linux/Documentation/kernel-parameters.txt
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   1                          Kernel Parameters
   2                          ~~~~~~~~~~~~~~~~~
   3
   4The following is a consolidated list of the kernel parameters as implemented
   5(mostly) by the __setup() macro and sorted into English Dictionary order
   6(defined as ignoring all punctuation and sorting digits before letters in a
   7case insensitive manner), and with descriptions where known.
   8
   9Module parameters for loadable modules are specified only as the
  10parameter name with optional '=' and value as appropriate, such as:
  11
  12        modprobe usbcore blinkenlights=1
  13
  14Module parameters for modules that are built into the kernel image
  15are specified on the kernel command line with the module name plus
  16'.' plus parameter name, with '=' and value if appropriate, such as:
  17
  18        usbcore.blinkenlights=1
  19
  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        GCOV    GCOV profiling is enabled.
  52        HW      Appropriate hardware is enabled.
  53        IA-64   IA-64 architecture is enabled.
  54        IMA     Integrity measurement architecture is enabled.
  55        IOSCHED More than one I/O scheduler is enabled.
  56        IP_PNP  IP DHCP, BOOTP, or RARP is enabled.
  57        ISAPNP  ISA PnP code is enabled.
  58        ISDN    Appropriate ISDN support is enabled.
  59        JOY     Appropriate joystick support is enabled.
  60        KVM     Kernel Virtual Machine support is enabled.
  61        LIBATA  Libata driver is enabled
  62        LP      Printer support is enabled.
  63        LOOP    Loopback device support is enabled.
  64        M68k    M68k architecture is enabled.
  65                        These options have more detailed description inside of
  66                        Documentation/m68k/kernel-options.txt.
  67        MCA     MCA bus support is enabled.
  68        MDA     MDA console support is enabled.
  69        MOUSE   Appropriate mouse support is enabled.
  70        MSI     Message Signaled Interrupts (PCI).
  71        MTD     MTD (Memory Technology Device) support is enabled.
  72        NET     Appropriate network support is enabled.
  73        NUMA    NUMA support is enabled.
  74        GENERIC_TIME The generic timeofday code is enabled.
  75        NFS     Appropriate NFS support is enabled.
  76        OSS     OSS sound support is enabled.
  77        PV_OPS  A paravirtualized kernel is enabled.
  78        PARIDE  The ParIDE (parallel port IDE) subsystem is enabled.
  79        PARISC  The PA-RISC architecture is enabled.
  80        PCI     PCI bus support is enabled.
  81        PCIE    PCI Express support is enabled.
  82        PCMCIA  The PCMCIA subsystem is enabled.
  83        PNP     Plug & Play support is enabled.
  84        PPC     PowerPC architecture is enabled.
  85        PPT     Parallel port support is enabled.
  86        PS2     Appropriate PS/2 support is enabled.
  87        RAM     RAM disk support is enabled.
  88        ROOTPLUG The example Root Plug LSM is enabled.
  89        S390    S390 architecture is enabled.
  90        SCSI    Appropriate SCSI support is enabled.
  91                        A lot of drivers has their options described inside of
  92                        Documentation/scsi/.
  93        SECURITY Different security models are enabled.
  94        SELINUX SELinux support is enabled.
  95        SERIAL  Serial support is enabled.
  96        SH      SuperH architecture is enabled.
  97        SMP     The kernel is an SMP kernel.
  98        SPARC   Sparc architecture is enabled.
  99        SWSUSP  Software suspend (hibernation) is enabled.
 100        SUSPEND System suspend states are enabled.
 101        FTRACE  Function tracing enabled.
 102        TS      Appropriate touchscreen support is enabled.
 103        UMS     USB Mass Storage support is enabled.
 104        USB     USB support is enabled.
 105        USBHID  USB Human Interface Device support is enabled.
 106        V4L     Video For Linux support is enabled.
 107        VGA     The VGA console has been enabled.
 108        VT      Virtual terminal support is enabled.
 109        WDT     Watchdog support is enabled.
 110        XT      IBM PC/XT MFM hard disk support is enabled.
 111        X86-32  X86-32, aka i386 architecture is enabled.
 112        X86-64  X86-64 architecture is enabled.
 113                        More X86-64 boot options can be found in
 114                        Documentation/x86/x86_64/boot-options.txt .
 115        X86     Either 32bit or 64bit x86 (same as X86-32+X86-64)
 116
 117In addition, the following text indicates that the option:
 118
 119        BUGS=   Relates to possible processor bugs on the said processor.
 120        KNL     Is a kernel start-up parameter.
 121        BOOT    Is a boot loader parameter.
 122
 123Parameters denoted with BOOT are actually interpreted by the boot
 124loader, and have no meaning to the kernel directly.
 125Do not modify the syntax of boot loader parameters without extreme
 126need or coordination with <Documentation/x86/boot.txt>.
 127
 128There are also arch-specific kernel-parameters not documented here.
 129See for example <Documentation/x86/x86_64/boot-options.txt>.
 130
 131Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
 132a trailing = on the name of any parameter states that that parameter will
 133be entered as an environment variable, whereas its absence indicates that
 134it will appear as a kernel argument readable via /proc/cmdline by programs
 135running once the system is up.
 136
 137The number of kernel parameters is not limited, but the length of the
 138complete command line (parameters including spaces etc.) is limited to
 139a fixed number of characters. This limit depends on the architecture
 140and is between 256 and 4096 characters. It is defined in the file
 141./include/asm/setup.h as COMMAND_LINE_SIZE.
 142
 143
 144        acpi=           [HW,ACPI,X86]
 145                        Advanced Configuration and Power Interface
 146                        Format: { force | off | ht | strict | noirq | rsdt }
 147                        force -- enable ACPI if default was off
 148                        off -- disable ACPI if default was on
 149                        noirq -- do not use ACPI for IRQ routing
 150                        ht -- run only enough ACPI to enable Hyper Threading
 151                        strict -- Be less tolerant of platforms that are not
 152                                strictly ACPI specification compliant.
 153                        rsdt -- prefer RSDT over (default) XSDT
 154
 155                        See also Documentation/power/pm.txt, pci=noacpi
 156
 157        acpi_apic_instance=     [ACPI, IOAPIC]
 158                        Format: <int>
 159                        2: use 2nd APIC table, if available
 160                        1,0: use 1st APIC table
 161                        default: 0
 162
 163        acpi_backlight= [HW,ACPI]
 164                        acpi_backlight=vendor
 165                        acpi_backlight=video
 166                        If set to vendor, prefer vendor specific driver
 167                        (e.g. thinkpad_acpi, sony_acpi, etc.) instead
 168                        of the ACPI video.ko driver.
 169
 170        acpi.debug_layer=       [HW,ACPI,ACPI_DEBUG]
 171        acpi.debug_level=       [HW,ACPI,ACPI_DEBUG]
 172                        Format: <int>
 173                        CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
 174                        debug output.  Bits in debug_layer correspond to a
 175                        _COMPONENT in an ACPI source file, e.g.,
 176                            #define _COMPONENT ACPI_PCI_COMPONENT
 177                        Bits in debug_level correspond to a level in
 178                        ACPI_DEBUG_PRINT statements, e.g.,
 179                            ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
 180                        The debug_level mask defaults to "info".  See
 181                        Documentation/acpi/debug.txt for more information about
 182                        debug layers and levels.
 183
 184                        Enable processor driver info messages:
 185                            acpi.debug_layer=0x20000000
 186                        Enable PCI/PCI interrupt routing info messages:
 187                            acpi.debug_layer=0x400000
 188                        Enable AML "Debug" output, i.e., stores to the Debug
 189                        object while interpreting AML:
 190                            acpi.debug_layer=0xffffffff acpi.debug_level=0x2
 191                        Enable all messages related to ACPI hardware:
 192                            acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
 193
 194                        Some values produce so much output that the system is
 195                        unusable.  The "log_buf_len" parameter may be useful
 196                        if you need to capture more output.
 197
 198        acpi_display_output=    [HW,ACPI]
 199                        acpi_display_output=vendor
 200                        acpi_display_output=video
 201                        See above.
 202
 203        acpi_irq_balance [HW,ACPI]
 204                        ACPI will balance active IRQs
 205                        default in APIC mode
 206
 207        acpi_irq_nobalance [HW,ACPI]
 208                        ACPI will not move active IRQs (default)
 209                        default in PIC mode
 210
 211        acpi_irq_isa=   [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
 212                        Format: <irq>,<irq>...
 213
 214        acpi_irq_pci=   [HW,ACPI] If irq_balance, clear listed IRQs for
 215                        use by PCI
 216                        Format: <irq>,<irq>...
 217
 218        acpi_no_auto_ssdt       [HW,ACPI] Disable automatic loading of SSDT
 219
 220        acpi_os_name=   [HW,ACPI] Tell ACPI BIOS the name of the OS
 221                        Format: To spoof as Windows 98: ="Microsoft Windows"
 222
 223        acpi_osi=       [HW,ACPI] Modify list of supported OS interface strings
 224                        acpi_osi="string1"      # add string1 -- only one string
 225                        acpi_osi="!string2"     # remove built-in string2
 226                        acpi_osi=               # disable all strings
 227
 228        acpi_pm_good    [X86]
 229                        Override the pmtimer bug detection: force the kernel
 230                        to assume that this machine's pmtimer latches its value
 231                        and always returns good values.
 232
 233        acpi_sci=       [HW,ACPI] ACPI System Control Interrupt trigger mode
 234                        Format: { level | edge | high | low }
 235
 236        acpi_serialize  [HW,ACPI] force serialization of AML methods
 237
 238        acpi_skip_timer_override [HW,ACPI]
 239                        Recognize and ignore IRQ0/pin2 Interrupt Override.
 240                        For broken nForce2 BIOS resulting in XT-PIC timer.
 241
 242        acpi_sleep=     [HW,ACPI] Sleep options
 243                        Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
 244                                  old_ordering, s4_nonvs }
 245                        See Documentation/power/video.txt for information on
 246                        s3_bios and s3_mode.
 247                        s3_beep is for debugging; it makes the PC's speaker beep
 248                        as soon as the kernel's real-mode entry point is called.
 249                        s4_nohwsig prevents ACPI hardware signature from being
 250                        used during resume from hibernation.
 251                        old_ordering causes the ACPI 1.0 ordering of the _PTS
 252                        control method, with respect to putting devices into
 253                        low power states, to be enforced (the ACPI 2.0 ordering
 254                        of _PTS is used by default).
 255                        s4_nonvs prevents the kernel from saving/restoring the
 256                        ACPI NVS memory during hibernation.
 257
 258        acpi_use_timer_override [HW,ACPI]
 259                        Use timer override. For some broken Nvidia NF5 boards
 260                        that require a timer override, but don't have HPET
 261
 262        acpi_enforce_resources= [ACPI]
 263                        { strict | lax | no }
 264                        Check for resource conflicts between native drivers
 265                        and ACPI OperationRegions (SystemIO and SystemMemory
 266                        only). IO ports and memory declared in ACPI might be
 267                        used by the ACPI subsystem in arbitrary AML code and
 268                        can interfere with legacy drivers.
 269                        strict (default): access to resources claimed by ACPI
 270                        is denied; legacy drivers trying to access reserved
 271                        resources will fail to bind to device using them.
 272                        lax: access to resources claimed by ACPI is allowed;
 273                        legacy drivers trying to access reserved resources
 274                        will bind successfully but a warning message is logged.
 275                        no: ACPI OperationRegions are not marked as reserved,
 276                        no further checks are performed.
 277
 278        ad1848=         [HW,OSS]
 279                        Format: <io>,<irq>,<dma>,<dma2>,<type>
 280
 281        add_efi_memmap  [EFI; X86] Include EFI memory map in
 282                        kernel's map of available physical RAM.
 283
 284        advansys=       [HW,SCSI]
 285                        See header of drivers/scsi/advansys.c.
 286
 287        advwdt=         [HW,WDT] Advantech WDT
 288                        Format: <iostart>,<iostop>
 289
 290        aedsp16=        [HW,OSS] Audio Excel DSP 16
 291                        Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
 292                        See also header of sound/oss/aedsp16.c.
 293
 294        agp=            [AGP]
 295                        { off | try_unsupported }
 296                        off: disable AGP support
 297                        try_unsupported: try to drive unsupported chipsets
 298                                (may crash computer or cause data corruption)
 299
 300        aha152x=        [HW,SCSI]
 301                        See Documentation/scsi/aha152x.txt.
 302
 303        aha1542=        [HW,SCSI]
 304                        Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
 305
 306        aic7xxx=        [HW,SCSI]
 307                        See Documentation/scsi/aic7xxx.txt.
 308
 309        aic79xx=        [HW,SCSI]
 310                        See Documentation/scsi/aic79xx.txt.
 311
 312        amd_iommu=      [HW,X86-84]
 313                        Pass parameters to the AMD IOMMU driver in the system.
 314                        Possible values are:
 315                        isolate - enable device isolation (each device, as far
 316                                  as possible, will get its own protection
 317                                  domain) [default]
 318                        share - put every device behind one IOMMU into the
 319                                same protection domain
 320                        fullflush - enable flushing of IO/TLB entries when
 321                                    they are unmapped. Otherwise they are
 322                                    flushed before they will be reused, which
 323                                    is a lot of faster
 324
 325        amijoy.map=     [HW,JOY] Amiga joystick support
 326                        Map of devices attached to JOY0DAT and JOY1DAT
 327                        Format: <a>,<b>
 328                        See also Documentation/kernel/input/joystick.txt
 329
 330        analog.map=     [HW,JOY] Analog joystick and gamepad support
 331                        Specifies type or capabilities of an analog joystick
 332                        connected to one of 16 gameports
 333                        Format: <type1>,<type2>,..<type16>
 334
 335        apc=            [HW,SPARC]
 336                        Power management functions (SPARCstation-4/5 + deriv.)
 337                        Format: noidle
 338                        Disable APC CPU standby support. SPARCstation-Fox does
 339                        not play well with APC CPU idle - disable it if you have
 340                        APC and your system crashes randomly.
 341
 342        apic=           [APIC,X86-32] Advanced Programmable Interrupt Controller
 343                        Change the output verbosity whilst booting
 344                        Format: { quiet (default) | verbose | debug }
 345                        Change the amount of debugging information output
 346                        when initialising the APIC and IO-APIC components.
