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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 clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 402 [Deprecated] 403 Forces specified clocksource (if available) to be used 404 when calculating gettimeofday(). If specified 405 clocksource is not available, it defaults to PIT. 406 Format: { pit | tsc | cyclone | pmtmr } 407 408 clocksource= [GENERIC_TIME] Override the default clocksource 409 Format: <string> 410 Override the default clocksource and use the clocksource 411 with the name specified. 412 Some clocksource names to choose from, depending on 413 the platform: 414 [all] jiffies (this is the base, fallback clocksource) 415 [ACPI] acpi_pm 416 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 417 pxa_timer,timer3,32k_counter,timer0_1 418 [AVR32] avr32 419 [X86-32] pit,hpet,tsc,vmi-timer; 420 scx200_hrt on Geode; cyclone on IBM x440 421 [MIPS] MIPS 422 [PARISC] cr16 423 [S390] tod 424 [SH] SuperH 425 [SPARC64] tick 426 [X86-64] hpet,tsc 427 428 clearcpuid=BITNUM [X86] 429 Disable CPUID feature X for the kernel. See 430 include/asm-x86/cpufeature.h for the valid bit numbers. 431 Note the Linux specific bits are not necessarily 432 stable over kernel options, but the vendor specific 433 ones should be. 434 Also note that user programs calling CPUID directly 435 or using the feature without checking anything 436 will still see it. This just prevents it from 437 being used by the kernel or shown in /proc/cpuinfo. 438 Also note the kernel might malfunction if you disable 439 some critical bits. 440 441 code_bytes [IA32/X86_64] How many bytes of object code to print 442 in an oops report. 443 Range: 0 - 8192 444 Default: 64 445 446 disable_8254_timer 447 enable_8254_timer 448 [IA32/X86_64] Disable/Enable interrupt 0 timer routing 449 over the 8254 in addition to over the IO-APIC. The 450 kernel tries to set a sensible default. 451 452 hpet= [X86-32,HPET] option to control HPET usage 453 Format: { enable (default) | disable | force } 454 disable: disable HPET and use PIT instead 455 force: allow force enabled of undocumented chips (ICH4, 456 VIA, nVidia) 457 458 com20020= [HW,NET] ARCnet - COM20020 chipset 459 Format: 460 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 461 462 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 463 Format: <io>[,<irq>] 464 465 com90xx= [HW,NET] 466 ARCnet - COM90xx chipset (memory-mapped buffers) 467 Format: <io>[,<irq>[,<memstart>]] 468 469 condev= [HW,S390] console device 470 conmode= 471 472 console= [KNL] Output console device and options. 473 474 tty<n> Use the virtual console device <n>. 475 476 ttyS<n>[,options] 477 ttyUSB0[,options] 478 Use the specified serial port. The options are of 479 the form "bbbbpnf", where "bbbb" is the baud rate, 480 "p" is parity ("n", "o", or "e"), "n" is number of 481 bits, and "f" is flow control ("r" for RTS or 482 omit it). Default is "9600n8". 483 484 See Documentation/serial-console.txt for more 485 information. See 486 Documentation/networking/netconsole.txt for an 487 alternative. 488 489 uart[8250],io,<addr>[,options] 490 uart[8250],mmio,<addr>[,options] 491 Start an early, polled-mode console on the 8250/16550 492 UART at the specified I/O port or MMIO address, 493 switching to the matching ttyS device later. The 494 options are the same as for ttyS, above. 495 496 If the device connected to the port is not a TTY but a braille 497 device, prepend "brl," before the device type, for instance 498 console=brl,ttyS0 499 For now, only VisioBraille is supported. 500 501 earlycon= [KNL] Output early console device and options. 502 uart[8250],io,<addr>[,options] 503 uart[8250],mmio,<addr>[,options] 504 Start an early, polled-mode console on the 8250/16550 505 UART at the specified I/O port or MMIO address. 506 The options are the same as for ttyS, above. 507 508 no_console_suspend 509 [HW] Never suspend the console 510 Disable suspending of consoles during suspend and 511 hibernate operations. Once disabled, debugging 512 messages can reach various consoles while the rest 513 of the system is being put to sleep (ie, while 514 debugging driver suspend/resume hooks). This may 515 not work reliably with all consoles, but is known 516 to work with serial and VGA consoles. 517 518 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 519 Format: 520 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 521 522 crashkernel=nn[KMG]@ss[KMG] 523 [KNL] Reserve a chunk of physical memory to 524 hold a kernel to switch to with kexec on panic. 525 526 crashkernel=range1:size1[,range2:size2,...][@offset] 527 [KNL] Same as above, but depends on the memory 528 in the running system. The syntax of range is 529 start-[end] where start and end are both 530 a memory unit (amount[KMG]). See also 531 Documentation/kdump/kdump.txt for a example. 532 533 cs4232= [HW,OSS] 534 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq> 535 536 cs89x0_dma= [HW,NET] 537 Format: <dma> 538 539 cs89x0_media= [HW,NET] 540 Format: { rj45 | aui | bnc } 541 542 dasd= [HW,NET] 543 See header of drivers/s390/block/dasd_devmap.c. 544 545 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 546 (one device per port) 547 Format: <port#>,<type> 548 See also Documentation/input/joystick-parport.txt 549 550 debug [KNL] Enable kernel debugging (events log level). 