1 July 2000 Kernel Parameters v2.4.0
4 The following is a consolidated list of the kernel parameters as implemented
5 by the __setup() macro and sorted into English Dictionary order (defined
6 as ignoring all punctuation and sorting digits before letters in a case
7 insensitive manner), and with descriptions where known.
9 The text in square brackets at the beginning of the description state the
10 restrictions on the kernel for the said kernel parameter to be valid. The
11 restrictions referred to are that the relevant option is valid if:
13 ACPI ACPI support is enabled.
14 APIC APIC support is enabled.
15 APM Advanced Power Management support is enabled.
16 AX25 Appropriate AX.25 support is enabled.
17 CD Appropriate CD support is enabled.
18 DEVFS devfs support is enabled.
19 DRM Direct Rendering Management support is enabled.
20 EFI EFI Partitioning (GPT) is enabled
21 EIDE EIDE/ATAPI support is enabled.
22 FB The frame buffer device is enabled.
23 HW Appropriate hardware is enabled.
24 IA-32 IA-32 aka i386 architecture is enabled.
25 IA-64 IA-64 architecture is enabled.
26 IP_PNP IP DCHP, BOOTP, or RARP is enabled.
27 ISAPNP ISA PnP code is enabled.
28 ISDN Appropriate ISDN support is enabled.
29 JOY Appropriate joystick support is enabled.
30 LP Printer support is enabled.
31 LOOP Loopback device support is enabled.
32 M68k M68k architecture is enabled.
33 MCA MCA bus support is enabled.
34 MDA MDA console support is enabled.
35 MOUSE Appropriate mouse support is enabled.
36 NET Appropriate network support is enabled.
37 NFS Appropriate NFS support is enabled.
38 PARIDE The ParIDE subsystem is enabled.
39 PCI PCI bus support is enabled.
40 PCMCIA The PCMCIA subsystem is enabled.
41 PNP Plug & Play support is enabled.
42 PPT Parallel port support is enabled.
43 PS2 Appropriate PS/2 support is enabled.
44 RAM RAM disk support is enabled.
45 SCSI Appropriate SCSI support is enabled.
46 SERIAL Serial support is enabled.
47 SMP The kernel is an SMP kernel.
48 SOUND Appropriate sound system support is enabled.
49 V4L Video For Linux support is enabled.
50 VGA The VGA console has been enabled.
51 VT Virtual terminal support is enabled.
52 XT IBM PC/XT MFM hard disk support is enabled.
54 In addition, the following text indicates that the option:
56 BUGS= Relates to possible processor bugs on the said processor.
57 KNL Is a kernel start-up parameter.
58 BOOT Is a boot loader parameter.
60 Parameters denoted with BOOT are actually interpreted by the boot
61 loader, and have no meaning to the kernel directly.
63 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
64 a trailing = on the name of any parameter states that that parameter will
65 be entered as an environment variable, whereas its absence indicates that
66 it will appear as a kernel argument readable via /proc/cmdline by programs
67 running once the system is up.
69 53c7xx= [HW,SCSI] Amiga SCSI controllers.
71 acpi= [HW,ACPI] Advanced Configuration and Power Interface
72 force Enable ACPI if default was off
73 off Disable ACPI if default was on
74 noirq Do not use ACPI for IRQ routing (see pci=noacpi)
75 ht Limit ACPI to boot-time LAPIC enumeration for HT,
76 disabling the run-time AML interpreter.
77 strict Be less tolerant of platforms that are not
78 strictly ACPI specification compliant.
80 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
81 Format: { level | edge | high | low }
83 acpi_irq_balance ACPI will balance active IRQs
84 acpi_irq_nobalance ACPI will not move active IRQs
85 acpi_irq_pci= If irq_balance, Clear listed IRQs for use by PCI
86 acpi_irq_isa= If irq_balance, Mark listed IRQs used by ISA
88 acpi_osi= [HW,ACPI] empty param disables _OSI
90 acpi_serialize [HW,ACPI] force serialization of AML methods
96 adb_buttons= [HW,MOUSE]
112 amijoy= [HW,JOY] Amiga joystick support
114 apm= [APM] Advanced Power Management.
122 atarimouse= [HW,MOUSE] Atari Mouse.
124 atascsi= [HW,SCSI] Atari SCSI.
128 aztcd= [HW,CD] Aztec CD driver.
130 baycom_epp= [HW,AX25]
132 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem.
134 baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Full
137 baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Half
140 bmouse= [HW,MOUSE,PS2] Bus mouse.
