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 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
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 IPV6 IPv6 support is enabled.
58 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
61 KGDB Kernel debugger support is enabled.
62 KVM Kernel Virtual Machine support is enabled.
63 LIBATA Libata driver is enabled
64 LP Printer support is enabled.
65 LOOP Loopback device support is enabled.
66 M68k M68k architecture is enabled.
67 These options have more detailed description inside of
68 Documentation/m68k/kernel-options.txt.
69 MCA MCA bus support is enabled.
70 MDA MDA console support is enabled.
71 MOUSE Appropriate mouse support is enabled.
72 MSI Message Signaled Interrupts (PCI).
73 MTD MTD (Memory Technology Device) support is enabled.
74 NET Appropriate network support is enabled.
75 NUMA NUMA support is enabled.
76 GENERIC_TIME The generic timeofday code is enabled.
77 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
79 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
81 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
83 PCIE PCI Express support is enabled.
84 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers has their options described inside of
94 SECURITY Different security models are enabled.
95 SELINUX SELinux support is enabled.
96 APPARMOR AppArmor support is enabled.
97 SERIAL Serial support is enabled.
98 SH SuperH architecture is enabled.
99 SMP The kernel is an SMP kernel.
100 SPARC Sparc architecture is enabled.
101 SWSUSP Software suspend (hibernation) is enabled.
102 SUSPEND System suspend states are enabled.
103 FTRACE Function tracing enabled.
104 TPM TPM drivers are enabled.
105 TS Appropriate touchscreen support is enabled.
106 UMS USB Mass Storage support is enabled.
107 USB USB support is enabled.
108 USBHID USB Human Interface Device support is enabled.
109 V4L Video For Linux support is enabled.
110 VGA The VGA console has been enabled.
111 VT Virtual terminal support is enabled.
112 WDT Watchdog support is enabled.
113 XT IBM PC/XT MFM hard disk support is enabled.
114 X86-32 X86-32, aka i386 architecture is enabled.
115 X86-64 X86-64 architecture is enabled.
116 More X86-64 boot options can be found in
117 Documentation/x86/x86_64/boot-options.txt .
118 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
119 XEN Xen support is enabled
121 In addition, the following text indicates that the option:
123 BUGS= Relates to possible processor bugs on the said processor.
124 KNL Is a kernel start-up parameter.
125 BOOT Is a boot loader parameter.
127 Parameters denoted with BOOT are actually interpreted by the boot
128 loader, and have no meaning to the kernel directly.
129 Do not modify the syntax of boot loader parameters without extreme
130 need or coordination with <Documentation/x86/boot.txt>.
132 There are also arch-specific kernel-parameters not documented here.
133 See for example <Documentation/x86/x86_64/boot-options.txt>.
135 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
136 a trailing = on the name of any parameter states that that parameter will
137 be entered as an environment variable, whereas its absence indicates that
138 it will appear as a kernel argument readable via /proc/cmdline by programs
139 running once the system is up.
141 The number of kernel parameters is not limited, but the length of the
142 complete command line (parameters including spaces etc.) is limited to
143 a fixed number of characters. This limit depends on the architecture
144 and is between 256 and 4096 characters. It is defined in the file
145 ./include/asm/setup.h as COMMAND_LINE_SIZE.
149 Advanced Configuration and Power Interface
150 Format: { force | off | strict | noirq | rsdt }
151 force -- enable ACPI if default was off
152 off -- disable ACPI if default was on
153 noirq -- do not use ACPI for IRQ routing
154 strict -- Be less tolerant of platforms that are not
155 strictly ACPI specification compliant.
156 rsdt -- prefer RSDT over (default) XSDT
157 copy_dsdt -- copy DSDT to memory
159 See also Documentation/power/pm.txt, pci=noacpi
161 acpi_apic_instance= [ACPI, IOAPIC]
163 2: use 2nd APIC table, if available
164 1,0: use 1st APIC table
167 acpi_backlight= [HW,ACPI]
168 acpi_backlight=vendor
170 If set to vendor, prefer vendor specific driver
171 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
172 of the ACPI video.ko driver.
174 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
175 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
177 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
178 debug output. Bits in debug_layer correspond to a
179 _COMPONENT in an ACPI source file, e.g.,
180 #define _COMPONENT ACPI_PCI_COMPONENT
181 Bits in debug_level correspond to a level in
182 ACPI_DEBUG_PRINT statements, e.g.,
183 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
184 The debug_level mask defaults to "info". See
185 Documentation/acpi/debug.txt for more information about
186 debug layers and levels.
188 Enable processor driver info messages:
189 acpi.debug_layer=0x20000000
190 Enable PCI/PCI interrupt routing info messages:
191 acpi.debug_layer=0x400000
192 Enable AML "Debug" output, i.e., stores to the Debug
193 object while interpreting AML:
194 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
195 Enable all messages related to ACPI hardware:
196 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
198 Some values produce so much output that the system is
199 unusable. The "log_buf_len" parameter may be useful
200 if you need to capture more output.
202 acpi_display_output= [HW,ACPI]
203 acpi_display_output=vendor
204 acpi_display_output=video
207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
220 Format: <irq>,<irq>...
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
240 acpi_serialize [HW,ACPI] force serialization of AML methods
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
248 old_ordering, s4_nonvs, sci_force_enable }
249 See Documentation/power/video.txt for information on
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
259 nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during suspend/hibernation and resume.
261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
286 Format: <io>,<irq>,<dma>,<dma2>,<type>
288 add_efi_memmap [EFI; X86] Include EFI memory map in
289 kernel's map of available physical RAM.
292 See header of drivers/scsi/advansys.c.
294 aedsp16= [HW,OSS] Audio Excel DSP 16
295 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
296 See also header of sound/oss/aedsp16.c.
299 { off | try_unsupported }
300 off: disable AGP support
301 try_unsupported: try to drive unsupported chipsets
302 (may crash computer or cause data corruption)
305 See Documentation/scsi/aha152x.txt.
308 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
311 See Documentation/scsi/aic7xxx.txt.
314 See Documentation/scsi/aic79xx.txt.
317 Allow the default userspace alignment fault handler
318 behaviour to be specified. Bit 0 enables warnings,
319 bit 1 enables fixups, and bit 2 sends a segfault.
321 amd_iommu= [HW,X86-84]
322 Pass parameters to the AMD IOMMU driver in the system.
324 fullflush - enable flushing of IO/TLB entries when
325 they are unmapped. Otherwise they are
326 flushed before they will be reused, which
328 off - do not initialize any AMD IOMMU found in
331 amijoy.map= [HW,JOY] Amiga joystick support
332 Map of devices attached to JOY0DAT and JOY1DAT
334 See also Documentation/kernel/input/joystick.txt
336 analog.map= [HW,JOY] Analog joystick and gamepad support
337 Specifies type or capabilities of an analog joystick
338 connected to one of 16 gameports
339 Format: <type1>,<type2>,..<type16>
342 Power management functions (SPARCstation-4/5 + deriv.)
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
346 APC and your system crashes randomly.
348 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
349 Change the output verbosity whilst booting
350 Format: { quiet (default) | verbose | debug }
351 Change the amount of debugging information output
352 when initialising the APIC and IO-APIC components.
355 See Documentation/networking/ipv6.txt.
357 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
358 Limit apic dumping. The parameter defines the maximal
359 number of local apics being dumped. Also it is possible
360 to set it to "all" by meaning -- no limit here.
361 Format: { 1 (default) | 2 | ... | all }.
362 The parameter valid if only apic=debug or
363 apic=verbose is specified.
364 Example: apic=debug show_lapic=all
366 apm= [APM] Advanced Power Management
367 See header of arch/x86/kernel/apm_32.c.
369 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
370 Format: <io>,<irq>,<nodeID>
374 atarimouse= [HW,MOUSE] Atari Mouse
376 atascsi= [HW,SCSI] Atari SCSI
378 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
379 EzKey and similar keyboards
381 atkbd.reset= [HW] Reset keyboard during initialization
383 atkbd.set= [HW] Select keyboard code set
384 Format: <int> (2 = AT (default), 3 = PS/2)
386 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 atkbd.softraw= [HW] Choose between synthetic and real raw mode
390 Format: <bool> (0 = real, 1 = synthetic (default))
392 atkbd.softrepeat= [HW]
393 Use software keyboard repeat
397 baycom_epp= [HW,AX25]
400 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
402 See header of drivers/net/hamradio/baycom_par.c.
404 baycom_ser_fdx= [HW,AX25]
405 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
406 Format: <io>,<irq>,<mode>[,<baud>]
407 See header of drivers/net/hamradio/baycom_ser_fdx.c.
409 baycom_ser_hdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
411 Format: <io>,<irq>,<mode>
412 See header of drivers/net/hamradio/baycom_ser_hdx.c.
414 boot_delay= Milliseconds to delay each printk during boot.
415 Values larger than 10 seconds (10000) are changed to
419 bootmem_debug [KNL] Enable bootmem allocator debug messages.
421 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
422 bttv.radio= Most important insmod options are available as
424 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
425 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
428 See drivers/scsi/BusLogic.c, comment before function
429 BusLogic_ParseDriverOptions().
431 c101= [NET] Moxa C101 synchronous serial card
433 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
434 Sometimes CPU hardware bugs make them report the cache
435 size incorrectly. The kernel will attempt work arounds
436 to fix known problems, but for some CPUs it is not
437 possible to determine what the correct size should be.
438 This option provides an override for these situations.
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
460 Value can be changed at runtime via
461 /selinux/checkreqprot.
464 See Documentation/s390/CommonIO for details.
466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
468 Forces specified clocksource (if available) to be used
469 when calculating gettimeofday(). If specified
470 clocksource is not available, it defaults to PIT.
