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 20Hyphens (dashes) and underscores are equivalent in parameter names, so 21 log_buf_len=1M print-fatal-signals=1 22can also be entered as 23 log-buf-len=1M print_fatal_signals=1 24 25 26This document may not be entirely up to date and comprehensive. The command 27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable 28module. Loadable modules, after being loaded into the running kernel, also 29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these 30parameters may be changed at runtime by the command 31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}". 32 33The parameters listed below are only valid if certain kernel build options were 34enabled and if respective hardware is present. The text in square brackets at 35the beginning of each description states the restrictions within which a 36parameter is applicable: 37 38 ACPI ACPI support is enabled. 39 AGP AGP (Accelerated Graphics Port) is enabled. 40 ALSA ALSA sound support is enabled. 41 APIC APIC support is enabled. 42 APM Advanced Power Management support is enabled. 43 AVR32 AVR32 architecture is enabled. 44 AX25 Appropriate AX.25 support is enabled. 45 BLACKFIN Blackfin architecture is enabled. 46 DRM Direct Rendering Management support is enabled. 47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled 48 EFI EFI Partitioning (GPT) is enabled 49 EIDE EIDE/ATAPI support is enabled. 50 FB The frame buffer device is enabled. 51 HW Appropriate hardware is enabled. 52 IA-64 IA-64 architecture is enabled. 53 IMA Integrity measurement architecture is enabled. 54 IOSCHED More than one I/O scheduler is enabled. 55 IP_PNP IP DHCP, BOOTP, or RARP is enabled. 56 ISAPNP ISA PnP code is enabled. 57 ISDN Appropriate ISDN support is enabled. 58 JOY Appropriate joystick support is enabled. 59 KMEMTRACE kmemtrace is enabled. 60 LIBATA Libata driver is enabled 61 LP Printer support is enabled. 62 LOOP Loopback device support is enabled. 63 M68k M68k architecture is enabled. 64 These options have more detailed description inside of 65 Documentation/m68k/kernel-options.txt. 66 MCA MCA bus support is enabled. 67 MDA MDA console support is enabled. 68 MOUSE Appropriate mouse support is enabled. 69 MSI Message Signaled Interrupts (PCI). 70 MTD MTD (Memory Technology Device) support is enabled. 71 NET Appropriate network support is enabled. 72 NUMA NUMA support is enabled. 73 GENERIC_TIME The generic timeofday code is enabled. 74 NFS Appropriate NFS support is enabled. 75 OSS OSS sound support is enabled. 76 PV_OPS A paravirtualized kernel is enabled. 77 PARIDE The ParIDE (parallel port IDE) subsystem is enabled. 78 PARISC The PA-RISC architecture is enabled. 79 PCI PCI bus support is enabled. 80 PCIE PCI Express support is enabled. 81 PCMCIA The PCMCIA subsystem is enabled. 82 PNP Plug & Play support is enabled. 83 PPC PowerPC architecture is enabled. 84 PPT Parallel port support is enabled. 85 PS2 Appropriate PS/2 support is enabled. 86 RAM RAM disk support is enabled. 87 ROOTPLUG The example Root Plug LSM is enabled. 88 S390 S390 architecture is enabled. 89 SCSI Appropriate SCSI support is enabled. 90 A lot of drivers has their options described inside of 91 Documentation/scsi/. 92 SECURITY Different security models are enabled. 93 SELINUX SELinux support is enabled. 94 SERIAL Serial support is enabled. 95 SH SuperH architecture is enabled. 96 SMP The kernel is an SMP kernel. 97 SPARC Sparc architecture is enabled. 98 SWSUSP Software suspend (hibernation) is enabled. 99 SUSPEND System suspend states are enabled. 100 FTRACE Function tracing enabled. 101 TS Appropriate touchscreen support is enabled. 102 UMS USB Mass Storage support is enabled. 103 USB USB support is enabled. 104 USBHID USB Human Interface Device support is enabled. 105 V4L Video For Linux support is enabled. 106 VGA The VGA console has been enabled. 107 VT Virtual terminal support is enabled. 108 WDT Watchdog support is enabled. 109 XT IBM PC/XT MFM hard disk support is enabled. 110 X86-32 X86-32, aka i386 architecture is enabled. 111 X86-64 X86-64 architecture is enabled. 112 More X86-64 boot options can be found in 113 Documentation/x86/x86_64/boot-options.txt . 114 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64) 115 116In addition, the following text indicates that the option: 117 118 BUGS= Relates to possible processor bugs on the said processor. 119 KNL Is a kernel start-up parameter. 120 BOOT Is a boot loader parameter. 121 122Parameters denoted with BOOT are actually interpreted by the boot 123loader, and have no meaning to the kernel directly. 124Do not modify the syntax of boot loader parameters without extreme 125need or coordination with <Documentation/x86/boot.txt>. 126 127There are also arch-specific kernel-parameters not documented here. 128See for example <Documentation/x86/x86_64/boot-options.txt>. 129 130Note that ALL kernel parameters listed below are CASE SENSITIVE, and that 131a trailing = on the name of any parameter states that that parameter will 132be entered as an environment variable, whereas its absence indicates that 133it will appear as a kernel argument readable via /proc/cmdline by programs 134running once the system is up. 135 136The number of kernel parameters is not limited, but the length of the 137complete command line (parameters including spaces etc.) is limited to 138a fixed number of characters. This limit depends on the architecture 139and is between 256 and 4096 characters. It is defined in the file 140./include/asm/setup.h as COMMAND_LINE_SIZE. 141 142 143 acpi= [HW,ACPI,X86] 144 Advanced Configuration and Power Interface 145 Format: { force | off | ht | strict | noirq | rsdt } 146 force -- enable ACPI if default was off 147 off -- disable ACPI if default was on 148 noirq -- do not use ACPI for IRQ routing 149 ht -- run only enough ACPI to enable Hyper Threading 150 strict -- Be less tolerant of platforms that are not 151 strictly ACPI specification compliant. 152 rsdt -- prefer RSDT over (default) XSDT 153 154 See also Documentation/power/pm.txt, pci=noacpi 155 156 acpi_apic_instance= [ACPI, IOAPIC] 157 Format: <int> 158 2: use 2nd APIC table, if available 159 1,0: use 1st APIC table 160 default: 0 161 162 acpi_backlight= [HW,ACPI] 163 acpi_backlight=vendor 164 acpi_backlight=video 165 If set to vendor, prefer vendor specific driver 166 (e.g. thinkpad_acpi, sony_acpi, etc.) instead 167 of the ACPI video.ko driver. 168 169 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] 170 acpi.debug_level= [HW,ACPI,ACPI_DEBUG] 171 Format: <int> 172 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI 173 debug output. Bits in debug_layer correspond to a 174 _COMPONENT in an ACPI source file, e.g., 175 #define _COMPONENT ACPI_PCI_COMPONENT 176 Bits in debug_level correspond to a level in 177 ACPI_DEBUG_PRINT statements, e.g., 178 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... 179 The debug_level mask defaults to "info". See 180 Documentation/acpi/debug.txt for more information about 181 debug layers and levels. 182 183 Enable processor driver info messages: 184 acpi.debug_layer=0x20000000 185 Enable PCI/PCI interrupt routing info messages: 186 acpi.debug_layer=0x400000 187 Enable AML "Debug" output, i.e., stores to the Debug 188 object while interpreting AML: 189 acpi.debug_layer=0xffffffff acpi.debug_level=0x2 190 Enable all messages related to ACPI hardware: 191 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff 192 193 Some values produce so much output that the system is 194 unusable. The "log_buf_len" parameter may be useful 195 if you need to capture more output. 196 197 acpi_display_output= [HW,ACPI] 198 acpi_display_output=vendor 199 acpi_display_output=video 200 See above. 201 202 acpi_irq_balance [HW,ACPI] 203 ACPI will balance active IRQs 204 default in APIC mode 205 206 acpi_irq_nobalance [HW,ACPI] 207 ACPI will not move active IRQs (default) 208 default in PIC mode 209 210 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA 211 Format: <irq>,<irq>... 212 213 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for 214 use by PCI 215 Format: <irq>,<irq>... 216 217 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT 218 219 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS 220 Format: To spoof as Windows 98: ="Microsoft Windows" 221 222 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings 223 acpi_osi="string1" # add string1 -- only one string 224 acpi_osi="!string2" # remove built-in string2 225 acpi_osi= # disable all strings 226 227 acpi_pm_good [X86] 228 Override the pmtimer bug detection: force the kernel 229 to assume that this machine's pmtimer latches its value 230 and always returns good values. 231 232 acpi.power_nocheck= [HW,ACPI] 233 Format: 1/0 enable/disable the check of power state. 234 On some bogus BIOS the _PSC object/_STA object of 235 power resource can't return the correct device power 236 state. In such case it is unneccessary to check its 237 power state again in power transition. 238 1 : disable the power state check 239 240 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode 241 Format: { level | edge | high | low } 242 243 acpi_serialize [HW,ACPI] force serialization of AML methods 244 245 acpi_skip_timer_override [HW,ACPI] 246 Recognize and ignore IRQ0/pin2 Interrupt Override. 247 For broken nForce2 BIOS resulting in XT-PIC timer. 248 249 acpi_sleep= [HW,ACPI] Sleep options 250 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, 251 old_ordering, s4_nonvs } 252 See Documentation/power/video.txt for information on 253 s3_bios and s3_mode. 254 s3_beep is for debugging; it makes the PC's speaker beep 255 as soon as the kernel's real-mode entry point is called. 256 s4_nohwsig prevents ACPI hardware signature from being 257 used during resume from hibernation. 258 old_ordering causes the ACPI 1.0 ordering of the _PTS 259 control method, with respect to putting devices into 260 low power states, to be enforced (the ACPI 2.0 ordering 261 of _PTS is used by default). 262 s4_nonvs prevents the kernel from saving/restoring the 263 ACPI NVS memory during hibernation. 264 265 acpi_use_timer_override [HW,ACPI] 266 Use timer override. For some broken Nvidia NF5 boards 267 that require a timer override, but don't have HPET 268 269 acpi_enforce_resources= [ACPI] 270 { strict | lax | no } 271 Check for resource conflicts between native drivers 272 and ACPI OperationRegions (SystemIO and SystemMemory 273 only). IO ports and memory declared in ACPI might be 274 used by the ACPI subsystem in arbitrary AML code and 275 can interfere with legacy drivers. 276 strict (default): access to resources claimed by ACPI 277 is denied; legacy drivers trying to access reserved 278 resources will fail to bind to device using them. 279 lax: access to resources claimed by ACPI is allowed; 280 legacy drivers trying to access reserved resources 281 will bind successfully but a warning message is logged. 282 no: ACPI OperationRegions are not marked as reserved, 283 no further checks are performed. 