4 The 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
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IMA Integrity measurement architecture is enabled.
48 IOSCHED More than one I/O scheduler is enabled.
49 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
50 ISAPNP ISA PnP code is enabled.
51 ISDN Appropriate ISDN support is enabled.
52 JOY Appropriate joystick support is enabled.
53 KMEMTRACE kmemtrace is enabled.
54 LIBATA Libata driver is enabled
55 LP Printer support is enabled.
56 LOOP Loopback device support is enabled.
57 M68k M68k architecture is enabled.
58 These options have more detailed description inside of
59 Documentation/m68k/kernel-options.txt.
60 MCA MCA bus support is enabled.
61 MDA MDA console support is enabled.
62 MOUSE Appropriate mouse support is enabled.
63 MSI Message Signaled Interrupts (PCI).
64 MTD MTD (Memory Technology Device) support is enabled.
65 NET Appropriate network support is enabled.
66 NUMA NUMA support is enabled.
67 GENERIC_TIME The generic timeofday code is enabled.
68 NFS Appropriate NFS support is enabled.
69 OSS OSS sound support is enabled.
70 PV_OPS A paravirtualized kernel is enabled.
71 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
72 PARISC The PA-RISC architecture is enabled.
73 PCI PCI bus support is enabled.
74 PCIE PCI Express support is enabled.
75 PCMCIA The PCMCIA subsystem is enabled.
76 PNP Plug & Play support is enabled.
77 PPC PowerPC architecture is enabled.
78 PPT Parallel port support is enabled.
79 PS2 Appropriate PS/2 support is enabled.
80 RAM RAM disk support is enabled.
81 ROOTPLUG The example Root Plug LSM is enabled.
82 S390 S390 architecture is enabled.
83 SCSI Appropriate SCSI support is enabled.
84 A lot of drivers has their options described inside of
86 SECURITY Different security models are enabled.
87 SELINUX SELinux support is enabled.
88 SERIAL Serial support is enabled.
89 SH SuperH architecture is enabled.
90 SMP The kernel is an SMP kernel.
91 SPARC Sparc architecture is enabled.
92 SWSUSP Software suspend (hibernation) is enabled.
93 SUSPEND System suspend states are enabled.
94 FTRACE Function tracing enabled.
95 TS Appropriate touchscreen support is enabled.
96 UMS USB Mass Storage support is enabled.
97 USB USB support is enabled.
98 USBHID USB Human Interface Device support is enabled.
99 V4L Video For Linux support is enabled.
100 VGA The VGA console has been enabled.
101 VT Virtual terminal support is enabled.
102 WDT Watchdog support is enabled.
103 XT IBM PC/XT MFM hard disk support is enabled.
104 X86-32 X86-32, aka i386 architecture is enabled.
105 X86-64 X86-64 architecture is enabled.
106 More X86-64 boot options can be found in
107 Documentation/x86/x86_64/boot-options.txt .
108 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
110 In addition, the following text indicates that the option:
112 BUGS= Relates to possible processor bugs on the said processor.
113 KNL Is a kernel start-up parameter.
114 BOOT Is a boot loader parameter.
116 Parameters denoted with BOOT are actually interpreted by the boot
117 loader, and have no meaning to the kernel directly.
118 Do not modify the syntax of boot loader parameters without extreme
119 need or coordination with <Documentation/x86/boot.txt>.
121 There are also arch-specific kernel-parameters not documented here.
122 See for example <Documentation/x86/x86_64/boot-options.txt>.
124 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
125 a trailing = on the name of any parameter states that that parameter will
126 be entered as an environment variable, whereas its absence indicates that
127 it will appear as a kernel argument readable via /proc/cmdline by programs
128 running once the system is up.
130 The number of kernel parameters is not limited, but the length of the
131 complete command line (parameters including spaces etc.) is limited to
132 a fixed number of characters. This limit depends on the architecture
133 and is between 256 and 4096 characters. It is defined in the file
134 ./include/asm/setup.h as COMMAND_LINE_SIZE.
138 Advanced Configuration and Power Interface
139 Format: { force | off | ht | strict | noirq | rsdt }
140 force -- enable ACPI if default was off
141 off -- disable ACPI if default was on
142 noirq -- do not use ACPI for IRQ routing
143 ht -- run only enough ACPI to enable Hyper Threading
144 strict -- Be less tolerant of platforms that are not
145 strictly ACPI specification compliant.
146 rsdt -- prefer RSDT over (default) XSDT
148 See also Documentation/power/pm.txt, pci=noacpi
150 acpi_apic_instance= [ACPI, IOAPIC]
152 2: use 2nd APIC table, if available
153 1,0: use 1st APIC table
156 acpi_backlight= [HW,ACPI]
157 acpi_backlight=vendor
159 If set to vendor, prefer vendor specific driver
160 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
161 of the ACPI video.ko driver.
163 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
164 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
166 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
167 debug output. Bits in debug_layer correspond to a
168 _COMPONENT in an ACPI source file, e.g.,
169 #define _COMPONENT ACPI_PCI_COMPONENT
170 Bits in debug_level correspond to a level in
171 ACPI_DEBUG_PRINT statements, e.g.,
172 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
173 The debug_level mask defaults to "info". See
174 Documentation/acpi/debug.txt for more information about
175 debug layers and levels.
177 Enable processor driver info messages:
178 acpi.debug_layer=0x20000000
179 Enable PCI/PCI interrupt routing info messages:
180 acpi.debug_layer=0x400000
181 Enable AML "Debug" output, i.e., stores to the Debug
182 object while interpreting AML:
183 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
184 Enable all messages related to ACPI hardware:
185 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
187 Some values produce so much output that the system is
188 unusable. The "log_buf_len" parameter may be useful
189 if you need to capture more output.
191 acpi_display_output= [HW,ACPI]
192 acpi_display_output=vendor
193 acpi_display_output=video
196 acpi_irq_balance [HW,ACPI]
197 ACPI will balance active IRQs
200 acpi_irq_nobalance [HW,ACPI]
201 ACPI will not move active IRQs (default)
204 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
205 Format: <irq>,<irq>...
207 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
209 Format: <irq>,<irq>...
211 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
213 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
214 Format: To spoof as Windows 98: ="Microsoft Windows"
216 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
217 acpi_osi="string1" # add string1 -- only one string
218 acpi_osi="!string2" # remove built-in string2
219 acpi_osi= # disable all strings
222 Override the pmtimer bug detection: force the kernel
223 to assume that this machine's pmtimer latches its value
224 and always returns good values.
226 acpi.power_nocheck= [HW,ACPI]
227 Format: 1/0 enable/disable the check of power state.
228 On some bogus BIOS the _PSC object/_STA object of
229 power resource can't return the correct device power
230 state. In such case it is unneccessary to check its
231 power state again in power transition.
232 1 : disable the power state check
234 acpi_enforce_resources= [ACPI]
235 { strict | lax | no }
236 Check for resource conflicts between native drivers
237 and ACPI OperationRegions (SystemIO and SystemMemory
238 only). IO ports and memory declared in ACPI might be
239 used by the ACPI subsystem in arbitrary AML code and
240 can interfere with legacy drivers.
241 strict (default): access to resources claimed by ACPI
242 is denied; legacy drivers trying to access reserved
243 resources will fail to bind to device using them.
244 lax: access to resources claimed by ACPI is allowed;
245 legacy drivers trying to access reserved resources
246 will bind successfully but a warning message is logged.
247 no: ACPI OperationRegions are not marked as reserved,
248 no further checks are performed.
251 Format: <io>,<irq>,<dma>,<dma2>,<type>
254 See header of drivers/scsi/advansys.c.
256 advwdt= [HW,WDT] Advantech WDT
257 Format: <iostart>,<iostop>
259 aedsp16= [HW,OSS] Audio Excel DSP 16
260 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
261 See also header of sound/oss/aedsp16.c.
264 { off | try_unsupported }
265 off: disable AGP support
266 try_unsupported: try to drive unsupported chipsets
267 (may crash computer or cause data corruption)
270 See Documentation/scsi/aha152x.txt.
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
276 See Documentation/scsi/aic7xxx.txt.
279 See Documentation/scsi/aic79xx.txt.
281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
287 share - put every device behind one IOMMU into the
288 same protection domain
289 fullflush - enable flushing of IO/TLB entries when
290 they are unmapped. Otherwise they are
291 flushed before they will be reused, which
294 amd_iommu_size= [HW,X86-64]
295 Define the size of the aperture for the AMD IOMMU
296 driver. Possible values are:
297 '32M', '64M' (default), '128M', '256M', '512M', '1G'
299 amijoy.map= [HW,JOY] Amiga joystick support
300 Map of devices attached to JOY0DAT and JOY1DAT
302 See also Documentation/kernel/input/joystick.txt
304 analog.map= [HW,JOY] Analog joystick and gamepad support
305 Specifies type or capabilities of an analog joystick
306 connected to one of 16 gameports
307 Format: <type1>,<type2>,..<type16>
310 Power management functions (SPARCstation-4/5 + deriv.)
312 Disable APC CPU standby support. SPARCstation-Fox does
313 not play well with APC CPU idle - disable it if you have
314 APC and your system crashes randomly.
316 apic= [APIC,i386] Advanced Programmable Interrupt Controller
317 Change the output verbosity whilst booting
318 Format: { quiet (default) | verbose | debug }
319 Change the amount of debugging information output
320 when initialising the APIC and IO-APIC components.