551 552 debug_locks_verbose= 553 [KNL] verbose self-tests 554 Format=<0|1> 555 Print debugging info while doing the locking API 556 self-tests. 557 We default to 0 (no extra messages), setting it to 558 1 will print _a lot_ more information - normally 559 only useful to kernel developers. 560 561 debug_objects [KNL] Enable object debugging 562 563 decnet.addr= [HW,NET] 564 Format: <area>[,<node>] 565 See also Documentation/networking/decnet.txt. 566 567 vt.default_blu= [VT] 568 Format: <blue0>,<blue1>,<blue2>,...,<blue15> 569 Change the default blue palette of the console. 570 This is a 16-member array composed of values 571 ranging from 0-255. 572 573 vt.default_grn= [VT] 574 Format: <green0>,<green1>,<green2>,...,<green15> 575 Change the default green palette of the console. 576 This is a 16-member array composed of values 577 ranging from 0-255. 578 579 vt.default_red= [VT] 580 Format: <red0>,<red1>,<red2>,...,<red15> 581 Change the default red palette of the console. 582 This is a 16-member array composed of values 583 ranging from 0-255. 584 585 vt.default_utf8= 586 [VT] 587 Format=<0|1> 588 Set system-wide default UTF-8 mode for all tty's. 589 Default is 1, i.e. UTF-8 mode is enabled for all 590 newly opened terminals. 591 592 dhash_entries= [KNL] 593 Set number of hash buckets for dentry cache. 594 595 digi= [HW,SERIAL] 596 IO parameters + enable/disable command. 597 598 digiepca= [HW,SERIAL] 599 See drivers/char/README.epca and 600 Documentation/digiepca.txt. 601 602 disable_mtrr_trim [X86, Intel and AMD only] 603 By default the kernel will trim any uncacheable 604 memory out of your available memory pool based on 605 MTRR settings. This parameter disables that behavior, 606 possibly causing your machine to run very slowly. 607 608 dmasound= [HW,OSS] Sound subsystem buffers 609 610 dscc4.setup= [NET] 611 612 dtc3181e= [HW,SCSI] 613 614 earlyprintk= [X86-32,X86-64,SH,BLACKFIN] 615 earlyprintk=vga 616 earlyprintk=serial[,ttySn[,baudrate]] 617 618 Append ",keep" to not disable it when the real console 619 takes over. 620 621 Only vga or serial at a time, not both. 622 623 Currently only ttyS0 and ttyS1 are supported. 624 625 Interaction with the standard serial driver is not 626 very good. 627 628 The VGA output is eventually overwritten by the real 629 console. 630 631 eata= [HW,SCSI] 632 633 edd= [EDD] 634 Format: {"off" | "on" | "skip[mbr]"} 635 636 eisa_irq_edge= [PARISC,HW] 637 See header of drivers/parisc/eisa.c. 638 639 elanfreq= [X86-32] 640 See comment before function elanfreq_setup() in 641 arch/i386/kernel/cpu/cpufreq/elanfreq.c. 642 643 elevator= [IOSCHED] 644 Format: {"anticipatory" | "cfq" | "deadline" | "noop"} 645 See Documentation/block/as-iosched.txt and 646 Documentation/block/deadline-iosched.txt for details. 647 648 elfcorehdr= [X86-32, X86_64] 649 Specifies physical address of start of kernel core 650 image elf header. Generally kexec loader will 651 pass this option to capture kernel. 652 See Documentation/kdump/kdump.txt for details. 653 654 enforcing [SELINUX] Set initial enforcing status. 655 Format: {"0" | "1"} 656 See security/selinux/Kconfig help text. 657 0 -- permissive (log only, no denials). 658 1 -- enforcing (deny and log). 659 Default value is 0. 660 Value can be changed at runtime via /selinux/enforce. 661 662 es1371= [HW,OSS] 663 Format: <spdif>,[<nomix>,[<amplifier>]] 664 See also header of sound/oss/es1371.c. 665 666 ether= [HW,NET] Ethernet cards parameters 667 This option is obsoleted by the "netdev=" option, which 668 has equivalent usage. See its documentation for details. 669 670 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. 671 Format: <io>[,<irq>] 672 673 failslab= 674 fail_page_alloc= 675 fail_make_request=[KNL] 676 General fault injection mechanism. 677 Format: <interval>,<probability>,<space>,<times> 678 See also /Documentation/fault-injection/. 679 680 fd_mcs= [HW,SCSI] 681 See header of drivers/scsi/fd_mcs.c. 682 683 fdomain= [HW,SCSI] 684 See header of drivers/scsi/fdomain.c. 685 686 floppy= [HW] 687 See Documentation/floppy.txt. 688 689 force_pal_cache_flush 690 [IA-64] Avoid check_sal_cache_flush which may hang on 691 buggy SAL_CACHE_FLUSH implementations. Using this 692 parameter will force ia64_sal_cache_flush to call 693 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. 694 695 gamecon.map[2|3]= 696 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 697 support via parallel port (up to 5 devices per port) 698 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 699 See also Documentation/input/joystick-parport.txt 700 701 gamma= [HW,DRM] 702 703 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART 704 Format: off | on 705 default: on 706 707 gdth= [HW,SCSI] 708 See header of drivers/scsi/gdth.c. 709 710 gpt [EFI] Forces disk with valid GPT signature but 711 invalid Protective MBR to be treated as GPT. 712 713 gvp11= [HW,SCSI] 714 715 hashdist= [KNL,NUMA] Large hashes allocated during boot 716 are distributed across NUMA nodes. Defaults on 717 for IA-64, off otherwise. 718 Format: 0 | 1 (for off | on) 719 720 hcl= [IA-64] SGI's Hardware Graph compatibility layer 721 722 hd= [EIDE] (E)IDE hard drive subsystem geometry 723 Format: <cyl>,<head>,<sect> 724 725 hd?= [HW] (E)IDE subsystem 726 hd?lun= See Documentation/ide/ide.txt. 727 728 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 729 size of <nn>. This works even on boxes that have no 730 highmem otherwise. This also works to reduce highmem 731 size on bigger boxes. 