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1 Kernel Parameters 2 ~~~~~~~~~~~~~~~~~ 3 4The 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 7case insensitive manner), and with descriptions where known. 8 9Module parameters for loadable modules are specified only as the 10parameter name with optional '=' and value as appropriate, such as: 11 12 modprobe usbcore blinkenlights=1 13 14Module parameters for modules that are built into the kernel image 15are specified on the kernel command line with the module name plus 16'.' plus parameter name, with '=' and value if appropriate, such as: 17 18 usbcore.blinkenlights=1 19 20This document may not be entirely up to date and comprehensive. The command 21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable 22module. Loadable modules, after being loaded into the running kernel, also 23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these 24parameters may be changed at runtime by the command 25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}". 26 27The parameters listed below are only valid if certain kernel build options were 28enabled and if respective hardware is present. The text in square brackets at 29the beginning of each description states the restrictions within which a 30parameter is applicable: 31 32 ACPI ACPI support is enabled. 33 ALSA ALSA sound support is enabled. 34 APIC APIC support is enabled. 35 APM Advanced Power Management support is enabled. 36 AX25 Appropriate AX.25 support is enabled. 37 CD Appropriate CD support is enabled. 38 DRM Direct Rendering Management support is enabled. 39 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled 40 EFI EFI Partitioning (GPT) is enabled 41 EIDE EIDE/ATAPI support is enabled. 42 FB The frame buffer device is enabled. 43 HW Appropriate hardware is enabled. 44 IA-32 IA-32 aka i386 architecture is enabled. 45 IA-64 IA-64 architecture is enabled. 46 IOSCHED More than one I/O scheduler is enabled. 47 IP_PNP IP DHCP, BOOTP, or RARP is enabled. 48 ISAPNP ISA PnP code is enabled. 49 ISDN Appropriate ISDN support is enabled. 50 JOY Appropriate joystick support is enabled. 51 LP Printer support is enabled. 52 LOOP Loopback device support is enabled. 53 M68k M68k architecture is enabled. 54 These options have more detailed description inside of 55 Documentation/m68k/kernel-options.txt. 56 MCA MCA bus support is enabled. 57 MDA MDA console support is enabled. 58 MOUSE Appropriate mouse support is enabled. 59 MSI Message Signaled Interrupts (PCI). 60 MTD MTD support is enabled. 61 NET Appropriate network support is enabled. 62 NUMA NUMA support is enabled. 63 GENERIC_TIME The generic timeofday code is enabled. 64 NFS Appropriate NFS support is enabled. 65 OSS OSS sound support is enabled. 66 PARIDE The ParIDE subsystem is enabled. 67 PARISC The PA-RISC architecture is enabled. 68 PCI PCI bus support is enabled. 69 PCMCIA The PCMCIA subsystem is enabled. 70 PNP Plug & Play support is enabled. 71 PPC PowerPC architecture is enabled. 72 PPT Parallel port support is enabled. 73 PS2 Appropriate PS/2 support is enabled. 74 RAM RAM disk support is enabled. 75 S390 S390 architecture is enabled. 76 SCSI Appropriate SCSI support is enabled. 77 A lot of drivers has their options described inside of 78 Documentation/scsi/. 79 SELINUX SELinux support is enabled. 80 SERIAL Serial support is enabled. 81 SMP The kernel is an SMP kernel. 82 SPARC Sparc architecture is enabled. 83 SWSUSP Software suspend is enabled. 84 TS Appropriate touchscreen support is enabled. 85 USB USB support is enabled. 86 USBHID USB Human Interface Device support is enabled. 87 V4L Video For Linux support is enabled. 88 VGA The VGA console has been enabled. 89 VT Virtual terminal support is enabled. 90 WDT Watchdog support is enabled. 91 XT IBM PC/XT MFM hard disk support is enabled. 92 X86-64 X86-64 architecture is enabled. 93 More X86-64 boot options can be found in 94 Documentation/x86_64/boot-options.txt . 95 96In addition, the following text indicates that the option: 97 98 BUGS= Relates to possible processor bugs on the said processor. 99 KNL Is a kernel start-up parameter. 100 BOOT Is a boot loader parameter. 101 102Parameters denoted with BOOT are actually interpreted by the boot 103loader, and have no meaning to the kernel directly. 104Do not modify the syntax of boot loader parameters without extreme 105need or coordination with <Documentation/i386/boot.txt>. 106 107Note that ALL kernel parameters listed below are CASE SENSITIVE, and that 108a trailing = on the name of any parameter states that that parameter will 109be entered as an environment variable, whereas its absence indicates that 110it will appear as a kernel argument readable via /proc/cmdline by programs 111running once the system is up. 112 113The number of kernel parameters is not limited, but the length of the 114complete command line (parameters including spaces etc.) is limited to 115a fixed number of characters. This limit depends on the architecture 116and is between 256 and 4096 characters. It is defined in the file 117./include/asm/setup.h as COMMAND_LINE_SIZE. 118 119 120 53c7xx= [HW,SCSI] Amiga SCSI controllers 121 See header of drivers/scsi/53c7xx.c. 122 See also Documentation/scsi/ncr53c7xx.txt. 123 124 acpi= [HW,ACPI] Advanced Configuration and Power Interface 125 Format: { force | off | ht | strict | noirq } 126 force -- enable ACPI if default was off 127 off -- disable ACPI if default was on 128 noirq -- do not use ACPI for IRQ routing 129 ht -- run only enough ACPI to enable Hyper Threading 130 strict -- Be less tolerant of platforms that are not 131 strictly ACPI specification compliant. 132 133 See also Documentation/pm.txt, pci=noacpi 134 135 acpi_sleep= [HW,ACPI] Sleep options 136 Format: { s3_bios, s3_mode } 137 See Documentation/power/video.txt 138 139 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode 140 Format: { level | edge | high | low } 141 142 acpi_irq_balance [HW,ACPI] 143 ACPI will balance active IRQs 144 default in APIC mode 145 146 acpi_irq_nobalance [HW,ACPI] 147 ACPI will not move active IRQs (default) 148 default in PIC mode 149 150 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for 151 use by PCI 152 Format: <irq>,<irq>... 153 154 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA 155 Format: <irq>,<irq>... 156 157 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 158 Format: To spoof as Windows 98: ="Microsoft Windows" 159 160 acpi_osi= [HW,ACPI] empty param disables _OSI 161 162 acpi_serialize [HW,ACPI] force serialization of AML methods 163 164 acpi_skip_timer_override [HW,ACPI] 165 Recognize and ignore IRQ0/pin2 Interrupt Override. 166 For broken nForce2 BIOS resulting in XT-PIC timer. 167 168 acpi_dbg_layer= [HW,ACPI] 169 Format: <int> 170 Each bit of the <int> indicates an ACPI debug layer, 171 1: enable, 0: disable. It is useful for boot time 172 debugging. After system has booted up, it can be set 173 via /proc/acpi/debug_layer. 