Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
1
fork

Configure Feed

Select the types of activity you want to include in your feed.

at 717d438d1fde94decef874b9808379d1f4523453 2282 lines 74 kB view raw
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 bootmem_debug [KNL] Enable bootmem allocator debug messages. 369 370 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 371 bttv.radio= Most important insmod options are available as 372 kernel args too. 373 bttv.pll= See Documentation/video4linux/bttv/Insmod-options 374 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST 375 376 BusLogic= [HW,SCSI] 377 See drivers/scsi/BusLogic.c, comment before function 378 BusLogic_ParseDriverOptions(). 379 380 c101= [NET] Moxa C101 synchronous serial card 381 382 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. 383 Sometimes CPU hardware bugs make them report the cache 384 size incorrectly. The kernel will attempt work arounds 385 to fix known problems, but for some CPUs it is not 386 possible to determine what the correct size should be. 387 This option provides an override for these situations. 388 389 security= [SECURITY] Choose a security module to enable at boot. 390 If this boot parameter is not specified, only the first 391 security module asking for security registration will be 392 loaded. An invalid security module name will be treated 393 as if no module has been chosen. 394 395 capability.disable= 396 [SECURITY] Disable capabilities. This would normally 397 be used only if an alternative security model is to be 398 configured. Potentially dangerous and should only be 399 used if you are entirely sure of the consequences. 400 401 ccw_timeout_log [S390] 402 See Documentation/s390/CommonIO for details. 403 404 cgroup_disable= [KNL] Disable a particular controller 405 Format: {name of the controller(s) to disable} 406 {Currently supported controllers - "memory"} 407 408 checkreqprot [SELINUX] Set initial checkreqprot flag value. 409 Format: { "0" | "1" } 410 See security/selinux/Kconfig help text. 411 0 -- check protection applied by kernel (includes 412 any implied execute protection). 413 1 -- check protection requested by application. 414 Default value is set via a kernel config option. 415 Value can be changed at runtime via 416 /selinux/checkreqprot. 417 418 cio_ignore= [S390] 419 See Documentation/s390/CommonIO for details. 420 421 clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 422 [Deprecated] 423 Forces specified clocksource (if available) to be used 424 when calculating gettimeofday(). If specified 425 clocksource is not available, it defaults to PIT. 426 Format: { pit | tsc | cyclone | pmtmr } 427 428 clocksource= [GENERIC_TIME] Override the default clocksource 429 Format: <string> 430 Override the default clocksource and use the clocksource 431 with the name specified. 432 Some clocksource names to choose from, depending on 433 the platform: 434 [all] jiffies (this is the base, fallback clocksource) 435 [ACPI] acpi_pm 436 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 437 pxa_timer,timer3,32k_counter,timer0_1 438 [AVR32] avr32 439 [X86-32] pit,hpet,tsc,vmi-timer; 440 scx200_hrt on Geode; cyclone on IBM x440 441 [MIPS] MIPS 442 [PARISC] cr16 443 [S390] tod 444 [SH] SuperH 445 [SPARC64] tick 446 [X86-64] hpet,tsc 447 448 clearcpuid=BITNUM [X86] 449 Disable CPUID feature X for the kernel. See 450 include/asm-x86/cpufeature.h for the valid bit numbers. 451 Note the Linux specific bits are not necessarily 452 stable over kernel options, but the vendor specific 453 ones should be. 454 Also note that user programs calling CPUID directly 455 or using the feature without checking anything 456 will still see it. This just prevents it from 457 being used by the kernel or shown in /proc/cpuinfo. 458 Also note the kernel might malfunction if you disable 459 some critical bits. 460 461 code_bytes [IA32/X86_64] How many bytes of object code to print 462 in an oops report. 463 Range: 0 - 8192 464 Default: 64 465 466 disable_8254_timer 467 enable_8254_timer 468 [IA32/X86_64] Disable/Enable interrupt 0 timer routing 469 over the 8254 in addition to over the IO-APIC. The 470 kernel tries to set a sensible default. 471 472 hpet= [X86-32,HPET] option to control HPET usage 473 Format: { enable (default) | disable | force } 474 disable: disable HPET and use PIT instead 475 force: allow force enabled of undocumented chips (ICH4, 476 VIA, nVidia) 477 478 com20020= [HW,NET] ARCnet - COM20020 chipset 479 Format: 480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 481 482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 483 Format: <io>[,<irq>] 484 485 com90xx= [HW,NET] 486 ARCnet - COM90xx chipset (memory-mapped buffers) 487 Format: <io>[,<irq>[,<memstart>]] 488 489 condev= [HW,S390] console device 490 conmode= 491 492 console= [KNL] Output console device and options. 493 494 tty<n> Use the virtual console device <n>. 495 496 ttyS<n>[,options] 497 ttyUSB0[,options] 498 Use the specified serial port. The options are of 499 the form "bbbbpnf", where "bbbb" is the baud rate, 500 "p" is parity ("n", "o", or "e"), "n" is number of 501 bits, and "f" is flow control ("r" for RTS or 502 omit it). Default is "9600n8". 503 504 See Documentation/serial-console.txt for more 505 information. See 506 Documentation/networking/netconsole.txt for an 507 alternative. 508 509 uart[8250],io,<addr>[,options] 510 uart[8250],mmio,<addr>[,options] 511 Start an early, polled-mode console on the 8250/16550 512 UART at the specified I/O port or MMIO address, 513 switching to the matching ttyS device later. The 514 options are the same as for ttyS, above. 515 516 If the device connected to the port is not a TTY but a braille 517 device, prepend "brl," before the device type, for instance 518 console=brl,ttyS0 519 For now, only VisioBraille is supported. 520 521 earlycon= [KNL] Output early console device and options. 522 uart[8250],io,<addr>[,options] 523 uart[8250],mmio,<addr>[,options] 524 Start an early, polled-mode console on the 8250/16550 525 UART at the specified I/O port or MMIO address. 526 The options are the same as for ttyS, above. 527 528 no_console_suspend 529 [HW] Never suspend the console 530 Disable suspending of consoles during suspend and 531 hibernate operations. Once disabled, debugging 532 messages can reach various consoles while the rest 533 of the system is being put to sleep (ie, while 534 debugging driver suspend/resume hooks). This may 535 not work reliably with all consoles, but is known 536 to work with serial and VGA consoles. 537 538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 539 Format: 540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 541 542 crashkernel=nn[KMG]@ss[KMG] 543 [KNL] Reserve a chunk of physical memory to 544 hold a kernel to switch to with kexec on panic. 545 546 crashkernel=range1:size1[,range2:size2,...][@offset] 547 [KNL] Same as above, but depends on the memory 548 in the running system. The syntax of range is 549 start-[end] where start and end are both 550 a memory unit (amount[KMG]). See also 551 Documentation/kdump/kdump.txt for a example. 552 553 cs4232= [HW,OSS] 554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq> 555 556 cs89x0_dma= [HW,NET] 557 Format: <dma> 558 559 cs89x0_media= [HW,NET] 560 Format: { rj45 | aui | bnc } 561 562 dasd= [HW,NET] 563 See header of drivers/s390/block/dasd_devmap.c. 564 565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 566 (one device per port) 567 Format: <port#>,<type> 568 See also Documentation/input/joystick-parport.txt 569 570 debug [KNL] Enable kernel debugging (events log level). 571 572 debug_locks_verbose= 573 [KNL] verbose self-tests 574 Format=<0|1> 575 Print debugging info while doing the locking API 576 self-tests. 577 We default to 0 (no extra messages), setting it to 578 1 will print _a lot_ more information - normally 579 only useful to kernel developers. 