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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 AGP AGP (Accelerated Graphics Port) is enabled. 34 ALSA ALSA sound support is enabled. 35 APIC APIC support is enabled. 36 APM Advanced Power Management support is enabled. 37 AVR32 AVR32 architecture is enabled. 38 AX25 Appropriate AX.25 support is enabled. 39 BLACKFIN Blackfin architecture is enabled. 40 DRM Direct Rendering Management support is enabled. 41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled 42 EFI EFI Partitioning (GPT) is enabled 43 EIDE EIDE/ATAPI support is enabled. 44 FB The frame buffer device is enabled. 45 HW Appropriate hardware is enabled. 46 IA-64 IA-64 architecture is enabled. 47 IOSCHED More than one I/O scheduler is enabled. 48 IP_PNP IP DHCP, BOOTP, or RARP is enabled. 49 ISAPNP ISA PnP code is enabled. 50 ISDN Appropriate ISDN support is enabled. 51 JOY Appropriate joystick support is enabled. 52 LIBATA Libata driver is enabled 53 LP Printer support is enabled. 54 LOOP Loopback device support is enabled. 55 M68k M68k architecture is enabled. 56 These options have more detailed description inside of 57 Documentation/m68k/kernel-options.txt. 58 MCA MCA bus support is enabled. 59 MDA MDA console support is enabled. 60 MOUSE Appropriate mouse support is enabled. 61 MSI Message Signaled Interrupts (PCI). 62 MTD MTD (Memory Technology Device) support is enabled. 63 NET Appropriate network support is enabled. 64 NUMA NUMA support is enabled. 65 GENERIC_TIME The generic timeofday code is enabled. 66 NFS Appropriate NFS support is enabled. 67 OSS OSS sound support is enabled. 68 PV_OPS A paravirtualized kernel is enabled. 69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled. 70 PARISC The PA-RISC architecture is enabled. 71 PCI PCI bus support is enabled. 72 PCIE PCI Express support is enabled. 73 PCMCIA The PCMCIA subsystem is enabled. 74 PNP Plug & Play support is enabled. 75 PPC PowerPC architecture is enabled. 76 PPT Parallel port support is enabled. 77 PS2 Appropriate PS/2 support is enabled. 78 RAM RAM disk support is enabled. 79 ROOTPLUG The example Root Plug LSM is enabled. 80 S390 S390 architecture is enabled. 81 SCSI Appropriate SCSI support is enabled. 82 A lot of drivers has their options described inside of 83 Documentation/scsi/. 84 SECURITY Different security models are enabled. 85 SELINUX SELinux support is enabled. 86 SERIAL Serial support is enabled. 87 SH SuperH architecture is enabled. 88 SMP The kernel is an SMP kernel. 89 SPARC Sparc architecture is enabled. 90 SWSUSP Software suspend is enabled. 91 TS Appropriate touchscreen support is enabled. 92 USB USB support is enabled. 93 USBHID USB Human Interface Device support is enabled. 94 V4L Video For Linux support is enabled. 95 VGA The VGA console has been enabled. 96 VT Virtual terminal support is enabled. 97 WDT Watchdog support is enabled. 98 XT IBM PC/XT MFM hard disk support is enabled. 99 X86-32 X86-32, aka i386 architecture is enabled. 100 X86-64 X86-64 architecture is enabled. 101 More X86-64 boot options can be found in 102 Documentation/x86_64/boot-options.txt . 103 104In addition, the following text indicates that the option: 105 106 BUGS= Relates to possible processor bugs on the said processor. 107 KNL Is a kernel start-up parameter. 108 BOOT Is a boot loader parameter. 109 110Parameters denoted with BOOT are actually interpreted by the boot 111loader, and have no meaning to the kernel directly. 112Do not modify the syntax of boot loader parameters without extreme 113need or coordination with <Documentation/i386/boot.txt>. 114 115There are also arch-specific kernel-parameters not documented here. 116See for example <Documentation/x86_64/boot-options.txt>. 117 118Note that ALL kernel parameters listed below are CASE SENSITIVE, and that 119a trailing = on the name of any parameter states that that parameter will 120be entered as an environment variable, whereas its absence indicates that 121it will appear as a kernel argument readable via /proc/cmdline by programs 122running once the system is up. 123 124The number of kernel parameters is not limited, but the length of the 125complete command line (parameters including spaces etc.) is limited to 126a fixed number of characters. This limit depends on the architecture 127and is between 256 and 4096 characters. It is defined in the file 128./include/asm/setup.h as COMMAND_LINE_SIZE. 129 130 131 acpi= [HW,ACPI,X86-64,i386] 132 Advanced Configuration and Power Interface 133 Format: { force | off | ht | strict | noirq } 134 force -- enable ACPI if default was off 135 off -- disable ACPI if default was on 136 noirq -- do not use ACPI for IRQ routing 137 ht -- run only enough ACPI to enable Hyper Threading 138 strict -- Be less tolerant of platforms that are not 139 strictly ACPI specification compliant. 140 141 See also Documentation/power/pm.txt, pci=noacpi 142 143 acpi_apic_instance= [ACPI, IOAPIC] 144 Format: <int> 145 2: use 2nd APIC table, if available 146 1,0: use 1st APIC table 147 default: 0 148 149 acpi_sleep= [HW,ACPI] Sleep options 150 Format: { s3_bios, s3_mode, s3_beep } 151 See Documentation/power/video.txt for s3_bios and s3_mode. 152 s3_beep is for debugging; it makes the PC's speaker beep 153 as soon as the kernel's real-mode entry point is called. 154 155 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode 156 Format: { level | edge | high | low } 157 158 acpi_irq_balance [HW,ACPI] 159 ACPI will balance active IRQs 160 default in APIC mode 161 162 acpi_irq_nobalance [HW,ACPI] 163 ACPI will not move active IRQs (default) 164 default in PIC mode 165 166 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for 167 use by PCI 168 Format: <irq>,<irq>... 169 170 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA 171 Format: <irq>,<irq>... 172 173 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT 174 175 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 176 Format: To spoof as Windows 98: ="Microsoft Windows" 177 178 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings 179 acpi_osi="string1" # add string1 -- only one string 180 acpi_osi="!string2" # remove built-in string2 181 acpi_osi= # disable all strings 182 183 acpi_serialize [HW,ACPI] force serialization of AML methods 184 185 acpi_skip_timer_override [HW,ACPI] 186 Recognize and ignore IRQ0/pin2 Interrupt Override. 187 For broken nForce2 BIOS resulting in XT-PIC timer. 188 acpi_use_timer_override [HW,ACPI} 189 Use timer override. For some broken Nvidia NF5 boards 190 that require a timer override, but don't have 191 HPET 192 193 acpi.debug_layer= [HW,ACPI] 194 Format: <int> 195 Each bit of the <int> indicates an ACPI debug layer, 196 1: enable, 0: disable. It is useful for boot time 197 debugging. After system has booted up, it can be set 198 via /sys/module/acpi/parameters/debug_layer. 199 CONFIG_ACPI_DEBUG must be enabled for this to produce any output. 200 Available bits (add the numbers together) to enable debug output 201 for specific parts of the ACPI subsystem: 202 0x01 utilities 0x02 hardware 0x04 events 0x08 tables 203 0x10 namespace 0x20 parser 0x40 dispatcher 204 0x80 executer 0x100 resources 0x200 acpica debugger 205 0x400 os services 0x800 acpica disassembler. 206 The number can be in decimal or prefixed with 0x in hex. 207 Warning: Many of these options can produce a lot of 208 output and make your system unusable. Be very careful. 209 210 acpi.debug_level= [HW,ACPI] 211 Format: <int> 212 Each bit of the <int> indicates an ACPI debug level, 213 1: enable, 0: disable. It is useful for boot time 214 debugging. After system has booted up, it can be set 215 via /sys/module/acpi/parameters/debug_level. 216 CONFIG_ACPI_DEBUG must be enabled for this to produce any output. 217 Available bits (add the numbers together) to enable different 218 debug output levels of the ACPI subsystem: 219 0x01 error 0x02 warn 0x04 init 0x08 debug object 220 0x10 info 0x20 init names 0x40 parse 0x80 load 221 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region 222 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects 223 0x10000 resources 0x20000 user requests 0x40000 package. 224 The number can be in decimal or prefixed with 0x in hex. 225 Warning: Many of these options can produce a lot of 226 output and make your system unusable. Be very careful. 227 228 acpi_pm_good [X86-32,X86-64] 229 Override the pmtimer bug detection: force the kernel 230 to assume that this machine's pmtimer latches its value 231 and always returns good values. 232 233 agp= [AGP] 234 { off | try_unsupported } 235 off: disable AGP support 236 try_unsupported: try to drive unsupported chipsets 237 (may crash computer or cause data corruption) 238 239 enable_timer_pin_1 [i386,x86-64] 240 Enable PIN 1 of APIC timer 241 Can be useful to work around chipset bugs 242 (in particular on some ATI chipsets). 243 The kernel tries to set a reasonable default. 