=port1,port2,... specifies the parallel ports
694 to associate lp devices with, starting with
695 lp0. A port specification may be 'none' to skip
696 that lp device, or a parport name such as
697 'parport0'. Specifying 'lp=auto' instead of a
698 port specification list means that device IDs
699 from each port should be examined, to see if
700 an IEEE 1284-compliant printer is attached; if
701 so, the driver will manage that printer.
702 See also header of drivers/char/lp.c.
705 Sets loops_per_jiffy to given constant, thus avoiding
706 time-consuming boot-time autodetection (up to 250 ms per
707 CPU). 0 enables autodetection (default). To determine
708 the correct value for your kernel, boot with normal
709 autodetection and see what value is printed. Note that
710 on SMP systems the preset will be applied to all CPUs,
711 which is likely to cause problems if your CPUs need
712 significantly divergent settings. An incorrect value
713 will cause delays in the kernel to be wrong, leading to
714 unpredictable I/O errors and other breakage. Although
715 unlikely, in the extreme case this might damage your
719 Format: <io>,<irq>,<dma>
722 Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
725 Format: <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
728 Force the use of a particular machine-vector (machvec) in a generic
729 kernel. Example: machvec=hpzx1_swiotlb
732 Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
737 max_loop= [LOOP] Maximum number of loopback devices that can
741 maxcpus= [SMP] Maximum number of processors that an SMP kernel
744 max_luns= [SCSI] Maximum number of LUNs to probe
745 Should be between 1 and 2^32-1.
748 [SCSI] Maximum number of LUNs received
749 Should be between 1 and 16384.
751 mca-pentium [BUGS=IA-32]
756 Format: <port>,<irq>,<mitsumi_bug_93_wait>
760 mce [IA-32] Machine Check Exception
762 md= [HW] RAID subsystems devices and level
763 See Documentation/md.txt.
766 Format: <first>,<last>
767 Specifies range of consoles to be captured by the MDA.
769 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
770 Amount of memory to be used when the kernel is not able
771 to see the whole system memory or for test.
772 [IA-32] Use together with memmap= to avoid physical
773 address space collisions. Without memmap= PCI devices
774 could be placed at addresses belonging to unused RAM.
776 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
779 memmap=exactmap [KNL,IA-32] Enable setting of an exact
780 E820 memory map, as specified by the user.
781 Such memmap=exactmap lines can be constructed based on
782 BIOS output or other requirements. See the memmap=nn@ss
785 memmap=nn[KMG]@ss[KMG]
786 [KNL] Force usage of a specific region of memory
787 Region of memory to be used, from ss to ss+nn.
789 memmap=nn[KMG]#ss[KMG]
790 [KNL,ACPI] Mark specific memory as ACPI data.
791 Region of memory to be used, from ss to ss+nn.
793 memmap=nn[KMG]$ss[KMG]
794 [KNL,ACPI] Mark specific memory as reserved.
795 Region of memory to be used, from ss to ss+nn.
797 meye.*= [HW] Set MotionEye Camera parameters
798 See Documentation/video4linux/meye.txt.
803 [MOUSE] Maximum time between finger touching and
804 leaving touchpad surface for touch to be considered
805 a tap and be reported as a left button click (for
806 touchpads working in absolute mode only).
808 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
809 reporting absolute coordinates, such as tablets
810 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
811 reporting absolute coordinates, such as tablets
817 Format: <name>,<region-number>,<size>,<offset>
820 Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
823 See drivers/mtd/cmdline.c.
825 mtouchusb.raw_coordinates=
826 [HW] Make the MicroTouch USB driver use raw coordinates ('y', default)
827 or cooked coordinates ('n')
829 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
832 See header of drivers/scsi/NCR_D700.c.
838 ncr53c400a= [HW,SCSI]
840 ncr53c406a= [HW,SCSI]
844 netdev= [NET] Network devices parameters
845 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
846 Note that mem_start is often overloaded to mean
847 something different and driver-specific.