284 285 ad1848= [HW,OSS] 286 Format: <io>,<irq>,<dma>,<dma2>,<type> 287 288 add_efi_memmap [EFI; X86] Include EFI memory map in 289 kernel's map of available physical RAM. 290 291 advansys= [HW,SCSI] 292 See header of drivers/scsi/advansys.c. 293 294 advwdt= [HW,WDT] Advantech WDT 295 Format: <iostart>,<iostop> 296 297 aedsp16= [HW,OSS] Audio Excel DSP 16 298 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq> 299 See also header of sound/oss/aedsp16.c. 300 301 agp= [AGP] 302 { off | try_unsupported } 303 off: disable AGP support 304 try_unsupported: try to drive unsupported chipsets 305 (may crash computer or cause data corruption) 306 307 aha152x= [HW,SCSI] 308 See Documentation/scsi/aha152x.txt. 309 310 aha1542= [HW,SCSI] 311 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]] 312 313 aic7xxx= [HW,SCSI] 314 See Documentation/scsi/aic7xxx.txt. 315 316 aic79xx= [HW,SCSI] 317 See Documentation/scsi/aic79xx.txt. 318 319 amd_iommu= [HW,X86-84] 320 Pass parameters to the AMD IOMMU driver in the system. 321 Possible values are: 322 isolate - enable device isolation (each device, as far 323 as possible, will get its own protection 324 domain) [default] 325 share - put every device behind one IOMMU into the 326 same protection domain 327 fullflush - enable flushing of IO/TLB entries when 328 they are unmapped. Otherwise they are 329 flushed before they will be reused, which 330 is a lot of faster 331 332 amd_iommu_size= [HW,X86-64] 333 Define the size of the aperture for the AMD IOMMU 334 driver. Possible values are: 335 '32M', '64M' (default), '128M', '256M', '512M', '1G' 336 337 amijoy.map= [HW,JOY] Amiga joystick support 338 Map of devices attached to JOY0DAT and JOY1DAT 339 Format: <a>,<b> 340 See also Documentation/kernel/input/joystick.txt 341 342 analog.map= [HW,JOY] Analog joystick and gamepad support 343 Specifies type or capabilities of an analog joystick 344 connected to one of 16 gameports 345 Format: <type1>,<type2>,..<type16> 346 347 apc= [HW,SPARC] 348 Power management functions (SPARCstation-4/5 + deriv.) 349 Format: noidle 350 Disable APC CPU standby support. SPARCstation-Fox does 351 not play well with APC CPU idle - disable it if you have 352 APC and your system crashes randomly. 353 354 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller 355 Change the output verbosity whilst booting 356 Format: { quiet (default) | verbose | debug } 357 Change the amount of debugging information output 358 when initialising the APIC and IO-APIC components. 359 360 apm= [APM] Advanced Power Management 361 See header of arch/x86/kernel/apm_32.c. 362 363 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards 364 Format: <io>,<irq>,<nodeID> 365 366 ataflop= [HW,M68k] 367 368 atarimouse= [HW,MOUSE] Atari Mouse 369 370 atascsi= [HW,SCSI] Atari SCSI 371 372 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, 373 EzKey and similar keyboards 374 375 atkbd.reset= [HW] Reset keyboard during initialization 376 377 atkbd.set= [HW] Select keyboard code set 378 Format: <int> (2 = AT (default), 3 = PS/2) 379 380 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar 381 keyboards 382 383 atkbd.softraw= [HW] Choose between synthetic and real raw mode 384 Format: <bool> (0 = real, 1 = synthetic (default)) 385 386 atkbd.softrepeat= [HW] 387 Use software keyboard repeat 388 389 autotest [IA64] 390 391 baycom_epp= [HW,AX25] 392 Format: <io>,<mode> 393 394 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem 395 Format: <io>,<mode> 396 See header of drivers/net/hamradio/baycom_par.c. 397 398 baycom_ser_fdx= [HW,AX25] 399 BayCom Serial Port AX.25 Modem (Full Duplex Mode) 400 Format: <io>,<irq>,<mode>[,<baud>] 401 See header of drivers/net/hamradio/baycom_ser_fdx.c. 402 403 baycom_ser_hdx= [HW,AX25] 404 BayCom Serial Port AX.25 Modem (Half Duplex Mode) 405 Format: <io>,<irq>,<mode> 406 See header of drivers/net/hamradio/baycom_ser_hdx.c. 407 408 boot_delay= Milliseconds to delay each printk during boot. 409 Values larger than 10 seconds (10000) are changed to 410 no delay (0). 411 Format: integer 412 413 bootmem_debug [KNL] Enable bootmem allocator debug messages. 414 415 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) 416 bttv.radio= Most important insmod options are available as 417 kernel args too. 418 bttv.pll= See Documentation/video4linux/bttv/Insmod-options 419 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST 420 421 BusLogic= [HW,SCSI] 422 See drivers/scsi/BusLogic.c, comment before function 423 BusLogic_ParseDriverOptions(). 424 425 c101= [NET] Moxa C101 synchronous serial card 426 427 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. 428 Sometimes CPU hardware bugs make them report the cache 429 size incorrectly. The kernel will attempt work arounds 430 to fix known problems, but for some CPUs it is not 431 possible to determine what the correct size should be. 432 This option provides an override for these situations. 433 434 capability.disable= 435 [SECURITY] Disable capabilities. This would normally 436 be used only if an alternative security model is to be 437 configured. Potentially dangerous and should only be 438 used if you are entirely sure of the consequences. 439 440 ccw_timeout_log [S390] 441 See Documentation/s390/CommonIO for details. 442 443 cgroup_disable= [KNL] Disable a particular controller 444 Format: {name of the controller(s) to disable} 445 {Currently supported controllers - "memory"} 446 447 checkreqprot [SELINUX] Set initial checkreqprot flag value. 448 Format: { "0" | "1" } 449 See security/selinux/Kconfig help text. 450 0 -- check protection applied by kernel (includes 451 any implied execute protection). 452 1 -- check protection requested by application. 453 Default value is set via a kernel config option. 454 Value can be changed at runtime via 455 /selinux/checkreqprot. 456 457 cio_ignore= [S390] 458 See Documentation/s390/CommonIO for details. 459 460 clock= [BUGS=X86-32, HW] gettimeofday clocksource override. 461 [Deprecated] 462 Forces specified clocksource (if available) to be used 463 when calculating gettimeofday(). If specified 464 clocksource is not available, it defaults to PIT. 465 Format: { pit | tsc | cyclone | pmtmr } 466 467 clocksource= [GENERIC_TIME] Override the default clocksource 468 Format: <string> 469 Override the default clocksource and use the clocksource 470 with the name specified. 471 Some clocksource names to choose from, depending on 472 the platform: 473 [all] jiffies (this is the base, fallback clocksource) 474 [ACPI] acpi_pm 475 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, 476 pxa_timer,timer3,32k_counter,timer0_1 477 [AVR32] avr32 478 [X86-32] pit,hpet,tsc,vmi-timer; 479 scx200_hrt on Geode; cyclone on IBM x440 480 [MIPS] MIPS 481 [PARISC] cr16 482 [S390] tod 483 [SH] SuperH 484 [SPARC64] tick 485 [X86-64] hpet,tsc 486 487 clearcpuid=BITNUM [X86] 488 Disable CPUID feature X for the kernel. See 489 arch/x86/include/asm/cpufeature.h for the valid bit 490 numbers. Note the Linux specific bits are not necessarily 491 stable over kernel options, but the vendor specific 492 ones should be. 493 Also note that user programs calling CPUID directly 494 or using the feature without checking anything 495 will still see it. This just prevents it from 496 being used by the kernel or shown in /proc/cpuinfo. 497 Also note the kernel might malfunction if you disable 498 some critical bits. 499 500 code_bytes [X86] How many bytes of object code to print 501 in an oops report. 502 Range: 0 - 8192 503 Default: 64 504 505 com20020= [HW,NET] ARCnet - COM20020 chipset 506 Format: 507 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] 508 509 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) 510 Format: <io>[,<irq>] 511 512 com90xx= [HW,NET] 513 ARCnet - COM90xx chipset (memory-mapped buffers) 514 Format: <io>[,<irq>[,<memstart>]] 515 516 condev= [HW,S390] console device 517 conmode= 518 519 console= [KNL] Output console device and options. 520 521 tty<n> Use the virtual console device <n>. 522 523 ttyS<n>[,options] 524 ttyUSB0[,options] 525 Use the specified serial port. The options are of 526 the form "bbbbpnf", where "bbbb" is the baud rate, 527 "p" is parity ("n", "o", or "e"), "n" is number of 528 bits, and "f" is flow control ("r" for RTS or 529 omit it). Default is "9600n8". 530 531 See Documentation/serial-console.txt for more 532 information. See 533 Documentation/networking/netconsole.txt for an 534 alternative. 535 536 uart[8250],io,<addr>[,options] 537 uart[8250],mmio,<addr>[,options] 538 Start an early, polled-mode console on the 8250/16550 539 UART at the specified I/O port or MMIO address, 540 switching to the matching ttyS device later. The 541 options are the same as for ttyS, above. 542 543 If the device connected to the port is not a TTY but a braille 544 device, prepend "brl," before the device type, for instance 545 console=brl,ttyS0 546 For now, only VisioBraille is supported. 547 548 coredump_filter= 549 [KNL] Change the default value for 550 /proc/<pid>/coredump_filter. 551 See also Documentation/filesystems/proc.txt. 552 553 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver 554 Format: 555 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] 556 557 crashkernel=nn[KMG]@ss[KMG] 558 [KNL] Reserve a chunk of physical memory to 559 hold a kernel to switch to with kexec on panic. 560 561 crashkernel=range1:size1[,range2:size2,...][@offset] 562 [KNL] Same as above, but depends on the memory 563 in the running system. The syntax of range is 564 start-[end] where start and end are both 565 a memory unit (amount[KMG]). See also 566 Documentation/kdump/kdump.txt for a example. 567 568 cs89x0_dma= [HW,NET] 569 Format: <dma> 570 571 cs89x0_media= [HW,NET] 572 Format: { rj45 | aui | bnc } 573 574 dasd= [HW,NET] 575 See header of drivers/s390/block/dasd_devmap.c. 576 577 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port 578 (one device per port) 579 Format: <port#>,<type> 580 See also Documentation/input/joystick-parport.txt 581 582 debug [KNL] Enable kernel debugging (events log level). 583 584 debug_locks_verbose= 585 [KNL] verbose self-tests 586 Format=<0|1> 587 Print debugging info while doing the locking API 588 self-tests. 589 We default to 0 (no extra messages), setting it to 590 1 will print _a lot_ more information - normally 591 only useful to kernel developers. 592 593 debug_objects [KNL] Enable object debugging 594 595 no_debug_objects 596 [KNL] Disable object debugging 597 598 debugpat [X86] Enable PAT debugging 599 600 decnet.addr= [HW,NET] 601 Format: <area>[,<node>] 602 See also Documentation/networking/decnet.txt. 603 604 default_hugepagesz= 605 [same as hugepagesz=] The size of the default 606 HugeTLB page size. This is the size represented by 607 the legacy /proc/ hugepages APIs, used for SHM, and 608 default size when mounting hugetlbfs filesystems. 609 Defaults to the default architecture's huge page size 610 if not specified. 