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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 (hibernation) is enabled. 91 SUSPEND System suspend states are enabled. 92 TS Appropriate touchscreen support is enabled. 93 USB USB support is enabled. 94 USBHID USB Human Interface Device support is enabled. 95 V4L Video For Linux support is enabled. 96 VGA The VGA console has been enabled. 97 VT Virtual terminal support is enabled. 98 WDT Watchdog support is enabled. 99 XT IBM PC/XT MFM hard disk support is enabled. 100 X86-32 X86-32, aka i386 architecture is enabled. 101 X86-64 X86-64 architecture is enabled. 102 More X86-64 boot options can be found in 103 Documentation/x86_64/boot-options.txt . 104 105In addition, the following text indicates that the option: 106 107 BUGS= Relates to possible processor bugs on the said processor. 108 KNL Is a kernel start-up parameter. 109 BOOT Is a boot loader parameter. 110 111Parameters denoted with BOOT are actually interpreted by the boot 112loader, and have no meaning to the kernel directly. 113Do not modify the syntax of boot loader parameters without extreme 114need or coordination with <Documentation/i386/boot.txt>. 115 116There are also arch-specific kernel-parameters not documented here. 117See for example <Documentation/x86_64/boot-options.txt>. 118 119Note that ALL kernel parameters listed below are CASE SENSITIVE, and that 120a trailing = on the name of any parameter states that that parameter will 121be entered as an environment variable, whereas its absence indicates that 122it will appear as a kernel argument readable via /proc/cmdline by programs 123running once the system is up. 124 125The number of kernel parameters is not limited, but the length of the 126complete command line (parameters including spaces etc.) is limited to 127a fixed number of characters. This limit depends on the architecture 128and is between 256 and 4096 characters. It is defined in the file 129./include/asm/setup.h as COMMAND_LINE_SIZE. 130 131 132 acpi= [HW,ACPI,X86-64,i386] 133 Advanced Configuration and Power Interface 134 Format: { force | off | ht | strict | noirq } 135 force -- enable ACPI if default was off 136 off -- disable ACPI if default was on 137 noirq -- do not use ACPI for IRQ routing 138 ht -- run only enough ACPI to enable Hyper Threading 139 strict -- Be less tolerant of platforms that are not 140 strictly ACPI specification compliant. 141 142 See also Documentation/power/pm.txt, pci=noacpi 143 144 acpi_apic_instance= [ACPI, IOAPIC] 145 Format: <int> 146 2: use 2nd APIC table, if available 147 1,0: use 1st APIC table 148 default: 0 149 150 acpi_sleep= [HW,ACPI] Sleep options 151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering } 152 See Documentation/power/video.txt for s3_bios and s3_mode. 153 s3_beep is for debugging; it makes the PC's speaker beep 154 as soon as the kernel's real-mode entry point is called. 155 s4_nohwsig prevents ACPI hardware signature from being 156 used during resume from hibernation. 157 old_ordering causes the ACPI 1.0 ordering of the _PTS 158 control method, wrt putting devices into low power 159 states, to be enforced (the ACPI 2.0 ordering of _PTS is 160 used by default). 161 162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode 163 Format: { level | edge | high | low } 164 165 acpi_irq_balance [HW,ACPI] 166 ACPI will balance active IRQs 167 default in APIC mode 168 169 acpi_irq_nobalance [HW,ACPI] 170 ACPI will not move active IRQs (default) 171 default in PIC mode 172 173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for 174 use by PCI 175 Format: <irq>,<irq>... 176 177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA 178 Format: <irq>,<irq>... 179 180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT 181 182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 183 Format: To spoof as Windows 98: ="Microsoft Windows" 184 185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings 186 acpi_osi="string1" # add string1 -- only one string 187 acpi_osi="!string2" # remove built-in string2 188 acpi_osi= # disable all strings 189 190 acpi_serialize [HW,ACPI] force serialization of AML methods 191 192 acpi_skip_timer_override [HW,ACPI] 193 Recognize and ignore IRQ0/pin2 Interrupt Override. 194 For broken nForce2 BIOS resulting in XT-PIC timer. 195 acpi_use_timer_override [HW,ACPI} 196 Use timer override. For some broken Nvidia NF5 boards 197 that require a timer override, but don't have 198 HPET 199 200 acpi.debug_layer= [HW,ACPI] 201 Format: <int> 202 Each bit of the <int> indicates an ACPI debug layer, 203 1: enable, 0: disable. It is useful for boot time 204 debugging. After system has booted up, it can be set 205 via /sys/module/acpi/parameters/debug_layer. 206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output. 207 Available bits (add the numbers together) to enable debug output 208 for specific parts of the ACPI subsystem: 209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables 210 0x10 namespace 0x20 parser 0x40 dispatcher 211 0x80 executer 0x100 resources 0x200 acpica debugger 212 0x400 os services 0x800 acpica disassembler. 213 The number can be in decimal or prefixed with 0x in hex. 214 Warning: Many of these options can produce a lot of 215 output and make your system unusable. Be very careful. 216 217 acpi.debug_level= [HW,ACPI] 218 Format: <int> 219 Each bit of the <int> indicates an ACPI debug level, 220 1: enable, 0: disable. It is useful for boot time 221 debugging. After system has booted up, it can be set 222 via /sys/module/acpi/parameters/debug_level. 223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output. 224 Available bits (add the numbers together) to enable different 225 debug output levels of the ACPI subsystem: 226 0x01 error 0x02 warn 0x04 init 0x08 debug object 227 0x10 info 0x20 init names 0x40 parse 0x80 load 228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region 229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects 230 0x10000 resources 0x20000 user requests 0x40000 package. 231 The number can be in decimal or prefixed with 0x in hex. 232 Warning: Many of these options can produce a lot of 233 output and make your system unusable. Be very careful. 234 235 acpi_pm_good [X86-32,X86-64] 236 Override the pmtimer bug detection: force the kernel 237 to assume that this machine's pmtimer latches its value 238 and always returns good values. 239 240 agp= [AGP] 241 { off | try_unsupported } 242 off: disable AGP support 243 try_unsupported: try to drive unsupported chipsets 244 (may crash computer or cause data corruption) 245 246 enable_timer_pin_1 [i386,x86-64] 247 Enable PIN 1 of APIC timer 248 Can be useful to work around chipset bugs 249 (in particular on some ATI chipsets). 250 The kernel tries to set a reasonable default. 251 252 disable_timer_pin_1 [i386,x86-64] 253 Disable PIN 1 of APIC timer 254 Can be useful to work around chipset bugs. 255 256 ad1848= [HW,OSS] 257 Format: <io>,<irq>,<dma>,<dma2>,<type> 258 259 advansys= [HW,SCSI] 260 See header of drivers/scsi/advansys.c. 261 262 advwdt= [HW,WDT] Advantech WDT 263 Format: <iostart>,<iostop> 264 265 aedsp16= [HW,OSS] Audio Excel DSP 16 266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq> 267 See also header of sound/oss/aedsp16.c. 268 269 aha152x= [HW,SCSI] 270 See Documentation/scsi/aha152x.txt. 271 272 aha1542= [HW,SCSI] 273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]] 274 275 aic7xxx= [HW,SCSI] 276 See Documentation/scsi/aic7xxx.txt. 277 278 aic79xx= [HW,SCSI] 279 See Documentation/scsi/aic79xx.txt. 280 281 amd_iommu= [HW,X86-84] 282 Pass parameters to the AMD IOMMU driver in the system. 283 Possible values are: 284 isolate - enable device isolation (each device, as far 285 as possible, will get its own protection 286 domain) 287 amd_iommu_size= [HW,X86-64] 288 Define the size of the aperture for the AMD IOMMU 289 driver. Possible values are: 290 '32M', '64M' (default), '128M', '256M', '512M', '1G' 291 292 amijoy.map= [HW,JOY] Amiga joystick support 293 Map of devices attached to JOY0DAT and JOY1DAT 294 Format: <a>,<b> 295 See also Documentation/kernel/input/joystick.txt 296 297 analog.map= [HW,JOY] Analog joystick and gamepad support 298 Specifies type or capabilities of an analog joystick 299 connected to one of 16 gameports 300 Format: <type1>,<type2>,..<type16> 301 302 apc= [HW,SPARC] 303 Power management functions (SPARCstation-4/5 + deriv.) 304 Format: noidle 305 Disable APC CPU standby support. SPARCstation-Fox does 306 not play well with APC CPU idle - disable it if you have 307 APC and your system crashes randomly. 308 309 apic= [APIC,i386] Advanced Programmable Interrupt Controller 310 Change the output verbosity whilst booting 311 Format: { quiet (default) | verbose | debug } 312 Change the amount of debugging information output 313 when initialising the APIC and IO-APIC components. 