580 581 debug_objects [KNL] Enable object debugging 582 583 debugpat [X86] Enable PAT debugging 584 585 decnet.addr= [HW,NET] 586 Format: <area>[,<node>] 587 See also Documentation/networking/decnet.txt. 588 589 vt.default_blu= [VT] 590 Format: <blue0>,<blue1>,<blue2>,...,<blue15> 591 Change the default blue palette of the console. 592 This is a 16-member array composed of values 593 ranging from 0-255. 594 595 vt.default_grn= [VT] 596 Format: <green0>,<green1>,<green2>,...,<green15> 597 Change the default green palette of the console. 598 This is a 16-member array composed of values 599 ranging from 0-255. 600 601 vt.default_red= [VT] 602 Format: <red0>,<red1>,<red2>,...,<red15> 603 Change the default red palette of the console. 604 This is a 16-member array composed of values 605 ranging from 0-255. 606 607 vt.default_utf8= 608 [VT] 609 Format=<0|1> 610 Set system-wide default UTF-8 mode for all tty's. 611 Default is 1, i.e. UTF-8 mode is enabled for all 612 newly opened terminals. 613 614 dhash_entries= [KNL] 615 Set number of hash buckets for dentry cache. 616 617 digi= [HW,SERIAL] 618 IO parameters + enable/disable command. 619 620 digiepca= [HW,SERIAL] 621 See drivers/char/README.epca and 622 Documentation/digiepca.txt. 623 624 disable_mtrr_cleanup [X86] 625 enable_mtrr_cleanup [X86] 626 The kernel tries to adjust MTRR layout from continuous 627 to discrete, to make X server driver able to add WB 628 entry later. This parameter enables/disables that. 629 630 mtrr_chunk_size=nn[KMG] [X86] 631 used for mtrr cleanup. It is largest continous chunk 632 that could hold holes aka. UC entries. 633 634 mtrr_gran_size=nn[KMG] [X86] 635 Used for mtrr cleanup. It is granularity of mtrr block. 636 Default is 1. 637 Large value could prevent small alignment from 638 using up MTRRs. 639 640 mtrr_spare_reg_nr=n [X86] 641 Format: <integer> 642 Range: 0,7 : spare reg number 643 Default : 1 644 Used for mtrr cleanup. It is spare mtrr entries number. 645 Set to 2 or more if your graphical card needs more. 646 647 disable_mtrr_trim [X86, Intel and AMD only] 648 By default the kernel will trim any uncacheable 649 memory out of your available memory pool based on 650 MTRR settings. This parameter disables that behavior, 651 possibly causing your machine to run very slowly. 652 653 dmasound= [HW,OSS] Sound subsystem buffers 654 655 dscc4.setup= [NET] 656 657 dtc3181e= [HW,SCSI] 658 659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN] 660 earlyprintk=vga 661 earlyprintk=serial[,ttySn[,baudrate]] 662 663 Append ",keep" to not disable it when the real console 664 takes over. 665 666 Only vga or serial at a time, not both. 667 668 Currently only ttyS0 and ttyS1 are supported. 669 670 Interaction with the standard serial driver is not 671 very good. 672 673 The VGA output is eventually overwritten by the real 674 console. 675 676 eata= [HW,SCSI] 677 678 edd= [EDD] 679 Format: {"off" | "on" | "skip[mbr]"} 680 681 eisa_irq_edge= [PARISC,HW] 682 See header of drivers/parisc/eisa.c. 683 684 elanfreq= [X86-32] 685 See comment before function elanfreq_setup() in 686 arch/x86/kernel/cpu/cpufreq/elanfreq.c. 687 688 elevator= [IOSCHED] 689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"} 690 See Documentation/block/as-iosched.txt and 691 Documentation/block/deadline-iosched.txt for details. 692 693 elfcorehdr= [X86-32, X86_64] 694 Specifies physical address of start of kernel core 695 image elf header. Generally kexec loader will 696 pass this option to capture kernel. 697 See Documentation/kdump/kdump.txt for details. 698 699 enforcing [SELINUX] Set initial enforcing status. 700 Format: {"0" | "1"} 701 See security/selinux/Kconfig help text. 702 0 -- permissive (log only, no denials). 703 1 -- enforcing (deny and log). 704 Default value is 0. 705 Value can be changed at runtime via /selinux/enforce. 706 707 es1371= [HW,OSS] 708 Format: <spdif>,[<nomix>,[<amplifier>]] 709 See also header of sound/oss/es1371.c. 710 711 ether= [HW,NET] Ethernet cards parameters 712 This option is obsoleted by the "netdev=" option, which 713 has equivalent usage. See its documentation for details. 714 715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. 716 Format: <io>[,<irq>] 717 718 failslab= 719 fail_page_alloc= 720 fail_make_request=[KNL] 721 General fault injection mechanism. 722 Format: <interval>,<probability>,<space>,<times> 723 See also /Documentation/fault-injection/. 724 725 fd_mcs= [HW,SCSI] 726 See header of drivers/scsi/fd_mcs.c. 727 728 fdomain= [HW,SCSI] 729 See header of drivers/scsi/fdomain.c. 730 731 floppy= [HW] 732 See Documentation/floppy.txt. 733 734 force_pal_cache_flush 735 [IA-64] Avoid check_sal_cache_flush which may hang on 736 buggy SAL_CACHE_FLUSH implementations. Using this 737 parameter will force ia64_sal_cache_flush to call 738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. 739 740 gamecon.map[2|3]= 741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 742 support via parallel port (up to 5 devices per port) 743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 744 See also Documentation/input/joystick-parport.txt 745 746 gamma= [HW,DRM] 747 748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART 749 Format: off | on 750 default: on 751 752 gdth= [HW,SCSI] 753 See header of drivers/scsi/gdth.c. 754 755 gpt [EFI] Forces disk with valid GPT signature but 756 invalid Protective MBR to be treated as GPT. 757 758 gvp11= [HW,SCSI] 759 760 hashdist= [KNL,NUMA] Large hashes allocated during boot 761 are distributed across NUMA nodes. Defaults on 762 for IA-64, off otherwise. 763 Format: 0 | 1 (for off | on) 764 765 hcl= [IA-64] SGI's Hardware Graph compatibility layer 766 767 hd= [EIDE] (E)IDE hard drive subsystem geometry 768 Format: <cyl>,<head>,<sect> 769 770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 771 size of <nn>. This works even on boxes that have no 772 highmem otherwise. This also works to reduce highmem 773 size on bigger boxes. 774 775 highres= [KNL] Enable/disable high resolution timer mode. 776 Valid parameters: "on", "off" 777 Default: "on" 778 779 hisax= [HW,ISDN] 780 See Documentation/isdn/README.HiSax. 781 782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. 783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. 784 On x86-64 and powerpc, this option can be specified 785 multiple times interleaved with hugepages= to reserve 786 huge pages of different sizes. Valid pages sizes on 787 x86-64 are 2M (when the CPU supports "pse") and 1G 788 (when the CPU supports the "pdpe1gb" cpuinfo flag) 789 Note that 1GB pages can only be allocated at boot time 790 using hugepages= and not freed afterwards. 791 default_hugepagesz= 792 [same as hugepagesz=] The size of the default 793 HugeTLB page size. This is the size represented by 794 the legacy /proc/ hugepages APIs, used for SHM, and 795 default size when mounting hugetlbfs filesystems. 796 Defaults to the default architecture's huge page size 797 if not specified. 798 799 i8042.direct [HW] Put keyboard port into non-translated mode 800 i8042.dumbkbd [HW] Pretend that controller can only read data from 801 keyboard and cannot control its state 802 (Don't attempt to blink the leds) 803 i8042.noaux [HW] Don't check for auxiliary (== mouse) port 804 i8042.nokbd [HW] Don't check/create keyboard port 805 i8042.noloop [HW] Disable the AUX Loopback command while probing 806 for the AUX port 807 i8042.nomux [HW] Don't check presence of an active multiplexing 808 controller 809 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 810 controllers 811 i8042.panicblink= 812 [HW] Frequency with which keyboard LEDs should blink 813 when kernel panics (default is 0.5 sec) 814 i8042.reset [HW] Reset the controller during init and cleanup 815 i8042.unlock [HW] Unlock (ignore) the keylock 816 817 i810= [HW,DRM] 818 819 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 820 indicates that the driver is running on unsupported 821 hardware. 822 i8k.force [HW] Activate i8k driver even if SMM BIOS signature 823 does not match list of supported models. 