1July 2000 Kernel Parameters v2.4.0 2 ~~~~~~~~~~~~~~~~~ 3 4The following is a consolidated list of the kernel parameters as implemented 5by the __setup() macro and sorted into English Dictionary order (defined 6as ignoring all punctuation and sorting digits before letters in a case 7insensitive manner), and with descriptions where known. 8 9The text in square brackets at the beginning of the description state the 10restrictions on the kernel for the said kernel parameter to be valid. The 11restrictions 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 ISAPNP ISA PnP code is enabled. 27 ISDN Appropriate ISDN support is enabled. 28 JOY Appropriate joystick support is enabled. 29 LP Printer support is enabled. 30 LOOP Loopback device support is enabled. 31 M68k M68k architecture is enabled. 32 MCA MCA bus support is enabled. 33 MDA MDA console support is enabled. 34 MOUSE Appropriate mouse support is enabled. 35 NET Appropriate network support is enabled. 36 NFS Appropriate NFS support is enabled. 37 PARIDE The ParIDE subsystem is enabled. 38 PCI PCI bus support is enabled. 39 PCMCIA The PCMCIA subsystem is enabled. 40 PNP Plug & Play support is enabled. 41 PPT Parallel port support is enabled. 42 PS2 Appropriate PS/2 support is enabled. 43 RAM RAM disk support is enabled. 44 SCSI Appropriate SCSI support is enabled. 45 SERIAL Serial support is enabled. 46 SMP The kernel is an SMP kernel. 47 SOUND Appropriate sound system support is enabled. 48 V4L Video For Linux support is enabled. 49 VGA The VGA console has been enabled. 50 VT Virtual terminal support is enabled. 51 XT IBM PC/XT MFM hard disk support is enabled. 52 53In addition, the following text indicates that the option: 54 55 BUGS= Relates to possible processor bugs on the said processor. 56 KNL Is a kernel start-up parameter. 57 BOOT Is a boot loader parameter. 58 59Parameters denoted with BOOT are actually interpreted by the boot 60loader, and have no meaning to the kernel directly. 61 62Note that ALL kernel parameters listed below are CASE SENSITIVE, and that 63a trailing = on the name of any parameter states that that parameter will 64be entered as an environment variable, whereas its absence indicates that 65it will appear as a kernel argument readable via /proc/cmdline by programs 66running once the system is up. 67 68 53c7xx= [HW,SCSI] Amiga SCSI controllers. 69 70 acpi= [HW,ACPI] Advanced Configuration and Power Interface 71 72 ad1816= [HW,SOUND] 73 74 ad1848= [HW,SOUND] 75 76 adb_buttons= [HW,MOUSE] 77 78 adlib= [HW,SOUND] 79 80 advansys= [HW,SCSI] 81 82 aedsp16= [HW,SOUND] 83 84 aha152x= [HW,SCSI] 85 86 aha1542= [HW,SCSI] 87 88 aic7xxx= [HW,SCSI] 89 90 AM53C974= [HW,SCSI] 91 92 amijoy= [HW,JOY] Amiga joystick support 93 94 apm= [APM] Advanced Power Management. 95 96 applicom= [HW] 97 98 arcrimi= [HW,NET] 99 100 ataflop= [HW,M68k] 101 102 atarimouse= [HW,MOUSE] Atari Mouse. 103 104 atascsi= [HW,SCSI] Atari SCSI. 105 106 awe= [HW,SOUND] 107 108 aztcd= [HW,CD] Aztec CD driver. 109 110 baycom_epp= [HW,AX25] 111 112 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem. 113 114 baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Full 115 Duplex Mode. 116 117 baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Half 118 Duplex Mode. 119 120 bmouse= [HW,MOUSE,PS2] Bus mouse. 121 122 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards), most 123 bttv.radio= important insmod options are available as kernel args too. 124 bttv.pll= see Documentation/video4linux/bttv/Insmod-options 125 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST 126 127 BusLogic= [HW,SCSI] 128 129 cdu31a= [HW,CD] 130 131 chandev= [HW,NET] 132 133 cm206= [HW,CD] 134 135 com20020= [HW,NET] 136 137 com90io= [HW,NET] 138 139 com90xx= [HW,NET] 140 141 condev= [HW] 142 143 console= [KNL] output console + comm spec (speed, control, 144 parity). 