174 175 acpi_dbg_level= [HW,ACPI] 176 Format: <int> 177 Each bit of the <int> indicates an ACPI debug level, 178 1: enable, 0: disable. It is useful for boot time 179 debugging. After system has booted up, it can be set 180 via /proc/acpi/debug_level. 181 182 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT 183 184 acpi_generic_hotkey [HW,ACPI] 185 Allow consolidated generic hotkey driver to 186 override platform specific driver. 187 See also Documentation/acpi-hotkey.txt. 188 189 acpi_pm_good [IA-32,X86-64] 190 Override the pmtimer bug detection: force the kernel 191 to assume that this machine's pmtimer latches its value 192 and always returns good values. 193 194 enable_timer_pin_1 [i386,x86-64] 195 Enable PIN 1 of APIC timer 196 Can be useful to work around chipset bugs 197 (in particular on some ATI chipsets). 198 The kernel tries to set a reasonable default. 199 200 disable_timer_pin_1 [i386,x86-64] 201 Disable PIN 1 of APIC timer 202 Can be useful to work around chipset bugs. 203 204 ad1816= [HW,OSS] 205 Format: <io>,<irq>,<dma>,<dma2> 206 See also Documentation/sound/oss/AD1816. 207 208 ad1848= [HW,OSS] 209 Format: <io>,<irq>,<dma>,<dma2>,<type> 210 211 adlib= [HW,OSS] 212 Format: <io> 213 214 advansys= [HW,SCSI] 215 See header of drivers/scsi/advansys.c. 216 217 advwdt= [HW,WDT] Advantech WDT 218 Format: <iostart>,<iostop> 219 220 aedsp16= [HW,OSS] Audio Excel DSP 16 221 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq> 222 See also header of sound/oss/aedsp16.c. 223 224 aha152x= [HW,SCSI] 225 See Documentation/scsi/aha152x.txt. 226 227 aha1542= [HW,SCSI] 228 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]] 229 230 aic7xxx= [HW,SCSI] 231 See Documentation/scsi/aic7xxx.txt. 232 233 aic79xx= [HW,SCSI] 234 See Documentation/scsi/aic79xx.txt. 235 236 amijoy.map= [HW,JOY] Amiga joystick support 237 Map of devices attached to JOY0DAT and JOY1DAT 238 Format: <a>,<b> 239 See also Documentation/kernel/input/joystick.txt 240 241 analog.map= [HW,JOY] Analog joystick and gamepad support 242 Specifies type or capabilities of an analog joystick 243 connected to one of 16 gameports 244 Format: <type1>,<type2>,..<type16> 245 246 apc= [HW,SPARC] 247 Power management functions (SPARCstation-4/5 + deriv.) 248 Format: noidle 249 Disable APC CPU standby support. SPARCstation-Fox does 250 not play well with APC CPU idle - disable it if you have 251 APC and your system crashes randomly. 252 253 apic= [APIC,i386] Change the output verbosity whilst booting 254 Format: { quiet (default) | verbose | debug } 255 Change the amount of debugging information output 256 when initialising the APIC and IO-APIC components. 257 258 apm= [APM] Advanced Power Management 259 See header of arch/i386/kernel/apm.c. 260 261 applicom= [HW] 262 Format: <mem>,<irq> 263 264 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards 265 Format: <io>,<irq>,<nodeID> 266 267 ataflop= [HW,M68k] 268 269 atarimouse= [HW,MOUSE] Atari Mouse 270 271 atascsi= [HW,SCSI] Atari SCSI 272 273 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, 274 EzKey and similar keyboards 275 276 atkbd.reset= [HW] Reset keyboard during initialization 277 278 atkbd.set= [HW] Select keyboard code set 279 Format: <int> (2 = AT (default), 3 = PS/2) 280 281 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar 282 keyboards 283 284 atkbd.softraw= [HW] Choose between synthetic and real raw mode 285 Format: <bool> (0 = real, 1 = synthetic (default)) 286 287 atkbd.softrepeat= [HW] 288 Use software keyboard repeat 289 290 autotest [IA64] 291 292 aztcd= [HW,CD] Aztech CD268 CDROM driver 293 Format: <io>,0x79 (?) 294 295 baycom_epp= [HW,AX25] 296 Format: <io>,<mode> 297 298 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem 299 Format: <io>,<mode> 300 See header of drivers/net/hamradio/baycom_par.c. 301 302 baycom_ser_fdx= [HW,AX25] 303 BayCom Serial Port AX.25 Modem (Full Duplex Mode) 304 Format: <io>,<irq>,<mode>[,<baud>] 305 See header of drivers/net/hamradio/baycom_ser_fdx.c. 306 307 baycom_ser_hdx= [HW,AX25] 308 BayCom Serial Port AX.25 Modem (Half Duplex Mode) 309 Format: <io>,<irq>,<mode> 310 See header of drivers/net/hamradio/baycom_ser_hdx.c. 311 312 blkmtd_device= [HW,MTD] 313 blkmtd_erasesz= 314 blkmtd_ro= 315 blkmtd_bs= 316 blkmtd_count= 317 318 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 319 bttv.radio= Most important insmod options are available as 320 kernel args too. 321 bttv.pll= See Documentation/video4linux/bttv/Insmod-options 322 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST 323 324 BusLogic= [HW,SCSI] 325 See drivers/scsi/BusLogic.c, comment before function 326 BusLogic_ParseDriverOptions(). 327 328 c101= [NET] Moxa C101 synchronous serial card 329 330 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection. 331 Sometimes CPU hardware bugs make them report the cache 332 size incorrectly. The kernel will attempt work arounds 333 to fix known problems, but for some CPUs it is not 334 possible to determine what the correct size should be. 335 This option provides an override for these situations. 336 337 cdu31a= [HW,CD] 338 Format: <io>,<irq>[,PAS] 339 See header of drivers/cdrom/cdu31a.c. 340 341 chandev= [HW,NET] Generic channel device initialisation 342 343 checkreqprot [SELINUX] Set initial checkreqprot flag value. 344 Format: { "0" | "1" } 345 See security/selinux/Kconfig help text. 346 0 -- check protection applied by kernel (includes 347 any implied execute protection). 348 1 -- check protection requested by application. 349 Default value is set via a kernel config option. 350 Value can be changed at runtime via 351 /selinux/checkreqprot. 352 353 clock= [BUGS=IA-32, HW] gettimeofday clocksource override. 354 [Deprecated] 355 Forces specified clocksource (if available) to be used 356 when calculating gettimeofday(). If specified 357 clocksource is not available, it defaults to PIT. 358 Format: { pit | tsc | cyclone | pmtmr } 359 360 disable_8254_timer 361 enable_8254_timer 362 [IA32/X86_64] Disable/Enable interrupt 0 timer routing 363 over the 8254 in addition to over the IO-APIC. The 364 kernel tries to set a sensible default. 365 366 hpet= [IA-32,HPET] option to disable HPET and use PIT. 367 Format: disable 368 369 cm206= [HW,CD] 370 Format: { auto | [<io>,][<irq>] } 371 372 com20020= [HW,NET] ARCnet - COM20020 chipset 373 Format: 374 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 375 376 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 377 Format: <io>[,<irq>] 378 379 com90xx= [HW,NET] 380 ARCnet - COM90xx chipset (memory-mapped buffers) 381 Format: <io>[,<irq>[,<memstart>]] 382 383 condev= [HW,S390] console device 384 conmode= 385 386 console= [KNL] Output console device and options. 387 388 tty<n> Use the virtual console device <n>. 