824 i8k.power_status 825 [HW] Report power status in /proc/i8k 826 (disabled by default) 827 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 828 capability is set. 829 830 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter 831 See Documentation/mca.txt. 832 833 icn= [HW,ISDN] 834 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 835 836 ide= [HW] (E)IDE subsystem 837 Format: ide=nodma or ide=doubler 838 See Documentation/ide/ide.txt. 839 840 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed 841 See Documentation/ide/ide.txt. 842 843 idle= [X86] 844 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait 845 Poll forces a polling idle loop that can slightly improves the performance 846 of waking up a idle CPU, but will use a lot of power and make the system 847 run hot. Not recommended. 848 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose 849 to not use it because it doesn't save as much power as a normal idle 850 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same 851 as idle=poll. 852 idle=halt. Halt is forced to be used for CPU idle. 853 In such case C2/C3 won't be used again. 854 idle=nomwait. Disable mwait for CPU C-states 855 856 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 857 Claim all unknown PCI IDE storage controllers. 858 859 ignore_loglevel [KNL] 860 Ignore loglevel setting - this will print /all/ 861 kernel messages to the console. Useful for debugging. 862 863 ihash_entries= [KNL] 864 Set number of hash buckets for inode cache. 865 866 in2000= [HW,SCSI] 867 See header of drivers/scsi/in2000.c. 868 869 init= [KNL] 870 Format: <full_path> 871 Run specified binary instead of /sbin/init as init 872 process. 873 874 initcall_debug [KNL] Trace initcalls as they are executed. Useful 875 for working out where the kernel is dying during 876 startup. 877 878 initrd= [BOOT] Specify the location of the initial ramdisk 879 880 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 881 Format: <irq> 882 883 inttest= [IA64] 884 885 iommu= [x86] 886 off 887 force 888 noforce 889 biomerge 890 panic 891 nopanic 892 merge 893 nomerge 894 forcesac 895 soft 896 897 898 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 899 off 900 Disable intel iommu driver. 901 igfx_off [Default Off] 902 By default, gfx is mapped as normal device. If a gfx 903 device has a dedicated DMAR unit, the DMAR unit is 904 bypassed by not enabling DMAR with this option. In 905 this case, gfx device will use physical address for 906 DMA. 907 forcedac [x86_64] 908 With this option iommu will not optimize to look 909 for io virtual address below 32 bit forcing dual 910 address cycle on pci bus for cards supporting greater 911 than 32 bit addressing. The default is to look 912 for translation below 32 bit and if not available 913 then look in the higher range. 914 strict [Default Off] 915 With this option on every unmap_single operation will 916 result in a hardware IOTLB flush operation as opposed 917 to batching them for performance. 918 919 io_delay= [X86-32,X86-64] I/O delay method 920 0x80 921 Standard port 0x80 based delay 922 0xed 923 Alternate port 0xed based delay (needed on some systems) 924 udelay 925 Simple two microseconds delay 926 none 927 No delay 928 929 io7= [HW] IO7 for Marvel based alpha systems 930 See comment before marvel_specify_io7 in 931 arch/alpha/kernel/core_marvel.c. 932 933 ip= [IP_PNP] 934 See Documentation/filesystems/nfsroot.txt. 935 936 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards 937 See comment before ip2_setup() in 938 drivers/char/ip2/ip2base.c. 939 940 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller 941 See header of drivers/scsi/ips.c. 942 943 ports= [IP_VS_FTP] IPVS ftp helper module 944 Default is 21. 945 Up to 8 (IP_VS_APP_MAX_PORTS) ports 946 may be specified. 947 Format: <port>,<port>.... 948 949 irqfixup [HW] 950 When an interrupt is not handled search all handlers 951 for it. Intended to get systems with badly broken 952 firmware running. 953 954 irqpoll [HW] 955 When an interrupt is not handled search all handlers 956 for it. Also check all handlers each timer 957 interrupt. Intended to get systems with badly broken 958 firmware running. 959 960 isapnp= [ISAPNP] 961 Format: <RDP>,<reset>,<pci_scan>,<verbosity> 962 963 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. 964 Format: 965 <cpu number>,...,<cpu number> 966 or 967 <cpu number>-<cpu number> (must be a positive range in ascending order) 968 or a mixture 969 <cpu number>,...,<cpu number>-<cpu number> 970 This option can be used to specify one or more CPUs 971 to isolate from the general SMP balancing and scheduling 972 algorithms. The only way to move a process onto or off 973 an "isolated" CPU is via the CPU affinity syscalls. 974 <cpu number> begins at 0 and the maximum value is 975 "number of CPUs in system - 1". 976 977 This option is the preferred way to isolate CPUs. The 978 alternative -- manually setting the CPU mask of all 979 tasks in the system -- can cause problems and 980 suboptimal load balancer performance. 981 982 iucv= [HW,NET] 983 984 js= [HW,JOY] Analog joystick 985 See Documentation/input/joystick.txt. 986 987 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 988 specifies the amount of memory usable by the kernel 989 for non-movable allocations. The requested amount is 990 spread evenly throughout all nodes in the system. The 991 remaining memory in each node is used for Movable 992 pages. In the event, a node is too small to have both 993 kernelcore and Movable pages, kernelcore pages will 994 take priority and other nodes will have a larger number 995 of kernelcore pages. The Movable zone is used for the 996 allocation of pages that may be reclaimed or moved 997 by the page migration subsystem. This means that 998 HugeTLB pages may not be allocated from this zone. 999 Note that allocations like PTEs-from-HighMem still 1000 use the HighMem zone if it exists, and the Normal 1001 zone if it does not. 1002 1003 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter 1004 is similar to kernelcore except it specifies the 1005 amount of memory used for migratable allocations. 1006 If both kernelcore and movablecore is specified, 1007 then kernelcore will be at *least* the specified 1008 value but may be more. If movablecore on its own 1009 is specified, the administrator must be careful 1010 that the amount of memory usable for all allocations 1011 is not too small. 1012 1013 keepinitrd [HW,ARM] 1014 1015 kstack=N [X86-32,X86-64] Print N words from the kernel stack 1016 in oops dumps. 1017 1018 kgdboc= [HW] kgdb over consoles. 1019 Requires a tty driver that supports console polling. 1020 (only serial suported for now) 1021 Format: <serial_device>[,baud] 1022 1023 l2cr= [PPC] 1024 1025 l3cr= [PPC] 1026 1027 lapic [X86-32,APIC] Enable the local APIC even if BIOS 1028 disabled it. 1029 1030 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in 1031 C2 power state. 1032 1033 libata.dma= [LIBATA] DMA control 1034 libata.dma=0 Disable all PATA and SATA DMA 1035 libata.dma=1 PATA and SATA Disk DMA only 1036 libata.dma=2 ATAPI (CDROM) DMA only 1037 libata.dma=4 Compact Flash DMA only 1038 Combinations also work, so libata.dma=3 enables DMA 1039 for disks and CDROMs, but not CFs. 1040 1041 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 1042 when set. 1043 Format: <int> 1044 1045 libata.force= [LIBATA] Force configurations. The format is comma 1046 separated list of "[ID:]VAL" where ID is 1047 PORT[:DEVICE]. PORT and DEVICE are decimal numbers 1048 matching port, link or device. Basically, it matches 1049 the ATA ID string printed on console by libata. If 1050 the whole ID part is omitted, the last PORT and DEVICE 1051 values are used. If ID hasn't been specified yet, the 1052 configuration applies to all ports, links and devices. 