471 Format: { pit | tsc | cyclone | pmtmr }
473 clocksource= [GENERIC_TIME] Override the default clocksource
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
479 [all] jiffies (this is the base, fallback clocksource)
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
484 [X86-32] pit,hpet,tsc,vmi-timer;
485 scx200_hrt on Geode; cyclone on IBM x440
493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
495 arch/x86/include/asm/cpufeature.h for the valid bit
496 numbers. Note the Linux specific bits are not necessarily
497 stable over kernel options, but the vendor specific
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
506 cmo_free_hint= [PPC] Format: { yes | no }
507 Specify whether pages are marked as being inactive
508 when they are freed. This is used in CMO environments
509 to determine OS memory pressure for page stealing by
513 code_bytes [X86] How many bytes of object code to print
518 com20020= [HW,NET] ARCnet - COM20020 chipset
520 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
522 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
526 ARCnet - COM90xx chipset (memory-mapped buffers)
527 Format: <io>[,<irq>[,<memstart>]]
529 condev= [HW,S390] console device
532 console= [KNL] Output console device and options.
534 tty<n> Use the virtual console device <n>.
538 Use the specified serial port. The options are of
539 the form "bbbbpnf", where "bbbb" is the baud rate,
540 "p" is parity ("n", "o", or "e"), "n" is number of
541 bits, and "f" is flow control ("r" for RTS or
542 omit it). Default is "9600n8".
544 See Documentation/serial-console.txt for more
546 Documentation/networking/netconsole.txt for an
549 uart[8250],io,<addr>[,options]
550 uart[8250],mmio,<addr>[,options]
551 Start an early, polled-mode console on the 8250/16550
552 UART at the specified I/O port or MMIO address,
553 switching to the matching ttyS device later. The
554 options are the same as for ttyS, above.
556 If the device connected to the port is not a TTY but a braille
557 device, prepend "brl," before the device type, for instance
559 For now, only VisioBraille is supported.
561 consoleblank= [KNL] The console blank (screen saver) timeout in
562 seconds. Defaults to 10*60 = 10mins. A value of 0
563 disables the blank timer.
566 [KNL] Change the default value for
567 /proc/<pid>/coredump_filter.
568 See also Documentation/filesystems/proc.txt.
570 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
572 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
574 crashkernel=nn[KMG]@ss[KMG]
575 [KNL] Reserve a chunk of physical memory to
576 hold a kernel to switch to with kexec on panic.
578 crashkernel=range1:size1[,range2:size2,...][@offset]
579 [KNL] Same as above, but depends on the memory
580 in the running system. The syntax of range is
581 start-[end] where start and end are both
582 a memory unit (amount[KMG]). See also
583 Documentation/kdump/kdump.txt for a example.
588 cs89x0_media= [HW,NET]
589 Format: { rj45 | aui | bnc }
592 See header of drivers/s390/block/dasd_devmap.c.
594 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
595 (one device per port)
596 Format: <port#>,<type>
597 See also Documentation/input/joystick-parport.txt
599 debug [KNL] Enable kernel debugging (events log level).
602 [KNL] verbose self-tests
604 Print debugging info while doing the locking API
606 We default to 0 (no extra messages), setting it to
607 1 will print _a lot_ more information - normally
608 only useful to kernel developers.
610 debug_objects [KNL] Enable object debugging
613 [KNL] Disable object debugging
615 debugpat [X86] Enable PAT debugging
617 decnet.addr= [HW,NET]
618 Format: <area>[,<node>]
619 See also Documentation/networking/decnet.txt.
622 [same as hugepagesz=] The size of the default
623 HugeTLB page size. This is the size represented by
624 the legacy /proc/ hugepages APIs, used for SHM, and
625 default size when mounting hugetlbfs filesystems.
626 Defaults to the default architecture's huge page size
630 Set number of hash buckets for dentry cache.
633 IO parameters + enable/disable command.
635 digiepca= [HW,SERIAL]
636 See drivers/char/README.epca and
637 Documentation/serial/digiepca.txt.
640 See Documentation/networking/ipv6.txt.
643 See Documentation/networking/ipv6.txt.
645 disable_mtrr_cleanup [X86]
646 The kernel tries to adjust MTRR layout from continuous
647 to discrete, to make X server driver able to add WB
648 entry later. This parameter disables that.
650 disable_mtrr_trim [X86, Intel and AMD only]
651 By default the kernel will trim any uncacheable
652 memory out of your available memory pool based on
653 MTRR settings. This parameter disables that behavior,
654 possibly causing your machine to run very slowly.
656 disable_timer_pin_1 [X86]
657 Disable PIN 1 of APIC timer
658 Can be useful to work around chipset bugs.
660 dmasound= [HW,OSS] Sound subsystem buffers
662 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
663 this option disables the debugging code at boot.
665 dma_debug_entries=<number>
666 This option allows to tune the number of preallocated
667 entries for DMA-API debugging code. One entry is
668 required per DMA-API allocation. Use this if the
669 DMA-API debugging code disables itself because the
670 architectural default is too low.
672 dma_debug_driver=<driver_name>
673 With this option the DMA-API debugging driver
674 filter feature can be enabled at boot time. Just
675 pass the driver to filter for as the parameter.
676 The filter can be disabled or changed to another
677 driver later using sysfs.
683 dynamic_printk Enables pr_debug()/dev_dbg() calls if
684 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
685 These can also be switched on/off via
686 <debugfs>/dynamic_printk/modules
688 earlycon= [KNL] Output early console device and options.
689 uart[8250],io,<addr>[,options]
690 uart[8250],mmio,<addr>[,options]
691 Start an early, polled-mode console on the 8250/16550
692 UART at the specified I/O port or MMIO address.
693 The options are the same as for ttyS, above.
695 earlyprintk= [X86,SH,BLACKFIN]
697 earlyprintk=serial[,ttySn[,baudrate]]
698 earlyprintk=ttySn[,baudrate]
699 earlyprintk=dbgp[debugController#]
701 Append ",keep" to not disable it when the real console
704 Only vga or serial or usb debug port at a time.
706 Currently only ttyS0 and ttyS1 are supported.
708 Interaction with the standard serial driver is not
711 The VGA output is eventually overwritten by the real
714 ekgdboc= [X86,KGDB] Allow early kernel console debugging
717 This is desgined to be used in conjunction with
718 the boot argument: earlyprintk=vga
723 Format: {"off" | "on" | "skip[mbr]"}
725 eisa_irq_edge= [PARISC,HW]
726 See header of drivers/parisc/eisa.c.
729 See comment before function elanfreq_setup() in
730 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
733 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
734 See Documentation/block/as-iosched.txt and
735 Documentation/block/deadline-iosched.txt for details.
737 elfcorehdr= [IA64,PPC,SH,X86]
738 Specifies physical address of start of kernel core
739 image elf header. Generally kexec loader will
740 pass this option to capture kernel.
741 See Documentation/kdump/kdump.txt for details.
743 enable_mtrr_cleanup [X86]
744 The kernel tries to adjust MTRR layout from continuous
745 to discrete, to make X server driver able to add WB
746 entry later. This parameter enables that.
748 enable_timer_pin_1 [X86]
749 Enable PIN 1 of APIC timer
750 Can be useful to work around chipset bugs
751 (in particular on some ATI chipsets).
752 The kernel tries to set a reasonable default.
754 enforcing [SELINUX] Set initial enforcing status.
756 See security/selinux/Kconfig help text.
757 0 -- permissive (log only, no denials).
758 1 -- enforcing (deny and log).
760 Value can be changed at runtime via /selinux/enforce.
763 Disable Error Record Serialization Table (ERST)
766 ether= [HW,NET] Ethernet cards parameters
767 This option is obsoleted by the "netdev=" option, which
768 has equivalent usage. See its documentation for details.
772 fail_make_request=[KNL]
773 General fault injection mechanism.
774 Format: <interval>,<probability>,<space>,<times>
775 See also /Documentation/fault-injection/.
778 See header of drivers/scsi/fd_mcs.c.
781 See header of drivers/scsi/fdomain.c.
784 See Documentation/blockdev/floppy.txt.
786 force_pal_cache_flush
787 [IA-64] Avoid check_sal_cache_flush which may hang on
788 buggy SAL_CACHE_FLUSH implementations. Using this
789 parameter will force ia64_sal_cache_flush to call
790 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
793 [FTRACE] will set and start the specified tracer
794 as early as possible in order to facilitate early
797 ftrace_dump_on_oops[=orig_cpu]
798 [FTRACE] will dump the trace buffers on oops.
799 If no parameter is passed, ftrace will dump
800 buffers of all CPUs, but if you pass orig_cpu, it will
801 dump only the buffer of the CPU that triggered the
804 ftrace_filter=[function-list]
805 [FTRACE] Limit the functions traced by the function
806 tracer at boot up. function-list is a comma separated
807 list of functions. This list can be changed at run
808 time by the set_ftrace_filter file in the debugfs
811 ftrace_notrace=[function-list]
812 [FTRACE] Do not trace the functions specified in
813 function-list. This list can be changed at run time
814 by the set_ftrace_notrace file in the debugfs
817 ftrace_graph_filter=[function-list]
818 [FTRACE] Limit the top level callers functions traced
819 by the function graph tracer at boot up.
820 function-list is a comma separated list of functions
821 that can be changed at run time by the
822 set_graph_function file in the debugfs tracing directory.
825 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
826 support via parallel port (up to 5 devices per port)
827 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
828 See also Documentation/input/joystick-parport.txt
832 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
836 gcov_persist= [GCOV] When non-zero (default), profiling data for
837 kernel modules is saved and remains accessible via
838 debugfs, even when the module is unloaded/reloaded.
839 When zero, profiling data is discarded and associated
840 debugfs files are removed at module unload time.
843 See header of drivers/scsi/gdth.c.
845 gpt [EFI] Forces disk with valid GPT signature but
846 invalid Protective MBR to be treated as GPT.
850 hashdist= [KNL,NUMA] Large hashes allocated during boot
851 are distributed across NUMA nodes. Defaults on
852 for 64bit NUMA, off otherwise.
853 Format: 0 | 1 (for off | on)
855 hcl= [IA-64] SGI's Hardware Graph compatibility layer
857 hd= [EIDE] (E)IDE hard drive subsystem geometry
858 Format: <cyl>,<head>,<sect>
861 Disable Hardware Error Source Table (HEST) support;
862 corresponding firmware-first mode error processing
863 logic will be disabled.