322 apm= [APM] Advanced Power Management
323 See header of arch/x86/kernel/apm_32.c.
325 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
326 Format: <io>,<irq>,<nodeID>
330 atarimouse= [HW,MOUSE] Atari Mouse
332 atascsi= [HW,SCSI] Atari SCSI
334 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
335 EzKey and similar keyboards
337 atkbd.reset= [HW] Reset keyboard during initialization
339 atkbd.set= [HW] Select keyboard code set
340 Format: <int> (2 = AT (default), 3 = PS/2)
342 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
345 atkbd.softraw= [HW] Choose between synthetic and real raw mode
346 Format: <bool> (0 = real, 1 = synthetic (default))
348 atkbd.softrepeat= [HW]
349 Use software keyboard repeat
353 baycom_epp= [HW,AX25]
356 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
358 See header of drivers/net/hamradio/baycom_par.c.
360 baycom_ser_fdx= [HW,AX25]
361 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
362 Format: <io>,<irq>,<mode>[,<baud>]
363 See header of drivers/net/hamradio/baycom_ser_fdx.c.
365 baycom_ser_hdx= [HW,AX25]
366 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
367 Format: <io>,<irq>,<mode>
368 See header of drivers/net/hamradio/baycom_ser_hdx.c.
370 boot_delay= Milliseconds to delay each printk during boot.
371 Values larger than 10 seconds (10000) are changed to
375 bootmem_debug [KNL] Enable bootmem allocator debug messages.
377 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
378 bttv.radio= Most important insmod options are available as
380 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
381 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
384 See drivers/scsi/BusLogic.c, comment before function
385 BusLogic_ParseDriverOptions().
387 c101= [NET] Moxa C101 synchronous serial card
389 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
390 Sometimes CPU hardware bugs make them report the cache
391 size incorrectly. The kernel will attempt work arounds
392 to fix known problems, but for some CPUs it is not
393 possible to determine what the correct size should be.
394 This option provides an override for these situations.
397 [SECURITY] Disable capabilities. This would normally
398 be used only if an alternative security model is to be
399 configured. Potentially dangerous and should only be
400 used if you are entirely sure of the consequences.
402 ccw_timeout_log [S390]
403 See Documentation/s390/CommonIO for details.
405 cgroup_disable= [KNL] Disable a particular controller
406 Format: {name of the controller(s) to disable}
407 {Currently supported controllers - "memory"}
409 checkreqprot [SELINUX] Set initial checkreqprot flag value.
410 Format: { "0" | "1" }
411 See security/selinux/Kconfig help text.
412 0 -- check protection applied by kernel (includes
413 any implied execute protection).
414 1 -- check protection requested by application.
415 Default value is set via a kernel config option.
416 Value can be changed at runtime via
417 /selinux/checkreqprot.
420 See Documentation/s390/CommonIO for details.
422 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
424 Forces specified clocksource (if available) to be used
425 when calculating gettimeofday(). If specified
426 clocksource is not available, it defaults to PIT.
427 Format: { pit | tsc | cyclone | pmtmr }
429 clocksource= [GENERIC_TIME] Override the default clocksource
431 Override the default clocksource and use the clocksource
432 with the name specified.
433 Some clocksource names to choose from, depending on
435 [all] jiffies (this is the base, fallback clocksource)
437 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
438 pxa_timer,timer3,32k_counter,timer0_1
440 [X86-32] pit,hpet,tsc,vmi-timer;
441 scx200_hrt on Geode; cyclone on IBM x440
449 clearcpuid=BITNUM [X86]
450 Disable CPUID feature X for the kernel. See
451 arch/x86/include/asm/cpufeature.h for the valid bit
452 numbers. Note the Linux specific bits are not necessarily
453 stable over kernel options, but the vendor specific
455 Also note that user programs calling CPUID directly
456 or using the feature without checking anything
457 will still see it. This just prevents it from
458 being used by the kernel or shown in /proc/cpuinfo.
459 Also note the kernel might malfunction if you disable
462 code_bytes [X86] How many bytes of object code to print
467 com20020= [HW,NET] ARCnet - COM20020 chipset
469 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
471 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
475 ARCnet - COM90xx chipset (memory-mapped buffers)
476 Format: <io>[,<irq>[,<memstart>]]
478 condev= [HW,S390] console device
481 console= [KNL] Output console device and options.
483 tty<n> Use the virtual console device <n>.
487 Use the specified serial port. The options are of
488 the form "bbbbpnf", where "bbbb" is the baud rate,
489 "p" is parity ("n", "o", or "e"), "n" is number of
490 bits, and "f" is flow control ("r" for RTS or
491 omit it). Default is "9600n8".
493 See Documentation/serial-console.txt for more
495 Documentation/networking/netconsole.txt for an
498 uart[8250],io,<addr>[,options]
499 uart[8250],mmio,<addr>[,options]
500 Start an early, polled-mode console on the 8250/16550
501 UART at the specified I/O port or MMIO address,
502 switching to the matching ttyS device later. The
503 options are the same as for ttyS, above.
505 If the device connected to the port is not a TTY but a braille
506 device, prepend "brl," before the device type, for instance
508 For now, only VisioBraille is supported.
511 [KNL] Change the default value for
512 /proc/<pid>/coredump_filter.
513 See also Documentation/filesystems/proc.txt.
515 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
517 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
519 crashkernel=nn[KMG]@ss[KMG]
520 [KNL] Reserve a chunk of physical memory to
521 hold a kernel to switch to with kexec on panic.
523 crashkernel=range1:size1[,range2:size2,...][@offset]
524 [KNL] Same as above, but depends on the memory
525 in the running system. The syntax of range is
526 start-[end] where start and end are both
527 a memory unit (amount[KMG]). See also
528 Documentation/kdump/kdump.txt for a example.
533 cs89x0_media= [HW,NET]
534 Format: { rj45 | aui | bnc }
537 See header of drivers/s390/block/dasd_devmap.c.
539 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
540 (one device per port)
541 Format: <port#>,<type>
542 See also Documentation/input/joystick-parport.txt
544 debug [KNL] Enable kernel debugging (events log level).
547 [KNL] verbose self-tests
549 Print debugging info while doing the locking API
551 We default to 0 (no extra messages), setting it to
552 1 will print _a lot_ more information - normally
553 only useful to kernel developers.
555 debug_objects [KNL] Enable object debugging
558 [KNL] Disable object debugging
560 debugpat [X86] Enable PAT debugging
562 decnet.addr= [HW,NET]
563 Format: <area>[,<node>]
564 See also Documentation/networking/decnet.txt.
567 [same as hugepagesz=] The size of the default
568 HugeTLB page size. This is the size represented by
569 the legacy /proc/ hugepages APIs, used for SHM, and
570 default size when mounting hugetlbfs filesystems.
571 Defaults to the default architecture's huge page size
575 Set number of hash buckets for dentry cache.
578 IO parameters + enable/disable command.
580 digiepca= [HW,SERIAL]
581 See drivers/char/README.epca and
582 Documentation/serial/digiepca.txt.
584 disable_mtrr_cleanup [X86]
585 The kernel tries to adjust MTRR layout from continuous
586 to discrete, to make X server driver able to add WB
587 entry later. This parameter disables that.
589 disable_mtrr_trim [X86, Intel and AMD only]
590 By default the kernel will trim any uncacheable
591 memory out of your available memory pool based on
592 MTRR settings. This parameter disables that behavior,
593 possibly causing your machine to run very slowly.
595 disable_timer_pin_1 [X86]
596 Disable PIN 1 of APIC timer
597 Can be useful to work around chipset bugs.
599 dmasound= [HW,OSS] Sound subsystem buffers
601 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
602 this option disables the debugging code at boot.
604 dma_debug_entries=<number>
605 This option allows to tune the number of preallocated
606 entries for DMA-API debugging code. One entry is
607 required per DMA-API allocation. Use this if the
608 DMA-API debugging code disables itself because the
609 architectural default is too low.
615 dynamic_printk Enables pr_debug()/dev_dbg() calls if
616 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
617 These can also be switched on/off via
618 <debugfs>/dynamic_printk/modules
620 earlycon= [KNL] Output early console device and options.