244 245 disable_timer_pin_1 [i386,x86-64] 246 Disable PIN 1 of APIC timer 247 Can be useful to work around chipset bugs. 248 249 ad1848= [HW,OSS] 250 Format: <io>,<irq>,<dma>,<dma2>,<type> 251 252 advansys= [HW,SCSI] 253 See header of drivers/scsi/advansys.c. 254 255 advwdt= [HW,WDT] Advantech WDT 256 Format: <iostart>,<iostop> 257 258 aedsp16= [HW,OSS] Audio Excel DSP 16 259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq> 260 See also header of sound/oss/aedsp16.c. 261 262 aha152x= [HW,SCSI] 263 See Documentation/scsi/aha152x.txt. 264 265 aha1542= [HW,SCSI] 266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]] 267 268 aic7xxx= [HW,SCSI] 269 See Documentation/scsi/aic7xxx.txt. 270 271 aic79xx= [HW,SCSI] 272 See Documentation/scsi/aic79xx.txt. 273 274 amijoy.map= [HW,JOY] Amiga joystick support 275 Map of devices attached to JOY0DAT and JOY1DAT 276 Format: <a>,<b> 277 See also Documentation/kernel/input/joystick.txt 278 279 analog.map= [HW,JOY] Analog joystick and gamepad support 280 Specifies type or capabilities of an analog joystick 281 connected to one of 16 gameports 282 Format: <type1>,<type2>,..<type16> 283 284 apc= [HW,SPARC] 285 Power management functions (SPARCstation-4/5 + deriv.) 286 Format: noidle 287 Disable APC CPU standby support. SPARCstation-Fox does 288 not play well with APC CPU idle - disable it if you have 289 APC and your system crashes randomly. 290 291 apic= [APIC,i386] Advanced Programmable Interrupt Controller 292 Change the output verbosity whilst booting 293 Format: { quiet (default) | verbose | debug } 294 Change the amount of debugging information output 295 when initialising the APIC and IO-APIC components. 296 297 apm= [APM] Advanced Power Management 298 See header of arch/i386/kernel/apm.c. 299 300 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards 301 Format: <io>,<irq>,<nodeID> 302 303 ataflop= [HW,M68k] 304 305 atarimouse= [HW,MOUSE] Atari Mouse 306 307 atascsi= [HW,SCSI] Atari SCSI 308 309 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, 310 EzKey and similar keyboards 311 312 atkbd.reset= [HW] Reset keyboard during initialization 313 314 atkbd.set= [HW] Select keyboard code set 315 Format: <int> (2 = AT (default), 3 = PS/2) 316 317 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar 318 keyboards 319 320 atkbd.softraw= [HW] Choose between synthetic and real raw mode 321 Format: <bool> (0 = real, 1 = synthetic (default)) 322 323 atkbd.softrepeat= [HW] 324 Use software keyboard repeat 325 326 autotest [IA64] 327 328 baycom_epp= [HW,AX25] 329 Format: <io>,<mode> 330 331 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem 332 Format: <io>,<mode> 333 See header of drivers/net/hamradio/baycom_par.c. 334 335 baycom_ser_fdx= [HW,AX25] 336 BayCom Serial Port AX.25 Modem (Full Duplex Mode) 337 Format: <io>,<irq>,<mode>[,<baud>] 338 See header of drivers/net/hamradio/baycom_ser_fdx.c. 339 340 baycom_ser_hdx= [HW,AX25] 341 BayCom Serial Port AX.25 Modem (Half Duplex Mode) 342 Format: <io>,<irq>,<mode> 343 See header of drivers/net/hamradio/baycom_ser_hdx.c. 344 345 boot_delay= Milliseconds to delay each printk during boot. 346 Values larger than 10 seconds (10000) are changed to 347 no delay (0). 348 Format: integer 349 350 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 351 bttv.radio= Most important insmod options are available as 352 kernel args too. 353 bttv.pll= See Documentation/video4linux/bttv/Insmod-options 354 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST 355 356 BusLogic= [HW,SCSI] 357 See drivers/scsi/BusLogic.c, comment before function 358 BusLogic_ParseDriverOptions(). 359 360 c101= [NET] Moxa C101 synchronous serial card 361 362 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. 363 Sometimes CPU hardware bugs make them report the cache 364 size incorrectly. The kernel will attempt work arounds 365 to fix known problems, but for some CPUs it is not 366 possible to determine what the correct size should be. 367 This option provides an override for these situations. 368 369 security= [SECURITY] Choose a security module to enable at boot. 370 If this boot parameter is not specified, only the first 371 security module asking for security registration will be 372 loaded. An invalid security module name will be treated 373 as if no module has been chosen. 374 375 capability.disable= 376 [SECURITY] Disable capabilities. This would normally 377 be used only if an alternative security model is to be 378 configured. Potentially dangerous and should only be 379 used if you are entirely sure of the consequences. 380 381 ccw_timeout_log [S390] 382 See Documentation/s390/CommonIO for details. 383 384 cgroup_disable= [KNL] Disable a particular controller 385 Format: {name of the controller(s) to disable} 386 {Currently supported controllers - "memory"} 387 388 checkreqprot [SELINUX] Set initial checkreqprot flag value. 389 Format: { "0" | "1" } 390 See security/selinux/Kconfig help text. 391 0 -- check protection applied by kernel (includes 392 any implied execute protection). 393 1 -- check protection requested by application. 394 Default value is set via a kernel config option. 395 Value can be changed at runtime via 396 /selinux/checkreqprot. 397 398 cio_ignore= [S390] 399 See Documentation/s390/CommonIO for details. 400 401 cio_msg= [S390] 402 See Documentation/s390/CommonIO for details. 403 404 clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 405 [Deprecated] 406 Forces specified clocksource (if available) to be used 407 when calculating gettimeofday(). If specified 408 clocksource is not available, it defaults to PIT. 409 Format: { pit | tsc | cyclone | pmtmr } 410 411 clocksource= [GENERIC_TIME] Override the default clocksource 412 Format: <string> 413 Override the default clocksource and use the clocksource 414 with the name specified. 415 Some clocksource names to choose from, depending on 416 the platform: 417 [all] jiffies (this is the base, fallback clocksource) 418 [ACPI] acpi_pm 419 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 420 pxa_timer,timer3,32k_counter,timer0_1 421 [AVR32] avr32 422 [X86-32] pit,hpet,tsc,vmi-timer; 423 scx200_hrt on Geode; cyclone on IBM x440 424 [MIPS] MIPS 425 [PARISC] cr16 426 [S390] tod 427 [SH] SuperH 428 [SPARC64] tick 429 [X86-64] hpet,tsc 430 431 clearcpuid=BITNUM [X86] 432 Disable CPUID feature X for the kernel. See 433 include/asm-x86/cpufeature.h for the valid bit numbers. 434 Note the Linux specific bits are not necessarily 435 stable over kernel options, but the vendor specific 436 ones should be. 437 Also note that user programs calling CPUID directly 438 or using the feature without checking anything 439 will still see it. This just prevents it from 440 being used by the kernel or shown in /proc/cpuinfo. 441 Also note the kernel might malfunction if you disable 442 some critical bits. 443 444 code_bytes [IA32/X86_64] How many bytes of object code to print 445 in an oops report. 446 Range: 0 - 8192 447 Default: 64 448 449 disable_8254_timer 450 enable_8254_timer 451 [IA32/X86_64] Disable/Enable interrupt 0 timer routing 452 over the 8254 in addition to over the IO-APIC. The 453 kernel tries to set a sensible default. 454 455 hpet= [X86-32,HPET] option to control HPET usage 456 Format: { enable (default) | disable | force } 457 disable: disable HPET and use PIT instead 458 force: allow force enabled of undocumented chips (ICH4, 459 VIA, nVidia) 460 461 com20020= [HW,NET] ARCnet - COM20020 chipset 462 Format: 463 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 464 465 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 466 Format: <io>[,<irq>] 467 468 com90xx= [HW,NET] 469 ARCnet - COM90xx chipset (memory-mapped buffers) 470 Format: <io>[,<irq>[,<memstart>]] 471 472 condev= [HW,S390] console device 473 conmode= 474 475 console= [KNL] Output console device and options. 476 477 tty<n> Use the virtual console device <n>. 478 479 ttyS<n>[,options] 480 ttyUSB0[,options] 481 Use the specified serial port. The options are of 482 the form "bbbbpnf", where "bbbb" is the baud rate, 483 "p" is parity ("n", "o", or "e"), "n" is number of 484 bits, and "f" is flow control ("r" for RTS or 485 omit it). Default is "9600n8". 486 487 See Documentation/serial-console.txt for more 488 information. See 489 Documentation/networking/netconsole.txt for an 490 alternative. 491 492 uart[8250],io,<addr>[,options] 493 uart[8250],mmio,<addr>[,options] 494 Start an early, polled-mode console on the 8250/16550 495 UART at the specified I/O port or MMIO address, 496 switching to the matching ttyS device later. The 497 options are the same as for ttyS, above. 498 499 If the device connected to the port is not a TTY but a braille 500 device, prepend "brl," before the device type, for instance 501 console=brl,ttyS0 502 For now, only VisioBraille is supported. 503 504 earlycon= [KNL] Output early console device and options. 505 uart[8250],io,<addr>[,options] 506 uart[8250],mmio,<addr>[,options] 507 Start an early, polled-mode console on the 8250/16550 508 UART at the specified I/O port or MMIO address. 509 The options are the same as for ttyS, above. 