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/serial/digiepca.txt. 621 622 disable_mtrr_cleanup [X86] 623 The kernel tries to adjust MTRR layout from continuous 624 to discrete, to make X server driver able to add WB 625 entry later. This parameter disables that. 626 627 disable_mtrr_trim [X86, Intel and AMD only] 628 By default the kernel will trim any uncacheable 629 memory out of your available memory pool based on 630 MTRR settings. This parameter disables that behavior, 631 possibly causing your machine to run very slowly. 632 633 disable_timer_pin_1 [X86] 634 Disable PIN 1 of APIC timer 635 Can be useful to work around chipset bugs. 636 637 dmasound= [HW,OSS] Sound subsystem buffers 638 639 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, 640 this option disables the debugging code at boot. 641 642 dma_debug_entries=<number> 643 This option allows to tune the number of preallocated 644 entries for DMA-API debugging code. One entry is 645 required per DMA-API allocation. Use this if the 646 DMA-API debugging code disables itself because the 647 architectural default is too low. 648 649 dscc4.setup= [NET] 650 651 dtc3181e= [HW,SCSI] 652 653 dynamic_printk Enables pr_debug()/dev_dbg() calls if 654 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. 655 These can also be switched on/off via 656 <debugfs>/dynamic_printk/modules 657 658 earlycon= [KNL] Output early console device and options. 659 uart[8250],io,<addr>[,options] 660 uart[8250],mmio,<addr>[,options] 661 Start an early, polled-mode console on the 8250/16550 662 UART at the specified I/O port or MMIO address. 663 The options are the same as for ttyS, above. 664 665 earlyprintk= [X86,SH,BLACKFIN] 666 earlyprintk=vga 667 earlyprintk=serial[,ttySn[,baudrate]] 668 earlyprintk=dbgp 669 670 Append ",keep" to not disable it when the real console 671 takes over. 672 673 Only vga or serial or usb debug port at a time. 674 675 Currently only ttyS0 and ttyS1 are supported. 676 677 Interaction with the standard serial driver is not 678 very good. 679 680 The VGA output is eventually overwritten by the real 681 console. 682 683 eata= [HW,SCSI] 684 685 edd= [EDD] 686 Format: {"off" | "on" | "skip[mbr]"} 687 688 eisa_irq_edge= [PARISC,HW] 689 See header of drivers/parisc/eisa.c. 690 691 elanfreq= [X86-32] 692 See comment before function elanfreq_setup() in 693 arch/x86/kernel/cpu/cpufreq/elanfreq.c. 694 695 elevator= [IOSCHED] 696 Format: {"anticipatory" | "cfq" | "deadline" | "noop"} 697 See Documentation/block/as-iosched.txt and 698 Documentation/block/deadline-iosched.txt for details. 699 700 elfcorehdr= [IA64,PPC,SH,X86] 701 Specifies physical address of start of kernel core 702 image elf header. Generally kexec loader will 703 pass this option to capture kernel. 704 See Documentation/kdump/kdump.txt for details. 705 706 enable_mtrr_cleanup [X86] 707 The kernel tries to adjust MTRR layout from continuous 708 to discrete, to make X server driver able to add WB 709 entry later. This parameter enables that. 710 711 enable_timer_pin_1 [X86] 712 Enable PIN 1 of APIC timer 713 Can be useful to work around chipset bugs 714 (in particular on some ATI chipsets). 715 The kernel tries to set a reasonable default. 716 717 enforcing [SELINUX] Set initial enforcing status. 718 Format: {"0" | "1"} 719 See security/selinux/Kconfig help text. 720 0 -- permissive (log only, no denials). 721 1 -- enforcing (deny and log). 722 Default value is 0. 723 Value can be changed at runtime via /selinux/enforce. 724 725 ether= [HW,NET] Ethernet cards parameters 726 This option is obsoleted by the "netdev=" option, which 727 has equivalent usage. See its documentation for details. 728 729 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. 730 Format: <io>[,<irq>] 731 732 failslab= 733 fail_page_alloc= 734 fail_make_request=[KNL] 735 General fault injection mechanism. 736 Format: <interval>,<probability>,<space>,<times> 737 See also /Documentation/fault-injection/. 738 739 fd_mcs= [HW,SCSI] 740 See header of drivers/scsi/fd_mcs.c. 741 742 fdomain= [HW,SCSI] 743 See header of drivers/scsi/fdomain.c. 744 745 floppy= [HW] 746 See Documentation/blockdev/floppy.txt. 747 748 force_pal_cache_flush 749 [IA-64] Avoid check_sal_cache_flush which may hang on 750 buggy SAL_CACHE_FLUSH implementations. Using this 751 parameter will force ia64_sal_cache_flush to call 752 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. 753 754 ftrace=[tracer] 755 [ftrace] will set and start the specified tracer 756 as early as possible in order to facilitate early 757 boot debugging. 758 759 ftrace_dump_on_oops 760 [ftrace] will dump the trace buffers on oops. 761 762 gamecon.map[2|3]= 763 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad 764 support via parallel port (up to 5 devices per port) 765 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> 766 See also Documentation/input/joystick-parport.txt 767 768 gamma= [HW,DRM] 769 770 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART 771 Format: off | on 772 default: on 773 774 gdth= [HW,SCSI] 775 See header of drivers/scsi/gdth.c. 776 777 gpt [EFI] Forces disk with valid GPT signature but 778 invalid Protective MBR to be treated as GPT. 779 780 gvp11= [HW,SCSI] 781 782 hashdist= [KNL,NUMA] Large hashes allocated during boot 783 are distributed across NUMA nodes. Defaults on 784 for 64bit NUMA, off otherwise. 785 Format: 0 | 1 (for off | on) 786 787 hcl= [IA-64] SGI's Hardware Graph compatibility layer 788 789 hd= [EIDE] (E)IDE hard drive subsystem geometry 790 Format: <cyl>,<head>,<sect> 791 792 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact 793 size of <nn>. This works even on boxes that have no 794 highmem otherwise. This also works to reduce highmem 795 size on bigger boxes. 796 797 highres= [KNL] Enable/disable high resolution timer mode. 798 Valid parameters: "on", "off" 799 Default: "on" 800 801 hisax= [HW,ISDN] 802 See Documentation/isdn/README.HiSax. 803 804 hlt [BUGS=ARM,SH] 805 806 hpet= [X86-32,HPET] option to control HPET usage 807 Format: { enable (default) | disable | force | 808 verbose } 809 disable: disable HPET and use PIT instead 810 force: allow force enabled of undocumented chips (ICH4, 811 VIA, nVidia) 812 verbose: show contents of HPET registers during setup 813 814 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. 815 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. 816 On x86-64 and powerpc, this option can be specified 817 multiple times interleaved with hugepages= to reserve 818 huge pages of different sizes. Valid pages sizes on 819 x86-64 are 2M (when the CPU supports "pse") and 1G 820 (when the CPU supports the "pdpe1gb" cpuinfo flag) 821 Note that 1GB pages can only be allocated at boot time 822 using hugepages= and not freed afterwards. 823 824 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) 825 terminal devices. Valid values: 0..8 826 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. 827 If specified, z/VM IUCV HVC accepts connections 828 from listed z/VM user IDs only. 829 830 i2c_bus= [HW] Override the default board specific I2C bus speed 831 or register an additional I2C bus that is not 832 registered from board initialization code. 833 Format: 834 <bus_id>,<clkrate> 835 836 i8042.debug [HW] Toggle i8042 debug mode 837 i8042.direct [HW] Put keyboard port into non-translated mode 838 i8042.dumbkbd [HW] Pretend that controller can only read data from 839 keyboard and cannot control its state 840 (Don't attempt to blink the leds) 841 i8042.noaux [HW] Don't check for auxiliary (== mouse) port 842 i8042.nokbd [HW] Don't check/create keyboard port 843 i8042.noloop [HW] Disable the AUX Loopback command while probing 844 for the AUX port 845 i8042.nomux [HW] Don't check presence of an active multiplexing 846 controller 847 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX 848 controllers 849 i8042.panicblink= 850 [HW] Frequency with which keyboard LEDs should blink 851 when kernel panics (default is 0.5 sec) 852 i8042.reset [HW] Reset the controller during init and cleanup 853 i8042.unlock [HW] Unlock (ignore) the keylock 854 855 i810= [HW,DRM] 856 857 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data 858 indicates that the driver is running on unsupported 859 hardware. 860 i8k.force [HW] Activate i8k driver even if SMM BIOS signature 861 does not match list of supported models. 862 i8k.power_status 863 [HW] Report power status in /proc/i8k 864 (disabled by default) 865 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN 866 capability is set. 867 868 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter 869 See Documentation/mca.txt. 870 871 icn= [HW,ISDN] 872 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] 873 874 ide-core.nodma= [HW] (E)IDE subsystem 875 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc 876 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom 877 .chs .ignore_cable are additional options 878 See Documentation/ide/ide.txt. 879 880 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed 881 See Documentation/ide/ide.txt. 882 883 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem 884 Claim all unknown PCI IDE storage controllers. 885 886 idle= [X86] 887 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait 888 Poll forces a polling idle loop that can slightly 889 improve the performance of waking up a idle CPU, but 890 will use a lot of power and make the system run hot. 891 Not recommended. 892 idle=mwait: On systems which support MONITOR/MWAIT but 893 the kernel chose to not use it because it doesn't save 894 as much power as a normal idle loop, use the 895 MONITOR/MWAIT idle loop anyways. Performance should be 896 the same as idle=poll. 897 idle=halt: Halt is forced to be used for CPU idle. 898 In such case C2/C3 won't be used again. 899 idle=nomwait: Disable mwait for CPU C-states 900 901 ignore_loglevel [KNL] 902 Ignore loglevel setting - this will print /all/ 903 kernel messages to the console. Useful for debugging. 904 905 ihash_entries= [KNL] 906 Set number of hash buckets for inode cache. 907 908 ima_audit= [IMA] 909 Format: { "0" | "1" } 910 0 -- integrity auditing messages. (Default) 911 1 -- enable informational integrity auditing messages. 912 913 ima_hash= [IMA] 914 Formt: { "sha1" | "md5" } 915 default: "sha1" 916 917 in2000= [HW,SCSI] 918 See header of drivers/scsi/in2000.c. 919 920 init= [KNL] 921 Format: <full_path> 922 Run specified binary instead of /sbin/init as init 923 process. 924 925 initcall_debug [KNL] Trace initcalls as they are executed. Useful 926 for working out where the kernel is dying during 927 startup. 928 929 initrd= [BOOT] Specify the location of the initial ramdisk 930 931 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver 932 Format: <irq> 933 934 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option 935 on 936 Enable intel iommu driver. 937 off 938 Disable intel iommu driver. 939 igfx_off [Default Off] 940 By default, gfx is mapped as normal device. If a gfx 941 device has a dedicated DMAR unit, the DMAR unit is 942 bypassed by not enabling DMAR with this option. In 943 this case, gfx device will use physical address for 944 DMA. 945 forcedac [x86_64] 946 With this option iommu will not optimize to look 947 for io virtual address below 32 bit forcing dual 948 address cycle on pci bus for cards supporting greater 949 than 32 bit addressing. The default is to look 950 for translation below 32 bit and if not available 951 then look in the higher range. 952 strict [Default Off] 953 With this option on every unmap_single operation will 954 result in a hardware IOTLB flush operation as opposed 955 to batching them for performance. 956 957 inttest= [IA64] 958 959 iomem= Disable strict checking of access to MMIO memory 960 strict regions from userspace. 961 relaxed 962 963 iommu= [x86] 964 off 965 force 966 noforce 967 biomerge 968 panic 969 nopanic 970 merge 971 nomerge 972 forcesac 973 soft 974 975 io7= [HW] IO7 for Marvel based alpha systems 976 See comment before marvel_specify_io7 in 977 arch/alpha/kernel/core_marvel.c. 978 979 io_delay= [X86] I/O delay method 980 0x80 981 Standard port 0x80 based delay 982 0xed 983 Alternate port 0xed based delay (needed on some systems) 984 udelay 985 Simple two microseconds delay 986 none 987 No delay 988 989 ip= [IP_PNP] 990 See Documentation/filesystems/nfsroot.txt. 991 992 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards 993 See comment before ip2_setup() in 994 drivers/char/ip2/ip2base.c. 995 996 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller 997 See header of drivers/scsi/ips.c. 998 999 irqfixup [HW] 1000 When an interrupt is not handled search all handlers