 347
 348        apm=            [APM] Advanced Power Management
 349                        See header of arch/x86/kernel/apm_32.c.
 350
 351        arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
 352                        Format: <io>,<irq>,<nodeID>
 353
 354        ataflop=        [HW,M68k]
 355
 356        atarimouse=     [HW,MOUSE] Atari Mouse
 357
 358        atascsi=        [HW,SCSI] Atari SCSI
 359
 360        atkbd.extra=    [HW] Enable extra LEDs and keys on IBM RapidAccess,
 361                        EzKey and similar keyboards
 362
 363        atkbd.reset=    [HW] Reset keyboard during initialization
 364
 365        atkbd.set=      [HW] Select keyboard code set
 366                        Format: <int> (2 = AT (default), 3 = PS/2)
 367
 368        atkbd.scroll=   [HW] Enable scroll wheel on MS Office and similar
 369                        keyboards
 370
 371        atkbd.softraw=  [HW] Choose between synthetic and real raw mode
 372                        Format: <bool> (0 = real, 1 = synthetic (default))
 373
 374        atkbd.softrepeat= [HW]
 375                        Use software keyboard repeat
 376
 377        autotest        [IA64]
 378
 379        baycom_epp=     [HW,AX25]
 380                        Format: <io>,<mode>
 381
 382        baycom_par=     [HW,AX25] BayCom Parallel Port AX.25 Modem
 383                        Format: <io>,<mode>
 384                        See header of drivers/net/hamradio/baycom_par.c.
 385
 386        baycom_ser_fdx= [HW,AX25]
 387                        BayCom Serial Port AX.25 Modem (Full Duplex Mode)
 388                        Format: <io>,<irq>,<mode>[,<baud>]
 389                        See header of drivers/net/hamradio/baycom_ser_fdx.c.
 390
 391        baycom_ser_hdx= [HW,AX25]
 392                        BayCom Serial Port AX.25 Modem (Half Duplex Mode)
 393                        Format: <io>,<irq>,<mode>
 394                        See header of drivers/net/hamradio/baycom_ser_hdx.c.
 395
 396        boot_delay=     Milliseconds to delay each printk during boot.
 397                        Values larger than 10 seconds (10000) are changed to
 398                        no delay (0).
 399                        Format: integer
 400
 401        bootmem_debug   [KNL] Enable bootmem allocator debug messages.
 402
 403        bttv.card=      [HW,V4L] bttv (bt848 + bt878 based grabber cards)
 404        bttv.radio=     Most important insmod options are available as
 405                        kernel args too.
 406        bttv.pll=       See Documentation/video4linux/bttv/Insmod-options
 407        bttv.tuner=     and Documentation/video4linux/bttv/CARDLIST
 408
 409        BusLogic=       [HW,SCSI]
 410                        See drivers/scsi/BusLogic.c, comment before function
 411                        BusLogic_ParseDriverOptions().
 412
 413        c101=           [NET] Moxa C101 synchronous serial card
 414
 415        cachesize=      [BUGS=X86-32] Override level 2 CPU cache size detection.
 416                        Sometimes CPU hardware bugs make them report the cache
 417                        size incorrectly. The kernel will attempt work arounds
 418                        to fix known problems, but for some CPUs it is not
 419                        possible to determine what the correct size should be.
 420                        This option provides an override for these situations.
 421
 422        capability.disable=
 423                        [SECURITY] Disable capabilities.  This would normally
 424                        be used only if an alternative security model is to be
 425                        configured.  Potentially dangerous and should only be
 426                        used if you are entirely sure of the consequences.
 427
 428        ccw_timeout_log [S390]
 429                        See Documentation/s390/CommonIO for details.
 430
 431        cgroup_disable= [KNL] Disable a particular controller
 432                        Format: {name of the controller(s) to disable}
 433                                {Currently supported controllers - "memory"}
 434
 435        checkreqprot    [SELINUX] Set initial checkreqprot flag value.
 436                        Format: { "0" | "1" }
 437                        See security/selinux/Kconfig help text.
 438                        0 -- check protection applied by kernel (includes
 439                                any implied execute protection).
 440                        1 -- check protection requested by application.
 441                        Default value is set via a kernel config option.
 442                        Value can be changed at runtime via
 443                                /selinux/checkreqprot.
 444
 445        cio_ignore=     [S390]
 446                        See Documentation/s390/CommonIO for details.
 447
 448        clock=          [BUGS=X86-32, HW] gettimeofday clocksource override.
 449                        [Deprecated]
 450                        Forces specified clocksource (if available) to be used
 451                        when calculating gettimeofday(). If specified
 452                        clocksource is not available, it defaults to PIT.
 453                        Format: { pit | tsc | cyclone | pmtmr }
 454
 455        clocksource=    [GENERIC_TIME] Override the default clocksource
 456                        Format: <string>
 457                        Override the default clocksource and use the clocksource
 458                        with the name specified.
 459                        Some clocksource names to choose from, depending on
 460                        the platform:
 461                        [all] jiffies (this is the base, fallback clocksource)
 462                        [ACPI] acpi_pm
 463                        [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
 464                                pxa_timer,timer3,32k_counter,timer0_1
 465                        [AVR32] avr32
 466                        [X86-32] pit,hpet,tsc,vmi-timer;
 467                                scx200_hrt on Geode; cyclone on IBM x440
 468                        [MIPS] MIPS
 469                        [PARISC] cr16
 470                        [S390] tod
 471                        [SH] SuperH
 472                        [SPARC64] tick
 473                        [X86-64] hpet,tsc
 474
 475        clearcpuid=BITNUM [X86]
 476                        Disable CPUID feature X for the kernel. See
 477                        arch/x86/include/asm/cpufeature.h for the valid bit
 478                        numbers. Note the Linux specific bits are not necessarily
 479                        stable over kernel options, but the vendor specific
 480                        ones should be.
 481                        Also note that user programs calling CPUID directly
 482                        or using the feature without checking anything
 483                        will still see it. This just prevents it from
 484                        being used by the kernel or shown in /proc/cpuinfo.
 485                        Also note the kernel might malfunction if you disable
 486                        some critical bits.
 487
 488        cmo_free_hint=  [PPC] Format: { yes | no }
 489                        Specify whether pages are marked as being inactive
 490                        when they are freed.  This is used in CMO environments
 491                        to determine OS memory pressure for page stealing by
 492                        a hypervisor.
 493                        Default: yes
 494
 495        code_bytes      [X86] How many bytes of object code to print
 496                        in an oops report.
 497                        Range: 0 - 8192
 498                        Default: 64
 499
 500        com20020=       [HW,NET] ARCnet - COM20020 chipset
 501                        Format:
 502                        <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
 503
 504        com90io=        [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
 505                        Format: <io>[,<irq>]
 506
 507        com90xx=        [HW,NET]
 508                        ARCnet - COM90xx chipset (memory-mapped buffers)
 509                        Format: <io>[,<irq>[,<memstart>]]
 510
 511        condev=         [HW,S390] console device
 512        conmode=
 513
 514        console=        [KNL] Output console device and options.
 515
 516                tty<n>  Use the virtual console device <n>.
 517
 518                ttyS<n>[,options]
 519                ttyUSB0[,options]
 520                        Use the specified serial port.  The options are of
 521                        the form "bbbbpnf", where "bbbb" is the baud rate,
 522                        "p" is parity ("n", "o", or "e"), "n" is number of
 523                        bits, and "f" is flow control ("r" for RTS or
 524                        omit it).  Default is "9600n8".
 525
 526                        See Documentation/serial-console.txt for more
 527                        information.  See
 528                        Documentation/networking/netconsole.txt for an
 529                        alternative.
 530
 531                uart[8250],io,<addr>[,options]
 532                uart[8250],mmio,<addr>[,options]
 533                        Start an early, polled-mode console on the 8250/16550
 534                        UART at the specified I/O port or MMIO address,
 535                        switching to the matching ttyS device later.  The
 536                        options are the same as for ttyS, above.
 537
 538                If the device connected to the port is not a TTY but a braille
 539                device, prepend "brl," before the device type, for instance
 540                        console=brl,ttyS0
 541                For now, only VisioBraille is supported.
 542
 543        consoleblank=   [KNL] The console blank (screen saver) timeout in
 544                        seconds. Defaults to 10*60 = 10mins. A value of 0
 545                        disables the blank timer.
 546
 547        coredump_filter=
 548                        [KNL] Change the default value for
 549                        /proc/<pid>/coredump_filter.
 550                        See also Documentation/filesystems/proc.txt.
 551
 552        cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
 553                        Format:
 554                        <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
 555
 556        crashkernel=nn[KMG]@ss[KMG]
 557                        [KNL] Reserve a chunk of physical memory to
 558                        hold a kernel to switch to with kexec on panic.
 559
 560        crashkernel=range1:size1[,range2:size2,...][@offset]
 561                        [KNL] Same as above, but depends on the memory
 562                        in the running system. The syntax of range is
 563                        start-[end] where start and end are both
 564                        a memory unit (amount[KMG]). See also
 565                        Documentation/kdump/kdump.txt for a example.
 566
 567        cs89x0_dma=     [HW,NET]
 568                        Format: <dma>
 569
 570        cs89x0_media=   [HW,NET]
 571                        Format: { rj45 | aui | bnc }
 572
 573        dasd=           [HW,NET]
 574                        See header of drivers/s390/block/dasd_devmap.c.
 575
 576        db9.dev[2|3]=   [HW,JOY] Multisystem joystick support via parallel port
 577                        (one device per port)
 578                        Format: <port#>,<type>
 579                        See also Documentation/input/joystick-parport.txt
 580
 581        debug           [KNL] Enable kernel debugging (events log level).
 582
 583        debug_locks_verbose=
 584                        [KNL] verbose self-tests
 585                        Format=<0|1>
 586                        Print debugging info while doing the locking API
 587                        self-tests.
 588                        We default to 0 (no extra messages), setting it to
 589                        1 will print _a lot_ more information - normally
 590                        only useful to kernel developers.
 591
 592        debug_objects   [KNL] Enable object debugging
 593
 594        no_debug_objects
 595                        [KNL] Disable object debugging
 596
 597        debugpat        [X86] Enable PAT debugging
 598
 599        decnet.addr=    [HW,NET]
 600                        Format: <area>[,<node>]
 601                        See also Documentation/networking/decnet.txt.
 602
 603        default_hugepagesz=
 604                        [same as hugepagesz=] The size of the default
 605                        HugeTLB page size. This is the size represented by
 606                        the legacy /proc/ hugepages APIs, used for SHM, and
 607                        default size when mounting hugetlbfs filesystems.
 608                        Defaults to the default architecture's huge page size
 609                        if not specified.
 610
 611        dhash_entries=  [KNL]
 612                        Set number of hash buckets for dentry cache.
 613
 614        digi=           [HW,SERIAL]
 615                        IO parameters + enable/disable command.
 616
 617        digiepca=       [HW,SERIAL]
 618                        See drivers/char/README.epca and
 619                        Documentation/serial/digiepca.txt.
 620
 621        disable_mtrr_cleanup [X86]
 622                        The kernel tries to adjust MTRR layout from continuous
 623                        to discrete, to make X server driver able to add WB
 624                        entry later. This parameter disables that.
 625
 626        disable_mtrr_trim [X86, Intel and AMD only]
 627                        By default the kernel will trim any uncacheable
 628                        memory out of your available memory pool based on
 629                        MTRR settings.  This parameter disables that behavior,
 630                        possibly causing your machine to run very slowly.
 631
 632        disable_timer_pin_1 [X86]
 633                        Disable PIN 1 of APIC timer
 634                        Can be useful to work around chipset bugs.
 635
 636        dmasound=       [HW,OSS] Sound subsystem buffers
 637
 638        dma_debug=off   If the kernel is compiled with DMA_API_DEBUG support,
 639                        this option disables the debugging code at boot.
 640
 641        dma_debug_entries=<number>
 642                        This option allows to tune the number of preallocated
 643                        entries for DMA-API debugging code. One entry is
 644                        required per DMA-API allocation. Use this if the
 645                        DMA-API debugging code disables itself because the
 646                        architectural default is too low.
 647
 648        dma_debug_driver=<driver_name>
 649                        With this option the DMA-API debugging driver
 650                        filter feature can be enabled at boot time. Just
 651                        pass the driver to filter for as the parameter.
 652                        The filter can be disabled or changed to another
 653                        driver later using sysfs.
 654
 655        dscc4.setup=    [NET]
 656
 657        dtc3181e=       [HW,SCSI]
 658
 659        dynamic_printk  Enables pr_debug()/dev_dbg() calls if
 660                        CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
 661                        These can also be switched on/off via
 662                        <debugfs>/dynamic_printk/modules
 663
 664        earlycon=       [KNL] Output early console device and options.