865 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
866 size of <nn>. This works even on boxes that have no
867 highmem otherwise. This also works to reduce highmem
868 size on bigger boxes.
870 highres= [KNL] Enable/disable high resolution timer mode.
871 Valid parameters: "on", "off"
875 See Documentation/isdn/README.HiSax.
879 hpet= [X86-32,HPET] option to control HPET usage
880 Format: { enable (default) | disable | force |
882 disable: disable HPET and use PIT instead
883 force: allow force enabled of undocumented chips (ICH4,
885 verbose: show contents of HPET registers during setup
887 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
888 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
889 On x86-64 and powerpc, this option can be specified
890 multiple times interleaved with hugepages= to reserve
891 huge pages of different sizes. Valid pages sizes on
892 x86-64 are 2M (when the CPU supports "pse") and 1G
893 (when the CPU supports the "pdpe1gb" cpuinfo flag)
894 Note that 1GB pages can only be allocated at boot time
895 using hugepages= and not freed afterwards.
897 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
898 terminal devices. Valid values: 0..8
899 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
900 If specified, z/VM IUCV HVC accepts connections
901 from listed z/VM user IDs only.
903 i2c_bus= [HW] Override the default board specific I2C bus speed
904 or register an additional I2C bus that is not
905 registered from board initialization code.
909 i8042.debug [HW] Toggle i8042 debug mode
910 i8042.direct [HW] Put keyboard port into non-translated mode
911 i8042.dumbkbd [HW] Pretend that controller can only read data from
912 keyboard and cannot control its state
913 (Don't attempt to blink the leds)
914 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
915 i8042.nokbd [HW] Don't check/create keyboard port
916 i8042.noloop [HW] Disable the AUX Loopback command while probing
918 i8042.nomux [HW] Don't check presence of an active multiplexing
920 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
923 [HW] Frequency with which keyboard LEDs should blink
924 when kernel panics (default is 0.5 sec)
925 i8042.reset [HW] Reset the controller during init and cleanup
926 i8042.unlock [HW] Unlock (ignore) the keylock
930 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
931 indicates that the driver is running on unsupported
933 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
934 does not match list of supported models.
936 [HW] Report power status in /proc/i8k
937 (disabled by default)
938 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
941 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
942 See Documentation/mca.txt.
945 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
947 ide-core.nodma= [HW] (E)IDE subsystem
948 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
949 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
950 .cdrom .chs .ignore_cable are additional options
951 See Documentation/ide/ide.txt.
953 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
954 Claim all unknown PCI IDE storage controllers.
957 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
958 Poll forces a polling idle loop that can slightly
959 improve the performance of waking up a idle CPU, but
960 will use a lot of power and make the system run hot.
962 idle=mwait: On systems which support MONITOR/MWAIT but
963 the kernel chose to not use it because it doesn't save
964 as much power as a normal idle loop, use the
965 MONITOR/MWAIT idle loop anyways. Performance should be
966 the same as idle=poll.
967 idle=halt: Halt is forced to be used for CPU idle.
968 In such case C2/C3 won't be used again.
969 idle=nomwait: Disable mwait for CPU C-states
971 ignore_loglevel [KNL]
972 Ignore loglevel setting - this will print /all/
973 kernel messages to the console. Useful for debugging.
976 Set number of hash buckets for inode cache.
979 Format: { "0" | "1" }
980 0 -- integrity auditing messages. (Default)
981 1 -- enable informational integrity auditing messages.
984 Format: { "sha1" | "md5" }
988 Load a policy which meets the needs of the Trusted
989 Computing Base. This means IMA will measure all
990 programs exec'd, files mmap'd for exec, and all files
991 opened for read by uid=0.
994 See header of drivers/scsi/in2000.c.
998 Run specified binary instead of /sbin/init as init
1001 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1002 for working out where the kernel is dying during
1005 initrd= [BOOT] Specify the location of the initial ramdisk
1007 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1010 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1012 Enable intel iommu driver.
1014 Disable intel iommu driver.
1015 igfx_off [Default Off]
1016 By default, gfx is mapped as normal device. If a gfx
1017 device has a dedicated DMAR unit, the DMAR unit is
1018 bypassed by not enabling DMAR with this option. In
1019 this case, gfx device will use physical address for
1022 With this option iommu will not optimize to look
1023 for io virtual address below 32 bit forcing dual
1024 address cycle on pci bus for cards supporting greater
1025 than 32 bit addressing. The default is to look
1026 for translation below 32 bit and if not available
1027 then look in the higher range.
1028 strict [Default Off]
1029 With this option on every unmap_single operation will
1030 result in a hardware IOTLB flush operation as opposed
1031 to batching them for performance.
1035 iomem= Disable strict checking of access to MMIO memory
1036 strict regions from userspace.
1052 io7= [HW] IO7 for Marvel based alpha systems
1053 See comment before marvel_specify_io7 in
1054 arch/alpha/kernel/core_marvel.c.
1056 io_delay= [X86] I/O delay method
1058 Standard port 0x80 based delay
1060 Alternate port 0xed based delay (needed on some systems)
1062 Simple two microseconds delay
1067 See Documentation/filesystems/nfs/nfsroot.txt.
1069 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1070 See comment before ip2_setup() in
1071 drivers/char/ip2/ip2base.c.
1073 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1074 See header of drivers/scsi/ips.c.
1077 When an interrupt is not handled search all handlers
1078 for it. Intended to get systems with badly broken
1082 When an interrupt is not handled search all handlers
1083 for it. Also check all handlers each timer
1084 interrupt. Intended to get systems with badly broken
1088 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1090 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1092 <cpu number>,...,<cpu number>
1094 <cpu number>-<cpu number>
1095 (must be a positive range in ascending order)
1097 <cpu number>,...,<cpu number>-<cpu number>
1099 This option can be used to specify one or more CPUs
1100 to isolate from the general SMP balancing and scheduling
1101 algorithms. You can move a process onto or off an
1102 "isolated" CPU via the CPU affinity syscalls or cpuset.
1103 <cpu number> begins at 0 and the maximum value is
1104 "number of CPUs in system - 1".
1106 This option is the preferred way to isolate CPUs. The
1107 alternative -- manually setting the CPU mask of all
1108 tasks in the system -- can cause problems and
1109 suboptimal load balancer performance.
1113 js= [HW,JOY] Analog joystick
1114 See Documentation/input/joystick.txt.
1118 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1119 specifies the amount of memory usable by the kernel
1120 for non-movable allocations. The requested amount is
1121 spread evenly throughout all nodes in the system. The
1122 remaining memory in each node is used for Movable
1123 pages. In the event, a node is too small to have both
1124 kernelcore and Movable pages, kernelcore pages will
1125 take priority and other nodes will have a larger number
1126 of kernelcore pages. The Movable zone is used for the
1127 allocation of pages that may be reclaimed or moved
1128 by the page migration subsystem. This means that
1129 HugeTLB pages may not be allocated from this zone.
1130 Note that allocations like PTEs-from-HighMem still
1131 use the HighMem zone if it exists, and the Normal
1132 zone if it does not.
1134 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1135 Format: <Controller#>[,poll interval]
1136 The controller # is the number of the ehci usb debug
1137 port as it is probed via PCI. The poll interval is
1138 optional and is the number seconds in between
1139 each poll cycle to the debug port in case you need
1140 the functionality for interrupting the kernel with
1141 gdb or control-c on the dbgp connection. When
1142 not using this parameter you use sysrq-g to break into
1143 the kernel debugger.
1145 kgdboc= [KGDB,HW] kgdb over consoles.
1146 Requires a tty driver that supports console polling,
1147 or a supported polling keyboard driver (non-usb).
1148 Serial only format: <serial_device>[,baud]
1149 keyboard only format: kbd
1150 keyboard and serial format: kbd,<serial_device>[,baud]
1151 Optional Kernel mode setting:
1152 kms, kbd format: kms,kbd
1153 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1155 kgdbwait [KGDB] Stop kernel execution and enter the
1156 kernel debugger at the earliest opportunity.
1158 kmac= [MIPS] korina ethernet MAC address.
1159 Configure the RouterBoard 532 series on-chip
1160 Ethernet adapter MAC address.
1162 kmemleak= [KNL] Boot-time kmemleak enable/disable
1163 Valid arguments: on, off
1166 kstack=N [X86] Print N words from the kernel stack
1169 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1170 Default is 0 (don't ignore, but inject #GP)
1172 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1173 Default is 1 (enabled)
1175 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1178 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1180 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1182 kvm-intel.bypass_guest_pf=
1183 [KVM,Intel] Disables bypassing of guest page faults
1184 on Intel chips. Default is 1 (enabled)
1186 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1187 (virtualized MMU) support on capable Intel chips.
1188 Default is 1 (enabled)
1190 kvm-intel.emulate_invalid_guest_state=
1191 [KVM,Intel] Enable emulation of invalid guest states
1192 Default is 0 (disabled)
1194 kvm-intel.flexpriority=
1195 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1196 Default is 1 (enabled)
1198 kvm-intel.unrestricted_guest=
1199 [KVM,Intel] Disable unrestricted guest feature
1200 (virtualized real and unpaged mode) on capable
1201 Intel chips. Default is 1 (enabled)
1203 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1204 feature (tagged TLBs) on capable Intel chips.
1205 Default is 1 (enabled)
1211 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1214 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1217 libata.dma= [LIBATA] DMA control
1218 libata.dma=0 Disable all PATA and SATA DMA
1219 libata.dma=1 PATA and SATA Disk DMA only
1220 libata.dma=2 ATAPI (CDROM) DMA only
1221 libata.dma=4 Compact Flash DMA only
1222 Combinations also work, so libata.dma=3 enables DMA
1223 for disks and CDROMs, but not CFs.
