1 July 2000 Kernel Parameters v2.4.0
2 ~~~~~~~~~~~~~~~~~
3
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.
8
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:
12
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.
53
54 In addition, the following text indicates that the option:
55
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.
59
60 Parameters denoted with BOOT are actually interpreted by the boot
61 loader, and have no meaning to the kernel directly.
62
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.
68
69 53c7xx= [HW,SCSI] Amiga SCSI controllers.
70
71 acpi= [HW,ACPI] Advanced Configuration and Power Interface
72 force Force ACPI on, even if blacklisted platform
73 off Disable ACPI
74 ht Limit ACPI to boot-time LAPIC enumeration for HT,
75 disabling the run-time AML interpreter.
76
77 ad1816= [HW,SOUND]
78
79 ad1848= [HW,SOUND]
80
81 adb_buttons= [HW,MOUSE]
82
83 adlib= [HW,SOUND]
84
85 advansys= [HW,SCSI]
86
87 aedsp16= [HW,SOUND]
88
89 aha152x= [HW,SCSI]
90
91 aha1542= [HW,SCSI]
92
93 aic7xxx= [HW,SCSI]
94
95 AM53C974= [HW,SCSI]
96
97 amijoy= [HW,JOY] Amiga joystick support
98
99 apm= [APM] Advanced Power Management.
100
101 applicom= [HW]
102
103 arcrimi= [HW,NET]
104
105 ataflop= [HW,M68k]
106
107 atarimouse= [HW,MOUSE] Atari Mouse.
108
109 atascsi= [HW,SCSI] Atari SCSI.
110
111 awe= [HW,SOUND]
112
113 aztcd= [HW,CD] Aztec CD driver.
114
115 baycom_epp= [HW,AX25]
116
117 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem.
118
119 baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Full
120 Duplex Mode.
121
122 baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Half
123 Duplex Mode.
124
125 bmouse= [HW,MOUSE,PS2] Bus mouse.
126
127 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards), most
128 bttv.radio= important insmod options are available as kernel args too.
129 bttv.pll= see Documentation/video4linux/bttv/Insmod-options
130 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
131
132 BusLogic= [HW,SCSI]
133
134 cdu31a= [HW,CD]
135
136 chandev= [HW,NET]
137
138 cm206= [HW,CD]
139
140 com20020= [HW,NET]
141
142 com90io= [HW,NET]
143
144 com90xx= [HW,NET]
145
146 condev= [HW]
147
148 console= [KNL] output console + comm spec (speed, control,
149 parity).
150
151 cpia_pp= [HW,PPT]
152
153 cs4232= [HW,SOUND]
154
155 cs89x0_dma= [HW,NET]
156
157 ctc= [HW,NET]
158
159 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
160
161 dasd= [HW,NET]
162
163 db9= [HW,JOY]
164
165 db9_2= [HW,JOY]
166
167 db9_3= [HW,JOY]
168
169 debug [KNL] Enable kernel debugging (events log level).
170
171 decnet= [HW,NET]
172
173 devfs= [DEVFS]
174
175 digi= [HW,SERIAL] io parameters + enable/disable command.
176
177 digiepca= [HW,SERIAL]
178
179 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
180 support available.
181
182 dmasound= [HW,SOUND] (sound subsystem buffers).
183
184 dtc3181e= [HW,SCSI]
185
186 eata= [HW,SCSI]
187
188 eda= [HW,PS2]
189
190 edb= [HW,PS2]
191
192 eicon= [HW,ISDN]
193
194 es1370= [HW,SOUND]
195
196 es1371= [HW,SOUND]
197
198 ether= [HW,NET] Ethernet cards parameters (irq,
199 base_io_addr, mem_start, mem_end, name.
200 (mem_start is often overloaded to mean something
201 different and driver-specific).
202
203 fd_mcs= [HW,SCSI]
204
205 fdomain= [HW,SCSI]
206
207 floppy= [HW]
208
209 ftape= [HW] Floppy Tape subsystem debugging options.
210
211 gamma= [HW,DRM]
212
213 gc= [HW,JOY]
214
215 gc_2= [HW,JOY]
216
217 gc_3= [HW,JOY]
218
219 gdth= [HW,SCSI]
220
221 gpt [EFI] Forces disk with valid GPT signature but
222 invalid Protective MBR to be treated as GPT.