 665                uart[8250],io,<addr>[,options]
 666                uart[8250],mmio,<addr>[,options]
 667                        Start an early, polled-mode console on the 8250/16550
 668                        UART at the specified I/O port or MMIO address.
 669                        The options are the same as for ttyS, above.
 670
 671        earlyprintk=    [X86,SH,BLACKFIN]
 672                        earlyprintk=vga
 673                        earlyprintk=serial[,ttySn[,baudrate]]
 674                        earlyprintk=ttySn[,baudrate]
 675                        earlyprintk=dbgp[debugController#]
 676
 677                        Append ",keep" to not disable it when the real console
 678                        takes over.
 679
 680                        Only vga or serial or usb debug port at a time.
 681
 682                        Currently only ttyS0 and ttyS1 are supported.
 683
 684                        Interaction with the standard serial driver is not
 685                        very good.
 686
 687                        The VGA output is eventually overwritten by the real
 688                        console.
 689
 690        eata=           [HW,SCSI]
 691
 692        edd=            [EDD]
 693                        Format: {"off" | "on" | "skip[mbr]"}
 694
 695        eisa_irq_edge=  [PARISC,HW]
 696                        See header of drivers/parisc/eisa.c.
 697
 698        elanfreq=       [X86-32]
 699                        See comment before function elanfreq_setup() in
 700                        arch/x86/kernel/cpu/cpufreq/elanfreq.c.
 701
 702        elevator=       [IOSCHED]
 703                        Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
 704                        See Documentation/block/as-iosched.txt and
 705                        Documentation/block/deadline-iosched.txt for details.
 706
 707        elfcorehdr=     [IA64,PPC,SH,X86]
 708                        Specifies physical address of start of kernel core
 709                        image elf header. Generally kexec loader will
 710                        pass this option to capture kernel.
 711                        See Documentation/kdump/kdump.txt for details.
 712
 713        enable_mtrr_cleanup [X86]
 714                        The kernel tries to adjust MTRR layout from continuous
 715                        to discrete, to make X server driver able to add WB
 716                        entry later. This parameter enables that.
 717
 718        enable_timer_pin_1 [X86]
 719                        Enable PIN 1 of APIC timer
 720                        Can be useful to work around chipset bugs
 721                        (in particular on some ATI chipsets).
 722                        The kernel tries to set a reasonable default.
 723
 724        enforcing       [SELINUX] Set initial enforcing status.
 725                        Format: {"0" | "1"}
 726                        See security/selinux/Kconfig help text.
 727                        0 -- permissive (log only, no denials).
 728                        1 -- enforcing (deny and log).
 729                        Default value is 0.
 730                        Value can be changed at runtime via /selinux/enforce.
 731
 732        ether=          [HW,NET] Ethernet cards parameters
 733                        This option is obsoleted by the "netdev=" option, which
 734                        has equivalent usage. See its documentation for details.
 735
 736        eurwdt=         [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
 737                        Format: <io>[,<irq>]
 738
 739        failslab=
 740        fail_page_alloc=
 741        fail_make_request=[KNL]
 742                        General fault injection mechanism.
 743                        Format: <interval>,<probability>,<space>,<times>
 744                        See also /Documentation/fault-injection/.
 745
 746        fd_mcs=         [HW,SCSI]
 747                        See header of drivers/scsi/fd_mcs.c.
 748
 749        fdomain=        [HW,SCSI]
 750                        See header of drivers/scsi/fdomain.c.
 751
 752        floppy=         [HW]
 753                        See Documentation/blockdev/floppy.txt.
 754
 755        force_pal_cache_flush
 756                        [IA-64] Avoid check_sal_cache_flush which may hang on
 757                        buggy SAL_CACHE_FLUSH implementations. Using this
 758                        parameter will force ia64_sal_cache_flush to call
 759                        ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
 760
 761        ftrace=[tracer]
 762                        [FTRACE] will set and start the specified tracer
 763                        as early as possible in order to facilitate early
 764                        boot debugging.
 765
 766        ftrace_dump_on_oops
 767                        [FTRACE] will dump the trace buffers on oops.
 768
 769        ftrace_filter=[function-list]
 770                        [FTRACE] Limit the functions traced by the function
 771                        tracer at boot up. function-list is a comma separated
 772                        list of functions. This list can be changed at run
 773                        time by the set_ftrace_filter file in the debugfs
 774                        tracing directory. 
 775
 776        ftrace_notrace=[function-list]
 777                        [FTRACE] Do not trace the functions specified in
 778                        function-list. This list can be changed at run time
 779                        by the set_ftrace_notrace file in the debugfs
 780                        tracing directory.
 781
 782        gamecon.map[2|3]=
 783                        [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 784                        support via parallel port (up to 5 devices per port)
 785                        Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
 786                        See also Documentation/input/joystick-parport.txt
 787
 788        gamma=          [HW,DRM]
 789
 790        gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
 791                        Format: off | on
 792                        default: on
 793
 794        gcov_persist=   [GCOV] When non-zero (default), profiling data for
 795                        kernel modules is saved and remains accessible via
 796                        debugfs, even when the module is unloaded/reloaded.
 797                        When zero, profiling data is discarded and associated
 798                        debugfs files are removed at module unload time.
 799
 800        gdth=           [HW,SCSI]
 801                        See header of drivers/scsi/gdth.c.
 802
 803        gpt             [EFI] Forces disk with valid GPT signature but
 804                        invalid Protective MBR to be treated as GPT.
 805
 806        gvp11=          [HW,SCSI]
 807
 808        hashdist=       [KNL,NUMA] Large hashes allocated during boot
 809                        are distributed across NUMA nodes.  Defaults on
 810                        for 64bit NUMA, off otherwise.
 811                        Format: 0 | 1 (for off | on)
 812
 813        hcl=            [IA-64] SGI's Hardware Graph compatibility layer
 814
 815        hd=             [EIDE] (E)IDE hard drive subsystem geometry
 816                        Format: <cyl>,<head>,<sect>
 817
 818        highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
 819                        size of <nn>. This works even on boxes that have no
 820                        highmem otherwise. This also works to reduce highmem
 821                        size on bigger boxes.
 822
 823        highres=        [KNL] Enable/disable high resolution timer mode.
 824                        Valid parameters: "on", "off"
 825                        Default: "on"
 826
 827        hisax=          [HW,ISDN]
 828                        See Documentation/isdn/README.HiSax.
 829
 830        hlt             [BUGS=ARM,SH]
 831
 832        hpet=           [X86-32,HPET] option to control HPET usage
 833                        Format: { enable (default) | disable | force |
 834                                verbose }
 835                        disable: disable HPET and use PIT instead
 836                        force: allow force enabled of undocumented chips (ICH4,
 837                                VIA, nVidia)
 838                        verbose: show contents of HPET registers during setup
 839
 840        hugepages=      [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
 841        hugepagesz=     [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
 842                        On x86-64 and powerpc, this option can be specified
 843                        multiple times interleaved with hugepages= to reserve
 844                        huge pages of different sizes. Valid pages sizes on
 845                        x86-64 are 2M (when the CPU supports "pse") and 1G
 846                        (when the CPU supports the "pdpe1gb" cpuinfo flag)
 847                        Note that 1GB pages can only be allocated at boot time
 848                        using hugepages= and not freed afterwards.
 849
 850        hvc_iucv=       [S390] Number of z/VM IUCV hypervisor console (HVC)
 851                               terminal devices. Valid values: 0..8
 852        hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
 853                               If specified, z/VM IUCV HVC accepts connections
 854                               from listed z/VM user IDs only.
 855
 856        i2c_bus=        [HW] Override the default board specific I2C bus speed
 857                             or register an additional I2C bus that is not
 858                             registered from board initialization code.
 859                             Format:
 860                             <bus_id>,<clkrate>
 861
 862        i8042.debug     [HW] Toggle i8042 debug mode
 863        i8042.direct    [HW] Put keyboard port into non-translated mode
 864        i8042.dumbkbd   [HW] Pretend that controller can only read data from
 865                             keyboard and cannot control its state
 866                             (Don't attempt to blink the leds)
 867        i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
 868        i8042.nokbd     [HW] Don't check/create keyboard port
 869        i8042.noloop    [HW] Disable the AUX Loopback command while probing
 870                             for the AUX port
 871        i8042.nomux     [HW] Don't check presence of an active multiplexing
 872                             controller
 873        i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
 874                             controllers
 875        i8042.panicblink=
 876                        [HW] Frequency with which keyboard LEDs should blink
 877                             when kernel panics (default is 0.5 sec)
 878        i8042.reset     [HW] Reset the controller during init and cleanup
 879        i8042.unlock    [HW] Unlock (ignore) the keylock
 880
 881        i810=           [HW,DRM]
 882
 883        i8k.ignore_dmi  [HW] Continue probing hardware even if DMI data
 884                        indicates that the driver is running on unsupported
 885                        hardware.
 886        i8k.force       [HW] Activate i8k driver even if SMM BIOS signature
 887                        does not match list of supported models.
 888        i8k.power_status
 889                        [HW] Report power status in /proc/i8k
 890                        (disabled by default)
 891        i8k.restricted  [HW] Allow controlling fans only if SYS_ADMIN
 892                        capability is set.
 893
 894        ibmmcascsi=     [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
 895                        See Documentation/mca.txt.
 896
 897        icn=            [HW,ISDN]
 898                        Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
 899
 900        ide-core.nodma= [HW] (E)IDE subsystem
 901                        Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
 902                        .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
 903                        .cdrom .chs .ignore_cable are additional options
 904                        See Documentation/ide/ide.txt.
 905
 906        ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
 907                        Claim all unknown PCI IDE storage controllers.
 908
 909        idle=           [X86]
 910                        Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
 911                        Poll forces a polling idle loop that can slightly
 912                        improve the performance of waking up a idle CPU, but
 913                        will use a lot of power and make the system run hot.
 914                        Not recommended.
 915                        idle=mwait: On systems which support MONITOR/MWAIT but
 916                        the kernel chose to not use it because it doesn't save
 917                        as much power as a normal idle loop, use the
 918                        MONITOR/MWAIT idle loop anyways. Performance should be
 919                        the same as idle=poll.
 920                        idle=halt: Halt is forced to be used for CPU idle.
 921                        In such case C2/C3 won't be used again.
 922                        idle=nomwait: Disable mwait for CPU C-states
 923
 924        ignore_loglevel [KNL]
 925                        Ignore loglevel setting - this will print /all/
 926                        kernel messages to the console. Useful for debugging.
 927
 928        ihash_entries=  [KNL]
 929                        Set number of hash buckets for inode cache.
 930
 931        ima_audit=      [IMA]
 932                        Format: { "0" | "1" }
 933                        0 -- integrity auditing messages. (Default)
 934                        1 -- enable informational integrity auditing messages.
 935
 936        ima_hash=       [IMA]
 937                        Format: { "sha1" | "md5" }
 938                        default: "sha1"
 939
 940        ima_tcb         [IMA]
 941                        Load a policy which meets the needs of the Trusted
 942                        Computing Base.  This means IMA will measure all
 943                        programs exec'd, files mmap'd for exec, and all files
 944                        opened for read by uid=0.
 945
 946        in2000=         [HW,SCSI]
 947                        See header of drivers/scsi/in2000.c.
 948
 949        init=           [KNL]
 950                        Format: <full_path>
 951                        Run specified binary instead of /sbin/init as init
 952                        process.
 953
 954        initcall_debug  [KNL] Trace initcalls as they are executed.  Useful
 955                        for working out where the kernel is dying during
 956                        startup.
 957
 958        initrd=         [BOOT] Specify the location of the initial ramdisk
 959
 960        inport.irq=     [HW] Inport (ATI XL and Microsoft) busmouse driver
 961                        Format: <irq>
 962
 963        intel_iommu=    [DMAR] Intel IOMMU driver (DMAR) option
 964                on
 965                        Enable intel iommu driver.
 966                off
 967                        Disable intel iommu driver.
 968                igfx_off [Default Off]
 969                        By default, gfx is mapped as normal device. If a gfx
 970                        device has a dedicated DMAR unit, the DMAR unit is
 971                        bypassed by not enabling DMAR with this option. In
 972                        this case, gfx device will use physical address for
 973                        DMA.
 974                forcedac [x86_64]
 975                        With this option iommu will not optimize to look
 976                        for io virtual address below 32 bit forcing dual
 977                        address cycle on pci bus for cards supporting greater
 978                        than 32 bit addressing. The default is to look
 979                        for translation below 32 bit and if not available
 980                        then look in the higher range.
 981                strict [Default Off]
 982                        With this option on every unmap_single operation will
 983                        result in a hardware IOTLB flush operation as opposed
 984                        to batching them for performance.
 985
 986        inttest=        [IA64]
 987
 988        iomem=          Disable strict checking of access to MMIO memory
 989                strict  regions from userspace.
 990                relaxed
 991
 992        iommu=          [x86]
 993                off
 994                force
 995                noforce
 996                biomerge
 997                panic
 998                nopanic
 999                merge
1000                nomerge
1001                forcesac
1002                soft
1003                pt      [x86, IA64]
1004
1005        io7=            [HW] IO7 for Marvel based alpha systems
1006                        See comment before marvel_specify_io7 in
1007                        arch/alpha/kernel/core_marvel.c.
1008
1009        io_delay=       [X86] I/O delay method
1010                0x80
1011                        Standard port 0x80 based delay
1012                0xed
1013                        Alternate port 0xed based delay (needed on some systems)
1014                udelay
1015                        Simple two microseconds delay
1016                none
1017                        No delay
1018
1019        ip=             [IP_PNP]
1020                        See Documentation/filesystems/nfsroot.txt.
1021
1022        ip2=            [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1023                        See comment before ip2_setup() in
1024                        drivers/char/ip2/ip2base.c.
1025
1026        ips=            [HW,SCSI] Adaptec / IBM ServeRAID controller
1027                        See header of drivers/scsi/ips.c.
1028
1029        irqfixup        [HW]
1030                        When an interrupt is not handled search all handlers
1031                        for it. Intended to get systems with badly broken
1032                        firmware running.