732 733 highres= [KNL] Enable/disable high resolution timer mode. 734 Valid parameters: "on", "off" 735 Default: "on" 736 737 hisax= [HW,ISDN] 738 See Documentation/isdn/README.HiSax. 739 740 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages. 741 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages. 742 743 i8042.direct [HW] Put keyboard port into non-translated mode 744 i8042.dumbkbd [HW] Pretend that controller can only read data from 745 keyboard and cannot control its state 746 (Don't attempt to blink the leds) 747 i8042.noaux [HW] Don't check for auxiliary (== mouse) port 748 i8042.nokbd [HW] Don't check/create keyboard port 749 i8042.noloop [HW] Disable the AUX Loopback command while probing 750 for the AUX port 751 i8042.nomux [HW] Don't check presence of an active multiplexing 752 controller 753 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 754 controllers 755 i8042.panicblink= 756 [HW] Frequency with which keyboard LEDs should blink 757 when kernel panics (default is 0.5 sec) 758 i8042.reset [HW] Reset the controller during init and cleanup 759 i8042.unlock [HW] Unlock (ignore) the keylock 760 761 i810= [HW,DRM] 762 763 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 764 indicates that the driver is running on unsupported 765 hardware. 766 i8k.force [HW] Activate i8k driver even if SMM BIOS signature 767 does not match list of supported models. 768 i8k.power_status 769 [HW] Report power status in /proc/i8k 770 (disabled by default) 771 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 772 capability is set. 773 774 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter 775 See Documentation/mca.txt. 776 777 icn= [HW,ISDN] 778 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 779 780 ide= [HW] (E)IDE subsystem 781 Format: ide=nodma or ide=doubler 782 See Documentation/ide/ide.txt. 783 784 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed 785 See Documentation/ide/ide.txt. 786 787 idle= [X86] 788 Format: idle=poll or idle=mwait 789 Poll forces a polling idle loop that can slightly improves the performance 790 of waking up a idle CPU, but will use a lot of power and make the system 791 run hot. Not recommended. 792 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose 793 to not use it because it doesn't save as much power as a normal idle 794 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same 795 as idle=poll. 796 797 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 798 Claim all unknown PCI IDE storage controllers. 799 800 ignore_loglevel [KNL] 801 Ignore loglevel setting - this will print /all/ 802 kernel messages to the console. Useful for debugging. 803 804 ihash_entries= [KNL] 805 Set number of hash buckets for inode cache. 806 807 in2000= [HW,SCSI] 808 See header of drivers/scsi/in2000.c. 809 810 init= [KNL] 811 Format: <full_path> 812 Run specified binary instead of /sbin/init as init 813 process. 814 815 initcall_debug [KNL] Trace initcalls as they are executed. Useful 816 for working out where the kernel is dying during 817 startup. 818 819 initrd= [BOOT] Specify the location of the initial ramdisk 820 821 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 822 Format: <irq> 823 824 inttest= [IA64] 825 826 iommu= [x86] 827 off 828 force 829 noforce 830 biomerge 831 panic 832 nopanic 833 merge 834 nomerge 835 forcesac 836 soft 837 838 839 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 840 off 841 Disable intel iommu driver. 842 igfx_off [Default Off] 843 By default, gfx is mapped as normal device. If a gfx 844 device has a dedicated DMAR unit, the DMAR unit is 845 bypassed by not enabling DMAR with this option. In 846 this case, gfx device will use physical address for 847 DMA. 848 forcedac [x86_64] 849 With this option iommu will not optimize to look 850 for io virtual address below 32 bit forcing dual 851 address cycle on pci bus for cards supporting greater 852 than 32 bit addressing. The default is to look 853 for translation below 32 bit and if not available 854 then look in the higher range. 855 strict [Default Off] 856 With this option on every unmap_single operation will 857 result in a hardware IOTLB flush operation as opposed 858 to batching them for performance. 859 860 io_delay= [X86-32,X86-64] I/O delay method 861 0x80 862 Standard port 0x80 based delay 863 0xed 864 Alternate port 0xed based delay (needed on some systems) 865 udelay 866 Simple two microseconds delay 867 none 868 No delay 869 870 io7= [HW] IO7 for Marvel based alpha systems 871 See comment before marvel_specify_io7 in 872 arch/alpha/kernel/core_marvel.c. 873 874 ip= [IP_PNP] 875 See Documentation/filesystems/nfsroot.txt. 876 877 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards 878 See comment before ip2_setup() in 879 drivers/char/ip2/ip2base.c. 880 881 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller 882 See header of drivers/scsi/ips.c. 883 884 ports= [IP_VS_FTP] IPVS ftp helper module 885 Default is 21. 886 Up to 8 (IP_VS_APP_MAX_PORTS) ports 887 may be specified. 888 Format: <port>,<port>.... 889 890 irqfixup [HW] 891 When an interrupt is not handled search all handlers 892 for it. Intended to get systems with badly broken 893 firmware running. 894 895 irqpoll [HW] 896 When an interrupt is not handled search all handlers 897 for it. Also check all handlers each timer 898 interrupt. Intended to get systems with badly broken 899 firmware running. 