314 315 apm= [APM] Advanced Power Management 316 See header of arch/x86/kernel/apm_32.c. 317 318 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards 319 Format: <io>,<irq>,<nodeID> 320 321 ataflop= [HW,M68k] 322 323 atarimouse= [HW,MOUSE] Atari Mouse 324 325 atascsi= [HW,SCSI] Atari SCSI 326 327 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, 328 EzKey and similar keyboards 329 330 atkbd.reset= [HW] Reset keyboard during initialization 331 332 atkbd.set= [HW] Select keyboard code set 333 Format: <int> (2 = AT (default), 3 = PS/2) 334 335 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar 336 keyboards 337 338 atkbd.softraw= [HW] Choose between synthetic and real raw mode 339 Format: <bool> (0 = real, 1 = synthetic (default)) 340 341 atkbd.softrepeat= [HW] 342 Use software keyboard repeat 343 344 autotest [IA64] 345 346 baycom_epp= [HW,AX25] 347 Format: <io>,<mode> 348 349 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem 350 Format: <io>,<mode> 351 See header of drivers/net/hamradio/baycom_par.c. 352 353 baycom_ser_fdx= [HW,AX25] 354 BayCom Serial Port AX.25 Modem (Full Duplex Mode) 355 Format: <io>,<irq>,<mode>[,<baud>] 356 See header of drivers/net/hamradio/baycom_ser_fdx.c. 357 358 baycom_ser_hdx= [HW,AX25] 359 BayCom Serial Port AX.25 Modem (Half Duplex Mode) 360 Format: <io>,<irq>,<mode> 361 See header of drivers/net/hamradio/baycom_ser_hdx.c. 362 363 boot_delay= Milliseconds to delay each printk during boot. 364 Values larger than 10 seconds (10000) are changed to 365 no delay (0). 366 Format: integer 367 368 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 369 bttv.radio= Most important insmod options are available as 370 kernel args too. 371 bttv.pll= See Documentation/video4linux/bttv/Insmod-options 372 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST 373 374 BusLogic= [HW,SCSI] 375 See drivers/scsi/BusLogic.c, comment before function 376 BusLogic_ParseDriverOptions(). 377 378 c101= [NET] Moxa C101 synchronous serial card 379 380 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. 381 Sometimes CPU hardware bugs make them report the cache 382 size incorrectly. The kernel will attempt work arounds 383 to fix known problems, but for some CPUs it is not 384 possible to determine what the correct size should be. 385 This option provides an override for these situations. 386 387 security= [SECURITY] Choose a security module to enable at boot. 388 If this boot parameter is not specified, only the first 389 security module asking for security registration will be 390 loaded. An invalid security module name will be treated 391 as if no module has been chosen. 392 393 capability.disable= 394 [SECURITY] Disable capabilities. This would normally 395 be used only if an alternative security model is to be 396 configured. Potentially dangerous and should only be 397 used if you are entirely sure of the consequences. 398 399 ccw_timeout_log [S390] 400 See Documentation/s390/CommonIO for details. 401 402 cgroup_disable= [KNL] Disable a particular controller 403 Format: {name of the controller(s) to disable} 404 {Currently supported controllers - "memory"} 405 406 checkreqprot [SELINUX] Set initial checkreqprot flag value. 407 Format: { "0" | "1" } 408 See security/selinux/Kconfig help text. 409 0 -- check protection applied by kernel (includes 410 any implied execute protection). 411 1 -- check protection requested by application. 412 Default value is set via a kernel config option. 413 Value can be changed at runtime via 414 /selinux/checkreqprot. 415 416 cio_ignore= [S390] 417 See Documentation/s390/CommonIO for details. 418 419 clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 420 [Deprecated] 421 Forces specified clocksource (if available) to be used 422 when calculating gettimeofday(). If specified 423 clocksource is not available, it defaults to PIT. 424 Format: { pit | tsc | cyclone | pmtmr } 425 426 clocksource= [GENERIC_TIME] Override the default clocksource 427 Format: <string> 428 Override the default clocksource and use the clocksource 429 with the name specified. 430 Some clocksource names to choose from, depending on 431 the platform: 432 [all] jiffies (this is the base, fallback clocksource) 433 [ACPI] acpi_pm 434 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 435 pxa_timer,timer3,32k_counter,timer0_1 436 [AVR32] avr32 437 [X86-32] pit,hpet,tsc,vmi-timer; 438 scx200_hrt on Geode; cyclone on IBM x440 439 [MIPS] MIPS 440 [PARISC] cr16 441 [S390] tod 442 [SH] SuperH 443 [SPARC64] tick 444 [X86-64] hpet,tsc 445 446 clearcpuid=BITNUM [X86] 447 Disable CPUID feature X for the kernel. See 448 include/asm-x86/cpufeature.h for the valid bit numbers. 449 Note the Linux specific bits are not necessarily 450 stable over kernel options, but the vendor specific 451 ones should be. 452 Also note that user programs calling CPUID directly 453 or using the feature without checking anything 454 will still see it. This just prevents it from 455 being used by the kernel or shown in /proc/cpuinfo. 456 Also note the kernel might malfunction if you disable 457 some critical bits. 458 459 code_bytes [IA32/X86_64] How many bytes of object code to print 460 in an oops report. 461 Range: 0 - 8192 462 Default: 64 463 464 disable_8254_timer 465 enable_8254_timer 466 [IA32/X86_64] Disable/Enable interrupt 0 timer routing 467 over the 8254 in addition to over the IO-APIC. The 468 kernel tries to set a sensible default. 469 470 hpet= [X86-32,HPET] option to control HPET usage 471 Format: { enable (default) | disable | force } 472 disable: disable HPET and use PIT instead 473 force: allow force enabled of undocumented chips (ICH4, 474 VIA, nVidia) 475 476 com20020= [HW,NET] ARCnet - COM20020 chipset 477 Format: 478 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 479 480 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 481 Format: <io>[,<irq>] 482 483 com90xx= [HW,NET] 484 ARCnet - COM90xx chipset (memory-mapped buffers) 485 Format: <io>[,<irq>[,<memstart>]] 486 487 condev= [HW,S390] console device 488 conmode= 489 490 console= [KNL] Output console device and options. 491 492 tty<n> Use the virtual console device <n>. 493 494 ttyS<n>[,options] 495 ttyUSB0[,options] 496 Use the specified serial port. The options are of 497 the form "bbbbpnf", where "bbbb" is the baud rate, 498 "p" is parity ("n", "o", or "e"), "n" is number of 499 bits, and "f" is flow control ("r" for RTS or 500 omit it). Default is "9600n8". 501 502 See Documentation/serial-console.txt for more 503 information. See 504 Documentation/networking/netconsole.txt for an 505 alternative. 506 507 uart[8250],io,<addr>[,options] 508 uart[8250],mmio,<addr>[,options] 509 Start an early, polled-mode console on the 8250/16550 510 UART at the specified I/O port or MMIO address, 511 switching to the matching ttyS device later. The 512 options are the same as for ttyS, above. 513 514 If the device connected to the port is not a TTY but a braille 515 device, prepend "brl," before the device type, for instance 516 console=brl,ttyS0 517 For now, only VisioBraille is supported. 518 519 earlycon= [KNL] Output early console device and options. 520 uart[8250],io,<addr>[,options] 521 uart[8250],mmio,<addr>[,options] 522 Start an early, polled-mode console on the 8250/16550 523 UART at the specified I/O port or MMIO address. 524 The options are the same as for ttyS, above. 525 526 no_console_suspend 527 [HW] Never suspend the console 528 Disable suspending of consoles during suspend and 529 hibernate operations. Once disabled, debugging 530 messages can reach various consoles while the rest 531 of the system is being put to sleep (ie, while 532 debugging driver suspend/resume hooks). This may 533 not work reliably with all consoles, but is known 534 to work with serial and VGA consoles. 535 536 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 537 Format: 538 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 539 540 crashkernel=nn[KMG]@ss[KMG] 541 [KNL] Reserve a chunk of physical memory to 542 hold a kernel to switch to with kexec on panic. 543 544 crashkernel=range1:size1[,range2:size2,...][@offset] 545 [KNL] Same as above, but depends on the memory 546 in the running system. The syntax of range is 547 start-[end] where start and end are both 548 a memory unit (amount[KMG]). See also 549 Documentation/kdump/kdump.txt for a example. 550 551 cs4232= [HW,OSS] 552 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq> 553 554 cs89x0_dma= [HW,NET] 555 Format: <dma> 556 557 cs89x0_media= [HW,NET] 558 Format: { rj45 | aui | bnc } 559 560 dasd= [HW,NET] 561 See header of drivers/s390/block/dasd_devmap.c. 562 563 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 564 (one device per port) 565 Format: <port#>,<type> 566 See also Documentation/input/joystick-parport.txt 567 568 debug [KNL] Enable kernel debugging (events log level). 569 570 debug_locks_verbose= 571 [KNL] verbose self-tests 572 Format=<0|1> 573 Print debugging info while doing the locking API 574 self-tests. 575 We default to 0 (no extra messages), setting it to 576 1 will print _a lot_ more information - normally 577 only useful to kernel developers. 578 579 debug_objects [KNL] Enable object debugging 580 581 debugpat [X86] Enable PAT debugging 582 583 decnet.addr= [HW,NET] 584 Format: <area>[,<node>] 585 See also Documentation/networking/decnet.txt. 586 587 vt.default_blu= [VT] 588 Format: <blue0>,<blue1>,<blue2>,...,<blue15> 589 Change the default blue palette of the console. 590 This is a 16-member array composed of values 591 ranging from 0-255. 