510 511 no_console_suspend 512 [HW] Never suspend the console 513 Disable suspending of consoles during suspend and 514 hibernate operations. Once disabled, debugging 515 messages can reach various consoles while the rest 516 of the system is being put to sleep (ie, while 517 debugging driver suspend/resume hooks). This may 518 not work reliably with all consoles, but is known 519 to work with serial and VGA consoles. 520 521 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 522 Format: 523 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 524 525 crashkernel=nn[KMG]@ss[KMG] 526 [KNL] Reserve a chunk of physical memory to 527 hold a kernel to switch to with kexec on panic. 528 529 crashkernel=range1:size1[,range2:size2,...][@offset] 530 [KNL] Same as above, but depends on the memory 531 in the running system. The syntax of range is 532 start-[end] where start and end are both 533 a memory unit (amount[KMG]). See also 534 Documentation/kdump/kdump.txt for a example. 535 536 cs4232= [HW,OSS] 537 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq> 538 539 cs89x0_dma= [HW,NET] 540 Format: <dma> 541 542 cs89x0_media= [HW,NET] 543 Format: { rj45 | aui | bnc } 544 545 dasd= [HW,NET] 546 See header of drivers/s390/block/dasd_devmap.c. 547 548 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 549 (one device per port) 550 Format: <port#>,<type> 551 See also Documentation/input/joystick-parport.txt 552 553 debug [KNL] Enable kernel debugging (events log level). 554 555 debug_locks_verbose= 556 [KNL] verbose self-tests 557 Format=<0|1> 558 Print debugging info while doing the locking API 559 self-tests. 560 We default to 0 (no extra messages), setting it to 561 1 will print _a lot_ more information - normally 562 only useful to kernel developers. 563 564 debug_objects [KNL] Enable object debugging 565 566 decnet.addr= [HW,NET] 567 Format: <area>[,<node>] 568 See also Documentation/networking/decnet.txt. 569 570 vt.default_blu= [VT] 571 Format: <blue0>,<blue1>,<blue2>,...,<blue15> 572 Change the default blue palette of the console. 573 This is a 16-member array composed of values 574 ranging from 0-255. 575 576 vt.default_grn= [VT] 577 Format: <green0>,<green1>,<green2>,...,<green15> 578 Change the default green palette of the console. 579 This is a 16-member array composed of values 580 ranging from 0-255. 581 582 vt.default_red= [VT] 583 Format: <red0>,<red1>,<red2>,...,<red15> 584 Change the default red palette of the console. 585 This is a 16-member array composed of values 586 ranging from 0-255. 587 588 vt.default_utf8= 589 [VT] 590 Format=<0|1> 591 Set system-wide default UTF-8 mode for all tty's. 592 Default is 1, i.e. UTF-8 mode is enabled for all 593 newly opened terminals. 594 595 dhash_entries= [KNL] 596 Set number of hash buckets for dentry cache. 597 598 digi= [HW,SERIAL] 599 IO parameters + enable/disable command. 600 601 digiepca= [HW,SERIAL] 602 See drivers/char/README.epca and 603 Documentation/digiepca.txt. 604 605 disable_mtrr_trim [X86, Intel and AMD only] 606 By default the kernel will trim any uncacheable 607 memory out of your available memory pool based on 608 MTRR settings. This parameter disables that behavior, 609 possibly causing your machine to run very slowly. 610 611 dmasound= [HW,OSS] Sound subsystem buffers 612 613 dscc4.setup= [NET] 614 615 dtc3181e= [HW,SCSI] 616 617 earlyprintk= [X86-32,X86-64,SH,BLACKFIN] 618 earlyprintk=vga 619 earlyprintk=serial[,ttySn[,baudrate]] 620 621 Append ",keep" to not disable it when the real console 622 takes over. 623 624 Only vga or serial at a time, not both. 625 626 Currently only ttyS0 and ttyS1 are supported. 627 628 Interaction with the standard serial driver is not 629 very good. 630 631 The VGA output is eventually overwritten by the real 632 console. 633 634 eata= [HW,SCSI] 635 636 edd= [EDD] 637 Format: {"off" | "on" | "skip[mbr]"} 638 639 eisa_irq_edge= [PARISC,HW] 640 See header of drivers/parisc/eisa.c. 641 642 elanfreq= [X86-32] 643 See comment before function elanfreq_setup() in 644 arch/i386/kernel/cpu/cpufreq/elanfreq.c. 645 646 elevator= [IOSCHED] 647 Format: {"anticipatory" | "cfq" | "deadline" | "noop"} 648 See Documentation/block/as-iosched.txt and 649 Documentation/block/deadline-iosched.txt for details. 650 651 elfcorehdr= [X86-32, X86_64] 652 Specifies physical address of start of kernel core 653 image elf header. Generally kexec loader will 654 pass this option to capture kernel. 655 See Documentation/kdump/kdump.txt for details. 656 657 enforcing [SELINUX] Set initial enforcing status. 658 Format: {"0" | "1"} 659 See security/selinux/Kconfig help text. 660 0 -- permissive (log only, no denials). 661 1 -- enforcing (deny and log). 662 Default value is 0. 663 Value can be changed at runtime via /selinux/enforce. 664 665 es1371= [HW,OSS] 666 Format: <spdif>,[<nomix>,[<amplifier>]] 667 See also header of sound/oss/es1371.c. 668 669 ether= [HW,NET] Ethernet cards parameters 670 This option is obsoleted by the "netdev=" option, which 671 has equivalent usage. See its documentation for details. 672 673 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. 674 Format: <io>[,<irq>] 675 676 failslab= 677 fail_page_alloc= 678 fail_make_request=[KNL] 679 General fault injection mechanism. 680 Format: <interval>,<probability>,<space>,<times> 681 See also /Documentation/fault-injection/. 682 683 fd_mcs= [HW,SCSI] 684 See header of drivers/scsi/fd_mcs.c. 685 686 fdomain= [HW,SCSI] 687 See header of drivers/scsi/fdomain.c. 688 689 floppy= [HW] 690 See Documentation/floppy.txt. 691 692 gamecon.map[2|3]= 693 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 694 support via parallel port (up to 5 devices per port) 695 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 696 See also Documentation/input/joystick-parport.txt 697 698 gamma= [HW,DRM] 699 700 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART 701 Format: off | on 702 default: on 703 704 gdth= [HW,SCSI] 705 See header of drivers/scsi/gdth.c. 706 707 gpt [EFI] Forces disk with valid GPT signature but 708 invalid Protective MBR to be treated as GPT. 709 710 gvp11= [HW,SCSI] 711 712 hashdist= [KNL,NUMA] Large hashes allocated during boot 713 are distributed across NUMA nodes. Defaults on 714 for IA-64, off otherwise. 715 Format: 0 | 1 (for off | on) 716 717 hcl= [IA-64] SGI's Hardware Graph compatibility layer 718 719 hd= [EIDE] (E)IDE hard drive subsystem geometry 720 Format: <cyl>,<head>,<sect> 721 722 hd?= [HW] (E)IDE subsystem 723 hd?lun= See Documentation/ide/ide.txt. 724 725 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 726 size of <nn>. This works even on boxes that have no 727 highmem otherwise. This also works to reduce highmem 728 size on bigger boxes. 729 730 highres= [KNL] Enable/disable high resolution timer mode. 731 Valid parameters: "on", "off" 732 Default: "on" 733 734 hisax= [HW,ISDN] 735 See Documentation/isdn/README.HiSax. 736 737 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages. 738 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages. 739 740 i8042.direct [HW] Put keyboard port into non-translated mode 741 i8042.dumbkbd [HW] Pretend that controller can only read data from 742 keyboard and cannot control its state 743 (Don't attempt to blink the leds) 744 i8042.noaux [HW] Don't check for auxiliary (== mouse) port 745 i8042.nokbd [HW] Don't check/create keyboard port 746 i8042.noloop [HW] Disable the AUX Loopback command while probing 747 for the AUX port 748 i8042.nomux [HW] Don't check presence of an active multiplexing 749 controller 750 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 751 controllers 752 i8042.panicblink= 753 [HW] Frequency with which keyboard LEDs should blink 754 when kernel panics (default is 0.5 sec) 755 i8042.reset [HW] Reset the controller during init and cleanup 756 i8042.unlock [HW] Unlock (ignore) the keylock 757 758 i810= [HW,DRM] 759 760 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 761 indicates that the driver is running on unsupported 762 hardware. 763 i8k.force [HW] Activate i8k driver even if SMM BIOS signature 764 does not match list of supported models. 765 i8k.power_status 766 [HW] Report power status in /proc/i8k 767 (disabled by default) 768 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 769 capability is set. 770 771 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter 772 See Documentation/mca.txt. 773 774 icn= [HW,ISDN] 775 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 776 777 ide= [HW] (E)IDE subsystem 778 Format: ide=nodma or ide=doubler 779 See Documentation/ide/ide.txt. 780 781 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed 782 See Documentation/ide/ide.txt. 783 784 idle= [X86] 785 Format: idle=poll or idle=mwait 786 Poll forces a polling idle loop that can slightly improves the performance 787 of waking up a idle CPU, but will use a lot of power and make the system 788 run hot. Not recommended. 