1225 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1226 libata.ignore_hpa=0 keep BIOS limits (default)
1227 libata.ignore_hpa=1 ignore limits, using full disk
1229 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1233 libata.force= [LIBATA] Force configurations. The format is comma
1234 separated list of "[ID:]VAL" where ID is
1235 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1236 matching port, link or device. Basically, it matches
1237 the ATA ID string printed on console by libata. If
1238 the whole ID part is omitted, the last PORT and DEVICE
1239 values are used. If ID hasn't been specified yet, the
1240 configuration applies to all ports, links and devices.
1242 If only DEVICE is omitted, the parameter applies to
1243 the port and all links and devices behind it. DEVICE
1244 number of 0 either selects the first device or the
1245 first fan-out link behind PMP device. It does not
1246 select the host link. DEVICE number of 15 selects the
1247 host link and device attached to it.
1249 The VAL specifies the configuration to force. As long
1250 as there's no ambiguity shortcut notation is allowed.
1251 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1252 The following configurations can be forced.
1254 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1255 Any ID with matching PORT is used.
1257 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1259 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1260 udma[/][16,25,33,44,66,100,133] notation is also
1263 * [no]ncq: Turn on or off NCQ.
1265 * nohrst, nosrst, norst: suppress hard, soft
1268 * dump_id: dump IDENTIFY data.
1270 If there are multiple matching configurations changing
1271 the same attribute, the last one is used.
1273 memblock=debug [KNL] Enable memblock debug messages.
1275 load_ramdisk= [RAM] List of ramdisks to load from floppy
1276 See Documentation/blockdev/ramdisk.txt.
1278 lockd.nlm_grace_period=P [NFS] Assign grace period.
1281 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1284 lockd.nlm_timeout=T [NFS] Assign timeout value.
1287 lockd.nlm_udpport=M [NFS] Assign UDP port.
1290 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1293 loglevel= All Kernel Messages with a loglevel smaller than the
1294 console loglevel will be printed to the console. It can
1295 also be changed with klogd or other programs. The
1296 loglevels are defined as follows:
1298 0 (KERN_EMERG) system is unusable
1299 1 (KERN_ALERT) action must be taken immediately
1300 2 (KERN_CRIT) critical conditions
1301 3 (KERN_ERR) error conditions
1302 4 (KERN_WARNING) warning conditions
1303 5 (KERN_NOTICE) normal but significant condition
1304 6 (KERN_INFO) informational
1305 7 (KERN_DEBUG) debug-level messages
1307 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1308 Format: { n | nk | nM }
1309 n must be a power of two. The default size
1310 is set in the kernel config file.
1312 logo.nologo [FB] Disables display of the built-in Linux logo.
1313 This may be used to provide more screen space for
1314 kernel log messages and is useful when debugging
1315 kernel boot problems.
1317 lp=0 [LP] Specify parallel ports to use, e.g,
1318 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1319 lp=reset first parallel port). 'lp=0' disables the
1320 lp=auto printer driver. 'lp=reset' (which can be
1321 specified in addition to the ports) causes
1322 attached printers to be reset. Using
1323 lp=port1,port2,... specifies the parallel ports
1324 to associate lp devices with, starting with
1325 lp0. A port specification may be 'none' to skip
1326 that lp device, or a parport name such as
1327 'parport0'. Specifying 'lp=auto' instead of a
1328 port specification list means that device IDs
1329 from each port should be examined, to see if
1330 an IEEE 1284-compliant printer is attached; if
1331 so, the driver will manage that printer.
1332 See also header of drivers/char/lp.c.
1335 Sets loops_per_jiffy to given constant, thus avoiding
1336 time-consuming boot-time autodetection (up to 250 ms per
1337 CPU). 0 enables autodetection (default). To determine
1338 the correct value for your kernel, boot with normal
1339 autodetection and see what value is printed. Note that
1340 on SMP systems the preset will be applied to all CPUs,
1341 which is likely to cause problems if your CPUs need
1342 significantly divergent settings. An incorrect value
1343 will cause delays in the kernel to be wrong, leading to
1344 unpredictable I/O errors and other breakage. Although
1345 unlikely, in the extreme case this might damage your
1349 Format: <io>,<irq>,<dma>
1351 mac5380= [HW,SCSI] Format:
1352 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1354 machvec= [IA64] Force the use of a particular machine-vector
1355 (machvec) in a generic kernel.
1356 Example: machvec=hpzx1_swiotlb
1358 machtype= [Loongson] Share the same kernel image file between different
1360 Example: machtype=lemote-yeeloong-2f-7inch
1362 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1363 than or equal to this physical address is ignored.
1365 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1366 should make use of. maxcpus=n : n >= 0 limits the
1367 kernel to using 'n' processors. n=0 is a special case,
1368 it is equivalent to "nosmp", which also disables
1371 max_loop= [LOOP] Maximum number of loopback devices that can
1375 max_luns= [SCSI] Maximum number of LUNs to probe.
1376 Should be between 1 and 2^32-1.
1379 [SCSI] Maximum number of LUNs received.
1380 Should be between 1 and 16384.
1384 mce [X86-32] Machine Check Exception
1386 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1388 md= [HW] RAID subsystems devices and level
1389 See Documentation/md.txt.
1392 Format: <first>,<last>
1393 Specifies range of consoles to be captured by the MDA.
1395 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1396 Amount of memory to be used when the kernel is not able
1397 to see the whole system memory or for test.
1398 [X86-32] Use together with memmap= to avoid physical
1399 address space collisions. Without memmap= PCI devices
1400 could be placed at addresses belonging to unused RAM.
1402 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1406 [KNL,SH] Allow user to override the default size for
1407 per-device physically contiguous DMA buffers.
1409 memmap=exactmap [KNL,X86] Enable setting of an exact
1410 E820 memory map, as specified by the user.
1411 Such memmap=exactmap lines can be constructed based on
1412 BIOS output or other requirements. See the memmap=nn@ss
1415 memmap=nn[KMG]@ss[KMG]
1416 [KNL] Force usage of a specific region of memory
1417 Region of memory to be used, from ss to ss+nn.
1419 memmap=nn[KMG]#ss[KMG]
1420 [KNL,ACPI] Mark specific memory as ACPI data.
1421 Region of memory to be used, from ss to ss+nn.
1423 memmap=nn[KMG]$ss[KMG]
1424 [KNL,ACPI] Mark specific memory as reserved.
1425 Region of memory to be used, from ss to ss+nn.
1426 Example: Exclude memory from 0x18690000-0x1869ffff
1427 memmap=64K$0x18690000
1429 memmap=0x10000$0x18690000
1431 memory_corruption_check=0/1 [X86]
1432 Some BIOSes seem to corrupt the first 64k of
1433 memory when doing things like suspend/resume.
1434 Setting this option will scan the memory
1435 looking for corruption. Enabling this will
1436 both detect corruption and prevent the kernel
1437 from using the memory being corrupted.
1438 However, its intended as a diagnostic tool; if
1439 repeatable BIOS-originated corruption always
1440 affects the same memory, you can use memmap=
1441 to prevent the kernel from using that memory.
1443 memory_corruption_check_size=size [X86]
1444 By default it checks for corruption in the low
1445 64k, making this memory unavailable for normal
1446 use. Use this parameter to scan for
1447 corruption in more or less memory.
1449 memory_corruption_check_period=seconds [X86]
1450 By default it checks for corruption every 60
1451 seconds. Use this parameter to check at some
1452 other rate. 0 disables periodic checking.
1454 memtest= [KNL,X86] Enable memtest
1456 default : 0 <disable>
1457 Specifies the number of memtest passes to be
1458 performed. Each pass selects another test
1459 pattern from a given set of patterns. Memtest
1460 fills the memory with this pattern, validates
1461 memory contents and reserves bad memory
1462 regions that are detected.
1464 meye.*= [HW] Set MotionEye Camera parameters
1465 See Documentation/video4linux/meye.txt.
1467 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1468 Multi-Function General Purpose Timers on AMD Geode
1471 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1472 the BIOS has incorrectly applied a workaround. TinyBIOS
1473 version 0.98 is known to be affected, 0.99 fixes the
1474 problem by letting the user disable the workaround.
1478 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1479 physical address is ignored.
1481 mini2440= [ARM,HW,KNL]
1482 Format:[0..2][b][c][t]
1484 MINI2440 configuration specification:
1485 0 - The attached screen is the 3.5" TFT
1486 1 - The attached screen is the 7" TFT
1487 2 - The VGA Shield is attached (1024x768)
1488 Leaving out the screen size parameter will not load
1489 the TFT driver, and the framebuffer will be left
1491 b - Enable backlight. The TFT backlight pin will be
1492 linked to the kernel VESA blanking code and a GPIO
1493 LED. This parameter is not necessary when using the
1495 c - Enable the s3c camera interface.
1496 t - Reserved for enabling touchscreen support. The
1497 touchscreen support is not enabled in the mainstream
1498 kernel as of 2.6.30, a preliminary port can be found
1499 in the "bleeding edge" mini2440 support kernel at
1500 http://repo.or.cz/w/linux-2.6/mini2440.git
1503 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1504 parameter allows control of the logging verbosity for
1505 the additional memory initialisation checks. A value
1506 of 0 disables mminit logging and a level of 4 will
1507 log everything. Information is printed at KERN_DEBUG
1508 so loglevel=8 may also need to be specified.
1511 [MOUSE] Maximum time between finger touching and
1512 leaving touchpad surface for touch to be considered
1513 a tap and be reported as a left button click (for
1514 touchpads working in absolute mode only).
1516 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1517 reporting absolute coordinates, such as tablets
1518 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1519 reporting absolute coordinates, such as tablets
1521 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1522 is similar to kernelcore except it specifies the
1523 amount of memory used for migratable allocations.
1524 If both kernelcore and movablecore is specified,
1525 then kernelcore will be at *least* the specified
1526 value but may be more. If movablecore on its own
1527 is specified, the administrator must be careful
1528 that the amount of memory usable for all allocations
1534 MTD_Partition= [MTD]
1535 Format: <name>,<region-number>,<size>,<offset>
1537 MTD_Region= [MTD] Format:
1538 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1541 See drivers/mtd/cmdlinepart.c.
1543 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1545 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1547 boundary - index of last SLC block on Flex-OneNAND.