592 593 vt.default_grn= [VT] 594 Format: <green0>,<green1>,<green2>,...,<green15> 595 Change the default green palette of the console. 596 This is a 16-member array composed of values 597 ranging from 0-255. 598 599 vt.default_red= [VT] 600 Format: <red0>,<red1>,<red2>,...,<red15> 601 Change the default red palette of the console. 602 This is a 16-member array composed of values 603 ranging from 0-255. 604 605 vt.default_utf8= 606 [VT] 607 Format=<0|1> 608 Set system-wide default UTF-8 mode for all tty's. 609 Default is 1, i.e. UTF-8 mode is enabled for all 610 newly opened terminals. 611 612 dhash_entries= [KNL] 613 Set number of hash buckets for dentry cache. 614 615 digi= [HW,SERIAL] 616 IO parameters + enable/disable command. 617 618 digiepca= [HW,SERIAL] 619 See drivers/char/README.epca and 620 Documentation/digiepca.txt. 621 622 disable_mtrr_cleanup [X86] 623 enable_mtrr_cleanup [X86] 624 The kernel tries to adjust MTRR layout from continuous 625 to discrete, to make X server driver able to add WB 626 entry later. This parameter enables/disables that. 627 628 mtrr_chunk_size=nn[KMG] [X86] 629 used for mtrr cleanup. It is largest continous chunk 630 that could hold holes aka. UC entries. 631 632 mtrr_gran_size=nn[KMG] [X86] 633 Used for mtrr cleanup. It is granularity of mtrr block. 634 Default is 1. 635 Large value could prevent small alignment from 636 using up MTRRs. 637 638 mtrr_spare_reg_nr=n [X86] 639 Format: <integer> 640 Range: 0,7 : spare reg number 641 Default : 1 642 Used for mtrr cleanup. It is spare mtrr entries number. 643 Set to 2 or more if your graphical card needs more. 644 645 disable_mtrr_trim [X86, Intel and AMD only] 646 By default the kernel will trim any uncacheable 647 memory out of your available memory pool based on 648 MTRR settings. This parameter disables that behavior, 649 possibly causing your machine to run very slowly. 650 651 dmasound= [HW,OSS] Sound subsystem buffers 652 653 dscc4.setup= [NET] 654 655 dtc3181e= [HW,SCSI] 656 657 earlyprintk= [X86-32,X86-64,SH,BLACKFIN] 658 earlyprintk=vga 659 earlyprintk=serial[,ttySn[,baudrate]] 660 661 Append ",keep" to not disable it when the real console 662 takes over. 663 664 Only vga or serial at a time, not both. 665 666 Currently only ttyS0 and ttyS1 are supported. 667 668 Interaction with the standard serial driver is not 669 very good. 670 671 The VGA output is eventually overwritten by the real 672 console. 673 674 eata= [HW,SCSI] 675 676 edd= [EDD] 677 Format: {"off" | "on" | "skip[mbr]"} 678 679 eisa_irq_edge= [PARISC,HW] 680 See header of drivers/parisc/eisa.c. 681 682 elanfreq= [X86-32] 683 See comment before function elanfreq_setup() in 684 arch/x86/kernel/cpu/cpufreq/elanfreq.c. 685 686 elevator= [IOSCHED] 687 Format: {"anticipatory" | "cfq" | "deadline" | "noop"} 688 See Documentation/block/as-iosched.txt and 689 Documentation/block/deadline-iosched.txt for details. 690 691 elfcorehdr= [X86-32, X86_64] 692 Specifies physical address of start of kernel core 693 image elf header. Generally kexec loader will 694 pass this option to capture kernel. 695 See Documentation/kdump/kdump.txt for details. 696 697 enforcing [SELINUX] Set initial enforcing status. 698 Format: {"0" | "1"} 699 See security/selinux/Kconfig help text. 700 0 -- permissive (log only, no denials). 701 1 -- enforcing (deny and log). 702 Default value is 0. 703 Value can be changed at runtime via /selinux/enforce. 704 705 es1371= [HW,OSS] 706 Format: <spdif>,[<nomix>,[<amplifier>]] 707 See also header of sound/oss/es1371.c. 708 709 ether= [HW,NET] Ethernet cards parameters 710 This option is obsoleted by the "netdev=" option, which 711 has equivalent usage. See its documentation for details. 712 713 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. 714 Format: <io>[,<irq>] 715 716 failslab= 717 fail_page_alloc= 718 fail_make_request=[KNL] 719 General fault injection mechanism. 720 Format: <interval>,<probability>,<space>,<times> 721 See also /Documentation/fault-injection/. 722 723 fd_mcs= [HW,SCSI] 724 See header of drivers/scsi/fd_mcs.c. 725 726 fdomain= [HW,SCSI] 727 See header of drivers/scsi/fdomain.c. 728 729 floppy= [HW] 730 See Documentation/floppy.txt. 731 732 force_pal_cache_flush 733 [IA-64] Avoid check_sal_cache_flush which may hang on 734 buggy SAL_CACHE_FLUSH implementations. Using this 735 parameter will force ia64_sal_cache_flush to call 736 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. 737 738 gamecon.map[2|3]= 739 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 740 support via parallel port (up to 5 devices per port) 741 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 742 See also Documentation/input/joystick-parport.txt 743 744 gamma= [HW,DRM] 745 746 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART 747 Format: off | on 748 default: on 749 750 gdth= [HW,SCSI] 751 See header of drivers/scsi/gdth.c. 752 753 gpt [EFI] Forces disk with valid GPT signature but 754 invalid Protective MBR to be treated as GPT. 755 756 gvp11= [HW,SCSI] 757 758 hashdist= [KNL,NUMA] Large hashes allocated during boot 759 are distributed across NUMA nodes. Defaults on 760 for IA-64, off otherwise. 761 Format: 0 | 1 (for off | on) 762 763 hcl= [IA-64] SGI's Hardware Graph compatibility layer 764 765 hd= [EIDE] (E)IDE hard drive subsystem geometry 766 Format: <cyl>,<head>,<sect> 767 768 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 769 size of <nn>. This works even on boxes that have no 770 highmem otherwise. This also works to reduce highmem 771 size on bigger boxes. 772 773 highres= [KNL] Enable/disable high resolution timer mode. 774 Valid parameters: "on", "off" 775 Default: "on" 776 777 hisax= [HW,ISDN] 778 See Documentation/isdn/README.HiSax. 779 780 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. 781 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. 782 On x86-64 and powerpc, this option can be specified 783 multiple times interleaved with hugepages= to reserve 784 huge pages of different sizes. Valid pages sizes on 785 x86-64 are 2M (when the CPU supports "pse") and 1G 786 (when the CPU supports the "pdpe1gb" cpuinfo flag) 787 Note that 1GB pages can only be allocated at boot time 788 using hugepages= and not freed afterwards. 789 default_hugepagesz= 790 [same as hugepagesz=] The size of the default 791 HugeTLB page size. This is the size represented by 792 the legacy /proc/ hugepages APIs, used for SHM, and 793 default size when mounting hugetlbfs filesystems. 794 Defaults to the default architecture's huge page size 795 if not specified. 796 797 i8042.direct [HW] Put keyboard port into non-translated mode 798 i8042.dumbkbd [HW] Pretend that controller can only read data from 799 keyboard and cannot control its state 800 (Don't attempt to blink the leds) 801 i8042.noaux [HW] Don't check for auxiliary (== mouse) port 802 i8042.nokbd [HW] Don't check/create keyboard port 803 i8042.noloop [HW] Disable the AUX Loopback command while probing 804 for the AUX port 805 i8042.nomux [HW] Don't check presence of an active multiplexing 806 controller 807 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 808 controllers 809 i8042.panicblink= 810 [HW] Frequency with which keyboard LEDs should blink 811 when kernel panics (default is 0.5 sec) 812 i8042.reset [HW] Reset the controller during init and cleanup 813 i8042.unlock [HW] Unlock (ignore) the keylock 814 815 i810= [HW,DRM] 816 817 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 818 indicates that the driver is running on unsupported 819 hardware. 820 i8k.force [HW] Activate i8k driver even if SMM BIOS signature 821 does not match list of supported models. 822 i8k.power_status 823 [HW] Report power status in /proc/i8k 824 (disabled by default) 825 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 826 capability is set. 827 828 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter 829 See Documentation/mca.txt. 830 831 icn= [HW,ISDN] 832 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 833 834 ide= [HW] (E)IDE subsystem 835 Format: ide=nodma or ide=doubler 836 See Documentation/ide/ide.txt. 837 838 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed 839 See Documentation/ide/ide.txt. 840 841 idle= [X86] 842 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait 843 Poll forces a polling idle loop that can slightly improves the performance 844 of waking up a idle CPU, but will use a lot of power and make the system 845 run hot. Not recommended. 846 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose 847 to not use it because it doesn't save as much power as a normal idle 848 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same 849 as idle=poll. 850 idle=halt. Halt is forced to be used for CPU idle. 851 In such case C2/C3 won't be used again. 852 idle=nomwait. Disable mwait for CPU C-states 853 854 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 855 Claim all unknown PCI IDE storage controllers. 856 857 ignore_loglevel [KNL] 858 Ignore loglevel setting - this will print /all/ 859 kernel messages to the console. Useful for debugging. 860 861 ihash_entries= [KNL] 862 Set number of hash buckets for inode cache. 863 864 in2000= [HW,SCSI] 865 See header of drivers/scsi/in2000.c. 866 867 init= [KNL] 868 Format: <full_path> 869 Run specified binary instead of /sbin/init as init 870 process. 