621 uart[8250],io,<addr>[,options]
622 uart[8250],mmio,<addr>[,options]
623 Start an early, polled-mode console on the 8250/16550
624 UART at the specified I/O port or MMIO address.
625 The options are the same as for ttyS, above.
627 earlyprintk= [X86,SH,BLACKFIN]
629 earlyprintk=serial[,ttySn[,baudrate]]
632 Append ",keep" to not disable it when the real console
635 Only vga or serial or usb debug port at a time.
637 Currently only ttyS0 and ttyS1 are supported.
639 Interaction with the standard serial driver is not
642 The VGA output is eventually overwritten by the real
648 Format: {"off" | "on" | "skip[mbr]"}
650 eisa_irq_edge= [PARISC,HW]
651 See header of drivers/parisc/eisa.c.
654 See comment before function elanfreq_setup() in
655 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
658 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
659 See Documentation/block/as-iosched.txt and
660 Documentation/block/deadline-iosched.txt for details.
662 elfcorehdr= [IA64,PPC,SH,X86]
663 Specifies physical address of start of kernel core
664 image elf header. Generally kexec loader will
665 pass this option to capture kernel.
666 See Documentation/kdump/kdump.txt for details.
668 enable_mtrr_cleanup [X86]
669 The kernel tries to adjust MTRR layout from continuous
670 to discrete, to make X server driver able to add WB
671 entry later. This parameter enables that.
673 enable_timer_pin_1 [i386,x86-64]
674 Enable PIN 1 of APIC timer
675 Can be useful to work around chipset bugs
676 (in particular on some ATI chipsets).
677 The kernel tries to set a reasonable default.
679 enforcing [SELINUX] Set initial enforcing status.
681 See security/selinux/Kconfig help text.
682 0 -- permissive (log only, no denials).
683 1 -- enforcing (deny and log).
685 Value can be changed at runtime via /selinux/enforce.
687 ether= [HW,NET] Ethernet cards parameters
688 This option is obsoleted by the "netdev=" option, which
689 has equivalent usage. See its documentation for details.
691 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
696 fail_make_request=[KNL]
697 General fault injection mechanism.
698 Format: <interval>,<probability>,<space>,<times>
699 See also /Documentation/fault-injection/.
702 See header of drivers/scsi/fd_mcs.c.
705 See header of drivers/scsi/fdomain.c.
708 See Documentation/blockdev/floppy.txt.
710 force_pal_cache_flush
711 [IA-64] Avoid check_sal_cache_flush which may hang on
712 buggy SAL_CACHE_FLUSH implementations. Using this
713 parameter will force ia64_sal_cache_flush to call
714 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
717 [ftrace] will set and start the specified tracer
718 as early as possible in order to facilitate early
722 [ftrace] will dump the trace buffers on oops.
725 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
726 support via parallel port (up to 5 devices per port)
727 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
728 See also Documentation/input/joystick-parport.txt
732 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
737 See header of drivers/scsi/gdth.c.
739 gpt [EFI] Forces disk with valid GPT signature but
740 invalid Protective MBR to be treated as GPT.
744 hashdist= [KNL,NUMA] Large hashes allocated during boot
745 are distributed across NUMA nodes. Defaults on
746 for IA-64, off otherwise.
747 Format: 0 | 1 (for off | on)
749 hcl= [IA-64] SGI's Hardware Graph compatibility layer
751 hd= [EIDE] (E)IDE hard drive subsystem geometry
752 Format: <cyl>,<head>,<sect>
754 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
755 size of <nn>. This works even on boxes that have no
756 highmem otherwise. This also works to reduce highmem
757 size on bigger boxes.
759 highres= [KNL] Enable/disable high resolution timer mode.
760 Valid parameters: "on", "off"
764 See Documentation/isdn/README.HiSax.
768 hpet= [X86-32,HPET] option to control HPET usage
769 Format: { enable (default) | disable | force |
771 disable: disable HPET and use PIT instead
772 force: allow force enabled of undocumented chips (ICH4,
774 verbose: show contents of HPET registers during setup
776 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
777 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
778 On x86-64 and powerpc, this option can be specified
779 multiple times interleaved with hugepages= to reserve
780 huge pages of different sizes. Valid pages sizes on
781 x86-64 are 2M (when the CPU supports "pse") and 1G
782 (when the CPU supports the "pdpe1gb" cpuinfo flag)
783 Note that 1GB pages can only be allocated at boot time
784 using hugepages= and not freed afterwards.
786 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
787 terminal devices. Valid values: 0..8
788 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
789 If specified, z/VM IUCV HVC accepts connections
790 from listed z/VM user IDs only.
792 i2c_bus= [HW] Override the default board specific I2C bus speed
793 or register an additional I2C bus that is not
794 registered from board initialization code.
798 i8042.debug [HW] Toggle i8042 debug mode
799 i8042.direct [HW] Put keyboard port into non-translated mode
800 i8042.dumbkbd [HW] Pretend that controller can only read data from
801 keyboard and cannot control its state
802 (Don't attempt to blink the leds)
803 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
804 i8042.nokbd [HW] Don't check/create keyboard port
805 i8042.noloop [HW] Disable the AUX Loopback command while probing
807 i8042.nomux [HW] Don't check presence of an active multiplexing
809 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
812 [HW] Frequency with which keyboard LEDs should blink
813 when kernel panics (default is 0.5 sec)
814 i8042.reset [HW] Reset the controller during init and cleanup
815 i8042.unlock [HW] Unlock (ignore) the keylock
819 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
820 indicates that the driver is running on unsupported
822 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
823 does not match list of supported models.
825 [HW] Report power status in /proc/i8k
826 (disabled by default)
827 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
830 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
831 See Documentation/mca.txt.
834 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
836 ide-core.nodma= [HW] (E)IDE subsystem
837 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
838 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
839 .cdrom .chs .ignore_cable are additional options
840 See Documentation/ide/ide.txt.
842 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
843 Claim all unknown PCI IDE storage controllers.
846 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
847 Poll forces a polling idle loop that can slightly
848 improve the performance of waking up a idle CPU, but
849 will use a lot of power and make the system run hot.
851 idle=mwait: On systems which support MONITOR/MWAIT but
852 the kernel chose to not use it because it doesn't save
853 as much power as a normal idle loop, use the
854 MONITOR/MWAIT idle loop anyways. Performance should be
855 the same as idle=poll.
856 idle=halt: Halt is forced to be used for CPU idle.
857 In such case C2/C3 won't be used again.
858 idle=nomwait: Disable mwait for CPU C-states
860 ignore_loglevel [KNL]
861 Ignore loglevel setting - this will print /all/
862 kernel messages to the console. Useful for debugging.
865 Set number of hash buckets for inode cache.
868 Format: { "0" | "1" }
869 0 -- integrity auditing messages. (Default)
870 1 -- enable informational integrity auditing messages.
873 Formt: { "sha1" | "md5" }
877 See header of drivers/scsi/in2000.c.
881 Run specified binary instead of /sbin/init as init
884 initcall_debug [KNL] Trace initcalls as they are executed. Useful
885 for working out where the kernel is dying during
888 initrd= [BOOT] Specify the location of the initial ramdisk
890 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
893 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
895 Enable intel iommu driver.
897 Disable intel iommu driver.
898 igfx_off [Default Off]
899 By default, gfx is mapped as normal device. If a gfx
900 device has a dedicated DMAR unit, the DMAR unit is
901 bypassed by not enabling DMAR with this option. In
902 this case, gfx device will use physical address for
905 With this option iommu will not optimize to look
906 for io virtual address below 32 bit forcing dual
907 address cycle on pci bus for cards supporting greater
908 than 32 bit addressing. The default is to look
909 for translation below 32 bit and if not available
910 then look in the higher range.
912 With this option on every unmap_single operation will
913 result in a hardware IOTLB flush operation as opposed
914 to batching them for performance.
918 iomem= Disable strict checking of access to MMIO memory
919 strict regions from userspace.
934 io7= [HW] IO7 for Marvel based alpha systems
935 See comment before marvel_specify_io7 in
936 arch/alpha/kernel/core_marvel.c.
938 io_delay= [X86] I/O delay method
940 Standard port 0x80 based delay
942 Alternate port 0xed based delay (needed on some systems)
944 Simple two microseconds delay
949 See Documentation/filesystems/nfsroot.txt.
951 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
952 See comment before ip2_setup() in
953 drivers/char/ip2/ip2base.c.
955 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
956 See header of drivers/scsi/ips.c.
959 When an interrupt is not handled search all handlers
960 for it. Intended to get systems with badly broken
964 When an interrupt is not handled search all handlers
965 for it. Also check all handlers each timer
966 interrupt. Intended to get systems with badly broken
970 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
972 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
974 <cpu number>,...,<cpu number>
976 <cpu number>-<cpu number>
977 (must be a positive range in ascending order)
979 <cpu number>,...,<cpu number>-<cpu number>
981 This option can be used to specify one or more CPUs
982 to isolate from the general SMP balancing and scheduling
983 algorithms. You can move a process onto or off an
984 "isolated" CPU via the CPU affinity syscalls or cpuset.
985 <cpu number> begins at 0 and the maximum value is
986 "number of CPUs in system - 1".
988 This option is the preferred way to isolate CPUs. The
989 alternative -- manually setting the CPU mask of all
990 tasks in the system -- can cause problems and
991 suboptimal load balancer performance.