789 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose 790 to not use it because it doesn't save as much power as a normal idle 791 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same 792 as idle=poll. 793 794 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 795 Claim all unknown PCI IDE storage controllers. 796 797 ignore_loglevel [KNL] 798 Ignore loglevel setting - this will print /all/ 799 kernel messages to the console. Useful for debugging. 800 801 ihash_entries= [KNL] 802 Set number of hash buckets for inode cache. 803 804 in2000= [HW,SCSI] 805 See header of drivers/scsi/in2000.c. 806 807 init= [KNL] 808 Format: <full_path> 809 Run specified binary instead of /sbin/init as init 810 process. 811 812 initcall_debug [KNL] Trace initcalls as they are executed. Useful 813 for working out where the kernel is dying during 814 startup. 815 816 initrd= [BOOT] Specify the location of the initial ramdisk 817 818 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 819 Format: <irq> 820 821 inttest= [IA64] 822 823 iommu= [x86] 824 off 825 force 826 noforce 827 biomerge 828 panic 829 nopanic 830 merge 831 nomerge 832 forcesac 833 soft 834 835 836 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 837 off 838 Disable intel iommu driver. 839 igfx_off [Default Off] 840 By default, gfx is mapped as normal device. If a gfx 841 device has a dedicated DMAR unit, the DMAR unit is 842 bypassed by not enabling DMAR with this option. In 843 this case, gfx device will use physical address for 844 DMA. 845 forcedac [x86_64] 846 With this option iommu will not optimize to look 847 for io virtual address below 32 bit forcing dual 848 address cycle on pci bus for cards supporting greater 849 than 32 bit addressing. The default is to look 850 for translation below 32 bit and if not available 851 then look in the higher range. 852 strict [Default Off] 853 With this option on every unmap_single operation will 854 result in a hardware IOTLB flush operation as opposed 855 to batching them for performance. 856 857 io_delay= [X86-32,X86-64] I/O delay method 858 0x80 859 Standard port 0x80 based delay 860 0xed 861 Alternate port 0xed based delay (needed on some systems) 862 udelay 863 Simple two microseconds delay 864 none 865 No delay 866 867 io7= [HW] IO7 for Marvel based alpha systems 868 See comment before marvel_specify_io7 in 869 arch/alpha/kernel/core_marvel.c. 870 871 ip= [IP_PNP] 872 See Documentation/filesystems/nfsroot.txt. 873 874 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards 875 See comment before ip2_setup() in 876 drivers/char/ip2/ip2base.c. 877 878 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller 879 See header of drivers/scsi/ips.c. 880 881 ports= [IP_VS_FTP] IPVS ftp helper module 882 Default is 21. 883 Up to 8 (IP_VS_APP_MAX_PORTS) ports 884 may be specified. 885 Format: <port>,<port>.... 886 887 irqfixup [HW] 888 When an interrupt is not handled search all handlers 889 for it. Intended to get systems with badly broken 890 firmware running. 891 892 irqpoll [HW] 893 When an interrupt is not handled search all handlers 894 for it. Also check all handlers each timer 895 interrupt. Intended to get systems with badly broken 896 firmware running. 897 898 isapnp= [ISAPNP] 899 Format: <RDP>,<reset>,<pci_scan>,<verbosity> 900 901 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. 902 Format: 903 <cpu number>,...,<cpu number> 904 or 905 <cpu number>-<cpu number> (must be a positive range in ascending order) 906 or a mixture 907 <cpu number>,...,<cpu number>-<cpu number> 908 This option can be used to specify one or more CPUs 909 to isolate from the general SMP balancing and scheduling 910 algorithms. The only way to move a process onto or off 911 an "isolated" CPU is via the CPU affinity syscalls. 912 <cpu number> begins at 0 and the maximum value is 913 "number of CPUs in system - 1". 914 915 This option is the preferred way to isolate CPUs. The 916 alternative -- manually setting the CPU mask of all 917 tasks in the system -- can cause problems and 918 suboptimal load balancer performance. 919 920 iucv= [HW,NET] 921 922 js= [HW,JOY] Analog joystick 923 See Documentation/input/joystick.txt. 924 925 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 926 specifies the amount of memory usable by the kernel 927 for non-movable allocations. The requested amount is 928 spread evenly throughout all nodes in the system. The 929 remaining memory in each node is used for Movable 930 pages. In the event, a node is too small to have both 931 kernelcore and Movable pages, kernelcore pages will 932 take priority and other nodes will have a larger number 933 of kernelcore pages. The Movable zone is used for the 934 allocation of pages that may be reclaimed or moved 935 by the page migration subsystem. This means that 936 HugeTLB pages may not be allocated from this zone. 937 Note that allocations like PTEs-from-HighMem still 938 use the HighMem zone if it exists, and the Normal 939 zone if it does not. 940 941 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 942 is similar to kernelcore except it specifies the 943 amount of memory used for migratable allocations. 944 If both kernelcore and movablecore is specified, 945 then kernelcore will be at *least* the specified 946 value but may be more. If movablecore on its own 947 is specified, the administrator must be careful 948 that the amount of memory usable for all allocations 949 is not too small. 950 951 keepinitrd [HW,ARM] 952 953 kstack=N [X86-32,X86-64] Print N words from the kernel stack 954 in oops dumps. 955 956 kgdboc= [HW] kgdb over consoles. 957 Requires a tty driver that supports console polling. 958 (only serial suported for now) 959 Format: <serial_device>[,baud] 960 961 l2cr= [PPC] 962 963 l3cr= [PPC] 964 965 lapic [X86-32,APIC] Enable the local APIC even if BIOS 966 disabled it. 967 968 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in 969 C2 power state. 970 971 libata.dma= [LIBATA] DMA control 972 libata.dma=0 Disable all PATA and SATA DMA 973 libata.dma=1 PATA and SATA Disk DMA only 974 libata.dma=2 ATAPI (CDROM) DMA only 975 libata.dma=4 Compact Flash DMA only 976 Combinations also work, so libata.dma=3 enables DMA 977 for disks and CDROMs, but not CFs. 978 979 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 980 when set. 981 Format: <int> 982 983 libata.force= [LIBATA] Force configurations. The format is comma 984 separated list of "[ID:]VAL" where ID is 985 PORT[:DEVICE]. PORT and DEVICE are decimal numbers 986 matching port, link or device. Basically, it matches 987 the ATA ID string printed on console by libata. If 988 the whole ID part is omitted, the last PORT and DEVICE 989 values are used. If ID hasn't been specified yet, the 990 configuration applies to all ports, links and devices. 991 992 If only DEVICE is omitted, the parameter applies to 993 the port and all links and devices behind it. DEVICE 994 number of 0 either selects the first device or the 995 first fan-out link behind PMP device. It does not 996 select the host link. DEVICE number of 15 selects the 997 host link and device attached to it. 998 999 The VAL specifies the configuration to force. As long 1000 as there's no ambiguity shortcut notation is allowed. 1001 For example, both 1.5 and 1.5G would work for 1.5Gbps. 1002 The following configurations can be forced. 1003 1004 * Cable type: 40c, 80c, short40c, unk, ign or sata. 1005 Any ID with matching PORT is used. 1006 1007 * SATA link speed limit: 1.5Gbps or 3.0Gbps. 1008 1009 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 1010 udma[/][16,25,33,44,66,100,133] notation is also 1011 allowed. 1012 1013 * [no]ncq: Turn on or off NCQ. 1014 1015 If there are multiple matching configurations changing 1016 the same attribute, the last one is used. 1017 1018 load_ramdisk= [RAM] List of ramdisks to load from floppy 1019 See Documentation/ramdisk.txt. 1020 1021 lockd.nlm_grace_period=P [NFS] Assign grace period. 1022 Format: <integer> 1023 1024 lockd.nlm_tcpport=N [NFS] Assign TCP port. 1025 Format: <integer> 1026 1027 lockd.nlm_timeout=T [NFS] Assign timeout value. 1028 Format: <integer> 1029 1030 lockd.nlm_udpport=M [NFS] Assign UDP port. 1031 Format: <integer> 1032 1033 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 1034 Format: <irq> 1035 1036 loglevel= All Kernel Messages with a loglevel smaller than the 1037 console loglevel will be printed to the console. It can 1038 also be changed with klogd or other programs. The 1039 loglevels are defined as follows: 1040 1041 0 (KERN_EMERG) system is unusable 1042 1 (KERN_ALERT) action must be taken immediately 1043 2 (KERN_CRIT) critical conditions 1044 3 (KERN_ERR) error conditions 1045 4 (KERN_WARNING) warning conditions 1046 5 (KERN_NOTICE) normal but significant condition 1047 6 (KERN_INFO) informational 1048 7 (KERN_DEBUG) debug-level messages 1049 1050 log_buf_len=n Sets the size of the printk ring buffer, in bytes. 1051 Format: { n | nk | nM } 1052 n must be a power of two. The default size 1053 is set in the kernel config file. 1054 1055 logo.nologo [FB] Disables display of the built-in Linux logo. 1056 This may be used to provide more screen space for 1057 kernel log messages and is useful when debugging 1058 kernel boot problems. 