1001 for it. Intended to get systems with badly broken 1002 firmware running. 1003 1004 irqpoll [HW] 1005 When an interrupt is not handled search all handlers 1006 for it. Also check all handlers each timer 1007 interrupt. Intended to get systems with badly broken 1008 firmware running. 1009 1010 isapnp= [ISAPNP] 1011 Format: <RDP>,<reset>,<pci_scan>,<verbosity> 1012 1013 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. 1014 Format: 1015 <cpu number>,...,<cpu number> 1016 or 1017 <cpu number>-<cpu number> 1018 (must be a positive range in ascending order) 1019 or a mixture 1020 <cpu number>,...,<cpu number>-<cpu number> 1021 1022 This option can be used to specify one or more CPUs 1023 to isolate from the general SMP balancing and scheduling 1024 algorithms. You can move a process onto or off an 1025 "isolated" CPU via the CPU affinity syscalls or cpuset. 1026 <cpu number> begins at 0 and the maximum value is 1027 "number of CPUs in system - 1". 1028 1029 This option is the preferred way to isolate CPUs. The 1030 alternative -- manually setting the CPU mask of all 1031 tasks in the system -- can cause problems and 1032 suboptimal load balancer performance. 1033 1034 iucv= [HW,NET] 1035 1036 js= [HW,JOY] Analog joystick 1037 See Documentation/input/joystick.txt. 1038 1039 keepinitrd [HW,ARM] 1040 1041 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter 1042 specifies the amount of memory usable by the kernel 1043 for non-movable allocations. The requested amount is 1044 spread evenly throughout all nodes in the system. The 1045 remaining memory in each node is used for Movable 1046 pages. In the event, a node is too small to have both 1047 kernelcore and Movable pages, kernelcore pages will 1048 take priority and other nodes will have a larger number 1049 of kernelcore pages. The Movable zone is used for the 1050 allocation of pages that may be reclaimed or moved 1051 by the page migration subsystem. This means that 1052 HugeTLB pages may not be allocated from this zone. 1053 Note that allocations like PTEs-from-HighMem still 1054 use the HighMem zone if it exists, and the Normal 1055 zone if it does not. 1056 1057 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no } 1058 Controls whether kmemtrace is enabled 1059 at boot-time. 1060 1061 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of 1062 subbufs kmemtrace's relay channel has. Set this 1063 higher than default (KMEMTRACE_N_SUBBUFS in code) if 1064 you experience buffer overruns. 1065 1066 kgdboc= [HW] kgdb over consoles. 1067 Requires a tty driver that supports console polling. 1068 (only serial suported for now) 1069 Format: <serial_device>[,baud] 1070 1071 kmac= [MIPS] korina ethernet MAC address. 1072 Configure the RouterBoard 532 series on-chip 1073 Ethernet adapter MAC address. 1074 1075 kstack=N [X86] Print N words from the kernel stack 1076 in oops dumps. 1077 1078 l2cr= [PPC] 1079 1080 l3cr= [PPC] 1081 1082 lapic [X86-32,APIC] Enable the local APIC even if BIOS 1083 disabled it. 1084 1085 lapic_timer_c2_ok [X86,APIC] trust the local apic timer 1086 in C2 power state. 1087 1088 libata.dma= [LIBATA] DMA control 1089 libata.dma=0 Disable all PATA and SATA DMA 1090 libata.dma=1 PATA and SATA Disk DMA only 1091 libata.dma=2 ATAPI (CDROM) DMA only 1092 libata.dma=4 Compact Flash DMA only 1093 Combinations also work, so libata.dma=3 enables DMA 1094 for disks and CDROMs, but not CFs. 1095 1096 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume 1097 when set. 1098 Format: <int> 1099 1100 libata.force= [LIBATA] Force configurations. The format is comma 1101 separated list of "[ID:]VAL" where ID is 1102 PORT[:DEVICE]. PORT and DEVICE are decimal numbers 1103 matching port, link or device. Basically, it matches 1104 the ATA ID string printed on console by libata. If 1105 the whole ID part is omitted, the last PORT and DEVICE 1106 values are used. If ID hasn't been specified yet, the 1107 configuration applies to all ports, links and devices. 1108 1109 If only DEVICE is omitted, the parameter applies to 1110 the port and all links and devices behind it. DEVICE 1111 number of 0 either selects the first device or the 1112 first fan-out link behind PMP device. It does not 1113 select the host link. DEVICE number of 15 selects the 1114 host link and device attached to it. 1115 1116 The VAL specifies the configuration to force. As long 1117 as there's no ambiguity shortcut notation is allowed. 1118 For example, both 1.5 and 1.5G would work for 1.5Gbps. 1119 The following configurations can be forced. 1120 1121 * Cable type: 40c, 80c, short40c, unk, ign or sata. 1122 Any ID with matching PORT is used. 1123 1124 * SATA link speed limit: 1.5Gbps or 3.0Gbps. 1125 1126 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. 1127 udma[/][16,25,33,44,66,100,133] notation is also 1128 allowed. 1129 1130 * [no]ncq: Turn on or off NCQ. 1131 1132 * nohrst, nosrst, norst: suppress hard, soft 1133 and both resets. 1134 1135 If there are multiple matching configurations changing 1136 the same attribute, the last one is used. 1137 1138 lmb=debug [KNL] Enable lmb debug messages. 1139 1140 load_ramdisk= [RAM] List of ramdisks to load from floppy 1141 See Documentation/blockdev/ramdisk.txt. 1142 1143 lockd.nlm_grace_period=P [NFS] Assign grace period. 1144 Format: <integer> 1145 1146 lockd.nlm_tcpport=N [NFS] Assign TCP port. 1147 Format: <integer> 1148 1149 lockd.nlm_timeout=T [NFS] Assign timeout value. 1150 Format: <integer> 1151 1152 lockd.nlm_udpport=M [NFS] Assign UDP port. 1153 Format: <integer> 1154 1155 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver 1156 Format: <irq> 1157 1158 loglevel= All Kernel Messages with a loglevel smaller than the 1159 console loglevel will be printed to the console. It can 1160 also be changed with klogd or other programs. The 1161 loglevels are defined as follows: 1162 1163 0 (KERN_EMERG) system is unusable 1164 1 (KERN_ALERT) action must be taken immediately 1165 2 (KERN_CRIT) critical conditions 1166 3 (KERN_ERR) error conditions 1167 4 (KERN_WARNING) warning conditions 1168 5 (KERN_NOTICE) normal but significant condition 1169 6 (KERN_INFO) informational 1170 7 (KERN_DEBUG) debug-level messages 1171 1172 log_buf_len=n Sets the size of the printk ring buffer, in bytes. 1173 Format: { n | nk | nM } 1174 n must be a power of two. The default size 1175 is set in the kernel config file. 1176 1177 logo.nologo [FB] Disables display of the built-in Linux logo. 1178 This may be used to provide more screen space for 1179 kernel log messages and is useful when debugging 1180 kernel boot problems. 1181 1182 lp=0 [LP] Specify parallel ports to use, e.g, 1183 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses 1184 lp=reset first parallel port). 'lp=0' disables the 1185 lp=auto printer driver. 'lp=reset' (which can be 1186 specified in addition to the ports) causes 1187 attached printers to be reset. Using 1188 lp=port1,port2,... specifies the parallel ports 1189 to associate lp devices with, starting with 1190 lp0. A port specification may be 'none' to skip 1191 that lp device, or a parport name such as 1192 'parport0'. Specifying 'lp=auto' instead of a 1193 port specification list means that device IDs 1194 from each port should be examined, to see if 1195 an IEEE 1284-compliant printer is attached; if 1196 so, the driver will manage that printer. 1197 See also header of drivers/char/lp.c. 1198 1199 lpj=n [KNL] 1200 Sets loops_per_jiffy to given constant, thus avoiding 1201 time-consuming boot-time autodetection (up to 250 ms per 1202 CPU). 0 enables autodetection (default). To determine 1203 the correct value for your kernel, boot with normal 1204 autodetection and see what value is printed. Note that 1205 on SMP systems the preset will be applied to all CPUs, 1206 which is likely to cause problems if your CPUs need 1207 significantly divergent settings. An incorrect value 1208 will cause delays in the kernel to be wrong, leading to 1209 unpredictable I/O errors and other breakage. Although 1210 unlikely, in the extreme case this might damage your 1211 hardware. 1212 1213 ltpc= [NET] 1214 Format: <io>,<irq>,<dma> 1215 1216 mac5380= [HW,SCSI] Format: 1217 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> 1218 1219 machvec= [IA64] Force the use of a particular machine-vector 1220 (machvec) in a generic kernel. 1221 Example: machvec=hpzx1_swiotlb 1222 1223 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater 1224 than or equal to this physical address is ignored. 1225 1226 maxcpus= [SMP] Maximum number of processors that an SMP kernel 1227 should make use of. maxcpus=n : n >= 0 limits the 1228 kernel to using 'n' processors. n=0 is a special case, 1229 it is equivalent to "nosmp", which also disables 1230 the IO APIC. 1231 1232 max_loop= [LOOP] Maximum number of loopback devices that can 1233 be mounted 1234 Format: <1-256> 1235 1236 max_luns= [SCSI] Maximum number of LUNs to probe. 1237 Should be between 1 and 2^32-1. 1238 1239 max_report_luns= 1240 [SCSI] Maximum number of LUNs received. 1241 Should be between 1 and 16384. 1242 1243 mcatest= [IA-64] 1244 1245 mce [X86-32] Machine Check Exception 1246 1247 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt 1248 1249 md= [HW] RAID subsystems devices and level 1250 See Documentation/md.txt. 1251 1252 mdacon= [MDA] 1253 Format: <first>,<last> 1254 Specifies range of consoles to be captured by the MDA. 1255 1256 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory 1257 Amount of memory to be used when the kernel is not able 1258 to see the whole system memory or for test. 1259 [X86-32] Use together with memmap= to avoid physical 1260 address space collisions. Without memmap= PCI devices 1261 could be placed at addresses belonging to unused RAM. 1262 1263 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel 1264 memory. 