900 901 isapnp= [ISAPNP] 902 Format: <RDP>,<reset>,<pci_scan>,<verbosity> 903 904 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. 905 Format: 906 <cpu number>,...,<cpu number> 907 or 908 <cpu number>-<cpu number> (must be a positive range in ascending order) 909 or a mixture 910 <cpu number>,...,<cpu number>-<cpu number> 911 This option can be used to specify one or more CPUs 912 to isolate from the general SMP balancing and scheduling 913 algorithms. The only way to move a process onto or off 914 an "isolated" CPU is via the CPU affinity syscalls. 915 <cpu number> begins at 0 and the maximum value is 916 "number of CPUs in system - 1". 917 918 This option is the preferred way to isolate CPUs. The 919 alternative -- manually setting the CPU mask of all 920 tasks in the system -- can cause problems and 921 suboptimal load balancer performance. 922 923 iucv= [HW,NET] 924 925 js= [HW,JOY] Analog joystick 926 See Documentation/input/joystick.txt. 927 928 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 929 specifies the amount of memory usable by the kernel 930 for non-movable allocations. The requested amount is 931 spread evenly throughout all nodes in the system. The 932 remaining memory in each node is used for Movable 933 pages. In the event, a node is too small to have both 934 kernelcore and Movable pages, kernelcore pages will 935 take priority and other nodes will have a larger number 936 of kernelcore pages. The Movable zone is used for the 937 allocation of pages that may be reclaimed or moved 938 by the page migration subsystem. This means that 939 HugeTLB pages may not be allocated from this zone. 940 Note that allocations like PTEs-from-HighMem still 941 use the HighMem zone if it exists, and the Normal 942 zone if it does not. 943 944 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 945 is similar to kernelcore except it specifies the 946 amount of memory used for migratable allocations. 947 If both kernelcore and movablecore is specified, 948 then kernelcore will be at *least* the specified 949 value but may be more. If movablecore on its own 950 is specified, the administrator must be careful 951 that the amount of memory usable for all allocations 952 is not too small. 953 954 keepinitrd [HW,ARM] 955 956 kstack=N [X86-32,X86-64] Print N words from the kernel stack 957 in oops dumps. 958 959 kgdboc= [HW] kgdb over consoles. 960 Requires a tty driver that supports console polling. 961 (only serial suported for now) 962 Format: <serial_device>[,baud] 963 964 l2cr= [PPC] 965 966 l3cr= [PPC] 967 968 lapic [X86-32,APIC] Enable the local APIC even if BIOS 969 disabled it. 970 971 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in 972 C2 power state. 973 974 libata.dma= [LIBATA] DMA control 975 libata.dma=0 Disable all PATA and SATA DMA 976 libata.dma=1 PATA and SATA Disk DMA only 977 libata.dma=2 ATAPI (CDROM) DMA only 978 libata.dma=4 Compact Flash DMA only 979 Combinations also work, so libata.dma=3 enables DMA 980 for disks and CDROMs, but not CFs. 981 982 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 983 when set. 984 Format: <int> 985 986 libata.force= [LIBATA] Force configurations. The format is comma 987 separated list of "[ID:]VAL" where ID is 988 PORT[:DEVICE]. PORT and DEVICE are decimal numbers 989 matching port, link or device. Basically, it matches 990 the ATA ID string printed on console by libata. If 991 the whole ID part is omitted, the last PORT and DEVICE 992 values are used. If ID hasn't been specified yet, the 993 configuration applies to all ports, links and devices. 994 995 If only DEVICE is omitted, the parameter applies to 996 the port and all links and devices behind it. DEVICE 997 number of 0 either selects the first device or the 998 first fan-out link behind PMP device. It does not 999 select the host link. DEVICE number of 15 selects the 1000 host link and device attached to it. 1001 1002 The VAL specifies the configuration to force. As long 1003 as there's no ambiguity shortcut notation is allowed. 1004 For example, both 1.5 and 1.5G would work for 1.5Gbps. 1005 The following configurations can be forced. 1006 1007 * Cable type: 40c, 80c, short40c, unk, ign or sata. 1008 Any ID with matching PORT is used. 1009 1010 * SATA link speed limit: 1.5Gbps or 3.0Gbps. 1011 1012 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 1013 udma[/][16,25,33,44,66,100,133] notation is also 1014 allowed. 1015 1016 * [no]ncq: Turn on or off NCQ. 1017 1018 If there are multiple matching configurations changing 1019 the same attribute, the last one is used. 1020 1021 load_ramdisk= [RAM] List of ramdisks to load from floppy 1022 See Documentation/ramdisk.txt. 1023 1024 lockd.nlm_grace_period=P [NFS] Assign grace period. 1025 Format: <integer> 1026 1027 lockd.nlm_tcpport=N [NFS] Assign TCP port. 1028 Format: <integer> 1029 1030 lockd.nlm_timeout=T [NFS] Assign timeout value. 1031 Format: <integer> 1032 1033 lockd.nlm_udpport=M [NFS] Assign UDP port. 1034 Format: <integer> 1035 1036 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 1037 Format: <irq> 1038 1039 loglevel= All Kernel Messages with a loglevel smaller than the 1040 console loglevel will be printed to the console. It can 1041 also be changed with klogd or other programs. The 1042 loglevels are defined as follows: 1043 1044 0 (KERN_EMERG) system is unusable 1045 1 (KERN_ALERT) action must be taken immediately 1046 2 (KERN_CRIT) critical conditions 1047 3 (KERN_ERR) error conditions 1048 4 (KERN_WARNING) warning conditions 1049 5 (KERN_NOTICE) normal but significant condition 1050 6 (KERN_INFO) informational 1051 7 (KERN_DEBUG) debug-level messages 1052 1053 log_buf_len=n Sets the size of the printk ring buffer, in bytes. 