1059 1060 lp=0 [LP] Specify parallel ports to use, e.g, 1061 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 1062 lp=reset first parallel port). 'lp=0' disables the 1063 lp=auto printer driver. 'lp=reset' (which can be 1064 specified in addition to the ports) causes 1065 attached printers to be reset. Using 1066 lp=port1,port2,... specifies the parallel ports 1067 to associate lp devices with, starting with 1068 lp0. A port specification may be 'none' to skip 1069 that lp device, or a parport name such as 1070 'parport0'. Specifying 'lp=auto' instead of a 1071 port specification list means that device IDs 1072 from each port should be examined, to see if 1073 an IEEE 1284-compliant printer is attached; if 1074 so, the driver will manage that printer. 1075 See also header of drivers/char/lp.c. 1076 1077 lpj=n [KNL] 1078 Sets loops_per_jiffy to given constant, thus avoiding 1079 time-consuming boot-time autodetection (up to 250 ms per 1080 CPU). 0 enables autodetection (default). To determine 1081 the correct value for your kernel, boot with normal 1082 autodetection and see what value is printed. Note that 1083 on SMP systems the preset will be applied to all CPUs, 1084 which is likely to cause problems if your CPUs need 1085 significantly divergent settings. An incorrect value 1086 will cause delays in the kernel to be wrong, leading to 1087 unpredictable I/O errors and other breakage. Although 1088 unlikely, in the extreme case this might damage your 1089 hardware. 1090 1091 ltpc= [NET] 1092 Format: <io>,<irq>,<dma> 1093 1094 mac5380= [HW,SCSI] Format: 1095 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> 1096 1097 mac53c9x= [HW,SCSI] Format: 1098 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> 1099 1100 machvec= [IA64] Force the use of a particular machine-vector 1101 (machvec) in a generic kernel. 1102 Example: machvec=hpzx1_swiotlb 1103 1104 max_loop= [LOOP] Maximum number of loopback devices that can 1105 be mounted 1106 Format: <1-256> 1107 1108 maxcpus= [SMP] Maximum number of processors that an SMP kernel 1109 should make use of. maxcpus=n : n >= 0 limits the 1110 kernel to using 'n' processors. n=0 is a special case, 1111 it is equivalent to "nosmp", which also disables 1112 the IO APIC. 1113 1114 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or 1115 equal to this physical address is ignored. 1116 1117 max_luns= [SCSI] Maximum number of LUNs to probe. 1118 Should be between 1 and 2^32-1. 1119 1120 max_report_luns= 1121 [SCSI] Maximum number of LUNs received. 1122 Should be between 1 and 16384. 1123 1124 mcatest= [IA-64] 1125 1126 mce [X86-32] Machine Check Exception 1127 1128 mce=option [X86-64] See Documentation/x86_64/boot-options.txt 1129 1130 md= [HW] RAID subsystems devices and level 1131 See Documentation/md.txt. 1132 1133 mdacon= [MDA] 1134 Format: <first>,<last> 1135 Specifies range of consoles to be captured by the MDA. 1136 1137 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 1138 Amount of memory to be used when the kernel is not able 1139 to see the whole system memory or for test. 1140 [X86-32] Use together with memmap= to avoid physical 1141 address space collisions. Without memmap= PCI devices 1142 could be placed at addresses belonging to unused RAM. 1143 1144 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 1145 memory. 1146 1147 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact 1148 E820 memory map, as specified by the user. 1149 Such memmap=exactmap lines can be constructed based on 1150 BIOS output or other requirements. See the memmap=nn@ss 1151 option description. 1152 1153 memmap=nn[KMG]@ss[KMG] 1154 [KNL] Force usage of a specific region of memory 1155 Region of memory to be used, from ss to ss+nn. 1156 1157 memmap=nn[KMG]#ss[KMG] 1158 [KNL,ACPI] Mark specific memory as ACPI data. 1159 Region of memory to be used, from ss to ss+nn. 1160 1161 memmap=nn[KMG]$ss[KMG] 1162 [KNL,ACPI] Mark specific memory as reserved. 1163 Region of memory to be used, from ss to ss+nn. 1164 Example: Exclude memory from 0x18690000-0x1869ffff 1165 memmap=64K$0x18690000 1166 or 1167 memmap=0x10000$0x18690000 1168 1169 memtest= [KNL,X86_64] Enable memtest 1170 Format: <integer> 1171 range: 0,4 : pattern number 1172 default : 0 <disable> 1173 1174 meye.*= [HW] Set MotionEye Camera parameters 1175 See Documentation/video4linux/meye.txt. 1176 1177 mfgpt_irq= [IA-32] Specify the IRQ to use for the 1178 Multi-Function General Purpose Timers on AMD Geode 1179 platforms. 1180 1181 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when 1182 the BIOS has incorrectly applied a workaround. TinyBIOS 1183 version 0.98 is known to be affected, 0.99 fixes the 1184 problem by letting the user disable the workaround. 1185 1186 mga= [HW,DRM] 1187 1188 mousedev.tap_time= 1189 [MOUSE] Maximum time between finger touching and 1190 leaving touchpad surface for touch to be considered 1191 a tap and be reported as a left button click (for 1192 touchpads working in absolute mode only). 1193 Format: <msecs> 1194 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 1195 reporting absolute coordinates, such as tablets 1196 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 1197 reporting absolute coordinates, such as tablets 1198 1199 mpu401= [HW,OSS] 1200 Format: <io>,<irq> 1201 1202 MTD_Partition= [MTD] 1203 Format: <name>,<region-number>,<size>,<offset> 1204 1205 MTD_Region= [MTD] Format: 1206 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 1207 1208 mtdparts= [MTD] 1209 See drivers/mtd/cmdlinepart.c. 1210 1211 mtouchusb.raw_coordinates= 1212 [HW] Make the MicroTouch USB driver use raw coordinates 1213 ('y', default) or cooked coordinates ('n') 1214 1215 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 1216 1217 NCR_D700= [HW,SCSI] 1218 See header of drivers/scsi/NCR_D700.c. 1219 1220 ncr5380= [HW,SCSI] 1221 1222 ncr53c400= [HW,SCSI] 1223 1224 ncr53c400a= [HW,SCSI] 1225 1226 ncr53c406a= [HW,SCSI] 1227 1228 ncr53c8xx= [HW,SCSI] 1229 1230 netdev= [NET] Network devices parameters 1231 Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 1232 Note that mem_start is often overloaded to mean 1233 something different and driver-specific. 1234 This usage is only documented in each driver source 1235 file if at all. 1236 1237 nfsaddrs= [NFS] 1238 See Documentation/filesystems/nfsroot.txt. 1239 1240 nfsroot= [NFS] nfs root filesystem for disk-less boxes. 1241 See Documentation/filesystems/nfsroot.txt. 1242 1243 nfs.callback_tcpport= 1244 [NFS] set the TCP port on which the NFSv4 callback 1245 channel should listen. 1246 1247 nfs.idmap_cache_timeout= 1248 [NFS] set the maximum lifetime for idmapper cache 1249 entries. 1250 1251 nfs.enable_ino64= 1252 [NFS] enable 64-bit inode numbers. 1253 If zero, the NFS client will fake up a 32-bit inode 1254 number for the readdir() and stat() syscalls instead 1255 of returning the full 64-bit number. 1256 The default is to return 64-bit inode numbers. 1257 1258 nmi_debug= [KNL,AVR32] Specify one or more actions to take 1259 when a NMI is triggered. 1260 Format: [state][,regs][,debounce][,die] 1261 1262 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels 1263 1264 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths 1265 emulation library even if a 387 maths coprocessor 1266 is present. 1267 1268 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien 1269 caches in the slab allocator. Saves per-node memory, 1270 but will impact performance. 1271 1272 noalign [KNL,ARM] 1273 1274 noapic [SMP,APIC] Tells the kernel to not make use of any 1275 IOAPICs that may be present in the system. 1276 1277 nobats [PPC] Do not use BATs for mapping kernel lowmem 1278 on "Classic" PPC cores. 1279 1280 nocache [ARM] 1281 1282 nodelayacct [KNL] Disable per-task delay accounting 1283 1284 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. 1285 1286 noefi [X86-32,X86-64] Disable EFI runtime services support. 1287 1288 noexec [IA-64] 1289 1290 noexec [X86-32,X86-64] 1291 On X86-32 available only on PAE configured kernels. 1292 noexec=on: enable non-executable mappings (default) 1293 noexec=off: disable non-executable mappings 1294 1295 noexec32 [X86-64] 1296 This affects only 32-bit executables. 1297 noexec32=on: enable non-executable mappings (default) 1298 read doesn't imply executable mappings 1299 noexec32=off: disable non-executable mappings 1300 read implies executable mappings 1301 1302 nofxsr [BUGS=X86-32] Disables x86 floating point extended 1303 register save and restore. The kernel will only save 1304 legacy floating-point registers on task switch. 1305 1306 noclflush [BUGS=X86] Don't use the CLFLUSH instruction 1307 1308 nohlt [BUGS=ARM] 1309 1310 no-hlt [BUGS=X86-32] Tells the kernel that the hlt 1311 instruction doesn't work correctly and not to 1312 use it. 1313 1314 nohalt [IA-64] Tells the kernel not to use the power saving 1315 function PAL_HALT_LIGHT when idle. This increases 1316 power-consumption. On the positive side, it reduces 1317 interrupt wake-up latency, which may improve performance 1318 in certain environments such as networked servers or 1319 real-time systems. 