1053 1054 If only DEVICE is omitted, the parameter applies to 1055 the port and all links and devices behind it. DEVICE 1056 number of 0 either selects the first device or the 1057 first fan-out link behind PMP device. It does not 1058 select the host link. DEVICE number of 15 selects the 1059 host link and device attached to it. 1060 1061 The VAL specifies the configuration to force. As long 1062 as there's no ambiguity shortcut notation is allowed. 1063 For example, both 1.5 and 1.5G would work for 1.5Gbps. 1064 The following configurations can be forced. 1065 1066 * Cable type: 40c, 80c, short40c, unk, ign or sata. 1067 Any ID with matching PORT is used. 1068 1069 * SATA link speed limit: 1.5Gbps or 3.0Gbps. 1070 1071 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 1072 udma[/][16,25,33,44,66,100,133] notation is also 1073 allowed. 1074 1075 * [no]ncq: Turn on or off NCQ. 1076 1077 * nohrst, nosrst, norst: suppress hard, soft 1078 and both resets. 1079 1080 If there are multiple matching configurations changing 1081 the same attribute, the last one is used. 1082 1083 load_ramdisk= [RAM] List of ramdisks to load from floppy 1084 See Documentation/ramdisk.txt. 1085 1086 lockd.nlm_grace_period=P [NFS] Assign grace period. 1087 Format: <integer> 1088 1089 lockd.nlm_tcpport=N [NFS] Assign TCP port. 1090 Format: <integer> 1091 1092 lockd.nlm_timeout=T [NFS] Assign timeout value. 1093 Format: <integer> 1094 1095 lockd.nlm_udpport=M [NFS] Assign UDP port. 1096 Format: <integer> 1097 1098 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 1099 Format: <irq> 1100 1101 loglevel= All Kernel Messages with a loglevel smaller than the 1102 console loglevel will be printed to the console. It can 1103 also be changed with klogd or other programs. The 1104 loglevels are defined as follows: 1105 1106 0 (KERN_EMERG) system is unusable 1107 1 (KERN_ALERT) action must be taken immediately 1108 2 (KERN_CRIT) critical conditions 1109 3 (KERN_ERR) error conditions 1110 4 (KERN_WARNING) warning conditions 1111 5 (KERN_NOTICE) normal but significant condition 1112 6 (KERN_INFO) informational 1113 7 (KERN_DEBUG) debug-level messages 1114 1115 log_buf_len=n Sets the size of the printk ring buffer, in bytes. 1116 Format: { n | nk | nM } 1117 n must be a power of two. The default size 1118 is set in the kernel config file. 1119 1120 logo.nologo [FB] Disables display of the built-in Linux logo. 1121 This may be used to provide more screen space for 1122 kernel log messages and is useful when debugging 1123 kernel boot problems. 1124 1125 lp=0 [LP] Specify parallel ports to use, e.g, 1126 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 1127 lp=reset first parallel port). 'lp=0' disables the 1128 lp=auto printer driver. 'lp=reset' (which can be 1129 specified in addition to the ports) causes 1130 attached printers to be reset. Using 1131 lp=port1,port2,... specifies the parallel ports 1132 to associate lp devices with, starting with 1133 lp0. A port specification may be 'none' to skip 1134 that lp device, or a parport name such as 1135 'parport0'. Specifying 'lp=auto' instead of a 1136 port specification list means that device IDs 1137 from each port should be examined, to see if 1138 an IEEE 1284-compliant printer is attached; if 1139 so, the driver will manage that printer. 1140 See also header of drivers/char/lp.c. 1141 1142 lpj=n [KNL] 1143 Sets loops_per_jiffy to given constant, thus avoiding 1144 time-consuming boot-time autodetection (up to 250 ms per 1145 CPU). 0 enables autodetection (default). To determine 1146 the correct value for your kernel, boot with normal 1147 autodetection and see what value is printed. Note that 1148 on SMP systems the preset will be applied to all CPUs, 1149 which is likely to cause problems if your CPUs need 1150 significantly divergent settings. An incorrect value 1151 will cause delays in the kernel to be wrong, leading to 1152 unpredictable I/O errors and other breakage. Although 1153 unlikely, in the extreme case this might damage your 1154 hardware. 1155 1156 ltpc= [NET] 1157 Format: <io>,<irq>,<dma> 1158 1159 mac5380= [HW,SCSI] Format: 1160 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> 1161 1162 machvec= [IA64] Force the use of a particular machine-vector 1163 (machvec) in a generic kernel. 1164 Example: machvec=hpzx1_swiotlb 1165 1166 max_loop= [LOOP] Maximum number of loopback devices that can 1167 be mounted 1168 Format: <1-256> 1169 1170 maxcpus= [SMP] Maximum number of processors that an SMP kernel 1171 should make use of. maxcpus=n : n >= 0 limits the 1172 kernel to using 'n' processors. n=0 is a special case, 1173 it is equivalent to "nosmp", which also disables 1174 the IO APIC. 1175 1176 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or 1177 equal to this physical address is ignored. 1178 1179 max_luns= [SCSI] Maximum number of LUNs to probe. 1180 Should be between 1 and 2^32-1. 1181 1182 max_report_luns= 1183 [SCSI] Maximum number of LUNs received. 1184 Should be between 1 and 16384. 1185 1186 mcatest= [IA-64] 1187 1188 mce [X86-32] Machine Check Exception 1189 1190 mce=option [X86-64] See Documentation/x86_64/boot-options.txt 1191 1192 md= [HW] RAID subsystems devices and level 1193 See Documentation/md.txt. 1194 1195 mdacon= [MDA] 1196 Format: <first>,<last> 1197 Specifies range of consoles to be captured by the MDA. 1198 1199 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 1200 Amount of memory to be used when the kernel is not able 1201 to see the whole system memory or for test. 1202 [X86-32] Use together with memmap= to avoid physical 1203 address space collisions. Without memmap= PCI devices 1204 could be placed at addresses belonging to unused RAM. 1205 1206 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 1207 memory. 1208 1209 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact 1210 E820 memory map, as specified by the user. 1211 Such memmap=exactmap lines can be constructed based on 1212 BIOS output or other requirements. See the memmap=nn@ss 1213 option description. 1214 1215 memmap=nn[KMG]@ss[KMG] 1216 [KNL] Force usage of a specific region of memory 1217 Region of memory to be used, from ss to ss+nn. 1218 1219 memmap=nn[KMG]#ss[KMG] 1220 [KNL,ACPI] Mark specific memory as ACPI data. 1221 Region of memory to be used, from ss to ss+nn. 1222 1223 memmap=nn[KMG]$ss[KMG] 1224 [KNL,ACPI] Mark specific memory as reserved. 1225 Region of memory to be used, from ss to ss+nn. 1226 Example: Exclude memory from 0x18690000-0x1869ffff 1227 memmap=64K$0x18690000 1228 or 1229 memmap=0x10000$0x18690000 1230 1231 memtest= [KNL,X86] Enable memtest 1232 Format: <integer> 1233 range: 0,4 : pattern number 1234 default : 0 <disable> 1235 1236 meye.*= [HW] Set MotionEye Camera parameters 1237 See Documentation/video4linux/meye.txt. 1238 1239 mfgpt_irq= [IA-32] Specify the IRQ to use for the 1240 Multi-Function General Purpose Timers on AMD Geode 1241 platforms. 1242 1243 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when 1244 the BIOS has incorrectly applied a workaround. TinyBIOS 1245 version 0.98 is known to be affected, 0.99 fixes the 1246 problem by letting the user disable the workaround. 1247 1248 mga= [HW,DRM] 1249 1250 mminit_loglevel= 1251 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this 1252 parameter allows control of the logging verbosity for 1253 the additional memory initialisation checks. A value 1254 of 0 disables mminit logging and a level of 4 will 1255 log everything. Information is printed at KERN_DEBUG 1256 so loglevel=8 may also need to be specified. 1257 1258 mousedev.tap_time= 1259 [MOUSE] Maximum time between finger touching and 1260 leaving touchpad surface for touch to be considered 1261 a tap and be reported as a left button click (for 1262 touchpads working in absolute mode only). 