850 See Documentation/nfsroot.txt.
852 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
853 See Documentation/nfsroot.txt.
855 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
857 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
858 emulation library even if a 387 maths coprocessor
863 noapic [SMP,APIC] Tells the kernel to not make use of any
864 IOAPICs that may be present in the system.
866 noasync [HW,M68K] Disables async and sync negotiation for
869 nobats [PPC] Do not use BATs for mapping kernel lowmem
870 on "Classic" PPC cores.
874 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
878 noexec [IA-32, X86-64]
879 noexec=on: enable non-executable mappings (default)
880 noexec=off: disable nn-executable mappings
886 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
887 instruction doesn't work correctly and not to
890 nohalt [IA-64] Tells the kernel not to use the power saving
891 function PAL_HALT_LIGHT when idle. This increases
892 power-consumption. On the positive side, it reduces
893 interrupt wake-up latency, which may improve performance
894 in certain environments such as networked servers or
897 noirqdebug [IA-32] Disables the code which attempts to detect and
898 disable unhandled interrupt sources.
900 noisapnp [ISAPNP] Disables ISA PnP code.
902 noinitrd [RAM] Tells the kernel not to load any configured
907 nolapic [IA-32,APIC] Do not enable or use the local APIC.
909 noltlbs [PPC] Do not use large page/tlb entries for kernel
910 lowmem mapping on PPC40x.
912 nomce [IA-32] Machine Check Exception
914 noresidual [PPC] Don't use residual data on PReP machines.
916 noresume [SWSUSP] Disables resume and restore original swap space.
918 no-scroll [VGA] Disables scrollback.
919 This is required for the Braillex ib80-piezo Braille
920 reader made by F.H. Papenmeier (Germany).
924 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
926 nosync [HW,M68K] Disables sync negotiation for all devices.
928 notsc [BUGS=IA-32] Disable Time Stamp Counter
930 nousb [USB] Disable the USB subsystem
938 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
941 Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
944 Use timer interrupt instead of performance counters
949 osst= [HW,SCSI] SCSI Tape Driver
950 Format: <buffer_size>,<write_threshold>
951 See also Documentation/scsi/st.txt.
953 panic= [KNL] Kernel behaviour on panic
956 parkbd.port= [HW] Parallel port number the keyboard adapter is
957 connected to, default is 0.
959 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
960 0 for XT, 1 for AT (default is AT).
963 parport=0 [HW,PPT] Specify parallel ports. 0 disables.
964 parport=auto Use 'auto' to force the driver to use
965 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
966 default is to ignore detected IRQ/DMA
967 settings because of possible
968 conflicts). You can specify the base
969 address, IRQ, and DMA settings; IRQ and
970 DMA should be numbers, or 'auto' (for
971 using detected settings on that
972 particular port), or 'nofifo' (to avoid
973 using a FIFO even if it is detected).
974 Parallel ports are assigned in the
975 order they are specified on the command
976 line, starting with parport0.
979 [HW,PPT] Configure VIA parallel port to
980 operate in specific mode. This is
981 necessary on Pegasos computer where
982 firmware has no options for setting up
983 parallel port mode and sets it to
984 spp. Currently this function knows
986 Format: [spp|ps2|epp|ecp|ecpepp]
989 Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
992 See header of drivers/scsi/pas16.c.
997 See header of drivers/block/paride/pcd.c.
998 See also Documentation/paride.txt.
1000 pci=option[,option...] [PCI] various PCI subsystem options:
1001 off [IA-32] don't probe for the PCI bus
1002 bios [IA-32] force use of PCI BIOS, don't access
1003 the hardware directly. Use this if your machine
1004 has a non-standard PCI host bridge.
1005 nobios [IA-32] disallow use of PCI BIOS, only direct
1006 hardware access methods are allowed. Use this
1007 if you experience crashes upon bootup and you
1008 suspect they are caused by the BIOS.
1009 conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
1010 conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
1011 nosort [IA-32] Don't sort PCI devices according to
1012 order given by the PCI BIOS. This sorting is done
1013 to get a device order compatible with older kernels.