1320 1321 nohz= [KNL] Boottime enable/disable dynamic ticks 1322 Valid arguments: on, off 1323 Default: on 1324 1325 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing 1326 1327 noirqdebug [X86-32] Disables the code which attempts to detect and 1328 disable unhandled interrupt sources. 1329 1330 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for 1331 broken timer IRQ sources. 1332 1333 noisapnp [ISAPNP] Disables ISA PnP code. 1334 1335 noinitrd [RAM] Tells the kernel not to load any configured 1336 initial RAM disk. 1337 1338 nointroute [IA-64] 1339 1340 nojitter [IA64] Disables jitter checking for ITC timers. 1341 1342 nolapic [X86-32,APIC] Do not enable or use the local APIC. 1343 1344 nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 1345 1346 noltlbs [PPC] Do not use large page/tlb entries for kernel 1347 lowmem mapping on PPC40x. 1348 1349 nomca [IA-64] Disable machine check abort handling 1350 1351 nomce [X86-32] Machine Check Exception 1352 1353 nomfgpt [X86-32] Disable Multi-Function General Purpose 1354 Timer usage (for AMD Geode machines). 1355 1356 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops 1357 1358 noreplace-smp [X86-32,SMP] Don't replace SMP instructions 1359 with UP alternatives 1360 1361 noresidual [PPC] Don't use residual data on PReP machines. 1362 1363 noresume [SWSUSP] Disables resume and restores original swap 1364 space. 1365 1366 no-scroll [VGA] Disables scrollback. 1367 This is required for the Braillex ib80-piezo Braille 1368 reader made by F.H. Papenmeier (Germany). 1369 1370 nosbagart [IA-64] 1371 1372 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. 1373 1374 nosmp [SMP] Tells an SMP kernel to act as a UP kernel, 1375 and disable the IO APIC. legacy for "maxcpus=0". 1376 1377 nosoftlockup [KNL] Disable the soft-lockup detector. 1378 1379 nosync [HW,M68K] Disables sync negotiation for all devices. 1380 1381 notsc [BUGS=X86-32] Disable Time Stamp Counter 1382 1383 nousb [USB] Disable the USB subsystem 1384 1385 nowb [ARM] 1386 1387 nptcg= [IA64] Override max number of concurrent global TLB 1388 purges which is reported from either PAL_VM_SUMMARY or 1389 SAL PALO. 1390 1391 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 1392 one of ['zone', 'node', 'default'] can be specified 1393 This can be set from sysctl after boot. 1394 See Documentation/sysctl/vm.txt for details. 1395 1396 nr_uarts= [SERIAL] maximum number of UARTs to be registered. 1397 1398 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands 1399 Rather than timing out after 20 ms if an EC 1400 command is not properly ACKed, override the length 1401 of the timeout. We have interrupts disabled while 1402 waiting for the ACK, so if this is set too high 1403 interrupts *may* be lost! 1404 1405 opl3= [HW,OSS] 1406 Format: <io> 1407 1408 oprofile.timer= [HW] 1409 Use timer interrupt instead of performance counters 1410 1411 osst= [HW,SCSI] SCSI Tape Driver 1412 Format: <buffer_size>,<write_threshold> 1413 See also Documentation/scsi/st.txt. 1414 1415 panic= [KNL] Kernel behaviour on panic 1416 Format: <timeout> 1417 1418 parkbd.port= [HW] Parallel port number the keyboard adapter is 1419 connected to, default is 0. 1420 Format: <parport#> 1421 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 1422 0 for XT, 1 for AT (default is AT). 1423 Format: <mode> 1424 1425 parport= [HW,PPT] Specify parallel ports. 0 disables. 1426 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 1427 Use 'auto' to force the driver to use any 1428 IRQ/DMA settings detected (the default is to 1429 ignore detected IRQ/DMA settings because of 1430 possible conflicts). You can specify the base 1431 address, IRQ, and DMA settings; IRQ and DMA 1432 should be numbers, or 'auto' (for using detected 1433 settings on that particular port), or 'nofifo' 1434 (to avoid using a FIFO even if it is detected). 1435 Parallel ports are assigned in the order they 1436 are specified on the command line, starting 1437 with parport0. 1438 1439 parport_init_mode= [HW,PPT] 1440 Configure VIA parallel port to operate in 1441 a specific mode. This is necessary on Pegasos 1442 computer where firmware has no options for setting 1443 up parallel port mode and sets it to spp. 1444 Currently this function knows 686a and 8231 chips. 1445 Format: [spp|ps2|epp|ecp|ecpepp] 1446 1447 pas2= [HW,OSS] Format: 1448 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16> 1449 1450 pas16= [HW,SCSI] 1451 See header of drivers/scsi/pas16.c. 1452 1453 pause_on_oops= 1454 Halt all CPUs after the first oops has been printed for 1455 the specified number of seconds. This is to be used if 1456 your oopses keep scrolling off the screen. 1457 1458 pcbit= [HW,ISDN] 1459 1460 pcd. [PARIDE] 1461 See header of drivers/block/paride/pcd.c. 1462 See also Documentation/paride.txt. 1463 1464 pci=option[,option...] [PCI] various PCI subsystem options: 1465 off [X86-32] don't probe for the PCI bus 1466 bios [X86-32] force use of PCI BIOS, don't access 1467 the hardware directly. Use this if your machine 1468 has a non-standard PCI host bridge. 1469 nobios [X86-32] disallow use of PCI BIOS, only direct 1470 hardware access methods are allowed. Use this 1471 if you experience crashes upon bootup and you 1472 suspect they are caused by the BIOS. 1473 conf1 [X86-32] Force use of PCI Configuration 1474 Mechanism 1. 1475 conf2 [X86-32] Force use of PCI Configuration 1476 Mechanism 2. 1477 noaer [PCIE] If the PCIEAER kernel config parameter is 1478 enabled, this kernel boot option can be used to 1479 disable the use of PCIE advanced error reporting. 1480 nodomains [PCI] Disable support for multiple PCI 1481 root domains (aka PCI segments, in ACPI-speak). 1482 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI 1483 Configuration 1484 nomsi [MSI] If the PCI_MSI kernel config parameter is 1485 enabled, this kernel boot option can be used to 1486 disable the use of MSI interrupts system-wide. 1487 biosirq [X86-32] Use PCI BIOS calls to get the interrupt 1488 routing table. These calls are known to be buggy 1489 on several machines and they hang the machine 1490 when used, but on other computers it's the only 1491 way to get the interrupt routing table. Try 1492 this option if the kernel is unable to allocate 1493 IRQs or discover secondary PCI buses on your 1494 motherboard. 1495 rom [X86-32] Assign address space to expansion ROMs. 1496 Use with caution as certain devices share 1497 address decoders between ROMs and other 1498 resources. 1499 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be 1500 assigned automatically to PCI devices. You can 1501 make the kernel exclude IRQs of your ISA cards 1502 this way. 1503 pirqaddr=0xAAAAA [X86-32] Specify the physical address 1504 of the PIRQ table (normally generated 1505 by the BIOS) if it is outside the 1506 F0000h-100000h range. 1507 lastbus=N [X86-32] Scan all buses thru bus #N. Can be 1508 useful if the kernel is unable to find your 1509 secondary buses and you want to tell it 1510 explicitly which ones they are. 1511 assign-busses [X86-32] Always assign all PCI bus 1512 numbers ourselves, overriding 1513 whatever the firmware may have done. 1514 usepirqmask [X86-32] Honor the possible IRQ mask stored 1515 in the BIOS $PIR table. This is needed on 1516 some systems with broken BIOSes, notably 1517 some HP Pavilion N5400 and Omnibook XE3 1518 notebooks. This will have no effect if ACPI 1519 IRQ routing is enabled. 1520 noacpi [X86-32] Do not use ACPI for IRQ routing 1521 or for PCI scanning. 1522 use_crs [X86-32] Use _CRS for PCI resource 1523 allocation. 1524 routeirq Do IRQ routing for all PCI devices. 1525 This is normally done in pci_enable_device(), 1526 so this option is a temporary workaround 1527 for broken drivers that don't call it. 1528 firmware [ARM] Do not re-enumerate the bus but instead 1529 just use the configuration from the 1530 bootloader. This is currently used on 1531 IXP2000 systems where the bus has to be 1532 configured a certain way for adjunct CPUs. 1533 noearly [X86] Don't do any early type 1 scanning. 1534 This might help on some broken boards which 1535 machine check when some devices' config space 1536 is read. But various workarounds are disabled 1537 and some IOMMU drivers will not work. 1538 bfsort Sort PCI devices into breadth-first order. 1539 This sorting is done to get a device 1540 order compatible with older (<= 2.4) kernels. 1541 nobfsort Don't sort PCI devices into breadth-first order. 1542 cbiosize=nn[KMG] The fixed amount of bus space which is 1543 reserved for the CardBus bridge's IO window. 1544 The default value is 256 bytes. 1545 cbmemsize=nn[KMG] The fixed amount of bus space which is 1546 reserved for the CardBus bridge's memory 1547 window. The default value is 64 megabytes. 