1054 Format: { n | nk | nM } 1055 n must be a power of two. The default size 1056 is set in the kernel config file. 1057 1058 logo.nologo [FB] Disables display of the built-in Linux logo. 1059 This may be used to provide more screen space for 1060 kernel log messages and is useful when debugging 1061 kernel boot problems. 1062 1063 lp=0 [LP] Specify parallel ports to use, e.g, 1064 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 1065 lp=reset first parallel port). 'lp=0' disables the 1066 lp=auto printer driver. 'lp=reset' (which can be 1067 specified in addition to the ports) causes 1068 attached printers to be reset. Using 1069 lp=port1,port2,... specifies the parallel ports 1070 to associate lp devices with, starting with 1071 lp0. A port specification may be 'none' to skip 1072 that lp device, or a parport name such as 1073 'parport0'. Specifying 'lp=auto' instead of a 1074 port specification list means that device IDs 1075 from each port should be examined, to see if 1076 an IEEE 1284-compliant printer is attached; if 1077 so, the driver will manage that printer. 1078 See also header of drivers/char/lp.c. 1079 1080 lpj=n [KNL] 1081 Sets loops_per_jiffy to given constant, thus avoiding 1082 time-consuming boot-time autodetection (up to 250 ms per 1083 CPU). 0 enables autodetection (default). To determine 1084 the correct value for your kernel, boot with normal 1085 autodetection and see what value is printed. Note that 1086 on SMP systems the preset will be applied to all CPUs, 1087 which is likely to cause problems if your CPUs need 1088 significantly divergent settings. An incorrect value 1089 will cause delays in the kernel to be wrong, leading to 1090 unpredictable I/O errors and other breakage. Although 1091 unlikely, in the extreme case this might damage your 1092 hardware. 1093 1094 ltpc= [NET] 1095 Format: <io>,<irq>,<dma> 1096 1097 mac5380= [HW,SCSI] Format: 1098 <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 skip_isa_align [X86] do not align io start addr, so can 1529 handle more pci cards 1530 firmware [ARM] Do not re-enumerate the bus but instead 1531 just use the configuration from the 1532 bootloader. This is currently used on 1533 IXP2000 systems where the bus has to be 1534 configured a certain way for adjunct CPUs. 1535 noearly [X86] Don't do any early type 1 scanning. 1536 This might help on some broken boards which 1537 machine check when some devices' config space 1538 is read. But various workarounds are disabled 1539 and some IOMMU drivers will not work. 1540 bfsort Sort PCI devices into breadth-first order. 1541 This sorting is done to get a device 1542 order compatible with older (<= 2.4) kernels. 1543 nobfsort Don't sort PCI devices into breadth-first order. 1544 cbiosize=nn[KMG] The fixed amount of bus space which is 1545 reserved for the CardBus bridge's IO window. 1546 The default value is 256 bytes. 1547 cbmemsize=nn[KMG] The fixed amount of bus space which is 1548 reserved for the CardBus bridge's memory 1549 window. The default value is 64 megabytes. 1550 1551 pcmv= [HW,PCMCIA] BadgePAD 4 1552 1553 pd. [PARIDE] 1554 See Documentation/paride.txt. 1555 1556 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 1557 boot time. 1558 Format: { 0 | 1 } 1559 See arch/parisc/kernel/pdc_chassis.c 1560 1561 pf. [PARIDE] 1562 See Documentation/paride.txt. 1563 1564 pg. [PARIDE] 1565 See Documentation/paride.txt. 1566 1567 pirq= [SMP,APIC] Manual mp-table setup 1568 See Documentation/i386/IO-APIC.txt. 1569 1570 plip= [PPT,NET] Parallel port network link 1571 Format: { parport<nr> | timid | 0 } 1572 See also Documentation/parport.txt. 1573 1574 pnpacpi= [ACPI] 1575 { off } 1576 1577 pnpbios= [ISAPNP] 1578 { on | off | curr | res | no-curr | no-res } 1579 1580 pnp_reserve_irq= 1581 [ISAPNP] Exclude IRQs for the autoconfiguration 1582 1583 pnp_reserve_dma= 1584 [ISAPNP] Exclude DMAs for the autoconfiguration 1585 1586 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 1587 Ranges are in pairs (I/O port base and size). 1588 1589 pnp_reserve_mem= 1590 [ISAPNP] Exclude memory regions for the 1591 autoconfiguration. 1592 Ranges are in pairs (memory base and size). 1593 1594 print-fatal-signals= 1595 [KNL] debug: print fatal signals 1596 print-fatal-signals=1: print segfault info to 1597 the kernel console. 1598 default: off. 1599 1600 printk.time= Show timing data prefixed to each printk message line 1601 Format: <bool> (1/Y/y=enable, 0/N/n=disable) 1602 1603 profile= [KNL] Enable kernel profiling via /proc/profile 1604 Format: [schedule,]<number> 1605 Param: "schedule" - profile schedule points. 1606 Param: <number> - step/bucket size as a power of 2 for 1607 statistical time based profiling. 1608 Param: "sleep" - profile D-state sleeping (millisecs). 1609 Requires CONFIG_SCHEDSTATS 1610 Param: "kvm" - profile VM exits. 1611 1612 processor.max_cstate= [HW,ACPI] 1613 Limit processor to maximum C-state 1614 max_cstate=9 overrides any DMI blacklist limit. 