389 390 ttyS<n>[,options] 391 ttyUSB0[,options] 392 Use the specified serial port. The options are of 393 the form "bbbbpnf", where "bbbb" is the baud rate, 394 "p" is parity ("n", "o", or "e"), "n" is number of 395 bits, and "f" is flow control ("r" for RTS or 396 omit it). Default is "9600n8". 397 398 See Documentation/serial-console.txt for more 399 information. See 400 Documentation/networking/netconsole.txt for an 401 alternative. 402 403 uart,io,<addr>[,options] 404 uart,mmio,<addr>[,options] 405 Start an early, polled-mode console on the 8250/16550 406 UART at the specified I/O port or MMIO address, 407 switching to the matching ttyS device later. The 408 options are the same as for ttyS, above. 409 410 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 411 Format: 412 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 413 414 cpia_pp= [HW,PPT] 415 Format: { parport<nr> | auto | none } 416 417 crashkernel=nn[KMG]@ss[KMG] 418 [KNL] Reserve a chunk of physical memory to 419 hold a kernel to switch to with kexec on panic. 420 421 cs4232= [HW,OSS] 422 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq> 423 424 cs89x0_dma= [HW,NET] 425 Format: <dma> 426 427 cs89x0_media= [HW,NET] 428 Format: { rj45 | aui | bnc } 429 430 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter. 431 432 dasd= [HW,NET] 433 See header of drivers/s390/block/dasd_devmap.c. 434 435 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 436 (one device per port) 437 Format: <port#>,<type> 438 See also Documentation/input/joystick-parport.txt 439 440 debug [KNL] Enable kernel debugging (events log level). 441 442 debug_locks_verbose= 443 [KNL] verbose self-tests 444 Format=<0|1> 445 Print debugging info while doing the locking API 446 self-tests. 447 We default to 0 (no extra messages), setting it to 448 1 will print _a lot_ more information - normally 449 only useful to kernel developers. 450 451 decnet= [HW,NET] 452 Format: <area>[,<node>] 453 See also Documentation/networking/decnet.txt. 454 455 dhash_entries= [KNL] 456 Set number of hash buckets for dentry cache. 457 458 digi= [HW,SERIAL] 459 IO parameters + enable/disable command. 460 461 digiepca= [HW,SERIAL] 462 See drivers/char/README.epca and 463 Documentation/digiepca.txt. 464 465 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA 466 support available. 467 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]] 468 469 dmasound= [HW,OSS] Sound subsystem buffers 470 471 dscc4.setup= [NET] 472 473 dtc3181e= [HW,SCSI] 474 475 earlyprintk= [IA-32,X86-64] 476 earlyprintk=vga 477 earlyprintk=serial[,ttySn[,baudrate]] 478 479 Append ",keep" to not disable it when the real console 480 takes over. 481 482 Only vga or serial at a time, not both. 483 484 Currently only ttyS0 and ttyS1 are supported. 485 486 Interaction with the standard serial driver is not 487 very good. 488 489 The VGA output is eventually overwritten by the real 490 console. 491 492 eata= [HW,SCSI] 493 494 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode 495 Format: <int> 496 0: polling mode 497 non-0: interrupt mode (default) 498 499 eda= [HW,PS2] 500 501 edb= [HW,PS2] 502 503 edd= [EDD] 504 Format: {"of[f]" | "sk[ipmbr]"} 505 See comment in arch/i386/boot/edd.S 506 507 eicon= [HW,ISDN] 508 Format: <id>,<membase>,<irq> 509 510 eisa_irq_edge= [PARISC,HW] 511 See header of drivers/parisc/eisa.c. 512 513 elanfreq= [IA-32] 514 See comment before function elanfreq_setup() in 515 arch/i386/kernel/cpu/cpufreq/elanfreq.c. 516 517 elevator= [IOSCHED] 518 Format: {"anticipatory" | "cfq" | "deadline" | "noop"} 519 See Documentation/block/as-iosched.txt and 520 Documentation/block/deadline-iosched.txt for details. 521 522 elfcorehdr= [IA-32, X86_64] 523 Specifies physical address of start of kernel core 524 image elf header. Generally kexec loader will 525 pass this option to capture kernel. 526 See Documentation/kdump/kdump.txt for details. 527 528 enforcing [SELINUX] Set initial enforcing status. 529 Format: {"0" | "1"} 530 See security/selinux/Kconfig help text. 531 0 -- permissive (log only, no denials). 532 1 -- enforcing (deny and log). 533 Default value is 0. 534 Value can be changed at runtime via /selinux/enforce. 535 536 es1371= [HW,OSS] 537 Format: <spdif>,[<nomix>,[<amplifier>]] 538 See also header of sound/oss/es1371.c. 539 540 ether= [HW,NET] Ethernet cards parameters 541 This option is obsoleted by the "netdev=" option, which 542 has equivalent usage. See its documentation for details. 543 544 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. 545 Format: <io>[,<irq>] 546 547 fd_mcs= [HW,SCSI] 548 See header of drivers/scsi/fd_mcs.c. 549 550 fdomain= [HW,SCSI] 551 See header of drivers/scsi/fdomain.c. 552 553 floppy= [HW] 554 See Documentation/floppy.txt. 555 556 ftape= [HW] Floppy Tape subsystem debugging options. 557 See Documentation/ftape.txt. 558 559 gamecon.map[2|3]= 560 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 561 support via parallel port (up to 5 devices per port) 562 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 563 See also Documentation/input/joystick-parport.txt 564 565 gamma= [HW,DRM] 566 567 gdth= [HW,SCSI] 568 See header of drivers/scsi/gdth.c. 569 570 gpt [EFI] Forces disk with valid GPT signature but 571 invalid Protective MBR to be treated as GPT. 572 573 gscd= [HW,CD] 574 Format: <io> 575 576 gvp11= [HW,SCSI] 577 578 hashdist= [KNL,NUMA] Large hashes allocated during boot 579 are distributed across NUMA nodes. Defaults on 580 for IA-64, off otherwise. 581 Format: 0 | 1 (for off | on) 582 583 hcl= [IA-64] SGI's Hardware Graph compatibility layer 584 585 hd= [EIDE] (E)IDE hard drive subsystem geometry 586 Format: <cyl>,<head>,<sect> 587 588 hd?= [HW] (E)IDE subsystem 589 hd?lun= See Documentation/ide.txt. 590 591 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 592 size of <nn>. This works even on boxes that have no 593 highmem otherwise. This also works to reduce highmem 594 size on bigger boxes. 595 596 hisax= [HW,ISDN] 597 See Documentation/isdn/README.HiSax. 598 599 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages. 600 601 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing 602 603 i8042.direct [HW] Put keyboard port into non-translated mode 604 i8042.dumbkbd [HW] Pretend that controller can only read data from 605 keyboard and cannot control its state 606 (Don't attempt to blink the leds) 607 i8042.noaux [HW] Don't check for auxiliary (== mouse) port 608 i8042.nokbd [HW] Don't check/create keyboard port 609 i8042.nomux [HW] Don't check presence of an active multiplexing 610 controller 611 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 612 controllers 613 i8042.panicblink= 614 [HW] Frequency with which keyboard LEDs should blink 615 when kernel panics (default is 0.5 sec) 616 i8042.reset [HW] Reset the controller during init and cleanup 617 i8042.unlock [HW] Unlock (ignore) the keylock 618 619 i810= [HW,DRM] 620 621 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 622 indicates that the driver is running on unsupported 623 hardware. 