1548 1549 pcmv= [HW,PCMCIA] BadgePAD 4 1550 1551 pd. [PARIDE] 1552 See Documentation/paride.txt. 1553 1554 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 1555 boot time. 1556 Format: { 0 | 1 } 1557 See arch/parisc/kernel/pdc_chassis.c 1558 1559 pf. [PARIDE] 1560 See Documentation/paride.txt. 1561 1562 pg. [PARIDE] 1563 See Documentation/paride.txt. 1564 1565 pirq= [SMP,APIC] Manual mp-table setup 1566 See Documentation/i386/IO-APIC.txt. 1567 1568 plip= [PPT,NET] Parallel port network link 1569 Format: { parport<nr> | timid | 0 } 1570 See also Documentation/parport.txt. 1571 1572 pnpacpi= [ACPI] 1573 { off } 1574 1575 pnpbios= [ISAPNP] 1576 { on | off | curr | res | no-curr | no-res } 1577 1578 pnp_reserve_irq= 1579 [ISAPNP] Exclude IRQs for the autoconfiguration 1580 1581 pnp_reserve_dma= 1582 [ISAPNP] Exclude DMAs for the autoconfiguration 1583 1584 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 1585 Ranges are in pairs (I/O port base and size). 1586 1587 pnp_reserve_mem= 1588 [ISAPNP] Exclude memory regions for the 1589 autoconfiguration. 1590 Ranges are in pairs (memory base and size). 1591 1592 print-fatal-signals= 1593 [KNL] debug: print fatal signals 1594 print-fatal-signals=1: print segfault info to 1595 the kernel console. 1596 default: off. 1597 1598 printk.time= Show timing data prefixed to each printk message line 1599 Format: <bool> (1/Y/y=enable, 0/N/n=disable) 1600 1601 profile= [KNL] Enable kernel profiling via /proc/profile 1602 Format: [schedule,]<number> 1603 Param: "schedule" - profile schedule points. 1604 Param: <number> - step/bucket size as a power of 2 for 1605 statistical time based profiling. 1606 Param: "sleep" - profile D-state sleeping (millisecs). 1607 Requires CONFIG_SCHEDSTATS 1608 Param: "kvm" - profile VM exits. 1609 1610 processor.max_cstate= [HW,ACPI] 1611 Limit processor to maximum C-state 1612 max_cstate=9 overrides any DMI blacklist limit. 1613 1614 processor.nocst [HW,ACPI] 1615 Ignore the _CST method to determine C-states, 1616 instead using the legacy FADT method 1617 1618 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 1619 before loading. 1620 See Documentation/ramdisk.txt. 1621 1622 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 1623 probe for; one of (bare|imps|exps|lifebook|any). 1624 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 1625 per second. 1626 psmouse.resetafter= [HW,MOUSE] 1627 Try to reset the device after so many bad packets 1628 (0 = never). 1629 psmouse.resolution= 1630 [HW,MOUSE] Set desired mouse resolution, in dpi. 1631 psmouse.smartscroll= 1632 [HW,MOUSE] Controls Logitech smartscroll autorepeat. 1633 0 = disabled, 1 = enabled (default). 1634 1635 pss= [HW,OSS] Personal Sound System (ECHO ESC614) 1636 Format: 1637 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> 1638 1639 pt. [PARIDE] 1640 See Documentation/paride.txt. 1641 1642 pty.legacy_count= 1643 [KNL] Number of legacy pty's. Overwrites compiled-in 1644 default number. 1645 1646 quiet [KNL] Disable most log messages 1647 1648 r128= [HW,DRM] 1649 1650 raid= [HW,RAID] 1651 See Documentation/md.txt. 1652 1653 ramdisk_blocksize= [RAM] 1654 See Documentation/ramdisk.txt. 1655 1656 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 1657 See Documentation/ramdisk.txt. 1658 1659 rcupdate.blimit= [KNL,BOOT] 1660 Set maximum number of finished RCU callbacks to process 1661 in one batch. 1662 1663 rcupdate.qhimark= [KNL,BOOT] 1664 Set threshold of queued 1665 RCU callbacks over which batch limiting is disabled. 1666 1667 rcupdate.qlowmark= [KNL,BOOT] 1668 Set threshold of queued RCU callbacks below which 1669 batch limiting is re-enabled. 1670 1671 rdinit= [KNL] 1672 Format: <full_path> 1673 Run specified binary instead of /init from the ramdisk, 1674 used for early userspace startup. See initrd. 1675 1676 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode 1677 Format: <reboot_mode>[,<reboot_mode2>[,...]] 1678 See arch/*/kernel/reboot.c or arch/*/kernel/process.c 1679 1680 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area 1681 1682 reservetop= [X86-32] 1683 Format: nn[KMG] 1684 Reserves a hole at the top of the kernel virtual 1685 address space. 1686 1687 reset_devices [KNL] Force drivers to reset the underlying device 1688 during initialization. 1689 1690 resume= [SWSUSP] 1691 Specify the partition device for software suspend 1692 1693 resume_offset= [SWSUSP] 1694 Specify the offset from the beginning of the partition 1695 given by "resume=" at which the swap header is located, 1696 in <PAGE_SIZE> units (needed only for swap files). 1697 See Documentation/power/swsusp-and-swap-files.txt 1698 1699 retain_initrd [RAM] Keep initrd memory after extraction 1700 1701 rhash_entries= [KNL,NET] 1702 Set number of hash buckets for route cache 1703 1704 riscom8= [HW,SERIAL] 1705 Format: <io_board1>[,<io_board2>[,...<io_boardN>]] 1706 1707 ro [KNL] Mount root device read-only on boot 1708 1709 root= [KNL] Root filesystem 1710 1711 rootdelay= [KNL] Delay (in seconds) to pause before attempting to 1712 mount the root filesystem 1713 1714 rootflags= [KNL] Set root filesystem mount option string 1715 1716 rootfstype= [KNL] Set root filesystem type 1717 1718 rootwait [KNL] Wait (indefinitely) for root device to show up. 1719 Useful for devices that are detected asynchronously 1720 (e.g. USB and MMC devices). 1721 1722 root_plug.vendor_id= 1723 [ROOTPLUG] Override the default vendor ID 1724 1725 root_plug.product_id= 1726 [ROOTPLUG] Override the default product ID 1727 1728 root_plug.debug= 1729 [ROOTPLUG] Enable debugging output 1730 1731 rw [KNL] Mount root device read-write on boot 1732 1733 S [KNL] Run init in single mode 1734 1735 sa1100ir [NET] 1736 See drivers/net/irda/sa1100_ir.c. 1737 1738 sbni= [NET] Granch SBNI12 leased line adapter 1739 1740 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver 1741 Format: <io>[,<timeout>[,<isapnp>]] 1742 1743 scsi_debug_*= [SCSI] 1744 See drivers/scsi/scsi_debug.c. 1745 1746 scsi_default_dev_flags= 1747 [SCSI] SCSI default device flags 1748 Format: <integer> 1749 1750 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model 1751 Format: <vendor>:<model>:<flags> 1752 (flags are integer value) 1753 1754 scsi_logging_level= [SCSI] a bit mask of logging levels 1755 See drivers/scsi/scsi_logging.h for bits. Also 1756 settable via sysctl at dev.scsi.logging_level 1757 (/proc/sys/dev/scsi/logging_level). 1758 There is also a nice 'scsi_logging_level' script in the 1759 S390-tools package, available for download at 1760 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html 1761 1762 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are 1763 discovered. async scans them in kernel threads, 1764 allowing boot to proceed. none ignores them, expecting 1765 user space to do the scan. 1766 1767 selinux [SELINUX] Disable or enable SELinux at boot time. 1768 Format: { "0" | "1" } 1769 See security/selinux/Kconfig help text. 1770 0 -- disable. 1771 1 -- enable. 1772 Default value is set via kernel config option. 1773 If enabled at boot time, /selinux/disable can be used 1774 later to disable prior to initial policy load. 1775 1776 selinux_compat_net = 1777 [SELINUX] Set initial selinux_compat_net flag value. 1778 Format: { "0" | "1" } 1779 0 -- use new secmark-based packet controls 1780 1 -- use legacy packet controls 1781 Default value is 0 (preferred). 1782 Value can be changed at runtime via 1783 /selinux/compat_net. 1784 1785 serialnumber [BUGS=X86-32] 1786 1787 shapers= [NET] 1788 Maximal number of shapers. 1789 1790 sim710= [SCSI,HW] 1791 See header of drivers/scsi/sim710.c. 1792 1793 simeth= [IA-64] 1794 simscsi= 1795 1796 slram= [HW,MTD] 1797 1798 slub_debug[=options[,slabs]] [MM, SLUB] 1799 Enabling slub_debug allows one to determine the 1800 culprit if slab objects become corrupted. Enabling 1801 slub_debug can create guard zones around objects and 1802 may poison objects when not in use. Also tracks the 1803 last alloc / free. For more information see 1804 Documentation/vm/slub.txt. 1805 1806 slub_max_order= [MM, SLUB] 1807 Determines the maximum allowed order for slabs. 1808 A high setting may cause OOMs due to memory 1809 fragmentation. For more information see 1810 Documentation/vm/slub.txt. 1811 1812 slub_min_objects= [MM, SLUB] 1813 The minimum number of objects per slab. SLUB will 1814 increase the slab order up to slub_max_order to 1815 generate a sufficiently large slab able to contain 1816 the number of objects indicated. The higher the number 1817 of objects the smaller the overhead of tracking slabs 1818 and the less frequently locks need to be acquired. 1819 For more information see Documentation/vm/slub.txt. 1820 1821 slub_min_order= [MM, SLUB] 1822 Determines the mininum page order for slabs. Must be 1823 lower than slub_max_order. 