871 872 initcall_debug [KNL] Trace initcalls as they are executed. Useful 873 for working out where the kernel is dying during 874 startup. 875 876 initrd= [BOOT] Specify the location of the initial ramdisk 877 878 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 879 Format: <irq> 880 881 inttest= [IA64] 882 883 iommu= [x86] 884 off 885 force 886 noforce 887 biomerge 888 panic 889 nopanic 890 merge 891 nomerge 892 forcesac 893 soft 894 895 896 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 897 off 898 Disable intel iommu driver. 899 igfx_off [Default Off] 900 By default, gfx is mapped as normal device. If a gfx 901 device has a dedicated DMAR unit, the DMAR unit is 902 bypassed by not enabling DMAR with this option. In 903 this case, gfx device will use physical address for 904 DMA. 905 forcedac [x86_64] 906 With this option iommu will not optimize to look 907 for io virtual address below 32 bit forcing dual 908 address cycle on pci bus for cards supporting greater 909 than 32 bit addressing. The default is to look 910 for translation below 32 bit and if not available 911 then look in the higher range. 912 strict [Default Off] 913 With this option on every unmap_single operation will 914 result in a hardware IOTLB flush operation as opposed 915 to batching them for performance. 916 917 io_delay= [X86-32,X86-64] I/O delay method 918 0x80 919 Standard port 0x80 based delay 920 0xed 921 Alternate port 0xed based delay (needed on some systems) 922 udelay 923 Simple two microseconds delay 924 none 925 No delay 926 927 io7= [HW] IO7 for Marvel based alpha systems 928 See comment before marvel_specify_io7 in 929 arch/alpha/kernel/core_marvel.c. 930 931 ip= [IP_PNP] 932 See Documentation/filesystems/nfsroot.txt. 933 934 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards 935 See comment before ip2_setup() in 936 drivers/char/ip2/ip2base.c. 937 938 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller 939 See header of drivers/scsi/ips.c. 940 941 ports= [IP_VS_FTP] IPVS ftp helper module 942 Default is 21. 943 Up to 8 (IP_VS_APP_MAX_PORTS) ports 944 may be specified. 945 Format: <port>,<port>.... 946 947 irqfixup [HW] 948 When an interrupt is not handled search all handlers 949 for it. Intended to get systems with badly broken 950 firmware running. 951 952 irqpoll [HW] 953 When an interrupt is not handled search all handlers 954 for it. Also check all handlers each timer 955 interrupt. Intended to get systems with badly broken 956 firmware running. 957 958 isapnp= [ISAPNP] 959 Format: <RDP>,<reset>,<pci_scan>,<verbosity> 960 961 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. 962 Format: 963 <cpu number>,...,<cpu number> 964 or 965 <cpu number>-<cpu number> (must be a positive range in ascending order) 966 or a mixture 967 <cpu number>,...,<cpu number>-<cpu number> 968 This option can be used to specify one or more CPUs 969 to isolate from the general SMP balancing and scheduling 970 algorithms. The only way to move a process onto or off 971 an "isolated" CPU is via the CPU affinity syscalls. 972 <cpu number> begins at 0 and the maximum value is 973 "number of CPUs in system - 1". 974 975 This option is the preferred way to isolate CPUs. The 976 alternative -- manually setting the CPU mask of all 977 tasks in the system -- can cause problems and 978 suboptimal load balancer performance. 979 980 iucv= [HW,NET] 981 982 js= [HW,JOY] Analog joystick 983 See Documentation/input/joystick.txt. 984 985 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 986 specifies the amount of memory usable by the kernel 987 for non-movable allocations. The requested amount is 988 spread evenly throughout all nodes in the system. The 989 remaining memory in each node is used for Movable 990 pages. In the event, a node is too small to have both 991 kernelcore and Movable pages, kernelcore pages will 992 take priority and other nodes will have a larger number 993 of kernelcore pages. The Movable zone is used for the 994 allocation of pages that may be reclaimed or moved 995 by the page migration subsystem. This means that 996 HugeTLB pages may not be allocated from this zone. 997 Note that allocations like PTEs-from-HighMem still 998 use the HighMem zone if it exists, and the Normal 999 zone if it does not. 1000 1001 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 1002 is similar to kernelcore except it specifies the 1003 amount of memory used for migratable allocations. 1004 If both kernelcore and movablecore is specified, 1005 then kernelcore will be at *least* the specified 1006 value but may be more. If movablecore on its own 1007 is specified, the administrator must be careful 1008 that the amount of memory usable for all allocations 1009 is not too small. 1010 1011 keepinitrd [HW,ARM] 1012 1013 kstack=N [X86-32,X86-64] Print N words from the kernel stack 1014 in oops dumps. 1015 1016 kgdboc= [HW] kgdb over consoles. 1017 Requires a tty driver that supports console polling. 1018 (only serial suported for now) 1019 Format: <serial_device>[,baud] 1020 1021 l2cr= [PPC] 1022 1023 l3cr= [PPC] 1024 1025 lapic [X86-32,APIC] Enable the local APIC even if BIOS 1026 disabled it. 1027 1028 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in 1029 C2 power state. 1030 1031 libata.dma= [LIBATA] DMA control 1032 libata.dma=0 Disable all PATA and SATA DMA 1033 libata.dma=1 PATA and SATA Disk DMA only 1034 libata.dma=2 ATAPI (CDROM) DMA only 1035 libata.dma=4 Compact Flash DMA only 1036 Combinations also work, so libata.dma=3 enables DMA 1037 for disks and CDROMs, but not CFs. 1038 1039 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 1040 when set. 1041 Format: <int> 1042 1043 libata.force= [LIBATA] Force configurations. The format is comma 1044 separated list of "[ID:]VAL" where ID is 1045 PORT[:DEVICE]. PORT and DEVICE are decimal numbers 1046 matching port, link or device. Basically, it matches 1047 the ATA ID string printed on console by libata. If 1048 the whole ID part is omitted, the last PORT and DEVICE 1049 values are used. If ID hasn't been specified yet, the 1050 configuration applies to all ports, links and devices. 1051 1052 If only DEVICE is omitted, the parameter applies to 1053 the port and all links and devices behind it. DEVICE 1054 number of 0 either selects the first device or the 1055 first fan-out link behind PMP device. It does not 1056 select the host link. DEVICE number of 15 selects the 1057 host link and device attached to it. 1058 1059 The VAL specifies the configuration to force. As long 1060 as there's no ambiguity shortcut notation is allowed. 1061 For example, both 1.5 and 1.5G would work for 1.5Gbps. 1062 The following configurations can be forced. 1063 1064 * Cable type: 40c, 80c, short40c, unk, ign or sata. 1065 Any ID with matching PORT is used. 1066 1067 * SATA link speed limit: 1.5Gbps or 3.0Gbps. 1068 1069 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 1070 udma[/][16,25,33,44,66,100,133] notation is also 1071 allowed. 1072 1073 * [no]ncq: Turn on or off NCQ. 1074 1075 If there are multiple matching configurations changing 1076 the same attribute, the last one is used. 1077 1078 load_ramdisk= [RAM] List of ramdisks to load from floppy 1079 See Documentation/ramdisk.txt. 1080 1081 lockd.nlm_grace_period=P [NFS] Assign grace period. 1082 Format: <integer> 1083 1084 lockd.nlm_tcpport=N [NFS] Assign TCP port. 1085 Format: <integer> 1086 1087 lockd.nlm_timeout=T [NFS] Assign timeout value. 1088 Format: <integer> 1089 1090 lockd.nlm_udpport=M [NFS] Assign UDP port. 1091 Format: <integer> 1092 1093 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 1094 Format: <irq> 1095 1096 loglevel= All Kernel Messages with a loglevel smaller than the 1097 console loglevel will be printed to the console. It can 1098 also be changed with klogd or other programs. The 1099 loglevels are defined as follows: 1100 1101 0 (KERN_EMERG) system is unusable 1102 1 (KERN_ALERT) action must be taken immediately 1103 2 (KERN_CRIT) critical conditions 1104 3 (KERN_ERR) error conditions 1105 4 (KERN_WARNING) warning conditions 1106 5 (KERN_NOTICE) normal but significant condition 1107 6 (KERN_INFO) informational 1108 7 (KERN_DEBUG) debug-level messages 1109 1110 log_buf_len=n Sets the size of the printk ring buffer, in bytes. 1111 Format: { n | nk | nM } 1112 n must be a power of two. The default size 1113 is set in the kernel config file. 1114 1115 logo.nologo [FB] Disables display of the built-in Linux logo. 1116 This may be used to provide more screen space for 1117 kernel log messages and is useful when debugging 1118 kernel boot problems. 1119 1120 lp=0 [LP] Specify parallel ports to use, e.g, 1121 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 1122 lp=reset first parallel port). 'lp=0' disables the 1123 lp=auto printer driver. 'lp=reset' (which can be 1124 specified in addition to the ports) causes 1125 attached printers to be reset. Using 1126 lp=port1,port2,... specifies the parallel ports 1127 to associate lp devices with, starting with 1128 lp0. A port specification may be 'none' to skip 1129 that lp device, or a parport name such as 1130 'parport0'. Specifying 'lp=auto' instead of a 1131 port specification list means that device IDs 1132 from each port should be examined, to see if 1133 an IEEE 1284-compliant printer is attached; if 1134 so, the driver will manage that printer. 