1548 The remaining blocks are configured as MLC blocks.
1549 lock - Configure if Flex-OneNAND boundary should be locked.
1550 Once locked, the boundary cannot be changed.
1551 1 indicates lock status, 0 indicates unlock status.
1554 ARM/S3C2412 JIVE boot control
1556 See arch/arm/mach-s3c2412/mach-jive.c
1558 mtouchusb.raw_coordinates=
1559 [HW] Make the MicroTouch USB driver use raw coordinates
1560 ('y', default) or cooked coordinates ('n')
1562 mtrr_chunk_size=nn[KMG] [X86]
1563 used for mtrr cleanup. It is largest continuous chunk
1564 that could hold holes aka. UC entries.
1566 mtrr_gran_size=nn[KMG] [X86]
1567 Used for mtrr cleanup. It is granularity of mtrr block.
1569 Large value could prevent small alignment from
1572 mtrr_spare_reg_nr=n [X86]
1574 Range: 0,7 : spare reg number
1576 Used for mtrr cleanup. It is spare mtrr entries number.
1577 Set to 2 or more if your graphical card needs more.
1579 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1582 See header of drivers/scsi/NCR_D700.c.
1586 ncr53c400= [HW,SCSI]
1588 ncr53c400a= [HW,SCSI]
1590 ncr53c406a= [HW,SCSI]
1592 ncr53c8xx= [HW,SCSI]
1594 netdev= [NET] Network devices parameters
1595 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1596 Note that mem_start is often overloaded to mean
1597 something different and driver-specific.
1598 This usage is only documented in each driver source
1602 [NETFILTER] Enable connection tracking flow accounting
1603 0 to disable accounting
1604 1 to enable accounting
1608 See Documentation/filesystems/nfs/nfsroot.txt.
1610 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1611 See Documentation/filesystems/nfs/nfsroot.txt.
1613 nfs.callback_tcpport=
1614 [NFS] set the TCP port on which the NFSv4 callback
1615 channel should listen.
1618 [NFS] sets the pathname to the program which is used
1619 to update the NFS client cache entries.
1621 nfs.cache_getent_timeout=
1622 [NFS] sets the timeout after which an attempt to
1623 update a cache entry is deemed to have failed.
1625 nfs.idmap_cache_timeout=
1626 [NFS] set the maximum lifetime for idmapper cache
1630 [NFS] enable 64-bit inode numbers.
1631 If zero, the NFS client will fake up a 32-bit inode
1632 number for the readdir() and stat() syscalls instead
1633 of returning the full 64-bit number.
1634 The default is to return 64-bit inode numbers.
1636 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1637 when a NMI is triggered.
1638 Format: [state][,regs][,debounce][,die]
1640 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1641 Format: [panic,][num]
1643 0 - turn nmi_watchdog off
1644 1 - use the IO-APIC timer for the NMI watchdog
1645 2 - use the local APIC for the NMI watchdog using
1646 a performance counter. Note: This will use one
1647 performance counter and the local APIC's performance
1649 When panic is specified, panic when an NMI watchdog
1651 This is useful when you use a panic=... timeout and
1652 need the box quickly up again.
1653 Instead of 1 and 2 it is possible to use the following
1654 symbolic names: lapic and ioapic
1655 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1657 netpoll.carrier_timeout=
1658 [NET] Specifies amount of time (in seconds) that
1659 netpoll should wait for a carrier. By default netpoll
1662 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1663 emulation library even if a 387 maths coprocessor
1667 [HW] Never suspend the console
1668 Disable suspending of consoles during suspend and
1669 hibernate operations. Once disabled, debugging
1670 messages can reach various consoles while the rest
1671 of the system is being put to sleep (ie, while
1672 debugging driver suspend/resume hooks). This may
1673 not work reliably with all consoles, but is known
1674 to work with serial and VGA consoles.
1676 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1677 caches in the slab allocator. Saves per-node memory,
1678 but will impact performance.
1682 noapic [SMP,APIC] Tells the kernel to not make use of any
1683 IOAPICs that may be present in the system.
1685 nobats [PPC] Do not use BATs for mapping kernel lowmem
1686 on "Classic" PPC cores.
1690 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1692 nodelayacct [KNL] Disable per-task delay accounting
1694 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1696 nodsp [SH] Disable hardware DSP at boot time.
1698 noefi [X86] Disable EFI runtime services support.
1703 On X86-32 available only on PAE configured kernels.
1704 noexec=on: enable non-executable mappings (default)
1705 noexec=off: disable non-executable mappings
1708 This affects only 32-bit executables.
1709 noexec32=on: enable non-executable mappings (default)
1710 read doesn't imply executable mappings
1711 noexec32=off: disable non-executable mappings
1712 read implies executable mappings
1714 nofpu [SH] Disable hardware FPU at boot time.
1716 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1717 register save and restore. The kernel will only save
1718 legacy floating-point registers on task switch.
1720 noxsave [BUGS=X86] Disables x86 extended register state save
1721 and restore using xsave. The kernel will fallback to
1722 enabling legacy floating-point and sse state.
1724 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1725 wfi(ARM) instruction doesn't work correctly and not to
1726 use it. This is also useful when using JTAG debugger.
1728 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1729 instruction doesn't work correctly and not to
1732 no_file_caps Tells the kernel not to honor file capabilities. The
1733 only way then for a file to be executed with privilege
1734 is to be setuid root or executed by root.
1736 nohalt [IA-64] Tells the kernel not to use the power saving
1737 function PAL_HALT_LIGHT when idle. This increases
1738 power-consumption. On the positive side, it reduces
1739 interrupt wake-up latency, which may improve performance
1740 in certain environments such as networked servers or
1743 nohz= [KNL] Boottime enable/disable dynamic ticks
1744 Valid arguments: on, off
1747 noiotrap [SH] Disables trapped I/O port accesses.
1749 noirqdebug [X86-32] Disables the code which attempts to detect and
1750 disable unhandled interrupt sources.
1752 no_timer_check [X86,APIC] Disables the code which tests for
1753 broken timer IRQ sources.
1755 noisapnp [ISAPNP] Disables ISA PnP code.
1757 noinitrd [RAM] Tells the kernel not to load any configured
1760 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1765 nojitter [IA64] Disables jitter checking for ITC timers.
1767 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1769 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1771 noltlbs [PPC] Do not use large page/tlb entries for kernel
1772 lowmem mapping on PPC40x.
1774 nomca [IA-64] Disable machine check abort handling
1776 nomce [X86-32] Machine Check Exception
1778 nomfgpt [X86-32] Disable Multi-Function General Purpose
1779 Timer usage (for AMD Geode machines).
1781 nopat [X86] Disable PAT (page attribute table extension of
1782 pagetables) support.
1784 norandmaps Don't use address space randomization. Equivalent to
1785 echo 0 > /proc/sys/kernel/randomize_va_space
1787 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1789 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1790 with UP alternatives
1792 noresidual [PPC] Don't use residual data on PReP machines.
1794 noresume [SWSUSP] Disables resume and restores original swap
1797 no-scroll [VGA] Disables scrollback.
1798 This is required for the Braillex ib80-piezo Braille
1799 reader made by F.H. Papenmeier (Germany).
1803 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1805 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1806 and disable the IO APIC. legacy for "maxcpus=0".
1808 nosoftlockup [KNL] Disable the soft-lockup detector.
1810 noswapaccount [KNL] Disable accounting of swap in memory resource
1811 controller. (See Documentation/cgroups/memory.txt)
1813 nosync [HW,M68K] Disables sync negotiation for all devices.
1815 notsc [BUGS=X86-32] Disable Time Stamp Counter
1817 nousb [USB] Disable the USB subsystem
1819 nowatchdog [KNL] Disable the lockup detector.
1823 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1825 nptcg= [IA64] Override max number of concurrent global TLB
1826 purges which is reported from either PAL_VM_SUMMARY or
1829 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1830 could support. nr_cpus=n : n >= 1 limits the kernel to
1831 supporting 'n' processors. Later in runtime you can not
1832 use hotplug cpu feature to put more cpu back to online.
1833 just like you compile the kernel NR_CPUS=n
1835 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1837 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1838 one of ['zone', 'node', 'default'] can be specified
1839 This can be set from sysctl after boot.
1840 See Documentation/sysctl/vm.txt for details.
1842 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1843 See Documentation/debugging-via-ohci1394.txt for more
1846 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1847 Rather than timing out after 20 ms if an EC
1848 command is not properly ACKed, override the length
1849 of the timeout. We have interrupts disabled while
1850 waiting for the ACK, so if this is set too high
1851 interrupts *may* be lost!
1853 omap_mux= [OMAP] Override bootloader pin multiplexing.
1854 Format: <mux_mode0.mode_name=value>...
1855 For example, to override I2C bus2:
1856 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1861 oprofile.timer= [HW]
1862 Use timer interrupt instead of performance counters
1864 oprofile.cpu_type= Force an oprofile cpu type
1865 This might be useful if you have an older oprofile
1866 userland or if you want common events.
1867 Format: { arch_perfmon }
1868 arch_perfmon: [X86] Force use of architectural
1869 perfmon on Intel CPUs instead of the
1870 CPU specific event set.
1872 osst= [HW,SCSI] SCSI Tape Driver
1873 Format: <buffer_size>,<write_threshold>
1874 See also Documentation/scsi/st.txt.
1876 panic= [KNL] Kernel behaviour on panic
1879 parkbd.port= [HW] Parallel port number the keyboard adapter is
1880 connected to, default is 0.
1882 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1883 0 for XT, 1 for AT (default is AT).
1886 parport= [HW,PPT] Specify parallel ports. 0 disables.
1887 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1888 Use 'auto' to force the driver to use any
1889 IRQ/DMA settings detected (the default is to
1890 ignore detected IRQ/DMA settings because of
1891 possible conflicts). You can specify the base
1892 address, IRQ, and DMA settings; IRQ and DMA
1893 should be numbers, or 'auto' (for using detected
1894 settings on that particular port), or 'nofifo'
1895 (to avoid using a FIFO even if it is detected).