1263 Format: <msecs> 1264 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 1265 reporting absolute coordinates, such as tablets 1266 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 1267 reporting absolute coordinates, such as tablets 1268 1269 mpu401= [HW,OSS] 1270 Format: <io>,<irq> 1271 1272 MTD_Partition= [MTD] 1273 Format: <name>,<region-number>,<size>,<offset> 1274 1275 MTD_Region= [MTD] Format: 1276 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 1277 1278 mtdparts= [MTD] 1279 See drivers/mtd/cmdlinepart.c. 1280 1281 mtdset= [ARM] 1282 ARM/S3C2412 JIVE boot control 1283 1284 See arch/arm/mach-s3c2412/mach-jive.c 1285 1286 mtouchusb.raw_coordinates= 1287 [HW] Make the MicroTouch USB driver use raw coordinates 1288 ('y', default) or cooked coordinates ('n') 1289 1290 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 1291 1292 NCR_D700= [HW,SCSI] 1293 See header of drivers/scsi/NCR_D700.c. 1294 1295 ncr5380= [HW,SCSI] 1296 1297 ncr53c400= [HW,SCSI] 1298 1299 ncr53c400a= [HW,SCSI] 1300 1301 ncr53c406a= [HW,SCSI] 1302 1303 ncr53c8xx= [HW,SCSI] 1304 1305 netdev= [NET] Network devices parameters 1306 Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 1307 Note that mem_start is often overloaded to mean 1308 something different and driver-specific. 1309 This usage is only documented in each driver source 1310 file if at all. 1311 1312 nf_conntrack.acct= 1313 [NETFILTER] Enable connection tracking flow accounting 1314 0 to disable accounting 1315 1 to enable accounting 1316 Default value depends on CONFIG_NF_CT_ACCT that is 1317 going to be removed in 2.6.29. 1318 1319 nfsaddrs= [NFS] 1320 See Documentation/filesystems/nfsroot.txt. 1321 1322 nfsroot= [NFS] nfs root filesystem for disk-less boxes. 1323 See Documentation/filesystems/nfsroot.txt. 1324 1325 nfs.callback_tcpport= 1326 [NFS] set the TCP port on which the NFSv4 callback 1327 channel should listen. 1328 1329 nfs.idmap_cache_timeout= 1330 [NFS] set the maximum lifetime for idmapper cache 1331 entries. 1332 1333 nfs.enable_ino64= 1334 [NFS] enable 64-bit inode numbers. 1335 If zero, the NFS client will fake up a 32-bit inode 1336 number for the readdir() and stat() syscalls instead 1337 of returning the full 64-bit number. 1338 The default is to return 64-bit inode numbers. 1339 1340 nmi_debug= [KNL,AVR32] Specify one or more actions to take 1341 when a NMI is triggered. 1342 Format: [state][,regs][,debounce][,die] 1343 1344 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels 1345 1346 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths 1347 emulation library even if a 387 maths coprocessor 1348 is present. 1349 1350 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien 1351 caches in the slab allocator. Saves per-node memory, 1352 but will impact performance. 1353 1354 noalign [KNL,ARM] 1355 1356 noapic [SMP,APIC] Tells the kernel to not make use of any 1357 IOAPICs that may be present in the system. 1358 1359 nobats [PPC] Do not use BATs for mapping kernel lowmem 1360 on "Classic" PPC cores. 1361 1362 nocache [ARM] 1363 1364 nodelayacct [KNL] Disable per-task delay accounting 1365 1366 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. 1367 1368 noefi [X86-32,X86-64] Disable EFI runtime services support. 1369 1370 noexec [IA-64] 1371 1372 noexec [X86-32,X86-64] 1373 On X86-32 available only on PAE configured kernels. 1374 noexec=on: enable non-executable mappings (default) 1375 noexec=off: disable non-executable mappings 1376 1377 noexec32 [X86-64] 1378 This affects only 32-bit executables. 1379 noexec32=on: enable non-executable mappings (default) 1380 read doesn't imply executable mappings 1381 noexec32=off: disable non-executable mappings 1382 read implies executable mappings 1383 1384 nofxsr [BUGS=X86-32] Disables x86 floating point extended 1385 register save and restore. The kernel will only save 1386 legacy floating-point registers on task switch. 1387 1388 noclflush [BUGS=X86] Don't use the CLFLUSH instruction 1389 1390 nohlt [BUGS=ARM] 1391 1392 no-hlt [BUGS=X86-32] Tells the kernel that the hlt 1393 instruction doesn't work correctly and not to 1394 use it. 1395 1396 nohalt [IA-64] Tells the kernel not to use the power saving 1397 function PAL_HALT_LIGHT when idle. This increases 1398 power-consumption. On the positive side, it reduces 1399 interrupt wake-up latency, which may improve performance 1400 in certain environments such as networked servers or 1401 real-time systems. 1402 1403 nohz= [KNL] Boottime enable/disable dynamic ticks 1404 Valid arguments: on, off 1405 Default: on 1406 1407 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing 1408 1409 noirqdebug [X86-32] Disables the code which attempts to detect and 1410 disable unhandled interrupt sources. 1411 1412 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for 1413 broken timer IRQ sources. 1414 1415 noisapnp [ISAPNP] Disables ISA PnP code. 1416 1417 noinitrd [RAM] Tells the kernel not to load any configured 1418 initial RAM disk. 1419 1420 nointroute [IA-64] 1421 1422 nojitter [IA64] Disables jitter checking for ITC timers. 1423 1424 nolapic [X86-32,APIC] Do not enable or use the local APIC. 1425 1426 nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 1427 1428 noltlbs [PPC] Do not use large page/tlb entries for kernel 1429 lowmem mapping on PPC40x. 1430 1431 nomca [IA-64] Disable machine check abort handling 1432 1433 nomce [X86-32] Machine Check Exception 1434 1435 nomfgpt [X86-32] Disable Multi-Function General Purpose 1436 Timer usage (for AMD Geode machines). 1437 1438 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops 1439 1440 noreplace-smp [X86-32,SMP] Don't replace SMP instructions 1441 with UP alternatives 1442 1443 noresidual [PPC] Don't use residual data on PReP machines. 1444 1445 noresume [SWSUSP] Disables resume and restores original swap 1446 space. 1447 1448 no-scroll [VGA] Disables scrollback. 1449 This is required for the Braillex ib80-piezo Braille 1450 reader made by F.H. Papenmeier (Germany). 1451 1452 nosbagart [IA-64] 1453 1454 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. 1455 1456 nosmp [SMP] Tells an SMP kernel to act as a UP kernel, 1457 and disable the IO APIC. legacy for "maxcpus=0". 1458 1459 nosoftlockup [KNL] Disable the soft-lockup detector. 1460 1461 nosync [HW,M68K] Disables sync negotiation for all devices. 1462 1463 notsc [BUGS=X86-32] Disable Time Stamp Counter 1464 1465 nousb [USB] Disable the USB subsystem 1466 1467 nowb [ARM] 1468 1469 nptcg= [IA64] Override max number of concurrent global TLB 1470 purges which is reported from either PAL_VM_SUMMARY or 1471 SAL PALO. 1472 1473 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 1474 one of ['zone', 'node', 'default'] can be specified 1475 This can be set from sysctl after boot. 1476 See Documentation/sysctl/vm.txt for details. 1477 1478 nr_uarts= [SERIAL] maximum number of UARTs to be registered. 1479 1480 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands 1481 Rather than timing out after 20 ms if an EC 1482 command is not properly ACKed, override the length 1483 of the timeout. We have interrupts disabled while 1484 waiting for the ACK, so if this is set too high 1485 interrupts *may* be lost! 1486 1487 opl3= [HW,OSS] 1488 Format: <io> 1489 1490 oprofile.timer= [HW] 1491 Use timer interrupt instead of performance counters 1492 1493 osst= [HW,SCSI] SCSI Tape Driver 1494 Format: <buffer_size>,<write_threshold> 1495 See also Documentation/scsi/st.txt. 1496 1497 panic= [KNL] Kernel behaviour on panic 1498 Format: <timeout> 1499 1500 parkbd.port= [HW] Parallel port number the keyboard adapter is 1501 connected to, default is 0. 1502 Format: <parport#> 1503 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 1504 0 for XT, 1 for AT (default is AT). 1505 Format: <mode> 1506 1507 parport= [HW,PPT] Specify parallel ports. 0 disables. 1508 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 1509 Use 'auto' to force the driver to use any 1510 IRQ/DMA settings detected (the default is to 1511 ignore detected IRQ/DMA settings because of 1512 possible conflicts). You can specify the base 1513 address, IRQ, and DMA settings; IRQ and DMA 1514 should be numbers, or 'auto' (for using detected 1515 settings on that particular port), or 'nofifo' 1516 (to avoid using a FIFO even if it is detected). 