1033
1034        irqpoll         [HW]
1035                        When an interrupt is not handled search all handlers
1036                        for it. Also check all handlers each timer
1037                        interrupt. Intended to get systems with badly broken
1038                        firmware running.
1039
1040        isapnp=         [ISAPNP]
1041                        Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1042
1043        isolcpus=       [KNL,SMP] Isolate CPUs from the general scheduler.
1044                        Format:
1045                        <cpu number>,...,<cpu number>
1046                        or
1047                        <cpu number>-<cpu number>
1048                        (must be a positive range in ascending order)
1049                        or a mixture
1050                        <cpu number>,...,<cpu number>-<cpu number>
1051
1052                        This option can be used to specify one or more CPUs
1053                        to isolate from the general SMP balancing and scheduling
1054                        algorithms. You can move a process onto or off an
1055                        "isolated" CPU via the CPU affinity syscalls or cpuset.
1056                        <cpu number> begins at 0 and the maximum value is
1057                        "number of CPUs in system - 1".
1058
1059                        This option is the preferred way to isolate CPUs. The
1060                        alternative -- manually setting the CPU mask of all
1061                        tasks in the system -- can cause problems and
1062                        suboptimal load balancer performance.
1063
1064        iucv=           [HW,NET]
1065
1066        js=             [HW,JOY] Analog joystick
1067                        See Documentation/input/joystick.txt.
1068
1069        keepinitrd      [HW,ARM]
1070
1071        kernelcore=nn[KMG]      [KNL,X86,IA-64,PPC] This parameter
1072                        specifies the amount of memory usable by the kernel
1073                        for non-movable allocations.  The requested amount is
1074                        spread evenly throughout all nodes in the system. The
1075                        remaining memory in each node is used for Movable
1076                        pages. In the event, a node is too small to have both
1077                        kernelcore and Movable pages, kernelcore pages will
1078                        take priority and other nodes will have a larger number
1079                        of kernelcore pages.  The Movable zone is used for the
1080                        allocation of pages that may be reclaimed or moved
1081                        by the page migration subsystem.  This means that
1082                        HugeTLB pages may not be allocated from this zone.
1083                        Note that allocations like PTEs-from-HighMem still
1084                        use the HighMem zone if it exists, and the Normal
1085                        zone if it does not.
1086
1087        kgdboc=         [HW] kgdb over consoles.
1088                        Requires a tty driver that supports console polling.
1089                        (only serial supported for now)
1090                        Format: <serial_device>[,baud]
1091
1092        kmac=           [MIPS] korina ethernet MAC address.
1093                        Configure the RouterBoard 532 series on-chip
1094                        Ethernet adapter MAC address.
1095
1096        kmemleak=       [KNL] Boot-time kmemleak enable/disable
1097                        Valid arguments: on, off
1098                        Default: on
1099
1100        kstack=N        [X86] Print N words from the kernel stack
1101                        in oops dumps.
1102
1103        kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1104                        Default is 0 (don't ignore, but inject #GP)
1105
1106        kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1107                        Default is 1 (enabled)
1108
1109        kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1110                        Default is 0 (off)
1111
1112        kvm-amd.npt=    [KVM,AMD] Disable nested paging (virtualized MMU)
1113                        for all guests.
1114                        Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1115
1116        kvm-intel.bypass_guest_pf=
1117                        [KVM,Intel] Disables bypassing of guest page faults
1118                        on Intel chips. Default is 1 (enabled)
1119
1120        kvm-intel.ept=  [KVM,Intel] Disable extended page tables
1121                        (virtualized MMU) support on capable Intel chips.
1122                        Default is 1 (enabled)
1123
1124        kvm-intel.emulate_invalid_guest_state=
1125                        [KVM,Intel] Enable emulation of invalid guest states
1126                        Default is 0 (disabled)
1127
1128        kvm-intel.flexpriority=
1129                        [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1130                        Default is 1 (enabled)
1131
1132        kvm-intel.unrestricted_guest=
1133                        [KVM,Intel] Disable unrestricted guest feature
1134                        (virtualized real and unpaged mode) on capable
1135                        Intel chips. Default is 1 (enabled)
1136
1137        kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1138                        feature (tagged TLBs) on capable Intel chips.
1139                        Default is 1 (enabled)
1140
1141        l2cr=           [PPC]
1142
1143        l3cr=           [PPC]
1144
1145        lapic           [X86-32,APIC] Enable the local APIC even if BIOS
1146                        disabled it.
1147
1148        lapic_timer_c2_ok       [X86,APIC] trust the local apic timer
1149                        in C2 power state.
1150
1151        libata.dma=     [LIBATA] DMA control
1152                        libata.dma=0      Disable all PATA and SATA DMA
1153                        libata.dma=1      PATA and SATA Disk DMA only
1154                        libata.dma=2      ATAPI (CDROM) DMA only
1155                        libata.dma=4      Compact Flash DMA only 
1156                        Combinations also work, so libata.dma=3 enables DMA
1157                        for disks and CDROMs, but not CFs.
1158        
1159        libata.ignore_hpa=      [LIBATA] Ignore HPA limit
1160                        libata.ignore_hpa=0       keep BIOS limits (default)
1161                        libata.ignore_hpa=1       ignore limits, using full disk
1162
1163        libata.noacpi   [LIBATA] Disables use of ACPI in libata suspend/resume
1164                        when set.
1165                        Format: <int>
1166
1167        libata.force=   [LIBATA] Force configurations.  The format is comma
1168                        separated list of "[ID:]VAL" where ID is
1169                        PORT[:DEVICE].  PORT and DEVICE are decimal numbers
1170                        matching port, link or device.  Basically, it matches
1171                        the ATA ID string printed on console by libata.  If
1172                        the whole ID part is omitted, the last PORT and DEVICE
1173                        values are used.  If ID hasn't been specified yet, the
1174                        configuration applies to all ports, links and devices.
1175
1176                        If only DEVICE is omitted, the parameter applies to
1177                        the port and all links and devices behind it.  DEVICE
1178                        number of 0 either selects the first device or the
1179                        first fan-out link behind PMP device.  It does not
1180                        select the host link.  DEVICE number of 15 selects the
1181                        host link and device attached to it.
1182
1183                        The VAL specifies the configuration to force.  As long
1184                        as there's no ambiguity shortcut notation is allowed.
1185                        For example, both 1.5 and 1.5G would work for 1.5Gbps.
1186                        The following configurations can be forced.
1187
1188                        * Cable type: 40c, 80c, short40c, unk, ign or sata.
1189                          Any ID with matching PORT is used.
1190
1191                        * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1192
1193                        * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1194                          udma[/][16,25,33,44,66,100,133] notation is also
1195                          allowed.
1196
1197                        * [no]ncq: Turn on or off NCQ.
1198
1199                        * nohrst, nosrst, norst: suppress hard, soft
1200                          and both resets.
1201
1202                        If there are multiple matching configurations changing
1203                        the same attribute, the last one is used.
1204
1205        lmb=debug       [KNL] Enable lmb debug messages.
1206
1207        load_ramdisk=   [RAM] List of ramdisks to load from floppy
1208                        See Documentation/blockdev/ramdisk.txt.
1209
1210        lockd.nlm_grace_period=P  [NFS] Assign grace period.
1211                        Format: <integer>
1212
1213        lockd.nlm_tcpport=N     [NFS] Assign TCP port.
1214                        Format: <integer>
1215
1216        lockd.nlm_timeout=T     [NFS] Assign timeout value.
1217                        Format: <integer>
1218
1219        lockd.nlm_udpport=M     [NFS] Assign UDP port.
1220                        Format: <integer>
1221
1222        logibm.irq=     [HW,MOUSE] Logitech Bus Mouse Driver
1223                        Format: <irq>
1224
1225        loglevel=       All Kernel Messages with a loglevel smaller than the
1226                        console loglevel will be printed to the console. It can
1227                        also be changed with klogd or other programs. The
1228                        loglevels are defined as follows:
1229
1230                        0 (KERN_EMERG)          system is unusable
1231                        1 (KERN_ALERT)          action must be taken immediately
1232                        2 (KERN_CRIT)           critical conditions
1233                        3 (KERN_ERR)            error conditions
1234                        4 (KERN_WARNING)        warning conditions
1235                        5 (KERN_NOTICE)         normal but significant condition
1236                        6 (KERN_INFO)           informational
1237                        7 (KERN_DEBUG)          debug-level messages
1238
1239        log_buf_len=n   Sets the size of the printk ring buffer, in bytes.
1240                        Format: { n | nk | nM }
1241                        n must be a power of two.  The default size
1242                        is set in the kernel config file.
1243
1244        logo.nologo     [FB] Disables display of the built-in Linux logo.
1245                        This may be used to provide more screen space for
1246                        kernel log messages and is useful when debugging
1247                        kernel boot problems.
1248
1249        lp=0            [LP]    Specify parallel ports to use, e.g,
1250        lp=port[,port...]       lp=none,parport0 (lp0 not configured, lp1 uses
1251        lp=reset                first parallel port). 'lp=0' disables the
1252        lp=auto                 printer driver. 'lp=reset' (which can be
1253                                specified in addition to the ports) causes
1254                                attached printers to be reset. Using
1255                                lp=port1,port2,... specifies the parallel ports
1256                                to associate lp devices with, starting with
1257                                lp0. A port specification may be 'none' to skip
1258                                that lp device, or a parport name such as
1259                                'parport0'. Specifying 'lp=auto' instead of a
1260                                port specification list means that device IDs
1261                                from each port should be examined, to see if
1262                                an IEEE 1284-compliant printer is attached; if
1263                                so, the driver will manage that printer.
1264                                See also header of drivers/char/lp.c.
1265
1266        lpj=n           [KNL]
1267                        Sets loops_per_jiffy to given constant, thus avoiding
1268                        time-consuming boot-time autodetection (up to 250 ms per
1269                        CPU). 0 enables autodetection (default). To determine
1270                        the correct value for your kernel, boot with normal
1271                        autodetection and see what value is printed. Note that
1272                        on SMP systems the preset will be applied to all CPUs,
1273                        which is likely to cause problems if your CPUs need
1274                        significantly divergent settings. An incorrect value
1275                        will cause delays in the kernel to be wrong, leading to
1276                        unpredictable I/O errors and other breakage. Although
1277                        unlikely, in the extreme case this might damage your
1278                        hardware.
1279
1280        ltpc=           [NET]
1281                        Format: <io>,<irq>,<dma>
1282
1283        mac5380=        [HW,SCSI] Format:
1284                        <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1285
1286        machvec=        [IA64] Force the use of a particular machine-vector
1287                        (machvec) in a generic kernel.
1288                        Example: machvec=hpzx1_swiotlb
1289
1290        machtype=       [Loongson] Share the same kernel image file between different
1291                         yeeloong laptop.
1292                        Example: machtype=lemote-yeeloong-2f-7inch
1293
1294        max_addr=nn[KMG]        [KNL,BOOT,ia64] All physical memory greater
1295                        than or equal to this physical address is ignored.
1296
1297        maxcpus=        [SMP] Maximum number of processors that an SMP kernel
1298                        should make use of.  maxcpus=n : n >= 0 limits the
1299                        kernel to using 'n' processors.  n=0 is a special case,
1300                        it is equivalent to "nosmp", which also disables
1301                        the IO APIC.
1302
1303        max_loop=       [LOOP] Maximum number of loopback devices that can
1304                        be mounted
1305                        Format: <1-256>
1306
1307        max_luns=       [SCSI] Maximum number of LUNs to probe.
1308                        Should be between 1 and 2^32-1.
1309
1310        max_report_luns=
1311                        [SCSI] Maximum number of LUNs received.
1312                        Should be between 1 and 16384.
1313
1314        mcatest=        [IA-64]
1315
1316        mce             [X86-32] Machine Check Exception
1317
1318        mce=option      [X86-64] See Documentation/x86/x86_64/boot-options.txt
1319
1320        md=             [HW] RAID subsystems devices and level
1321                        See Documentation/md.txt.
1322
1323        mdacon=         [MDA]
1324                        Format: <first>,<last>
1325                        Specifies range of consoles to be captured by the MDA.
1326
1327        mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
1328                        Amount of memory to be used when the kernel is not able
1329                        to see the whole system memory or for test.
1330                        [X86-32] Use together with memmap= to avoid physical
1331                        address space collisions. Without memmap= PCI devices
1332                        could be placed at addresses belonging to unused RAM.
1333
1334        mem=nopentium   [BUGS=X86-32] Disable usage of 4MB pages for kernel
1335                        memory.
1336
1337        memchunk=nn[KMG]
1338                        [KNL,SH] Allow user to override the default size for
1339                        per-device physically contiguous DMA buffers.
1340
1341        memmap=exactmap [KNL,X86] Enable setting of an exact
1342                        E820 memory map, as specified by the user.
1343                        Such memmap=exactmap lines can be constructed based on
1344                        BIOS output or other requirements. See the memmap=nn@ss
1345                        option description.
1346
1347        memmap=nn[KMG]@ss[KMG]
1348                        [KNL] Force usage of a specific region of memory
1349                        Region of memory to be used, from ss to ss+nn.
1350
1351        memmap=nn[KMG]#ss[KMG]
1352                        [KNL,ACPI] Mark specific memory as ACPI data.
1353                        Region of memory to be used, from ss to ss+nn.
1354
1355        memmap=nn[KMG]$ss[KMG]
1356                        [KNL,ACPI] Mark specific memory as reserved.