995 js= [HW,JOY] Analog joystick
996 See Documentation/input/joystick.txt.
1000 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1001 specifies the amount of memory usable by the kernel
1002 for non-movable allocations. The requested amount is
1003 spread evenly throughout all nodes in the system. The
1004 remaining memory in each node is used for Movable
1005 pages. In the event, a node is too small to have both
1006 kernelcore and Movable pages, kernelcore pages will
1007 take priority and other nodes will have a larger number
1008 of kernelcore pages. The Movable zone is used for the
1009 allocation of pages that may be reclaimed or moved
1010 by the page migration subsystem. This means that
1011 HugeTLB pages may not be allocated from this zone.
1012 Note that allocations like PTEs-from-HighMem still
1013 use the HighMem zone if it exists, and the Normal
1014 zone if it does not.
1016 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1017 Controls whether kmemtrace is enabled
1020 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1021 subbufs kmemtrace's relay channel has. Set this
1022 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1023 you experience buffer overruns.
1025 kgdboc= [HW] kgdb over consoles.
1026 Requires a tty driver that supports console polling.
1027 (only serial suported for now)
1028 Format: <serial_device>[,baud]
1030 kmac= [MIPS] korina ethernet MAC address.
1031 Configure the RouterBoard 532 series on-chip
1032 Ethernet adapter MAC address.
1034 kstack=N [X86] Print N words from the kernel stack
1041 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1044 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1047 libata.dma= [LIBATA] DMA control
1048 libata.dma=0 Disable all PATA and SATA DMA
1049 libata.dma=1 PATA and SATA Disk DMA only
1050 libata.dma=2 ATAPI (CDROM) DMA only
1051 libata.dma=4 Compact Flash DMA only
1052 Combinations also work, so libata.dma=3 enables DMA
1053 for disks and CDROMs, but not CFs.
1055 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1059 libata.force= [LIBATA] Force configurations. The format is comma
1060 separated list of "[ID:]VAL" where ID is
1061 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1062 matching port, link or device. Basically, it matches
1063 the ATA ID string printed on console by libata. If
1064 the whole ID part is omitted, the last PORT and DEVICE
1065 values are used. If ID hasn't been specified yet, the
1066 configuration applies to all ports, links and devices.
1068 If only DEVICE is omitted, the parameter applies to
1069 the port and all links and devices behind it. DEVICE
1070 number of 0 either selects the first device or the
1071 first fan-out link behind PMP device. It does not
1072 select the host link. DEVICE number of 15 selects the
1073 host link and device attached to it.
1075 The VAL specifies the configuration to force. As long
1076 as there's no ambiguity shortcut notation is allowed.
1077 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1078 The following configurations can be forced.
1080 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1081 Any ID with matching PORT is used.
1083 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1085 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1086 udma[/][16,25,33,44,66,100,133] notation is also
1089 * [no]ncq: Turn on or off NCQ.
1091 * nohrst, nosrst, norst: suppress hard, soft
1094 If there are multiple matching configurations changing
1095 the same attribute, the last one is used.
1097 lmb=debug [KNL] Enable lmb debug messages.
1099 load_ramdisk= [RAM] List of ramdisks to load from floppy
1100 See Documentation/blockdev/ramdisk.txt.
1102 lockd.nlm_grace_period=P [NFS] Assign grace period.
1105 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1108 lockd.nlm_timeout=T [NFS] Assign timeout value.
1111 lockd.nlm_udpport=M [NFS] Assign UDP port.
1114 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1117 loglevel= All Kernel Messages with a loglevel smaller than the
1118 console loglevel will be printed to the console. It can
1119 also be changed with klogd or other programs. The
1120 loglevels are defined as follows:
1122 0 (KERN_EMERG) system is unusable
1123 1 (KERN_ALERT) action must be taken immediately
1124 2 (KERN_CRIT) critical conditions
1125 3 (KERN_ERR) error conditions
1126 4 (KERN_WARNING) warning conditions
1127 5 (KERN_NOTICE) normal but significant condition
1128 6 (KERN_INFO) informational
1129 7 (KERN_DEBUG) debug-level messages
1131 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1132 Format: { n | nk | nM }
1133 n must be a power of two. The default size
1134 is set in the kernel config file.
1136 logo.nologo [FB] Disables display of the built-in Linux logo.
1137 This may be used to provide more screen space for
1138 kernel log messages and is useful when debugging
1139 kernel boot problems.
1141 lp=0 [LP] Specify parallel ports to use, e.g,
1142 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1143 lp=reset first parallel port). 'lp=0' disables the
1144 lp=auto printer driver. 'lp=reset' (which can be
1145 specified in addition to the ports) causes
1146 attached printers to be reset. Using
1147 lp=port1,port2,... specifies the parallel ports
1148 to associate lp devices with, starting with
1149 lp0. A port specification may be 'none' to skip
1150 that lp device, or a parport name such as
1151 'parport0'. Specifying 'lp=auto' instead of a
1152 port specification list means that device IDs
1153 from each port should be examined, to see if
1154 an IEEE 1284-compliant printer is attached; if
1155 so, the driver will manage that printer.
1156 See also header of drivers/char/lp.c.
1159 Sets loops_per_jiffy to given constant, thus avoiding
1160 time-consuming boot-time autodetection (up to 250 ms per
1161 CPU). 0 enables autodetection (default). To determine
1162 the correct value for your kernel, boot with normal
1163 autodetection and see what value is printed. Note that
1164 on SMP systems the preset will be applied to all CPUs,
1165 which is likely to cause problems if your CPUs need
1166 significantly divergent settings. An incorrect value
1167 will cause delays in the kernel to be wrong, leading to
1168 unpredictable I/O errors and other breakage. Although
1169 unlikely, in the extreme case this might damage your
1173 Format: <io>,<irq>,<dma>
1175 mac5380= [HW,SCSI] Format:
1176 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1178 machvec= [IA64] Force the use of a particular machine-vector
1179 (machvec) in a generic kernel.
1180 Example: machvec=hpzx1_swiotlb
1182 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1183 than or equal to this physical address is ignored.
1185 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1186 should make use of. maxcpus=n : n >= 0 limits the
1187 kernel to using 'n' processors. n=0 is a special case,
1188 it is equivalent to "nosmp", which also disables
1191 max_loop= [LOOP] Maximum number of loopback devices that can
1195 max_luns= [SCSI] Maximum number of LUNs to probe.
1196 Should be between 1 and 2^32-1.
1199 [SCSI] Maximum number of LUNs received.
1200 Should be between 1 and 16384.
1204 mce [X86-32] Machine Check Exception
1206 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1208 md= [HW] RAID subsystems devices and level
1209 See Documentation/md.txt.
1212 Format: <first>,<last>
1213 Specifies range of consoles to be captured by the MDA.
1215 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1216 Amount of memory to be used when the kernel is not able
1217 to see the whole system memory or for test.
1218 [X86-32] Use together with memmap= to avoid physical
1219 address space collisions. Without memmap= PCI devices
1220 could be placed at addresses belonging to unused RAM.
1222 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1226 [KNL,SH] Allow user to override the default size for
1227 per-device physically contiguous DMA buffers.
1229 memmap=exactmap [KNL,X86] Enable setting of an exact
1230 E820 memory map, as specified by the user.
1231 Such memmap=exactmap lines can be constructed based on
1232 BIOS output or other requirements. See the memmap=nn@ss
1235 memmap=nn[KMG]@ss[KMG]
1236 [KNL] Force usage of a specific region of memory
1237 Region of memory to be used, from ss to ss+nn.
1239 memmap=nn[KMG]#ss[KMG]
1240 [KNL,ACPI] Mark specific memory as ACPI data.
1241 Region of memory to be used, from ss to ss+nn.
1243 memmap=nn[KMG]$ss[KMG]
1244 [KNL,ACPI] Mark specific memory as reserved.
1245 Region of memory to be used, from ss to ss+nn.
1246 Example: Exclude memory from 0x18690000-0x1869ffff
1247 memmap=64K$0x18690000
1249 memmap=0x10000$0x18690000
1251 memory_corruption_check=0/1 [X86]
1252 Some BIOSes seem to corrupt the first 64k of
1253 memory when doing things like suspend/resume.
1254 Setting this option will scan the memory
1255 looking for corruption. Enabling this will
1256 both detect corruption and prevent the kernel
1257 from using the memory being corrupted.
1258 However, its intended as a diagnostic tool; if
1259 repeatable BIOS-originated corruption always
1260 affects the same memory, you can use memmap=
1261 to prevent the kernel from using that memory.
1263 memory_corruption_check_size=size [X86]
1264 By default it checks for corruption in the low
1265 64k, making this memory unavailable for normal
1266 use. Use this parameter to scan for
1267 corruption in more or less memory.
1269 memory_corruption_check_period=seconds [X86]
1270 By default it checks for corruption every 60
1271 seconds. Use this parameter to check at some
1272 other rate. 0 disables periodic checking.