1615 1616 processor.nocst [HW,ACPI] 1617 Ignore the _CST method to determine C-states, 1618 instead using the legacy FADT method 1619 1620 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 1621 before loading. 1622 See Documentation/ramdisk.txt. 1623 1624 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 1625 probe for; one of (bare|imps|exps|lifebook|any). 1626 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 1627 per second. 1628 psmouse.resetafter= [HW,MOUSE] 1629 Try to reset the device after so many bad packets 1630 (0 = never). 1631 psmouse.resolution= 1632 [HW,MOUSE] Set desired mouse resolution, in dpi. 1633 psmouse.smartscroll= 1634 [HW,MOUSE] Controls Logitech smartscroll autorepeat. 1635 0 = disabled, 1 = enabled (default). 1636 1637 pss= [HW,OSS] Personal Sound System (ECHO ESC614) 1638 Format: 1639 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> 1640 1641 pt. [PARIDE] 1642 See Documentation/paride.txt. 1643 1644 pty.legacy_count= 1645 [KNL] Number of legacy pty's. Overwrites compiled-in 1646 default number. 1647 1648 quiet [KNL] Disable most log messages 1649 1650 r128= [HW,DRM] 1651 1652 raid= [HW,RAID] 1653 See Documentation/md.txt. 1654 1655 ramdisk_blocksize= [RAM] 1656 See Documentation/ramdisk.txt. 1657 1658 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 1659 See Documentation/ramdisk.txt. 1660 1661 rcupdate.blimit= [KNL,BOOT] 1662 Set maximum number of finished RCU callbacks to process 1663 in one batch. 1664 1665 rcupdate.qhimark= [KNL,BOOT] 1666 Set threshold of queued 1667 RCU callbacks over which batch limiting is disabled. 1668 1669 rcupdate.qlowmark= [KNL,BOOT] 1670 Set threshold of queued RCU callbacks below which 1671 batch limiting is re-enabled. 1672 1673 rdinit= [KNL] 1674 Format: <full_path> 1675 Run specified binary instead of /init from the ramdisk, 1676 used for early userspace startup. See initrd. 1677 1678 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode 1679 Format: <reboot_mode>[,<reboot_mode2>[,...]] 1680 See arch/*/kernel/reboot.c or arch/*/kernel/process.c 1681 1682 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area 1683 1684 reservetop= [X86-32] 1685 Format: nn[KMG] 1686 Reserves a hole at the top of the kernel virtual 1687 address space. 1688 1689 reset_devices [KNL] Force drivers to reset the underlying device 1690 during initialization. 1691 1692 resume= [SWSUSP] 1693 Specify the partition device for software suspend 1694 1695 resume_offset= [SWSUSP] 1696 Specify the offset from the beginning of the partition 1697 given by "resume=" at which the swap header is located, 1698 in <PAGE_SIZE> units (needed only for swap files). 1699 See Documentation/power/swsusp-and-swap-files.txt 1700 1701 retain_initrd [RAM] Keep initrd memory after extraction 1702 1703 rhash_entries= [KNL,NET] 1704 Set number of hash buckets for route cache 1705 1706 riscom8= [HW,SERIAL] 1707 Format: <io_board1>[,<io_board2>[,...<io_boardN>]] 1708 1709 ro [KNL] Mount root device read-only on boot 1710 1711 root= [KNL] Root filesystem 1712 1713 rootdelay= [KNL] Delay (in seconds) to pause before attempting to 1714 mount the root filesystem 1715 1716 rootflags= [KNL] Set root filesystem mount option string 1717 1718 rootfstype= [KNL] Set root filesystem type 1719 1720 rootwait [KNL] Wait (indefinitely) for root device to show up. 1721 Useful for devices that are detected asynchronously 1722 (e.g. USB and MMC devices). 1723 1724 root_plug.vendor_id= 1725 [ROOTPLUG] Override the default vendor ID 1726 1727 root_plug.product_id= 1728 [ROOTPLUG] Override the default product ID 1729 1730 root_plug.debug= 1731 [ROOTPLUG] Enable debugging output 1732 1733 rw [KNL] Mount root device read-write on boot 1734 1735 S [KNL] Run init in single mode 1736 1737 sa1100ir [NET] 1738 See drivers/net/irda/sa1100_ir.c. 1739 1740 sbni= [NET] Granch SBNI12 leased line adapter 1741 1742 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver 1743 Format: <io>[,<timeout>[,<isapnp>]] 1744 1745 scsi_debug_*= [SCSI] 1746 See drivers/scsi/scsi_debug.c. 1747 1748 scsi_default_dev_flags= 1749 [SCSI] SCSI default device flags 1750 Format: <integer> 1751 1752 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model 1753 Format: <vendor>:<model>:<flags> 1754 (flags are integer value) 1755 1756 scsi_logging_level= [SCSI] a bit mask of logging levels 1757 See drivers/scsi/scsi_logging.h for bits. Also 1758 settable via sysctl at dev.scsi.logging_level 1759 (/proc/sys/dev/scsi/logging_level). 1760 There is also a nice 'scsi_logging_level' script in the 1761 S390-tools package, available for download at 1762 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html 1763 1764 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are 1765 discovered. async scans them in kernel threads, 1766 allowing boot to proceed. none ignores them, expecting 1767 user space to do the scan. 1768 1769 selinux [SELINUX] Disable or enable SELinux at boot time. 1770 Format: { "0" | "1" } 1771 See security/selinux/Kconfig help text. 1772 0 -- disable. 1773 1 -- enable. 1774 Default value is set via kernel config option. 1775 If enabled at boot time, /selinux/disable can be used 1776 later to disable prior to initial policy load. 1777 1778 selinux_compat_net = 1779 [SELINUX] Set initial selinux_compat_net flag value. 1780 Format: { "0" | "1" } 1781 0 -- use new secmark-based packet controls 1782 1 -- use legacy packet controls 1783 Default value is 0 (preferred). 