1517 Parallel ports are assigned in the order they 1518 are specified on the command line, starting 1519 with parport0. 1520 1521 parport_init_mode= [HW,PPT] 1522 Configure VIA parallel port to operate in 1523 a specific mode. This is necessary on Pegasos 1524 computer where firmware has no options for setting 1525 up parallel port mode and sets it to spp. 1526 Currently this function knows 686a and 8231 chips. 1527 Format: [spp|ps2|epp|ecp|ecpepp] 1528 1529 pas2= [HW,OSS] Format: 1530 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16> 1531 1532 pas16= [HW,SCSI] 1533 See header of drivers/scsi/pas16.c. 1534 1535 pause_on_oops= 1536 Halt all CPUs after the first oops has been printed for 1537 the specified number of seconds. This is to be used if 1538 your oopses keep scrolling off the screen. 1539 1540 pcbit= [HW,ISDN] 1541 1542 pcd. [PARIDE] 1543 See header of drivers/block/paride/pcd.c. 1544 See also Documentation/paride.txt. 1545 1546 pci=option[,option...] [PCI] various PCI subsystem options: 1547 off [X86-32] don't probe for the PCI bus 1548 bios [X86-32] force use of PCI BIOS, don't access 1549 the hardware directly. Use this if your machine 1550 has a non-standard PCI host bridge. 1551 nobios [X86-32] disallow use of PCI BIOS, only direct 1552 hardware access methods are allowed. Use this 1553 if you experience crashes upon bootup and you 1554 suspect they are caused by the BIOS. 1555 conf1 [X86-32] Force use of PCI Configuration 1556 Mechanism 1. 1557 conf2 [X86-32] Force use of PCI Configuration 1558 Mechanism 2. 1559 noaer [PCIE] If the PCIEAER kernel config parameter is 1560 enabled, this kernel boot option can be used to 1561 disable the use of PCIE advanced error reporting. 1562 nodomains [PCI] Disable support for multiple PCI 1563 root domains (aka PCI segments, in ACPI-speak). 1564 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI 1565 Configuration 1566 nomsi [MSI] If the PCI_MSI kernel config parameter is 1567 enabled, this kernel boot option can be used to 1568 disable the use of MSI interrupts system-wide. 1569 biosirq [X86-32] Use PCI BIOS calls to get the interrupt 1570 routing table. These calls are known to be buggy 1571 on several machines and they hang the machine 1572 when used, but on other computers it's the only 1573 way to get the interrupt routing table. Try 1574 this option if the kernel is unable to allocate 1575 IRQs or discover secondary PCI buses on your 1576 motherboard. 1577 rom [X86-32] Assign address space to expansion ROMs. 1578 Use with caution as certain devices share 1579 address decoders between ROMs and other 1580 resources. 1581 norom [X86-32,X86_64] Do not assign address space to 1582 expansion ROMs that do not already have 1583 BIOS assigned address ranges. 1584 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be 1585 assigned automatically to PCI devices. You can 1586 make the kernel exclude IRQs of your ISA cards 1587 this way. 1588 pirqaddr=0xAAAAA [X86-32] Specify the physical address 1589 of the PIRQ table (normally generated 1590 by the BIOS) if it is outside the 1591 F0000h-100000h range. 1592 lastbus=N [X86-32] Scan all buses thru bus #N. Can be 1593 useful if the kernel is unable to find your 1594 secondary buses and you want to tell it 1595 explicitly which ones they are. 1596 assign-busses [X86-32] Always assign all PCI bus 1597 numbers ourselves, overriding 1598 whatever the firmware may have done. 1599 usepirqmask [X86-32] Honor the possible IRQ mask stored 1600 in the BIOS $PIR table. This is needed on 1601 some systems with broken BIOSes, notably 1602 some HP Pavilion N5400 and Omnibook XE3 1603 notebooks. This will have no effect if ACPI 1604 IRQ routing is enabled. 1605 noacpi [X86-32] Do not use ACPI for IRQ routing 1606 or for PCI scanning. 1607 use_crs [X86-32] Use _CRS for PCI resource 1608 allocation. 1609 routeirq Do IRQ routing for all PCI devices. 1610 This is normally done in pci_enable_device(), 1611 so this option is a temporary workaround 1612 for broken drivers that don't call it. 1613 skip_isa_align [X86] do not align io start addr, so can 1614 handle more pci cards 1615 firmware [ARM] Do not re-enumerate the bus but instead 1616 just use the configuration from the 1617 bootloader. This is currently used on 1618 IXP2000 systems where the bus has to be 1619 configured a certain way for adjunct CPUs. 1620 noearly [X86] Don't do any early type 1 scanning. 1621 This might help on some broken boards which 1622 machine check when some devices' config space 1623 is read. But various workarounds are disabled 1624 and some IOMMU drivers will not work. 1625 bfsort Sort PCI devices into breadth-first order. 1626 This sorting is done to get a device 1627 order compatible with older (<= 2.4) kernels. 1628 nobfsort Don't sort PCI devices into breadth-first order. 1629 cbiosize=nn[KMG] The fixed amount of bus space which is 1630 reserved for the CardBus bridge's IO window. 1631 The default value is 256 bytes. 1632 cbmemsize=nn[KMG] The fixed amount of bus space which is 1633 reserved for the CardBus bridge's memory 1634 window. The default value is 64 megabytes. 1635 1636 pcmv= [HW,PCMCIA] BadgePAD 4 1637 1638 pd. [PARIDE] 1639 See Documentation/paride.txt. 1640 1641 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 1642 boot time. 1643 Format: { 0 | 1 } 1644 See arch/parisc/kernel/pdc_chassis.c 1645 1646 pf. [PARIDE] 1647 See Documentation/paride.txt. 1648 1649 pg. [PARIDE] 1650 See Documentation/paride.txt. 1651 1652 pirq= [SMP,APIC] Manual mp-table setup 1653 See Documentation/i386/IO-APIC.txt. 1654 1655 plip= [PPT,NET] Parallel port network link 1656 Format: { parport<nr> | timid | 0 } 1657 See also Documentation/parport.txt. 1658 1659 pmtmr= [X86] Manual setup of pmtmr I/O Port. 1660 Override pmtimer IOPort with a hex value. 1661 e.g. pmtmr=0x508 1662 1663 pnpacpi= [ACPI] 1664 { off } 1665 1666 pnpbios= [ISAPNP] 1667 { on | off | curr | res | no-curr | no-res } 1668 1669 pnp_reserve_irq= 1670 [ISAPNP] Exclude IRQs for the autoconfiguration 1671 1672 pnp_reserve_dma= 1673 [ISAPNP] Exclude DMAs for the autoconfiguration 1674 1675 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 1676 Ranges are in pairs (I/O port base and size). 1677 1678 pnp_reserve_mem= 1679 [ISAPNP] Exclude memory regions for the 1680 autoconfiguration. 1681 Ranges are in pairs (memory base and size). 1682 1683 print-fatal-signals= 1684 [KNL] debug: print fatal signals 1685 print-fatal-signals=1: print segfault info to 1686 the kernel console. 1687 default: off. 1688 1689 printk.time= Show timing data prefixed to each printk message line 1690 Format: <bool> (1/Y/y=enable, 0/N/n=disable) 1691 1692 profile= [KNL] Enable kernel profiling via /proc/profile 1693 Format: [schedule,]<number> 1694 Param: "schedule" - profile schedule points. 1695 Param: <number> - step/bucket size as a power of 2 for 1696 statistical time based profiling. 1697 Param: "sleep" - profile D-state sleeping (millisecs). 1698 Requires CONFIG_SCHEDSTATS 1699 Param: "kvm" - profile VM exits. 1700 1701 processor.max_cstate= [HW,ACPI] 1702 Limit processor to maximum C-state 1703 max_cstate=9 overrides any DMI blacklist limit. 1704 1705 processor.nocst [HW,ACPI] 1706 Ignore the _CST method to determine C-states, 1707 instead using the legacy FADT method 1708 1709 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 1710 before loading. 1711 See Documentation/ramdisk.txt. 1712 1713 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 1714 probe for; one of (bare|imps|exps|lifebook|any). 1715 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 1716 per second. 1717 psmouse.resetafter= [HW,MOUSE] 1718 Try to reset the device after so many bad packets 1719 (0 = never). 1720 psmouse.resolution= 1721 [HW,MOUSE] Set desired mouse resolution, in dpi. 1722 psmouse.smartscroll= 1723 [HW,MOUSE] Controls Logitech smartscroll autorepeat. 1724 0 = disabled, 1 = enabled (default). 