1265 1266 memchunk=nn[KMG] 1267 [KNL,SH] Allow user to override the default size for 1268 per-device physically contiguous DMA buffers. 1269 1270 memmap=exactmap [KNL,X86] Enable setting of an exact 1271 E820 memory map, as specified by the user. 1272 Such memmap=exactmap lines can be constructed based on 1273 BIOS output or other requirements. See the memmap=nn@ss 1274 option description. 1275 1276 memmap=nn[KMG]@ss[KMG] 1277 [KNL] Force usage of a specific region of memory 1278 Region of memory to be used, from ss to ss+nn. 1279 1280 memmap=nn[KMG]#ss[KMG] 1281 [KNL,ACPI] Mark specific memory as ACPI data. 1282 Region of memory to be used, from ss to ss+nn. 1283 1284 memmap=nn[KMG]$ss[KMG] 1285 [KNL,ACPI] Mark specific memory as reserved. 1286 Region of memory to be used, from ss to ss+nn. 1287 Example: Exclude memory from 0x18690000-0x1869ffff 1288 memmap=64K$0x18690000 1289 or 1290 memmap=0x10000$0x18690000 1291 1292 memory_corruption_check=0/1 [X86] 1293 Some BIOSes seem to corrupt the first 64k of 1294 memory when doing things like suspend/resume. 1295 Setting this option will scan the memory 1296 looking for corruption. Enabling this will 1297 both detect corruption and prevent the kernel 1298 from using the memory being corrupted. 1299 However, its intended as a diagnostic tool; if 1300 repeatable BIOS-originated corruption always 1301 affects the same memory, you can use memmap= 1302 to prevent the kernel from using that memory. 1303 1304 memory_corruption_check_size=size [X86] 1305 By default it checks for corruption in the low 1306 64k, making this memory unavailable for normal 1307 use. Use this parameter to scan for 1308 corruption in more or less memory. 1309 1310 memory_corruption_check_period=seconds [X86] 1311 By default it checks for corruption every 60 1312 seconds. Use this parameter to check at some 1313 other rate. 0 disables periodic checking. 1314 1315 memtest= [KNL,X86] Enable memtest 1316 Format: <integer> 1317 default : 0 <disable> 1318 Specifies the number of memtest passes to be 1319 performed. Each pass selects another test 1320 pattern from a given set of patterns. Memtest 1321 fills the memory with this pattern, validates 1322 memory contents and reserves bad memory 1323 regions that are detected. 1324 1325 meye.*= [HW] Set MotionEye Camera parameters 1326 See Documentation/video4linux/meye.txt. 1327 1328 mfgpt_irq= [IA-32] Specify the IRQ to use for the 1329 Multi-Function General Purpose Timers on AMD Geode 1330 platforms. 1331 1332 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when 1333 the BIOS has incorrectly applied a workaround. TinyBIOS 1334 version 0.98 is known to be affected, 0.99 fixes the 1335 problem by letting the user disable the workaround. 1336 1337 mga= [HW,DRM] 1338 1339 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this 1340 physical address is ignored. 1341 1342 mminit_loglevel= 1343 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this 1344 parameter allows control of the logging verbosity for 1345 the additional memory initialisation checks. A value 1346 of 0 disables mminit logging and a level of 4 will 1347 log everything. Information is printed at KERN_DEBUG 1348 so loglevel=8 may also need to be specified. 1349 1350 mousedev.tap_time= 1351 [MOUSE] Maximum time between finger touching and 1352 leaving touchpad surface for touch to be considered 1353 a tap and be reported as a left button click (for 1354 touchpads working in absolute mode only). 1355 Format: <msecs> 1356 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices 1357 reporting absolute coordinates, such as tablets 1358 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices 1359 reporting absolute coordinates, such as tablets 1360 1361 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter 1362 is similar to kernelcore except it specifies the 1363 amount of memory used for migratable allocations. 1364 If both kernelcore and movablecore is specified, 1365 then kernelcore will be at *least* the specified 1366 value but may be more. If movablecore on its own 1367 is specified, the administrator must be careful 1368 that the amount of memory usable for all allocations 1369 is not too small. 1370 1371 mpu401= [HW,OSS] 1372 Format: <io>,<irq> 1373 1374 MTD_Partition= [MTD] 1375 Format: <name>,<region-number>,<size>,<offset> 1376 1377 MTD_Region= [MTD] Format: 1378 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] 1379 1380 mtdparts= [MTD] 1381 See drivers/mtd/cmdlinepart.c. 1382 1383 mtdset= [ARM] 1384 ARM/S3C2412 JIVE boot control 1385 1386 See arch/arm/mach-s3c2412/mach-jive.c 1387 1388 mtouchusb.raw_coordinates= 1389 [HW] Make the MicroTouch USB driver use raw coordinates 1390 ('y', default) or cooked coordinates ('n') 1391 1392 mtrr_chunk_size=nn[KMG] [X86] 1393 used for mtrr cleanup. It is largest continous chunk 1394 that could hold holes aka. UC entries. 1395 1396 mtrr_gran_size=nn[KMG] [X86] 1397 Used for mtrr cleanup. It is granularity of mtrr block. 1398 Default is 1. 1399 Large value could prevent small alignment from 1400 using up MTRRs. 1401 1402 mtrr_spare_reg_nr=n [X86] 1403 Format: <integer> 1404 Range: 0,7 : spare reg number 1405 Default : 1 1406 Used for mtrr cleanup. It is spare mtrr entries number. 1407 Set to 2 or more if your graphical card needs more. 1408 1409 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card 1410 1411 NCR_D700= [HW,SCSI] 1412 See header of drivers/scsi/NCR_D700.c. 1413 1414 ncr5380= [HW,SCSI] 1415 1416 ncr53c400= [HW,SCSI] 1417 1418 ncr53c400a= [HW,SCSI] 1419 1420 ncr53c406a= [HW,SCSI] 1421 1422 ncr53c8xx= [HW,SCSI] 1423 1424 netdev= [NET] Network devices parameters 1425 Format: <irq>,<io>,<mem_start>,<mem_end>,<name> 1426 Note that mem_start is often overloaded to mean 1427 something different and driver-specific. 1428 This usage is only documented in each driver source 1429 file if at all. 1430 1431 nf_conntrack.acct= 1432 [NETFILTER] Enable connection tracking flow accounting 1433 0 to disable accounting 1434 1 to enable accounting 1435 Default value depends on CONFIG_NF_CT_ACCT that is 1436 going to be removed in 2.6.29. 1437 1438 nfsaddrs= [NFS] 1439 See Documentation/filesystems/nfsroot.txt. 1440 1441 nfsroot= [NFS] nfs root filesystem for disk-less boxes. 1442 See Documentation/filesystems/nfsroot.txt. 1443 1444 nfs.callback_tcpport= 1445 [NFS] set the TCP port on which the NFSv4 callback 1446 channel should listen. 1447 1448 nfs.idmap_cache_timeout= 1449 [NFS] set the maximum lifetime for idmapper cache 1450 entries. 1451 1452 nfs.enable_ino64= 1453 [NFS] enable 64-bit inode numbers. 1454 If zero, the NFS client will fake up a 32-bit inode 1455 number for the readdir() and stat() syscalls instead 1456 of returning the full 64-bit number. 1457 The default is to return 64-bit inode numbers. 1458 1459 nmi_debug= [KNL,AVR32] Specify one or more actions to take 1460 when a NMI is triggered. 1461 Format: [state][,regs][,debounce][,die] 1462 1463 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels 1464 Format: [panic,][num] 1465 Valid num: 0,1,2 1466 0 - turn nmi_watchdog off 1467 1 - use the IO-APIC timer for the NMI watchdog 1468 2 - use the local APIC for the NMI watchdog using 1469 a performance counter. Note: This will use one 1470 performance counter and the local APIC's performance 1471 vector. 1472 When panic is specified, panic when an NMI watchdog 1473 timeout occurs. 1474 This is useful when you use a panic=... timeout and 1475 need the box quickly up again. 1476 Instead of 1 and 2 it is possible to use the following 1477 symbolic names: lapic and ioapic 1478 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic 1479 1480 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths 1481 emulation library even if a 387 maths coprocessor 1482 is present. 1483 1484 no_console_suspend 1485 [HW] Never suspend the console 1486 Disable suspending of consoles during suspend and 1487 hibernate operations. Once disabled, debugging 1488 messages can reach various consoles while the rest 1489 of the system is being put to sleep (ie, while 1490 debugging driver suspend/resume hooks). This may 1491 not work reliably with all consoles, but is known 1492 to work with serial and VGA consoles. 1493 1494 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien 1495 caches in the slab allocator. Saves per-node memory, 1496 but will impact performance. 1497 1498 noalign [KNL,ARM] 1499 1500 noapic [SMP,APIC] Tells the kernel to not make use of any 1501 IOAPICs that may be present in the system. 1502 1503 nobats [PPC] Do not use BATs for mapping kernel lowmem 1504 on "Classic" PPC cores. 1505 1506 nocache [ARM] 1507 1508 noclflush [BUGS=X86] Don't use the CLFLUSH instruction 1509 1510 nodelayacct [KNL] Disable per-task delay accounting 1511 1512 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. 1513 1514 nodsp [SH] Disable hardware DSP at boot time. 1515 1516 noefi [X86] Disable EFI runtime services support. 1517 1518 noexec [IA-64] 1519 1520 noexec [X86] 1521 On X86-32 available only on PAE configured kernels. 1522 noexec=on: enable non-executable mappings (default) 1523 noexec=off: disable non-executable mappings 1524 1525 noexec32 [X86-64] 1526 This affects only 32-bit executables. 1527 noexec32=on: enable non-executable mappings (default) 1528 read doesn't imply executable mappings 1529 noexec32=off: disable non-executable mappings 1530 read implies executable mappings 1531 1532 nofpu [SH] Disable hardware FPU at boot time. 1533 1534 nofxsr [BUGS=X86-32] Disables x86 floating point extended 1535 register save and restore. The kernel will only save 1536 legacy floating-point registers on task switch. 1537 1538 noxsave [BUGS=X86] Disables x86 extended register state save 1539 and restore using xsave. The kernel will fallback to 1540 enabling legacy floating-point and sse state. 1541 1542 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or 1543 wfi(ARM) instruction doesn't work correctly and not to 1544 use it. This is also useful when using JTAG debugger. 1545 1546 no-hlt [BUGS=X86-32] Tells the kernel that the hlt 1547 instruction doesn't work correctly and not to 1548 use it. 1549 1550 no_file_caps Tells the kernel not to honor file capabilities. The 1551 only way then for a file to be executed with privilege 1552 is to be setuid root or executed by root. 1553 1554 nohalt [IA-64] Tells the kernel not to use the power saving 1555 function PAL_HALT_LIGHT when idle. This increases 1556 power-consumption. On the positive side, it reduces 1557 interrupt wake-up latency, which may improve performance 1558 in certain environments such as networked servers or 1559 real-time systems. 1560 1561 nohz= [KNL] Boottime enable/disable dynamic ticks 1562 Valid arguments: on, off 1563 Default: on 1564 1565 noiotrap [SH] Disables trapped I/O port accesses. 1566 1567 noirqdebug [X86-32] Disables the code which attempts to detect and 1568 disable unhandled interrupt sources. 