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
73 acpismp=force [IA-32] Early setup parse and use ACPI SMP table.
79 adb_buttons= [HW,MOUSE]
95 amijoy= [HW,JOY] Amiga joystick support
97 apm= [APM] Advanced Power Management.
105 atarimouse= [HW,MOUSE] Atari Mouse.
107 atascsi= [HW,SCSI] Atari SCSI.
111 aztcd= [HW,CD] Aztec CD driver.
113 baycom_epp= [HW,AX25]
115 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem.
117 baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Full
120 baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Half
123 bmouse= [HW,MOUSE,PS2] Bus mouse.
125 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards), most
126 bttv.radio= important insmod options are available as kernel args too.
127 bttv.pll= see Documentation/video4linux/bttv/Insmod-options
128 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
146 console= [KNL] output console + comm spec (speed, control,
157 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
167 debug [KNL] Enable kernel debugging (events log level).
173 digi= [HW,SERIAL] io parameters + enable/disable command.
175 digiepca= [HW,SERIAL]
177 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
180 dmasound= [HW,SOUND] (sound subsystem buffers).
196 ether= [HW,NET] Ethernet cards parameters (irq,
197 base_io_addr, mem_start, mem_end, name.
198 (mem_start is often overloaded to mean something
199 different and driver-specific).
207 ftape= [HW] Floppy Tape subsystem debugging options.
219 gpt [EFI] Forces disk with valid GPT signature but
220 invalid Protective MBR to be treated as GPT.
228 hd= [EIDE] (E)IDE hard drive subsystem geometry
229 (Cyl/heads/sectors) or tune parameters.
237 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter.
241 ide?= [HW] (E)IDE subsystem : config (iomem/irq), tuning or
242 debugging (serialize,reset,no{dma,tune,probe}) or
243 chipset specific parameters.
245 idebus= [HW] (E)IDE subsystem : VLB/PCI bus speed.
253 initrd= [BOOT] Specify the location of the initial ramdisk.
257 isapnp= [ISAPNP] Specify RDP, reset, pci_scan and verbosity.
259 isapnp_reserve_irq= [ISAPNP] Exclude IRQs for the autoconfiguration.
261 isapnp_reserve_dma= [ISAPNP] Exclude DMAs for the autoconfiguration.
263 isapnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration.
264 Ranges are in pairs (I/O port base and size).
266 isapnp_reserve_mem= [ISAPNP] Exclude memory regions for the autoconfiguration.
267 Ranges are in pairs (memory base and size).
273 js= [HW,JOY] Analog joystick
279 load_ramdisk= [RAM] List of ramdisks to load from floppy.
285 logi_busmouse= [HW, MOUSE]
287 lp=0 [LP] Specify parallel ports to use, e.g,
288 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
289 lp=reset first parallel port). 'lp=0' disables the
290 lp=auto printer driver. 'lp=reset' (which can be
291 specified in addition to the ports) causes
292 attached printers to be reset. Using
293 lp=port1,port2,... specifies the parallel ports
294 to associate lp devices with, starting with
295 lp0. A port specification may be 'none' to skip
296 that lp device, or a parport name such as
297 'parport0'. Specifying 'lp=auto' instead of a
298 port specification list means that device IDs
299 from each port should be examined, to see if
300 an IEEE 1284-compliant printer is attached; if
301 so, the driver will manage that printer.
313 max_loop=[0-255] [LOOP] Set the maximum number of loopback devices
316 maxcpus= [SMP] States the maximum number of processors that
317 an SMP kernel should make use of.
319 max_scsi_luns= [SCSI]
321 mca-pentium [BUGS=IA-32]
327 md= [HW] RAID subsystems devices and level.
335 mem=exactmap [KNL,BOOT,IA-32] enable setting of an exact
336 e820 memory map, as specified by the user.
337 Such mem=exactmap lines can be constructed
338 based on BIOS output or other requirements.
340 mem=nn[KMG] [KNL,BOOT] force use of a specific amount of
341 memory; to be used when the kernel is not able
342 to see the whole system memory or for test.
350 msmouse= [HW,MOUSE] Microsoft Mouse.
356 ncr53c400a= [HW,SCSI]
358 ncr53c406a= [HW,SCSI]
362 netdev= [NET] Ethernet cards parameters (irq,
363 base_io_addr, mem_start, mem_end, name.
364 (mem_start is often overloaded to mean something
365 different and driver-specific).
370 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
372 nmi_watchdog= [KNL,BUGS=IA-32] debugging features for SMP kernels.