1725 1726 pss= [HW,OSS] Personal Sound System (ECHO ESC614) 1727 Format: 1728 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> 1729 1730 pt. [PARIDE] 1731 See Documentation/paride.txt. 1732 1733 pty.legacy_count= 1734 [KNL] Number of legacy pty's. Overwrites compiled-in 1735 default number. 1736 1737 quiet [KNL] Disable most log messages 1738 1739 r128= [HW,DRM] 1740 1741 raid= [HW,RAID] 1742 See Documentation/md.txt. 1743 1744 ramdisk_blocksize= [RAM] 1745 See Documentation/ramdisk.txt. 1746 1747 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 1748 See Documentation/ramdisk.txt. 1749 1750 rcupdate.blimit= [KNL,BOOT] 1751 Set maximum number of finished RCU callbacks to process 1752 in one batch. 1753 1754 rcupdate.qhimark= [KNL,BOOT] 1755 Set threshold of queued 1756 RCU callbacks over which batch limiting is disabled. 1757 1758 rcupdate.qlowmark= [KNL,BOOT] 1759 Set threshold of queued RCU callbacks below which 1760 batch limiting is re-enabled. 1761 1762 rdinit= [KNL] 1763 Format: <full_path> 1764 Run specified binary instead of /init from the ramdisk, 1765 used for early userspace startup. See initrd. 1766 1767 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode 1768 Format: <reboot_mode>[,<reboot_mode2>[,...]] 1769 See arch/*/kernel/reboot.c or arch/*/kernel/process.c 1770 1771 relax_domain_level= 1772 [KNL, SMP] Set scheduler's default relax_domain_level. 1773 See Documentation/cpusets.txt. 1774 1775 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area 1776 1777 reservetop= [X86-32] 1778 Format: nn[KMG] 1779 Reserves a hole at the top of the kernel virtual 1780 address space. 1781 1782 reset_devices [KNL] Force drivers to reset the underlying device 1783 during initialization. 1784 1785 resume= [SWSUSP] 1786 Specify the partition device for software suspend 1787 1788 resume_offset= [SWSUSP] 1789 Specify the offset from the beginning of the partition 1790 given by "resume=" at which the swap header is located, 1791 in <PAGE_SIZE> units (needed only for swap files). 1792 See Documentation/power/swsusp-and-swap-files.txt 1793 1794 retain_initrd [RAM] Keep initrd memory after extraction 1795 1796 rhash_entries= [KNL,NET] 1797 Set number of hash buckets for route cache 1798 1799 riscom8= [HW,SERIAL] 1800 Format: <io_board1>[,<io_board2>[,...<io_boardN>]] 1801 1802 ro [KNL] Mount root device read-only on boot 1803 1804 root= [KNL] Root filesystem 1805 1806 rootdelay= [KNL] Delay (in seconds) to pause before attempting to 1807 mount the root filesystem 1808 1809 rootflags= [KNL] Set root filesystem mount option string 1810 1811 rootfstype= [KNL] Set root filesystem type 1812 1813 rootwait [KNL] Wait (indefinitely) for root device to show up. 1814 Useful for devices that are detected asynchronously 1815 (e.g. USB and MMC devices). 1816 1817 root_plug.vendor_id= 1818 [ROOTPLUG] Override the default vendor ID 1819 1820 root_plug.product_id= 1821 [ROOTPLUG] Override the default product ID 1822 1823 root_plug.debug= 1824 [ROOTPLUG] Enable debugging output 1825 1826 rw [KNL] Mount root device read-write on boot 1827 1828 S [KNL] Run init in single mode 1829 1830 sa1100ir [NET] 1831 See drivers/net/irda/sa1100_ir.c. 1832 1833 sbni= [NET] Granch SBNI12 leased line adapter 1834 1835 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver 1836 Format: <io>[,<timeout>[,<isapnp>]] 1837 1838 scsi_debug_*= [SCSI] 1839 See drivers/scsi/scsi_debug.c. 1840 1841 scsi_default_dev_flags= 1842 [SCSI] SCSI default device flags 1843 Format: <integer> 1844 1845 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model 1846 Format: <vendor>:<model>:<flags> 1847 (flags are integer value) 1848 1849 scsi_logging_level= [SCSI] a bit mask of logging levels 1850 See drivers/scsi/scsi_logging.h for bits. Also 1851 settable via sysctl at dev.scsi.logging_level 1852 (/proc/sys/dev/scsi/logging_level). 1853 There is also a nice 'scsi_logging_level' script in the 1854 S390-tools package, available for download at 1855 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html 1856 1857 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are 1858 discovered. async scans them in kernel threads, 1859 allowing boot to proceed. none ignores them, expecting 1860 user space to do the scan. 1861 1862 selinux [SELINUX] Disable or enable SELinux at boot time. 1863 Format: { "0" | "1" } 1864 See security/selinux/Kconfig help text. 1865 0 -- disable. 1866 1 -- enable. 1867 Default value is set via kernel config option. 1868 If enabled at boot time, /selinux/disable can be used 1869 later to disable prior to initial policy load. 1870 1871 selinux_compat_net = 1872 [SELINUX] Set initial selinux_compat_net flag value. 1873 Format: { "0" | "1" } 1874 0 -- use new secmark-based packet controls 1875 1 -- use legacy packet controls 1876 Default value is 0 (preferred). 1877 Value can be changed at runtime via 1878 /selinux/compat_net. 1879 1880 serialnumber [BUGS=X86-32] 1881 1882 shapers= [NET] 1883 Maximal number of shapers. 1884 1885 sim710= [SCSI,HW] 1886 See header of drivers/scsi/sim710.c. 1887 1888 simeth= [IA-64] 1889 simscsi= 1890 1891 slram= [HW,MTD] 1892 1893 slub_debug[=options[,slabs]] [MM, SLUB] 1894 Enabling slub_debug allows one to determine the 1895 culprit if slab objects become corrupted. Enabling 1896 slub_debug can create guard zones around objects and 1897 may poison objects when not in use. Also tracks the 1898 last alloc / free. For more information see 1899 Documentation/vm/slub.txt. 1900 1901 slub_max_order= [MM, SLUB] 1902 Determines the maximum allowed order for slabs. 1903 A high setting may cause OOMs due to memory 1904 fragmentation. For more information see 1905 Documentation/vm/slub.txt. 1906 1907 slub_min_objects= [MM, SLUB] 1908 The minimum number of objects per slab. SLUB will 1909 increase the slab order up to slub_max_order to 1910 generate a sufficiently large slab able to contain 1911 the number of objects indicated. The higher the number 1912 of objects the smaller the overhead of tracking slabs 1913 and the less frequently locks need to be acquired. 1914 For more information see Documentation/vm/slub.txt. 1915 1916 slub_min_order= [MM, SLUB] 1917 Determines the mininum page order for slabs. Must be 1918 lower than slub_max_order. 1919 For more information see Documentation/vm/slub.txt. 1920 1921 slub_nomerge [MM, SLUB] 1922 Disable merging of slabs with similar size. May be 1923 necessary if there is some reason to distinguish 1924 allocs to different slabs. Debug options disable 1925 merging on their own. 1926 For more information see Documentation/vm/slub.txt. 1927 1928 smart2= [HW] 1929 Format: <io1>[,<io2>[,...,<io8>]] 1930 1931 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only 1932 attempt to substitute SMP alternatives once at boot. 1933 1934 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 1935 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 1936 smsc-ircc2.ircc_sir= [HW] SIR base I/O port 1937 smsc-ircc2.ircc_fir= [HW] FIR base I/O port 1938 smsc-ircc2.ircc_irq= [HW] IRQ line 1939 smsc-ircc2.ircc_dma= [HW] DMA channel 1940 smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 1941 0: Toshiba Satellite 1800 (GP data pin select) 1942 1: Fast pin select (default) 1943 2: ATC IRMode 1944 1945 snd-ad1816a= [HW,ALSA] 1946 1947 snd-ad1848= [HW,ALSA] 1948 1949 snd-ali5451= [HW,ALSA] 1950 1951 snd-als100= [HW,ALSA] 1952 1953 snd-als4000= [HW,ALSA] 1954 1955 snd-azt2320= [HW,ALSA] 1956 1957 snd-cmi8330= [HW,ALSA] 1958 1959 snd-cmipci= [HW,ALSA] 1960 1961 snd-cs4231= [HW,ALSA] 1962 1963 snd-cs4232= [HW,ALSA] 1964 1965 snd-cs4236= [HW,ALSA] 1966 1967 snd-cs4281= [HW,ALSA] 1968 1969 snd-cs46xx= [HW,ALSA] 1970 1971 snd-dt019x= [HW,ALSA] 1972 1973 snd-dummy= [HW,ALSA] 1974 1975 snd-emu10k1= [HW,ALSA] 1976 1977 snd-ens1370= [HW,ALSA] 1978 1979 snd-ens1371= [HW,ALSA] 1980 1981 snd-es968= [HW,ALSA] 1982 1983 snd-es1688= [HW,ALSA] 1984 1985 snd-es18xx= [HW,ALSA] 1986 1987 snd-es1938= [HW,ALSA] 1988 1989 snd-es1968= [HW,ALSA] 1990 1991 snd-fm801= [HW,ALSA] 1992 1993 snd-gusclassic= [HW,ALSA] 