145 146 cpia_pp= [HW,PPT] 147 148 cs4232= [HW,SOUND] 149 150 cs89x0_dma= [HW,NET] 151 152 ctc= [HW,NET] 153 154 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter. 155 156 dasd= [HW,NET] 157 158 db9= [HW,JOY] 159 160 db9_2= [HW,JOY] 161 162 db9_3= [HW,JOY] 163 164 debug [KNL] Enable kernel debugging (events log level). 165 166 decnet= [HW,NET] 167 168 devfs= [DEVFS] 169 170 digi= [HW,SERIAL] io parameters + enable/disable command. 171 172 digiepca= [HW,SERIAL] 173 174 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA 175 support available. 176 177 dmasound= [HW,SOUND] (sound subsystem buffers). 178 179 dtc3181e= [HW,SCSI] 180 181 eata= [HW,SCSI] 182 183 eda= [HW,PS2] 184 185 edb= [HW,PS2] 186 187 eicon= [HW,ISDN] 188 189 es1370= [HW,SOUND] 190 191 es1371= [HW,SOUND] 192 193 ether= [HW,NET] Ethernet cards parameters (irq, 194 base_io_addr, mem_start, mem_end, name. 195 (mem_start is often overloaded to mean something 196 different and driver-specific). 197 198 fd_mcs= [HW,SCSI] 199 200 fdomain= [HW,SCSI] 201 202 floppy= [HW] 203 204 ftape= [HW] Floppy Tape subsystem debugging options. 205 206 gamma= [HW,DRM] 207 208 gc= [HW,JOY] 209 210 gc_2= [HW,JOY] 211 212 gc_3= [HW,JOY] 213 214 gdth= [HW,SCSI] 215 216 gpt [EFI] Forces disk with valid GPT signature but 217 invalid Protective MBR to be treated as GPT. 218 219 gscd= [HW,CD] 220 221 gus= [HW,SOUND] 222 223 gvp11= [HW,SCSI] 224 225 hd= [EIDE] (E)IDE hard drive subsystem geometry 226 (Cyl/heads/sectors) or tune parameters. 227 228 hfmodem= [HW,AX25] 229 230 hisax= [HW,ISDN] 231 232 i810= [HW,DRM] 233 234 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter. 235 236 icn= [HW,ISDN] 237 238 ide?= [HW] (E)IDE subsystem : config (iomem/irq), tuning or 239 debugging (serialize,reset,no{dma,tune,probe}) or 240 chipset specific parameters. 241 242 idebus= [HW] (E)IDE subsystem : VLB/PCI bus speed. 243 244 idle= [HW] 245 246 in2000= [HW,SCSI] 247 248 init= [KNL] 249 250 initrd= [BOOT] Specify the location of the initial ramdisk. 251 252 ip= [PNP] 253 254 isapnp= [ISAPNP] Specify RDP, reset, pci_scan and verbosity. 255 256 isapnp_reserve_irq= [ISAPNP] Exclude IRQs for the autoconfiguration. 257 258 isapnp_reserve_dma= [ISAPNP] Exclude DMAs for the autoconfiguration. 259 260 isapnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration. 261 Ranges are in pairs (I/O port base and size). 262 263 isapnp_reserve_mem= [ISAPNP] Exclude memory regions for the autoconfiguration. 264 Ranges are in pairs (memory base and size). 265 266 isp16= [HW,CD] 267 268 iucv= [HW,NET] 269 270 js= [HW,JOY] Analog joystick 271 272 kbd-reset [VT] 273 274 keep_initrd [HW, ARM] 275 276 load_ramdisk= [RAM] List of ramdisks to load from floppy. 277 278 logi_busmouse= [HW, MOUSE] 279 280 lp=0 [LP] Specify parallel ports to use, e.g, 281 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 282 lp=reset first parallel port). 'lp=0' disables the 283 lp=auto printer driver. 'lp=reset' (which can be 284 specified in addition to the ports) causes 285 attached printers to be reset. Using 286 lp=port1,port2,... specifies the parallel ports 287 to associate lp devices with, starting with 288 lp0. A port specification may be 'none' to skip 289 that lp device, or a parport name such as 290 'parport0'. Specifying 'lp=auto' instead of a 291 port specification list means that device IDs 292 from each port should be examined, to see if 293 an IEEE 1284-compliant printer is attached; if 294 so, the driver will manage that printer. 