624 i8k.force [HW] Activate i8k driver even if SMM BIOS signature 625 does not match list of supported models. 626 i8k.power_status 627 [HW] Report power status in /proc/i8k 628 (disabled by default) 629 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 630 capability is set. 631 632 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter 633 See Documentation/mca.txt. 634 635 icn= [HW,ISDN] 636 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 637 638 ide= [HW] (E)IDE subsystem 639 Format: ide=nodma or ide=doubler or ide=reverse 640 See Documentation/ide.txt. 641 642 ide?= [HW] (E)IDE subsystem 643 Format: ide?=noprobe or chipset specific parameters. 644 See Documentation/ide.txt. 645 646 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed 647 See Documentation/ide.txt. 648 649 idle= [HW] 650 Format: idle=poll or idle=halt 651 652 ihash_entries= [KNL] 653 Set number of hash buckets for inode cache. 654 655 in2000= [HW,SCSI] 656 See header of drivers/scsi/in2000.c. 657 658 init= [KNL] 659 Format: <full_path> 660 Run specified binary instead of /sbin/init as init 661 process. 662 663 initcall_debug [KNL] Trace initcalls as they are executed. Useful 664 for working out where the kernel is dying during 665 startup. 666 667 initrd= [BOOT] Specify the location of the initial ramdisk 668 669 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 670 Format: <irq> 671 672 combined_mode= [HW] control which driver uses IDE ports in combined 673 mode: legacy IDE driver, libata, or both 674 (in the libata case, libata.atapi_enabled=1 may be 675 useful as well). Note that using the ide or libata 676 options may affect your device naming (e.g. by 677 changing hdc to sdb). 678 Format: combined (default), ide, or libata 679 680 inttest= [IA64] 681 682 io7= [HW] IO7 for Marvel based alpha systems 683 See comment before marvel_specify_io7 in 684 arch/alpha/kernel/core_marvel.c. 685 686 ip= [IP_PNP] 687 See Documentation/nfsroot.txt. 688 689 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards 690 See comment before ip2_setup() in drivers/char/ip2.c. 691 692 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller 693 See header of drivers/scsi/ips.c. 694 695 ports= [IP_VS_FTP] IPVS ftp helper module 696 Default is 21. 697 Up to 8 (IP_VS_APP_MAX_PORTS) ports 698 may be specified. 699 Format: <port>,<port>.... 700 701 irqfixup [HW] 702 When an interrupt is not handled search all handlers 703 for it. Intended to get systems with badly broken 704 firmware running. 705 706 irqpoll [HW] 707 When an interrupt is not handled search all handlers 708 for it. Also check all handlers each timer 709 interrupt. Intended to get systems with badly broken 710 firmware running. 711 712 isapnp= [ISAPNP] 713 Format: <RDP>,<reset>,<pci_scan>,<verbosity> 714 715 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. 716 Format: <cpu number>,...,<cpu number> 717 This option can be used to specify one or more CPUs 718 to isolate from the general SMP balancing and scheduling 719 algorithms. The only way to move a process onto or off 720 an "isolated" CPU is via the CPU affinity syscalls. 721 <cpu number> begins at 0 and the maximum value is 722 "number of CPUs in system - 1". 723 724 This option is the preferred way to isolate CPUs. The 725 alternative -- manually setting the CPU mask of all 726 tasks in the system -- can cause problems and 727 suboptimal load balancer performance. 728 729 isp16= [HW,CD] 730 Format: <io>,<irq>,<dma>,<setup> 731 732 iucv= [HW,NET] 733 734 js= [HW,JOY] Analog joystick 735 See Documentation/input/joystick.txt. 736 737 keepinitrd [HW,ARM] 738 739 kstack=N [IA-32,X86-64] Print N words from the kernel stack 740 in oops dumps. 741 742 l2cr= [PPC] 743 744 lapic [IA-32,APIC] Enable the local APIC even if BIOS 745 disabled it. 746 747 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip 748 Format: addr:<io>,irq:<irq> 749 750 llsc*= [IA64] See function print_params() in 751 arch/ia64/sn/kernel/llsc4.c. 752 753 load_ramdisk= [RAM] List of ramdisks to load from floppy 754 See Documentation/ramdisk.txt. 755 756 lockd.nlm_grace_period=P [NFS] Assign grace period. 757 Format: <integer> 758 759 lockd.nlm_tcpport=N [NFS] Assign TCP port. 760 Format: <integer> 761 762 lockd.nlm_timeout=T [NFS] Assign timeout value. 763 Format: <integer> 764 765 lockd.nlm_udpport=M [NFS] Assign UDP port. 766 Format: <integer> 767 768 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 769 Format: <irq> 770 771 loglevel= All Kernel Messages with a loglevel smaller than the 772 console loglevel will be printed to the console. It can 773 also be changed with klogd or other programs. The 774 loglevels are defined as follows: 775 776 0 (KERN_EMERG) system is unusable 777 1 (KERN_ALERT) action must be taken immediately 778 2 (KERN_CRIT) critical conditions 779 3 (KERN_ERR) error conditions 780 4 (KERN_WARNING) warning conditions 781 5 (KERN_NOTICE) normal but significant condition 782 6 (KERN_INFO) informational 783 7 (KERN_DEBUG) debug-level messages 784 785 log_buf_len=n Sets the size of the printk ring buffer, in bytes. 786 Format: { n | nk | nM } 787 n must be a power of two. The default size 788 is set in the kernel config file. 789 790 lp=0 [LP] Specify parallel ports to use, e.g, 791 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 792 lp=reset first parallel port). 'lp=0' disables the 793 lp=auto printer driver. 'lp=reset' (which can be 794 specified in addition to the ports) causes 795 attached printers to be reset. Using 796 lp=port1,port2,... specifies the parallel ports 797 to associate lp devices with, starting with 798 lp0. A port specification may be 'none' to skip 799 that lp device, or a parport name such as 800 'parport0'. Specifying 'lp=auto' instead of a 801 port specification list means that device IDs 802 from each port should be examined, to see if 803 an IEEE 1284-compliant printer is attached; if 804 so, the driver will manage that printer. 805 See also header of drivers/char/lp.c. 806 807 lpj=n [KNL] 808 Sets loops_per_jiffy to given constant, thus avoiding 809 time-consuming boot-time autodetection (up to 250 ms per 810 CPU). 0 enables autodetection (default). To determine 811 the correct value for your kernel, boot with normal 812 autodetection and see what value is printed. Note that 813 on SMP systems the preset will be applied to all CPUs, 814 which is likely to cause problems if your CPUs need 815 significantly divergent settings. An incorrect value 816 will cause delays in the kernel to be wrong, leading to 817 unpredictable I/O errors and other breakage. Although 818 unlikely, in the extreme case this might damage your 819 hardware. 