142 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards), most
143 bttv.radio= important insmod options are available as kernel args too.
144 bttv.pll= see Documentation/video4linux/bttv/Insmod-options
145 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
163 console= [KNL] output console + comm spec (speed, control,
174 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
184 debug [KNL] Enable kernel debugging (events log level).
190 digi= [HW,SERIAL] io parameters + enable/disable command.
192 digiepca= [HW,SERIAL]
194 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
197 dmasound= [HW,SOUND] (sound subsystem buffers).
213 ether= [HW,NET] Ethernet cards parameters (irq,
214 base_io_addr, mem_start, mem_end, name.
215 (mem_start is often overloaded to mean something
216 different and driver-specific).
224 ftape= [HW] Floppy Tape subsystem debugging options.
236 gpt [EFI] Forces disk with valid GPT signature but
237 invalid Protective MBR to be treated as GPT.
245 hd= [EIDE] (E)IDE hard drive subsystem geometry
246 (Cyl/heads/sectors) or tune parameters.
254 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter.
258 ide?= [HW] (E)IDE subsystem : config (iomem/irq), tuning or
259 debugging (serialize,reset,no{dma,tune,probe}) or
260 chipset specific parameters.
262 idebus= [HW] (E)IDE subsystem : VLB/PCI bus speed.
270 initrd= [BOOT] Specify the location of the initial ramdisk.
274 isapnp= [ISAPNP] Specify RDP, reset, pci_scan and verbosity.
276 isapnp_reserve_irq= [ISAPNP] Exclude IRQs for the autoconfiguration.
278 isapnp_reserve_dma= [ISAPNP] Exclude DMAs for the autoconfiguration.
280 isapnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration.
281 Ranges are in pairs (I/O port base and size).
283 isapnp_reserve_mem= [ISAPNP] Exclude memory regions for the autoconfiguration.
284 Ranges are in pairs (memory base and size).
290 js= [HW,JOY] Analog joystick
296 lapic [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
298 load_ramdisk= [RAM] List of ramdisks to load from floppy.
304 logi_busmouse= [HW, MOUSE]
306 lp=0 [LP] Specify parallel ports to use, e.g,
307 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
308 lp=reset first parallel port). 'lp=0' disables the
309 lp=auto printer driver. 'lp=reset' (which can be
310 specified in addition to the ports) causes
311 attached printers to be reset. Using
312 lp=port1,port2,... specifies the parallel ports
313 to associate lp devices with, starting with
314 lp0. A port specification may be 'none' to skip
315 that lp device, or a parport name such as
316 'parport0'. Specifying 'lp=auto' instead of a
317 port specification list means that device IDs
318 from each port should be examined, to see if
319 an IEEE 1284-compliant printer is attached; if
320 so, the driver will manage that printer.
332 max_loop=[0-255] [LOOP] Set the maximum number of loopback devices
335 maxcpus= [SMP] States the maximum number of processors that
336 an SMP kernel should make use of.
338 max_scsi_luns= [SCSI]
340 mca-pentium [BUGS=IA-32]
346 md= [HW] RAID subsystems devices and level.
354 mem=exactmap [KNL,BOOT,IA-32] enable setting of an exact
355 e820 memory map, as specified by the user.
356 Such mem=exactmap lines can be constructed
357 based on BIOS output or other requirements.
359 mem=nn[KMG] [KNL,BOOT] force use of a specific amount of
360 memory; to be used when the kernel is not able
361 to see the whole system memory or for test.
364 [KNL,BOOT] Force usage of a specific region of memory
365 Region of memory to be used, from ss to ss+nn.
368 [KNL,BOOT,ACPI] Mark specific memory as ACPI data.
369 Region of memory to be used, from ss to ss+nn.
372 [KNL,BOOT,ACPI] Mark specific memory as reserved.
373 Region of memory to be used, from ss to ss+nn.
381 msmouse= [HW,MOUSE] Microsoft Mouse.
387 ncr53c400a= [HW,SCSI]
389 ncr53c406a= [HW,SCSI]
393 netdev= [NET] Ethernet cards parameters (irq,
394 base_io_addr, mem_start, mem_end, name.
395 (mem_start is often overloaded to mean something
396 different and driver-specific).
401 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
403 nmi_watchdog= [KNL,BUGS=IA-32] debugging features for SMP kernels.