295 296 ltpc= [HW] 297 298 mac5380= [HW,SCSI] 299 300 mac53c9x= [HW,SCSI] 301 302 mad16= [HW,SOUND] 303 304 maui= [HW,SOUND] 305 306 max_loop=[0-255] [LOOP] Set the maximum number of loopback devices 307 that can be mounted. 308 309 maxcpus= [SMP] States the maximum number of processors that 310 an SMP kernel should make use of. 311 312 max_scsi_luns= [SCSI] 313 314 mca-pentium [BUGS=ix86] 315 316 mcd= [HW,CD] 317 318 mcdx= [HW,CD] 319 320 md= [HW] RAID subsystems devices and level. 321 322 mdisk= [HW] 323 324 mdacon= [MDA] 325 326 megaraid= [HW,SCSI] 327 328 mem=nn[KMG] [KNL,BOOT] force use of a specific amount of 329 memory; to be used when the kernel is not able 330 to see the whole system memory or for test. 331 332 memfrac= [KNL] 333 334 mga= [HW,DRM] 335 336 mpu401= [HW,SOUND] 337 338 msmouse= [HW,MOUSE] Microsoft Mouse. 339 340 ncr5380= [HW,SCSI] 341 342 ncr53c400= [HW,SCSI] 343 344 ncr53c400a= [HW,SCSI] 345 346 ncr53c406a= [HW,SCSI] 347 348 ncr53c8xx= [HW,SCSI] 349 350 netdev= [NET] Ethernet cards parameters (irq, 351 base_io_addr, mem_start, mem_end, name. 352 (mem_start is often overloaded to mean something 353 different and driver-specific). 354 (cf: ether=) 355 356 nfsaddrs= [NFS] 357 358 nfsroot= [NFS] nfs root filesystem for disk-less boxes. 359 360 nmi_watchdog= [KNL,BUGS=ix86] debugging features for SMP kernels. 361 362 no387 [BUGS=ix86] Tells the kernel to use the 387 maths 363 emulation library even if a 387 maths coprocessor 364 is present. 365 366 noalign [KNL,ARM] 367 368 noapic [SMP,APIC] Tells the kernel not to make use of any 369 APIC that may be present on the system. 370 371 noasync [HW, M68K] Disables async and sync negotiation for 372 all devices. 373 374 nocache [ARM] 375 376 nodisconnect [HW,SCSI, M68K] Disables SCSI disconnects. 377 378 nohlt [BUGS=ARM] 379 380 no-hlt [BUGS=ix86] 381 382 noisapnp [ISAPNP] Disables ISA PnP code. 383 384 noinitrd [RAM] Tells the kernel not to load any configured 385 initial RAM disk. 386 387 nointroute [IA-64] 388 389 no-scroll [VGA] 390 391 nosmp [SMP] Tells an SMP kernel to act as a UP kernel. 392 393 nosync [HW, M68K] Disables sync negotiation for all devices. 394 395 notsc [BUGS=ix86] Disable Time Stamp Counter 396 397 nowb [ARM] 398 399 opl3= [HW,SOUND] 400 401 opl3sa= [HW,SOUND] 402 403 opl3sa2= [HW,SOUND] 404 405 optcd= [HW,CD] 406 407 panic= [KNL] kernel behaviour on panic. 408 409 parport=0 [HW,PPT] Specify parallel ports. 0 disables. 410 parport=auto Use 'auto' to force the driver to use 411 parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the 412 default is to ignore detected IRQ/DMA 413 settings because of possible 414 conflicts). You can specify the base 415 address, IRQ, and DMA settings; IRQ and 416 DMA should be numbers, or 'auto' (for 417 using detected settings on that 418 particular port), or 'nofifo' (to avoid 419 using a FIFO even if it is detected). 420 Parallel ports are assigned in the 421 order they are specified on the command 422 line, starting with parport0. 423 424 pas2= [HW,SOUND] 425 426 pas16= [HW,SCSI] 427 428 pcbit= [HW,ISDN] 429 430 pcd. [PARIDE] 431 432 pci=option[,option...] [PCI] various PCI subsystem options: 433 off [IA-32] don't probe for the PCI bus 434 bios [IA-32] force use of PCI BIOS, don't access 435 the hardware directly. Use this if your machine 436 has a non-standard PCI host bridge. 437 nobios [IA-32] disallow use of PCI BIOS, only direct 438 hardware access methods are allowed. Use this 439 if you experience crashes upon bootup and you 440 suspect they are caused by the BIOS. 441 conf1 [IA-32] Force use of PCI Configuration Mechanism 1. 442 conf2 [IA-32] Force use of PCI Configuration Mechanism 2. 443 nosort [IA-32] Don't sort PCI devices according to 444 order given by the PCI BIOS. This sorting is done 445 to get a device order compatible with older kernels. 