1569 1570 no_timer_check [X86,APIC] Disables the code which tests for 1571 broken timer IRQ sources. 1572 1573 noisapnp [ISAPNP] Disables ISA PnP code. 1574 1575 noinitrd [RAM] Tells the kernel not to load any configured 1576 initial RAM disk. 1577 1578 nointroute [IA-64] 1579 1580 nojitter [IA64] Disables jitter checking for ITC timers. 1581 1582 nolapic [X86-32,APIC] Do not enable or use the local APIC. 1583 1584 nolapic_timer [X86-32,APIC] Do not use the local APIC timer. 1585 1586 noltlbs [PPC] Do not use large page/tlb entries for kernel 1587 lowmem mapping on PPC40x. 1588 1589 nomca [IA-64] Disable machine check abort handling 1590 1591 nomce [X86-32] Machine Check Exception 1592 1593 nomfgpt [X86-32] Disable Multi-Function General Purpose 1594 Timer usage (for AMD Geode machines). 1595 1596 norandmaps Don't use address space randomization. Equivalent to 1597 echo 0 > /proc/sys/kernel/randomize_va_space 1598 1599 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops 1600 1601 noreplace-smp [X86-32,SMP] Don't replace SMP instructions 1602 with UP alternatives 1603 1604 noresidual [PPC] Don't use residual data on PReP machines. 1605 1606 noresume [SWSUSP] Disables resume and restores original swap 1607 space. 1608 1609 no-scroll [VGA] Disables scrollback. 1610 This is required for the Braillex ib80-piezo Braille 1611 reader made by F.H. Papenmeier (Germany). 1612 1613 nosbagart [IA-64] 1614 1615 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. 1616 1617 nosmp [SMP] Tells an SMP kernel to act as a UP kernel, 1618 and disable the IO APIC. legacy for "maxcpus=0". 1619 1620 nosoftlockup [KNL] Disable the soft-lockup detector. 1621 1622 noswapaccount [KNL] Disable accounting of swap in memory resource 1623 controller. (See Documentation/cgroups/memory.txt) 1624 1625 nosync [HW,M68K] Disables sync negotiation for all devices. 1626 1627 notsc [BUGS=X86-32] Disable Time Stamp Counter 1628 1629 nousb [USB] Disable the USB subsystem 1630 1631 nowb [ARM] 1632 1633 nox2apic [X86-64,APIC] Do not enable x2APIC mode. 1634 1635 nptcg= [IA64] Override max number of concurrent global TLB 1636 purges which is reported from either PAL_VM_SUMMARY or 1637 SAL PALO. 1638 1639 nr_uarts= [SERIAL] maximum number of UARTs to be registered. 1640 1641 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 1642 one of ['zone', 'node', 'default'] can be specified 1643 This can be set from sysctl after boot. 1644 See Documentation/sysctl/vm.txt for details. 1645 1646 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. 1647 See Documentation/debugging-via-ohci1394.txt for more 1648 info. 1649 1650 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands 1651 Rather than timing out after 20 ms if an EC 1652 command is not properly ACKed, override the length 1653 of the timeout. We have interrupts disabled while 1654 waiting for the ACK, so if this is set too high 1655 interrupts *may* be lost! 1656 1657 opl3= [HW,OSS] 1658 Format: <io> 1659 1660 oprofile.timer= [HW] 1661 Use timer interrupt instead of performance counters 1662 1663 osst= [HW,SCSI] SCSI Tape Driver 1664 Format: <buffer_size>,<write_threshold> 1665 See also Documentation/scsi/st.txt. 1666 1667 panic= [KNL] Kernel behaviour on panic 1668 Format: <timeout> 1669 1670 parkbd.port= [HW] Parallel port number the keyboard adapter is 1671 connected to, default is 0. 1672 Format: <parport#> 1673 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, 1674 0 for XT, 1 for AT (default is AT). 1675 Format: <mode> 1676 1677 parport= [HW,PPT] Specify parallel ports. 0 disables. 1678 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } 1679 Use 'auto' to force the driver to use any 1680 IRQ/DMA settings detected (the default is to 1681 ignore detected IRQ/DMA settings because of 1682 possible conflicts). You can specify the base 1683 address, IRQ, and DMA settings; IRQ and DMA 1684 should be numbers, or 'auto' (for using detected 1685 settings on that particular port), or 'nofifo' 1686 (to avoid using a FIFO even if it is detected). 1687 Parallel ports are assigned in the order they 1688 are specified on the command line, starting 1689 with parport0. 1690 1691 parport_init_mode= [HW,PPT] 1692 Configure VIA parallel port to operate in 1693 a specific mode. This is necessary on Pegasos 1694 computer where firmware has no options for setting 1695 up parallel port mode and sets it to spp. 1696 Currently this function knows 686a and 8231 chips. 1697 Format: [spp|ps2|epp|ecp|ecpepp] 1698 1699 pas2= [HW,OSS] Format: 1700 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16> 1701 1702 pas16= [HW,SCSI] 1703 See header of drivers/scsi/pas16.c. 1704 1705 pause_on_oops= 1706 Halt all CPUs after the first oops has been printed for 1707 the specified number of seconds. This is to be used if 1708 your oopses keep scrolling off the screen. 1709 1710 pcbit= [HW,ISDN] 1711 1712 pcd. [PARIDE] 1713 See header of drivers/block/paride/pcd.c. 1714 See also Documentation/blockdev/paride.txt. 1715 1716 pci=option[,option...] [PCI] various PCI subsystem options: 1717 earlydump [X86] dump PCI config space before the kernel 1718 changes anything 1719 off [X86] don't probe for the PCI bus 1720 bios [X86-32] force use of PCI BIOS, don't access 1721 the hardware directly. Use this if your machine 1722 has a non-standard PCI host bridge. 1723 nobios [X86-32] disallow use of PCI BIOS, only direct 1724 hardware access methods are allowed. Use this 1725 if you experience crashes upon bootup and you 1726 suspect they are caused by the BIOS. 1727 conf1 [X86] Force use of PCI Configuration 1728 Mechanism 1. 1729 conf2 [X86] Force use of PCI Configuration 1730 Mechanism 2. 1731 noaer [PCIE] If the PCIEAER kernel config parameter is 1732 enabled, this kernel boot option can be used to 1733 disable the use of PCIE advanced error reporting. 1734 nodomains [PCI] Disable support for multiple PCI 1735 root domains (aka PCI segments, in ACPI-speak). 1736 nommconf [X86] Disable use of MMCONFIG for PCI 1737 Configuration 1738 nomsi [MSI] If the PCI_MSI kernel config parameter is 1739 enabled, this kernel boot option can be used to 1740 disable the use of MSI interrupts system-wide. 1741 noioapicquirk [APIC] Disable all boot interrupt quirks. 1742 Safety option to keep boot IRQs enabled. This 1743 should never be necessary. 1744 ioapicreroute [APIC] Enable rerouting of boot IRQs to the 1745 primary IO-APIC for bridges that cannot disable 1746 boot IRQs. This fixes a source of spurious IRQs 1747 when the system masks IRQs. 1748 noioapicreroute [APIC] Disable workaround that uses the 1749 boot IRQ equivalent of an IRQ that connects to 1750 a chipset where boot IRQs cannot be disabled. 1751 The opposite of ioapicreroute. 1752 biosirq [X86-32] Use PCI BIOS calls to get the interrupt 1753 routing table. These calls are known to be buggy 1754 on several machines and they hang the machine 1755 when used, but on other computers it's the only 1756 way to get the interrupt routing table. Try 1757 this option if the kernel is unable to allocate 1758 IRQs or discover secondary PCI buses on your 1759 motherboard. 1760 rom [X86] Assign address space to expansion ROMs. 1761 Use with caution as certain devices share 1762 address decoders between ROMs and other 1763 resources. 1764 norom [X86] Do not assign address space to 1765 expansion ROMs that do not already have 1766 BIOS assigned address ranges. 1767 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be 1768 assigned automatically to PCI devices. You can 1769 make the kernel exclude IRQs of your ISA cards 1770 this way. 1771 pirqaddr=0xAAAAA [X86] Specify the physical address 1772 of the PIRQ table (normally generated 1773 by the BIOS) if it is outside the 1774 F0000h-100000h range. 1775 lastbus=N [X86] Scan all buses thru bus #N. Can be 1776 useful if the kernel is unable to find your 1777 secondary buses and you want to tell it 1778 explicitly which ones they are. 1779 assign-busses [X86] Always assign all PCI bus 1780 numbers ourselves, overriding 1781 whatever the firmware may have done. 1782 usepirqmask [X86] Honor the possible IRQ mask stored 1783 in the BIOS $PIR table. This is needed on 1784 some systems with broken BIOSes, notably 1785 some HP Pavilion N5400 and Omnibook XE3 1786 notebooks. This will have no effect if ACPI 1787 IRQ routing is enabled. 1788 noacpi [X86] Do not use ACPI for IRQ routing 1789 or for PCI scanning. 1790 use_crs [X86] Use _CRS for PCI resource 1791 allocation. 1792 routeirq Do IRQ routing for all PCI devices. 1793 This is normally done in pci_enable_device(), 1794 so this option is a temporary workaround 1795 for broken drivers that don't call it. 1796 skip_isa_align [X86] do not align io start addr, so can 1797 handle more pci cards 1798 firmware [ARM] Do not re-enumerate the bus but instead 1799 just use the configuration from the 1800 bootloader. This is currently used on 1801 IXP2000 systems where the bus has to be 1802 configured a certain way for adjunct CPUs. 1803 noearly [X86] Don't do any early type 1 scanning. 1804 This might help on some broken boards which 1805 machine check when some devices' config space 1806 is read. But various workarounds are disabled 1807 and some IOMMU drivers will not work. 1808 bfsort Sort PCI devices into breadth-first order. 1809 This sorting is done to get a device 1810 order compatible with older (<= 2.4) kernels. 1811 nobfsort Don't sort PCI devices into breadth-first order. 1812 cbiosize=nn[KMG] The fixed amount of bus space which is 1813 reserved for the CardBus bridge's IO window. 1814 The default value is 256 bytes. 1815 cbmemsize=nn[KMG] The fixed amount of bus space which is 1816 reserved for the CardBus bridge's memory 1817 window. The default value is 64 megabytes. 1818 resource_alignment= 1819 Format: 1820 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] 1821 Specifies alignment and device to reassign 1822 aligned memory resources. 1823 If <order of align> is not specified, 1824 PAGE_SIZE is used as alignment. 1825 PCI-PCI bridge can be specified, if resource 1826 windows need to be expanded. 1827 1828 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power 1829 Management. 1830 off Disable ASPM. 1831 force Enable ASPM even on devices that claim not to support it. 1832 WARNING: Forcing ASPM on may cause system lockups. 1833 1834 pcmv= [HW,PCMCIA] BadgePAD 4 1835 1836 pd. [PARIDE] 1837 See Documentation/blockdev/paride.txt. 1838 1839 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at 1840 boot time. 1841 Format: { 0 | 1 } 1842 See arch/parisc/kernel/pdc_chassis.c 1843 1844 pf. [PARIDE] 1845 See Documentation/blockdev/paride.txt. 1846 1847 pg. [PARIDE] 1848 See Documentation/blockdev/paride.txt. 1849 1850 pirq= [SMP,APIC] Manual mp-table setup 1851 See Documentation/x86/i386/IO-APIC.txt. 1852 1853 plip= [PPT,NET] Parallel port network link 1854 Format: { parport<nr> | timid | 0 } 1855 See also Documentation/parport.txt. 1856 1857 pmtmr= [X86] Manual setup of pmtmr I/O Port. 1858 Override pmtimer IOPort with a hex value. 