1274 memtest= [KNL,X86] Enable memtest
1276 default : 0 <disable>
1277 Specifies the number of memtest passes to be
1278 performed. Each pass selects another test
1279 pattern from a given set of patterns. Memtest
1280 fills the memory with this pattern, validates
1281 memory contents and reserves bad memory
1282 regions that are detected.
1284 meye.*= [HW] Set MotionEye Camera parameters
1285 See Documentation/video4linux/meye.txt.
1287 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1288 Multi-Function General Purpose Timers on AMD Geode
1291 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1292 the BIOS has incorrectly applied a workaround. TinyBIOS
1293 version 0.98 is known to be affected, 0.99 fixes the
1294 problem by letting the user disable the workaround.
1298 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1299 physical address is ignored.
1302 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1303 parameter allows control of the logging verbosity for
1304 the additional memory initialisation checks. A value
1305 of 0 disables mminit logging and a level of 4 will
1306 log everything. Information is printed at KERN_DEBUG
1307 so loglevel=8 may also need to be specified.
1310 [MOUSE] Maximum time between finger touching and
1311 leaving touchpad surface for touch to be considered
1312 a tap and be reported as a left button click (for
1313 touchpads working in absolute mode only).
1315 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1316 reporting absolute coordinates, such as tablets
1317 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1318 reporting absolute coordinates, such as tablets
1320 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1321 is similar to kernelcore except it specifies the
1322 amount of memory used for migratable allocations.
1323 If both kernelcore and movablecore is specified,
1324 then kernelcore will be at *least* the specified
1325 value but may be more. If movablecore on its own
1326 is specified, the administrator must be careful
1327 that the amount of memory usable for all allocations
1333 MTD_Partition= [MTD]
1334 Format: <name>,<region-number>,<size>,<offset>
1336 MTD_Region= [MTD] Format:
1337 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1340 See drivers/mtd/cmdlinepart.c.
1343 ARM/S3C2412 JIVE boot control
1345 See arch/arm/mach-s3c2412/mach-jive.c
1347 mtouchusb.raw_coordinates=
1348 [HW] Make the MicroTouch USB driver use raw coordinates
1349 ('y', default) or cooked coordinates ('n')
1351 mtrr_chunk_size=nn[KMG] [X86]
1352 used for mtrr cleanup. It is largest continous chunk
1353 that could hold holes aka. UC entries.
1355 mtrr_gran_size=nn[KMG] [X86]
1356 Used for mtrr cleanup. It is granularity of mtrr block.
1358 Large value could prevent small alignment from
1361 mtrr_spare_reg_nr=n [X86]
1363 Range: 0,7 : spare reg number
1365 Used for mtrr cleanup. It is spare mtrr entries number.
1366 Set to 2 or more if your graphical card needs more.
1368 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1371 See header of drivers/scsi/NCR_D700.c.
1375 ncr53c400= [HW,SCSI]
1377 ncr53c400a= [HW,SCSI]
1379 ncr53c406a= [HW,SCSI]
1381 ncr53c8xx= [HW,SCSI]
1383 netdev= [NET] Network devices parameters
1384 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1385 Note that mem_start is often overloaded to mean
1386 something different and driver-specific.
1387 This usage is only documented in each driver source
1391 [NETFILTER] Enable connection tracking flow accounting
1392 0 to disable accounting
1393 1 to enable accounting
1394 Default value depends on CONFIG_NF_CT_ACCT that is
1395 going to be removed in 2.6.29.
1398 See Documentation/filesystems/nfsroot.txt.
1400 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1401 See Documentation/filesystems/nfsroot.txt.
1403 nfs.callback_tcpport=
1404 [NFS] set the TCP port on which the NFSv4 callback
1405 channel should listen.
1407 nfs.idmap_cache_timeout=
1408 [NFS] set the maximum lifetime for idmapper cache
1412 [NFS] enable 64-bit inode numbers.
1413 If zero, the NFS client will fake up a 32-bit inode
1414 number for the readdir() and stat() syscalls instead
1415 of returning the full 64-bit number.
1416 The default is to return 64-bit inode numbers.
1418 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1419 when a NMI is triggered.
1420 Format: [state][,regs][,debounce][,die]
1422 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1423 Format: [panic,][num]
1425 0 - turn nmi_watchdog off
1426 1 - use the IO-APIC timer for the NMI watchdog
1427 2 - use the local APIC for the NMI watchdog using
1428 a performance counter. Note: This will use one
1429 performance counter and the local APIC's performance
1431 When panic is specified, panic when an NMI watchdog
1433 This is useful when you use a panic=... timeout and
1434 need the box quickly up again.
1435 Instead of 1 and 2 it is possible to use the following
1436 symbolic names: lapic and ioapic
1437 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1439 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1440 emulation library even if a 387 maths coprocessor
1444 [HW] Never suspend the console
1445 Disable suspending of consoles during suspend and
1446 hibernate operations. Once disabled, debugging
1447 messages can reach various consoles while the rest
1448 of the system is being put to sleep (ie, while
1449 debugging driver suspend/resume hooks). This may
1450 not work reliably with all consoles, but is known
1451 to work with serial and VGA consoles.
1453 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1454 caches in the slab allocator. Saves per-node memory,
1455 but will impact performance.
1459 noapic [SMP,APIC] Tells the kernel to not make use of any
1460 IOAPICs that may be present in the system.
1462 nobats [PPC] Do not use BATs for mapping kernel lowmem
1463 on "Classic" PPC cores.
1467 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1469 nodelayacct [KNL] Disable per-task delay accounting
1471 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1473 nodsp [SH] Disable hardware DSP at boot time.
1475 noefi [X86] Disable EFI runtime services support.
1480 On X86-32 available only on PAE configured kernels.
1481 noexec=on: enable non-executable mappings (default)
1482 noexec=off: disable non-executable mappings
1485 This affects only 32-bit executables.
1486 noexec32=on: enable non-executable mappings (default)
1487 read doesn't imply executable mappings
1488 noexec32=off: disable non-executable mappings
1489 read implies executable mappings
1491 nofpu [SH] Disable hardware FPU at boot time.
1493 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1494 register save and restore. The kernel will only save
1495 legacy floating-point registers on task switch.
1497 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1498 wfi(ARM) instruction doesn't work correctly and not to
1499 use it. This is also useful when using JTAG debugger.
1501 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1502 instruction doesn't work correctly and not to
1505 no_file_caps Tells the kernel not to honor file capabilities. The
1506 only way then for a file to be executed with privilege
1507 is to be setuid root or executed by root.
1509 nohalt [IA-64] Tells the kernel not to use the power saving
1510 function PAL_HALT_LIGHT when idle. This increases
1511 power-consumption. On the positive side, it reduces
1512 interrupt wake-up latency, which may improve performance
1513 in certain environments such as networked servers or
1516 nohz= [KNL] Boottime enable/disable dynamic ticks
1517 Valid arguments: on, off
1520 noiotrap [SH] Disables trapped I/O port accesses.
1522 noirqdebug [X86-32] Disables the code which attempts to detect and
1523 disable unhandled interrupt sources.
1525 no_timer_check [X86,APIC] Disables the code which tests for
1526 broken timer IRQ sources.
1528 noisapnp [ISAPNP] Disables ISA PnP code.
1530 noinitrd [RAM] Tells the kernel not to load any configured
1535 nojitter [IA64] Disables jitter checking for ITC timers.
1537 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1539 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1541 noltlbs [PPC] Do not use large page/tlb entries for kernel
1542 lowmem mapping on PPC40x.
1544 nomca [IA-64] Disable machine check abort handling
1546 nomce [X86-32] Machine Check Exception
1548 nomfgpt [X86-32] Disable Multi-Function General Purpose
1549 Timer usage (for AMD Geode machines).
1551 norandmaps Don't use address space randomization. Equivalent to
1552 echo 0 > /proc/sys/kernel/randomize_va_space
1554 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1556 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1557 with UP alternatives
1559 noresidual [PPC] Don't use residual data on PReP machines.
1561 noresume [SWSUSP] Disables resume and restores original swap
1564 no-scroll [VGA] Disables scrollback.
1565 This is required for the Braillex ib80-piezo Braille
1566 reader made by F.H. Papenmeier (Germany).
1570 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1572 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1573 and disable the IO APIC. legacy for "maxcpus=0".
1575 nosoftlockup [KNL] Disable the soft-lockup detector.
1577 noswapaccount [KNL] Disable accounting of swap in memory resource
1578 controller. (See Documentation/cgroups/memory.txt)
1580 nosync [HW,M68K] Disables sync negotiation for all devices.
1582 notsc [BUGS=X86-32] Disable Time Stamp Counter
1584 nousb [USB] Disable the USB subsystem
1588 nptcg= [IA64] Override max number of concurrent global TLB
1589 purges which is reported from either PAL_VM_SUMMARY or
1592 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1594 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1595 one of ['zone', 'node', 'default'] can be specified
1596 This can be set from sysctl after boot.
1597 See Documentation/sysctl/vm.txt for details.
1599 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1600 See Documentation/debugging-via-ohci1394.txt for more
1603 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1604 Rather than timing out after 20 ms if an EC
1605 command is not properly ACKed, override the length
1606 of the timeout. We have interrupts disabled while
1607 waiting for the ACK, so if this is set too high
1608 interrupts *may* be lost!