405 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
406 emulation library even if a 387 maths coprocessor
411 noapic [SMP,APIC] Tells the kernel not to make use of any
412 APIC that may be present on the system.
414 noasync [HW, M68K] Disables async and sync negotiation for
419 nodisconnect [HW,SCSI, M68K] Disables SCSI disconnects.
423 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
424 instruction doesn't work correctly and not to
427 noisapnp [ISAPNP] Disables ISA PnP code.
429 noinitrd [RAM] Tells the kernel not to load any configured
434 nokeyb [HW] Skip console keyboard initialization for systems
435 without a console keyboard, removable keyboard, or
436 bladecenters with a USB console keyboard switch, etc.
438 nolapic [IA-32,APIC] Do not enable or use the local APIC.
442 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
444 nosync [HW, M68K] Disables sync negotiation for all devices.
446 notsc [BUGS=IA-32] Disable Time Stamp Counter
458 panic= [KNL] kernel behaviour on panic.
460 parport=0 [HW,PPT] Specify parallel ports. 0 disables.
461 parport=auto Use 'auto' to force the driver to use
462 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
463 default is to ignore detected IRQ/DMA
464 settings because of possible
465 conflicts). You can specify the base
466 address, IRQ, and DMA settings; IRQ and
467 DMA should be numbers, or 'auto' (for
468 using detected settings on that
469 particular port), or 'nofifo' (to avoid
470 using a FIFO even if it is detected).
471 Parallel ports are assigned in the
472 order they are specified on the command
473 line, starting with parport0.
483 pci=option[,option...] [PCI] various PCI subsystem options:
484 off [IA-32] don't probe for the PCI bus
485 bios [IA-32] force use of PCI BIOS, don't access
486 the hardware directly. Use this if your machine
487 has a non-standard PCI host bridge.
488 nobios [IA-32] disallow use of PCI BIOS, only direct
489 hardware access methods are allowed. Use this
490 if you experience crashes upon bootup and you
491 suspect they are caused by the BIOS.
492 conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
493 conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
494 nosort [IA-32] Don't sort PCI devices according to
495 order given by the PCI BIOS. This sorting is done
496 to get a device order compatible with older kernels.
497 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
498 routing table. These calls are known to be buggy
499 on several machines and they hang the machine when used,
500 but on other computers it's the only way to get the
501 interrupt routing table. Try this option if the kernel
502 is unable to allocate IRQs or discover secondary PCI
503 buses on your motherboard.
504 rom [IA-32] Assign address space to expansion ROMs.
505 Use with caution as certain devices share address
506 decoders between ROMs and other resources.
507 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned
508 automatically to PCI devices. You can make the kernel
509 exclude IRQs of your ISA cards this way.
510 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
511 if the kernel is unable to find your secondary buses
512 and you want to tell it explicitly which ones they are.
513 assign-busses [IA-32] Always assign all PCI bus
514 numbers ourselves, overriding
515 whatever the firmware may have
524 pirq= [SMP,APIC] mp-table.
526 plip= [PPT,NET] Parallel port network link.
528 profile= [KNL] enable kernel profiling via /proc/profile
529 (param: profile step/bucket size as a power of 2)
531 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
538 quiet= [KNL] Disable log messages.
544 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated].
549 ramdisk_size= [RAM] New name for the ramdisk parameter.
551 ramdisk_start= [RAM] Starting block of RAM disk image (so you can
552 place it after the kernel image on a boot floppy).
556 reserve= [KNL,BUGS] force the kernel to ignore some iomem area.
560 ro [KNL] Mount root device read-only on boot.
562 root= [KNL] root filesystem.
564 rootflags= [KNL] set root filesystem mount option string
566 rootfstype= [KNL] set root filesystem type
568 rw [KNL] Mount root device read-write on boot.
570 S [KNL] run init in single mode.
574 sbpcd= [HW,CD] Soundblaster CD adapter.
580 sg_def_reserved_size=
591 sonicvibes= [HW,SOUND]
597 soundmodem= [HW,AX25,SOUND] Use sound card as packet radio modem.
599 specialix= [HW,SERIAL] Specialix multi-serial port adapter.
603 st= [HW,SCSI] SCSI tape parameters (buffers, etc.).
609 swiotlb= [IA-64] Number of I/O TLB slabs.
643 video= [FB] frame buffer configuration.
645 vga= [BOOT] on ix386, select a particular video mode
646 (use vga=ask for menu). This is actually a
647 boot loader parameter; the value is passed to
648 the kernel using a special protocol. See
649 linux/Documentation/i386/boot.txt for information.
655 waveartist= [HW,SOUND]
663 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.