1357                        Region of memory to be used, from ss to ss+nn.
1358                        Example: Exclude memory from 0x18690000-0x1869ffff
1359                                 memmap=64K$0x18690000
1360                                 or
1361                                 memmap=0x10000$0x18690000
1362
1363        memory_corruption_check=0/1 [X86]
1364                        Some BIOSes seem to corrupt the first 64k of
1365                        memory when doing things like suspend/resume.
1366                        Setting this option will scan the memory
1367                        looking for corruption.  Enabling this will
1368                        both detect corruption and prevent the kernel
1369                        from using the memory being corrupted.
1370                        However, its intended as a diagnostic tool; if
1371                        repeatable BIOS-originated corruption always
1372                        affects the same memory, you can use memmap=
1373                        to prevent the kernel from using that memory.
1374
1375        memory_corruption_check_size=size [X86]
1376                        By default it checks for corruption in the low
1377                        64k, making this memory unavailable for normal
1378                        use.  Use this parameter to scan for
1379                        corruption in more or less memory.
1380
1381        memory_corruption_check_period=seconds [X86]
1382                        By default it checks for corruption every 60
1383                        seconds.  Use this parameter to check at some
1384                        other rate.  0 disables periodic checking.
1385
1386        memtest=        [KNL,X86] Enable memtest
1387                        Format: <integer>
1388                        default : 0 <disable>
1389                        Specifies the number of memtest passes to be
1390                        performed. Each pass selects another test
1391                        pattern from a given set of patterns. Memtest
1392                        fills the memory with this pattern, validates
1393                        memory contents and reserves bad memory
1394                        regions that are detected.
1395
1396        meye.*=         [HW] Set MotionEye Camera parameters
1397                        See Documentation/video4linux/meye.txt.
1398
1399        mfgpt_irq=      [IA-32] Specify the IRQ to use for the
1400                        Multi-Function General Purpose Timers on AMD Geode
1401                        platforms.
1402
1403        mfgptfix        [X86-32] Fix MFGPT timers on AMD Geode platforms when
1404                        the BIOS has incorrectly applied a workaround. TinyBIOS
1405                        version 0.98 is known to be affected, 0.99 fixes the
1406                        problem by letting the user disable the workaround.
1407
1408        mga=            [HW,DRM]
1409
1410        min_addr=nn[KMG]        [KNL,BOOT,ia64] All physical memory below this
1411                        physical address is ignored.
1412
1413        mini2440=       [ARM,HW,KNL]
1414                        Format:[0..2][b][c][t]
1415                        Default: "0tb"
1416                        MINI2440 configuration specification:
1417                        0 - The attached screen is the 3.5" TFT
1418                        1 - The attached screen is the 7" TFT
1419                        2 - The VGA Shield is attached (1024x768)
1420                        Leaving out the screen size parameter will not load
1421                        the TFT driver, and the framebuffer will be left
1422                        unconfigured.
1423                        b - Enable backlight. The TFT backlight pin will be
1424                        linked to the kernel VESA blanking code and a GPIO
1425                        LED. This parameter is not necessary when using the
1426                        VGA shield.
1427                        c - Enable the s3c camera interface.
1428                        t - Reserved for enabling touchscreen support. The
1429                        touchscreen support is not enabled in the mainstream
1430                        kernel as of 2.6.30, a preliminary port can be found
1431                        in the "bleeding edge" mini2440 support kernel at
1432                        http://repo.or.cz/w/linux-2.6/mini2440.git
1433
1434        mminit_loglevel=
1435                        [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1436                        parameter allows control of the logging verbosity for
1437                        the additional memory initialisation checks. A value
1438                        of 0 disables mminit logging and a level of 4 will
1439                        log everything. Information is printed at KERN_DEBUG
1440                        so loglevel=8 may also need to be specified.
1441
1442        mousedev.tap_time=
1443                        [MOUSE] Maximum time between finger touching and
1444                        leaving touchpad surface for touch to be considered
1445                        a tap and be reported as a left button click (for
1446                        touchpads working in absolute mode only).
1447                        Format: <msecs>
1448        mousedev.xres=  [MOUSE] Horizontal screen resolution, used for devices
1449                        reporting absolute coordinates, such as tablets
1450        mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
1451                        reporting absolute coordinates, such as tablets
1452
1453        movablecore=nn[KMG]     [KNL,X86,IA-64,PPC] This parameter
1454                        is similar to kernelcore except it specifies the
1455                        amount of memory used for migratable allocations.
1456                        If both kernelcore and movablecore is specified,
1457                        then kernelcore will be at *least* the specified
1458                        value but may be more. If movablecore on its own
1459                        is specified, the administrator must be careful
1460                        that the amount of memory usable for all allocations
1461                        is not too small.
1462
1463        mpu401=         [HW,OSS]
1464                        Format: <io>,<irq>
1465
1466        MTD_Partition=  [MTD]
1467                        Format: <name>,<region-number>,<size>,<offset>
1468
1469        MTD_Region=     [MTD] Format:
1470                        <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1471
1472        mtdparts=       [MTD]
1473                        See drivers/mtd/cmdlinepart.c.
1474
1475        onenand.bdry=   [HW,MTD] Flex-OneNAND Boundary Configuration
1476
1477                        Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1478
1479                        boundary - index of last SLC block on Flex-OneNAND.
1480                                   The remaining blocks are configured as MLC blocks.
1481                        lock     - Configure if Flex-OneNAND boundary should be locked.
1482                                   Once locked, the boundary cannot be changed.
1483                                   1 indicates lock status, 0 indicates unlock status.
1484
1485        mtdset=         [ARM]
1486                        ARM/S3C2412 JIVE boot control
1487
1488                        See arch/arm/mach-s3c2412/mach-jive.c
1489
1490        mtouchusb.raw_coordinates=
1491                        [HW] Make the MicroTouch USB driver use raw coordinates
1492                        ('y', default) or cooked coordinates ('n')
1493
1494        mtrr_chunk_size=nn[KMG] [X86]
1495                        used for mtrr cleanup. It is largest continuous chunk
1496                        that could hold holes aka. UC entries.
1497
1498        mtrr_gran_size=nn[KMG] [X86]
1499                        Used for mtrr cleanup. It is granularity of mtrr block.
1500                        Default is 1.
1501                        Large value could prevent small alignment from
1502                        using up MTRRs.
1503
1504        mtrr_spare_reg_nr=n [X86]
1505                        Format: <integer>
1506                        Range: 0,7 : spare reg number
1507                        Default : 1
1508                        Used for mtrr cleanup. It is spare mtrr entries number.
1509                        Set to 2 or more if your graphical card needs more.
1510
1511        n2=             [NET] SDL Inc. RISCom/N2 synchronous serial card
1512
1513        NCR_D700=       [HW,SCSI]
1514                        See header of drivers/scsi/NCR_D700.c.
1515
1516        ncr5380=        [HW,SCSI]
1517
1518        ncr53c400=      [HW,SCSI]
1519
1520        ncr53c400a=     [HW,SCSI]
1521
1522        ncr53c406a=     [HW,SCSI]
1523
1524        ncr53c8xx=      [HW,SCSI]
1525
1526        netdev=         [NET] Network devices parameters
1527                        Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1528                        Note that mem_start is often overloaded to mean
1529                        something different and driver-specific.
1530                        This usage is only documented in each driver source
1531                        file if at all.
1532
1533        nf_conntrack.acct=
1534                        [NETFILTER] Enable connection tracking flow accounting
1535                        0 to disable accounting
1536                        1 to enable accounting
1537                        Default value depends on CONFIG_NF_CT_ACCT that is
1538                        going to be removed in 2.6.29.
1539
1540        nfsaddrs=       [NFS]
1541                        See Documentation/filesystems/nfsroot.txt.
1542
1543        nfsroot=        [NFS] nfs root filesystem for disk-less boxes.
1544                        See Documentation/filesystems/nfsroot.txt.
1545
1546        nfs.callback_tcpport=
1547                        [NFS] set the TCP port on which the NFSv4 callback
1548                        channel should listen.
1549
1550        nfs.cache_getent=
1551                        [NFS] sets the pathname to the program which is used
1552                        to update the NFS client cache entries.
1553
1554        nfs.cache_getent_timeout=
1555                        [NFS] sets the timeout after which an attempt to
1556                        update a cache entry is deemed to have failed.
1557
1558        nfs.idmap_cache_timeout=
1559                        [NFS] set the maximum lifetime for idmapper cache
1560                        entries.
1561
1562        nfs.enable_ino64=
1563                        [NFS] enable 64-bit inode numbers.
1564                        If zero, the NFS client will fake up a 32-bit inode
1565                        number for the readdir() and stat() syscalls instead
1566                        of returning the full 64-bit number.
1567                        The default is to return 64-bit inode numbers.
1568
1569        nmi_debug=      [KNL,AVR32,SH] Specify one or more actions to take
1570                        when a NMI is triggered.
1571                        Format: [state][,regs][,debounce][,die]
1572
1573        nmi_watchdog=   [KNL,BUGS=X86] Debugging features for SMP kernels
1574                        Format: [panic,][num]
1575                        Valid num: 0,1,2
1576                        0 - turn nmi_watchdog off
1577                        1 - use the IO-APIC timer for the NMI watchdog
1578                        2 - use the local APIC for the NMI watchdog using
1579                        a performance counter. Note: This will use one
1580                        performance counter and the local APIC's performance
1581                        vector.
1582                        When panic is specified, panic when an NMI watchdog
1583                        timeout occurs.
1584                        This is useful when you use a panic=... timeout and
1585                        need the box quickly up again.
1586                        Instead of 1 and 2 it is possible to use the following
1587                        symbolic names: lapic and ioapic
1588                        Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1589
1590        netpoll.carrier_timeout=
1591                        [NET] Specifies amount of time (in seconds) that
1592                        netpoll should wait for a carrier. By default netpoll
1593                        waits 4 seconds.
1594
1595        no387           [BUGS=X86-32] Tells the kernel to use the 387 maths
1596                        emulation library even if a 387 maths coprocessor
1597                        is present.
1598
1599        no_console_suspend
1600                        [HW] Never suspend the console
1601                        Disable suspending of consoles during suspend and
1602                        hibernate operations.  Once disabled, debugging
1603                        messages can reach various consoles while the rest
1604                        of the system is being put to sleep (ie, while
1605                        debugging driver suspend/resume hooks).  This may
1606                        not work reliably with all consoles, but is known
1607                        to work with serial and VGA consoles.
1608
1609        noaliencache    [MM, NUMA, SLAB] Disables the allocation of alien
1610                        caches in the slab allocator.  Saves per-node memory,
1611                        but will impact performance.
1612
1613        noalign         [KNL,ARM]
1614
1615        noapic          [SMP,APIC] Tells the kernel to not make use of any
1616                        IOAPICs that may be present in the system.
1617
1618        nobats          [PPC] Do not use BATs for mapping kernel lowmem
1619                        on "Classic" PPC cores.
1620
1621        nocache         [ARM]
1622
1623        noclflush       [BUGS=X86] Don't use the CLFLUSH instruction
1624
1625        nodelayacct     [KNL] Disable per-task delay accounting
1626
1627        nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
1628
1629        nodsp           [SH] Disable hardware DSP at boot time.
1630
1631        noefi           [X86] Disable EFI runtime services support.
1632
1633        noexec          [IA-64]
1634
1635        noexec          [X86]
1636                        On X86-32 available only on PAE configured kernels.
1637                        noexec=on: enable non-executable mappings (default)
1638                        noexec=off: disable non-executable mappings
1639
1640        noexec32        [X86-64]
1641                        This affects only 32-bit executables.
1642                        noexec32=on: enable non-executable mappings (default)
1643                                read doesn't imply executable mappings
1644                        noexec32=off: disable non-executable mappings
1645                                read implies executable mappings
1646
1647        nofpu           [SH] Disable hardware FPU at boot time.
1648
1649        nofxsr          [BUGS=X86-32] Disables x86 floating point extended
1650                        register save and restore. The kernel will only save
1651                        legacy floating-point registers on task switch.
1652
1653        noxsave         [BUGS=X86] Disables x86 extended register state save
1654                        and restore using xsave. The kernel will fallback to
1655                        enabling legacy floating-point and sse state.
1656
1657        nohlt           [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1658                        wfi(ARM) instruction doesn't work correctly and not to
1659                        use it. This is also useful when using JTAG debugger.
1660
1661        no-hlt          [BUGS=X86-32] Tells the kernel that the hlt
1662                        instruction doesn't work correctly and not to
1663                        use it.
1664
1665        no_file_caps    Tells the kernel not to honor file capabilities.  The
1666                        only way then for a file to be executed with privilege
1667                        is to be setuid root or executed by root.
1668
1669        nohalt          [IA-64] Tells the kernel not to use the power saving
1670                        function PAL_HALT_LIGHT when idle. This increases
1671                        power-consumption. On the positive side, it reduces
1672                        interrupt wake-up latency, which may improve performance
1673                        in certain environments such as networked servers or
1674                        real-time systems.
1675
1676        nohz=           [KNL] Boottime enable/disable dynamic ticks
1677                        Valid arguments: on, off
1678                        Default: on
1679
1680        noiotrap        [SH] Disables trapped I/O port accesses.
1681
1682        noirqdebug      [X86-32] Disables the code which attempts to detect and
1683                        disable unhandled interrupt sources.
1684
1685        no_timer_check  [X86,APIC] Disables the code which tests for
1686                        broken timer IRQ sources.
1687
1688        noisapnp        [ISAPNP] Disables ISA PnP code.
1689
1690        noinitrd        [RAM] Tells the kernel not to load any configured
1691                        initial RAM disk.
1692
1693        nointremap      [X86-64, Intel-IOMMU] Do not enable interrupt
1694                        remapping.
1695
1696        nointroute      [IA-64]
1697
1698        nojitter        [IA64] Disables jitter checking for ITC timers.