1613 oprofile.timer= [HW]
1614 Use timer interrupt instead of performance counters
1616 osst= [HW,SCSI] SCSI Tape Driver
1617 Format: <buffer_size>,<write_threshold>
1618 See also Documentation/scsi/st.txt.
1620 panic= [KNL] Kernel behaviour on panic
1623 parkbd.port= [HW] Parallel port number the keyboard adapter is
1624 connected to, default is 0.
1626 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1627 0 for XT, 1 for AT (default is AT).
1630 parport= [HW,PPT] Specify parallel ports. 0 disables.
1631 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1632 Use 'auto' to force the driver to use any
1633 IRQ/DMA settings detected (the default is to
1634 ignore detected IRQ/DMA settings because of
1635 possible conflicts). You can specify the base
1636 address, IRQ, and DMA settings; IRQ and DMA
1637 should be numbers, or 'auto' (for using detected
1638 settings on that particular port), or 'nofifo'
1639 (to avoid using a FIFO even if it is detected).
1640 Parallel ports are assigned in the order they
1641 are specified on the command line, starting
1644 parport_init_mode= [HW,PPT]
1645 Configure VIA parallel port to operate in
1646 a specific mode. This is necessary on Pegasos
1647 computer where firmware has no options for setting
1648 up parallel port mode and sets it to spp.
1649 Currently this function knows 686a and 8231 chips.
1650 Format: [spp|ps2|epp|ecp|ecpepp]
1652 pas2= [HW,OSS] Format:
1653 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1656 See header of drivers/scsi/pas16.c.
1659 Halt all CPUs after the first oops has been printed for
1660 the specified number of seconds. This is to be used if
1661 your oopses keep scrolling off the screen.
1666 See header of drivers/block/paride/pcd.c.
1667 See also Documentation/blockdev/paride.txt.
1669 pci=option[,option...] [PCI] various PCI subsystem options:
1670 earlydump [X86] dump PCI config space before the kernel
1672 off [X86] don't probe for the PCI bus
1673 bios [X86-32] force use of PCI BIOS, don't access
1674 the hardware directly. Use this if your machine
1675 has a non-standard PCI host bridge.
1676 nobios [X86-32] disallow use of PCI BIOS, only direct
1677 hardware access methods are allowed. Use this
1678 if you experience crashes upon bootup and you
1679 suspect they are caused by the BIOS.
1680 conf1 [X86] Force use of PCI Configuration
1682 conf2 [X86] Force use of PCI Configuration
1684 noaer [PCIE] If the PCIEAER kernel config parameter is
1685 enabled, this kernel boot option can be used to
1686 disable the use of PCIE advanced error reporting.
1687 nodomains [PCI] Disable support for multiple PCI
1688 root domains (aka PCI segments, in ACPI-speak).
1689 nommconf [X86] Disable use of MMCONFIG for PCI
1691 nomsi [MSI] If the PCI_MSI kernel config parameter is
1692 enabled, this kernel boot option can be used to
1693 disable the use of MSI interrupts system-wide.
1694 noioapicquirk [APIC] Disable all boot interrupt quirks.
1695 Safety option to keep boot IRQs enabled. This
1696 should never be necessary.
1697 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1698 primary IO-APIC for bridges that cannot disable
1699 boot IRQs. This fixes a source of spurious IRQs
1700 when the system masks IRQs.
1701 noioapicreroute [APIC] Disable workaround that uses the
1702 boot IRQ equivalent of an IRQ that connects to
1703 a chipset where boot IRQs cannot be disabled.
1704 The opposite of ioapicreroute.
1705 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1706 routing table. These calls are known to be buggy
1707 on several machines and they hang the machine
1708 when used, but on other computers it's the only
1709 way to get the interrupt routing table. Try
1710 this option if the kernel is unable to allocate
1711 IRQs or discover secondary PCI buses on your
1713 rom [X86] Assign address space to expansion ROMs.
1714 Use with caution as certain devices share
1715 address decoders between ROMs and other
1717 norom [X86] Do not assign address space to
1718 expansion ROMs that do not already have
1719 BIOS assigned address ranges.
1720 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1721 assigned automatically to PCI devices. You can
1722 make the kernel exclude IRQs of your ISA cards
1724 pirqaddr=0xAAAAA [X86] Specify the physical address
1725 of the PIRQ table (normally generated
1726 by the BIOS) if it is outside the
1727 F0000h-100000h range.
1728 lastbus=N [X86] Scan all buses thru bus #N. Can be
1729 useful if the kernel is unable to find your
1730 secondary buses and you want to tell it
1731 explicitly which ones they are.
1732 assign-busses [X86] Always assign all PCI bus
1733 numbers ourselves, overriding
1734 whatever the firmware may have done.
1735 usepirqmask [X86] Honor the possible IRQ mask stored
1736 in the BIOS $PIR table. This is needed on
1737 some systems with broken BIOSes, notably
1738 some HP Pavilion N5400 and Omnibook XE3
1739 notebooks. This will have no effect if ACPI
1740 IRQ routing is enabled.
1741 noacpi [X86] Do not use ACPI for IRQ routing
1742 or for PCI scanning.
1743 use_crs [X86] Use _CRS for PCI resource
1745 routeirq Do IRQ routing for all PCI devices.
1746 This is normally done in pci_enable_device(),
1747 so this option is a temporary workaround
1748 for broken drivers that don't call it.
1749 skip_isa_align [X86] do not align io start addr, so can
1750 handle more pci cards
1751 firmware [ARM] Do not re-enumerate the bus but instead
1752 just use the configuration from the
1753 bootloader. This is currently used on
1754 IXP2000 systems where the bus has to be
1755 configured a certain way for adjunct CPUs.
1756 noearly [X86] Don't do any early type 1 scanning.
1757 This might help on some broken boards which
1758 machine check when some devices' config space
1759 is read. But various workarounds are disabled
1760 and some IOMMU drivers will not work.
1761 bfsort Sort PCI devices into breadth-first order.
1762 This sorting is done to get a device
1763 order compatible with older (<= 2.4) kernels.
1764 nobfsort Don't sort PCI devices into breadth-first order.
1765 cbiosize=nn[KMG] The fixed amount of bus space which is
1766 reserved for the CardBus bridge's IO window.
1767 The default value is 256 bytes.
1768 cbmemsize=nn[KMG] The fixed amount of bus space which is
1769 reserved for the CardBus bridge's memory
1770 window. The default value is 64 megabytes.
1773 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1774 Specifies alignment and device to reassign
1775 aligned memory resources.
1776 If <order of align> is not specified,
1777 PAGE_SIZE is used as alignment.
1778 PCI-PCI bridge can be specified, if resource
1779 windows need to be expanded.
1781 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1784 force Enable ASPM even on devices that claim not to support it.
1785 WARNING: Forcing ASPM on may cause system lockups.
1787 pcmv= [HW,PCMCIA] BadgePAD 4
1790 See Documentation/blockdev/paride.txt.
1792 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1795 See arch/parisc/kernel/pdc_chassis.c
1798 See Documentation/blockdev/paride.txt.
1801 See Documentation/blockdev/paride.txt.
1803 pirq= [SMP,APIC] Manual mp-table setup
1804 See Documentation/x86/i386/IO-APIC.txt.
1806 plip= [PPT,NET] Parallel port network link
1807 Format: { parport<nr> | timid | 0 }
1808 See also Documentation/parport.txt.
1810 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1811 Override pmtimer IOPort with a hex value.
1815 Enable PNP debug messages. This depends on the
1816 CONFIG_PNP_DEBUG_MESSAGES option.
1822 { on | off | curr | res | no-curr | no-res }
1825 [ISAPNP] Exclude IRQs for the autoconfiguration
1828 [ISAPNP] Exclude DMAs for the autoconfiguration
1830 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1831 Ranges are in pairs (I/O port base and size).
1834 [ISAPNP] Exclude memory regions for the
1836 Ranges are in pairs (memory base and size).
1838 print-fatal-signals=
1839 [KNL] debug: print fatal signals
1840 print-fatal-signals=1: print segfault info to
1844 printk.time= Show timing data prefixed to each printk message line
1845 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1847 processor.max_cstate= [HW,ACPI]
1848 Limit processor to maximum C-state
1849 max_cstate=9 overrides any DMI blacklist limit.
1851 processor.nocst [HW,ACPI]
1852 Ignore the _CST method to determine C-states,
1853 instead using the legacy FADT method
1855 profile= [KNL] Enable kernel profiling via /proc/profile
1856 Format: [schedule,]<number>
1857 Param: "schedule" - profile schedule points.
1858 Param: <number> - step/bucket size as a power of 2 for
1859 statistical time based profiling.