1014 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1015 routing table. These calls are known to be buggy
1016 on several machines and they hang the machine when used,
1017 but on other computers it's the only way to get the
1018 interrupt routing table. Try this option if the kernel
1019 is unable to allocate IRQs or discover secondary PCI
1020 buses on your motherboard.
1021 rom [IA-32] Assign address space to expansion ROMs.
1022 Use with caution as certain devices share address
1023 decoders between ROMs and other resources.
1024 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned
1025 automatically to PCI devices. You can make the kernel
1026 exclude IRQs of your ISA cards this way.
1027 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
1028 if the kernel is unable to find your secondary buses
1029 and you want to tell it explicitly which ones they are.
1030 assign-busses [IA-32] Always assign all PCI bus
1031 numbers ourselves, overriding
1032 whatever the firmware may have
1034 usepirqmask [IA-32] Honor the possible IRQ mask
1035 stored in the BIOS $PIR table. This is
1036 needed on some systems with broken
1037 BIOSes, notably some HP Pavilion N5400
1038 and Omnibook XE3 notebooks. This will
1039 have no effect if ACPI IRQ routing is
1041 noacpi [IA-32] Do not use ACPI for IRQ routing
1042 or for PCI scanning.
1043 routeirq Do IRQ routing for all PCI devices.
1044 This is normally done in pci_enable_device(),
1045 so this option is a temporary workaround
1046 for broken drivers that don't call it.
1048 firmware [ARM] Do not re-enumerate the bus but
1049 instead just use the configuration
1050 from the bootloader. This is currently
1051 used on IXP2000 systems where the
1052 bus has to be configured a certain way
1055 pcmv= [HW,PCMCIA] BadgePAD 4
1058 See Documentation/paride.txt.
1060 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1063 See arch/parisc/kernel/pdc_chassis.c
1066 See Documentation/paride.txt.
1069 See Documentation/paride.txt.
1071 pirq= [SMP,APIC] Manual mp-table setup
1072 See Documentation/i386/IO-APIC.txt.
1074 plip= [PPT,NET] Parallel port network link
1075 Format: { parport<nr> | timid | 0 }
1076 See also Documentation/parport.txt.
1082 { on | off | curr | res | no-curr | no-res }
1085 [ISAPNP] Exclude IRQs for the autoconfiguration
1088 [ISAPNP] Exclude DMAs for the autoconfiguration
1090 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1091 Ranges are in pairs (I/O port base and size).
1094 [ISAPNP] Exclude memory regions for the autoconfiguration
1095 Ranges are in pairs (memory base and size).
1097 profile= [KNL] Enable kernel profiling via /proc/profile
1098 { schedule | <number> }
1099 (param: schedule - profile schedule points}
1100 (param: profile step/bucket size as a power of 2 for
1101 statistical time based profiling)
1103 processor.max_cstate= [HW, ACPI]
1104 Limit processor to maximum C-state
1105 max_cstate=9 overrides any DMI blacklist limit.
1107 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1109 See Documentation/ramdisk.txt.
1111 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1112 probe for (bare|imps|exps).
1113 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1116 [HW,MOUSE] Try to reset the device after so many bad packets
1119 [HW,MOUSE] Set desired mouse resolution, in dpi.
1120 psmouse.smartscroll=
1121 [HW,MOUSE] Controls Logitech smartscroll autorepeat,
1122 0 = disabled, 1 = enabled (default).
1124 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1125 Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1128 See Documentation/paride.txt.
1130 quiet= [KNL] Disable log messages
1135 See Documentation/md.txt.
1137 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1138 See Documentation/ramdisk.txt.
1142 See Documentation/ramdisk.txt.
1144 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1145 New name for the ramdisk parameter.
1146 See Documentation/ramdisk.txt.
1148 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1149 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1150 See arch/*/kernel/reboot.c.