1135 See also header of drivers/char/lp.c. 1136 1137 lpj=n [KNL] 1138 Sets loops_per_jiffy to given constant, thus avoiding 1139 time-consuming boot-time autodetection (up to 250 ms per 1140 CPU). 0 enables autodetection (default). To determine 1141 the correct value for your kernel, boot with normal 1142 autodetection and see what value is printed. Note that 1143 on SMP systems the preset will be applied to all CPUs, 1144 which is likely to cause problems if your CPUs need 1145 significantly divergent settings. An incorrect value 1146 will cause delays in the kernel to be wrong, leading to 1147 unpredictable I/O errors and other breakage. Although 1148 unlikely, in the extreme case this might damage your 1149 hardware. 1150 1151 ltpc= [NET] 1152 Format: <io>,<irq>,<dma> 1153 1154 mac5380= [HW,SCSI] Format: 1155 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> 1156 1157 machvec= [IA64] Force the use of a particular machine-vector 1158 (machvec) in a generic kernel. 1159 Example: machvec=hpzx1_swiotlb 1160 1161 max_loop= [LOOP] Maximum number of loopback devices that can 1162 be mounted 1163 Format: <1-256> 1164 1165 maxcpus= [SMP] Maximum number of processors that an SMP kernel 1166 should make use of. maxcpus=n : n >= 0 limits the 1167 kernel to using 'n' processors. n=0 is a special case, 1168 it is equivalent to "nosmp", which also disables 1169 the IO APIC. 1170 1171 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or 1172 equal to this physical address is ignored. 1173 1174 max_luns= [SCSI] Maximum number of LUNs to probe. 1175 Should be between 1 and 2^32-1. 1176 1177 max_report_luns= 1178 [SCSI] Maximum number of LUNs received. 1179 Should be between 1 and 16384. 1180 1181 mcatest= [IA-64] 1182 1183 mce [X86-32] Machine Check Exception 1184 1185 mce=option [X86-64] See Documentation/x86_64/boot-options.txt 1186 1187 md= [HW] RAID subsystems devices and level 1188 See Documentation/md.txt. 1189 1190 mdacon= [MDA] 1191 Format: <first>,<last> 1192 Specifies range of consoles to be captured by the MDA. 1193 1194 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 1195 Amount of memory to be used when the kernel is not able 1196 to see the whole system memory or for test. 1197 [X86-32] Use together with memmap= to avoid physical 1198 address space collisions. Without memmap= PCI devices 1199 could be placed at addresses belonging to unused RAM. 1200 1201 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 1202 memory. 1203 1204 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact 1205 E820 memory map, as specified by the user. 1206 Such memmap=exactmap lines can be constructed based on 1207 BIOS output or other requirements. See the memmap=nn@ss 1208 option description. 1209 1210 memmap=nn[KMG]@ss[KMG] 1211 [KNL] Force usage of a specific region of memory 1212 Region of memory to be used, from ss to ss+nn. 1213 1214 memmap=nn[KMG]#ss[KMG] 1215 [KNL,ACPI] Mark specific memory as ACPI data. 1216 Region of memory to be used, from ss to ss+nn. 1217 1218 memmap=nn[KMG]$ss[KMG] 1219 [KNL,ACPI] Mark specific memory as reserved. 1220 Region of memory to be used, from ss to ss+nn. 1221 Example: Exclude memory from 0x18690000-0x1869ffff 1222 memmap=64K$0x18690000 1223 or 1224 memmap=0x10000$0x18690000 1225 1226 memtest= [KNL,X86] Enable memtest 1227 Format: <integer> 1228 range: 0,4 : pattern number 1229 default : 0 <disable> 1230 1231 meye.*= [HW] Set MotionEye Camera parameters 1232 See Documentation/video4linux/meye.txt. 1233 1234 mfgpt_irq= [IA-32] Specify the IRQ to use for the 1235 Multi-Function General Purpose Timers on AMD Geode 1236 platforms. 1237 1238 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when 1239 the BIOS has incorrectly applied a workaround. TinyBIOS 1240 version 0.98 is known to be affected, 0.99 fixes the 1241 problem by letting the user disable the workaround. 1242 1243 mga= [HW,DRM] 1244 1245 mminit_loglevel= 1246 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this 1247 parameter allows control of the logging verbosity for 1248 the additional memory initialisation checks. A value 1249 of 0 disables mminit logging and a level of 4 will 1250 log everything. Information is printed at KERN_DEBUG 1251 so loglevel=8 may also need to be specified. 1252 1253 mousedev.tap_time= 1254 [MOUSE] Maximum time between finger touching and 1255 leaving touchpad surface for touch to be considered 1256 a tap and be reported as a left button click (for 1257 touchpads working in absolute mode only). 1258 Format: <msecs> 1259 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 1260 reporting absolute coordinates, such as tablets 1261 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 1262 reporting absolute coordinates, such as tablets 1263 1264 mpu401= [HW,OSS] 1265 Format: <io>,<irq> 1266 1267 MTD_Partition= [MTD] 1268 Format: <name>,<region-number>,<size>,<offset> 1269 1270 MTD_Region= [MTD] Format: 1271 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 1272 1273 mtdparts= [MTD] 1274 See drivers/mtd/cmdlinepart.c. 1275 1276 mtdset= [ARM] 1277 ARM/S3C2412 JIVE boot control 1278 1279 See arch/arm/mach-s3c2412/mach-jive.c 1280 1281 mtouchusb.raw_coordinates= 1282 [HW] Make the MicroTouch USB driver use raw coordinates 1283 ('y', default) or cooked coordinates ('n') 1284 1285 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 1286 1287 NCR_D700= [HW,SCSI] 1288 See header of drivers/scsi/NCR_D700.c. 1289 1290 ncr5380= [HW,SCSI] 1291 1292 ncr53c400= [HW,SCSI] 1293 1294 ncr53c400a= [HW,SCSI] 1295 1296 ncr53c406a= [HW,SCSI] 1297 1298 ncr53c8xx= [HW,SCSI] 1299 1300 netdev= [NET] Network devices parameters 1301 Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 1302 Note that mem_start is often overloaded to mean 1303 something different and driver-specific. 1304 This usage is only documented in each driver source 1305 file if at all. 1306 1307 nf_conntrack.acct= 1308 [NETFILTER] Enable connection tracking flow accounting 1309 0 to disable accounting 1310 1 to enable accounting 1311 Default value depends on CONFIG_NF_CT_ACCT that is 1312 going to be removed in 2.6.29. 1313 1314 nfsaddrs= [NFS] 1315 See Documentation/filesystems/nfsroot.txt. 1316 1317 nfsroot= [NFS] nfs root filesystem for disk-less boxes. 1318 See Documentation/filesystems/nfsroot.txt. 1319 1320 nfs.callback_tcpport= 1321 [NFS] set the TCP port on which the NFSv4 callback 1322 channel should listen. 1323 1324 nfs.idmap_cache_timeout= 1325 [NFS] set the maximum lifetime for idmapper cache 1326 entries. 1327 1328 nfs.enable_ino64= 1329 [NFS] enable 64-bit inode numbers. 1330 If zero, the NFS client will fake up a 32-bit inode 1331 number for the readdir() and stat() syscalls instead 1332 of returning the full 64-bit number. 1333 The default is to return 64-bit inode numbers. 1334 1335 nmi_debug= [KNL,AVR32] Specify one or more actions to take 1336 when a NMI is triggered. 1337 Format: [state][,regs][,debounce][,die] 1338 1339 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels 1340 1341 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths 1342 emulation library even if a 387 maths coprocessor 1343 is present. 1344 1345 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien 1346 caches in the slab allocator. Saves per-node memory, 1347 but will impact performance. 1348 1349 noalign [KNL,ARM] 1350 1351 noapic [SMP,APIC] Tells the kernel to not make use of any 1352 IOAPICs that may be present in the system. 1353 1354 nobats [PPC] Do not use BATs for mapping kernel lowmem 1355 on "Classic" PPC cores. 1356 1357 nocache [ARM] 1358 1359 nodelayacct [KNL] Disable per-task delay accounting 1360 1361 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. 1362 1363 noefi [X86-32,X86-64] Disable EFI runtime services support. 1364 1365 noexec [IA-64] 1366 1367 noexec [X86-32,X86-64] 1368 On X86-32 available only on PAE configured kernels. 1369 noexec=on: enable non-executable mappings (default) 1370 noexec=off: disable non-executable mappings 1371 1372 noexec32 [X86-64] 1373 This affects only 32-bit executables. 1374 noexec32=on: enable non-executable mappings (default) 1375 read doesn't imply executable mappings 1376 noexec32=off: disable non-executable mappings 1377 read implies executable mappings 1378 1379 nofxsr [BUGS=X86-32] Disables x86 floating point extended 1380 register save and restore. The kernel will only save 1381 legacy floating-point registers on task switch. 1382 1383 noclflush [BUGS=X86] Don't use the CLFLUSH instruction 1384 1385 nohlt [BUGS=ARM] 1386 1387 no-hlt [BUGS=X86-32] Tells the kernel that the hlt 1388 instruction doesn't work correctly and not to 1389 use it. 1390 1391 nohalt [IA-64] Tells the kernel not to use the power saving 1392 function PAL_HALT_LIGHT when idle. This increases 1393 power-consumption. On the positive side, it reduces 1394 interrupt wake-up latency, which may improve performance 1395 in certain environments such as networked servers or 1396 real-time systems. 