1860 Param: "sleep" - profile D-state sleeping (millisecs).
1861 Requires CONFIG_SCHEDSTATS
1862 Param: "kvm" - profile VM exits.
1864 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1866 See Documentation/blockdev/ramdisk.txt.
1868 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1869 probe for; one of (bare|imps|exps|lifebook|any).
1870 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1872 psmouse.resetafter= [HW,MOUSE]
1873 Try to reset the device after so many bad packets
1876 [HW,MOUSE] Set desired mouse resolution, in dpi.
1877 psmouse.smartscroll=
1878 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1879 0 = disabled, 1 = enabled (default).
1881 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1883 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1886 See Documentation/blockdev/paride.txt.
1889 [KNL] Number of legacy pty's. Overwrites compiled-in
1892 quiet [KNL] Disable most log messages
1897 See Documentation/md.txt.
1899 ramdisk_blocksize= [RAM]
1900 See Documentation/blockdev/ramdisk.txt.
1902 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1903 See Documentation/blockdev/ramdisk.txt.
1905 rcupdate.blimit= [KNL,BOOT]
1906 Set maximum number of finished RCU callbacks to process
1909 rcupdate.qhimark= [KNL,BOOT]
1910 Set threshold of queued
1911 RCU callbacks over which batch limiting is disabled.
1913 rcupdate.qlowmark= [KNL,BOOT]
1914 Set threshold of queued RCU callbacks below which
1915 batch limiting is re-enabled.
1919 Run specified binary instead of /init from the ramdisk,
1920 used for early userspace startup. See initrd.
1922 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1923 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1924 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1927 [KNL, SMP] Set scheduler's default relax_domain_level.
1928 See Documentation/cgroups/cpusets.txt.
1930 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1932 reservetop= [X86-32]
1934 Reserves a hole at the top of the kernel virtual
1937 reset_devices [KNL] Force drivers to reset the underlying device
1938 during initialization.
1941 Specify the partition device for software suspend
1943 resume_offset= [SWSUSP]
1944 Specify the offset from the beginning of the partition
1945 given by "resume=" at which the swap header is located,
1946 in <PAGE_SIZE> units (needed only for swap files).
1947 See Documentation/power/swsusp-and-swap-files.txt
1949 retain_initrd [RAM] Keep initrd memory after extraction
1951 rhash_entries= [KNL,NET]
1952 Set number of hash buckets for route cache
1954 riscom8= [HW,SERIAL]
1955 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1957 ro [KNL] Mount root device read-only on boot
1959 root= [KNL] Root filesystem
1961 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1962 mount the root filesystem
1964 rootflags= [KNL] Set root filesystem mount option string
1966 rootfstype= [KNL] Set root filesystem type
1968 rootwait [KNL] Wait (indefinitely) for root device to show up.
1969 Useful for devices that are detected asynchronously
1970 (e.g. USB and MMC devices).
1972 root_plug.vendor_id=
1973 [ROOTPLUG] Override the default vendor ID
1975 root_plug.product_id=
1976 [ROOTPLUG] Override the default product ID
1979 [ROOTPLUG] Enable debugging output
1981 rw [KNL] Mount root device read-write on boot
1983 S [KNL] Run init in single mode
1986 See drivers/net/irda/sa1100_ir.c.
1988 sbni= [NET] Granch SBNI12 leased line adapter
1990 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1991 Format: <io>[,<timeout>[,<isapnp>]]
1993 scsi_debug_*= [SCSI]
1994 See drivers/scsi/scsi_debug.c.
1996 scsi_default_dev_flags=
1997 [SCSI] SCSI default device flags
2000 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2001 Format: <vendor>:<model>:<flags>
2002 (flags are integer value)
2004 scsi_logging_level= [SCSI] a bit mask of logging levels
2005 See drivers/scsi/scsi_logging.h for bits. Also
2006 settable via sysctl at dev.scsi.logging_level
2007 (/proc/sys/dev/scsi/logging_level).
2008 There is also a nice 'scsi_logging_level' script in the
2009 S390-tools package, available for download at
2010 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2012 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2013 discovered. async scans them in kernel threads,
2014 allowing boot to proceed. none ignores them, expecting
2015 user space to do the scan.
2017 security= [SECURITY] Choose a security module to enable at boot.
2018 If this boot parameter is not specified, only the first
2019 security module asking for security registration will be
2020 loaded. An invalid security module name will be treated
2021 as if no module has been chosen.
2023 selinux= [SELINUX] Disable or enable SELinux at boot time.
2024 Format: { "0" | "1" }
2025 See security/selinux/Kconfig help text.
2028 Default value is set via kernel config option.
2029 If enabled at boot time, /selinux/disable can be used
2030 later to disable prior to initial policy load.
2032 serialnumber [BUGS=X86-32]
2035 Maximal number of shapers.
2037 show_msr= [x86] show boot-time MSR settings
2038 Format: { <integer> }
2039 Show boot-time (BIOS-initialized) MSR settings.
2040 The parameter means the number of CPUs to show,
2041 for example 1 means boot CPU only.
2044 See header of drivers/scsi/sim710.c.
2051 slub_debug[=options[,slabs]] [MM, SLUB]
2052 Enabling slub_debug allows one to determine the
2053 culprit if slab objects become corrupted. Enabling
2054 slub_debug can create guard zones around objects and
2055 may poison objects when not in use. Also tracks the
2056 last alloc / free. For more information see
2057 Documentation/vm/slub.txt.
2059 slub_max_order= [MM, SLUB]
2060 Determines the maximum allowed order for slabs.
2061 A high setting may cause OOMs due to memory
2062 fragmentation. For more information see
2063 Documentation/vm/slub.txt.
2065 slub_min_objects= [MM, SLUB]
2066 The minimum number of objects per slab. SLUB will
2067 increase the slab order up to slub_max_order to
2068 generate a sufficiently large slab able to contain
2069 the number of objects indicated. The higher the number
2070 of objects the smaller the overhead of tracking slabs
2071 and the less frequently locks need to be acquired.
2072 For more information see Documentation/vm/slub.txt.
2074 slub_min_order= [MM, SLUB]
2075 Determines the mininum page order for slabs. Must be
2076 lower than slub_max_order.
2077 For more information see Documentation/vm/slub.txt.
2079 slub_nomerge [MM, SLUB]
2080 Disable merging of slabs with similar size. May be
2081 necessary if there is some reason to distinguish
2082 allocs to different slabs. Debug options disable
2083 merging on their own.
2084 For more information see Documentation/vm/slub.txt.
2087 Format: <io1>[,<io2>[,...,<io8>]]
2089 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2090 attempt to substitute SMP alternatives once at boot.
2092 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2093 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2094 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2095 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2096 smsc-ircc2.ircc_irq= [HW] IRQ line
2097 smsc-ircc2.ircc_dma= [HW] DMA channel
2098 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2099 0: Toshiba Satellite 1800 (GP data pin select)
2100 1: Fast pin select (default)
2103 snd-ad1816a= [HW,ALSA]
2105 snd-ad1848= [HW,ALSA]
2107 snd-ali5451= [HW,ALSA]
2109 snd-als100= [HW,ALSA]
2111 snd-als4000= [HW,ALSA]
2113 snd-azt2320= [HW,ALSA]
2115 snd-cmi8330= [HW,ALSA]
2117 snd-cmipci= [HW,ALSA]
2119 snd-cs4231= [HW,ALSA]
2121 snd-cs4232= [HW,ALSA]
2123 snd-cs4236= [HW,ALSA]
2125 snd-cs4281= [HW,ALSA]
2127 snd-cs46xx= [HW,ALSA]
2129 snd-dt019x= [HW,ALSA]
2131 snd-dummy= [HW,ALSA]
2133 snd-emu10k1= [HW,ALSA]
2135 snd-ens1370= [HW,ALSA]
2137 snd-ens1371= [HW,ALSA]
2139 snd-es968= [HW,ALSA]
2141 snd-es1688= [HW,ALSA]
2143 snd-es18xx= [HW,ALSA]
2145 snd-es1938= [HW,ALSA]
2147 snd-es1968= [HW,ALSA]
2149 snd-fm801= [HW,ALSA]
2151 snd-gusclassic= [HW,ALSA]
2153 snd-gusextreme= [HW,ALSA]
2155 snd-gusmax= [HW,ALSA]
2159 snd-ice1712= [HW,ALSA]
2161 snd-intel8x0= [HW,ALSA]
2163 snd-interwave= [HW,ALSA]
2168 snd-korg1212= [HW,ALSA]
2170 snd-maestro3= [HW,ALSA]
2172 snd-mpu401= [HW,ALSA]
2174 snd-mtpav= [HW,ALSA]
2176 snd-nm256= [HW,ALSA]
2178 snd-opl3sa2= [HW,ALSA]
2186 snd-opti93x= [HW,ALSA]
2190 snd-rme32= [HW,ALSA]
2192 snd-rme96= [HW,ALSA]
2194 snd-rme9652= [HW,ALSA]
2200 snd-sbawe= [HW,ALSA]
2202 snd-serial= [HW,ALSA]
2204 snd-sgalaxy= [HW,ALSA]
2206 snd-sonicvibes= [HW,ALSA]
2211 snd-sun-cs4231= [HW,ALSA]
2213 snd-trident= [HW,ALSA]
2215 snd-usb-audio= [HW,ALSA,USB]
2217 snd-via82xx= [HW,ALSA]
2219 snd-virmidi= [HW,ALSA]
2221 snd-wavefront= [HW,ALSA]
2223 snd-ymfpci= [HW,ALSA]
2226 [KNL] Should the soft-lockup detector generate panics.