1784 Value can be changed at runtime via 1785 /selinux/compat_net. 1786 1787 serialnumber [BUGS=X86-32] 1788 1789 shapers= [NET] 1790 Maximal number of shapers. 1791 1792 sim710= [SCSI,HW] 1793 See header of drivers/scsi/sim710.c. 1794 1795 simeth= [IA-64] 1796 simscsi= 1797 1798 slram= [HW,MTD] 1799 1800 slub_debug[=options[,slabs]] [MM, SLUB] 1801 Enabling slub_debug allows one to determine the 1802 culprit if slab objects become corrupted. Enabling 1803 slub_debug can create guard zones around objects and 1804 may poison objects when not in use. Also tracks the 1805 last alloc / free. For more information see 1806 Documentation/vm/slub.txt. 1807 1808 slub_max_order= [MM, SLUB] 1809 Determines the maximum allowed order for slabs. 1810 A high setting may cause OOMs due to memory 1811 fragmentation. For more information see 1812 Documentation/vm/slub.txt. 1813 1814 slub_min_objects= [MM, SLUB] 1815 The minimum number of objects per slab. SLUB will 1816 increase the slab order up to slub_max_order to 1817 generate a sufficiently large slab able to contain 1818 the number of objects indicated. The higher the number 1819 of objects the smaller the overhead of tracking slabs 1820 and the less frequently locks need to be acquired. 1821 For more information see Documentation/vm/slub.txt. 1822 1823 slub_min_order= [MM, SLUB] 1824 Determines the mininum page order for slabs. Must be 1825 lower than slub_max_order. 1826 For more information see Documentation/vm/slub.txt. 1827 1828 slub_nomerge [MM, SLUB] 1829 Disable merging of slabs with similar size. May be 1830 necessary if there is some reason to distinguish 1831 allocs to different slabs. Debug options disable 1832 merging on their own. 1833 For more information see Documentation/vm/slub.txt. 1834 1835 smart2= [HW] 1836 Format: <io1>[,<io2>[,...,<io8>]] 1837 1838 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only 1839 attempt to substitute SMP alternatives once at boot. 1840 1841 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 1842 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 1843 smsc-ircc2.ircc_sir= [HW] SIR base I/O port 1844 smsc-ircc2.ircc_fir= [HW] FIR base I/O port 1845 smsc-ircc2.ircc_irq= [HW] IRQ line 1846 smsc-ircc2.ircc_dma= [HW] DMA channel 1847 smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 1848 0: Toshiba Satellite 1800 (GP data pin select) 1849 1: Fast pin select (default) 1850 2: ATC IRMode 1851 1852 snd-ad1816a= [HW,ALSA] 1853 1854 snd-ad1848= [HW,ALSA] 1855 1856 snd-ali5451= [HW,ALSA] 1857 1858 snd-als100= [HW,ALSA] 1859 1860 snd-als4000= [HW,ALSA] 1861 1862 snd-azt2320= [HW,ALSA] 1863 1864 snd-cmi8330= [HW,ALSA] 1865 1866 snd-cmipci= [HW,ALSA] 1867 1868 snd-cs4231= [HW,ALSA] 1869 1870 snd-cs4232= [HW,ALSA] 1871 1872 snd-cs4236= [HW,ALSA] 1873 1874 snd-cs4281= [HW,ALSA] 1875 1876 snd-cs46xx= [HW,ALSA] 1877 1878 snd-dt019x= [HW,ALSA] 1879 1880 snd-dummy= [HW,ALSA] 1881 1882 snd-emu10k1= [HW,ALSA] 1883 1884 snd-ens1370= [HW,ALSA] 1885 1886 snd-ens1371= [HW,ALSA] 1887 1888 snd-es968= [HW,ALSA] 1889 1890 snd-es1688= [HW,ALSA] 1891 1892 snd-es18xx= [HW,ALSA] 1893 1894 snd-es1938= [HW,ALSA] 1895 1896 snd-es1968= [HW,ALSA] 1897 1898 snd-fm801= [HW,ALSA] 1899 1900 snd-gusclassic= [HW,ALSA] 1901 1902 snd-gusextreme= [HW,ALSA] 1903 1904 snd-gusmax= [HW,ALSA] 1905 1906 snd-hdsp= [HW,ALSA] 1907 1908 snd-ice1712= [HW,ALSA] 1909 1910 snd-intel8x0= [HW,ALSA] 1911 1912 snd-interwave= [HW,ALSA] 1913 1914 snd-interwave-stb= 1915 [HW,ALSA] 1916 1917 snd-korg1212= [HW,ALSA] 1918 1919 snd-maestro3= [HW,ALSA] 1920 1921 snd-mpu401= [HW,ALSA] 1922 1923 snd-mtpav= [HW,ALSA] 1924 1925 snd-nm256= [HW,ALSA] 1926 1927 snd-opl3sa2= [HW,ALSA] 1928 1929 snd-opti92x-ad1848= 1930 [HW,ALSA] 1931 1932 snd-opti92x-cs4231= 1933 [HW,ALSA] 1934 1935 snd-opti93x= [HW,ALSA] 1936 1937 snd-pmac= [HW,ALSA] 1938 1939 snd-rme32= [HW,ALSA] 1940 1941 snd-rme96= [HW,ALSA] 1942 1943 snd-rme9652= [HW,ALSA] 1944 1945 snd-sb8= [HW,ALSA] 1946 1947 snd-sb16= [HW,ALSA] 1948 1949 snd-sbawe= [HW,ALSA] 1950 1951 snd-serial= [HW,ALSA] 1952 1953 snd-sgalaxy= [HW,ALSA] 1954 1955 snd-sonicvibes= [HW,ALSA] 1956 1957 snd-sun-amd7930= 1958 [HW,ALSA] 1959 1960 snd-sun-cs4231= [HW,ALSA] 1961 1962 snd-trident= [HW,ALSA] 1963 1964 snd-usb-audio= [HW,ALSA,USB] 1965 1966 snd-via82xx= [HW,ALSA] 1967 1968 snd-virmidi= [HW,ALSA] 1969 1970 snd-wavefront= [HW,ALSA] 1971 1972 snd-ymfpci= [HW,ALSA] 1973 1974 sonypi.*= [HW] Sony Programmable I/O Control Device driver 1975 See Documentation/sonypi.txt 1976 1977 specialix= [HW,SERIAL] Specialix multi-serial port adapter 1978 See Documentation/specialix.txt. 1979 1980 spia_io_base= [HW,MTD] 1981 spia_fio_base= 1982 spia_pedr= 1983 spia_peddr= 1984 1985 sscape= [HW,OSS] 1986 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq> 1987 1988 st= [HW,SCSI] SCSI tape parameters (buffers, etc.) 1989 See Documentation/scsi/st.txt. 1990 1991 sti= [PARISC,HW] 1992 Format: <num> 1993 Set the STI (builtin display/keyboard on the HP-PARISC 1994 machines) console (graphic card) which should be used 1995 as the initial boot-console. 1996 See also comment in drivers/video/console/sticore.c. 1997 1998 sti_font= [HW] 1999 See comment in drivers/video/console/sticore.c. 2000 2001 stifb= [HW] 2002 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 2003 2004 sunrpc.pool_mode= 2005 [NFS] 2006 Control how the NFS server code allocates CPUs to 2007 service thread pools. Depending on how many NICs 2008 you have and where their interrupts are bound, this 2009 option will affect which CPUs will do NFS serving. 