1397 1398 nohz= [KNL] Boottime enable/disable dynamic ticks 1399 Valid arguments: on, off 1400 Default: on 1401 1402 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing 1403 1404 noirqdebug [X86-32] Disables the code which attempts to detect and 1405 disable unhandled interrupt sources. 1406 1407 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for 1408 broken timer IRQ sources. 1409 1410 noisapnp [ISAPNP] Disables ISA PnP code. 1411 1412 noinitrd [RAM] Tells the kernel not to load any configured 1413 initial RAM disk. 1414 1415 nointroute [IA-64] 1416 1417 nojitter [IA64] Disables jitter checking for ITC timers. 1418 1419 nolapic [X86-32,APIC] Do not enable or use the local APIC. 1420 1421 nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 1422 1423 noltlbs [PPC] Do not use large page/tlb entries for kernel 1424 lowmem mapping on PPC40x. 1425 1426 nomca [IA-64] Disable machine check abort handling 1427 1428 nomce [X86-32] Machine Check Exception 1429 1430 nomfgpt [X86-32] Disable Multi-Function General Purpose 1431 Timer usage (for AMD Geode machines). 1432 1433 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops 1434 1435 noreplace-smp [X86-32,SMP] Don't replace SMP instructions 1436 with UP alternatives 1437 1438 noresidual [PPC] Don't use residual data on PReP machines. 1439 1440 noresume [SWSUSP] Disables resume and restores original swap 1441 space. 1442 1443 no-scroll [VGA] Disables scrollback. 1444 This is required for the Braillex ib80-piezo Braille 1445 reader made by F.H. Papenmeier (Germany). 1446 1447 nosbagart [IA-64] 1448 1449 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. 1450 1451 nosmp [SMP] Tells an SMP kernel to act as a UP kernel, 1452 and disable the IO APIC. legacy for "maxcpus=0". 1453 1454 nosoftlockup [KNL] Disable the soft-lockup detector. 1455 1456 nosync [HW,M68K] Disables sync negotiation for all devices. 1457 1458 notsc [BUGS=X86-32] Disable Time Stamp Counter 1459 1460 nousb [USB] Disable the USB subsystem 1461 1462 nowb [ARM] 1463 1464 nptcg= [IA64] Override max number of concurrent global TLB 1465 purges which is reported from either PAL_VM_SUMMARY or 1466 SAL PALO. 1467 1468 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 1469 one of ['zone', 'node', 'default'] can be specified 1470 This can be set from sysctl after boot. 1471 See Documentation/sysctl/vm.txt for details. 1472 1473 nr_uarts= [SERIAL] maximum number of UARTs to be registered. 1474 1475 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands 1476 Rather than timing out after 20 ms if an EC 1477 command is not properly ACKed, override the length 1478 of the timeout. We have interrupts disabled while 1479 waiting for the ACK, so if this is set too high 1480 interrupts *may* be lost! 1481 1482 opl3= [HW,OSS] 1483 Format: <io> 1484 1485 oprofile.timer= [HW] 1486 Use timer interrupt instead of performance counters 1487 1488 osst= [HW,SCSI] SCSI Tape Driver 1489 Format: <buffer_size>,<write_threshold> 1490 See also Documentation/scsi/st.txt. 1491 1492 panic= [KNL] Kernel behaviour on panic 1493 Format: <timeout> 1494 1495 parkbd.port= [HW] Parallel port number the keyboard adapter is 1496 connected to, default is 0. 1497 Format: <parport#> 1498 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 1499 0 for XT, 1 for AT (default is AT). 1500 Format: <mode> 1501 1502 parport= [HW,PPT] Specify parallel ports. 0 disables. 1503 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 1504 Use 'auto' to force the driver to use any 1505 IRQ/DMA settings detected (the default is to 1506 ignore detected IRQ/DMA settings because of 1507 possible conflicts). You can specify the base 1508 address, IRQ, and DMA settings; IRQ and DMA 1509 should be numbers, or 'auto' (for using detected 1510 settings on that particular port), or 'nofifo' 1511 (to avoid using a FIFO even if it is detected). 1512 Parallel ports are assigned in the order they 1513 are specified on the command line, starting 1514 with parport0. 1515 1516 parport_init_mode= [HW,PPT] 1517 Configure VIA parallel port to operate in 1518 a specific mode. This is necessary on Pegasos 1519 computer where firmware has no options for setting 1520 up parallel port mode and sets it to spp. 1521 Currently this function knows 686a and 8231 chips. 1522 Format: [spp|ps2|epp|ecp|ecpepp] 1523 1524 pas2= [HW,OSS] Format: 1525 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16> 1526 1527 pas16= [HW,SCSI] 1528 See header of drivers/scsi/pas16.c. 1529 1530 pause_on_oops= 1531 Halt all CPUs after the first oops has been printed for 1532 the specified number of seconds. This is to be used if 1533 your oopses keep scrolling off the screen. 1534 1535 pcbit= [HW,ISDN] 1536 1537 pcd. [PARIDE] 1538 See header of drivers/block/paride/pcd.c. 1539 See also Documentation/paride.txt. 1540 1541 pci=option[,option...] [PCI] various PCI subsystem options: 1542 off [X86-32] don't probe for the PCI bus 1543 bios [X86-32] force use of PCI BIOS, don't access 1544 the hardware directly. Use this if your machine 1545 has a non-standard PCI host bridge. 1546 nobios [X86-32] disallow use of PCI BIOS, only direct 1547 hardware access methods are allowed. Use this 1548 if you experience crashes upon bootup and you 1549 suspect they are caused by the BIOS. 1550 conf1 [X86-32] Force use of PCI Configuration 1551 Mechanism 1. 1552 conf2 [X86-32] Force use of PCI Configuration 1553 Mechanism 2. 1554 noaer [PCIE] If the PCIEAER kernel config parameter is 1555 enabled, this kernel boot option can be used to 1556 disable the use of PCIE advanced error reporting. 1557 nodomains [PCI] Disable support for multiple PCI 1558 root domains (aka PCI segments, in ACPI-speak). 1559 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI 1560 Configuration 1561 nomsi [MSI] If the PCI_MSI kernel config parameter is 1562 enabled, this kernel boot option can be used to 1563 disable the use of MSI interrupts system-wide. 1564 biosirq [X86-32] Use PCI BIOS calls to get the interrupt 1565 routing table. These calls are known to be buggy 1566 on several machines and they hang the machine 1567 when used, but on other computers it's the only 1568 way to get the interrupt routing table. Try 1569 this option if the kernel is unable to allocate 1570 IRQs or discover secondary PCI buses on your 1571 motherboard. 1572 rom [X86-32] Assign address space to expansion ROMs. 1573 Use with caution as certain devices share 1574 address decoders between ROMs and other 1575 resources. 1576 norom [X86-32,X86_64] Do not assign address space to 1577 expansion ROMs that do not already have 1578 BIOS assigned address ranges. 1579 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be 1580 assigned automatically to PCI devices. You can 1581 make the kernel exclude IRQs of your ISA cards 1582 this way. 1583 pirqaddr=0xAAAAA [X86-32] Specify the physical address 1584 of the PIRQ table (normally generated 1585 by the BIOS) if it is outside the 1586 F0000h-100000h range. 1587 lastbus=N [X86-32] Scan all buses thru bus #N. Can be 1588 useful if the kernel is unable to find your 1589 secondary buses and you want to tell it 1590 explicitly which ones they are. 1591 assign-busses [X86-32] Always assign all PCI bus 1592 numbers ourselves, overriding 1593 whatever the firmware may have done. 1594 usepirqmask [X86-32] Honor the possible IRQ mask stored 1595 in the BIOS $PIR table. This is needed on 1596 some systems with broken BIOSes, notably 1597 some HP Pavilion N5400 and Omnibook XE3 1598 notebooks. This will have no effect if ACPI 1599 IRQ routing is enabled. 1600 noacpi [X86-32] Do not use ACPI for IRQ routing 1601 or for PCI scanning. 1602 use_crs [X86-32] Use _CRS for PCI resource 1603 allocation. 1604 routeirq Do IRQ routing for all PCI devices. 1605 This is normally done in pci_enable_device(), 1606 so this option is a temporary workaround 1607 for broken drivers that don't call it. 1608 skip_isa_align [X86] do not align io start addr, so can 1609 handle more pci cards 1610 firmware [ARM] Do not re-enumerate the bus but instead 1611 just use the configuration from the 1612 bootloader. This is currently used on 1613 IXP2000 systems where the bus has to be 1614 configured a certain way for adjunct CPUs. 1615 noearly [X86] Don't do any early type 1 scanning. 1616 This might help on some broken boards which 1617 machine check when some devices' config space 1618 is read. But various workarounds are disabled 1619 and some IOMMU drivers will not work. 1620 bfsort Sort PCI devices into breadth-first order. 1621 This sorting is done to get a device 1622 order compatible with older (<= 2.4) kernels. 1623 nobfsort Don't sort PCI devices into breadth-first order. 1624 cbiosize=nn[KMG] The fixed amount of bus space which is 1625 reserved for the CardBus bridge's IO window. 1626 The default value is 256 bytes. 1627 cbmemsize=nn[KMG] The fixed amount of bus space which is 1628 reserved for the CardBus bridge's memory 1629 window. The default value is 64 megabytes. 1630 1631 pcmv= [HW,PCMCIA] BadgePAD 4 1632 1633 pd. [PARIDE] 1634 See Documentation/paride.txt. 1635 1636 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 1637 boot time. 1638 Format: { 0 | 1 } 1639 See arch/parisc/kernel/pdc_chassis.c 1640 1641 pf. [PARIDE] 1642 See Documentation/paride.txt. 1643 1644 pg. [PARIDE] 1645 See Documentation/paride.txt. 1646 1647 pirq= [SMP,APIC] Manual mp-table setup 1648 See Documentation/i386/IO-APIC.txt. 1649 1650 plip= [PPT,NET] Parallel port network link 1651 Format: { parport<nr> | timid | 0 } 1652 See also Documentation/parport.txt. 1653 1654 pmtmr= [X86] Manual setup of pmtmr I/O Port. 1655 Override pmtimer IOPort with a hex value. 