1896 Parallel ports are assigned in the order they
1897 are specified on the command line, starting
1900 parport_init_mode= [HW,PPT]
1901 Configure VIA parallel port to operate in
1902 a specific mode. This is necessary on Pegasos
1903 computer where firmware has no options for setting
1904 up parallel port mode and sets it to spp.
1905 Currently this function knows 686a and 8231 chips.
1906 Format: [spp|ps2|epp|ecp|ecpepp]
1908 pas2= [HW,OSS] Format:
1909 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1912 See header of drivers/scsi/pas16.c.
1915 Halt all CPUs after the first oops has been printed for
1916 the specified number of seconds. This is to be used if
1917 your oopses keep scrolling off the screen.
1922 See header of drivers/block/paride/pcd.c.
1923 See also Documentation/blockdev/paride.txt.
1925 pci=option[,option...] [PCI] various PCI subsystem options:
1926 earlydump [X86] dump PCI config space before the kernel
1928 off [X86] don't probe for the PCI bus
1929 bios [X86-32] force use of PCI BIOS, don't access
1930 the hardware directly. Use this if your machine
1931 has a non-standard PCI host bridge.
1932 nobios [X86-32] disallow use of PCI BIOS, only direct
1933 hardware access methods are allowed. Use this
1934 if you experience crashes upon bootup and you
1935 suspect they are caused by the BIOS.
1936 conf1 [X86] Force use of PCI Configuration
1938 conf2 [X86] Force use of PCI Configuration
1940 noaer [PCIE] If the PCIEAER kernel config parameter is
1941 enabled, this kernel boot option can be used to
1942 disable the use of PCIE advanced error reporting.
1943 nodomains [PCI] Disable support for multiple PCI
1944 root domains (aka PCI segments, in ACPI-speak).
1945 nommconf [X86] Disable use of MMCONFIG for PCI
1947 check_enable_amd_mmconf [X86] check for and enable
1948 properly configured MMIO access to PCI
1949 config space on AMD family 10h CPU
1950 nomsi [MSI] If the PCI_MSI kernel config parameter is
1951 enabled, this kernel boot option can be used to
1952 disable the use of MSI interrupts system-wide.
1953 noioapicquirk [APIC] Disable all boot interrupt quirks.
1954 Safety option to keep boot IRQs enabled. This
1955 should never be necessary.
1956 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1957 primary IO-APIC for bridges that cannot disable
1958 boot IRQs. This fixes a source of spurious IRQs
1959 when the system masks IRQs.
1960 noioapicreroute [APIC] Disable workaround that uses the
1961 boot IRQ equivalent of an IRQ that connects to
1962 a chipset where boot IRQs cannot be disabled.
1963 The opposite of ioapicreroute.
1964 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1965 routing table. These calls are known to be buggy
1966 on several machines and they hang the machine
1967 when used, but on other computers it's the only
1968 way to get the interrupt routing table. Try
1969 this option if the kernel is unable to allocate
1970 IRQs or discover secondary PCI buses on your
1972 rom [X86] Assign address space to expansion ROMs.
1973 Use with caution as certain devices share
1974 address decoders between ROMs and other
1976 norom [X86] Do not assign address space to
1977 expansion ROMs that do not already have
1978 BIOS assigned address ranges.
1979 nobar [X86] Do not assign address space to the
1980 BARs that weren't assigned by the BIOS.
1981 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1982 assigned automatically to PCI devices. You can
1983 make the kernel exclude IRQs of your ISA cards
1985 pirqaddr=0xAAAAA [X86] Specify the physical address
1986 of the PIRQ table (normally generated
1987 by the BIOS) if it is outside the
1988 F0000h-100000h range.
1989 lastbus=N [X86] Scan all buses thru bus #N. Can be
1990 useful if the kernel is unable to find your
1991 secondary buses and you want to tell it
1992 explicitly which ones they are.
1993 assign-busses [X86] Always assign all PCI bus
1994 numbers ourselves, overriding
1995 whatever the firmware may have done.
1996 usepirqmask [X86] Honor the possible IRQ mask stored
1997 in the BIOS $PIR table. This is needed on
1998 some systems with broken BIOSes, notably
1999 some HP Pavilion N5400 and Omnibook XE3
2000 notebooks. This will have no effect if ACPI
2001 IRQ routing is enabled.
2002 noacpi [X86] Do not use ACPI for IRQ routing
2003 or for PCI scanning.
2004 use_crs [X86] Use PCI host bridge window information
2005 from ACPI. On BIOSes from 2008 or later, this
2006 is enabled by default. If you need to use this,
2007 please report a bug.
2008 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2009 If you need to use this, please report a bug.
2010 routeirq Do IRQ routing for all PCI devices.
2011 This is normally done in pci_enable_device(),
2012 so this option is a temporary workaround
2013 for broken drivers that don't call it.
2014 skip_isa_align [X86] do not align io start addr, so can
2015 handle more pci cards
2016 firmware [ARM] Do not re-enumerate the bus but instead
2017 just use the configuration from the
2018 bootloader. This is currently used on
2019 IXP2000 systems where the bus has to be
2020 configured a certain way for adjunct CPUs.
2021 noearly [X86] Don't do any early type 1 scanning.
2022 This might help on some broken boards which
2023 machine check when some devices' config space
2024 is read. But various workarounds are disabled
2025 and some IOMMU drivers will not work.
2026 bfsort Sort PCI devices into breadth-first order.
2027 This sorting is done to get a device
2028 order compatible with older (<= 2.4) kernels.
2029 nobfsort Don't sort PCI devices into breadth-first order.
2030 cbiosize=nn[KMG] The fixed amount of bus space which is
2031 reserved for the CardBus bridge's IO window.
2032 The default value is 256 bytes.
2033 cbmemsize=nn[KMG] The fixed amount of bus space which is
2034 reserved for the CardBus bridge's memory
2035 window. The default value is 64 megabytes.
2038 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2039 Specifies alignment and device to reassign
2040 aligned memory resources.
2041 If <order of align> is not specified,
2042 PAGE_SIZE is used as alignment.
2043 PCI-PCI bridge can be specified, if resource
2044 windows need to be expanded.
2045 ecrc= Enable/disable PCIe ECRC (transaction layer
2046 end-to-end CRC checking).
2047 bios: Use BIOS/firmware settings. This is the
2052 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2055 force Enable ASPM even on devices that claim not to support it.
2056 WARNING: Forcing ASPM on may cause system lockups.
2058 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2059 Format: {auto|force}[,nomsi]
2060 auto Use native PCIe PME signaling if the BIOS allows the
2061 kernel to control PCIe config registers of root ports.
2062 force Use native PCIe PME signaling even if the BIOS refuses
2063 to allow the kernel to control the relevant PCIe config
2065 nomsi Do not use MSI for native PCIe PME signaling (this makes
2066 all PCIe root ports use INTx for everything).
2068 pcmv= [HW,PCMCIA] BadgePAD 4
2071 See Documentation/blockdev/paride.txt.
2073 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2076 See arch/parisc/kernel/pdc_chassis.c
2078 percpu_alloc= Select which percpu first chunk allocator to use.
2079 Currently supported values are "embed" and "page".
2080 Archs may support subset or none of the selections.
2081 See comments in mm/percpu.c for details on each
2082 allocator. This parameter is primarily for debugging
2083 and performance comparison.
2086 See Documentation/blockdev/paride.txt.
2089 See Documentation/blockdev/paride.txt.
2091 pirq= [SMP,APIC] Manual mp-table setup
2092 See Documentation/x86/i386/IO-APIC.txt.
2094 plip= [PPT,NET] Parallel port network link
2095 Format: { parport<nr> | timid | 0 }
2096 See also Documentation/parport.txt.
2098 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2099 Override pmtimer IOPort with a hex value.
2103 Enable PNP debug messages. This depends on the
2104 CONFIG_PNP_DEBUG_MESSAGES option.
2110 { on | off | curr | res | no-curr | no-res }
2113 [ISAPNP] Exclude IRQs for the autoconfiguration
2116 [ISAPNP] Exclude DMAs for the autoconfiguration
2118 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2119 Ranges are in pairs (I/O port base and size).
2122 [ISAPNP] Exclude memory regions for the
2124 Ranges are in pairs (memory base and size).
2126 ports= [IP_VS_FTP] IPVS ftp helper module
2128 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2130 Format: <port>,<port>....
2132 print-fatal-signals=
2133 [KNL] debug: print fatal signals
2135 If enabled, warn about various signal handling
2136 related application anomalies: too many signals,
2137 too many POSIX.1 timers, fatal signals causing a
2140 If you hit the warning due to signal overflow,
2141 you might want to try "ulimit -i unlimited".
2145 printk.time= Show timing data prefixed to each printk message line
2146 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2148 processor.max_cstate= [HW,ACPI]
2149 Limit processor to maximum C-state
2150 max_cstate=9 overrides any DMI blacklist limit.
2152 processor.nocst [HW,ACPI]
2153 Ignore the _CST method to determine C-states,
2154 instead using the legacy FADT method
2156 profile= [KNL] Enable kernel profiling via /proc/profile
2157 Format: [schedule,]<number>
2158 Param: "schedule" - profile schedule points.
2159 Param: <number> - step/bucket size as a power of 2 for
2160 statistical time based profiling.
2161 Param: "sleep" - profile D-state sleeping (millisecs).
2162 Requires CONFIG_SCHEDSTATS
2163 Param: "kvm" - profile VM exits.
2165 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2167 See Documentation/blockdev/ramdisk.txt.
2169 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2170 probe for; one of (bare|imps|exps|lifebook|any).
2171 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2173 psmouse.resetafter= [HW,MOUSE]
2174 Try to reset the device after so many bad packets
2177 [HW,MOUSE] Set desired mouse resolution, in dpi.
2178 psmouse.smartscroll=
2179 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2180 0 = disabled, 1 = enabled (default).
2182 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2184 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2187 See Documentation/blockdev/paride.txt.