1994 1995 snd-gusextreme= [HW,ALSA] 1996 1997 snd-gusmax= [HW,ALSA] 1998 1999 snd-hdsp= [HW,ALSA] 2000 2001 snd-ice1712= [HW,ALSA] 2002 2003 snd-intel8x0= [HW,ALSA] 2004 2005 snd-interwave= [HW,ALSA] 2006 2007 snd-interwave-stb= 2008 [HW,ALSA] 2009 2010 snd-korg1212= [HW,ALSA] 2011 2012 snd-maestro3= [HW,ALSA] 2013 2014 snd-mpu401= [HW,ALSA] 2015 2016 snd-mtpav= [HW,ALSA] 2017 2018 snd-nm256= [HW,ALSA] 2019 2020 snd-opl3sa2= [HW,ALSA] 2021 2022 snd-opti92x-ad1848= 2023 [HW,ALSA] 2024 2025 snd-opti92x-cs4231= 2026 [HW,ALSA] 2027 2028 snd-opti93x= [HW,ALSA] 2029 2030 snd-pmac= [HW,ALSA] 2031 2032 snd-rme32= [HW,ALSA] 2033 2034 snd-rme96= [HW,ALSA] 2035 2036 snd-rme9652= [HW,ALSA] 2037 2038 snd-sb8= [HW,ALSA] 2039 2040 snd-sb16= [HW,ALSA] 2041 2042 snd-sbawe= [HW,ALSA] 2043 2044 snd-serial= [HW,ALSA] 2045 2046 snd-sgalaxy= [HW,ALSA] 2047 2048 snd-sonicvibes= [HW,ALSA] 2049 2050 snd-sun-amd7930= 2051 [HW,ALSA] 2052 2053 snd-sun-cs4231= [HW,ALSA] 2054 2055 snd-trident= [HW,ALSA] 2056 2057 snd-usb-audio= [HW,ALSA,USB] 2058 2059 snd-via82xx= [HW,ALSA] 2060 2061 snd-virmidi= [HW,ALSA] 2062 2063 snd-wavefront= [HW,ALSA] 2064 2065 snd-ymfpci= [HW,ALSA] 2066 2067 softlockup_panic= 2068 [KNL] Should the soft-lockup detector generate panics. 2069 2070 sonypi.*= [HW] Sony Programmable I/O Control Device driver 2071 See Documentation/sonypi.txt 2072 2073 specialix= [HW,SERIAL] Specialix multi-serial port adapter 2074 See Documentation/specialix.txt. 2075 2076 spia_io_base= [HW,MTD] 2077 spia_fio_base= 2078 spia_pedr= 2079 spia_peddr= 2080 2081 sscape= [HW,OSS] 2082 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq> 2083 2084 st= [HW,SCSI] SCSI tape parameters (buffers, etc.) 2085 See Documentation/scsi/st.txt. 2086 2087 sti= [PARISC,HW] 2088 Format: <num> 2089 Set the STI (builtin display/keyboard on the HP-PARISC 2090 machines) console (graphic card) which should be used 2091 as the initial boot-console. 2092 See also comment in drivers/video/console/sticore.c. 2093 2094 sti_font= [HW] 2095 See comment in drivers/video/console/sticore.c. 2096 2097 stifb= [HW] 2098 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 2099 2100 sunrpc.pool_mode= 2101 [NFS] 2102 Control how the NFS server code allocates CPUs to 2103 service thread pools. Depending on how many NICs 2104 you have and where their interrupts are bound, this 2105 option will affect which CPUs will do NFS serving. 2106 Note: this parameter cannot be changed while the 2107 NFS server is running. 2108 2109 auto the server chooses an appropriate mode 2110 automatically using heuristics 2111 global a single global pool contains all CPUs 2112 percpu one pool for each CPU 2113 pernode one pool for each NUMA node (equivalent 2114 to global on non-NUMA machines) 2115 2116 swiotlb= [IA-64] Number of I/O TLB slabs 2117 2118 switches= [HW,M68k] 2119 2120 sym53c416= [HW,SCSI] 2121 See header of drivers/scsi/sym53c416.c. 2122 2123 sysrq_always_enabled 2124 [KNL] 2125 Ignore sysrq setting - this boot parameter will 2126 neutralize any effect of /proc/sys/kernel/sysrq. 2127 Useful for debugging. 2128 2129 t128= [HW,SCSI] 2130 See header of drivers/scsi/t128.c. 2131 2132 tdfx= [HW,DRM] 2133 2134 test_suspend= [SUSPEND] 2135 Specify "mem" (for Suspend-to-RAM) or "standby" (for 2136 standby suspend) as the system sleep state to briefly 2137 enter during system startup. The system is woken from 2138 this state using a wakeup-capable RTC alarm. 2139 2140 thash_entries= [KNL,NET] 2141 Set number of hash buckets for TCP connection 2142 2143 thermal.act= [HW,ACPI] 2144 -1: disable all active trip points in all thermal zones 2145 <degrees C>: override all lowest active trip points 2146 2147 thermal.crt= [HW,ACPI] 2148 -1: disable all critical trip points in all thermal zones 2149 <degrees C>: lower all critical trip points 2150 2151 thermal.nocrt= [HW,ACPI] 2152 Set to disable actions on ACPI thermal zone 2153 critical and hot trip points. 2154 2155 thermal.off= [HW,ACPI] 2156 1: disable ACPI thermal control 2157 2158 thermal.psv= [HW,ACPI] 2159 -1: disable all passive trip points 2160 <degrees C>: override all passive trip points to this value 2161 2162 thermal.tzp= [HW,ACPI] 2163 Specify global default ACPI thermal zone polling rate 2164 <deci-seconds>: poll all this frequency 2165 0: no polling (default) 2166 2167 tmscsim= [HW,SCSI] 2168 See comment before function dc390_setup() in 2169 drivers/scsi/tmscsim.c. 2170 2171 tp720= [HW,PS2] 2172 2173 trix= [HW,OSS] MediaTrix AudioTrix Pro 2174 Format: 2175 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq> 2176 2177 turbografx.map[2|3]= [HW,JOY] 2178 TurboGraFX parallel port interface 2179 Format: 2180 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 2181 See also Documentation/input/joystick-parport.txt 2182 2183 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter 2184 See header of drivers/scsi/u14-34f.c. 2185 2186 uart401= [HW,OSS] 2187 Format: <io>,<irq> 2188 2189 uart6850= [HW,OSS] 2190 Format: <io>,<irq> 2191 2192 uhci-hcd.ignore_oc= 2193 [USB] Ignore overcurrent events (default N). 2194 Some badly-designed motherboards generate lots of 2195 bogus events, for ports that aren't wired to 2196 anything. Set this parameter to avoid log spamming. 2197 Note that genuine overcurrent events won't be 2198 reported either. 2199 2200 unknown_nmi_panic 2201 [X86-32,X86-64] 2202 Set unknown_nmi_panic=1 early on boot. 2203 2204 usbcore.autosuspend= 2205 [USB] The autosuspend time delay (in seconds) used 2206 for newly-detected USB devices (default 2). This 2207 is the time required before an idle device will be 2208 autosuspended. Devices for which the delay is set 2209 to a negative value won't be autosuspended at all. 2210 2211 usbhid.mousepoll= 2212 [USBHID] The interval which mice are to be polled at. 2213 2214 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in 2215 kernel's map of available physical RAM. 2216 2217 vdso= [X86-32,SH,x86-64] 2218 vdso=2: enable compat VDSO (default with COMPAT_VDSO) 2219 vdso=1: enable VDSO (default) 2220 vdso=0: disable VDSO mapping 2221 2222 vdso32= [X86-32,X86-64] 2223 vdso32=2: enable compat VDSO (default with COMPAT_VDSO) 2224 vdso32=1: enable 32-bit VDSO (default) 2225 vdso32=0: disable 32-bit VDSO mapping 2226 2227 vector= [IA-64,SMP] 2228 vector=percpu: enable percpu vector domain 2229 2230 video= [FB] Frame buffer configuration 2231 See Documentation/fb/modedb.txt. 2232 2233 vga= [BOOT,X86-32] Select a particular video mode 2234 See Documentation/i386/boot.txt and 2235 Documentation/svga.txt. 2236 Use vga=ask for menu. 2237 This is actually a boot loader parameter; the value is 2238 passed to the kernel using a special protocol. 2239 2240 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 2241 size of <nn>. This can be used to increase the 2242 minimum size (128MB on x86). It can also be used to 2243 decrease the size and leave more room for directly 2244 mapped kernel RAM. 2245 2246 vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 2247 Format: <command> 2248 2249 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 2250 Format: <command> 2251 2252 vmpoff= [KNL,S390] Perform z/VM CP command after power off. 2253 Format: <command> 2254 2255 waveartist= [HW,OSS] 2256 Format: <io>,<irq>,<dma>,<dma2> 2257 2258 wd33c93= [HW,SCSI] 2259 See header of drivers/scsi/wd33c93.c. 2260 2261 wd7000= [HW,SCSI] 2262 See header of drivers/scsi/wd7000.c. 2263 2264 wdt= [WDT] Watchdog 2265 See Documentation/watchdog/wdt.txt. 2266 2267 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. 2268 xd_geo= See header of drivers/block/xd.c. 2269 2270 xirc2ps_cs= [NET,PCMCIA] 2271 Format: 2272 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 2273 2274 norandmaps Don't use address space randomization 2275 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space 2276 2277______________________________________________________________________ 2278 2279TODO: 2280 2281 Add documentation for ALSA options. 2282 Add more DRM drivers.