1152 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1154 resume= [SWSUSP] Specify the partition device for software suspension
1156 rhash_entries= [KNL,NET]
1157 Set number of hash buckets for route cache
1159 riscom8= [HW,SERIAL]
1160 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1162 ro [KNL] Mount root device read-only on boot
1164 root= [KNL] Root filesystem
1166 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1167 mount the root filesystem
1169 rootflags= [KNL] Set root filesystem mount option string
1171 rootfstype= [KNL] Set root filesystem type
1173 rw [KNL] Mount root device read-write on boot
1175 S [KNL] Run init in single mode
1178 See drivers/net/irda/sa1100_ir.c.
1181 Format: <io>,<irq>,<dma>,<dma2>
1183 sbni= [NET] Granch SBNI12 leased line adapter
1185 sbpcd= [HW,CD] Soundblaster CD adapter
1187 See a comment before function sbpcd_setup() in
1188 drivers/cdrom/sbpcd.c.
1190 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1191 Format: <io>[,<timeout>[,<isapnp>]]
1193 scsi_debug_*= [SCSI]
1194 See drivers/scsi/scsi_debug.c.
1196 scsi_default_dev_flags=
1197 [SCSI] SCSI default device flags
1200 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1201 Format: <vendor>:<model>:<flags>
1202 (flags are integer value)
1204 scsi_logging= [SCSI]
1206 selinux [SELINUX] Disable or enable SELinux at boot time.
1207 Format: { "0" | "1" }
1208 See security/selinux/Kconfig help text.
1211 Default value is set via kernel config option.
1212 If enabled at boot time, /selinux/disable can be used
1213 later to disable prior to initial policy load.
1215 serialnumber [BUGS=IA-32]
1217 sg_def_reserved_size=
1221 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1224 Maximal number of shapers.
1227 See header of drivers/scsi/sim710.c.
1233 Format: <io>,<irq>,<dma>
1234 See header of drivers/cdrom/sjcd.c.
1239 Format: <io1>[,<io2>[,...,<io8>]]
1241 snd-ad1816a= [HW,ALSA]
1243 snd-ad1848= [HW,ALSA]
1245 snd-ali5451= [HW,ALSA]
1247 snd-als100= [HW,ALSA]
1249 snd-als4000= [HW,ALSA]
1251 snd-azt2320= [HW,ALSA]
1253 snd-cmi8330= [HW,ALSA]
1255 snd-cmipci= [HW,ALSA]
1257 snd-cs4231= [HW,ALSA]
1259 snd-cs4232= [HW,ALSA]
1261 snd-cs4236= [HW,ALSA]
1263 snd-cs4281= [HW,ALSA]
1265 snd-cs46xx= [HW,ALSA]
1267 snd-dt019x= [HW,ALSA]
1269 snd-dummy= [HW,ALSA]
1271 snd-emu10k1= [HW,ALSA]
1273 snd-ens1370= [HW,ALSA]
1275 snd-ens1371= [HW,ALSA]
1277 snd-es968= [HW,ALSA]
1279 snd-es1688= [HW,ALSA]
1281 snd-es18xx= [HW,ALSA]
1283 snd-es1938= [HW,ALSA]
1285 snd-es1968= [HW,ALSA]
1287 snd-fm801= [HW,ALSA]
1289 snd-gusclassic= [HW,ALSA]
1291 snd-gusextreme= [HW,ALSA]
1293 snd-gusmax= [HW,ALSA]
1297 snd-ice1712= [HW,ALSA]
1299 snd-intel8x0= [HW,ALSA]
1301 snd-interwave= [HW,ALSA]
1306 snd-korg1212= [HW,ALSA]
1308 snd-maestro3= [HW,ALSA]
1310 snd-mpu401= [HW,ALSA]
1312 snd-mtpav= [HW,ALSA]
1314 snd-nm256= [HW,ALSA]
1316 snd-opl3sa2= [HW,ALSA]
1324 snd-opti93x= [HW,ALSA]
1328 snd-rme32= [HW,ALSA]
1330 snd-rme96= [HW,ALSA]
1332 snd-rme9652= [HW,ALSA]
1338 snd-sbawe= [HW,ALSA]
1340 snd-serial= [HW,ALSA]
1342 snd-sgalaxy= [HW,ALSA]
1344 snd-sonicvibes= [HW,ALSA]
1349 snd-sun-cs4231= [HW,ALSA]
1351 snd-trident= [HW,ALSA]
1353 snd-usb-audio= [HW,ALSA,USB]
1355 snd-via82xx= [HW,ALSA]
1357 snd-virmidi= [HW,ALSA]
1359 snd-wavefront= [HW,ALSA]
1361 snd-ymfpci= [HW,ALSA]
1363 sonicvibes= [HW,OSS]
1367 Format: <io>[,<irq>]
1369 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1370 See Documentation/sonypi.txt
1372 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1373 See Documentation/specialix.txt.