1859 e.g. pmtmr=0x508 1860 1861 pnp.debug [PNP] 1862 Enable PNP debug messages. This depends on the 1863 CONFIG_PNP_DEBUG_MESSAGES option. 1864 1865 pnpacpi= [ACPI] 1866 { off } 1867 1868 pnpbios= [ISAPNP] 1869 { on | off | curr | res | no-curr | no-res } 1870 1871 pnp_reserve_irq= 1872 [ISAPNP] Exclude IRQs for the autoconfiguration 1873 1874 pnp_reserve_dma= 1875 [ISAPNP] Exclude DMAs for the autoconfiguration 1876 1877 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration 1878 Ranges are in pairs (I/O port base and size). 1879 1880 pnp_reserve_mem= 1881 [ISAPNP] Exclude memory regions for the 1882 autoconfiguration. 1883 Ranges are in pairs (memory base and size). 1884 1885 ports= [IP_VS_FTP] IPVS ftp helper module 1886 Default is 21. 1887 Up to 8 (IP_VS_APP_MAX_PORTS) ports 1888 may be specified. 1889 Format: <port>,<port>.... 1890 1891 print-fatal-signals= 1892 [KNL] debug: print fatal signals 1893 print-fatal-signals=1: print segfault info to 1894 the kernel console. 1895 default: off. 1896 1897 printk.time= Show timing data prefixed to each printk message line 1898 Format: <bool> (1/Y/y=enable, 0/N/n=disable) 1899 1900 processor.max_cstate= [HW,ACPI] 1901 Limit processor to maximum C-state 1902 max_cstate=9 overrides any DMI blacklist limit. 1903 1904 processor.nocst [HW,ACPI] 1905 Ignore the _CST method to determine C-states, 1906 instead using the legacy FADT method 1907 1908 profile= [KNL] Enable kernel profiling via /proc/profile 1909 Format: [schedule,]<number> 1910 Param: "schedule" - profile schedule points. 1911 Param: <number> - step/bucket size as a power of 2 for 1912 statistical time based profiling. 1913 Param: "sleep" - profile D-state sleeping (millisecs). 1914 Requires CONFIG_SCHEDSTATS 1915 Param: "kvm" - profile VM exits. 1916 1917 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk 1918 before loading. 1919 See Documentation/blockdev/ramdisk.txt. 1920 1921 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to 1922 probe for; one of (bare|imps|exps|lifebook|any). 1923 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports 1924 per second. 1925 psmouse.resetafter= [HW,MOUSE] 1926 Try to reset the device after so many bad packets 1927 (0 = never). 1928 psmouse.resolution= 1929 [HW,MOUSE] Set desired mouse resolution, in dpi. 1930 psmouse.smartscroll= 1931 [HW,MOUSE] Controls Logitech smartscroll autorepeat. 1932 0 = disabled, 1 = enabled (default). 1933 1934 pss= [HW,OSS] Personal Sound System (ECHO ESC614) 1935 Format: 1936 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> 1937 1938 pt. [PARIDE] 1939 See Documentation/blockdev/paride.txt. 1940 1941 pty.legacy_count= 1942 [KNL] Number of legacy pty's. Overwrites compiled-in 1943 default number. 1944 1945 quiet [KNL] Disable most log messages 1946 1947 r128= [HW,DRM] 1948 1949 raid= [HW,RAID] 1950 See Documentation/md.txt. 1951 1952 ramdisk_blocksize= [RAM] 1953 See Documentation/blockdev/ramdisk.txt. 1954 1955 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes 1956 See Documentation/blockdev/ramdisk.txt. 1957 1958 rcupdate.blimit= [KNL,BOOT] 1959 Set maximum number of finished RCU callbacks to process 1960 in one batch. 1961 1962 rcupdate.qhimark= [KNL,BOOT] 1963 Set threshold of queued 1964 RCU callbacks over which batch limiting is disabled. 1965 1966 rcupdate.qlowmark= [KNL,BOOT] 1967 Set threshold of queued RCU callbacks below which 1968 batch limiting is re-enabled. 1969 1970 rdinit= [KNL] 1971 Format: <full_path> 1972 Run specified binary instead of /init from the ramdisk, 1973 used for early userspace startup. See initrd. 1974 1975 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode 1976 Format: <reboot_mode>[,<reboot_mode2>[,...]] 1977 See arch/*/kernel/reboot.c or arch/*/kernel/process.c 1978 1979 relax_domain_level= 1980 [KNL, SMP] Set scheduler's default relax_domain_level. 1981 See Documentation/cgroups/cpusets.txt. 1982 1983 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area 1984 1985 reservetop= [X86-32] 1986 Format: nn[KMG] 1987 Reserves a hole at the top of the kernel virtual 1988 address space. 1989 1990 reset_devices [KNL] Force drivers to reset the underlying device 1991 during initialization. 1992 1993 resume= [SWSUSP] 1994 Specify the partition device for software suspend 1995 1996 resume_offset= [SWSUSP] 1997 Specify the offset from the beginning of the partition 1998 given by "resume=" at which the swap header is located, 1999 in <PAGE_SIZE> units (needed only for swap files). 2000 See Documentation/power/swsusp-and-swap-files.txt
2001 2002 retain_initrd [RAM] Keep initrd memory after extraction 2003 2004 rhash_entries= [KNL,NET] 2005 Set number of hash buckets for route cache 2006 2007 riscom8= [HW,SERIAL] 2008 Format: <io_board1>[,<io_board2>[,...<io_boardN>]] 2009 2010 ro [KNL] Mount root device read-only on boot 2011 2012 root= [KNL] Root filesystem 2013 2014 rootdelay= [KNL] Delay (in seconds) to pause before attempting to 2015 mount the root filesystem 2016 2017 rootflags= [KNL] Set root filesystem mount option string 2018 2019 rootfstype= [KNL] Set root filesystem type 2020 2021 rootwait [KNL] Wait (indefinitely) for root device to show up. 2022 Useful for devices that are detected asynchronously 2023 (e.g. USB and MMC devices). 2024 2025 root_plug.vendor_id= 2026 [ROOTPLUG] Override the default vendor ID 2027 2028 root_plug.product_id= 2029 [ROOTPLUG] Override the default product ID 2030 2031 root_plug.debug= 2032 [ROOTPLUG] Enable debugging output 2033 2034 rw [KNL] Mount root device read-write on boot 2035 2036 S [KNL] Run init in single mode 2037 2038 sa1100ir [NET] 2039 See drivers/net/irda/sa1100_ir.c. 2040 2041 sbni= [NET] Granch SBNI12 leased line adapter 2042 2043 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver 2044 Format: <io>[,<timeout>[,<isapnp>]] 2045 2046 scsi_debug_*= [SCSI] 2047 See drivers/scsi/scsi_debug.c. 2048 2049 scsi_default_dev_flags= 2050 [SCSI] SCSI default device flags 2051 Format: <integer> 2052 2053 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model 2054 Format: <vendor>:<model>:<flags> 2055 (flags are integer value) 2056 2057 scsi_logging_level= [SCSI] a bit mask of logging levels 2058 See drivers/scsi/scsi_logging.h for bits. Also 2059 settable via sysctl at dev.scsi.logging_level 2060 (/proc/sys/dev/scsi/logging_level). 2061 There is also a nice 'scsi_logging_level' script in the 2062 S390-tools package, available for download at 2063 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html 2064 2065 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are 2066 discovered. async scans them in kernel threads, 2067 allowing boot to proceed. none ignores them, expecting 2068 user space to do the scan. 2069 2070 security= [SECURITY] Choose a security module to enable at boot. 2071 If this boot parameter is not specified, only the first 2072 security module asking for security registration will be 2073 loaded. An invalid security module name will be treated 2074 as if no module has been chosen. 2075 2076 selinux= [SELINUX] Disable or enable SELinux at boot time. 2077 Format: { "0" | "1" } 2078 See security/selinux/Kconfig help text. 2079 0 -- disable. 2080 1 -- enable. 2081 Default value is set via kernel config option. 2082 If enabled at boot time, /selinux/disable can be used 2083 later to disable prior to initial policy load. 2084 2085 serialnumber [BUGS=X86-32] 2086 2087 shapers= [NET] 2088 Maximal number of shapers. 2089 2090 show_msr= [x86] show boot-time MSR settings 2091 Format: { <integer> } 2092 Show boot-time (BIOS-initialized) MSR settings. 2093 The parameter means the number of CPUs to show, 2094 for example 1 means boot CPU only. 2095 2096 sim710= [SCSI,HW] 2097 See header of drivers/scsi/sim710.c. 2098 2099 simeth= [IA-64] 2100 simscsi= 2101 2102 slram= [HW,MTD] 2103 2104 slub_debug[=options[,slabs]] [MM, SLUB] 2105 Enabling slub_debug allows one to determine the 2106 culprit if slab objects become corrupted. Enabling 2107 slub_debug can create guard zones around objects and 2108 may poison objects when not in use. Also tracks the 2109 last alloc / free. For more information see 2110 Documentation/vm/slub.txt. 2111 2112 slub_max_order= [MM, SLUB] 2113 Determines the maximum allowed order for slabs. 2114 A high setting may cause OOMs due to memory 2115 fragmentation. For more information see 2116 Documentation/vm/slub.txt. 2117 2118 slub_min_objects= [MM, SLUB] 2119 The minimum number of objects per slab. SLUB will 2120 increase the slab order up to slub_max_order to 2121 generate a sufficiently large slab able to contain 2122 the number of objects indicated. The higher the number 2123 of objects the smaller the overhead of tracking slabs 2124 and the less frequently locks need to be acquired. 2125 For more information see Documentation/vm/slub.txt. 2126 2127 slub_min_order= [MM, SLUB] 2128 Determines the mininum page order for slabs. Must be 2129 lower than slub_max_order. 2130 For more information see Documentation/vm/slub.txt. 2131 2132 slub_nomerge [MM, SLUB] 2133 Disable merging of slabs with similar size. May be 2134 necessary if there is some reason to distinguish 2135 allocs to different slabs. Debug options disable 2136 merging on their own. 2137 For more information see Documentation/vm/slub.txt. 2138 2139 smart2= [HW] 2140 Format: <io1>[,<io2>[,...,<io8>]] 2141 2142 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only 2143 attempt to substitute SMP alternatives once at boot. 2144 2145 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices 2146 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port 2147 smsc-ircc2.ircc_sir= [HW] SIR base I/O port 2148 smsc-ircc2.ircc_fir= [HW] FIR base I/O port 2149 smsc-ircc2.ircc_irq= [HW] IRQ line 2150 smsc-ircc2.ircc_dma= [HW] DMA channel 2151 smsc-ircc2.ircc_transceiver= [HW] Transceiver type: 2152 0: Toshiba Satellite 1800 (GP data pin select) 2153 1: Fast pin select (default) 2154 2: ATC IRMode 2155 2156 snd-ad1816a= [HW,ALSA] 2157 2158 snd-ad1848= [HW,ALSA] 2159 2160 snd-ali5451= [HW,ALSA] 2161 2162 snd-als100= [HW,ALSA] 2163 2164 snd-als4000= [HW,ALSA] 2165 2166 snd-azt2320= [HW,ALSA] 2167 2168 snd-cmi8330= [HW,ALSA] 2169 2170 snd-cmipci= [HW,ALSA] 2171 2172 snd-cs4231= [HW,ALSA] 2173 2174 snd-cs4232= [HW,ALSA] 2175 2176 snd-cs4236= [HW,ALSA] 2177 2178 snd-cs4281= [HW,ALSA] 2179 2180 snd-cs46xx= [HW,ALSA] 2181 2182 snd-dt019x= [HW,ALSA] 2183 2184 snd-dummy= [HW,ALSA] 2185 2186 snd-emu10k1= [HW,ALSA] 2187 2188 snd-ens1370= [HW,ALSA] 2189 2190 snd-ens1371= [HW,ALSA] 2191 2192 snd-es968= [HW,ALSA] 2193 2194 snd-es1688= [HW,ALSA] 2195 2196 snd-es18xx= [HW,ALSA] 2197 2198 snd-es1938= [HW,ALSA] 2199 2200 snd-es1968= [HW,ALSA] 2201 2202 snd-fm801= [HW,ALSA] 2203 2204 snd-gusclassic= [HW,ALSA] 2205 2206 snd-gusextreme= [HW,ALSA] 2207 2208 snd-gusmax= [HW,ALSA] 2209 2210 snd-hdsp= [HW,ALSA] 2211 2212 snd-ice1712= [HW,ALSA] 2213 2214 snd-intel8x0= [HW,ALSA] 2215 2216 snd-interwave= [HW,ALSA] 2217 2218 snd-interwave-stb= 2219 [HW,ALSA] 2220 2221 snd-korg1212= [HW,ALSA] 2222 2223 snd-maestro3= [HW,ALSA] 2224 2225 snd-mpu401= [HW,ALSA] 2226 2227 snd-mtpav= [HW,ALSA] 2228 2229 snd-nm256= [HW,ALSA] 2230 2231 snd-opl3sa2= [HW,ALSA] 2232 2233 snd-opti92x-ad1848= 2234 [HW,ALSA] 2235 2236 snd-opti92x-cs4231= 2237 [HW,ALSA] 2238 2239 snd-opti93x= [HW,ALSA] 2240 2241 snd-pmac= [HW,ALSA] 2242 2243 snd-rme32= [HW,ALSA] 2244 2245 snd-rme96= [HW,ALSA] 2246 2247 snd-rme9652= [HW,ALSA] 2248 2249 snd-sb8= [HW,ALSA] 2250 2251 snd-sb16= [HW,ALSA] 2252 2253 snd-sbawe= [HW,ALSA] 2254 2255 snd-serial= [HW,ALSA] 2256 2257 snd-sgalaxy= [HW,ALSA] 2258 2259 snd-sonicvibes= [HW,ALSA] 2260 2261 snd-sun-amd7930= 2262 [HW,ALSA] 2263 2264 snd-sun-cs4231= [HW,ALSA] 2265 2266 snd-trident= [HW,ALSA] 2267 2268 snd-usb-audio= [HW,ALSA,USB] 2269 2270 snd-via82xx= [HW,ALSA] 2271 2272 snd-virmidi= [HW,ALSA] 2273 2274 snd-wavefront= [HW,ALSA] 2275 2276 snd-ymfpci= [HW,ALSA] 2277 2278 softlockup_panic= 2279 [KNL] Should the soft-lockup detector generate panics. 