1699
1700        nolapic         [X86-32,APIC] Do not enable or use the local APIC.
1701
1702        nolapic_timer   [X86-32,APIC] Do not use the local APIC timer.
1703
1704        noltlbs         [PPC] Do not use large page/tlb entries for kernel
1705                        lowmem mapping on PPC40x.
1706
1707        nomca           [IA-64] Disable machine check abort handling
1708
1709        nomce           [X86-32] Machine Check Exception
1710
1711        nomfgpt         [X86-32] Disable Multi-Function General Purpose
1712                        Timer usage (for AMD Geode machines).
1713
1714        norandmaps      Don't use address space randomization.  Equivalent to
1715                        echo 0 > /proc/sys/kernel/randomize_va_space
1716
1717        noreplace-paravirt      [X86-32,PV_OPS] Don't patch paravirt_ops
1718
1719        noreplace-smp   [X86-32,SMP] Don't replace SMP instructions
1720                        with UP alternatives
1721
1722        noresidual      [PPC] Don't use residual data on PReP machines.
1723
1724        noresume        [SWSUSP] Disables resume and restores original swap
1725                        space.
1726
1727        no-scroll       [VGA] Disables scrollback.
1728                        This is required for the Braillex ib80-piezo Braille
1729                        reader made by F.H. Papenmeier (Germany).
1730
1731        nosbagart       [IA-64]
1732
1733        nosep           [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1734
1735        nosmp           [SMP] Tells an SMP kernel to act as a UP kernel,
1736                        and disable the IO APIC.  legacy for "maxcpus=0".
1737
1738        nosoftlockup    [KNL] Disable the soft-lockup detector.
1739
1740        noswapaccount   [KNL] Disable accounting of swap in memory resource
1741                        controller. (See Documentation/cgroups/memory.txt)
1742
1743        nosync          [HW,M68K] Disables sync negotiation for all devices.
1744
1745        notsc           [BUGS=X86-32] Disable Time Stamp Counter
1746
1747        nousb           [USB] Disable the USB subsystem
1748
1749        nowb            [ARM]
1750
1751        nox2apic        [X86-64,APIC] Do not enable x2APIC mode.
1752
1753        nptcg=          [IA64] Override max number of concurrent global TLB
1754                        purges which is reported from either PAL_VM_SUMMARY or
1755                        SAL PALO.
1756
1757        nr_uarts=       [SERIAL] maximum number of UARTs to be registered.
1758
1759        numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1760                        one of ['zone', 'node', 'default'] can be specified
1761                        This can be set from sysctl after boot.
1762                        See Documentation/sysctl/vm.txt for details.
1763
1764        ohci1394_dma=early      [HW] enable debugging via the ohci1394 driver.
1765                        See Documentation/debugging-via-ohci1394.txt for more
1766                        info.
1767
1768        olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1769                        Rather than timing out after 20 ms if an EC
1770                        command is not properly ACKed, override the length
1771                        of the timeout.  We have interrupts disabled while
1772                        waiting for the ACK, so if this is set too high
1773                        interrupts *may* be lost!
1774
1775        opl3=           [HW,OSS]
1776                        Format: <io>
1777
1778        oprofile.timer= [HW]
1779                        Use timer interrupt instead of performance counters
1780
1781        oprofile.cpu_type=      Force an oprofile cpu type
1782                        This might be useful if you have an older oprofile
1783                        userland or if you want common events.
1784                        Format: { arch_perfmon }
1785                        arch_perfmon: [X86] Force use of architectural
1786                                perfmon on Intel CPUs instead of the
1787                                CPU specific event set.
1788
1789        osst=           [HW,SCSI] SCSI Tape Driver
1790                        Format: <buffer_size>,<write_threshold>
1791                        See also Documentation/scsi/st.txt.
1792
1793        panic=          [KNL] Kernel behaviour on panic
1794                        Format: <timeout>
1795
1796        parkbd.port=    [HW] Parallel port number the keyboard adapter is
1797                        connected to, default is 0.
1798                        Format: <parport#>
1799        parkbd.mode=    [HW] Parallel port keyboard adapter mode of operation,
1800                        0 for XT, 1 for AT (default is AT).
1801                        Format: <mode>
1802
1803        parport=        [HW,PPT] Specify parallel ports. 0 disables.
1804                        Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1805                        Use 'auto' to force the driver to use any
1806                        IRQ/DMA settings detected (the default is to
1807                        ignore detected IRQ/DMA settings because of
1808                        possible conflicts). You can specify the base
1809                        address, IRQ, and DMA settings; IRQ and DMA
1810                        should be numbers, or 'auto' (for using detected
1811                        settings on that particular port), or 'nofifo'
1812                        (to avoid using a FIFO even if it is detected).
1813                        Parallel ports are assigned in the order they
1814                        are specified on the command line, starting
1815                        with parport0.
1816
1817        parport_init_mode=      [HW,PPT]
1818                        Configure VIA parallel port to operate in
1819                        a specific mode. This is necessary on Pegasos
1820                        computer where firmware has no options for setting
1821                        up parallel port mode and sets it to spp.
1822                        Currently this function knows 686a and 8231 chips.
1823                        Format: [spp|ps2|epp|ecp|ecpepp]
1824
1825        pas2=           [HW,OSS] Format:
1826                        <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1827
1828        pas16=          [HW,SCSI]
1829                        See header of drivers/scsi/pas16.c.
1830
1831        pause_on_oops=
1832                        Halt all CPUs after the first oops has been printed for
1833                        the specified number of seconds.  This is to be used if
1834                        your oopses keep scrolling off the screen.
1835
1836        pcbit=          [HW,ISDN]
1837
1838        pcd.            [PARIDE]
1839                        See header of drivers/block/paride/pcd.c.
1840                        See also Documentation/blockdev/paride.txt.
1841
1842        pci=option[,option...]  [PCI] various PCI subsystem options:
1843                earlydump       [X86] dump PCI config space before the kernel
1844                                changes anything
1845                off             [X86] don't probe for the PCI bus
1846                bios            [X86-32] force use of PCI BIOS, don't access
1847                                the hardware directly. Use this if your machine
1848                                has a non-standard PCI host bridge.
1849                nobios          [X86-32] disallow use of PCI BIOS, only direct
1850                                hardware access methods are allowed. Use this
1851                                if you experience crashes upon bootup and you
1852                                suspect they are caused by the BIOS.
1853                conf1           [X86] Force use of PCI Configuration
1854                                Mechanism 1.
1855                conf2           [X86] Force use of PCI Configuration
1856                                Mechanism 2.
1857                noaer           [PCIE] If the PCIEAER kernel config parameter is
1858                                enabled, this kernel boot option can be used to
1859                                disable the use of PCIE advanced error reporting.
1860                nodomains       [PCI] Disable support for multiple PCI
1861                                root domains (aka PCI segments, in ACPI-speak).
1862                nommconf        [X86] Disable use of MMCONFIG for PCI
1863                                Configuration
1864                check_enable_amd_mmconf [X86] check for and enable
1865                                properly configured MMIO access to PCI
1866                                config space on AMD family 10h CPU
1867                nomsi           [MSI] If the PCI_MSI kernel config parameter is
1868                                enabled, this kernel boot option can be used to
1869                                disable the use of MSI interrupts system-wide.
1870                noioapicquirk   [APIC] Disable all boot interrupt quirks.
1871                                Safety option to keep boot IRQs enabled. This
1872                                should never be necessary.
1873                ioapicreroute   [APIC] Enable rerouting of boot IRQs to the
1874                                primary IO-APIC for bridges that cannot disable
1875                                boot IRQs. This fixes a source of spurious IRQs
1876                                when the system masks IRQs.
1877                noioapicreroute [APIC] Disable workaround that uses the
1878                                boot IRQ equivalent of an IRQ that connects to
1879                                a chipset where boot IRQs cannot be disabled.
1880                                The opposite of ioapicreroute.
1881                biosirq         [X86-32] Use PCI BIOS calls to get the interrupt
1882                                routing table. These calls are known to be buggy
1883                                on several machines and they hang the machine
1884                                when used, but on other computers it's the only
1885                                way to get the interrupt routing table. Try
1886                                this option if the kernel is unable to allocate
1887                                IRQs or discover secondary PCI buses on your
1888                                motherboard.
1889                rom             [X86] Assign address space to expansion ROMs.
1890                                Use with caution as certain devices share
1891                                address decoders between ROMs and other
1892                                resources.
1893                norom           [X86] Do not assign address space to
1894                                expansion ROMs that do not already have
1895                                BIOS assigned address ranges.
1896                irqmask=0xMMMM  [X86] Set a bit mask of IRQs allowed to be
1897                                assigned automatically to PCI devices. You can
1898                                make the kernel exclude IRQs of your ISA cards
1899                                this way.
1900                pirqaddr=0xAAAAA        [X86] Specify the physical address
1901                                of the PIRQ table (normally generated
1902                                by the BIOS) if it is outside the
1903                                F0000h-100000h range.
1904                lastbus=N       [X86] Scan all buses thru bus #N. Can be
1905                                useful if the kernel is unable to find your
1906                                secondary buses and you want to tell it
1907                                explicitly which ones they are.
1908                assign-busses   [X86] Always assign all PCI bus
1909                                numbers ourselves, overriding
1910                                whatever the firmware may have done.
1911                usepirqmask     [X86] Honor the possible IRQ mask stored
1912                                in the BIOS $PIR table. This is needed on
1913                                some systems with broken BIOSes, notably
1914                                some HP Pavilion N5400 and Omnibook XE3
1915                                notebooks. This will have no effect if ACPI
1916                                IRQ routing is enabled.
1917                noacpi          [X86] Do not use ACPI for IRQ routing
1918                                or for PCI scanning.
1919                use_crs         [X86] Use _CRS for PCI resource
1920                                allocation.
1921                routeirq        Do IRQ routing for all PCI devices.
1922                                This is normally done in pci_enable_device(),
1923                                so this option is a temporary workaround
1924                                for broken drivers that don't call it.
1925                skip_isa_align  [X86] do not align io start addr, so can
1926                                handle more pci cards
1927                firmware        [ARM] Do not re-enumerate the bus but instead
1928                                just use the configuration from the
1929                                bootloader. This is currently used on
1930                                IXP2000 systems where the bus has to be
1931                                configured a certain way for adjunct CPUs.
1932                noearly         [X86] Don't do any early type 1 scanning.
1933                                This might help on some broken boards which
1934                                machine check when some devices' config space
1935                                is read. But various workarounds are disabled
1936                                and some IOMMU drivers will not work.
1937                bfsort          Sort PCI devices into breadth-first order.
1938                                This sorting is done to get a device
1939                                order compatible with older (<= 2.4) kernels.
1940                nobfsort        Don't sort PCI devices into breadth-first order.
1941                cbiosize=nn[KMG]        The fixed amount of bus space which is
1942                                reserved for the CardBus bridge's IO window.
1943                                The default value is 256 bytes.
1944                cbmemsize=nn[KMG]       The fixed amount of bus space which is
1945                                reserved for the CardBus bridge's memory
1946                                window. The default value is 64 megabytes.
1947                resource_alignment=
1948                                Format:
1949                                [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1950                                Specifies alignment and device to reassign
1951                                aligned memory resources.
1952                                If <order of align> is not specified,
1953                                PAGE_SIZE is used as alignment.
1954                                PCI-PCI bridge can be specified, if resource
1955                                windows need to be expanded.
1956                ecrc=           Enable/disable PCIe ECRC (transaction layer
1957                                end-to-end CRC checking).
1958                                bios: Use BIOS/firmware settings. This is the
1959                                the default.
1960                                off: Turn ECRC off
1961                                on: Turn ECRC on.
1962
1963        pcie_aspm=      [PCIE] Forcibly enable or disable PCIe Active State Power
1964                        Management.
1965                off     Disable ASPM.
1966                force   Enable ASPM even on devices that claim not to support it.
1967                        WARNING: Forcing ASPM on may cause system lockups.
1968
1969        pcmv=           [HW,PCMCIA] BadgePAD 4
1970
1971        pd.             [PARIDE]
1972                        See Documentation/blockdev/paride.txt.
1973
1974        pdcchassis=     [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1975                        boot time.
1976                        Format: { 0 | 1 }
1977                        See arch/parisc/kernel/pdc_chassis.c
1978
1979        percpu_alloc=   Select which percpu first chunk allocator to use.
1980                        Currently supported values are "embed" and "page".
1981                        Archs may support subset or none of the selections.
1982                        See comments in mm/percpu.c for details on each
1983                        allocator.  This parameter is primarily for debugging
1984                        and performance comparison.
1985
1986        pf.             [PARIDE]
1987                        See Documentation/blockdev/paride.txt.
1988
1989        pg.             [PARIDE]
1990                        See Documentation/blockdev/paride.txt.
1991
1992        pirq=           [SMP,APIC] Manual mp-table setup
1993                        See Documentation/x86/i386/IO-APIC.txt.
1994
1995        plip=           [PPT,NET] Parallel port network link
1996                        Format: { parport<nr> | timid | 0 }
1997                        See also Documentation/parport.txt.
1998
1999        pmtmr=          [X86] Manual setup of pmtmr I/O Port. 
2000                        Override pmtimer IOPort with a hex value.
2001                        e.g. pmtmr=0x508
2002
2003        pnp.debug       [PNP]
2004                        Enable PNP debug messages.  This depends on the
2005                        CONFIG_PNP_DEBUG_MESSAGES option.
2006
2007        pnpacpi=        [ACPI]
2008                        { off }
2009
2010        pnpbios=        [ISAPNP]
2011                        { on | off | curr | res | no-curr | no-res }
2012
2013        pnp_reserve_irq=
2014                        [ISAPNP] Exclude IRQs for the autoconfiguration
2015
2016        pnp_reserve_dma=
2017                        [ISAPNP] Exclude DMAs for the autoconfiguration
2018
2019        pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2020                        Ranges are in pairs (I/O port base and size).