1656 e.g. pmtmr=0x508 1657 1658 pnpacpi= [ACPI] 1659 { off } 1660 1661 pnpbios= [ISAPNP] 1662 { on | off | curr | res | no-curr | no-res } 1663 1664 pnp_reserve_irq= 1665 [ISAPNP] Exclude IRQs for the autoconfiguration 1666 1667 pnp_reserve_dma= 1668 [ISAPNP] Exclude DMAs for the autoconfiguration 1669 1670 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 1671 Ranges are in pairs (I/O port base and size). 1672 1673 pnp_reserve_mem= 1674 [ISAPNP] Exclude memory regions for the 1675 autoconfiguration. 1676 Ranges are in pairs (memory base and size). 1677 1678 print-fatal-signals= 1679 [KNL] debug: print fatal signals 1680 print-fatal-signals=1: print segfault info to 1681 the kernel console. 1682 default: off. 1683 1684 printk.time= Show timing data prefixed to each printk message line 1685 Format: <bool> (1/Y/y=enable, 0/N/n=disable) 1686 1687 profile= [KNL] Enable kernel profiling via /proc/profile 1688 Format: [schedule,]<number> 1689 Param: "schedule" - profile schedule points. 1690 Param: <number> - step/bucket size as a power of 2 for 1691 statistical time based profiling. 1692 Param: "sleep" - profile D-state sleeping (millisecs). 1693 Requires CONFIG_SCHEDSTATS 1694 Param: "kvm" - profile VM exits. 1695 1696 processor.max_cstate= [HW,ACPI] 1697 Limit processor to maximum C-state 1698 max_cstate=9 overrides any DMI blacklist limit. 1699 1700 processor.nocst [HW,ACPI] 1701 Ignore the _CST method to determine C-states, 1702 instead using the legacy FADT method 1703 1704 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 1705 before loading. 1706 See Documentation/ramdisk.txt. 1707 1708 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 1709 probe for; one of (bare|imps|exps|lifebook|any). 1710 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 1711 per second. 1712 psmouse.resetafter= [HW,MOUSE] 1713 Try to reset the device after so many bad packets 1714 (0 = never). 1715 psmouse.resolution= 1716 [HW,MOUSE] Set desired mouse resolution, in dpi. 1717 psmouse.smartscroll= 1718 [HW,MOUSE] Controls Logitech smartscroll autorepeat. 1719 0 = disabled, 1 = enabled (default). 1720 1721 pss= [HW,OSS] Personal Sound System (ECHO ESC614) 1722 Format: 1723 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> 1724 1725 pt. [PARIDE] 1726 See Documentation/paride.txt. 1727 1728 pty.legacy_count= 1729 [KNL] Number of legacy pty's. Overwrites compiled-in 1730 default number. 1731 1732 quiet [KNL] Disable most log messages 1733 1734 r128= [HW,DRM] 1735 1736 raid= [HW,RAID] 1737 See Documentation/md.txt. 1738 1739 ramdisk_blocksize= [RAM] 1740 See Documentation/ramdisk.txt. 1741 1742 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 1743 See Documentation/ramdisk.txt. 1744 1745 rcupdate.blimit= [KNL,BOOT] 1746 Set maximum number of finished RCU callbacks to process 1747 in one batch. 1748 1749 rcupdate.qhimark= [KNL,BOOT] 1750 Set threshold of queued 1751 RCU callbacks over which batch limiting is disabled. 1752 1753 rcupdate.qlowmark= [KNL,BOOT] 1754 Set threshold of queued RCU callbacks below which 1755 batch limiting is re-enabled. 1756 1757 rdinit= [KNL] 1758 Format: <full_path> 1759 Run specified binary instead of /init from the ramdisk, 1760 used for early userspace startup. See initrd. 1761 1762 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode 1763 Format: <reboot_mode>[,<reboot_mode2>[,...]] 1764 See arch/*/kernel/reboot.c or arch/*/kernel/process.c 1765 1766 relax_domain_level= 1767 [KNL, SMP] Set scheduler's default relax_domain_level. 1768 See Documentation/cpusets.txt. 1769 1770 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area 1771 1772 reservetop= [X86-32] 1773 Format: nn[KMG] 1774 Reserves a hole at the top of the kernel virtual 1775 address space. 1776 1777 reset_devices [KNL] Force drivers to reset the underlying device 1778 during initialization. 1779 1780 resume= [SWSUSP] 1781 Specify the partition device for software suspend 1782 1783 resume_offset= [SWSUSP] 1784 Specify the offset from the beginning of the partition 1785 given by "resume=" at which the swap header is located, 1786 in <PAGE_SIZE> units (needed only for swap files). 1787 See Documentation/power/swsusp-and-swap-files.txt 1788 1789 retain_initrd [RAM] Keep initrd memory after extraction 1790 1791 rhash_entries= [KNL,NET] 1792 Set number of hash buckets for route cache 1793 1794 riscom8= [HW,SERIAL] 1795 Format: <io_board1>[,<io_board2>[,...<io_boardN>]] 1796 1797 ro [KNL] Mount root device read-only on boot 1798 1799 root= [KNL] Root filesystem 1800 1801 rootdelay= [KNL] Delay (in seconds) to pause before attempting to 1802 mount the root filesystem 1803 1804 rootflags= [KNL] Set root filesystem mount option string 1805 1806 rootfstype= [KNL] Set root filesystem type 1807 1808 rootwait [KNL] Wait (indefinitely) for root device to show up. 1809 Useful for devices that are detected asynchronously 1810 (e.g. USB and MMC devices). 1811 1812 root_plug.vendor_id= 1813 [ROOTPLUG] Override the default vendor ID 1814 1815 root_plug.product_id= 1816 [ROOTPLUG] Override the default product ID 1817 1818 root_plug.debug= 1819 [ROOTPLUG] Enable debugging output 1820 1821 rw [KNL] Mount root device read-write on boot 1822 1823 S [KNL] Run init in single mode 1824 1825 sa1100ir [NET] 1826 See drivers/net/irda/sa1100_ir.c. 1827 1828 sbni= [NET] Granch SBNI12 leased line adapter 1829 1830 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver 1831 Format: <io>[,<timeout>[,<isapnp>]] 1832 1833 scsi_debug_*= [SCSI] 1834 See drivers/scsi/scsi_debug.c. 1835 1836 scsi_default_dev_flags= 1837 [SCSI] SCSI default device flags 1838 Format: <integer> 1839 1840 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model 1841 Format: <vendor>:<model>:<flags> 1842 (flags are integer value) 1843 1844 scsi_logging_level= [SCSI] a bit mask of logging levels 1845 See drivers/scsi/scsi_logging.h for bits. Also 1846 settable via sysctl at dev.scsi.logging_level 1847 (/proc/sys/dev/scsi/logging_level). 1848 There is also a nice 'scsi_logging_level' script in the 1849 S390-tools package, available for download at 1850 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html 1851 1852 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are 1853 discovered. async scans them in kernel threads, 1854 allowing boot to proceed. none ignores them, expecting 1855 user space to do the scan. 1856 1857 selinux [SELINUX] Disable or enable SELinux at boot time. 1858 Format: { "0" | "1" } 1859 See security/selinux/Kconfig help text. 1860 0 -- disable. 1861 1 -- enable. 1862 Default value is set via kernel config option. 1863 If enabled at boot time, /selinux/disable can be used 1864 later to disable prior to initial policy load. 1865 1866 selinux_compat_net = 1867 [SELINUX] Set initial selinux_compat_net flag value. 1868 Format: { "0" | "1" } 1869 0 -- use new secmark-based packet controls 1870 1 -- use legacy packet controls 1871 Default value is 0 (preferred). 1872 Value can be changed at runtime via 1873 /selinux/compat_net. 1874 1875 serialnumber [BUGS=X86-32] 1876 1877 shapers= [NET] 1878 Maximal number of shapers. 1879 1880 sim710= [SCSI,HW] 1881 See header of drivers/scsi/sim710.c. 1882 1883 simeth= [IA-64] 1884 simscsi= 1885 1886 slram= [HW,MTD] 1887 1888 slub_debug[=options[,slabs]] [MM, SLUB] 1889 Enabling slub_debug allows one to determine the 1890 culprit if slab objects become corrupted. Enabling 1891 slub_debug can create guard zones around objects and 1892 may poison objects when not in use. Also tracks the 1893 last alloc / free. For more information see 1894 Documentation/vm/slub.txt. 1895 1896 slub_max_order= [MM, SLUB] 1897 Determines the maximum allowed order for slabs. 1898 A high setting may cause OOMs due to memory 1899 fragmentation. For more information see 1900 Documentation/vm/slub.txt. 1901 1902 slub_min_objects= [MM, SLUB] 1903 The minimum number of objects per slab. SLUB will 1904 increase the slab order up to slub_max_order to 1905 generate a sufficiently large slab able to contain 1906 the number of objects indicated. The higher the number 1907 of objects the smaller the overhead of tracking slabs 1908 and the less frequently locks need to be acquired. 1909 For more information see Documentation/vm/slub.txt. 1910 1911 slub_min_order= [MM, SLUB] 1912 Determines the mininum page order for slabs. Must be 1913 lower than slub_max_order. 