374 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
375 emulation library even if a 387 maths coprocessor
380 noapic [SMP,APIC] Tells the kernel not to make use of any
381 APIC that may be present on the system.
383 noasync [HW, M68K] Disables async and sync negotiation for
388 nodisconnect [HW,SCSI, M68K] Disables SCSI disconnects.
392 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
393 instruction doesn't work correctly and not to
396 noht [SMP,IA-32] Disables P4 Xeon(tm) HyperThreading.
398 noisapnp [ISAPNP] Disables ISA PnP code.
400 noinitrd [RAM] Tells the kernel not to load any configured
407 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
409 nosync [HW, M68K] Disables sync negotiation for all devices.
411 notsc [BUGS=IA-32] Disable Time Stamp Counter
423 panic= [KNL] kernel behaviour on panic.
425 parport=0 [HW,PPT] Specify parallel ports. 0 disables.
426 parport=auto Use 'auto' to force the driver to use
427 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
428 default is to ignore detected IRQ/DMA
429 settings because of possible
430 conflicts). You can specify the base
431 address, IRQ, and DMA settings; IRQ and
432 DMA should be numbers, or 'auto' (for
433 using detected settings on that
434 particular port), or 'nofifo' (to avoid
435 using a FIFO even if it is detected).
436 Parallel ports are assigned in the
437 order they are specified on the command
438 line, starting with parport0.
448 pci=option[,option...] [PCI] various PCI subsystem options:
449 off [IA-32] don't probe for the PCI bus
450 bios [IA-32] force use of PCI BIOS, don't access
451 the hardware directly. Use this if your machine
452 has a non-standard PCI host bridge.
453 nobios [IA-32] disallow use of PCI BIOS, only direct
454 hardware access methods are allowed. Use this
455 if you experience crashes upon bootup and you
456 suspect they are caused by the BIOS.
457 conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
458 conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
459 nosort [IA-32] Don't sort PCI devices according to
460 order given by the PCI BIOS. This sorting is done
461 to get a device order compatible with older kernels.
462 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
463 routing table. These calls are known to be buggy
464 on several machines and they hang the machine when used,
465 but on other computers it's the only way to get the
466 interrupt routing table. Try this option if the kernel
467 is unable to allocate IRQs or discover secondary PCI
468 buses on your motherboard.
469 rom [IA-32] Assign address space to expansion ROMs.
470 Use with caution as certain devices share address
471 decoders between ROMs and other resources.
472 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned
473 automatically to PCI devices. You can make the kernel
474 exclude IRQs of your ISA cards this way.
475 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
476 if the kernel is unable to find your secondary buses
477 and you want to tell it explicitly which ones they are.
478 assign-busses [IA-32] Always assign all PCI bus
479 numbers ourselves, overriding
480 whatever the firmware may have
489 pirq= [SMP,APIC] mp-table.
491 plip= [PPT,NET] Parallel port network link.
493 profile= [KNL] enable kernel profiling via /proc/profile
496 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
503 quiet= [KNL] Disable log messages.
509 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated].
514 ramdisk_size= [RAM] New name for the ramdisk parameter.
516 ramdisk_start= [RAM] Starting block of RAM disk image (so you can
517 place it after the kernel image on a boot floppy).
521 reserve= [KNL,BUGS] force the kernel to ignore some iomem area.
525 ro [KNL] Mount root device read-only on boot.
527 root= [KNL] root filesystem.
529 rootflags= [KNL] set root filesystem mount option string
531 rootfstype= [KNL] set root filesystem type
533 rw [KNL] Mount root device read-write on boot.
535 S [KNL] run init in single mode.
539 sbpcd= [HW,CD] Soundblaster CD adapter.
545 sg_def_reserved_size=
556 sonicvibes= [HW,SOUND]
562 soundmodem= [HW,AX25,SOUND] Use sound card as packet radio modem.
564 specialix= [HW,SERIAL] Specialix multi-serial port adapter.
568 st= [HW,SCSI] SCSI tape parameters (buffers, etc.).
574 swiotlb= [IA-64] Number of I/O TLB slabs.
608 video= [FB] frame buffer configuration.
610 vga= [BOOT] on ix386, select a particular video mode
611 (use vga=ask for menu). This is actually a
612 boot loader parameter; the value is passed to
613 the kernel using a special protocol. See
614 linux/Documentation/i386/boot.txt for information.
620 waveartist= [HW,SOUND]
628 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.