1824 For more information see Documentation/vm/slub.txt. 1825 1826 slub_nomerge [MM, SLUB] 1827 Disable merging of slabs with similar size. May be 1828 necessary if there is some reason to distinguish 1829 allocs to different slabs. Debug options disable 1830 merging on their own. 1831 For more information see Documentation/vm/slub.txt. 1832 1833 smart2= [HW] 1834 Format: <io1>[,<io2>[,...,<io8>]] 1835 1836 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only 1837 attempt to substitute SMP alternatives once at boot. 1838 1839 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 1840 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 1841 smsc-ircc2.ircc_sir= [HW] SIR base I/O port 1842 smsc-ircc2.ircc_fir= [HW] FIR base I/O port 1843 smsc-ircc2.ircc_irq= [HW] IRQ line 1844 smsc-ircc2.ircc_dma= [HW] DMA channel 1845 smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 1846 0: Toshiba Satellite 1800 (GP data pin select) 1847 1: Fast pin select (default) 1848 2: ATC IRMode 1849 1850 snd-ad1816a= [HW,ALSA] 1851 1852 snd-ad1848= [HW,ALSA] 1853 1854 snd-ali5451= [HW,ALSA] 1855 1856 snd-als100= [HW,ALSA] 1857 1858 snd-als4000= [HW,ALSA] 1859 1860 snd-azt2320= [HW,ALSA] 1861 1862 snd-cmi8330= [HW,ALSA] 1863 1864 snd-cmipci= [HW,ALSA] 1865 1866 snd-cs4231= [HW,ALSA] 1867 1868 snd-cs4232= [HW,ALSA] 1869 1870 snd-cs4236= [HW,ALSA] 1871 1872 snd-cs4281= [HW,ALSA] 1873 1874 snd-cs46xx= [HW,ALSA] 1875 1876 snd-dt019x= [HW,ALSA] 1877 1878 snd-dummy= [HW,ALSA] 1879 1880 snd-emu10k1= [HW,ALSA] 1881 1882 snd-ens1370= [HW,ALSA] 1883 1884 snd-ens1371= [HW,ALSA] 1885 1886 snd-es968= [HW,ALSA] 1887 1888 snd-es1688= [HW,ALSA] 1889 1890 snd-es18xx= [HW,ALSA] 1891 1892 snd-es1938= [HW,ALSA] 1893 1894 snd-es1968= [HW,ALSA] 1895 1896 snd-fm801= [HW,ALSA] 1897 1898 snd-gusclassic= [HW,ALSA] 1899 1900 snd-gusextreme= [HW,ALSA] 1901 1902 snd-gusmax= [HW,ALSA] 1903 1904 snd-hdsp= [HW,ALSA] 1905 1906 snd-ice1712= [HW,ALSA] 1907 1908 snd-intel8x0= [HW,ALSA] 1909 1910 snd-interwave= [HW,ALSA] 1911 1912 snd-interwave-stb= 1913 [HW,ALSA] 1914 1915 snd-korg1212= [HW,ALSA] 1916 1917 snd-maestro3= [HW,ALSA] 1918 1919 snd-mpu401= [HW,ALSA] 1920 1921 snd-mtpav= [HW,ALSA] 1922 1923 snd-nm256= [HW,ALSA] 1924 1925 snd-opl3sa2= [HW,ALSA] 1926 1927 snd-opti92x-ad1848= 1928 [HW,ALSA] 1929 1930 snd-opti92x-cs4231= 1931 [HW,ALSA] 1932 1933 snd-opti93x= [HW,ALSA] 1934 1935 snd-pmac= [HW,ALSA] 1936 1937 snd-rme32= [HW,ALSA] 1938 1939 snd-rme96= [HW,ALSA] 1940 1941 snd-rme9652= [HW,ALSA] 1942 1943 snd-sb8= [HW,ALSA] 1944 1945 snd-sb16= [HW,ALSA] 1946 1947 snd-sbawe= [HW,ALSA] 1948 1949 snd-serial= [HW,ALSA] 1950 1951 snd-sgalaxy= [HW,ALSA] 1952 1953 snd-sonicvibes= [HW,ALSA] 1954 1955 snd-sun-amd7930= 1956 [HW,ALSA] 1957 1958 snd-sun-cs4231= [HW,ALSA] 1959 1960 snd-trident= [HW,ALSA] 1961 1962 snd-usb-audio= [HW,ALSA,USB] 1963 1964 snd-via82xx= [HW,ALSA] 1965 1966 snd-virmidi= [HW,ALSA] 1967 1968 snd-wavefront= [HW,ALSA] 1969 1970 snd-ymfpci= [HW,ALSA] 1971 1972 sonypi.*= [HW] Sony Programmable I/O Control Device driver 1973 See Documentation/sonypi.txt 1974 1975 specialix= [HW,SERIAL] Specialix multi-serial port adapter 1976 See Documentation/specialix.txt. 1977 1978 spia_io_base= [HW,MTD] 1979 spia_fio_base= 1980 spia_pedr= 1981 spia_peddr= 1982 1983 sscape= [HW,OSS] 1984 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq> 1985 1986 st= [HW,SCSI] SCSI tape parameters (buffers, etc.) 1987 See Documentation/scsi/st.txt. 1988 1989 sti= [PARISC,HW] 1990 Format: <num> 1991 Set the STI (builtin display/keyboard on the HP-PARISC 1992 machines) console (graphic card) which should be used 1993 as the initial boot-console. 1994 See also comment in drivers/video/console/sticore.c. 1995 1996 sti_font= [HW] 1997 See comment in drivers/video/console/sticore.c. 1998 1999 stifb= [HW] 2000 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 2001 2002 sunrpc.pool_mode= 2003 [NFS] 2004 Control how the NFS server code allocates CPUs to 2005 service thread pools. Depending on how many NICs 2006 you have and where their interrupts are bound, this 2007 option will affect which CPUs will do NFS serving. 2008 Note: this parameter cannot be changed while the 2009 NFS server is running. 2010 2011 auto the server chooses an appropriate mode 2012 automatically using heuristics 2013 global a single global pool contains all CPUs 2014 percpu one pool for each CPU 2015 pernode one pool for each NUMA node (equivalent 2016 to global on non-NUMA machines) 2017 2018 swiotlb= [IA-64] Number of I/O TLB slabs 2019 2020 switches= [HW,M68k] 2021 2022 sym53c416= [HW,SCSI] 2023 See header of drivers/scsi/sym53c416.c. 2024 2025 sysrq_always_enabled 2026 [KNL] 2027 Ignore sysrq setting - this boot parameter will 2028 neutralize any effect of /proc/sys/kernel/sysrq. 2029 Useful for debugging. 2030 2031 t128= [HW,SCSI] 2032 See header of drivers/scsi/t128.c. 2033 2034 tdfx= [HW,DRM] 2035 2036 thash_entries= [KNL,NET] 2037 Set number of hash buckets for TCP connection 2038 2039 thermal.act= [HW,ACPI] 2040 -1: disable all active trip points in all thermal zones 2041 <degrees C>: override all lowest active trip points 2042 2043 thermal.crt= [HW,ACPI] 2044 -1: disable all critical trip points in all thermal zones 2045 <degrees C>: lower all critical trip points 2046 2047 thermal.nocrt= [HW,ACPI] 2048 Set to disable actions on ACPI thermal zone 2049 critical and hot trip points. 2050 2051 thermal.off= [HW,ACPI] 2052 1: disable ACPI thermal control 2053 2054 thermal.psv= [HW,ACPI] 2055 -1: disable all passive trip points 2056 <degrees C>: override all passive trip points to this value 2057 2058 thermal.tzp= [HW,ACPI] 2059 Specify global default ACPI thermal zone polling rate 2060 <deci-seconds>: poll all this frequency 2061 0: no polling (default) 2062 2063 tipar.timeout= [HW,PPT] 2064 Set communications timeout in tenths of a second 2065 (default 15). 2066 2067 tipar.delay= [HW,PPT] 2068 Set inter-bit delay in microseconds (default 10). 2069 2070 tmscsim= [HW,SCSI] 2071 See comment before function dc390_setup() in 2072 drivers/scsi/tmscsim.c. 2073 2074 tp720= [HW,PS2] 2075 2076 trix= [HW,OSS] MediaTrix AudioTrix Pro 2077 Format: 2078 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq> 2079 2080 turbografx.map[2|3]= [HW,JOY] 2081 TurboGraFX parallel port interface 2082 Format: 2083 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 2084 See also Documentation/input/joystick-parport.txt 2085 2086 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter 2087 See header of drivers/scsi/u14-34f.c. 2088 2089 uart401= [HW,OSS] 2090 Format: <io>,<irq> 2091 2092 uart6850= [HW,OSS] 2093 Format: <io>,<irq> 2094 2095 uhci-hcd.ignore_oc= 2096 [USB] Ignore overcurrent events (default N). 2097 Some badly-designed motherboards generate lots of 2098 bogus events, for ports that aren't wired to 2099 anything. Set this parameter to avoid log spamming. 2100 Note that genuine overcurrent events won't be 2101 reported either. 2102 2103 usbcore.autosuspend= 2104 [USB] The autosuspend time delay (in seconds) used 2105 for newly-detected USB devices (default 2). This 2106 is the time required before an idle device will be 2107 autosuspended. Devices for which the delay is set 2108 to a negative value won't be autosuspended at all. 2109 2110 usbhid.mousepoll= 2111 [USBHID] The interval which mice are to be polled at. 2112 2113 vdso= [X86-32,SH,x86-64] 2114 vdso=2: enable compat VDSO (default with COMPAT_VDSO) 2115 vdso=1: enable VDSO (default) 2116 vdso=0: disable VDSO mapping 2117 2118 vdso32= [X86-32,X86-64] 2119 vdso32=2: enable compat VDSO (default with COMPAT_VDSO) 2120 vdso32=1: enable 32-bit VDSO (default) 2121 vdso32=0: disable 32-bit VDSO mapping 2122 2123 vector= [IA-64,SMP] 2124 vector=percpu: enable percpu vector domain 2125 2126 video= [FB] Frame buffer configuration 2127 See Documentation/fb/modedb.txt. 2128 2129 vga= [BOOT,X86-32] Select a particular video mode 2130 See Documentation/i386/boot.txt and 2131 Documentation/svga.txt. 2132 Use vga=ask for menu. 2133 This is actually a boot loader parameter; the value is 2134 passed to the kernel using a special protocol. 2135 2136 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 2137 size of <nn>. This can be used to increase the 2138 minimum size (128MB on x86). It can also be used to 2139 decrease the size and leave more room for directly 2140 mapped kernel RAM. 2141 2142 vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 2143 Format: <command> 2144 2145 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 2146 Format: <command> 2147 2148 vmpoff= [KNL,S390] Perform z/VM CP command after power off. 2149 Format: <command> 2150 2151 waveartist= [HW,OSS] 2152 Format: <io>,<irq>,<dma>,<dma2> 2153 2154 wd33c93= [HW,SCSI] 2155 See header of drivers/scsi/wd33c93.c. 2156 2157 wd7000= [HW,SCSI] 2158 See header of drivers/scsi/wd7000.c. 2159 2160 wdt= [WDT] Watchdog 2161 See Documentation/watchdog/wdt.txt. 2162 2163 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. 2164 xd_geo= See header of drivers/block/xd.c. 2165 2166 xirc2ps_cs= [NET,PCMCIA] 2167 Format: 2168 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 2169 2170 norandmaps Don't use address space randomization 2171 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space 2172 2173______________________________________________________________________ 2174 2175TODO: 2176 2177 Add documentation for ALSA options. 2178 Add more DRM drivers.