2190 [KNL] Number of legacy pty's. Overwrites compiled-in
2193 quiet [KNL] Disable most log messages
2198 See Documentation/md.txt.
2200 ramdisk_blocksize= [RAM]
2201 See Documentation/blockdev/ramdisk.txt.
2203 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2204 See Documentation/blockdev/ramdisk.txt.
2206 rcupdate.blimit= [KNL,BOOT]
2207 Set maximum number of finished RCU callbacks to process
2210 rcupdate.qhimark= [KNL,BOOT]
2211 Set threshold of queued
2212 RCU callbacks over which batch limiting is disabled.
2214 rcupdate.qlowmark= [KNL,BOOT]
2215 Set threshold of queued RCU callbacks below which
2216 batch limiting is re-enabled.
2220 Run specified binary instead of /init from the ramdisk,
2221 used for early userspace startup. See initrd.
2223 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2224 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2225 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2228 [KNL, SMP] Set scheduler's default relax_domain_level.
2229 See Documentation/cgroups/cpusets.txt.
2231 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2233 reservetop= [X86-32]
2235 Reserves a hole at the top of the kernel virtual
2238 reset_devices [KNL] Force drivers to reset the underlying device
2239 during initialization.
2242 Specify the partition device for software suspend
2244 resume_offset= [SWSUSP]
2245 Specify the offset from the beginning of the partition
2246 given by "resume=" at which the swap header is located,
2247 in <PAGE_SIZE> units (needed only for swap files).
2248 See Documentation/power/swsusp-and-swap-files.txt
2250 retain_initrd [RAM] Keep initrd memory after extraction
2252 rhash_entries= [KNL,NET]
2253 Set number of hash buckets for route cache
2255 riscom8= [HW,SERIAL]
2256 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2258 ro [KNL] Mount root device read-only on boot
2260 root= [KNL] Root filesystem
2262 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2263 mount the root filesystem
2265 rootflags= [KNL] Set root filesystem mount option string
2267 rootfstype= [KNL] Set root filesystem type
2269 rootwait [KNL] Wait (indefinitely) for root device to show up.
2270 Useful for devices that are detected asynchronously
2271 (e.g. USB and MMC devices).
2273 rw [KNL] Mount root device read-write on boot
2275 S [KNL] Run init in single mode
2278 See drivers/net/irda/sa1100_ir.c.
2280 sbni= [NET] Granch SBNI12 leased line adapter
2282 sched_debug [KNL] Enables verbose scheduler debug messages.
2284 scsi_debug_*= [SCSI]
2285 See drivers/scsi/scsi_debug.c.
2287 scsi_default_dev_flags=
2288 [SCSI] SCSI default device flags
2291 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2292 Format: <vendor>:<model>:<flags>
2293 (flags are integer value)
2295 scsi_logging_level= [SCSI] a bit mask of logging levels
2296 See drivers/scsi/scsi_logging.h for bits. Also
2297 settable via sysctl at dev.scsi.logging_level
2298 (/proc/sys/dev/scsi/logging_level).
2299 There is also a nice 'scsi_logging_level' script in the
2300 S390-tools package, available for download at
2301 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2303 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2304 discovered. async scans them in kernel threads,
2305 allowing boot to proceed. none ignores them, expecting
2306 user space to do the scan.
2308 security= [SECURITY] Choose a security module to enable at boot.
2309 If this boot parameter is not specified, only the first
2310 security module asking for security registration will be
2311 loaded. An invalid security module name will be treated
2312 as if no module has been chosen.
2314 selinux= [SELINUX] Disable or enable SELinux at boot time.
2315 Format: { "0" | "1" }
2316 See security/selinux/Kconfig help text.
2319 Default value is set via kernel config option.
2320 If enabled at boot time, /selinux/disable can be used
2321 later to disable prior to initial policy load.
2323 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2324 Format: { "0" | "1" }
2325 See security/apparmor/Kconfig help text
2328 Default value is set via kernel config option.
2330 serialnumber [BUGS=X86-32]
2333 Maximal number of shapers.
2335 show_msr= [x86] show boot-time MSR settings
2336 Format: { <integer> }
2337 Show boot-time (BIOS-initialized) MSR settings.
2338 The parameter means the number of CPUs to show,
2339 for example 1 means boot CPU only.
2342 See header of drivers/scsi/sim710.c.
2349 slub_debug[=options[,slabs]] [MM, SLUB]
2350 Enabling slub_debug allows one to determine the
2351 culprit if slab objects become corrupted. Enabling
2352 slub_debug can create guard zones around objects and
2353 may poison objects when not in use. Also tracks the
2354 last alloc / free. For more information see
2355 Documentation/vm/slub.txt.
2357 slub_max_order= [MM, SLUB]
2358 Determines the maximum allowed order for slabs.
2359 A high setting may cause OOMs due to memory
2360 fragmentation. For more information see
2361 Documentation/vm/slub.txt.
2363 slub_min_objects= [MM, SLUB]
2364 The minimum number of objects per slab. SLUB will
2365 increase the slab order up to slub_max_order to
2366 generate a sufficiently large slab able to contain
2367 the number of objects indicated. The higher the number
2368 of objects the smaller the overhead of tracking slabs
2369 and the less frequently locks need to be acquired.
2370 For more information see Documentation/vm/slub.txt.
2372 slub_min_order= [MM, SLUB]
2373 Determines the mininum page order for slabs. Must be
2374 lower than slub_max_order.
2375 For more information see Documentation/vm/slub.txt.
2377 slub_nomerge [MM, SLUB]
2378 Disable merging of slabs with similar size. May be
2379 necessary if there is some reason to distinguish
2380 allocs to different slabs. Debug options disable
2381 merging on their own.
2382 For more information see Documentation/vm/slub.txt.
2385 Format: <io1>[,<io2>[,...,<io8>]]
2387 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2388 attempt to substitute SMP alternatives once at boot.
2390 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2391 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2392 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2393 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2394 smsc-ircc2.ircc_irq= [HW] IRQ line
2395 smsc-ircc2.ircc_dma= [HW] DMA channel
2396 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2397 0: Toshiba Satellite 1800 (GP data pin select)
2398 1: Fast pin select (default)
2401 snd-ad1816a= [HW,ALSA]
2403 snd-ad1848= [HW,ALSA]
2405 snd-ali5451= [HW,ALSA]
2407 snd-als100= [HW,ALSA]
2409 snd-als4000= [HW,ALSA]
2411 snd-azt2320= [HW,ALSA]
2413 snd-cmi8330= [HW,ALSA]
2415 snd-cmipci= [HW,ALSA]
2417 snd-cs4231= [HW,ALSA]
2419 snd-cs4232= [HW,ALSA]
2421 snd-cs4236= [HW,ALSA]
2423 snd-cs4281= [HW,ALSA]
2425 snd-cs46xx= [HW,ALSA]
2427 snd-dt019x= [HW,ALSA]
2429 snd-dummy= [HW,ALSA]
2431 snd-emu10k1= [HW,ALSA]
2433 snd-ens1370= [HW,ALSA]
2435 snd-ens1371= [HW,ALSA]
2437 snd-es968= [HW,ALSA]
2439 snd-es1688= [HW,ALSA]
2441 snd-es18xx= [HW,ALSA]
2443 snd-es1938= [HW,ALSA]
2445 snd-es1968= [HW,ALSA]
2447 snd-fm801= [HW,ALSA]
2449 snd-gusclassic= [HW,ALSA]
2451 snd-gusextreme= [HW,ALSA]
2453 snd-gusmax= [HW,ALSA]
2457 snd-ice1712= [HW,ALSA]
2459 snd-intel8x0= [HW,ALSA]
2461 snd-interwave= [HW,ALSA]
2466 snd-korg1212= [HW,ALSA]
2468 snd-maestro3= [HW,ALSA]
2470 snd-mpu401= [HW,ALSA]
2472 snd-mtpav= [HW,ALSA]
2474 snd-nm256= [HW,ALSA]
2476 snd-opl3sa2= [HW,ALSA]
2484 snd-opti93x= [HW,ALSA]
2488 snd-rme32= [HW,ALSA]
2490 snd-rme96= [HW,ALSA]
2492 snd-rme9652= [HW,ALSA]
2498 snd-sbawe= [HW,ALSA]
2500 snd-serial= [HW,ALSA]
2502 snd-sgalaxy= [HW,ALSA]
2504 snd-sonicvibes= [HW,ALSA]
2509 snd-sun-cs4231= [HW,ALSA]
2511 snd-trident= [HW,ALSA]
2513 snd-usb-audio= [HW,ALSA,USB]
2515 snd-via82xx= [HW,ALSA]
2517 snd-virmidi= [HW,ALSA]
2519 snd-wavefront= [HW,ALSA]
2521 snd-ymfpci= [HW,ALSA]
2524 [KNL] Should the soft-lockup detector generate panics.
2526 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2527 See Documentation/sonypi.txt
2529 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2530 See Documentation/serial/specialix.txt.
2532 spia_io_base= [HW,MTD]
2538 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2540 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2541 See Documentation/scsi/st.txt.
2544 Enabled the stack tracer on boot up.
2548 Set the STI (builtin display/keyboard on the HP-PARISC
2549 machines) console (graphic card) which should be used
2550 as the initial boot-console.
2551 See also comment in drivers/video/console/sticore.c.
2554 See comment in drivers/video/console/sticore.c.
2557 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2559 sunrpc.min_resvport=
2560 sunrpc.max_resvport=
2562 SunRPC servers often require that client requests
2563 originate from a privileged port (i.e. a port in the
2564 range 0 < portnr < 1024).
2565 An administrator who wishes to reserve some of these
2566 ports for other uses may adjust the range that the
2567 kernel's sunrpc client considers to be privileged
2568 using these two parameters to set the minimum and
2569 maximum port values.
2573 Control how the NFS server code allocates CPUs to
2574 service thread pools. Depending on how many NICs
2575 you have and where their interrupts are bound, this
2576 option will affect which CPUs will do NFS serving.