1375 spia_io_base= [HW,MTD]
1381 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1383 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1384 See Documentation/scsi/st.txt.
1387 See header of drivers/scsi/seagate.c.
1391 Set the STI (builtin display/keyboard on the HP-PARISC
1392 machines) console (graphic card) which should be used
1393 as the initial boot-console.
1394 See also comment in drivers/video/console/sticore.c.
1397 See comment in drivers/video/console/sticore.c.
1400 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1402 stram_swap= [HW,M68k]
1404 swiotlb= [IA-64] Number of I/O TLB slabs
1408 sym53c416= [HW,SCSI]
1409 See header of drivers/scsi/sym53c416.c.
1412 See header of drivers/scsi/t128.c.
1416 thash_entries= [KNL,NET]
1417 Set number of hash buckets for TCP connection
1419 time Show timing data prefixed to each printk message line
1421 tipar.timeout= [HW,PPT]
1422 Set communications timeout in tenths of a second
1425 tipar.delay= [HW,PPT]
1426 Set inter-bit delay in microseconds (default 10).
1429 See header of drivers/scsi/seagate.c.
1432 See comment before function dc390_setup() in
1433 drivers/scsi/tmscsim.c.
1437 trix= [HW,OSS] MediaTrix AudioTrix Pro
1438 Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1440 tsdev.xres= [TS] Horizontal screen resolution.
1441 tsdev.yres= [TS] Vertical screen resolution.
1443 turbografx.map[2|3]=
1444 [HW,JOY] TurboGraFX parallel port interface
1445 Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1446 See also Documentation/input/joystick-parport.txt
1448 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1449 See header of drivers/scsi/u14-34f.c.
1457 usb-handoff [HW] Enable early USB BIOS -> OS handoff
1460 [USBHID] The interval which mice are to be polled at.
1462 video= [FB] Frame buffer configuration
1463 See Documentation/fb/modedb.txt.
1465 vga= [BOOT,IA-32] Select a particular video mode
1466 See Documentation/i386/boot.txt and Documentation/svga.txt.
1467 Use vga=ask for menu.
1468 This is actually a boot loader parameter; the value is
1469 passed to the kernel using a special protocol.
1471 vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
1472 size of <nn>. This can be used to increase the
1473 minimum size (128MB on x86). It can also be used to
1474 decrease the size and leave more room for directly
1481 waveartist= [HW,OSS]
1482 Format: <io>,<irq>,<dma>,<dma2>
1485 See header of drivers/scsi/wd33c93.c.
1488 See header of drivers/scsi/wd7000.c.
1491 See Documentation/watchdog/watchdog.txt.
1493 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1494 xd_geo= See header of drivers/block/xd.c.
1496 xirc2ps_cs= [NET,PCMCIA]
1497 Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1503 The last known update (for 2.4.0) - the changelog was not kept before.
1504 2000-06-?? Mr. Unknown
1506 Update for 2.5.49, description for most of the options introduced,
1507 references to other documentation (C files, READMEs, ..), added S390,
1508 PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1510 2002-11-24 Petr Baudis <pasky@ucw.cz>
1511 Randy Dunlap <randy.dunlap@verizon.net>
1515 Add documentation for ALSA options.
1516 Add more DRM drivers.