2021
2022        pnp_reserve_mem=
2023                        [ISAPNP] Exclude memory regions for the
2024                        autoconfiguration.
2025                        Ranges are in pairs (memory base and size).
2026
2027        ports=          [IP_VS_FTP] IPVS ftp helper module
2028                        Default is 21.
2029                        Up to 8 (IP_VS_APP_MAX_PORTS) ports
2030                        may be specified.
2031                        Format: <port>,<port>....
2032
2033        print-fatal-signals=
2034                        [KNL] debug: print fatal signals
2035                        print-fatal-signals=1: print segfault info to
2036                        the kernel console.
2037                        default: off.
2038
2039        printk.time=    Show timing data prefixed to each printk message line
2040                        Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
2041
2042        processor.max_cstate=   [HW,ACPI]
2043                        Limit processor to maximum C-state
2044                        max_cstate=9 overrides any DMI blacklist limit.
2045
2046        processor.nocst [HW,ACPI]
2047                        Ignore the _CST method to determine C-states,
2048                        instead using the legacy FADT method
2049
2050        profile=        [KNL] Enable kernel profiling via /proc/profile
2051                        Format: [schedule,]<number>
2052                        Param: "schedule" - profile schedule points.
2053                        Param: <number> - step/bucket size as a power of 2 for
2054                                statistical time based profiling.
2055                        Param: "sleep" - profile D-state sleeping (millisecs).
2056                                Requires CONFIG_SCHEDSTATS
2057                        Param: "kvm" - profile VM exits.
2058
2059        prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2060                        before loading.
2061                        See Documentation/blockdev/ramdisk.txt.
2062
2063        psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
2064                        probe for; one of (bare|imps|exps|lifebook|any).
2065        psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
2066                        per second.
2067        psmouse.resetafter=     [HW,MOUSE]
2068                        Try to reset the device after so many bad packets
2069                        (0 = never).
2070        psmouse.resolution=
2071                        [HW,MOUSE] Set desired mouse resolution, in dpi.
2072        psmouse.smartscroll=
2073                        [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2074                        0 = disabled, 1 = enabled (default).
2075
2076        pss=            [HW,OSS] Personal Sound System (ECHO ESC614)
2077                        Format:
2078                        <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2079
2080        pt.             [PARIDE]
2081                        See Documentation/blockdev/paride.txt.
2082
2083        pty.legacy_count=
2084                        [KNL] Number of legacy pty's. Overwrites compiled-in
2085                        default number.
2086
2087        quiet           [KNL] Disable most log messages
2088
2089        r128=           [HW,DRM]
2090
2091        raid=           [HW,RAID]
2092                        See Documentation/md.txt.
2093
2094        ramdisk_blocksize=      [RAM]
2095                        See Documentation/blockdev/ramdisk.txt.
2096
2097        ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
2098                        See Documentation/blockdev/ramdisk.txt.
2099
2100        rcupdate.blimit=        [KNL,BOOT]
2101                        Set maximum number of finished RCU callbacks to process
2102                        in one batch.
2103
2104        rcupdate.qhimark=       [KNL,BOOT]
2105                        Set threshold of queued
2106                        RCU callbacks over which batch limiting is disabled.
2107
2108        rcupdate.qlowmark=      [KNL,BOOT]
2109                        Set threshold of queued RCU callbacks below which
2110                        batch limiting is re-enabled.
2111
2112        rdinit=         [KNL]
2113                        Format: <full_path>
2114                        Run specified binary instead of /init from the ramdisk,
2115                        used for early userspace startup. See initrd.
2116
2117        reboot=         [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2118                        Format: <reboot_mode>[,<reboot_mode2>[,...]]
2119                        See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2120
2121        relax_domain_level=
2122                        [KNL, SMP] Set scheduler's default relax_domain_level.
2123                        See Documentation/cgroups/cpusets.txt.
2124
2125        reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
2126
2127        reservetop=     [X86-32]
2128                        Format: nn[KMG]
2129                        Reserves a hole at the top of the kernel virtual
2130                        address space.
2131
2132        reset_devices   [KNL] Force drivers to reset the underlying device
2133                        during initialization.
2134
2135        resume=         [SWSUSP]
2136                        Specify the partition device for software suspend
2137
2138        resume_offset=  [SWSUSP]
2139                        Specify the offset from the beginning of the partition
2140                        given by "resume=" at which the swap header is located,
2141                        in <PAGE_SIZE> units (needed only for swap files).
2142                        See  Documentation/power/swsusp-and-swap-files.txt
2143
2144        retain_initrd   [RAM] Keep initrd memory after extraction
2145
2146        rhash_entries=  [KNL,NET]
2147                        Set number of hash buckets for route cache
2148
2149        riscom8=        [HW,SERIAL]
2150                        Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2151
2152        ro              [KNL] Mount root device read-only on boot
2153
2154        root=           [KNL] Root filesystem
2155
2156        rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
2157                        mount the root filesystem
2158
2159        rootflags=      [KNL] Set root filesystem mount option string
2160
2161        rootfstype=     [KNL] Set root filesystem type
2162
2163        rootwait        [KNL] Wait (indefinitely) for root device to show up.
2164                        Useful for devices that are detected asynchronously
2165                        (e.g. USB and MMC devices).
2166
2167        root_plug.vendor_id=
2168                        [ROOTPLUG] Override the default vendor ID
2169
2170        root_plug.product_id=
2171                        [ROOTPLUG] Override the default product ID
2172
2173        root_plug.debug=
2174                        [ROOTPLUG] Enable debugging output
2175
2176        rw              [KNL] Mount root device read-write on boot
2177
2178        S               [KNL] Run init in single mode
2179
2180        sa1100ir        [NET]
2181                        See drivers/net/irda/sa1100_ir.c.
2182
2183        sbni=           [NET] Granch SBNI12 leased line adapter
2184
2185        sc1200wdt=      [HW,WDT] SC1200 WDT (watchdog) driver
2186                        Format: <io>[,<timeout>[,<isapnp>]]
2187
2188        scsi_debug_*=   [SCSI]
2189                        See drivers/scsi/scsi_debug.c.
2190
2191        scsi_default_dev_flags=
2192                        [SCSI] SCSI default device flags
2193                        Format: <integer>
2194
2195        scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2196                        Format: <vendor>:<model>:<flags>
2197                        (flags are integer value)
2198
2199        scsi_logging_level=     [SCSI] a bit mask of logging levels
2200                        See drivers/scsi/scsi_logging.h for bits.  Also
2201                        settable via sysctl at dev.scsi.logging_level
2202                        (/proc/sys/dev/scsi/logging_level).
2203                        There is also a nice 'scsi_logging_level' script in the
2204                        S390-tools package, available for download at
2205                        http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2206
2207        scsi_mod.scan=  [SCSI] sync (default) scans SCSI busses as they are
2208                        discovered.  async scans them in kernel threads,
2209                        allowing boot to proceed.  none ignores them, expecting
2210                        user space to do the scan.
2211
2212        security=       [SECURITY] Choose a security module to enable at boot.
2213                        If this boot parameter is not specified, only the first
2214                        security module asking for security registration will be
2215                        loaded. An invalid security module name will be treated
2216                        as if no module has been chosen.
2217
2218        selinux=        [SELINUX] Disable or enable SELinux at boot time.
2219                        Format: { "0" | "1" }
2220                        See security/selinux/Kconfig help text.
2221                        0 -- disable.
2222                        1 -- enable.
2223                        Default value is set via kernel config option.
2224                        If enabled at boot time, /selinux/disable can be used
2225                        later to disable prior to initial policy load.
2226
2227        serialnumber    [BUGS=X86-32]
2228
2229        shapers=        [NET]
2230                        Maximal number of shapers.
2231
2232        show_msr=       [x86] show boot-time MSR settings
2233                        Format: { <integer> }
2234                        Show boot-time (BIOS-initialized) MSR settings.
2235                        The parameter means the number of CPUs to show,
2236                        for example 1 means boot CPU only.
2237
2238        sim710=         [SCSI,HW]
2239                        See header of drivers/scsi/sim710.c.
2240
2241        simeth=         [IA-64]
2242        simscsi=
2243
2244        slram=          [HW,MTD]
2245
2246        slub_debug[=options[,slabs]]    [MM, SLUB]
2247                        Enabling slub_debug allows one to determine the
2248                        culprit if slab objects become corrupted. Enabling
2249                        slub_debug can create guard zones around objects and
2250                        may poison objects when not in use. Also tracks the
2251                        last alloc / free. For more information see
2252                        Documentation/vm/slub.txt.
2253
2254        slub_max_order= [MM, SLUB]
2255                        Determines the maximum allowed order for slabs.
2256                        A high setting may cause OOMs due to memory
2257                        fragmentation. For more information see
2258                        Documentation/vm/slub.txt.
2259
2260        slub_min_objects=       [MM, SLUB]
2261                        The minimum number of objects per slab. SLUB will
2262                        increase the slab order up to slub_max_order to
2263                        generate a sufficiently large slab able to contain
2264                        the number of objects indicated. The higher the number
2265                        of objects the smaller the overhead of tracking slabs
2266                        and the less frequently locks need to be acquired.
2267                        For more information see Documentation/vm/slub.txt.
2268
2269        slub_min_order= [MM, SLUB]
2270                        Determines the mininum page order for slabs. Must be
2271                        lower than slub_max_order.
2272                        For more information see Documentation/vm/slub.txt.
2273
2274        slub_nomerge    [MM, SLUB]
2275                        Disable merging of slabs with similar size. May be
2276                        necessary if there is some reason to distinguish
2277                        allocs to different slabs. Debug options disable
2278                        merging on their own.
2279                        For more information see Documentation/vm/slub.txt.
2280
2281        smart2=         [HW]
2282                        Format: <io1>[,<io2>[,...,<io8>]]
2283
2284        smp-alt-once    [X86-32,SMP] On a hotplug CPU system, only
2285                        attempt to substitute SMP alternatives once at boot.
2286
2287        smsc-ircc2.nopnp        [HW] Don't use PNP to discover SMC devices
2288        smsc-ircc2.ircc_cfg=    [HW] Device configuration I/O port
2289        smsc-ircc2.ircc_sir=    [HW] SIR base I/O port
2290        smsc-ircc2.ircc_fir=    [HW] FIR base I/O port
2291        smsc-ircc2.ircc_irq=    [HW] IRQ line
2292        smsc-ircc2.ircc_dma=    [HW] DMA channel
2293        smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2294                                0: Toshiba Satellite 1800 (GP data pin select)
2295                                1: Fast pin select (default)
2296                                2: ATC IRMode
2297
2298        snd-ad1816a=    [HW,ALSA]
2299
2300        snd-ad1848=     [HW,ALSA]
2301
2302        snd-ali5451=    [HW,ALSA]
2303
2304        snd-als100=     [HW,ALSA]
2305
2306        snd-als4000=    [HW,ALSA]
2307
2308        snd-azt2320=    [HW,ALSA]
2309
2310        snd-cmi8330=    [HW,ALSA]
2311
2312        snd-cmipci=     [HW,ALSA]
2313
2314        snd-cs4231=     [HW,ALSA]
2315
2316        snd-cs4232=     [HW,ALSA]
2317
2318        snd-cs4236=     [HW,ALSA]
2319
2320        snd-cs4281=     [HW,ALSA]
2321
2322        snd-cs46xx=     [HW,ALSA]
2323
2324        snd-dt019x=     [HW,ALSA]
2325
2326        snd-dummy=      [HW,ALSA]
2327
2328        snd-emu10k1=    [HW,ALSA]
2329
2330        snd-ens1370=    [HW,ALSA]
2331
2332        snd-ens1371=    [HW,ALSA]
2333
2334        snd-es968=      [HW,ALSA]
2335
2336        snd-es1688=     [HW,ALSA]
2337
2338        snd-es18xx=     [HW,ALSA]
2339
2340        snd-es1938=     [HW,ALSA]
2341
2342        snd-es1968=     [HW,ALSA]
2343
2344        snd-fm801=      [HW,ALSA]
2345
2346        snd-gusclassic= [HW,ALSA]
2347
2348        snd-gusextreme= [HW,ALSA]
2349
2350        snd-gusmax=     [HW,ALSA]
2351
2352        snd-hdsp=       [HW,ALSA]
2353
2354        snd-ice1712=    [HW,ALSA]
2355
2356        snd-intel8x0=   [HW,ALSA]
2357
2358        snd-interwave=  [HW,ALSA]
2359
2360        snd-interwave-stb=
2361                        [HW,ALSA]
2362
2363        snd-korg1212=   [HW,ALSA]
2364
2365        snd-maestro3=   [HW,ALSA]
2366
2367        snd-mpu401=     [HW,ALSA]
2368
2369        snd-mtpav=      [HW,ALSA]
2370
2371        snd-nm256=      [HW,ALSA]
2372
2373        snd-opl3sa2=    [HW,ALSA]
2374
2375        snd-opti92x-ad1848=
2376                        [HW,ALSA]
2377
2378        snd-opti92x-cs4231=
2379                        [HW,ALSA]
2380
2381        snd-opti93x=    [HW,ALSA]
2382
2383        snd-pmac=       [HW,ALSA]
2384
2385        snd-rme32=      [HW,ALSA]
2386
2387        snd-rme96=      [HW,ALSA]
2388
2389        snd-rme9652=    [HW,ALSA]
2390
2391        snd-sb8=        [HW,ALSA]
2392
2393        snd-sb16=       [HW,ALSA]
2394
2395        snd-sbawe=      [HW,ALSA]
2396
2397        snd-serial=     [HW,ALSA]
2398
2399        snd-sgalaxy=    [HW,ALSA]
2400
2401        snd-sonicvibes= [HW,ALSA]
2402
2403        snd-sun-amd7930=
2404                        [HW,ALSA]
2405
2406        snd-sun-cs4231= [HW,ALSA]
2407
2408        snd-trident=    [HW,ALSA]
2409
2410        snd-usb-audio=  [HW,ALSA,USB]
2411
2412        snd-via82xx=    [HW,ALSA]
2413
2414        snd-virmidi=    [HW,ALSA]
2415
2416        snd-wavefront=  [HW,ALSA]
2417
2418        snd-ymfpci=     [HW,ALSA]
2419
2420        softlockup_panic=
2421                        [KNL] Should the soft-lockup detector generate panics.