820 821 ltpc= [NET] 822 Format: <io>,<irq>,<dma> 823 824 mac5380= [HW,SCSI] Format: 825 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> 826 827 mac53c9x= [HW,SCSI] Format: 828 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> 829 830 machvec= [IA64] Force the use of a particular machine-vector 831 (machvec) in a generic kernel. 832 Example: machvec=hpzx1_swiotlb 833 834 max_loop= [LOOP] Maximum number of loopback devices that can 835 be mounted 836 Format: <1-256> 837 838 maxcpus= [SMP] Maximum number of processors that an SMP kernel 839 should make use of 840 841 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or 842 equal to this physical address is ignored. 843 844 max_luns= [SCSI] Maximum number of LUNs to probe. 845 Should be between 1 and 2^32-1. 846 847 max_report_luns= 848 [SCSI] Maximum number of LUNs received. 849 Should be between 1 and 16384. 850 851 mca-pentium [BUGS=IA-32] 852 853 mcatest= [IA-64] 854 855 mcd= [HW,CD] 856 Format: <port>,<irq>,<mitsumi_bug_93_wait> 857 858 mcdx= [HW,CD] 859 860 mce [IA-32] Machine Check Exception 861 862 md= [HW] RAID subsystems devices and level 863 See Documentation/md.txt. 864 865 mdacon= [MDA] 866 Format: <first>,<last> 867 Specifies range of consoles to be captured by the MDA. 868 869 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 870 Amount of memory to be used when the kernel is not able 871 to see the whole system memory or for test. 872 [IA-32] Use together with memmap= to avoid physical 873 address space collisions. Without memmap= PCI devices 874 could be placed at addresses belonging to unused RAM. 875 876 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel 877 memory. 878 879 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact 880 E820 memory map, as specified by the user. 881 Such memmap=exactmap lines can be constructed based on 882 BIOS output or other requirements. See the memmap=nn@ss 883 option description. 884 885 memmap=nn[KMG]@ss[KMG] 886 [KNL] Force usage of a specific region of memory 887 Region of memory to be used, from ss to ss+nn. 888 889 memmap=nn[KMG]#ss[KMG] 890 [KNL,ACPI] Mark specific memory as ACPI data. 891 Region of memory to be used, from ss to ss+nn. 892 893 memmap=nn[KMG]$ss[KMG] 894 [KNL,ACPI] Mark specific memory as reserved. 895 Region of memory to be used, from ss to ss+nn. 896 897 meye.*= [HW] Set MotionEye Camera parameters 898 See Documentation/video4linux/meye.txt. 899 900 mga= [HW,DRM] 901 902 migration_cost= 903 [KNL,SMP] debug: override scheduler migration costs 904 Format: <level-1-usecs>,<level-2-usecs>,... 905 This debugging option can be used to override the 906 default scheduler migration cost matrix. The numbers 907 are indexed by 'CPU domain distance'. 908 E.g. migration_cost=1000,2000,3000 on an SMT NUMA 909 box will set up an intra-core migration cost of 910 1 msec, an inter-core migration cost of 2 msecs, 911 and an inter-node migration cost of 3 msecs. 912 913 WARNING: using the wrong values here can break 914 scheduler performance, so it's only for scheduler 915 development purposes, not production environments. 916 917 migration_debug= 918 [KNL,SMP] migration cost auto-detect verbosity 919 Format=<0|1|2> 920 If a system's migration matrix reported at bootup 921 seems erroneous then this option can be used to 922 increase verbosity of the detection process. 923 We default to 0 (no extra messages), 1 will print 924 some more information, and 2 will be really 925 verbose (probably only useful if you also have a 926 serial console attached to the system). 927 928 migration_factor= 929 [KNL,SMP] multiply/divide migration costs by a factor 930 Format=<percent> 931 This debug option can be used to proportionally 932 increase or decrease the auto-detected migration 933 costs for all entries of the migration matrix. 934 E.g. migration_factor=150 will increase migration 935 costs by 50%. (and thus the scheduler will be less 936 eager migrating cache-hot tasks) 937 migration_factor=80 will decrease migration costs 938 by 20%. (thus the scheduler will be more eager to 939 migrate tasks) 940 941 WARNING: using the wrong values here can break 942 scheduler performance, so it's only for scheduler 943 development purposes, not production environments. 944 945 mousedev.tap_time= 946 [MOUSE] Maximum time between finger touching and 947 leaving touchpad surface for touch to be considered 948 a tap and be reported as a left button click (for 949 touchpads working in absolute mode only). 950 Format: <msecs> 951 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 952 reporting absolute coordinates, such as tablets 953 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 954 reporting absolute coordinates, such as tablets 955 956 mpu401= [HW,OSS] 957 Format: <io>,<irq> 958 959 MTD_Partition= [MTD] 960 Format: <name>,<region-number>,<size>,<offset> 961 962 MTD_Region= [MTD] Format: 963 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 964 965 mtdparts= [MTD] 966 See drivers/mtd/cmdline.c. 967 968 mtouchusb.raw_coordinates= 969 [HW] Make the MicroTouch USB driver use raw coordinates 970 ('y', default) or cooked coordinates ('n') 971 972 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 973 974 NCR_D700= [HW,SCSI] 975 See header of drivers/scsi/NCR_D700.c. 976 977 ncr5380= [HW,SCSI] 978 979 ncr53c400= [HW,SCSI] 980 981 ncr53c400a= [HW,SCSI] 982 983 ncr53c406a= [HW,SCSI] 984 985 ncr53c8xx= [HW,SCSI] 986 987 netdev= [NET] Network devices parameters 988 Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 989 Note that mem_start is often overloaded to mean 990 something different and driver-specific. 991 This usage is only documented in each driver source 992 file if at all. 993 994 nfsaddrs= [NFS] 995 See Documentation/nfsroot.txt. 996 997 nfsroot= [NFS] nfs root filesystem for disk-less boxes. 998 See Documentation/nfsroot.txt. 999 1000 nfs.callback_tcpport= 1001 [NFS] set the TCP port on which the NFSv4 callback 1002 channel should listen. 1003 1004 nfs.idmap_cache_timeout= 1005 [NFS] set the maximum lifetime for idmapper cache 1006 entries. 1007 1008 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels 1009 1010 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths 1011 emulation library even if a 387 maths coprocessor 1012 is present. 1013 1014 noalign [KNL,ARM] 1015 1016 noapic [SMP,APIC] Tells the kernel to not make use of any 1017 IOAPICs that may be present in the system. 1018 1019 noasync [HW,M68K] Disables async and sync negotiation for 1020 all devices. 1021 1022 nobats [PPC] Do not use BATs for mapping kernel lowmem 1023 on "Classic" PPC cores. 1024 1025 nocache [ARM] 1026 1027 nodelayacct [KNL] Disable per-task delay accounting 1028 1029 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. 