223
224 gscd= [HW,CD]
225
226 gus= [HW,SOUND]
227
228 gvp11= [HW,SCSI]
229
230 hd= [EIDE] (E)IDE hard drive subsystem geometry
231 (Cyl/heads/sectors) or tune parameters.
232
233 hfmodem= [HW,AX25]
234
235 hisax= [HW,ISDN]
236
237 i810= [HW,DRM]
238
239 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter.
240
241 icn= [HW,ISDN]
242
243 ide?= [HW] (E)IDE subsystem : config (iomem/irq), tuning or
244 debugging (serialize,reset,no{dma,tune,probe}) or
245 chipset specific parameters.
246
247 idebus= [HW] (E)IDE subsystem : VLB/PCI bus speed.
248
249 idle= [HW]
250
251 in2000= [HW,SCSI]
252
253 init= [KNL]
254
255 initrd= [BOOT] Specify the location of the initial ramdisk.
256
257 ip= [IP_PNP]
258
259 isapnp= [ISAPNP] Specify RDP, reset, pci_scan and verbosity.
260
261 isapnp_reserve_irq= [ISAPNP] Exclude IRQs for the autoconfiguration.
262
263 isapnp_reserve_dma= [ISAPNP] Exclude DMAs for the autoconfiguration.
264
265 isapnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration.
266 Ranges are in pairs (I/O port base and size).
267
268 isapnp_reserve_mem= [ISAPNP] Exclude memory regions for the autoconfiguration.
269 Ranges are in pairs (memory base and size).
270
271 isp16= [HW,CD]
272
273 iucv= [HW,NET]
274
275 js= [HW,JOY] Analog joystick
276
277 kbd-reset [VT]
278
279 keepinitrd [HW, ARM]
280
281 load_ramdisk= [RAM] List of ramdisks to load from floppy.
282
283 lockd.udpport= [NFS]
284
285 lockd.tcpport= [NFS]
286
287 logi_busmouse= [HW, MOUSE]
288
289 lp=0 [LP] Specify parallel ports to use, e.g,
290 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
291 lp=reset first parallel port). 'lp=0' disables the
292 lp=auto printer driver. 'lp=reset' (which can be
293 specified in addition to the ports) causes
294 attached printers to be reset. Using
295 lp=port1,port2,... specifies the parallel ports
296 to associate lp devices with, starting with
297 lp0. A port specification may be 'none' to skip
298 that lp device, or a parport name such as
299 'parport0'. Specifying 'lp=auto' instead of a
300 port specification list means that device IDs
301 from each port should be examined, to see if
302 an IEEE 1284-compliant printer is attached; if
303 so, the driver will manage that printer.
304
305 ltpc= [HW]
306
307 mac5380= [HW,SCSI]
308
309 mac53c9x= [HW,SCSI]
310
311 mad16= [HW,SOUND]
312
313 maui= [HW,SOUND]
314
315 max_loop=[0-255] [LOOP] Set the maximum number of loopback devices
316 that can be mounted.
317
318 maxcpus= [SMP] States the maximum number of processors that
319 an SMP kernel should make use of.
320
321 max_scsi_luns= [SCSI]
322
323 mca-pentium [BUGS=IA-32]
324
325 mcd= [HW,CD]
326
327 mcdx= [HW,CD]
328
329 md= [HW] RAID subsystems devices and level.
330
331 mdisk= [HW]
332
333 mdacon= [MDA]
334
335 megaraid= [HW,SCSI]
336
337 mem=exactmap [KNL,BOOT,IA-32] enable setting of an exact
338 e820 memory map, as specified by the user.
339 Such mem=exactmap lines can be constructed
340 based on BIOS output or other requirements.
341
342 mem=nn[KMG] [KNL,BOOT] force use of a specific amount of
343 memory; to be used when the kernel is not able
344 to see the whole system memory or for test.
345
346 mem=nn[KMG]@ss[KMG]
347 [KNL,BOOT] Force usage of a specific region of memory
348 Region of memory to be used, from ss to ss+nn.
349
350 mem=nn[KMG]#ss[KMG]
351 [KNL,BOOT,ACPI] Mark specific memory as ACPI data.