2010 Note: this parameter cannot be changed while the 2011 NFS server is running. 2012 2013 auto the server chooses an appropriate mode 2014 automatically using heuristics 2015 global a single global pool contains all CPUs 2016 percpu one pool for each CPU 2017 pernode one pool for each NUMA node (equivalent 2018 to global on non-NUMA machines) 2019 2020 swiotlb= [IA-64] Number of I/O TLB slabs 2021 2022 switches= [HW,M68k] 2023 2024 sym53c416= [HW,SCSI] 2025 See header of drivers/scsi/sym53c416.c. 2026 2027 sysrq_always_enabled 2028 [KNL] 2029 Ignore sysrq setting - this boot parameter will 2030 neutralize any effect of /proc/sys/kernel/sysrq. 2031 Useful for debugging. 2032 2033 t128= [HW,SCSI] 2034 See header of drivers/scsi/t128.c. 2035 2036 tdfx= [HW,DRM] 2037 2038 thash_entries= [KNL,NET] 2039 Set number of hash buckets for TCP connection 2040 2041 thermal.act= [HW,ACPI] 2042 -1: disable all active trip points in all thermal zones 2043 <degrees C>: override all lowest active trip points 2044 2045 thermal.crt= [HW,ACPI] 2046 -1: disable all critical trip points in all thermal zones 2047 <degrees C>: lower all critical trip points 2048 2049 thermal.nocrt= [HW,ACPI] 2050 Set to disable actions on ACPI thermal zone 2051 critical and hot trip points. 2052 2053 thermal.off= [HW,ACPI] 2054 1: disable ACPI thermal control 2055 2056 thermal.psv= [HW,ACPI] 2057 -1: disable all passive trip points 2058 <degrees C>: override all passive trip points to this value 2059 2060 thermal.tzp= [HW,ACPI] 2061 Specify global default ACPI thermal zone polling rate 2062 <deci-seconds>: poll all this frequency 2063 0: no polling (default) 2064 2065 tipar.timeout= [HW,PPT] 2066 Set communications timeout in tenths of a second 2067 (default 15). 2068 2069 tipar.delay= [HW,PPT] 2070 Set inter-bit delay in microseconds (default 10). 2071 2072 tmscsim= [HW,SCSI] 2073 See comment before function dc390_setup() in 2074 drivers/scsi/tmscsim.c. 2075 2076 tp720= [HW,PS2] 2077 2078 trix= [HW,OSS] MediaTrix AudioTrix Pro 2079 Format: 2080 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq> 2081 2082 turbografx.map[2|3]= [HW,JOY] 2083 TurboGraFX parallel port interface 2084 Format: 2085 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 2086 See also Documentation/input/joystick-parport.txt 2087 2088 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter 2089 See header of drivers/scsi/u14-34f.c. 2090 2091 uart401= [HW,OSS] 2092 Format: <io>,<irq> 2093 2094 uart6850= [HW,OSS] 2095 Format: <io>,<irq> 2096 2097 uhci-hcd.ignore_oc= 2098 [USB] Ignore overcurrent events (default N). 2099 Some badly-designed motherboards generate lots of 2100 bogus events, for ports that aren't wired to 2101 anything. Set this parameter to avoid log spamming. 2102 Note that genuine overcurrent events won't be 2103 reported either. 2104 2105 usbcore.autosuspend= 2106 [USB] The autosuspend time delay (in seconds) used 2107 for newly-detected USB devices (default 2). This 2108 is the time required before an idle device will be 2109 autosuspended. Devices for which the delay is set 2110 to a negative value won't be autosuspended at all. 2111 2112 usbhid.mousepoll= 2113 [USBHID] The interval which mice are to be polled at. 2114 2115 vdso= [X86-32,SH,x86-64] 2116 vdso=2: enable compat VDSO (default with COMPAT_VDSO) 2117 vdso=1: enable VDSO (default) 2118 vdso=0: disable VDSO mapping 2119 2120 vdso32= [X86-32,X86-64] 2121 vdso32=2: enable compat VDSO (default with COMPAT_VDSO) 2122 vdso32=1: enable 32-bit VDSO (default) 2123 vdso32=0: disable 32-bit VDSO mapping 2124 2125 vector= [IA-64,SMP] 2126 vector=percpu: enable percpu vector domain 2127 2128 video= [FB] Frame buffer configuration 2129 See Documentation/fb/modedb.txt. 2130 2131 vga= [BOOT,X86-32] Select a particular video mode 2132 See Documentation/i386/boot.txt and 2133 Documentation/svga.txt. 2134 Use vga=ask for menu. 2135 This is actually a boot loader parameter; the value is 2136 passed to the kernel using a special protocol. 2137 2138 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 2139 size of <nn>. This can be used to increase the 2140 minimum size (128MB on x86). It can also be used to 2141 decrease the size and leave more room for directly 2142 mapped kernel RAM. 2143 2144 vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 2145 Format: <command> 2146 2147 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 2148 Format: <command> 2149 2150 vmpoff= [KNL,S390] Perform z/VM CP command after power off. 2151 Format: <command> 2152 2153 waveartist= [HW,OSS] 2154 Format: <io>,<irq>,<dma>,<dma2> 2155 2156 wd33c93= [HW,SCSI] 2157 See header of drivers/scsi/wd33c93.c. 2158 2159 wd7000= [HW,SCSI] 2160 See header of drivers/scsi/wd7000.c. 2161 2162 wdt= [WDT] Watchdog 2163 See Documentation/watchdog/wdt.txt. 2164 2165 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. 2166 xd_geo= See header of drivers/block/xd.c. 2167 2168 xirc2ps_cs= [NET,PCMCIA] 2169 Format: 2170 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 2171 2172 norandmaps Don't use address space randomization 2173 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space 2174 2175______________________________________________________________________ 2176 2177TODO: 2178 2179 Add documentation for ALSA options. 2180 Add more DRM drivers.