1030 1031 noexec [IA-64] 1032 1033 noexec [IA-32,X86-64] 1034 noexec=on: enable non-executable mappings (default) 1035 noexec=off: disable nn-executable mappings 1036 1037 nofxsr [BUGS=IA-32] Disables x86 floating point extended 1038 register save and restore. The kernel will only save 1039 legacy floating-point registers on task switch. 1040 1041 nohlt [BUGS=ARM] 1042 1043 no-hlt [BUGS=IA-32] Tells the kernel that the hlt 1044 instruction doesn't work correctly and not to 1045 use it. 1046 1047 nohalt [IA-64] Tells the kernel not to use the power saving 1048 function PAL_HALT_LIGHT when idle. This increases 1049 power-consumption. On the positive side, it reduces 1050 interrupt wake-up latency, which may improve performance 1051 in certain environments such as networked servers or 1052 real-time systems. 1053 1054 noirqdebug [IA-32] Disables the code which attempts to detect and 1055 disable unhandled interrupt sources. 1056 1057 noisapnp [ISAPNP] Disables ISA PnP code. 1058 1059 noinitrd [RAM] Tells the kernel not to load any configured 1060 initial RAM disk. 1061 1062 nointroute [IA-64] 1063 1064 nolapic [IA-32,APIC] Do not enable or use the local APIC. 1065 1066 noltlbs [PPC] Do not use large page/tlb entries for kernel 1067 lowmem mapping on PPC40x. 1068 1069 nomca [IA-64] Disable machine check abort handling 1070 1071 nomce [IA-32] Machine Check Exception 1072 1073 noresidual [PPC] Don't use residual data on PReP machines. 1074 1075 noresume [SWSUSP] Disables resume and restores original swap 1076 space. 1077 1078 no-scroll [VGA] Disables scrollback. 1079 This is required for the Braillex ib80-piezo Braille 1080 reader made by F.H. Papenmeier (Germany). 1081 1082 nosbagart [IA-64] 1083 1084 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support. 1085 1086 nosmp [SMP] Tells an SMP kernel to act as a UP kernel. 1087 1088 nosync [HW,M68K] Disables sync negotiation for all devices. 1089 1090 notsc [BUGS=IA-32] Disable Time Stamp Counter 1091 1092 nousb [USB] Disable the USB subsystem 1093 1094 nowb [ARM] 1095 1096 nr_uarts= [SERIAL] maximum number of UARTs to be registered. 1097 1098 opl3= [HW,OSS] 1099 Format: <io> 1100 1101 opl3sa2= [HW,OSS] Format: 1102 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple] 1103 1104 oprofile.timer= [HW] 1105 Use timer interrupt instead of performance counters 1106 1107 optcd= [HW,CD] 1108 Format: <io> 1109 1110 osst= [HW,SCSI] SCSI Tape Driver 1111 Format: <buffer_size>,<write_threshold> 1112 See also Documentation/scsi/st.txt. 1113 1114 panic= [KNL] Kernel behaviour on panic 1115 Format: <timeout> 1116 1117 parkbd.port= [HW] Parallel port number the keyboard adapter is 1118 connected to, default is 0. 1119 Format: <parport#> 1120 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 1121 0 for XT, 1 for AT (default is AT). 1122 Format: <mode> 1123 1124 parport= [HW,PPT] Specify parallel ports. 0 disables. 1125 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 1126 Use 'auto' to force the driver to use any 1127 IRQ/DMA settings detected (the default is to 1128 ignore detected IRQ/DMA settings because of 1129 possible conflicts). You can specify the base 1130 address, IRQ, and DMA settings; IRQ and DMA 1131 should be numbers, or 'auto' (for using detected 1132 settings on that particular port), or 'nofifo' 1133 (to avoid using a FIFO even if it is detected). 1134 Parallel ports are assigned in the order they 1135 are specified on the command line, starting 1136 with parport0. 1137 1138 parport_init_mode= [HW,PPT] 1139 Configure VIA parallel port to operate in 1140 a specific mode. This is necessary on Pegasos 1141 computer where firmware has no options for setting 1142 up parallel port mode and sets it to spp. 1143 Currently this function knows 686a and 8231 chips. 1144 Format: [spp|ps2|epp|ecp|ecpepp] 1145 1146 pas2= [HW,OSS] Format: 1147 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16> 1148 1149 pas16= [HW,SCSI] 1150 See header of drivers/scsi/pas16.c. 1151 1152 pause_on_oops= 1153 Halt all CPUs after the first oops has been printed for 1154 the specified number of seconds. This is to be used if 1155 your oopses keep scrolling off the screen. 1156 1157 pcbit= [HW,ISDN] 1158 1159 pcd. [PARIDE] 1160 See header of drivers/block/paride/pcd.c. 1161 See also Documentation/paride.txt. 1162 1163 pci=option[,option...] [PCI] various PCI subsystem options: 1164 off [IA-32] don't probe for the PCI bus 1165 bios [IA-32] force use of PCI BIOS, don't access 1166 the hardware directly. Use this if your machine 1167 has a non-standard PCI host bridge. 1168 nobios [IA-32] disallow use of PCI BIOS, only direct 1169 hardware access methods are allowed. Use this 1170 if you experience crashes upon bootup and you 1171 suspect they are caused by the BIOS. 1172 conf1 [IA-32] Force use of PCI Configuration 1173 Mechanism 1. 1174 conf2 [IA-32] Force use of PCI Configuration 1175 Mechanism 2. 1176 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI 1177 Configuration 1178 nomsi [MSI] If the PCI_MSI kernel config parameter is 1179 enabled, this kernel boot option can be used to 1180 disable the use of MSI interrupts system-wide. 1181 nosort [IA-32] Don't sort PCI devices according to 1182 order given by the PCI BIOS. This sorting is 1183 done to get a device order compatible with 1184 older kernels. 1185 biosirq [IA-32] Use PCI BIOS calls to get the interrupt 1186 routing table. These calls are known to be buggy 1187 on several machines and they hang the machine 1188 when used, but on other computers it's the only 1189 way to get the interrupt routing table. Try 1190 this option if the kernel is unable to allocate 1191 IRQs or discover secondary PCI buses on your 1192 motherboard. 1193 rom [IA-32] Assign address space to expansion ROMs. 1194 Use with caution as certain devices share 1195 address decoders between ROMs and other 1196 resources. 1197 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be 1198 assigned automatically to PCI devices. You can 1199 make the kernel exclude IRQs of your ISA cards 1200 this way. 1201 pirqaddr=0xAAAAA [IA-32] Specify the physical address 1202 of the PIRQ table (normally generated 1203 by the BIOS) if it is outside the 1204 F0000h-100000h range. 1205 lastbus=N [IA-32] Scan all buses thru bus #N. Can be 1206 useful if the kernel is unable to find your 1207 secondary buses and you want to tell it 1208 explicitly which ones they are. 1209 assign-busses [IA-32] Always assign all PCI bus 1210 numbers ourselves, overriding 1211 whatever the firmware may have done. 1212 usepirqmask [IA-32] Honor the possible IRQ mask stored 1213 in the BIOS $PIR table. This is needed on 1214 some systems with broken BIOSes, notably 1215 some HP Pavilion N5400 and Omnibook XE3 1216 notebooks. This will have no effect if ACPI 1217 IRQ routing is enabled. 1218 noacpi [IA-32] Do not use ACPI for IRQ routing 1219 or for PCI scanning. 