2422
2423        sonypi.*=       [HW] Sony Programmable I/O Control Device driver
2424                        See Documentation/sonypi.txt
2425
2426        specialix=      [HW,SERIAL] Specialix multi-serial port adapter
2427                        See Documentation/serial/specialix.txt.
2428
2429        spia_io_base=   [HW,MTD]
2430        spia_fio_base=
2431        spia_pedr=
2432        spia_peddr=
2433
2434        sscape=         [HW,OSS]
2435                        Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2436
2437        st=             [HW,SCSI] SCSI tape parameters (buffers, etc.)
2438                        See Documentation/scsi/st.txt.
2439
2440        stacktrace      [FTRACE]
2441                        Enabled the stack tracer on boot up.
2442
2443        sti=            [PARISC,HW]
2444                        Format: <num>
2445                        Set the STI (builtin display/keyboard on the HP-PARISC
2446                        machines) console (graphic card) which should be used
2447                        as the initial boot-console.
2448                        See also comment in drivers/video/console/sticore.c.
2449
2450        sti_font=       [HW]
2451                        See comment in drivers/video/console/sticore.c.
2452
2453        stifb=          [HW]
2454                        Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2455
2456        sunrpc.min_resvport=
2457        sunrpc.max_resvport=
2458                        [NFS,SUNRPC]
2459                        SunRPC servers often require that client requests
2460                        originate from a privileged port (i.e. a port in the
2461                        range 0 < portnr < 1024).
2462                        An administrator who wishes to reserve some of these
2463                        ports for other uses may adjust the range that the
2464                        kernel's sunrpc client considers to be privileged
2465                        using these two parameters to set the minimum and
2466                        maximum port values.
2467
2468        sunrpc.pool_mode=
2469                        [NFS]
2470                        Control how the NFS server code allocates CPUs to
2471                        service thread pools.  Depending on how many NICs
2472                        you have and where their interrupts are bound, this
2473                        option will affect which CPUs will do NFS serving.
2474                        Note: this parameter cannot be changed while the
2475                        NFS server is running.
2476
2477                        auto        the server chooses an appropriate mode
2478                                    automatically using heuristics
2479                        global      a single global pool contains all CPUs
2480                        percpu      one pool for each CPU
2481                        pernode     one pool for each NUMA node (equivalent
2482                                    to global on non-NUMA machines)
2483
2484        sunrpc.tcp_slot_table_entries=
2485        sunrpc.udp_slot_table_entries=
2486                        [NFS,SUNRPC]
2487                        Sets the upper limit on the number of simultaneous
2488                        RPC calls that can be sent from the client to a
2489                        server. Increasing these values may allow you to
2490                        improve throughput, but will also increase the
2491                        amount of memory reserved for use by the client.
2492
2493        swiotlb=        [IA-64] Number of I/O TLB slabs
2494
2495        switches=       [HW,M68k]
2496
2497        sym53c416=      [HW,SCSI]
2498                        See header of drivers/scsi/sym53c416.c.
2499
2500        sysrq_always_enabled
2501                        [KNL]
2502                        Ignore sysrq setting - this boot parameter will
2503                        neutralize any effect of /proc/sys/kernel/sysrq.
2504                        Useful for debugging.
2505
2506        t128=           [HW,SCSI]
2507                        See header of drivers/scsi/t128.c.
2508
2509        tdfx=           [HW,DRM]
2510
2511        test_suspend=   [SUSPEND]
2512                        Specify "mem" (for Suspend-to-RAM) or "standby" (for
2513                        standby suspend) as the system sleep state to briefly
2514                        enter during system startup.  The system is woken from
2515                        this state using a wakeup-capable RTC alarm.
2516
2517        thash_entries=  [KNL,NET]
2518                        Set number of hash buckets for TCP connection
2519
2520        thermal.act=    [HW,ACPI]
2521                        -1: disable all active trip points in all thermal zones
2522                        <degrees C>: override all lowest active trip points
2523
2524        thermal.crt=    [HW,ACPI]
2525                        -1: disable all critical trip points in all thermal zones
2526                        <degrees C>: override all critical trip points
2527
2528        thermal.nocrt=  [HW,ACPI]
2529                        Set to disable actions on ACPI thermal zone
2530                        critical and hot trip points.
2531
2532        thermal.off=    [HW,ACPI]
2533                        1: disable ACPI thermal control
2534
2535        thermal.psv=    [HW,ACPI]
2536                        -1: disable all passive trip points
2537                        <degrees C>: override all passive trip points to this
2538                        value
2539
2540        thermal.tzp=    [HW,ACPI]
2541                        Specify global default ACPI thermal zone polling rate
2542                        <deci-seconds>: poll all this frequency
2543                        0: no polling (default)
2544
2545        tmscsim=        [HW,SCSI]
2546                        See comment before function dc390_setup() in
2547                        drivers/scsi/tmscsim.c.
2548
2549        topology=       [S390]
2550                        Format: {off | on}
2551                        Specify if the kernel should make use of the cpu
2552                        topology informations if the hardware supports these.
2553                        The scheduler will make use of these informations and
2554                        e.g. base its process migration decisions on it.
2555                        Default is off.
2556
2557        tp720=          [HW,PS2]
2558
2559        trace_buf_size=nn[KMG]
2560                        [FTRACE] will set tracing buffer size.
2561
2562        trace_event=[event-list]
2563                        [FTRACE] Set and start specified trace events in order
2564                        to facilitate early boot debugging.
2565                        See also Documentation/trace/events.txt
2566
2567        trix=           [HW,OSS] MediaTrix AudioTrix Pro
2568                        Format:
2569                        <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2570
2571        tsc=            Disable clocksource-must-verify flag for TSC.
2572                        Format: <string>
2573                        [x86] reliable: mark tsc clocksource as reliable, this
2574                        disables clocksource verification at runtime.
2575                        Used to enable high-resolution timer mode on older
2576                        hardware, and in virtualized environment.
2577
2578        turbografx.map[2|3]=    [HW,JOY]
2579                        TurboGraFX parallel port interface
2580                        Format:
2581                        <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2582                        See also Documentation/input/joystick-parport.txt
2583
2584        u14-34f=        [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2585                        See header of drivers/scsi/u14-34f.c.
2586
2587        uart401=        [HW,OSS]
2588                        Format: <io>,<irq>
2589
2590        uart6850=       [HW,OSS]
2591                        Format: <io>,<irq>
2592
2593        uhci-hcd.ignore_oc=
2594                        [USB] Ignore overcurrent events (default N).
2595                        Some badly-designed motherboards generate lots of
2596                        bogus events, for ports that aren't wired to
2597                        anything.  Set this parameter to avoid log spamming.
2598                        Note that genuine overcurrent events won't be
2599                        reported either.
2600
2601        unknown_nmi_panic
2602                        [X86]
2603                        Set unknown_nmi_panic=1 early on boot.
2604
2605        usbcore.autosuspend=
2606                        [USB] The autosuspend time delay (in seconds) used
2607                        for newly-detected USB devices (default 2).  This
2608                        is the time required before an idle device will be
2609                        autosuspended.  Devices for which the delay is set
2610                        to a negative value won't be autosuspended at all.
2611
2612        usbcore.usbfs_snoop=
2613                        [USB] Set to log all usbfs traffic (default 0 = off).
2614
2615        usbcore.blinkenlights=
2616                        [USB] Set to cycle leds on hubs (default 0 = off).
2617
2618        usbcore.old_scheme_first=
2619                        [USB] Start with the old device initialization
2620                        scheme (default 0 = off).
2621
2622        usbcore.use_both_schemes=
2623                        [USB] Try the other device initialization scheme
2624                        if the first one fails (default 1 = enabled).
2625
2626        usbcore.initial_descriptor_timeout=
2627                        [USB] Specifies timeout for the initial 64-byte
2628                        USB_REQ_GET_DESCRIPTOR request in milliseconds
2629                        (default 5000 = 5.0 seconds).
2630
2631        usbhid.mousepoll=
2632                        [USBHID] The interval which mice are to be polled at.
2633
2634        usb-storage.delay_use=
2635                        [UMS] The delay in seconds before a new device is
2636                        scanned for Logical Units (default 5).
2637
2638        usb-storage.quirks=
2639                        [UMS] A list of quirks entries to supplement or
2640                        override the built-in unusual_devs list.  List
2641                        entries are separated by commas.  Each entry has
2642                        the form VID:PID:Flags where VID and PID are Vendor
2643                        and Product ID values (4-digit hex numbers) and
2644                        Flags is a set of characters, each corresponding
2645                        to a common usb-storage quirk flag as follows:
2646                                a = SANE_SENSE (collect more than 18 bytes
2647                                        of sense data);
2648                                c = FIX_CAPACITY (decrease the reported
2649                                        device capacity by one sector);
2650                                h = CAPACITY_HEURISTICS (decrease the
2651                                        reported device capacity by one
2652                                        sector if the number is odd);
2653                                i = IGNORE_DEVICE (don't bind to this
2654                                        device);
2655                                l = NOT_LOCKABLE (don't try to lock and
2656                                        unlock ejectable media);
2657                                m = MAX_SECTORS_64 (don't transfer more
2658                                        than 64 sectors = 32 KB at a time);
2659                                o = CAPACITY_OK (accept the capacity
2660                                        reported by the device);
2661                                r = IGNORE_RESIDUE (the device reports
2662                                        bogus residue values);
2663                                s = SINGLE_LUN (the device has only one
2664                                        Logical Unit);
2665                                w = NO_WP_DETECT (don't test whether the
2666                                        medium is write-protected).
2667                        Example: quirks=0419:aaf5:rl,0421:0433:rc
2668
2669        vdso=           [X86,SH]
2670                        vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2671                        vdso=1: enable VDSO (default)
2672                        vdso=0: disable VDSO mapping
2673
2674        vdso32=         [X86]
2675                        vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2676                        vdso32=1: enable 32-bit VDSO (default)
2677                        vdso32=0: disable 32-bit VDSO mapping
2678
2679        vector=         [IA-64,SMP]
2680                        vector=percpu: enable percpu vector domain
2681
2682        video=          [FB] Frame buffer configuration
2683                        See Documentation/fb/modedb.txt.
2684
2685        vga=            [BOOT,X86-32] Select a particular video mode
2686                        See Documentation/x86/boot.txt and
2687                        Documentation/svga.txt.
2688                        Use vga=ask for menu.
2689                        This is actually a boot loader parameter; the value is
2690                        passed to the kernel using a special protocol.
2691
2692        vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2693                        size of <nn>. This can be used to increase the
2694                        minimum size (128MB on x86). It can also be used to
2695                        decrease the size and leave more room for directly
2696                        mapped kernel RAM.
2697
2698        vmhalt=         [KNL,S390] Perform z/VM CP command after system halt.
2699                        Format: <command>
2700
2701        vmpanic=        [KNL,S390] Perform z/VM CP command after kernel panic.
2702                        Format: <command>
2703
2704        vmpoff=         [KNL,S390] Perform z/VM CP command after power off.
2705                        Format: <command>
2706
2707        vt.default_blu= [VT]
2708                        Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2709                        Change the default blue palette of the console.
2710                        This is a 16-member array composed of values
2711                        ranging from 0-255.
2712
2713        vt.default_grn= [VT]
2714                        Format: <green0>,<green1>,<green2>,...,<green15>
2715                        Change the default green palette of the console.
2716                        This is a 16-member array composed of values
2717                        ranging from 0-255.
2718
2719        vt.default_red= [VT]
2720                        Format: <red0>,<red1>,<red2>,...,<red15>
2721                        Change the default red palette of the console.
2722                        This is a 16-member array composed of values
2723                        ranging from 0-255.
2724
2725        vt.default_utf8=
2726                        [VT]
2727                        Format=<0|1>
2728                        Set system-wide default UTF-8 mode for all tty's.
2729                        Default is 1, i.e. UTF-8 mode is enabled for all
2730                        newly opened terminals.
2731
2732        waveartist=     [HW,OSS]
2733                        Format: <io>,<irq>,<dma>,<dma2>
2734
2735        wd33c93=        [HW,SCSI]
2736                        See header of drivers/scsi/wd33c93.c.
2737
2738        wd7000=         [HW,SCSI]
2739                        See header of drivers/scsi/wd7000.c.
2740
2741        wdt=            [WDT] Watchdog
2742                        See Documentation/watchdog/wdt.txt.
2743
2744        x2apic_phys     [X86-64,APIC] Use x2apic physical mode instead of
2745                        default x2apic cluster mode on platforms
2746                        supporting x2apic.
2747
2748        xd=             [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2749        xd_geo=         See header of drivers/block/xd.c.
2750
2751        xirc2ps_cs=     [NET,PCMCIA]
2752                        Format:
2753                        <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2754
2755______________________________________________________________________
2756
2757TODO:
2758
2759        Add documentation for ALSA options.
2760        Add more DRM drivers.
2761
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