2280 2281 sonypi.*= [HW] Sony Programmable I/O Control Device driver 2282 See Documentation/sonypi.txt 2283 2284 specialix= [HW,SERIAL] Specialix multi-serial port adapter 2285 See Documentation/serial/specialix.txt. 2286 2287 spia_io_base= [HW,MTD] 2288 spia_fio_base= 2289 spia_pedr= 2290 spia_peddr= 2291 2292 sscape= [HW,OSS] 2293 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq> 2294 2295 st= [HW,SCSI] SCSI tape parameters (buffers, etc.) 2296 See Documentation/scsi/st.txt. 2297 2298 stacktrace [FTRACE] 2299 Enabled the stack tracer on boot up. 2300 2301 sti= [PARISC,HW] 2302 Format: <num> 2303 Set the STI (builtin display/keyboard on the HP-PARISC 2304 machines) console (graphic card) which should be used 2305 as the initial boot-console. 2306 See also comment in drivers/video/console/sticore.c. 2307 2308 sti_font= [HW] 2309 See comment in drivers/video/console/sticore.c. 2310 2311 stifb= [HW] 2312 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] 2313 2314 sunrpc.pool_mode= 2315 [NFS] 2316 Control how the NFS server code allocates CPUs to 2317 service thread pools. Depending on how many NICs 2318 you have and where their interrupts are bound, this 2319 option will affect which CPUs will do NFS serving. 2320 Note: this parameter cannot be changed while the 2321 NFS server is running. 2322 2323 auto the server chooses an appropriate mode 2324 automatically using heuristics 2325 global a single global pool contains all CPUs 2326 percpu one pool for each CPU 2327 pernode one pool for each NUMA node (equivalent 2328 to global on non-NUMA machines) 2329 2330 swiotlb= [IA-64] Number of I/O TLB slabs 2331 2332 switches= [HW,M68k] 2333 2334 sym53c416= [HW,SCSI] 2335 See header of drivers/scsi/sym53c416.c. 2336 2337 sysrq_always_enabled 2338 [KNL] 2339 Ignore sysrq setting - this boot parameter will 2340 neutralize any effect of /proc/sys/kernel/sysrq. 2341 Useful for debugging. 2342 2343 t128= [HW,SCSI] 2344 See header of drivers/scsi/t128.c. 2345 2346 tdfx= [HW,DRM] 2347 2348 test_suspend= [SUSPEND] 2349 Specify "mem" (for Suspend-to-RAM) or "standby" (for 2350 standby suspend) as the system sleep state to briefly 2351 enter during system startup. The system is woken from 2352 this state using a wakeup-capable RTC alarm. 2353 2354 thash_entries= [KNL,NET] 2355 Set number of hash buckets for TCP connection 2356 2357 thermal.act= [HW,ACPI] 2358 -1: disable all active trip points in all thermal zones 2359 <degrees C>: override all lowest active trip points 2360 2361 thermal.crt= [HW,ACPI] 2362 -1: disable all critical trip points in all thermal zones 2363 <degrees C>: override all critical trip points 2364 2365 thermal.nocrt= [HW,ACPI] 2366 Set to disable actions on ACPI thermal zone 2367 critical and hot trip points. 2368 2369 thermal.off= [HW,ACPI] 2370 1: disable ACPI thermal control 2371 2372 thermal.psv= [HW,ACPI] 2373 -1: disable all passive trip points 2374 <degrees C>: override all passive trip points to this 2375 value 2376 2377 thermal.tzp= [HW,ACPI] 2378 Specify global default ACPI thermal zone polling rate 2379 <deci-seconds>: poll all this frequency 2380 0: no polling (default) 2381 2382 tmscsim= [HW,SCSI] 2383 See comment before function dc390_setup() in 2384 drivers/scsi/tmscsim.c. 2385 2386 topology= [S390] 2387 Format: {off | on} 2388 Specify if the kernel should make use of the cpu 2389 topology informations if the hardware supports these. 2390 The scheduler will make use of these informations and 2391 e.g. base its process migration decisions on it. 2392 Default is off. 2393 2394 tp720= [HW,PS2] 2395 2396 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size. 2397 2398 trix= [HW,OSS] MediaTrix AudioTrix Pro 2399 Format: 2400 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq> 2401 2402 tsc= Disable clocksource-must-verify flag for TSC. 2403 Format: <string> 2404 [x86] reliable: mark tsc clocksource as reliable, this 2405 disables clocksource verification at runtime. 2406 Used to enable high-resolution timer mode on older 2407 hardware, and in virtualized environment. 2408 2409 turbografx.map[2|3]= [HW,JOY] 2410 TurboGraFX parallel port interface 2411 Format: 2412 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> 2413 See also Documentation/input/joystick-parport.txt 2414 2415 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter 2416 See header of drivers/scsi/u14-34f.c. 2417 2418 uart401= [HW,OSS] 2419 Format: <io>,<irq> 2420 2421 uart6850= [HW,OSS] 2422 Format: <io>,<irq> 2423 2424 uhci-hcd.ignore_oc= 2425 [USB] Ignore overcurrent events (default N). 2426 Some badly-designed motherboards generate lots of 2427 bogus events, for ports that aren't wired to 2428 anything. Set this parameter to avoid log spamming. 2429 Note that genuine overcurrent events won't be 2430 reported either. 2431 2432 unknown_nmi_panic 2433 [X86] 2434 Set unknown_nmi_panic=1 early on boot. 2435 2436 usbcore.autosuspend= 2437 [USB] The autosuspend time delay (in seconds) used 2438 for newly-detected USB devices (default 2). This 2439 is the time required before an idle device will be 2440 autosuspended. Devices for which the delay is set 2441 to a negative value won't be autosuspended at all. 2442 2443 usbcore.usbfs_snoop= 2444 [USB] Set to log all usbfs traffic (default 0 = off). 2445 2446 usbcore.blinkenlights= 2447 [USB] Set to cycle leds on hubs (default 0 = off). 2448 2449 usbcore.old_scheme_first= 2450 [USB] Start with the old device initialization 2451 scheme (default 0 = off). 2452 2453 usbcore.use_both_schemes= 2454 [USB] Try the other device initialization scheme 2455 if the first one fails (default 1 = enabled). 2456 2457 usbcore.initial_descriptor_timeout= 2458 [USB] Specifies timeout for the initial 64-byte 2459 USB_REQ_GET_DESCRIPTOR request in milliseconds 2460 (default 5000 = 5.0 seconds). 2461 2462 usbhid.mousepoll= 2463 [USBHID] The interval which mice are to be polled at. 2464 2465 usb-storage.delay_use= 2466 [UMS] The delay in seconds before a new device is 2467 scanned for Logical Units (default 5). 2468 2469 usb-storage.quirks= 2470 [UMS] A list of quirks entries to supplement or 2471 override the built-in unusual_devs list. List 2472 entries are separated by commas. Each entry has 2473 the form VID:PID:Flags where VID and PID are Vendor 2474 and Product ID values (4-digit hex numbers) and 2475 Flags is a set of characters, each corresponding 2476 to a common usb-storage quirk flag as follows: 2477 a = SANE_SENSE (collect more than 18 bytes 2478 of sense data); 2479 c = FIX_CAPACITY (decrease the reported 2480 device capacity by one sector); 2481 h = CAPACITY_HEURISTICS (decrease the 2482 reported device capacity by one 2483 sector if the number is odd); 2484 i = IGNORE_DEVICE (don't bind to this 2485 device); 2486 l = NOT_LOCKABLE (don't try to lock and 2487 unlock ejectable media); 2488 m = MAX_SECTORS_64 (don't transfer more 2489 than 64 sectors = 32 KB at a time); 2490 o = CAPACITY_OK (accept the capacity 2491 reported by the device); 2492 r = IGNORE_RESIDUE (the device reports 2493 bogus residue values); 2494 s = SINGLE_LUN (the device has only one 2495 Logical Unit); 2496 w = NO_WP_DETECT (don't test whether the 2497 medium is write-protected). 2498 Example: quirks=0419:aaf5:rl,0421:0433:rc 2499 2500 vdso= [X86,SH] 2501 vdso=2: enable compat VDSO (default with COMPAT_VDSO) 2502 vdso=1: enable VDSO (default) 2503 vdso=0: disable VDSO mapping 2504 2505 vdso32= [X86] 2506 vdso32=2: enable compat VDSO (default with COMPAT_VDSO) 2507 vdso32=1: enable 32-bit VDSO (default) 2508 vdso32=0: disable 32-bit VDSO mapping 2509 2510 vector= [IA-64,SMP] 2511 vector=percpu: enable percpu vector domain 2512 2513 video= [FB] Frame buffer configuration 2514 See Documentation/fb/modedb.txt. 2515 2516 vga= [BOOT,X86-32] Select a particular video mode 2517 See Documentation/x86/boot.txt and 2518 Documentation/svga.txt. 2519 Use vga=ask for menu. 2520 This is actually a boot loader parameter; the value is 2521 passed to the kernel using a special protocol. 2522 2523 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact 2524 size of <nn>. This can be used to increase the 2525 minimum size (128MB on x86). It can also be used to 2526 decrease the size and leave more room for directly 2527 mapped kernel RAM. 2528 2529 vmhalt= [KNL,S390] Perform z/VM CP command after system halt. 2530 Format: <command> 2531 2532 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. 2533 Format: <command> 2534 2535 vmpoff= [KNL,S390] Perform z/VM CP command after power off. 2536 Format: <command> 2537 2538 vt.default_blu= [VT] 2539 Format: <blue0>,<blue1>,<blue2>,...,<blue15> 2540 Change the default blue palette of the console. 2541 This is a 16-member array composed of values 2542 ranging from 0-255. 2543 2544 vt.default_grn= [VT] 2545 Format: <green0>,<green1>,<green2>,...,<green15> 2546 Change the default green palette of the console. 2547 This is a 16-member array composed of values 2548 ranging from 0-255. 2549 2550 vt.default_red= [VT] 2551 Format: <red0>,<red1>,<red2>,...,<red15> 2552 Change the default red palette of the console. 2553 This is a 16-member array composed of values 2554 ranging from 0-255. 2555 2556 vt.default_utf8= 2557 [VT] 2558 Format=<0|1> 2559 Set system-wide default UTF-8 mode for all tty's. 2560 Default is 1, i.e. UTF-8 mode is enabled for all 2561 newly opened terminals. 2562 2563 waveartist= [HW,OSS] 2564 Format: <io>,<irq>,<dma>,<dma2> 2565 2566 wd33c93= [HW,SCSI] 2567 See header of drivers/scsi/wd33c93.c. 2568 2569 wd7000= [HW,SCSI] 2570 See header of drivers/scsi/wd7000.c. 2571 2572 wdt= [WDT] Watchdog 2573 See Documentation/watchdog/wdt.txt. 2574 2575 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of 2576 default x2apic cluster mode on platforms 2577 supporting x2apic. 2578 2579 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. 2580 xd_geo= See header of drivers/block/xd.c. 2581 2582 xirc2ps_cs= [NET,PCMCIA] 2583 Format: 2584 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] 2585 2586______________________________________________________________________ 2587 2588TODO: 2589 2590 Add documentation for ALSA options. 2591 Add more DRM drivers. 2592