1220 routeirq Do IRQ routing for all PCI devices. 1221 This is normally done in pci_enable_device(), 1222 so this option is a temporary workaround 1223 for broken drivers that don't call it. 1224 firmware [ARM] Do not re-enumerate the bus but instead 1225 just use the configuration from the 1226 bootloader. This is currently used on 1227 IXP2000 systems where the bus has to be 1228 configured a certain way for adjunct CPUs. 1229 noearly [X86] Don't do any early type 1 scanning. 1230 This might help on some broken boards which 1231 machine check when some devices' config space 1232 is read. But various workarounds are disabled 1233 and some IOMMU drivers will not work. 1234 bfsort Sort PCI devices into breadth-first order. 1235 This sorting is done to get a device 1236 order compatible with older (<= 2.4) kernels. 1237 nobfsort Don't sort PCI devices into breadth-first order. 1238 1239 pcmv= [HW,PCMCIA] BadgePAD 4 1240 1241 pd. [PARIDE] 1242 See Documentation/paride.txt. 1243 1244 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 1245 boot time. 1246 Format: { 0 | 1 } 1247 See arch/parisc/kernel/pdc_chassis.c 1248 1249 pf. [PARIDE] 1250 See Documentation/paride.txt. 1251 1252 pg. [PARIDE] 1253 See Documentation/paride.txt. 1254 1255 pirq= [SMP,APIC] Manual mp-table setup 1256 See Documentation/i386/IO-APIC.txt. 1257 1258 plip= [PPT,NET] Parallel port network link 1259 Format: { parport<nr> | timid | 0 } 1260 See also Documentation/parport.txt. 1261 1262 pnpacpi= [ACPI] 1263 { off } 1264 1265 pnpbios= [ISAPNP] 1266 { on | off | curr | res | no-curr | no-res } 1267 1268 pnp_reserve_irq= 1269 [ISAPNP] Exclude IRQs for the autoconfiguration 1270 1271 pnp_reserve_dma= 1272 [ISAPNP] Exclude DMAs for the autoconfiguration 1273 1274 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 1275 Ranges are in pairs (I/O port base and size). 1276 1277 pnp_reserve_mem= 1278 [ISAPNP] Exclude memory regions for the 1279 autoconfiguration. 1280 Ranges are in pairs (memory base and size). 1281 1282 profile= [KNL] Enable kernel profiling via /proc/profile 1283 Format: [schedule,]<number> 1284 Param: "schedule" - profile schedule points. 1285 Param: <number> - step/bucket size as a power of 2 for 1286 statistical time based profiling. 1287 1288 processor.max_cstate= [HW,ACPI] 1289 Limit processor to maximum C-state 1290 max_cstate=9 overrides any DMI blacklist limit. 1291 1292 processor.nocst [HW,ACPI] 1293 Ignore the _CST method to determine C-states, 1294 instead using the legacy FADT method 1295 1296 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 1297 before loading. 1298 See Documentation/ramdisk.txt. 1299 1300 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 1301 probe for; one of (bare|imps|exps|lifebook|any). 1302 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 1303 per second. 1304 psmouse.resetafter= [HW,MOUSE] 1305 Try to reset the device after so many bad packets 1306 (0 = never). 1307 psmouse.resolution= 1308 [HW,MOUSE] Set desired mouse resolution, in dpi. 1309 psmouse.smartscroll= 1310 [HW,MOUSE] Controls Logitech smartscroll autorepeat. 1311 0 = disabled, 1 = enabled (default). 1312 1313 pss= [HW,OSS] Personal Sound System (ECHO ESC614) 1314 Format: 1315 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> 1316 1317 pt. [PARIDE] 1318 See Documentation/paride.txt. 1319 1320 quiet [KNL] Disable most log messages 1321 1322 r128= [HW,DRM] 1323 1324 raid= [HW,RAID] 1325 See Documentation/md.txt. 1326 1327 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated] 1328 See Documentation/ramdisk.txt. 1329 1330 ramdisk_blocksize= [RAM] 1331 See Documentation/ramdisk.txt. 1332 1333 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 1334 New name for the ramdisk parameter. 1335 See Documentation/ramdisk.txt. 1336 1337 rcu.blimit= [KNL,BOOT] Set maximum number of finished 1338 RCU callbacks to process in one batch. 1339 1340 rcu.qhimark= [KNL,BOOT] Set threshold of queued 1341 RCU callbacks over which batch limiting is disabled. 1342 1343 rcu.qlowmark= [KNL,BOOT] Set threshold of queued 1344 RCU callbacks below which batch limiting is re-enabled. 1345 1346 rdinit= [KNL] 1347 Format: <full_path> 1348 Run specified binary instead of /init from the ramdisk, 1349 used for early userspace startup. See initrd. 1350 1351 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode 1352 Format: <reboot_mode>[,<reboot_mode2>[,...]] 1353 See arch/*/kernel/reboot.c or arch/*/kernel/process.c 1354 1355 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area 1356 1357 reservetop= [IA-32] 1358 Format: nn[KMG] 1359 Reserves a hole at the top of the kernel virtual 1360 address space. 1361 1362 reset_devices [KNL] Force drivers to reset the underlying device 1363 during initialization. 1364 1365 resume= [SWSUSP] 1366 Specify the partition device for software suspend 1367 1368 rhash_entries= [KNL,NET] 1369 Set number of hash buckets for route cache 1370 1371 riscom8= [HW,SERIAL] 1372 Format: <io_board1>[,<io_board2>[,...<io_boardN>]] 1373 1374 ro [KNL] Mount root device read-only on boot 1375 1376 root= [KNL] Root filesystem 1377 1378 rootdelay= [KNL] Delay (in seconds) to pause before attempting to 1379 mount the root filesystem 1380 1381 rootflags= [KNL] Set root filesystem mount option string 1382 1383 rootfstype= [KNL] Set root filesystem type 1384 1385 rw [KNL] Mount root device read-write on boot 1386 1387 S [KNL] Run init in single mode 1388 1389 sa1100ir [NET] 1390 See drivers/net/irda/sa1100_ir.c. 1391 1392 sb= [HW,OSS] 1393 Format: <io>,<irq>,<dma>,<dma2> 1394 1395 sbni= [NET] Granch SBNI12 leased line adapter 1396 1397 sbpcd= [HW,CD] Soundblaster CD adapter 1398 Format: <io>,<type> 1399 See a comment before function sbpcd_setup() in 1400 drivers/cdrom/sbpcd.c. 1401 1402 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver 1403 Format: <io>[,<timeout>[,<isapnp>]] 1404 1405 scsi_debug_*= [SCSI] 1406 See drivers/scsi/scsi_debug.c. 1407 1408 scsi_default_dev_flags= 1409 [SCSI] SCSI default device flags 1410 Format: <integer> 1411 1412 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model 1413 Format: <vendor>:<model>:<flags> 1414 (flags are integer value) 1415 1416 scsi_logging= [SCSI] 1417 1418 selinux [SELINUX] Disable or enable SELinux at boot time. 1419 Format: { "0" | "1" } 1420 See security/selinux/Kconfig help text. 1421 0 -- disable. 1422 1 -- enable. 1423 Default value is set via kernel config option. 1424 If enabled at boot time, /selinux/disable can be used 1425 later to disable prior to initial policy load. 1426 1427 selinux_compat_net = 1428 [SELINUX] Set initial selinux_compat_net flag value. 1429 Format: { "0" | "1" } 1430 0 -- use new secmark-based packet controls 1431 1 -- use legacy packet controls 1432 Default value is 0 (preferred). 