446 biosirq [IA-32] Use PCI BIOS calls to get the interrupt 447 routing table. These calls are known to be buggy 448 on several machines and they hang the machine when used, 449 but on other computers it's the only way to get the 450 interrupt routing table. Try this option if the kernel 451 is unable to allocate IRQs or discover secondary PCI 452 buses on your motherboard. 453 rom [IA-32] Assign address space to expansion ROMs. 454 Use with caution as certain devices share address 455 decoders between ROMs and other resources. 456 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be assigned 457 automatically to PCI devices. You can make the kernel 458 exclude IRQs of your ISA cards this way. 459 lastbus=N [IA-32] Scan all buses till bus #N. Can be useful 460 if the kernel is unable to find your secondary buses 461 and you want to tell it explicitly which ones they are. 462 assign-busses [IA-32] Always assign all PCI bus 463 numbers ourselves, overriding 464 whatever the firmware may have 465 done. 466 467 pd. [PARIDE] 468 469 pf. [PARIDE] 470 471 pg. [PARIDE] 472 473 pirq= [SMP,APIC] mp-table. 474 475 plip= [PPT,NET] Parallel port network link. 476 477 profile= [KNL] enable kernel profiling via /proc/profile 478 (param:log level). 479 480 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 481 before loading. 482 483 pss= [HW,SOUND] 484 485 pt. [PARIDE] 486 487 quiet= [KNL] Disable log messages. 488 489 r128= [HW,DRM] 490 491 raid= [HW,RAID] 492 493 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]. 494 495 ramdisk_blocksize= 496 [RAM] 497 498 ramdisk_size= [RAM] New name for the ramdisk parameter. 499 500 ramdisk_start= [RAM] Starting block of RAM disk image (so you can 501 place it after the kernel image on a boot floppy). 502 503 reboot= [BUGS=ix86] 504 505 reserve= [KNL,BUGS] force the kernel to ignore some iomem area. 506 507 riscom8= [HW,SERIAL] 508 509 ro [KNL] Mount root device read-only on boot. 510 511 root= [KNL] root filesystem. 512 513 rw [KNL] Mount root device read-write on boot. 514 515 S [KNL] run init in single mode. 516 517 sb= [HW,SOUND] 518 519 sbpcd= [HW,CD] Soundblaster CD adapter. 520 521 scsi_logging= [SCSI] 522 523 scsihosts= [SCSI] 524 525 sg_def_reserved_size= 526 [SCSI] 527 528 sgalaxy= [HW,SOUND] 529 530 sim710= [SCSI,HW] 531 532 sjcd= [HW,CD] 533 534 smart2= [HW] 535 536 sonicvibes= [HW,SOUND] 537 538 sonycd535= [HW,CD] 539 540 sound= [SOUND] 541 542 soundmodem= [HW,AX25,SOUND] Use sound card as packet radio modem. 543 544 specialix= [HW,SERIAL] Specialix multi-serial port adapter. 545 546 sscape= [HW,SOUND] 547 548 st= [HW,SCSI] SCSI tape parameters (buffers, etc.). 549 550 st0x= [HW,SCSI] 551 552 stram_swap= [HW] 553 554 swiotlb= [IA-64] Number of I/O TLB slabs. 555 556 switches= [HW, M68K] 557 558 sym53c416= [HW,SCSI] 559 560 sym53c8xx= [HW,SCSI] 561 562 t128= [HW,SCSI] 563 564 tdfx= [HW,DRM] 565 566 tgfx= [HW,JOY] 567 568 tgfx_2= [HW,JOY] 569 570 tgfx_3= [HW,JOY] 571 572 tmc8xx= [HW,SCSI] 573 574 tmscsim= [HW,SCSI] 575 576 tp720= [HW,PS2] 577 578 trix= [HW,SOUND] 579 580 u14-34f= [HW,SCSI] 581 582 uart401= [HW,SOUND] 583 584 uart6850= [HW,SOUND] 585 586 usbfix [BUGS=IA-64] 587 588 video= [FB] frame buffer configuration. 589 590 vga= [BOOT] on ix386, select a particular video mode 591 (use vga=ask for menu). This is actually a 592 boot loader parameter; the value is passed to 593 the kernel using a special protocol. See 594 linux/Documentation/i386/boot.txt for information. 595 596 vmhalt= [KNL,S390] 597 598 vmpoff= [KNL,S390] 599 600 waveartist= [HW,SOUND] 601 602 wd33c93= [HW,SCSI] 603 604 wd7000= [HW,SCSI] 605 606 wdt= [HW] 607 608 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. 609 610 xd_geo= [HW,XT] 611