352 Region of memory to be used, from ss to ss+nn.
353
354 mem=nn[KMG]$ss[KMG]
355 [KNL,BOOT,ACPI] Mark specific memory as reserved.
356 Region of memory to be used, from ss to ss+nn.
357
358 memfrac= [KNL]
359
360 mga= [HW,DRM]
361
362 mpu401= [HW,SOUND]
363
364 msmouse= [HW,MOUSE] Microsoft Mouse.
365
366 ncr5380= [HW,SCSI]
367
368 ncr53c400= [HW,SCSI]
369
370 ncr53c400a= [HW,SCSI]
371
372 ncr53c406a= [HW,SCSI]
373
374 ncr53c8xx= [HW,SCSI]
375
376 netdev= [NET] Ethernet cards parameters (irq,
377 base_io_addr, mem_start, mem_end, name.
378 (mem_start is often overloaded to mean something
379 different and driver-specific).
380 (cf: ether=)
381
382 nfsaddrs= [NFS]
383
384 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
385
386 nmi_watchdog= [KNL,BUGS=IA-32] debugging features for SMP kernels.
387
388 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
389 emulation library even if a 387 maths coprocessor
390 is present.
391
392 noalign [KNL,ARM]
393
394 noapic [SMP,APIC] Tells the kernel not to make use of any
395 APIC that may be present on the system.
396
397 noasync [HW, M68K] Disables async and sync negotiation for
398 all devices.
399
400 nocache [ARM]
401
402 nodisconnect [HW,SCSI, M68K] Disables SCSI disconnects.
403
404 nohlt [BUGS=ARM]
405
406 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
407 instruction doesn't work correctly and not to
408 use it.
409
410 noisapnp [ISAPNP] Disables ISA PnP code.
411
412 noinitrd [RAM] Tells the kernel not to load any configured
413 initial RAM disk.
414
415 nointroute [IA-64]
416
417 no-scroll [VGA]
418
419 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
420
421 nosync [HW, M68K] Disables sync negotiation for all devices.
422
423 notsc [BUGS=IA-32] Disable Time Stamp Counter
424
425 nowb [ARM]
426
427 opl3= [HW,SOUND]
428
429 opl3sa= [HW,SOUND]
430
431 opl3sa2= [HW,SOUND]
432
433 optcd= [HW,CD]
434
435 panic= [KNL] kernel behaviour on panic.
436
437 parport=0 [HW,PPT] Specify parallel ports. 0 disables.
438 parport=auto Use 'auto' to force the driver to use
439 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
440 default is to ignore detected IRQ/DMA
441 settings because of possible
442 conflicts). You can specify the base
443 address, IRQ, and DMA settings; IRQ and
444 DMA should be numbers, or 'auto' (for
445 using detected settings on that
446 particular port), or 'nofifo' (to avoid
447 using a FIFO even if it is detected).
448 Parallel ports are assigned in the
449 order they are specified on the command
450 line, starting with parport0.
451
452 pas2= [HW,SOUND]
453
454 pas16= [HW,SCSI]
455
456 pcbit= [HW,ISDN]
457
458 pcd. [PARIDE]
459
460 pci=option[,option...] [PCI] various PCI subsystem options:
461 off [IA-32] don't probe for the PCI bus
462 bios [IA-32] force use of PCI BIOS, don't access
463 the hardware directly. Use this if your machine
464 has a non-standard PCI host bridge.
465 nobios [IA-32] disallow use of PCI BIOS, only direct
466 hardware access methods are allowed. Use this
467 if you experience crashes upon bootup and you
468 suspect they are caused by the BIOS.
469 conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
470 conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
471 nosort [IA-32] Don't sort PCI devices according to
472 order given by the PCI BIOS. This sorting is done
473 to get a device order compatible with older kernels.
474 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
475 routing table. These calls are known to be buggy
476 on several machines and they hang the machine when used,
477 but on other computers it's the only way to get the
478 interrupt routing table. Try this option if the kernel
479 is unable to allocate IRQs or discover secondary PCI
480 buses on your motherboard.
481 rom [IA-32] Assign address space to expansion ROMs.
482 Use with caution as certain devices share address
483 decoders between ROMs and other resources.