2577 Note: this parameter cannot be changed while the
2578 NFS server is running.
2580 auto the server chooses an appropriate mode
2581 automatically using heuristics
2582 global a single global pool contains all CPUs
2583 percpu one pool for each CPU
2584 pernode one pool for each NUMA node (equivalent
2585 to global on non-NUMA machines)
2587 sunrpc.tcp_slot_table_entries=
2588 sunrpc.udp_slot_table_entries=
2590 Sets the upper limit on the number of simultaneous
2591 RPC calls that can be sent from the client to a
2592 server. Increasing these values may allow you to
2593 improve throughput, but will also increase the
2594 amount of memory reserved for use by the client.
2596 swiotlb= [IA-64] Number of I/O TLB slabs
2600 sym53c416= [HW,SCSI]
2601 See header of drivers/scsi/sym53c416.c.
2603 sysrq_always_enabled
2605 Ignore sysrq setting - this boot parameter will
2606 neutralize any effect of /proc/sys/kernel/sysrq.
2607 Useful for debugging.
2610 See header of drivers/scsi/t128.c.
2614 test_suspend= [SUSPEND]
2615 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2616 standby suspend) as the system sleep state to briefly
2617 enter during system startup. The system is woken from
2618 this state using a wakeup-capable RTC alarm.
2620 thash_entries= [KNL,NET]
2621 Set number of hash buckets for TCP connection
2623 thermal.act= [HW,ACPI]
2624 -1: disable all active trip points in all thermal zones
2625 <degrees C>: override all lowest active trip points
2627 thermal.crt= [HW,ACPI]
2628 -1: disable all critical trip points in all thermal zones
2629 <degrees C>: override all critical trip points
2631 thermal.nocrt= [HW,ACPI]
2632 Set to disable actions on ACPI thermal zone
2633 critical and hot trip points.
2635 thermal.off= [HW,ACPI]
2636 1: disable ACPI thermal control
2638 thermal.psv= [HW,ACPI]
2639 -1: disable all passive trip points
2640 <degrees C>: override all passive trip points to this
2643 thermal.tzp= [HW,ACPI]
2644 Specify global default ACPI thermal zone polling rate
2645 <deci-seconds>: poll all this frequency
2646 0: no polling (default)
2649 See comment before function dc390_setup() in
2650 drivers/scsi/tmscsim.c.
2654 Specify if the kernel should make use of the cpu
2655 topology informations if the hardware supports these.
2656 The scheduler will make use of these informations and
2657 e.g. base its process migration decisions on it.
2662 tpm_suspend_pcr=[HW,TPM]
2663 Format: integer pcr id
2664 Specify that at suspend time, the tpm driver
2665 should extend the specified pcr with zeros,
2666 as a workaround for some chips which fail to
2667 flush the last written pcr on TPM_SaveState.
2668 This will guarantee that all the other pcrs
2671 trace_buf_size=nn[KMG]
2672 [FTRACE] will set tracing buffer size.
2674 trace_event=[event-list]
2675 [FTRACE] Set and start specified trace events in order
2676 to facilitate early boot debugging.
2677 See also Documentation/trace/events.txt
2679 trix= [HW,OSS] MediaTrix AudioTrix Pro
2681 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2683 tsc= Disable clocksource-must-verify flag for TSC.
2685 [x86] reliable: mark tsc clocksource as reliable, this
2686 disables clocksource verification at runtime.
2687 Used to enable high-resolution timer mode on older
2688 hardware, and in virtualized environment.
2690 turbografx.map[2|3]= [HW,JOY]
2691 TurboGraFX parallel port interface
2693 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2694 See also Documentation/input/joystick-parport.txt
2696 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2697 See header of drivers/scsi/u14-34f.c.
2705 uhash_entries= [KNL,NET]
2706 Set number of hash buckets for UDP/UDP-Lite connections
2709 [USB] Ignore overcurrent events (default N).
2710 Some badly-designed motherboards generate lots of
2711 bogus events, for ports that aren't wired to
2712 anything. Set this parameter to avoid log spamming.
2713 Note that genuine overcurrent events won't be
2718 Set unknown_nmi_panic=1 early on boot.
2720 usbcore.autosuspend=
2721 [USB] The autosuspend time delay (in seconds) used
2722 for newly-detected USB devices (default 2). This
2723 is the time required before an idle device will be
2724 autosuspended. Devices for which the delay is set
2725 to a negative value won't be autosuspended at all.
2727 usbcore.usbfs_snoop=
2728 [USB] Set to log all usbfs traffic (default 0 = off).
2730 usbcore.blinkenlights=
2731 [USB] Set to cycle leds on hubs (default 0 = off).
2733 usbcore.old_scheme_first=
2734 [USB] Start with the old device initialization
2735 scheme (default 0 = off).
2737 usbcore.use_both_schemes=
2738 [USB] Try the other device initialization scheme
2739 if the first one fails (default 1 = enabled).
2741 usbcore.initial_descriptor_timeout=
2742 [USB] Specifies timeout for the initial 64-byte
2743 USB_REQ_GET_DESCRIPTOR request in milliseconds
2744 (default 5000 = 5.0 seconds).
2747 [USBHID] The interval which mice are to be polled at.
2749 usb-storage.delay_use=
2750 [UMS] The delay in seconds before a new device is
2751 scanned for Logical Units (default 5).
2754 [UMS] A list of quirks entries to supplement or
2755 override the built-in unusual_devs list. List
2756 entries are separated by commas. Each entry has
2757 the form VID:PID:Flags where VID and PID are Vendor
2758 and Product ID values (4-digit hex numbers) and
2759 Flags is a set of characters, each corresponding
2760 to a common usb-storage quirk flag as follows:
2761 a = SANE_SENSE (collect more than 18 bytes
2763 b = BAD_SENSE (don't collect more than 18
2764 bytes of sense data);
2765 c = FIX_CAPACITY (decrease the reported
2766 device capacity by one sector);
2767 h = CAPACITY_HEURISTICS (decrease the
2768 reported device capacity by one
2769 sector if the number is odd);
2770 i = IGNORE_DEVICE (don't bind to this
2772 l = NOT_LOCKABLE (don't try to lock and
2773 unlock ejectable media);
2774 m = MAX_SECTORS_64 (don't transfer more
2775 than 64 sectors = 32 KB at a time);
2776 o = CAPACITY_OK (accept the capacity
2777 reported by the device);
2778 r = IGNORE_RESIDUE (the device reports
2779 bogus residue values);
2780 s = SINGLE_LUN (the device has only one
2782 w = NO_WP_DETECT (don't test whether the
2783 medium is write-protected).
2784 Example: quirks=0419:aaf5:rl,0421:0433:rc
2787 [X86] Flags controlling user PTE allocations.
2789 nohigh = do not allocate PTE pages in
2790 HIGHMEM regardless of setting
2794 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2795 vdso=1: enable VDSO (default)
2796 vdso=0: disable VDSO mapping
2799 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2800 vdso32=1: enable 32-bit VDSO (default)
2801 vdso32=0: disable 32-bit VDSO mapping
2804 vector=percpu: enable percpu vector domain
2806 video= [FB] Frame buffer configuration
2807 See Documentation/fb/modedb.txt.
2809 vga= [BOOT,X86-32] Select a particular video mode
2810 See Documentation/x86/boot.txt and
2811 Documentation/svga.txt.
2812 Use vga=ask for menu.
2813 This is actually a boot loader parameter; the value is
2814 passed to the kernel using a special protocol.
2816 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2817 size of <nn>. This can be used to increase the
2818 minimum size (128MB on x86). It can also be used to
2819 decrease the size and leave more room for directly
2822 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2825 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2828 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2831 vt.cur_default= [VT] Default cursor shape.
2832 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2833 the parameters of the <Esc>[?A;B;Cc escape sequence;
2834 see VGA-softcursor.txt. Default: 2 = underline.
2836 vt.default_blu= [VT]
2837 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2838 Change the default blue palette of the console.
2839 This is a 16-member array composed of values
2842 vt.default_grn= [VT]
2843 Format: <green0>,<green1>,<green2>,...,<green15>
2844 Change the default green palette of the console.
2845 This is a 16-member array composed of values
2848 vt.default_red= [VT]
2849 Format: <red0>,<red1>,<red2>,...,<red15>
2850 Change the default red palette of the console.
2851 This is a 16-member array composed of values
2857 Set system-wide default UTF-8 mode for all tty's.
2858 Default is 1, i.e. UTF-8 mode is enabled for all
2859 newly opened terminals.
2861 vt.global_cursor_default=
2864 Set system-wide default for whether a cursor
2865 is shown on new VTs. Default is -1,
2866 i.e. cursors will be created by default unless
2867 overridden by individual drivers. 0 will hide
2868 cursors, 1 will display them.
2870 waveartist= [HW,OSS]
2871 Format: <io>,<irq>,<dma>,<dma2>
2874 See header of drivers/scsi/wd33c93.c.
2877 See header of drivers/scsi/wd7000.c.
2879 watchdog timers [HW,WDT] For information on watchdog timers,
2880 see Documentation/watchdog/watchdog-parameters.txt
2881 or other driver-specific files in the
2882 Documentation/watchdog/ directory.
2884 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2885 default x2apic cluster mode on platforms
2888 x86_mrst_timer= [X86-32,APBT]
2889 Choose timer option for x86 Moorestown MID platform.
2890 Two valid options are apbt timer only and lapic timer
2891 plus one apbt timer for broadcast timer.
2892 x86_mrst_timer=apbt_only | lapic_and_apbt
2894 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2895 xd_geo= See header of drivers/block/xd.c.
2897 xen_emul_unplug= [HW,X86,XEN]
2898 Unplug Xen emulated devices
2899 Format: [unplug0,][unplug1]
2900 ide-disks -- unplug primary master IDE devices
2901 aux-ide-disks -- unplug non-primary-master IDE devices
2902 nics -- unplug network devices
2903 all -- unplug all emulated devices (NICs and IDE disks)
2904 ignore -- continue loading the Xen platform PCI driver even
2905 if the version check failed
2907 xirc2ps_cs= [NET,PCMCIA]
2909 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2911 ______________________________________________________________________
2915 Add documentation for ALSA options.
2916 Add more DRM drivers.