1914 For more information see Documentation/vm/slub.txt. 1915 1916 slub_nomerge [MM, SLUB] 1917 Disable merging of slabs with similar size. May be 1918 necessary if there is some reason to distinguish 1919 allocs to different slabs. Debug options disable 1920 merging on their own. 1921 For more information see Documentation/vm/slub.txt. 1922 1923 smart2= [HW] 1924 Format: <io1>[,<io2>[,...,<io8>]] 1925 1926 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only 1927 attempt to substitute SMP alternatives once at boot. 1928 1929 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 1930 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 1931 smsc-ircc2.ircc_sir= [HW] SIR base I/O port 1932 smsc-ircc2.ircc_fir= [HW] FIR base I/O port 1933 smsc-ircc2.ircc_irq= [HW] IRQ line 1934 smsc-ircc2.ircc_dma= [HW] DMA channel 1935 smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 1936 0: Toshiba Satellite 1800 (GP data pin select) 1937 1: Fast pin select (default) 1938 2: ATC IRMode 1939 1940 snd-ad1816a= [HW,ALSA] 1941 1942 snd-ad1848= [HW,ALSA] 1943 1944 snd-ali5451= [HW,ALSA] 1945 1946 snd-als100= [HW,ALSA] 1947 1948 snd-als4000= [HW,ALSA] 1949 1950 snd-azt2320= [HW,ALSA] 1951 1952 snd-cmi8330= [HW,ALSA] 1953 1954 snd-cmipci= [HW,ALSA] 1955 1956 snd-cs4231= [HW,ALSA] 1957 1958 snd-cs4232= [HW,ALSA] 1959 1960 snd-cs4236= [HW,ALSA] 1961 1962 snd-cs4281= [HW,ALSA] 1963 1964 snd-cs46xx= [HW,ALSA] 1965 1966 snd-dt019x= [HW,ALSA] 1967 1968 snd-dummy= [HW,ALSA] 1969 1970 snd-emu10k1= [HW,ALSA] 1971 1972 snd-ens1370= [HW,ALSA] 1973 1974 snd-ens1371= [HW,ALSA] 1975 1976 snd-es968= [HW,ALSA] 1977 1978 snd-es1688= [HW,ALSA] 1979 1980 snd-es18xx= [HW,ALSA] 1981 1982 snd-es1938= [HW,ALSA] 1983 1984 snd-es1968= [HW,ALSA] 1985 1986 snd-fm801= [HW,ALSA] 1987 1988 snd-gusclassic= [HW,ALSA] 1989 1990 snd-gusextreme= [HW,ALSA] 1991 1992 snd-gusmax= [HW,ALSA] 1993 1994 snd-hdsp= [HW,ALSA] 1995 1996 snd-ice1712= [HW,ALSA] 1997 1998 snd-intel8x0= [HW,ALSA] 1999 2000 snd-interwave= [HW,ALSA] 2001 2002 snd-interwave-stb= 2003 [HW,ALSA] 2004 2005 snd-korg1212= [HW,ALSA] 2006 2007 snd-maestro3= [HW,ALSA] 2008 2009 snd-mpu401= [HW,ALSA] 2010 2011 snd-mtpav= [HW,ALSA] 2012 2013 snd-nm256= [HW,ALSA] 2014 2015 snd-opl3sa2= [HW,ALSA] 2016 2017 snd-opti92x-ad1848= 2018 [HW,ALSA] 2019 2020 snd-opti92x-cs4231= 2021 [HW,ALSA] 2022 2023 snd-opti93x= [HW,ALSA] 2024 2025 snd-pmac= [HW,ALSA] 2026 2027 snd-rme32= [HW,ALSA] 2028 2029 snd-rme96= [HW,ALSA] 2030 2031 snd-rme9652= [HW,ALSA] 2032 2033 snd-sb8= [HW,ALSA] 2034 2035 snd-sb16= [HW,ALSA] 2036 2037 snd-sbawe= [HW,ALSA] 2038 2039 snd-serial= [HW,ALSA] 2040 2041 snd-sgalaxy= [HW,ALSA] 2042 2043 snd-sonicvibes= [HW,ALSA] 2044 2045 snd-sun-amd7930= 2046 [HW,ALSA] 2047 2048 snd-sun-cs4231= [HW,ALSA] 2049 2050 snd-trident= [HW,ALSA] 2051 2052 snd-usb-audio= [HW,ALSA,USB] 2053 2054 snd-via82xx= [HW,ALSA] 2055 2056 snd-virmidi= [HW,ALSA] 2057 2058 snd-wavefront= [HW,ALSA] 2059 2060 snd-ymfpci= [HW,ALSA] 2061 2062 softlockup_panic= 2063 [KNL] Should the soft-lockup detector generate panics. 2064 2065 sonypi.*= [HW] Sony Programmable I/O Control Device driver 2066 See Documentation/sonypi.txt 2067 2068 specialix= [HW,SERIAL] Specialix multi-serial port adapter 2069 See Documentation/specialix.txt. 2070 2071 spia_io_base= [HW,MTD] 2072 spia_fio_base= 2073 spia_pedr= 2074 spia_peddr= 2075 2076 sscape= [HW,OSS] 2077 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq> 2078 2079 st= [HW,SCSI] SCSI tape parameters (buffers, etc.) 2080 See Documentation/scsi/st.txt. 2081 2082 sti= [PARISC,HW] 2083 Format: <num> 2084 Set the STI (builtin display/keyboard on the HP-PARISC 2085 machines) console (graphic card) which should be used 2086 as the initial boot-console. 2087 See also comment in drivers/video/console/sticore.c. 2088 2089 sti_font= [HW] 2090 See comment in drivers/video/console/sticore.c. 2091 2092 stifb= [HW] 2093 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 2094 2095 sunrpc.pool_mode= 2096 [NFS] 2097 Control how the NFS server code allocates CPUs to 2098 service thread pools. Depending on how many NICs 2099 you have and where their interrupts are bound, this 2100 option will affect which CPUs will do NFS serving. 2101 Note: this parameter cannot be changed while the 2102 NFS server is running. 2103 2104 auto the server chooses an appropriate mode 2105 automatically using heuristics 2106 global a single global pool contains all CPUs 2107 percpu one pool for each CPU 2108 pernode one pool for each NUMA node (equivalent 2109 to global on non-NUMA machines) 2110 2111 swiotlb= [IA-64] Number of I/O TLB slabs 2112 2113 switches= [HW,M68k] 2114 2115 sym53c416= [HW,SCSI] 2116 See header of drivers/scsi/sym53c416.c. 2117 2118 sysrq_always_enabled 2119 [KNL] 2120 Ignore sysrq setting - this boot parameter will 2121 neutralize any effect of /proc/sys/kernel/sysrq. 2122 Useful for debugging. 2123 2124 t128= [HW,SCSI] 2125 See header of drivers/scsi/t128.c. 2126 2127 tdfx= [HW,DRM] 2128 2129 test_suspend= [SUSPEND] 2130 Specify "mem" (for Suspend-to-RAM) or "standby" (for 2131 standby suspend) as the system sleep state to briefly 2132 enter during system startup. The system is woken from 2133 this state using a wakeup-capable RTC alarm. 2134 2135 thash_entries= [KNL,NET] 2136 Set number of hash buckets for TCP connection 2137 2138 thermal.act= [HW,ACPI] 2139 -1: disable all active trip points in all thermal zones 2140 <degrees C>: override all lowest active trip points 2141 2142 thermal.crt= [HW,ACPI] 2143 -1: disable all critical trip points in all thermal zones 2144 <degrees C>: lower all critical trip points 2145 2146 thermal.nocrt= [HW,ACPI] 2147 Set to disable actions on ACPI thermal zone 2148 critical and hot trip points. 2149 2150 thermal.off= [HW,ACPI] 2151 1: disable ACPI thermal control 2152 2153 thermal.psv= [HW,ACPI] 2154 -1: disable all passive trip points 2155 <degrees C>: override all passive trip points to this value 2156 2157 thermal.tzp= [HW,ACPI] 2158 Specify global default ACPI thermal zone polling rate 2159 <deci-seconds>: poll all this frequency 2160 0: no polling (default) 2161 2162 tmscsim= [HW,SCSI] 2163 See comment before function dc390_setup() in 2164 drivers/scsi/tmscsim.c. 2165 2166 tp720= [HW,PS2] 2167 2168 trix= [HW,OSS] MediaTrix AudioTrix Pro 2169 Format: 2170 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq> 2171 2172 turbografx.map[2|3]= [HW,JOY] 2173 TurboGraFX parallel port interface 2174 Format: 2175 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 2176 See also Documentation/input/joystick-parport.txt 2177 2178 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter 2179 See header of drivers/scsi/u14-34f.c. 2180 2181 uart401= [HW,OSS] 2182 Format: <io>,<irq> 2183 2184 uart6850= [HW,OSS] 2185 Format: <io>,<irq> 2186 2187 uhci-hcd.ignore_oc= 2188 [USB] Ignore overcurrent events (default N). 2189 Some badly-designed motherboards generate lots of 2190 bogus events, for ports that aren't wired to 2191 anything. Set this parameter to avoid log spamming. 2192 Note that genuine overcurrent events won't be 2193 reported either. 2194 2195 unknown_nmi_panic 2196 [X86-32,X86-64] 2197 Set unknown_nmi_panic=1 early on boot. 2198 2199 usbcore.autosuspend= 2200 [USB] The autosuspend time delay (in seconds) used 2201 for newly-detected USB devices (default 2). This 2202 is the time required before an idle device will be 2203 autosuspended. Devices for which the delay is set 2204 to a negative value won't be autosuspended at all. 2205 2206 usbhid.mousepoll= 2207 [USBHID] The interval which mice are to be polled at. 2208 2209 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in 2210 kernel's map of available physical RAM. 2211 2212 vdso= [X86-32,SH,x86-64] 2213 vdso=2: enable compat VDSO (default with COMPAT_VDSO) 2214 vdso=1: enable VDSO (default) 2215 vdso=0: disable VDSO mapping 2216 2217 vdso32= [X86-32,X86-64] 2218 vdso32=2: enable compat VDSO (default with COMPAT_VDSO) 2219 vdso32=1: enable 32-bit VDSO (default) 2220 vdso32=0: disable 32-bit VDSO mapping 2221 2222 vector= [IA-64,SMP] 2223 vector=percpu: enable percpu vector domain 2224 2225 video= [FB] Frame buffer configuration 2226 See Documentation/fb/modedb.txt. 2227 2228 vga= [BOOT,X86-32] Select a particular video mode 2229 See Documentation/i386/boot.txt and 2230 Documentation/svga.txt. 2231 Use vga=ask for menu. 2232 This is actually a boot loader parameter; the value is 2233 passed to the kernel using a special protocol. 2234 2235 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 2236 size of <nn>. This can be used to increase the 2237 minimum size (128MB on x86). It can also be used to 2238 decrease the size and leave more room for directly 2239 mapped kernel RAM. 2240 2241 vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 2242 Format: <command> 2243 2244 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 2245 Format: <command> 2246 2247 vmpoff= [KNL,S390] Perform z/VM CP command after power off. 2248 Format: <command> 2249 2250 waveartist= [HW,OSS] 2251 Format: <io>,<irq>,<dma>,<dma2> 2252 2253 wd33c93= [HW,SCSI] 2254 See header of drivers/scsi/wd33c93.c. 2255 2256 wd7000= [HW,SCSI] 2257 See header of drivers/scsi/wd7000.c. 2258 2259 wdt= [WDT] Watchdog 2260 See Documentation/watchdog/wdt.txt. 2261 2262 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. 2263 xd_geo= See header of drivers/block/xd.c. 2264 2265 xirc2ps_cs= [NET,PCMCIA] 2266 Format: 2267 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 2268 2269 norandmaps Don't use address space randomization 2270 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space 2271 2272______________________________________________________________________ 2273 2274TODO: 2275 2276 Add documentation for ALSA options. 2277 Add more DRM drivers.