484 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned
485 automatically to PCI devices. You can make the kernel
486 exclude IRQs of your ISA cards this way.
487 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
488 if the kernel is unable to find your secondary buses
489 and you want to tell it explicitly which ones they are.
490 assign-busses [IA-32] Always assign all PCI bus
491 numbers ourselves, overriding
492 whatever the firmware may have
493 done.
494
495 pd. [PARIDE]
496
497 pf. [PARIDE]
498
499 pg. [PARIDE]
500
501 pirq= [SMP,APIC] mp-table.
502
503 plip= [PPT,NET] Parallel port network link.
504
505 profile= [KNL] enable kernel profiling via /proc/profile
506 (param: profile step/bucket size as a power of 2)
507
508 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
509 before loading.
510
511 pss= [HW,SOUND]
512
513 pt. [PARIDE]
514
515 quiet= [KNL] Disable log messages.
516
517 r128= [HW,DRM]
518
519 raid= [HW,RAID]
520
521 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated].
522
523 ramdisk_blocksize=
524 [RAM]
525
526 ramdisk_size= [RAM] New name for the ramdisk parameter.
527
528 ramdisk_start= [RAM] Starting block of RAM disk image (so you can
529 place it after the kernel image on a boot floppy).
530
531 reboot= [BUGS=IA-32]
532
533 reserve= [KNL,BUGS] force the kernel to ignore some iomem area.
534
535 riscom8= [HW,SERIAL]
536
537 ro [KNL] Mount root device read-only on boot.
538
539 root= [KNL] root filesystem.
540
541 rootflags= [KNL] set root filesystem mount option string
542
543 rootfstype= [KNL] set root filesystem type
544
545 rw [KNL] Mount root device read-write on boot.
546
547 S [KNL] run init in single mode.
548
549 sb= [HW,SOUND]
550
551 sbpcd= [HW,CD] Soundblaster CD adapter.
552
553 scsi_logging= [SCSI]
554
555 scsihosts= [SCSI]
556
557 sg_def_reserved_size=
558 [SCSI]
559
560 sgalaxy= [HW,SOUND]
561
562 sim710= [SCSI,HW]
563
564 sjcd= [HW,CD]
565
566 smart2= [HW]
567
568 sonicvibes= [HW,SOUND]
569
570 sonycd535= [HW,CD]
571
572 sound= [SOUND]
573
574 soundmodem= [HW,AX25,SOUND] Use sound card as packet radio modem.
575
576 specialix= [HW,SERIAL] Specialix multi-serial port adapter.
577
578 sscape= [HW,SOUND]
579
580 st= [HW,SCSI] SCSI tape parameters (buffers, etc.).
581
582 st0x= [HW,SCSI]
583
584 stram_swap= [HW]
585
586 swiotlb= [IA-64] Number of I/O TLB slabs.
587
588 switches= [HW, M68K]
589
590 sym53c416= [HW,SCSI]
591
592 sym53c8xx= [HW,SCSI]
593
594 t128= [HW,SCSI]
595
596 tdfx= [HW,DRM]
597
598 tgfx= [HW,JOY]
599
600 tgfx_2= [HW,JOY]
601
602 tgfx_3= [HW,JOY]
603
604 tmc8xx= [HW,SCSI]
605
606 tmscsim= [HW,SCSI]
607
608 tp720= [HW,PS2]
609
610 trix= [HW,SOUND]
611
612 u14-34f= [HW,SCSI]
613
614 uart401= [HW,SOUND]
615
616 uart6850= [HW,SOUND]
617
618 usbfix [BUGS=IA-64]
619
620 video= [FB] frame buffer configuration.
621
622 vga= [BOOT] on ix386, select a particular video mode
623 (use vga=ask for menu). This is actually a
624 boot loader parameter; the value is passed to
625 the kernel using a special protocol. See
626 linux/Documentation/i386/boot.txt for information.
627
628 vmhalt= [KNL,S390]
629
630 vmpoff= [KNL,S390]
631
632 waveartist= [HW,SOUND]
633
634 wd33c93= [HW,SCSI]
635
636 wd7000= [HW,SCSI]
637
638 wdt= [HW]
639
640 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
641
642 xd_geo= [HW,XT]
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