1433 Value can be changed at runtime via 1434 /selinux/compat_net. 1435 1436 serialnumber [BUGS=IA-32] 1437 1438 sg_def_reserved_size= [SCSI] 1439 1440 shapers= [NET] 1441 Maximal number of shapers. 1442 1443 sim710= [SCSI,HW] 1444 See header of drivers/scsi/sim710.c. 1445 1446 simeth= [IA-64] 1447 simscsi= 1448 1449 sjcd= [HW,CD] 1450 Format: <io>,<irq>,<dma> 1451 See header of drivers/cdrom/sjcd.c. 1452 1453 slram= [HW,MTD] 1454 1455 smart2= [HW] 1456 Format: <io1>[,<io2>[,...,<io8>]] 1457 1458 snd-ad1816a= [HW,ALSA] 1459 1460 snd-ad1848= [HW,ALSA] 1461 1462 snd-ali5451= [HW,ALSA] 1463 1464 snd-als100= [HW,ALSA] 1465 1466 snd-als4000= [HW,ALSA] 1467 1468 snd-azt2320= [HW,ALSA] 1469 1470 snd-cmi8330= [HW,ALSA] 1471 1472 snd-cmipci= [HW,ALSA] 1473 1474 snd-cs4231= [HW,ALSA] 1475 1476 snd-cs4232= [HW,ALSA] 1477 1478 snd-cs4236= [HW,ALSA] 1479 1480 snd-cs4281= [HW,ALSA] 1481 1482 snd-cs46xx= [HW,ALSA] 1483 1484 snd-dt019x= [HW,ALSA] 1485 1486 snd-dummy= [HW,ALSA] 1487 1488 snd-emu10k1= [HW,ALSA] 1489 1490 snd-ens1370= [HW,ALSA] 1491 1492 snd-ens1371= [HW,ALSA] 1493 1494 snd-es968= [HW,ALSA] 1495 1496 snd-es1688= [HW,ALSA] 1497 1498 snd-es18xx= [HW,ALSA] 1499 1500 snd-es1938= [HW,ALSA] 1501 1502 snd-es1968= [HW,ALSA] 1503 1504 snd-fm801= [HW,ALSA] 1505 1506 snd-gusclassic= [HW,ALSA] 1507 1508 snd-gusextreme= [HW,ALSA] 1509 1510 snd-gusmax= [HW,ALSA] 1511 1512 snd-hdsp= [HW,ALSA] 1513 1514 snd-ice1712= [HW,ALSA] 1515 1516 snd-intel8x0= [HW,ALSA] 1517 1518 snd-interwave= [HW,ALSA] 1519 1520 snd-interwave-stb= 1521 [HW,ALSA] 1522 1523 snd-korg1212= [HW,ALSA] 1524 1525 snd-maestro3= [HW,ALSA] 1526 1527 snd-mpu401= [HW,ALSA] 1528 1529 snd-mtpav= [HW,ALSA] 1530 1531 snd-nm256= [HW,ALSA] 1532 1533 snd-opl3sa2= [HW,ALSA] 1534 1535 snd-opti92x-ad1848= 1536 [HW,ALSA] 1537 1538 snd-opti92x-cs4231= 1539 [HW,ALSA] 1540 1541 snd-opti93x= [HW,ALSA] 1542 1543 snd-pmac= [HW,ALSA] 1544 1545 snd-rme32= [HW,ALSA] 1546 1547 snd-rme96= [HW,ALSA] 1548 1549 snd-rme9652= [HW,ALSA] 1550 1551 snd-sb8= [HW,ALSA] 1552 1553 snd-sb16= [HW,ALSA] 1554 1555 snd-sbawe= [HW,ALSA] 1556 1557 snd-serial= [HW,ALSA] 1558 1559 snd-sgalaxy= [HW,ALSA] 1560 1561 snd-sonicvibes= [HW,ALSA] 1562 1563 snd-sun-amd7930= 1564 [HW,ALSA] 1565 1566 snd-sun-cs4231= [HW,ALSA] 1567 1568 snd-trident= [HW,ALSA] 1569 1570 snd-usb-audio= [HW,ALSA,USB] 1571 1572 snd-via82xx= [HW,ALSA] 1573 1574 snd-virmidi= [HW,ALSA] 1575 1576 snd-wavefront= [HW,ALSA] 1577 1578 snd-ymfpci= [HW,ALSA] 1579 1580 sonycd535= [HW,CD] 1581 Format: <io>[,<irq>] 1582 1583 sonypi.*= [HW] Sony Programmable I/O Control Device driver 1584 See Documentation/sonypi.txt 1585 1586 specialix= [HW,SERIAL] Specialix multi-serial port adapter 1587 See Documentation/specialix.txt. 1588 1589 spia_io_base= [HW,MTD] 1590 spia_fio_base= 1591 spia_pedr= 1592 spia_peddr= 1593 1594 sscape= [HW,OSS] 1595 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq> 1596 1597 st= [HW,SCSI] SCSI tape parameters (buffers, etc.) 1598 See Documentation/scsi/st.txt. 1599 1600 st0x= [HW,SCSI] 1601 See header of drivers/scsi/seagate.c. 1602 1603 sti= [PARISC,HW] 1604 Format: <num> 1605 Set the STI (builtin display/keyboard on the HP-PARISC 1606 machines) console (graphic card) which should be used 1607 as the initial boot-console. 1608 See also comment in drivers/video/console/sticore.c. 1609 1610 sti_font= [HW] 1611 See comment in drivers/video/console/sticore.c. 1612 1613 stifb= [HW] 1614 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 1615 1616 swiotlb= [IA-64] Number of I/O TLB slabs 1617 1618 switches= [HW,M68k] 1619 1620 sym53c416= [HW,SCSI] 1621 See header of drivers/scsi/sym53c416.c. 1622 1623 t128= [HW,SCSI] 1624 See header of drivers/scsi/t128.c. 1625 1626 tdfx= [HW,DRM] 1627 1628 thash_entries= [KNL,NET] 1629 Set number of hash buckets for TCP connection 1630 1631 time Show timing data prefixed to each printk message line 1632 1633 clocksource= [GENERIC_TIME] Override the default clocksource 1634 Override the default clocksource and use the clocksource 1635 with the name specified. 1636 1637 tipar.timeout= [HW,PPT] 1638 Set communications timeout in tenths of a second 1639 (default 15). 1640 1641 tipar.delay= [HW,PPT] 1642 Set inter-bit delay in microseconds (default 10). 1643 1644 tmc8xx= [HW,SCSI] 1645 See header of drivers/scsi/seagate.c. 1646 1647 tmscsim= [HW,SCSI] 1648 See comment before function dc390_setup() in 1649 drivers/scsi/tmscsim.c. 1650 1651 tp720= [HW,PS2] 1652 1653 trix= [HW,OSS] MediaTrix AudioTrix Pro 1654 Format: 1655 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq> 1656 1657 tsdev.xres= [TS] Horizontal screen resolution. 1658 tsdev.yres= [TS] Vertical screen resolution. 1659 1660 turbografx.map[2|3]= [HW,JOY] 1661 TurboGraFX parallel port interface 1662 Format: 1663 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 1664 See also Documentation/input/joystick-parport.txt 1665 1666 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter 1667 See header of drivers/scsi/u14-34f.c. 1668 1669 uart401= [HW,OSS] 1670 Format: <io>,<irq> 1671 1672 uart6850= [HW,OSS] 1673 Format: <io>,<irq> 1674 1675 usbhid.mousepoll= 1676 [USBHID] The interval which mice are to be polled at. 1677 1678 vdso= [IA-32] 1679 vdso=1: enable VDSO (default) 1680 vdso=0: disable VDSO mapping 1681 1682 video= [FB] Frame buffer configuration 1683 See Documentation/fb/modedb.txt. 1684 1685 vga= [BOOT,IA-32] Select a particular video mode 1686 See Documentation/i386/boot.txt and 1687 Documentation/svga.txt. 1688 Use vga=ask for menu. 1689 This is actually a boot loader parameter; the value is 1690 passed to the kernel using a special protocol. 1691 1692 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 1693 size of <nn>. This can be used to increase the 1694 minimum size (128MB on x86). It can also be used to 1695 decrease the size and leave more room for directly 1696 mapped kernel RAM. 1697 1698 vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 1699 Format: <command> 1700 1701 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 1702 Format: <command> 1703 1704 vmpoff= [KNL,S390] Perform z/VM CP command after power off. 1705 Format: <command> 1706 1707 waveartist= [HW,OSS] 1708 Format: <io>,<irq>,<dma>,<dma2> 1709 1710 wd33c93= [HW,SCSI] 1711 See header of drivers/scsi/wd33c93.c. 1712 1713 wd7000= [HW,SCSI] 1714 See header of drivers/scsi/wd7000.c. 1715 1716 wdt= [WDT] Watchdog 1717 See Documentation/watchdog/watchdog.txt. 1718 1719 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. 1720 xd_geo= See header of drivers/block/xd.c. 1721 1722 xirc2ps_cs= [NET,PCMCIA] 1723 Format: 1724 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 1725 1726 norandmaps Don't use address space randomization 1727 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space 1728 1729 1730______________________________________________________________________ 1731 1732TODO: 1733 1734 Add documentation for ALSA options. 1735 Add more DRM drivers.