2228 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2229 See Documentation/sonypi.txt
2231 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2232 See Documentation/serial/specialix.txt.
2234 spia_io_base= [HW,MTD]
2240 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2242 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2243 See Documentation/scsi/st.txt.
2246 Enabled the stack tracer on boot up.
2250 Set the STI (builtin display/keyboard on the HP-PARISC
2251 machines) console (graphic card) which should be used
2252 as the initial boot-console.
2253 See also comment in drivers/video/console/sticore.c.
2256 See comment in drivers/video/console/sticore.c.
2259 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2263 Control how the NFS server code allocates CPUs to
2264 service thread pools. Depending on how many NICs
2265 you have and where their interrupts are bound, this
2266 option will affect which CPUs will do NFS serving.
2267 Note: this parameter cannot be changed while the
2268 NFS server is running.
2270 auto the server chooses an appropriate mode
2271 automatically using heuristics
2272 global a single global pool contains all CPUs
2273 percpu one pool for each CPU
2274 pernode one pool for each NUMA node (equivalent
2275 to global on non-NUMA machines)
2277 swiotlb= [IA-64] Number of I/O TLB slabs
2281 sym53c416= [HW,SCSI]
2282 See header of drivers/scsi/sym53c416.c.
2284 sysrq_always_enabled
2286 Ignore sysrq setting - this boot parameter will
2287 neutralize any effect of /proc/sys/kernel/sysrq.
2288 Useful for debugging.
2291 See header of drivers/scsi/t128.c.
2295 test_suspend= [SUSPEND]
2296 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2297 standby suspend) as the system sleep state to briefly
2298 enter during system startup. The system is woken from
2299 this state using a wakeup-capable RTC alarm.
2301 thash_entries= [KNL,NET]
2302 Set number of hash buckets for TCP connection
2304 thermal.act= [HW,ACPI]
2305 -1: disable all active trip points in all thermal zones
2306 <degrees C>: override all lowest active trip points
2308 thermal.crt= [HW,ACPI]
2309 -1: disable all critical trip points in all thermal zones
2310 <degrees C>: override all critical trip points
2312 thermal.nocrt= [HW,ACPI]
2313 Set to disable actions on ACPI thermal zone
2314 critical and hot trip points.
2316 thermal.off= [HW,ACPI]
2317 1: disable ACPI thermal control
2319 thermal.psv= [HW,ACPI]
2320 -1: disable all passive trip points
2321 <degrees C>: override all passive trip points to this
2324 thermal.tzp= [HW,ACPI]
2325 Specify global default ACPI thermal zone polling rate
2326 <deci-seconds>: poll all this frequency
2327 0: no polling (default)
2330 See comment before function dc390_setup() in
2331 drivers/scsi/tmscsim.c.
2335 Specify if the kernel should make use of the cpu
2336 topology informations if the hardware supports these.
2337 The scheduler will make use of these informations and
2338 e.g. base its process migration decisions on it.
2343 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2345 trix= [HW,OSS] MediaTrix AudioTrix Pro
2347 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2349 tsc= Disable clocksource-must-verify flag for TSC.
2351 [x86] reliable: mark tsc clocksource as reliable, this
2352 disables clocksource verification at runtime.
2353 Used to enable high-resolution timer mode on older
2354 hardware, and in virtualized environment.
2356 turbografx.map[2|3]= [HW,JOY]
2357 TurboGraFX parallel port interface
2359 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2360 See also Documentation/input/joystick-parport.txt
2362 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2363 See header of drivers/scsi/u14-34f.c.
2372 [USB] Ignore overcurrent events (default N).
2373 Some badly-designed motherboards generate lots of
2374 bogus events, for ports that aren't wired to
2375 anything. Set this parameter to avoid log spamming.
2376 Note that genuine overcurrent events won't be
2381 Set unknown_nmi_panic=1 early on boot.
2383 usbcore.autosuspend=
2384 [USB] The autosuspend time delay (in seconds) used
2385 for newly-detected USB devices (default 2). This
2386 is the time required before an idle device will be
2387 autosuspended. Devices for which the delay is set
2388 to a negative value won't be autosuspended at all.
2390 usbcore.usbfs_snoop=
2391 [USB] Set to log all usbfs traffic (default 0 = off).
2393 usbcore.blinkenlights=
2394 [USB] Set to cycle leds on hubs (default 0 = off).
2396 usbcore.old_scheme_first=
2397 [USB] Start with the old device initialization
2398 scheme (default 0 = off).
2400 usbcore.use_both_schemes=
2401 [USB] Try the other device initialization scheme
2402 if the first one fails (default 1 = enabled).
2404 usbcore.initial_descriptor_timeout=
2405 [USB] Specifies timeout for the initial 64-byte
2406 USB_REQ_GET_DESCRIPTOR request in milliseconds
2407 (default 5000 = 5.0 seconds).
2410 [USBHID] The interval which mice are to be polled at.
2412 usb-storage.delay_use=
2413 [UMS] The delay in seconds before a new device is
2414 scanned for Logical Units (default 5).
2417 [UMS] A list of quirks entries to supplement or
2418 override the built-in unusual_devs list. List
2419 entries are separated by commas. Each entry has
2420 the form VID:PID:Flags where VID and PID are Vendor
2421 and Product ID values (4-digit hex numbers) and
2422 Flags is a set of characters, each corresponding
2423 to a common usb-storage quirk flag as follows:
2424 a = SANE_SENSE (collect more than 18 bytes
2426 c = FIX_CAPACITY (decrease the reported
2427 device capacity by one sector);
2428 h = CAPACITY_HEURISTICS (decrease the
2429 reported device capacity by one
2430 sector if the number is odd);
2431 i = IGNORE_DEVICE (don't bind to this
2433 l = NOT_LOCKABLE (don't try to lock and
2434 unlock ejectable media);
2435 m = MAX_SECTORS_64 (don't transfer more
2436 than 64 sectors = 32 KB at a time);
2437 o = CAPACITY_OK (accept the capacity
2438 reported by the device);
2439 r = IGNORE_RESIDUE (the device reports
2440 bogus residue values);
2441 s = SINGLE_LUN (the device has only one
2443 w = NO_WP_DETECT (don't test whether the
2444 medium is write-protected).
2445 Example: quirks=0419:aaf5:rl,0421:0433:rc
2448 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2449 vdso=1: enable VDSO (default)
2450 vdso=0: disable VDSO mapping
2453 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2454 vdso32=1: enable 32-bit VDSO (default)
2455 vdso32=0: disable 32-bit VDSO mapping
2458 vector=percpu: enable percpu vector domain
2460 video= [FB] Frame buffer configuration
2461 See Documentation/fb/modedb.txt.
2463 vga= [BOOT,X86-32] Select a particular video mode
2464 See Documentation/x86/boot.txt and
2465 Documentation/svga.txt.
2466 Use vga=ask for menu.
2467 This is actually a boot loader parameter; the value is
2468 passed to the kernel using a special protocol.
2470 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2471 size of <nn>. This can be used to increase the
2472 minimum size (128MB on x86). It can also be used to
2473 decrease the size and leave more room for directly
2476 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2479 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2482 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2485 vt.default_blu= [VT]
2486 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2487 Change the default blue palette of the console.
2488 This is a 16-member array composed of values
2491 vt.default_grn= [VT]
2492 Format: <green0>,<green1>,<green2>,...,<green15>
2493 Change the default green palette of the console.
2494 This is a 16-member array composed of values
2497 vt.default_red= [VT]
2498 Format: <red0>,<red1>,<red2>,...,<red15>
2499 Change the default red palette of the console.
2500 This is a 16-member array composed of values
2506 Set system-wide default UTF-8 mode for all tty's.
2507 Default is 1, i.e. UTF-8 mode is enabled for all
2508 newly opened terminals.
2510 waveartist= [HW,OSS]
2511 Format: <io>,<irq>,<dma>,<dma2>
2514 See header of drivers/scsi/wd33c93.c.
2517 See header of drivers/scsi/wd7000.c.
2520 See Documentation/watchdog/wdt.txt.
2522 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2523 default x2apic cluster mode on platforms
2526 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2527 xd_geo= See header of drivers/block/xd.c.
2529 xirc2ps_cs= [NET,PCMCIA]
2531 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2533 ______________________________________________________________________
2537 Add documentation for ALSA options.
2538 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob