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 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
78 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
80 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
82 PCIE PCI Express support is enabled.
83 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
93 SECURITY Different security models are enabled.
94 SELINUX SELinux support is enabled.
95 APPARMOR AppArmor support is enabled.
96 SERIAL Serial support is enabled.
97 SH SuperH architecture is enabled.
98 SMP The kernel is an SMP kernel.
99 SPARC Sparc architecture is enabled.
100 SWSUSP Software suspend (hibernation) is enabled.
101 SUSPEND System suspend states are enabled.
102 FTRACE Function tracing enabled.
103 TPM TPM drivers are enabled.
104 TS Appropriate touchscreen support is enabled.
105 UMS USB Mass Storage support is enabled.
106 USB USB support is enabled.
107 USBHID USB Human Interface Device support is enabled.
108 V4L Video For Linux support is enabled.
109 VGA The VGA console has been enabled.
110 VT Virtual terminal support is enabled.
111 WDT Watchdog support is enabled.
112 XT IBM PC/XT MFM hard disk support is enabled.
113 X86-32 X86-32, aka i386 architecture is enabled.
114 X86-64 X86-64 architecture is enabled.
115 More X86-64 boot options can be found in
116 Documentation/x86/x86_64/boot-options.txt .
117 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
118 XEN Xen support is enabled
120 In addition, the following text indicates that the option:
122 BUGS= Relates to possible processor bugs on the said processor.
123 KNL Is a kernel start-up parameter.
124 BOOT Is a boot loader parameter.
126 Parameters denoted with BOOT are actually interpreted by the boot
127 loader, and have no meaning to the kernel directly.
128 Do not modify the syntax of boot loader parameters without extreme
129 need or coordination with <Documentation/x86/boot.txt>.
131 There are also arch-specific kernel-parameters not documented here.
132 See for example <Documentation/x86/x86_64/boot-options.txt>.
134 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
135 a trailing = on the name of any parameter states that that parameter will
136 be entered as an environment variable, whereas its absence indicates that
137 it will appear as a kernel argument readable via /proc/cmdline by programs
138 running once the system is up.
140 The number of kernel parameters is not limited, but the length of the
141 complete command line (parameters including spaces etc.) is limited to
142 a fixed number of characters. This limit depends on the architecture
143 and is between 256 and 4096 characters. It is defined in the file
144 ./include/asm/setup.h as COMMAND_LINE_SIZE.
148 Advanced Configuration and Power Interface
149 Format: { force | off | strict | noirq | rsdt }
150 force -- enable ACPI if default was off
151 off -- disable ACPI if default was on
152 noirq -- do not use ACPI for IRQ routing
153 strict -- Be less tolerant of platforms that are not
154 strictly ACPI specification compliant.
155 rsdt -- prefer RSDT over (default) XSDT
156 copy_dsdt -- copy DSDT to memory
158 See also Documentation/power/pm.txt, pci=noacpi
160 acpi_apic_instance= [ACPI, IOAPIC]
162 2: use 2nd APIC table, if available
163 1,0: use 1st APIC table
166 acpi_backlight= [HW,ACPI]
167 acpi_backlight=vendor
169 If set to vendor, prefer vendor specific driver
170 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
171 of the ACPI video.ko driver.
173 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
174 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
176 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
177 debug output. Bits in debug_layer correspond to a
178 _COMPONENT in an ACPI source file, e.g.,
179 #define _COMPONENT ACPI_PCI_COMPONENT
180 Bits in debug_level correspond to a level in
181 ACPI_DEBUG_PRINT statements, e.g.,
182 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
183 The debug_level mask defaults to "info". See
184 Documentation/acpi/debug.txt for more information about
185 debug layers and levels.
187 Enable processor driver info messages:
188 acpi.debug_layer=0x20000000
189 Enable PCI/PCI interrupt routing info messages:
190 acpi.debug_layer=0x400000
191 Enable AML "Debug" output, i.e., stores to the Debug
192 object while interpreting AML:
193 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
194 Enable all messages related to ACPI hardware:
195 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
197 Some values produce so much output that the system is
198 unusable. The "log_buf_len" parameter may be useful
199 if you need to capture more output.
201 acpi_display_output= [HW,ACPI]
202 acpi_display_output=vendor
203 acpi_display_output=video
206 acpi_irq_balance [HW,ACPI]
207 ACPI will balance active IRQs
210 acpi_irq_nobalance [HW,ACPI]
211 ACPI will not move active IRQs (default)
214 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
215 Format: <irq>,<irq>...
217 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
219 Format: <irq>,<irq>...
221 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
223 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
224 Format: To spoof as Windows 98: ="Microsoft Windows"
226 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
227 acpi_osi="string1" # add string1 -- only one string
228 acpi_osi="!string2" # remove built-in string2
229 acpi_osi= # disable all strings
232 Override the pmtimer bug detection: force the kernel
233 to assume that this machine's pmtimer latches its value
234 and always returns good values.
236 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
237 Format: { level | edge | high | low }
239 acpi_serialize [HW,ACPI] force serialization of AML methods
241 acpi_skip_timer_override [HW,ACPI]
242 Recognize and ignore IRQ0/pin2 Interrupt Override.
243 For broken nForce2 BIOS resulting in XT-PIC timer.
245 acpi_sleep= [HW,ACPI] Sleep options
246 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
247 old_ordering, s4_nonvs, sci_force_enable }
248 See Documentation/power/video.txt for information on
250 s3_beep is for debugging; it makes the PC's speaker beep
251 as soon as the kernel's real-mode entry point is called.
252 s4_nohwsig prevents ACPI hardware signature from being
253 used during resume from hibernation.
254 old_ordering causes the ACPI 1.0 ordering of the _PTS
255 control method, with respect to putting devices into
256 low power states, to be enforced (the ACPI 2.0 ordering
257 of _PTS is used by default).
258 nonvs prevents the kernel from saving/restoring the
259 ACPI NVS memory during suspend/hibernation and resume.
260 sci_force_enable causes the kernel to set SCI_EN directly
261 on resume from S1/S3 (which is against the ACPI spec,
262 but some broken systems don't work without it).
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
291 See header of drivers/scsi/advansys.c.
293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
298 { off | try_unsupported }
299 off: disable AGP support
300 try_unsupported: try to drive unsupported chipsets
301 (may crash computer or cause data corruption)
304 See Documentation/scsi/aha152x.txt.
307 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
310 See Documentation/scsi/aic7xxx.txt.
313 See Documentation/scsi/aic79xx.txt.
316 Allow the default userspace alignment fault handler
317 behaviour to be specified. Bit 0 enables warnings,
318 bit 1 enables fixups, and bit 2 sends a segfault.
320 amd_iommu= [HW,X86-84]
321 Pass parameters to the AMD IOMMU driver in the system.
323 fullflush - enable flushing of IO/TLB entries when
324 they are unmapped. Otherwise they are
325 flushed before they will be reused, which
327 off - do not initialize any AMD IOMMU found in
330 amijoy.map= [HW,JOY] Amiga joystick support
331 Map of devices attached to JOY0DAT and JOY1DAT
333 See also Documentation/kernel/input/joystick.txt
335 analog.map= [HW,JOY] Analog joystick and gamepad support
336 Specifies type or capabilities of an analog joystick
337 connected to one of 16 gameports
338 Format: <type1>,<type2>,..<type16>
341 Power management functions (SPARCstation-4/5 + deriv.)
343 Disable APC CPU standby support. SPARCstation-Fox does
344 not play well with APC CPU idle - disable it if you have
345 APC and your system crashes randomly.
347 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
348 Change the output verbosity whilst booting
349 Format: { quiet (default) | verbose | debug }
350 Change the amount of debugging information output
351 when initialising the APIC and IO-APIC components.
354 See Documentation/networking/ipv6.txt.
356 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
357 Limit apic dumping. The parameter defines the maximal
358 number of local apics being dumped. Also it is possible
359 to set it to "all" by meaning -- no limit here.
360 Format: { 1 (default) | 2 | ... | all }.
361 The parameter valid if only apic=debug or
362 apic=verbose is specified.
363 Example: apic=debug show_lapic=all
365 apm= [APM] Advanced Power Management
366 See header of arch/x86/kernel/apm_32.c.
368 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
369 Format: <io>,<irq>,<nodeID>
373 atarimouse= [HW,MOUSE] Atari Mouse
375 atascsi= [HW,SCSI] Atari SCSI
377 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
378 EzKey and similar keyboards
380 atkbd.reset= [HW] Reset keyboard during initialization
382 atkbd.set= [HW] Select keyboard code set
383 Format: <int> (2 = AT (default), 3 = PS/2)
385 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
388 atkbd.softraw= [HW] Choose between synthetic and real raw mode
389 Format: <bool> (0 = real, 1 = synthetic (default))
391 atkbd.softrepeat= [HW]
392 Use software keyboard repeat
396 baycom_epp= [HW,AX25]
399 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
401 See header of drivers/net/hamradio/baycom_par.c.
403 baycom_ser_fdx= [HW,AX25]
404 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
405 Format: <io>,<irq>,<mode>[,<baud>]
406 See header of drivers/net/hamradio/baycom_ser_fdx.c.
408 baycom_ser_hdx= [HW,AX25]
409 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
410 Format: <io>,<irq>,<mode>
411 See header of drivers/net/hamradio/baycom_ser_hdx.c.
413 boot_delay= Milliseconds to delay each printk during boot.
414 Values larger than 10 seconds (10000) are changed to
418 bootmem_debug [KNL] Enable bootmem allocator debug messages.
420 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
421 bttv.radio= Most important insmod options are available as
423 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
424 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
427 See drivers/scsi/BusLogic.c, comment before function
428 BusLogic_ParseDriverOptions().
430 c101= [NET] Moxa C101 synchronous serial card
432 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
433 Sometimes CPU hardware bugs make them report the cache
434 size incorrectly. The kernel will attempt work arounds
435 to fix known problems, but for some CPUs it is not
436 possible to determine what the correct size should be.
437 This option provides an override for these situations.
440 [SECURITY] Disable capabilities. This would normally
441 be used only if an alternative security model is to be
442 configured. Potentially dangerous and should only be
443 used if you are entirely sure of the consequences.
445 ccw_timeout_log [S390]
446 See Documentation/s390/CommonIO for details.
448 cgroup_disable= [KNL] Disable a particular controller
449 Format: {name of the controller(s) to disable}
450 {Currently supported controllers - "memory"}
452 checkreqprot [SELINUX] Set initial checkreqprot flag value.
453 Format: { "0" | "1" }
454 See security/selinux/Kconfig help text.
455 0 -- check protection applied by kernel (includes
456 any implied execute protection).
457 1 -- check protection requested by application.
458 Default value is set via a kernel config option.
459 Value can be changed at runtime via
460 /selinux/checkreqprot.
463 See Documentation/s390/CommonIO for details.
465 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
467 Forces specified clocksource (if available) to be used
468 when calculating gettimeofday(). If specified
469 clocksource is not available, it defaults to PIT.
470 Format: { pit | tsc | cyclone | pmtmr }
472 clocksource= Override the default clocksource
474 Override the default clocksource and use the clocksource
475 with the name specified.
476 Some clocksource names to choose from, depending on
478 [all] jiffies (this is the base, fallback clocksource)
480 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
481 pxa_timer,timer3,32k_counter,timer0_1
483 [X86-32] pit,hpet,tsc,vmi-timer;
484 scx200_hrt on Geode; cyclone on IBM x440
492 clearcpuid=BITNUM [X86]
493 Disable CPUID feature X for the kernel. See
494 arch/x86/include/asm/cpufeature.h for the valid bit
495 numbers. Note the Linux specific bits are not necessarily
496 stable over kernel options, but the vendor specific
498 Also note that user programs calling CPUID directly
499 or using the feature without checking anything
500 will still see it. This just prevents it from
501 being used by the kernel or shown in /proc/cpuinfo.
502 Also note the kernel might malfunction if you disable
505 cmo_free_hint= [PPC] Format: { yes | no }
506 Specify whether pages are marked as being inactive
507 when they are freed. This is used in CMO environments
508 to determine OS memory pressure for page stealing by
512 code_bytes [X86] How many bytes of object code to print
517 com20020= [HW,NET] ARCnet - COM20020 chipset
519 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
521 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
525 ARCnet - COM90xx chipset (memory-mapped buffers)
526 Format: <io>[,<irq>[,<memstart>]]
528 condev= [HW,S390] console device
531 console= [KNL] Output console device and options.
533 tty<n> Use the virtual console device <n>.
537 Use the specified serial port. The options are of
538 the form "bbbbpnf", where "bbbb" is the baud rate,
539 "p" is parity ("n", "o", or "e"), "n" is number of
540 bits, and "f" is flow control ("r" for RTS or
541 omit it). Default is "9600n8".
543 See Documentation/serial-console.txt for more
545 Documentation/networking/netconsole.txt for an
548 uart[8250],io,<addr>[,options]
549 uart[8250],mmio,<addr>[,options]
550 Start an early, polled-mode console on the 8250/16550
551 UART at the specified I/O port or MMIO address,
552 switching to the matching ttyS device later. The
553 options are the same as for ttyS, above.
555 If the device connected to the port is not a TTY but a braille
556 device, prepend "brl," before the device type, for instance
558 For now, only VisioBraille is supported.
560 consoleblank= [KNL] The console blank (screen saver) timeout in
561 seconds. Defaults to 10*60 = 10mins. A value of 0
562 disables the blank timer.
565 [KNL] Change the default value for
566 /proc/<pid>/coredump_filter.
567 See also Documentation/filesystems/proc.txt.
569 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
571 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
573 crashkernel=nn[KMG]@ss[KMG]
574 [KNL] Reserve a chunk of physical memory to
575 hold a kernel to switch to with kexec on panic.
577 crashkernel=range1:size1[,range2:size2,...][@offset]
578 [KNL] Same as above, but depends on the memory
579 in the running system. The syntax of range is
580 start-[end] where start and end are both
581 a memory unit (amount[KMG]). See also
582 Documentation/kdump/kdump.txt for a example.
587 cs89x0_media= [HW,NET]
588 Format: { rj45 | aui | bnc }
591 See header of drivers/s390/block/dasd_devmap.c.
593 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
594 (one device per port)
595 Format: <port#>,<type>
596 See also Documentation/input/joystick-parport.txt
598 debug [KNL] Enable kernel debugging (events log level).
601 [KNL] verbose self-tests
603 Print debugging info while doing the locking API
605 We default to 0 (no extra messages), setting it to
606 1 will print _a lot_ more information - normally
607 only useful to kernel developers.
609 debug_objects [KNL] Enable object debugging
612 [KNL] Disable object debugging
614 debugpat [X86] Enable PAT debugging
616 decnet.addr= [HW,NET]
617 Format: <area>[,<node>]
618 See also Documentation/networking/decnet.txt.
621 [same as hugepagesz=] The size of the default
622 HugeTLB page size. This is the size represented by
623 the legacy /proc/ hugepages APIs, used for SHM, and
624 default size when mounting hugetlbfs filesystems.
625 Defaults to the default architecture's huge page size
629 Set number of hash buckets for dentry cache.
632 IO parameters + enable/disable command.
634 digiepca= [HW,SERIAL]
635 See drivers/char/README.epca and
636 Documentation/serial/digiepca.txt.
639 See Documentation/networking/ipv6.txt.
642 See Documentation/networking/ipv6.txt.
644 disable_mtrr_cleanup [X86]
645 The kernel tries to adjust MTRR layout from continuous
646 to discrete, to make X server driver able to add WB
647 entry later. This parameter disables that.
649 disable_mtrr_trim [X86, Intel and AMD only]
650 By default the kernel will trim any uncacheable
651 memory out of your available memory pool based on
652 MTRR settings. This parameter disables that behavior,
653 possibly causing your machine to run very slowly.
655 disable_timer_pin_1 [X86]
656 Disable PIN 1 of APIC timer
657 Can be useful to work around chipset bugs.
659 dmasound= [HW,OSS] Sound subsystem buffers
661 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
662 this option disables the debugging code at boot.
664 dma_debug_entries=<number>
665 This option allows to tune the number of preallocated
666 entries for DMA-API debugging code. One entry is
667 required per DMA-API allocation. Use this if the
668 DMA-API debugging code disables itself because the
669 architectural default is too low.
671 dma_debug_driver=<driver_name>
672 With this option the DMA-API debugging driver
673 filter feature can be enabled at boot time. Just
674 pass the driver to filter for as the parameter.
675 The filter can be disabled or changed to another
676 driver later using sysfs.
682 dynamic_printk Enables pr_debug()/dev_dbg() calls if
683 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
684 These can also be switched on/off via
685 <debugfs>/dynamic_printk/modules
687 earlycon= [KNL] Output early console device and options.
688 uart[8250],io,<addr>[,options]
689 uart[8250],mmio,<addr>[,options]
690 Start an early, polled-mode console on the 8250/16550
691 UART at the specified I/O port or MMIO address.
692 The options are the same as for ttyS, above.
694 earlyprintk= [X86,SH,BLACKFIN]
696 earlyprintk=serial[,ttySn[,baudrate]]
697 earlyprintk=ttySn[,baudrate]
698 earlyprintk=dbgp[debugController#]
700 Append ",keep" to not disable it when the real console
703 Only vga or serial or usb debug port at a time.
705 Currently only ttyS0 and ttyS1 are supported.
707 Interaction with the standard serial driver is not
710 The VGA output is eventually overwritten by the real
713 ekgdboc= [X86,KGDB] Allow early kernel console debugging
716 This is desgined to be used in conjunction with
717 the boot argument: earlyprintk=vga
722 Format: {"off" | "on" | "skip[mbr]"}
724 eisa_irq_edge= [PARISC,HW]
725 See header of drivers/parisc/eisa.c.
728 See comment before function elanfreq_setup() in
729 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
732 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
733 See Documentation/block/as-iosched.txt and
734 Documentation/block/deadline-iosched.txt for details.
736 elfcorehdr= [IA64,PPC,SH,X86]
737 Specifies physical address of start of kernel core
738 image elf header. Generally kexec loader will
739 pass this option to capture kernel.
740 See Documentation/kdump/kdump.txt for details.
742 enable_mtrr_cleanup [X86]
743 The kernel tries to adjust MTRR layout from continuous
744 to discrete, to make X server driver able to add WB
745 entry later. This parameter enables that.
747 enable_timer_pin_1 [X86]
748 Enable PIN 1 of APIC timer
749 Can be useful to work around chipset bugs
750 (in particular on some ATI chipsets).
751 The kernel tries to set a reasonable default.
753 enforcing [SELINUX] Set initial enforcing status.
755 See security/selinux/Kconfig help text.
756 0 -- permissive (log only, no denials).
757 1 -- enforcing (deny and log).
759 Value can be changed at runtime via /selinux/enforce.
762 Disable Error Record Serialization Table (ERST)
765 ether= [HW,NET] Ethernet cards parameters
766 This option is obsoleted by the "netdev=" option, which
767 has equivalent usage. See its documentation for details.
771 fail_make_request=[KNL]
772 General fault injection mechanism.
773 Format: <interval>,<probability>,<space>,<times>
774 See also /Documentation/fault-injection/.
777 See header of drivers/scsi/fd_mcs.c.
780 See header of drivers/scsi/fdomain.c.
783 See Documentation/blockdev/floppy.txt.
785 force_pal_cache_flush
786 [IA-64] Avoid check_sal_cache_flush which may hang on
787 buggy SAL_CACHE_FLUSH implementations. Using this
788 parameter will force ia64_sal_cache_flush to call
789 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
792 [FTRACE] will set and start the specified tracer
793 as early as possible in order to facilitate early
796 ftrace_dump_on_oops[=orig_cpu]
797 [FTRACE] will dump the trace buffers on oops.
798 If no parameter is passed, ftrace will dump
799 buffers of all CPUs, but if you pass orig_cpu, it will
800 dump only the buffer of the CPU that triggered the
803 ftrace_filter=[function-list]
804 [FTRACE] Limit the functions traced by the function
805 tracer at boot up. function-list is a comma separated
806 list of functions. This list can be changed at run
807 time by the set_ftrace_filter file in the debugfs
810 ftrace_notrace=[function-list]
811 [FTRACE] Do not trace the functions specified in
812 function-list. This list can be changed at run time
813 by the set_ftrace_notrace file in the debugfs
816 ftrace_graph_filter=[function-list]
817 [FTRACE] Limit the top level callers functions traced
818 by the function graph tracer at boot up.
819 function-list is a comma separated list of functions
820 that can be changed at run time by the
821 set_graph_function file in the debugfs tracing directory.
824 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
825 support via parallel port (up to 5 devices per port)
826 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
827 See also Documentation/input/joystick-parport.txt
831 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
835 gcov_persist= [GCOV] When non-zero (default), profiling data for
836 kernel modules is saved and remains accessible via
837 debugfs, even when the module is unloaded/reloaded.
838 When zero, profiling data is discarded and associated
839 debugfs files are removed at module unload time.
842 See header of drivers/scsi/gdth.c.
844 gpt [EFI] Forces disk with valid GPT signature but
845 invalid Protective MBR to be treated as GPT.
849 hashdist= [KNL,NUMA] Large hashes allocated during boot
850 are distributed across NUMA nodes. Defaults on
851 for 64bit NUMA, off otherwise.
852 Format: 0 | 1 (for off | on)
854 hcl= [IA-64] SGI's Hardware Graph compatibility layer
856 hd= [EIDE] (E)IDE hard drive subsystem geometry
857 Format: <cyl>,<head>,<sect>
860 Disable Hardware Error Source Table (HEST) support;
861 corresponding firmware-first mode error processing
862 logic will be disabled.
864 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
865 size of <nn>. This works even on boxes that have no
866 highmem otherwise. This also works to reduce highmem
867 size on bigger boxes.
869 highres= [KNL] Enable/disable high resolution timer mode.
870 Valid parameters: "on", "off"
874 See Documentation/isdn/README.HiSax.
878 hpet= [X86-32,HPET] option to control HPET usage
879 Format: { enable (default) | disable | force |
881 disable: disable HPET and use PIT instead
882 force: allow force enabled of undocumented chips (ICH4,
884 verbose: show contents of HPET registers during setup
886 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
887 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
888 On x86-64 and powerpc, this option can be specified
889 multiple times interleaved with hugepages= to reserve
890 huge pages of different sizes. Valid pages sizes on
891 x86-64 are 2M (when the CPU supports "pse") and 1G
892 (when the CPU supports the "pdpe1gb" cpuinfo flag)
893 Note that 1GB pages can only be allocated at boot time
894 using hugepages= and not freed afterwards.
896 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
897 terminal devices. Valid values: 0..8
898 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
899 If specified, z/VM IUCV HVC accepts connections
900 from listed z/VM user IDs only.
902 i2c_bus= [HW] Override the default board specific I2C bus speed
903 or register an additional I2C bus that is not
904 registered from board initialization code.
908 i8042.debug [HW] Toggle i8042 debug mode
909 i8042.direct [HW] Put keyboard port into non-translated mode
910 i8042.dumbkbd [HW] Pretend that controller can only read data from
911 keyboard and cannot control its state
912 (Don't attempt to blink the leds)
913 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
914 i8042.nokbd [HW] Don't check/create keyboard port
915 i8042.noloop [HW] Disable the AUX Loopback command while probing
917 i8042.nomux [HW] Don't check presence of an active multiplexing
919 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
922 [HW] Frequency with which keyboard LEDs should blink
923 when kernel panics (default is 0.5 sec)
924 i8042.reset [HW] Reset the controller during init and cleanup
925 i8042.unlock [HW] Unlock (ignore) the keylock
929 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
930 indicates that the driver is running on unsupported
932 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
933 does not match list of supported models.
935 [HW] Report power status in /proc/i8k
936 (disabled by default)
937 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
940 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
941 See Documentation/mca.txt.
944 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
946 ide-core.nodma= [HW] (E)IDE subsystem
947 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
948 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
949 .cdrom .chs .ignore_cable are additional options
950 See Documentation/ide/ide.txt.
952 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
953 Claim all unknown PCI IDE storage controllers.
956 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
957 Poll forces a polling idle loop that can slightly
958 improve the performance of waking up a idle CPU, but
959 will use a lot of power and make the system run hot.
961 idle=mwait: On systems which support MONITOR/MWAIT but
962 the kernel chose to not use it because it doesn't save
963 as much power as a normal idle loop, use the
964 MONITOR/MWAIT idle loop anyways. Performance should be
965 the same as idle=poll.
966 idle=halt: Halt is forced to be used for CPU idle.
967 In such case C2/C3 won't be used again.
968 idle=nomwait: Disable mwait for CPU C-states
970 ignore_loglevel [KNL]
971 Ignore loglevel setting - this will print /all/
972 kernel messages to the console. Useful for debugging.
975 Set number of hash buckets for inode cache.
978 Format: { "0" | "1" }
979 0 -- integrity auditing messages. (Default)
980 1 -- enable informational integrity auditing messages.
983 Format: { "sha1" | "md5" }
987 Load a policy which meets the needs of the Trusted
988 Computing Base. This means IMA will measure all
989 programs exec'd, files mmap'd for exec, and all files
990 opened for read by uid=0.
993 See header of drivers/scsi/in2000.c.
997 Run specified binary instead of /sbin/init as init
1000 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1001 for working out where the kernel is dying during
1004 initrd= [BOOT] Specify the location of the initial ramdisk
1006 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1009 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1011 Enable intel iommu driver.
1013 Disable intel iommu driver.
1014 igfx_off [Default Off]
1015 By default, gfx is mapped as normal device. If a gfx
1016 device has a dedicated DMAR unit, the DMAR unit is
1017 bypassed by not enabling DMAR with this option. In
1018 this case, gfx device will use physical address for
1021 With this option iommu will not optimize to look
1022 for io virtual address below 32 bit forcing dual
1023 address cycle on pci bus for cards supporting greater
1024 than 32 bit addressing. The default is to look
1025 for translation below 32 bit and if not available
1026 then look in the higher range.
1027 strict [Default Off]
1028 With this option on every unmap_single operation will
1029 result in a hardware IOTLB flush operation as opposed
1030 to batching them for performance.
1034 iomem= Disable strict checking of access to MMIO memory
1035 strict regions from userspace.
1051 io7= [HW] IO7 for Marvel based alpha systems
1052 See comment before marvel_specify_io7 in
1053 arch/alpha/kernel/core_marvel.c.
1055 io_delay= [X86] I/O delay method
1057 Standard port 0x80 based delay
1059 Alternate port 0xed based delay (needed on some systems)
1061 Simple two microseconds delay
1066 See Documentation/filesystems/nfs/nfsroot.txt.
1068 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1069 See comment before ip2_setup() in
1070 drivers/char/ip2/ip2base.c.
1072 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1073 See header of drivers/scsi/ips.c.
1076 When an interrupt is not handled search all handlers
1077 for it. Intended to get systems with badly broken
1081 When an interrupt is not handled search all handlers
1082 for it. Also check all handlers each timer
1083 interrupt. Intended to get systems with badly broken
1087 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1089 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1091 <cpu number>,...,<cpu number>
1093 <cpu number>-<cpu number>
1094 (must be a positive range in ascending order)
1096 <cpu number>,...,<cpu number>-<cpu number>
1098 This option can be used to specify one or more CPUs
1099 to isolate from the general SMP balancing and scheduling
1100 algorithms. You can move a process onto or off an
1101 "isolated" CPU via the CPU affinity syscalls or cpuset.
1102 <cpu number> begins at 0 and the maximum value is
1103 "number of CPUs in system - 1".
1105 This option is the preferred way to isolate CPUs. The
1106 alternative -- manually setting the CPU mask of all
1107 tasks in the system -- can cause problems and
1108 suboptimal load balancer performance.
1112 js= [HW,JOY] Analog joystick
1113 See Documentation/input/joystick.txt.
1117 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1118 specifies the amount of memory usable by the kernel
1119 for non-movable allocations. The requested amount is
1120 spread evenly throughout all nodes in the system. The
1121 remaining memory in each node is used for Movable
1122 pages. In the event, a node is too small to have both
1123 kernelcore and Movable pages, kernelcore pages will
1124 take priority and other nodes will have a larger number
1125 of kernelcore pages. The Movable zone is used for the
1126 allocation of pages that may be reclaimed or moved
1127 by the page migration subsystem. This means that
1128 HugeTLB pages may not be allocated from this zone.
1129 Note that allocations like PTEs-from-HighMem still
1130 use the HighMem zone if it exists, and the Normal
1131 zone if it does not.
1133 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1134 Format: <Controller#>[,poll interval]
1135 The controller # is the number of the ehci usb debug
1136 port as it is probed via PCI. The poll interval is
1137 optional and is the number seconds in between
1138 each poll cycle to the debug port in case you need
1139 the functionality for interrupting the kernel with
1140 gdb or control-c on the dbgp connection. When
1141 not using this parameter you use sysrq-g to break into
1142 the kernel debugger.
1144 kgdboc= [KGDB,HW] kgdb over consoles.
1145 Requires a tty driver that supports console polling,
1146 or a supported polling keyboard driver (non-usb).
1147 Serial only format: <serial_device>[,baud]
1148 keyboard only format: kbd
1149 keyboard and serial format: kbd,<serial_device>[,baud]
1150 Optional Kernel mode setting:
1151 kms, kbd format: kms,kbd
1152 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1154 kgdbwait [KGDB] Stop kernel execution and enter the
1155 kernel debugger at the earliest opportunity.
1157 kmac= [MIPS] korina ethernet MAC address.
1158 Configure the RouterBoard 532 series on-chip
1159 Ethernet adapter MAC address.
1161 kmemleak= [KNL] Boot-time kmemleak enable/disable
1162 Valid arguments: on, off
1165 kstack=N [X86] Print N words from the kernel stack
1168 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1169 Default is 0 (don't ignore, but inject #GP)
1171 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1172 Default is 1 (enabled)
1174 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1177 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1179 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1181 kvm-intel.bypass_guest_pf=
1182 [KVM,Intel] Disables bypassing of guest page faults
1183 on Intel chips. Default is 1 (enabled)
1185 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1186 (virtualized MMU) support on capable Intel chips.
1187 Default is 1 (enabled)
1189 kvm-intel.emulate_invalid_guest_state=
1190 [KVM,Intel] Enable emulation of invalid guest states
1191 Default is 0 (disabled)
1193 kvm-intel.flexpriority=
1194 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1195 Default is 1 (enabled)
1197 kvm-intel.unrestricted_guest=
1198 [KVM,Intel] Disable unrestricted guest feature
1199 (virtualized real and unpaged mode) on capable
1200 Intel chips. Default is 1 (enabled)
1202 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1203 feature (tagged TLBs) on capable Intel chips.
1204 Default is 1 (enabled)
1210 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1213 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1216 libata.dma= [LIBATA] DMA control
1217 libata.dma=0 Disable all PATA and SATA DMA
1218 libata.dma=1 PATA and SATA Disk DMA only
1219 libata.dma=2 ATAPI (CDROM) DMA only
1220 libata.dma=4 Compact Flash DMA only
1221 Combinations also work, so libata.dma=3 enables DMA
1222 for disks and CDROMs, but not CFs.
1224 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1225 libata.ignore_hpa=0 keep BIOS limits (default)
1226 libata.ignore_hpa=1 ignore limits, using full disk
1228 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1232 libata.force= [LIBATA] Force configurations. The format is comma
1233 separated list of "[ID:]VAL" where ID is
1234 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1235 matching port, link or device. Basically, it matches
1236 the ATA ID string printed on console by libata. If
1237 the whole ID part is omitted, the last PORT and DEVICE
1238 values are used. If ID hasn't been specified yet, the
1239 configuration applies to all ports, links and devices.
1241 If only DEVICE is omitted, the parameter applies to
1242 the port and all links and devices behind it. DEVICE
1243 number of 0 either selects the first device or the
1244 first fan-out link behind PMP device. It does not
1245 select the host link. DEVICE number of 15 selects the
1246 host link and device attached to it.
1248 The VAL specifies the configuration to force. As long
1249 as there's no ambiguity shortcut notation is allowed.
1250 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1251 The following configurations can be forced.
1253 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1254 Any ID with matching PORT is used.
1256 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1258 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1259 udma[/][16,25,33,44,66,100,133] notation is also
1262 * [no]ncq: Turn on or off NCQ.
1264 * nohrst, nosrst, norst: suppress hard, soft
1267 * dump_id: dump IDENTIFY data.
1269 If there are multiple matching configurations changing
1270 the same attribute, the last one is used.
1272 memblock=debug [KNL] Enable memblock debug messages.
1274 load_ramdisk= [RAM] List of ramdisks to load from floppy
1275 See Documentation/blockdev/ramdisk.txt.
1277 lockd.nlm_grace_period=P [NFS] Assign grace period.
1280 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1283 lockd.nlm_timeout=T [NFS] Assign timeout value.
1286 lockd.nlm_udpport=M [NFS] Assign UDP port.
1289 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1292 loglevel= All Kernel Messages with a loglevel smaller than the
1293 console loglevel will be printed to the console. It can
1294 also be changed with klogd or other programs. The
1295 loglevels are defined as follows:
1297 0 (KERN_EMERG) system is unusable
1298 1 (KERN_ALERT) action must be taken immediately
1299 2 (KERN_CRIT) critical conditions
1300 3 (KERN_ERR) error conditions
1301 4 (KERN_WARNING) warning conditions
1302 5 (KERN_NOTICE) normal but significant condition
1303 6 (KERN_INFO) informational
1304 7 (KERN_DEBUG) debug-level messages
1306 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1307 Format: { n | nk | nM }
1308 n must be a power of two. The default size
1309 is set in the kernel config file.
1311 logo.nologo [FB] Disables display of the built-in Linux logo.
1312 This may be used to provide more screen space for
1313 kernel log messages and is useful when debugging
1314 kernel boot problems.
1316 lp=0 [LP] Specify parallel ports to use, e.g,
1317 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1318 lp=reset first parallel port). 'lp=0' disables the
1319 lp=auto printer driver. 'lp=reset' (which can be
1320 specified in addition to the ports) causes
1321 attached printers to be reset. Using
1322 lp=port1,port2,... specifies the parallel ports
1323 to associate lp devices with, starting with
1324 lp0. A port specification may be 'none' to skip
1325 that lp device, or a parport name such as
1326 'parport0'. Specifying 'lp=auto' instead of a
1327 port specification list means that device IDs
1328 from each port should be examined, to see if
1329 an IEEE 1284-compliant printer is attached; if
1330 so, the driver will manage that printer.
1331 See also header of drivers/char/lp.c.
1334 Sets loops_per_jiffy to given constant, thus avoiding
1335 time-consuming boot-time autodetection (up to 250 ms per
1336 CPU). 0 enables autodetection (default). To determine
1337 the correct value for your kernel, boot with normal
1338 autodetection and see what value is printed. Note that
1339 on SMP systems the preset will be applied to all CPUs,
1340 which is likely to cause problems if your CPUs need
1341 significantly divergent settings. An incorrect value
1342 will cause delays in the kernel to be wrong, leading to
1343 unpredictable I/O errors and other breakage. Although
1344 unlikely, in the extreme case this might damage your
1348 Format: <io>,<irq>,<dma>
1350 mac5380= [HW,SCSI] Format:
1351 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1353 machvec= [IA64] Force the use of a particular machine-vector
1354 (machvec) in a generic kernel.
1355 Example: machvec=hpzx1_swiotlb
1357 machtype= [Loongson] Share the same kernel image file between different
1359 Example: machtype=lemote-yeeloong-2f-7inch
1361 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1362 than or equal to this physical address is ignored.
1364 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1365 should make use of. maxcpus=n : n >= 0 limits the
1366 kernel to using 'n' processors. n=0 is a special case,
1367 it is equivalent to "nosmp", which also disables
1370 max_loop= [LOOP] Maximum number of loopback devices that can
1374 max_luns= [SCSI] Maximum number of LUNs to probe.
1375 Should be between 1 and 2^32-1.
1378 [SCSI] Maximum number of LUNs received.
1379 Should be between 1 and 16384.
1383 mce [X86-32] Machine Check Exception
1385 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1387 md= [HW] RAID subsystems devices and level
1388 See Documentation/md.txt.
1391 Format: <first>,<last>
1392 Specifies range of consoles to be captured by the MDA.
1394 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1395 Amount of memory to be used when the kernel is not able
1396 to see the whole system memory or for test.
1397 [X86-32] Use together with memmap= to avoid physical
1398 address space collisions. Without memmap= PCI devices
1399 could be placed at addresses belonging to unused RAM.
1401 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1405 [KNL,SH] Allow user to override the default size for
1406 per-device physically contiguous DMA buffers.
1408 memmap=exactmap [KNL,X86] Enable setting of an exact
1409 E820 memory map, as specified by the user.
1410 Such memmap=exactmap lines can be constructed based on
1411 BIOS output or other requirements. See the memmap=nn@ss
1414 memmap=nn[KMG]@ss[KMG]
1415 [KNL] Force usage of a specific region of memory
1416 Region of memory to be used, from ss to ss+nn.
1418 memmap=nn[KMG]#ss[KMG]
1419 [KNL,ACPI] Mark specific memory as ACPI data.
1420 Region of memory to be used, from ss to ss+nn.
1422 memmap=nn[KMG]$ss[KMG]
1423 [KNL,ACPI] Mark specific memory as reserved.
1424 Region of memory to be used, from ss to ss+nn.
1425 Example: Exclude memory from 0x18690000-0x1869ffff
1426 memmap=64K$0x18690000
1428 memmap=0x10000$0x18690000
1430 memory_corruption_check=0/1 [X86]
1431 Some BIOSes seem to corrupt the first 64k of
1432 memory when doing things like suspend/resume.
1433 Setting this option will scan the memory
1434 looking for corruption. Enabling this will
1435 both detect corruption and prevent the kernel
1436 from using the memory being corrupted.
1437 However, its intended as a diagnostic tool; if
1438 repeatable BIOS-originated corruption always
1439 affects the same memory, you can use memmap=
1440 to prevent the kernel from using that memory.
1442 memory_corruption_check_size=size [X86]
1443 By default it checks for corruption in the low
1444 64k, making this memory unavailable for normal
1445 use. Use this parameter to scan for
1446 corruption in more or less memory.
1448 memory_corruption_check_period=seconds [X86]
1449 By default it checks for corruption every 60
1450 seconds. Use this parameter to check at some
1451 other rate. 0 disables periodic checking.
1453 memtest= [KNL,X86] Enable memtest
1455 default : 0 <disable>
1456 Specifies the number of memtest passes to be
1457 performed. Each pass selects another test
1458 pattern from a given set of patterns. Memtest
1459 fills the memory with this pattern, validates
1460 memory contents and reserves bad memory
1461 regions that are detected.
1463 meye.*= [HW] Set MotionEye Camera parameters
1464 See Documentation/video4linux/meye.txt.
1466 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1467 Multi-Function General Purpose Timers on AMD Geode
1470 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1471 the BIOS has incorrectly applied a workaround. TinyBIOS
1472 version 0.98 is known to be affected, 0.99 fixes the
1473 problem by letting the user disable the workaround.
1477 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1478 physical address is ignored.
1480 mini2440= [ARM,HW,KNL]
1481 Format:[0..2][b][c][t]
1483 MINI2440 configuration specification:
1484 0 - The attached screen is the 3.5" TFT
1485 1 - The attached screen is the 7" TFT
1486 2 - The VGA Shield is attached (1024x768)
1487 Leaving out the screen size parameter will not load
1488 the TFT driver, and the framebuffer will be left
1490 b - Enable backlight. The TFT backlight pin will be
1491 linked to the kernel VESA blanking code and a GPIO
1492 LED. This parameter is not necessary when using the
1494 c - Enable the s3c camera interface.
1495 t - Reserved for enabling touchscreen support. The
1496 touchscreen support is not enabled in the mainstream
1497 kernel as of 2.6.30, a preliminary port can be found
1498 in the "bleeding edge" mini2440 support kernel at
1499 http://repo.or.cz/w/linux-2.6/mini2440.git
1502 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1503 parameter allows control of the logging verbosity for
1504 the additional memory initialisation checks. A value
1505 of 0 disables mminit logging and a level of 4 will
1506 log everything. Information is printed at KERN_DEBUG
1507 so loglevel=8 may also need to be specified.
1510 [MOUSE] Maximum time between finger touching and
1511 leaving touchpad surface for touch to be considered
1512 a tap and be reported as a left button click (for
1513 touchpads working in absolute mode only).
1515 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1516 reporting absolute coordinates, such as tablets
1517 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1518 reporting absolute coordinates, such as tablets
1520 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1521 is similar to kernelcore except it specifies the
1522 amount of memory used for migratable allocations.
1523 If both kernelcore and movablecore is specified,
1524 then kernelcore will be at *least* the specified
1525 value but may be more. If movablecore on its own
1526 is specified, the administrator must be careful
1527 that the amount of memory usable for all allocations
1533 MTD_Partition= [MTD]
1534 Format: <name>,<region-number>,<size>,<offset>
1536 MTD_Region= [MTD] Format:
1537 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1540 See drivers/mtd/cmdlinepart.c.
1542 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1544 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1546 boundary - index of last SLC block on Flex-OneNAND.
1547 The remaining blocks are configured as MLC blocks.
1548 lock - Configure if Flex-OneNAND boundary should be locked.
1549 Once locked, the boundary cannot be changed.
1550 1 indicates lock status, 0 indicates unlock status.
1553 ARM/S3C2412 JIVE boot control
1555 See arch/arm/mach-s3c2412/mach-jive.c
1557 mtouchusb.raw_coordinates=
1558 [HW] Make the MicroTouch USB driver use raw coordinates
1559 ('y', default) or cooked coordinates ('n')
1561 mtrr_chunk_size=nn[KMG] [X86]
1562 used for mtrr cleanup. It is largest continuous chunk
1563 that could hold holes aka. UC entries.
1565 mtrr_gran_size=nn[KMG] [X86]
1566 Used for mtrr cleanup. It is granularity of mtrr block.
1568 Large value could prevent small alignment from
1571 mtrr_spare_reg_nr=n [X86]
1573 Range: 0,7 : spare reg number
1575 Used for mtrr cleanup. It is spare mtrr entries number.
1576 Set to 2 or more if your graphical card needs more.
1578 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1581 See header of drivers/scsi/NCR_D700.c.
1585 ncr53c400= [HW,SCSI]
1587 ncr53c400a= [HW,SCSI]
1589 ncr53c406a= [HW,SCSI]
1591 ncr53c8xx= [HW,SCSI]
1593 netdev= [NET] Network devices parameters
1594 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1595 Note that mem_start is often overloaded to mean
1596 something different and driver-specific.
1597 This usage is only documented in each driver source
1601 [NETFILTER] Enable connection tracking flow accounting
1602 0 to disable accounting
1603 1 to enable accounting
1607 See Documentation/filesystems/nfs/nfsroot.txt.
1609 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1610 See Documentation/filesystems/nfs/nfsroot.txt.
1612 nfs.callback_tcpport=
1613 [NFS] set the TCP port on which the NFSv4 callback
1614 channel should listen.
1617 [NFS] sets the pathname to the program which is used
1618 to update the NFS client cache entries.
1620 nfs.cache_getent_timeout=
1621 [NFS] sets the timeout after which an attempt to
1622 update a cache entry is deemed to have failed.
1624 nfs.idmap_cache_timeout=
1625 [NFS] set the maximum lifetime for idmapper cache
1629 [NFS] enable 64-bit inode numbers.
1630 If zero, the NFS client will fake up a 32-bit inode
1631 number for the readdir() and stat() syscalls instead
1632 of returning the full 64-bit number.
1633 The default is to return 64-bit inode numbers.
1635 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1636 when a NMI is triggered.
1637 Format: [state][,regs][,debounce][,die]
1639 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1640 Format: [panic,][num]
1642 0 - turn nmi_watchdog off
1643 1 - use the IO-APIC timer for the NMI watchdog
1644 2 - use the local APIC for the NMI watchdog using
1645 a performance counter. Note: This will use one
1646 performance counter and the local APIC's performance
1648 When panic is specified, panic when an NMI watchdog
1650 This is useful when you use a panic=... timeout and
1651 need the box quickly up again.
1652 Instead of 1 and 2 it is possible to use the following
1653 symbolic names: lapic and ioapic
1654 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1656 netpoll.carrier_timeout=
1657 [NET] Specifies amount of time (in seconds) that
1658 netpoll should wait for a carrier. By default netpoll
1661 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1662 emulation library even if a 387 maths coprocessor
1666 [HW] Never suspend the console
1667 Disable suspending of consoles during suspend and
1668 hibernate operations. Once disabled, debugging
1669 messages can reach various consoles while the rest
1670 of the system is being put to sleep (ie, while
1671 debugging driver suspend/resume hooks). This may
1672 not work reliably with all consoles, but is known
1673 to work with serial and VGA consoles.
1675 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1676 caches in the slab allocator. Saves per-node memory,
1677 but will impact performance.
1681 noapic [SMP,APIC] Tells the kernel to not make use of any
1682 IOAPICs that may be present in the system.
1684 nobats [PPC] Do not use BATs for mapping kernel lowmem
1685 on "Classic" PPC cores.
1689 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1691 nodelayacct [KNL] Disable per-task delay accounting
1693 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1695 nodsp [SH] Disable hardware DSP at boot time.
1697 noefi [X86] Disable EFI runtime services support.
1702 On X86-32 available only on PAE configured kernels.
1703 noexec=on: enable non-executable mappings (default)
1704 noexec=off: disable non-executable mappings
1707 This affects only 32-bit executables.
1708 noexec32=on: enable non-executable mappings (default)
1709 read doesn't imply executable mappings
1710 noexec32=off: disable non-executable mappings
1711 read implies executable mappings
1713 nofpu [SH] Disable hardware FPU at boot time.
1715 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1716 register save and restore. The kernel will only save
1717 legacy floating-point registers on task switch.
1719 noxsave [BUGS=X86] Disables x86 extended register state save
1720 and restore using xsave. The kernel will fallback to
1721 enabling legacy floating-point and sse state.
1723 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1724 wfi(ARM) instruction doesn't work correctly and not to
1725 use it. This is also useful when using JTAG debugger.
1727 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1728 instruction doesn't work correctly and not to
1731 no_file_caps Tells the kernel not to honor file capabilities. The
1732 only way then for a file to be executed with privilege
1733 is to be setuid root or executed by root.
1735 nohalt [IA-64] Tells the kernel not to use the power saving
1736 function PAL_HALT_LIGHT when idle. This increases
1737 power-consumption. On the positive side, it reduces
1738 interrupt wake-up latency, which may improve performance
1739 in certain environments such as networked servers or
1742 nohz= [KNL] Boottime enable/disable dynamic ticks
1743 Valid arguments: on, off
1746 noiotrap [SH] Disables trapped I/O port accesses.
1748 noirqdebug [X86-32] Disables the code which attempts to detect and
1749 disable unhandled interrupt sources.
1751 no_timer_check [X86,APIC] Disables the code which tests for
1752 broken timer IRQ sources.
1754 noisapnp [ISAPNP] Disables ISA PnP code.
1756 noinitrd [RAM] Tells the kernel not to load any configured
1759 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1764 nojitter [IA64] Disables jitter checking for ITC timers.
1766 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1768 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1770 noltlbs [PPC] Do not use large page/tlb entries for kernel
1771 lowmem mapping on PPC40x.
1773 nomca [IA-64] Disable machine check abort handling
1775 nomce [X86-32] Machine Check Exception
1777 nomfgpt [X86-32] Disable Multi-Function General Purpose
1778 Timer usage (for AMD Geode machines).
1780 nopat [X86] Disable PAT (page attribute table extension of
1781 pagetables) support.
1783 norandmaps Don't use address space randomization. Equivalent to
1784 echo 0 > /proc/sys/kernel/randomize_va_space
1786 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1788 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1789 with UP alternatives
1791 noresidual [PPC] Don't use residual data on PReP machines.
1793 noresume [SWSUSP] Disables resume and restores original swap
1796 no-scroll [VGA] Disables scrollback.
1797 This is required for the Braillex ib80-piezo Braille
1798 reader made by F.H. Papenmeier (Germany).
1802 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1804 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1805 and disable the IO APIC. legacy for "maxcpus=0".
1807 nosoftlockup [KNL] Disable the soft-lockup detector.
1809 noswapaccount [KNL] Disable accounting of swap in memory resource
1810 controller. (See Documentation/cgroups/memory.txt)
1812 nosync [HW,M68K] Disables sync negotiation for all devices.
1814 notsc [BUGS=X86-32] Disable Time Stamp Counter
1816 nousb [USB] Disable the USB subsystem
1818 nowatchdog [KNL] Disable the lockup detector.
1822 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1824 nptcg= [IA64] Override max number of concurrent global TLB
1825 purges which is reported from either PAL_VM_SUMMARY or
1828 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1829 could support. nr_cpus=n : n >= 1 limits the kernel to
1830 supporting 'n' processors. Later in runtime you can not
1831 use hotplug cpu feature to put more cpu back to online.
1832 just like you compile the kernel NR_CPUS=n
1834 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1836 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1837 one of ['zone', 'node', 'default'] can be specified
1838 This can be set from sysctl after boot.
1839 See Documentation/sysctl/vm.txt for details.
1841 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1842 See Documentation/debugging-via-ohci1394.txt for more
1845 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1846 Rather than timing out after 20 ms if an EC
1847 command is not properly ACKed, override the length
1848 of the timeout. We have interrupts disabled while
1849 waiting for the ACK, so if this is set too high
1850 interrupts *may* be lost!
1852 omap_mux= [OMAP] Override bootloader pin multiplexing.
1853 Format: <mux_mode0.mode_name=value>...
1854 For example, to override I2C bus2:
1855 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1860 oprofile.timer= [HW]
1861 Use timer interrupt instead of performance counters
1863 oprofile.cpu_type= Force an oprofile cpu type
1864 This might be useful if you have an older oprofile
1865 userland or if you want common events.
1866 Format: { arch_perfmon }
1867 arch_perfmon: [X86] Force use of architectural
1868 perfmon on Intel CPUs instead of the
1869 CPU specific event set.
1871 osst= [HW,SCSI] SCSI Tape Driver
1872 Format: <buffer_size>,<write_threshold>
1873 See also Documentation/scsi/st.txt.
1875 panic= [KNL] Kernel behaviour on panic
1878 parkbd.port= [HW] Parallel port number the keyboard adapter is
1879 connected to, default is 0.
1881 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1882 0 for XT, 1 for AT (default is AT).
1885 parport= [HW,PPT] Specify parallel ports. 0 disables.
1886 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1887 Use 'auto' to force the driver to use any
1888 IRQ/DMA settings detected (the default is to
1889 ignore detected IRQ/DMA settings because of
1890 possible conflicts). You can specify the base
1891 address, IRQ, and DMA settings; IRQ and DMA
1892 should be numbers, or 'auto' (for using detected
1893 settings on that particular port), or 'nofifo'
1894 (to avoid using a FIFO even if it is detected).
1895 Parallel ports are assigned in the order they
1896 are specified on the command line, starting
1899 parport_init_mode= [HW,PPT]
1900 Configure VIA parallel port to operate in
1901 a specific mode. This is necessary on Pegasos
1902 computer where firmware has no options for setting
1903 up parallel port mode and sets it to spp.
1904 Currently this function knows 686a and 8231 chips.
1905 Format: [spp|ps2|epp|ecp|ecpepp]
1907 pas2= [HW,OSS] Format:
1908 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1911 See header of drivers/scsi/pas16.c.
1914 Halt all CPUs after the first oops has been printed for
1915 the specified number of seconds. This is to be used if
1916 your oopses keep scrolling off the screen.
1921 See header of drivers/block/paride/pcd.c.
1922 See also Documentation/blockdev/paride.txt.
1924 pci=option[,option...] [PCI] various PCI subsystem options:
1925 earlydump [X86] dump PCI config space before the kernel
1927 off [X86] don't probe for the PCI bus
1928 bios [X86-32] force use of PCI BIOS, don't access
1929 the hardware directly. Use this if your machine
1930 has a non-standard PCI host bridge.
1931 nobios [X86-32] disallow use of PCI BIOS, only direct
1932 hardware access methods are allowed. Use this
1933 if you experience crashes upon bootup and you
1934 suspect they are caused by the BIOS.
1935 conf1 [X86] Force use of PCI Configuration
1937 conf2 [X86] Force use of PCI Configuration
1939 noaer [PCIE] If the PCIEAER kernel config parameter is
1940 enabled, this kernel boot option can be used to
1941 disable the use of PCIE advanced error reporting.
1942 nodomains [PCI] Disable support for multiple PCI
1943 root domains (aka PCI segments, in ACPI-speak).
1944 nommconf [X86] Disable use of MMCONFIG for PCI
1946 check_enable_amd_mmconf [X86] check for and enable
1947 properly configured MMIO access to PCI
1948 config space on AMD family 10h CPU
1949 nomsi [MSI] If the PCI_MSI kernel config parameter is
1950 enabled, this kernel boot option can be used to
1951 disable the use of MSI interrupts system-wide.
1952 noioapicquirk [APIC] Disable all boot interrupt quirks.
1953 Safety option to keep boot IRQs enabled. This
1954 should never be necessary.
1955 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1956 primary IO-APIC for bridges that cannot disable
1957 boot IRQs. This fixes a source of spurious IRQs
1958 when the system masks IRQs.
1959 noioapicreroute [APIC] Disable workaround that uses the
1960 boot IRQ equivalent of an IRQ that connects to
1961 a chipset where boot IRQs cannot be disabled.
1962 The opposite of ioapicreroute.
1963 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1964 routing table. These calls are known to be buggy
1965 on several machines and they hang the machine
1966 when used, but on other computers it's the only
1967 way to get the interrupt routing table. Try
1968 this option if the kernel is unable to allocate
1969 IRQs or discover secondary PCI buses on your
1971 rom [X86] Assign address space to expansion ROMs.
1972 Use with caution as certain devices share
1973 address decoders between ROMs and other
1975 norom [X86] Do not assign address space to
1976 expansion ROMs that do not already have
1977 BIOS assigned address ranges.
1978 nobar [X86] Do not assign address space to the
1979 BARs that weren't assigned by the BIOS.
1980 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1981 assigned automatically to PCI devices. You can
1982 make the kernel exclude IRQs of your ISA cards
1984 pirqaddr=0xAAAAA [X86] Specify the physical address
1985 of the PIRQ table (normally generated
1986 by the BIOS) if it is outside the
1987 F0000h-100000h range.
1988 lastbus=N [X86] Scan all buses thru bus #N. Can be
1989 useful if the kernel is unable to find your
1990 secondary buses and you want to tell it
1991 explicitly which ones they are.
1992 assign-busses [X86] Always assign all PCI bus
1993 numbers ourselves, overriding
1994 whatever the firmware may have done.
1995 usepirqmask [X86] Honor the possible IRQ mask stored
1996 in the BIOS $PIR table. This is needed on
1997 some systems with broken BIOSes, notably
1998 some HP Pavilion N5400 and Omnibook XE3
1999 notebooks. This will have no effect if ACPI
2000 IRQ routing is enabled.
2001 noacpi [X86] Do not use ACPI for IRQ routing
2002 or for PCI scanning.
2003 use_crs [X86] Use PCI host bridge window information
2004 from ACPI. On BIOSes from 2008 or later, this
2005 is enabled by default. If you need to use this,
2006 please report a bug.
2007 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2008 If you need to use this, please report a bug.
2009 routeirq Do IRQ routing for all PCI devices.
2010 This is normally done in pci_enable_device(),
2011 so this option is a temporary workaround
2012 for broken drivers that don't call it.
2013 skip_isa_align [X86] do not align io start addr, so can
2014 handle more pci cards
2015 firmware [ARM] Do not re-enumerate the bus but instead
2016 just use the configuration from the
2017 bootloader. This is currently used on
2018 IXP2000 systems where the bus has to be
2019 configured a certain way for adjunct CPUs.
2020 noearly [X86] Don't do any early type 1 scanning.
2021 This might help on some broken boards which
2022 machine check when some devices' config space
2023 is read. But various workarounds are disabled
2024 and some IOMMU drivers will not work.
2025 bfsort Sort PCI devices into breadth-first order.
2026 This sorting is done to get a device
2027 order compatible with older (<= 2.4) kernels.
2028 nobfsort Don't sort PCI devices into breadth-first order.
2029 cbiosize=nn[KMG] The fixed amount of bus space which is
2030 reserved for the CardBus bridge's IO window.
2031 The default value is 256 bytes.
2032 cbmemsize=nn[KMG] The fixed amount of bus space which is
2033 reserved for the CardBus bridge's memory
2034 window. The default value is 64 megabytes.
2037 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2038 Specifies alignment and device to reassign
2039 aligned memory resources.
2040 If <order of align> is not specified,
2041 PAGE_SIZE is used as alignment.
2042 PCI-PCI bridge can be specified, if resource
2043 windows need to be expanded.
2044 ecrc= Enable/disable PCIe ECRC (transaction layer
2045 end-to-end CRC checking).
2046 bios: Use BIOS/firmware settings. This is the
2051 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2054 force Enable ASPM even on devices that claim not to support it.
2055 WARNING: Forcing ASPM on may cause system lockups.
2057 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2058 Format: {auto|force}[,nomsi]
2059 auto Use native PCIe PME signaling if the BIOS allows the
2060 kernel to control PCIe config registers of root ports.
2061 force Use native PCIe PME signaling even if the BIOS refuses
2062 to allow the kernel to control the relevant PCIe config
2064 nomsi Do not use MSI for native PCIe PME signaling (this makes
2065 all PCIe root ports use INTx for everything).
2067 pcmv= [HW,PCMCIA] BadgePAD 4
2070 See Documentation/blockdev/paride.txt.
2072 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2075 See arch/parisc/kernel/pdc_chassis.c
2077 percpu_alloc= Select which percpu first chunk allocator to use.
2078 Currently supported values are "embed" and "page".
2079 Archs may support subset or none of the selections.
2080 See comments in mm/percpu.c for details on each
2081 allocator. This parameter is primarily for debugging
2082 and performance comparison.
2085 See Documentation/blockdev/paride.txt.
2088 See Documentation/blockdev/paride.txt.
2090 pirq= [SMP,APIC] Manual mp-table setup
2091 See Documentation/x86/i386/IO-APIC.txt.
2093 plip= [PPT,NET] Parallel port network link
2094 Format: { parport<nr> | timid | 0 }
2095 See also Documentation/parport.txt.
2097 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2098 Override pmtimer IOPort with a hex value.
2102 Enable PNP debug messages. This depends on the
2103 CONFIG_PNP_DEBUG_MESSAGES option.
2109 { on | off | curr | res | no-curr | no-res }
2112 [ISAPNP] Exclude IRQs for the autoconfiguration
2115 [ISAPNP] Exclude DMAs for the autoconfiguration
2117 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2118 Ranges are in pairs (I/O port base and size).
2121 [ISAPNP] Exclude memory regions for the
2123 Ranges are in pairs (memory base and size).
2125 ports= [IP_VS_FTP] IPVS ftp helper module
2127 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2129 Format: <port>,<port>....
2131 print-fatal-signals=
2132 [KNL] debug: print fatal signals
2134 If enabled, warn about various signal handling
2135 related application anomalies: too many signals,
2136 too many POSIX.1 timers, fatal signals causing a
2139 If you hit the warning due to signal overflow,
2140 you might want to try "ulimit -i unlimited".
2144 printk.time= Show timing data prefixed to each printk message line
2145 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2147 processor.max_cstate= [HW,ACPI]
2148 Limit processor to maximum C-state
2149 max_cstate=9 overrides any DMI blacklist limit.
2151 processor.nocst [HW,ACPI]
2152 Ignore the _CST method to determine C-states,
2153 instead using the legacy FADT method
2155 profile= [KNL] Enable kernel profiling via /proc/profile
2156 Format: [schedule,]<number>
2157 Param: "schedule" - profile schedule points.
2158 Param: <number> - step/bucket size as a power of 2 for
2159 statistical time based profiling.
2160 Param: "sleep" - profile D-state sleeping (millisecs).
2161 Requires CONFIG_SCHEDSTATS
2162 Param: "kvm" - profile VM exits.
2164 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2166 See Documentation/blockdev/ramdisk.txt.
2168 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2169 probe for; one of (bare|imps|exps|lifebook|any).
2170 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2172 psmouse.resetafter= [HW,MOUSE]
2173 Try to reset the device after so many bad packets
2176 [HW,MOUSE] Set desired mouse resolution, in dpi.
2177 psmouse.smartscroll=
2178 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2179 0 = disabled, 1 = enabled (default).
2181 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2183 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2186 See Documentation/blockdev/paride.txt.
2189 [KNL] Number of legacy pty's. Overwrites compiled-in
2192 quiet [KNL] Disable most log messages
2197 See Documentation/md.txt.
2199 ramdisk_blocksize= [RAM]
2200 See Documentation/blockdev/ramdisk.txt.
2202 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2203 See Documentation/blockdev/ramdisk.txt.
2205 rcupdate.blimit= [KNL,BOOT]
2206 Set maximum number of finished RCU callbacks to process
2209 rcupdate.qhimark= [KNL,BOOT]
2210 Set threshold of queued
2211 RCU callbacks over which batch limiting is disabled.
2213 rcupdate.qlowmark= [KNL,BOOT]
2214 Set threshold of queued RCU callbacks below which
2215 batch limiting is re-enabled.
2219 Run specified binary instead of /init from the ramdisk,
2220 used for early userspace startup. See initrd.
2222 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2223 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2224 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2227 [KNL, SMP] Set scheduler's default relax_domain_level.
2228 See Documentation/cgroups/cpusets.txt.
2230 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2232 reservetop= [X86-32]
2234 Reserves a hole at the top of the kernel virtual
2237 reset_devices [KNL] Force drivers to reset the underlying device
2238 during initialization.
2241 Specify the partition device for software suspend
2243 resume_offset= [SWSUSP]
2244 Specify the offset from the beginning of the partition
2245 given by "resume=" at which the swap header is located,
2246 in <PAGE_SIZE> units (needed only for swap files).
2247 See Documentation/power/swsusp-and-swap-files.txt
2249 retain_initrd [RAM] Keep initrd memory after extraction
2251 rhash_entries= [KNL,NET]
2252 Set number of hash buckets for route cache
2254 riscom8= [HW,SERIAL]
2255 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2257 ro [KNL] Mount root device read-only on boot
2259 root= [KNL] Root filesystem
2261 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2262 mount the root filesystem
2264 rootflags= [KNL] Set root filesystem mount option string
2266 rootfstype= [KNL] Set root filesystem type
2268 rootwait [KNL] Wait (indefinitely) for root device to show up.
2269 Useful for devices that are detected asynchronously
2270 (e.g. USB and MMC devices).
2272 rw [KNL] Mount root device read-write on boot
2274 S [KNL] Run init in single mode
2277 See drivers/net/irda/sa1100_ir.c.
2279 sbni= [NET] Granch SBNI12 leased line adapter
2281 sched_debug [KNL] Enables verbose scheduler debug messages.
2283 scsi_debug_*= [SCSI]
2284 See drivers/scsi/scsi_debug.c.
2286 scsi_default_dev_flags=
2287 [SCSI] SCSI default device flags
2290 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2291 Format: <vendor>:<model>:<flags>
2292 (flags are integer value)
2294 scsi_logging_level= [SCSI] a bit mask of logging levels
2295 See drivers/scsi/scsi_logging.h for bits. Also
2296 settable via sysctl at dev.scsi.logging_level
2297 (/proc/sys/dev/scsi/logging_level).
2298 There is also a nice 'scsi_logging_level' script in the
2299 S390-tools package, available for download at
2300 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2302 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2303 discovered. async scans them in kernel threads,
2304 allowing boot to proceed. none ignores them, expecting
2305 user space to do the scan.
2307 security= [SECURITY] Choose a security module to enable at boot.
2308 If this boot parameter is not specified, only the first
2309 security module asking for security registration will be
2310 loaded. An invalid security module name will be treated
2311 as if no module has been chosen.
2313 selinux= [SELINUX] Disable or enable SELinux at boot time.
2314 Format: { "0" | "1" }
2315 See security/selinux/Kconfig help text.
2318 Default value is set via kernel config option.
2319 If enabled at boot time, /selinux/disable can be used
2320 later to disable prior to initial policy load.
2322 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2323 Format: { "0" | "1" }
2324 See security/apparmor/Kconfig help text
2327 Default value is set via kernel config option.
2329 serialnumber [BUGS=X86-32]
2332 Maximal number of shapers.
2334 show_msr= [x86] show boot-time MSR settings
2335 Format: { <integer> }
2336 Show boot-time (BIOS-initialized) MSR settings.
2337 The parameter means the number of CPUs to show,
2338 for example 1 means boot CPU only.
2341 See header of drivers/scsi/sim710.c.
2348 slub_debug[=options[,slabs]] [MM, SLUB]
2349 Enabling slub_debug allows one to determine the
2350 culprit if slab objects become corrupted. Enabling
2351 slub_debug can create guard zones around objects and
2352 may poison objects when not in use. Also tracks the
2353 last alloc / free. For more information see
2354 Documentation/vm/slub.txt.
2356 slub_max_order= [MM, SLUB]
2357 Determines the maximum allowed order for slabs.
2358 A high setting may cause OOMs due to memory
2359 fragmentation. For more information see
2360 Documentation/vm/slub.txt.
2362 slub_min_objects= [MM, SLUB]
2363 The minimum number of objects per slab. SLUB will
2364 increase the slab order up to slub_max_order to
2365 generate a sufficiently large slab able to contain
2366 the number of objects indicated. The higher the number
2367 of objects the smaller the overhead of tracking slabs
2368 and the less frequently locks need to be acquired.
2369 For more information see Documentation/vm/slub.txt.
2371 slub_min_order= [MM, SLUB]
2372 Determines the mininum page order for slabs. Must be
2373 lower than slub_max_order.
2374 For more information see Documentation/vm/slub.txt.
2376 slub_nomerge [MM, SLUB]
2377 Disable merging of slabs with similar size. May be
2378 necessary if there is some reason to distinguish
2379 allocs to different slabs. Debug options disable
2380 merging on their own.
2381 For more information see Documentation/vm/slub.txt.
2384 Format: <io1>[,<io2>[,...,<io8>]]
2386 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2387 attempt to substitute SMP alternatives once at boot.
2389 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2390 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2391 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2392 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2393 smsc-ircc2.ircc_irq= [HW] IRQ line
2394 smsc-ircc2.ircc_dma= [HW] DMA channel
2395 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2396 0: Toshiba Satellite 1800 (GP data pin select)
2397 1: Fast pin select (default)
2400 snd-ad1816a= [HW,ALSA]
2402 snd-ad1848= [HW,ALSA]
2404 snd-ali5451= [HW,ALSA]
2406 snd-als100= [HW,ALSA]
2408 snd-als4000= [HW,ALSA]
2410 snd-azt2320= [HW,ALSA]
2412 snd-cmi8330= [HW,ALSA]
2414 snd-cmipci= [HW,ALSA]
2416 snd-cs4231= [HW,ALSA]
2418 snd-cs4232= [HW,ALSA]
2420 snd-cs4236= [HW,ALSA]
2422 snd-cs4281= [HW,ALSA]
2424 snd-cs46xx= [HW,ALSA]
2426 snd-dt019x= [HW,ALSA]
2428 snd-dummy= [HW,ALSA]
2430 snd-emu10k1= [HW,ALSA]
2432 snd-ens1370= [HW,ALSA]
2434 snd-ens1371= [HW,ALSA]
2436 snd-es968= [HW,ALSA]
2438 snd-es1688= [HW,ALSA]
2440 snd-es18xx= [HW,ALSA]
2442 snd-es1938= [HW,ALSA]
2444 snd-es1968= [HW,ALSA]
2446 snd-fm801= [HW,ALSA]
2448 snd-gusclassic= [HW,ALSA]
2450 snd-gusextreme= [HW,ALSA]
2452 snd-gusmax= [HW,ALSA]
2456 snd-ice1712= [HW,ALSA]
2458 snd-intel8x0= [HW,ALSA]
2460 snd-interwave= [HW,ALSA]
2465 snd-korg1212= [HW,ALSA]
2467 snd-maestro3= [HW,ALSA]
2469 snd-mpu401= [HW,ALSA]
2471 snd-mtpav= [HW,ALSA]
2473 snd-nm256= [HW,ALSA]
2475 snd-opl3sa2= [HW,ALSA]
2483 snd-opti93x= [HW,ALSA]
2487 snd-rme32= [HW,ALSA]
2489 snd-rme96= [HW,ALSA]
2491 snd-rme9652= [HW,ALSA]
2497 snd-sbawe= [HW,ALSA]
2499 snd-serial= [HW,ALSA]
2501 snd-sgalaxy= [HW,ALSA]
2503 snd-sonicvibes= [HW,ALSA]
2508 snd-sun-cs4231= [HW,ALSA]
2510 snd-trident= [HW,ALSA]
2512 snd-usb-audio= [HW,ALSA,USB]
2514 snd-via82xx= [HW,ALSA]
2516 snd-virmidi= [HW,ALSA]
2518 snd-wavefront= [HW,ALSA]
2520 snd-ymfpci= [HW,ALSA]
2523 [KNL] Should the soft-lockup detector generate panics.
2525 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2526 See Documentation/sonypi.txt
2528 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2529 See Documentation/serial/specialix.txt.
2531 spia_io_base= [HW,MTD]
2537 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2539 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2540 See Documentation/scsi/st.txt.
2543 Enabled the stack tracer on boot up.
2547 Set the STI (builtin display/keyboard on the HP-PARISC
2548 machines) console (graphic card) which should be used
2549 as the initial boot-console.
2550 See also comment in drivers/video/console/sticore.c.
2553 See comment in drivers/video/console/sticore.c.
2556 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2558 sunrpc.min_resvport=
2559 sunrpc.max_resvport=
2561 SunRPC servers often require that client requests
2562 originate from a privileged port (i.e. a port in the
2563 range 0 < portnr < 1024).
2564 An administrator who wishes to reserve some of these
2565 ports for other uses may adjust the range that the
2566 kernel's sunrpc client considers to be privileged
2567 using these two parameters to set the minimum and
2568 maximum port values.
2572 Control how the NFS server code allocates CPUs to
2573 service thread pools. Depending on how many NICs
2574 you have and where their interrupts are bound, this
2575 option will affect which CPUs will do NFS serving.
2576 Note: this parameter cannot be changed while the
2577 NFS server is running.
2579 auto the server chooses an appropriate mode
2580 automatically using heuristics
2581 global a single global pool contains all CPUs
2582 percpu one pool for each CPU
2583 pernode one pool for each NUMA node (equivalent
2584 to global on non-NUMA machines)
2586 sunrpc.tcp_slot_table_entries=
2587 sunrpc.udp_slot_table_entries=
2589 Sets the upper limit on the number of simultaneous
2590 RPC calls that can be sent from the client to a
2591 server. Increasing these values may allow you to
2592 improve throughput, but will also increase the
2593 amount of memory reserved for use by the client.
2595 swiotlb= [IA-64] Number of I/O TLB slabs
2599 sym53c416= [HW,SCSI]
2600 See header of drivers/scsi/sym53c416.c.
2602 sysrq_always_enabled
2604 Ignore sysrq setting - this boot parameter will
2605 neutralize any effect of /proc/sys/kernel/sysrq.
2606 Useful for debugging.
2609 See header of drivers/scsi/t128.c.
2613 test_suspend= [SUSPEND]
2614 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2615 standby suspend) as the system sleep state to briefly
2616 enter during system startup. The system is woken from
2617 this state using a wakeup-capable RTC alarm.
2619 thash_entries= [KNL,NET]
2620 Set number of hash buckets for TCP connection
2622 thermal.act= [HW,ACPI]
2623 -1: disable all active trip points in all thermal zones
2624 <degrees C>: override all lowest active trip points
2626 thermal.crt= [HW,ACPI]
2627 -1: disable all critical trip points in all thermal zones
2628 <degrees C>: override all critical trip points
2630 thermal.nocrt= [HW,ACPI]
2631 Set to disable actions on ACPI thermal zone
2632 critical and hot trip points.
2634 thermal.off= [HW,ACPI]
2635 1: disable ACPI thermal control
2637 thermal.psv= [HW,ACPI]
2638 -1: disable all passive trip points
2639 <degrees C>: override all passive trip points to this
2642 thermal.tzp= [HW,ACPI]
2643 Specify global default ACPI thermal zone polling rate
2644 <deci-seconds>: poll all this frequency
2645 0: no polling (default)
2648 See comment before function dc390_setup() in
2649 drivers/scsi/tmscsim.c.
2653 Specify if the kernel should make use of the cpu
2654 topology informations if the hardware supports these.
2655 The scheduler will make use of these informations and
2656 e.g. base its process migration decisions on it.
2661 tpm_suspend_pcr=[HW,TPM]
2662 Format: integer pcr id
2663 Specify that at suspend time, the tpm driver
2664 should extend the specified pcr with zeros,
2665 as a workaround for some chips which fail to
2666 flush the last written pcr on TPM_SaveState.
2667 This will guarantee that all the other pcrs
2670 trace_buf_size=nn[KMG]
2671 [FTRACE] will set tracing buffer size.
2673 trace_event=[event-list]
2674 [FTRACE] Set and start specified trace events in order
2675 to facilitate early boot debugging.
2676 See also Documentation/trace/events.txt
2678 trix= [HW,OSS] MediaTrix AudioTrix Pro
2680 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2682 tsc= Disable clocksource-must-verify flag for TSC.
2684 [x86] reliable: mark tsc clocksource as reliable, this
2685 disables clocksource verification at runtime.
2686 Used to enable high-resolution timer mode on older
2687 hardware, and in virtualized environment.
2689 turbografx.map[2|3]= [HW,JOY]
2690 TurboGraFX parallel port interface
2692 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2693 See also Documentation/input/joystick-parport.txt
2695 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2696 See header of drivers/scsi/u14-34f.c.
2704 uhash_entries= [KNL,NET]
2705 Set number of hash buckets for UDP/UDP-Lite connections
2708 [USB] Ignore overcurrent events (default N).
2709 Some badly-designed motherboards generate lots of
2710 bogus events, for ports that aren't wired to
2711 anything. Set this parameter to avoid log spamming.
2712 Note that genuine overcurrent events won't be
2717 Set unknown_nmi_panic=1 early on boot.
2719 usbcore.autosuspend=
2720 [USB] The autosuspend time delay (in seconds) used
2721 for newly-detected USB devices (default 2). This
2722 is the time required before an idle device will be
2723 autosuspended. Devices for which the delay is set
2724 to a negative value won't be autosuspended at all.
2726 usbcore.usbfs_snoop=
2727 [USB] Set to log all usbfs traffic (default 0 = off).
2729 usbcore.blinkenlights=
2730 [USB] Set to cycle leds on hubs (default 0 = off).
2732 usbcore.old_scheme_first=
2733 [USB] Start with the old device initialization
2734 scheme (default 0 = off).
2736 usbcore.use_both_schemes=
2737 [USB] Try the other device initialization scheme
2738 if the first one fails (default 1 = enabled).
2740 usbcore.initial_descriptor_timeout=
2741 [USB] Specifies timeout for the initial 64-byte
2742 USB_REQ_GET_DESCRIPTOR request in milliseconds
2743 (default 5000 = 5.0 seconds).
2746 [USBHID] The interval which mice are to be polled at.
2748 usb-storage.delay_use=
2749 [UMS] The delay in seconds before a new device is
2750 scanned for Logical Units (default 5).
2753 [UMS] A list of quirks entries to supplement or
2754 override the built-in unusual_devs list. List
2755 entries are separated by commas. Each entry has
2756 the form VID:PID:Flags where VID and PID are Vendor
2757 and Product ID values (4-digit hex numbers) and
2758 Flags is a set of characters, each corresponding
2759 to a common usb-storage quirk flag as follows:
2760 a = SANE_SENSE (collect more than 18 bytes
2762 b = BAD_SENSE (don't collect more than 18
2763 bytes of sense data);
2764 c = FIX_CAPACITY (decrease the reported
2765 device capacity by one sector);
2766 h = CAPACITY_HEURISTICS (decrease the
2767 reported device capacity by one
2768 sector if the number is odd);
2769 i = IGNORE_DEVICE (don't bind to this
2771 l = NOT_LOCKABLE (don't try to lock and
2772 unlock ejectable media);
2773 m = MAX_SECTORS_64 (don't transfer more
2774 than 64 sectors = 32 KB at a time);
2775 o = CAPACITY_OK (accept the capacity
2776 reported by the device);
2777 r = IGNORE_RESIDUE (the device reports
2778 bogus residue values);
2779 s = SINGLE_LUN (the device has only one
2781 w = NO_WP_DETECT (don't test whether the
2782 medium is write-protected).
2783 Example: quirks=0419:aaf5:rl,0421:0433:rc
2786 [X86] Flags controlling user PTE allocations.
2788 nohigh = do not allocate PTE pages in
2789 HIGHMEM regardless of setting
2793 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2794 vdso=1: enable VDSO (default)
2795 vdso=0: disable VDSO mapping
2798 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2799 vdso32=1: enable 32-bit VDSO (default)
2800 vdso32=0: disable 32-bit VDSO mapping
2803 vector=percpu: enable percpu vector domain
2805 video= [FB] Frame buffer configuration
2806 See Documentation/fb/modedb.txt.
2808 vga= [BOOT,X86-32] Select a particular video mode
2809 See Documentation/x86/boot.txt and
2810 Documentation/svga.txt.
2811 Use vga=ask for menu.
2812 This is actually a boot loader parameter; the value is
2813 passed to the kernel using a special protocol.
2815 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2816 size of <nn>. This can be used to increase the
2817 minimum size (128MB on x86). It can also be used to
2818 decrease the size and leave more room for directly
2821 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2824 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2827 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2830 vt.cur_default= [VT] Default cursor shape.
2831 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2832 the parameters of the <Esc>[?A;B;Cc escape sequence;
2833 see VGA-softcursor.txt. Default: 2 = underline.
2835 vt.default_blu= [VT]
2836 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2837 Change the default blue palette of the console.
2838 This is a 16-member array composed of values
2841 vt.default_grn= [VT]
2842 Format: <green0>,<green1>,<green2>,...,<green15>
2843 Change the default green palette of the console.
2844 This is a 16-member array composed of values
2847 vt.default_red= [VT]
2848 Format: <red0>,<red1>,<red2>,...,<red15>
2849 Change the default red palette of the console.
2850 This is a 16-member array composed of values
2856 Set system-wide default UTF-8 mode for all tty's.
2857 Default is 1, i.e. UTF-8 mode is enabled for all
2858 newly opened terminals.
2860 vt.global_cursor_default=
2863 Set system-wide default for whether a cursor
2864 is shown on new VTs. Default is -1,
2865 i.e. cursors will be created by default unless
2866 overridden by individual drivers. 0 will hide
2867 cursors, 1 will display them.
2869 waveartist= [HW,OSS]
2870 Format: <io>,<irq>,<dma>,<dma2>
2873 See header of drivers/scsi/wd33c93.c.
2876 See header of drivers/scsi/wd7000.c.
2878 watchdog timers [HW,WDT] For information on watchdog timers,
2879 see Documentation/watchdog/watchdog-parameters.txt
2880 or other driver-specific files in the
2881 Documentation/watchdog/ directory.
2883 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2884 default x2apic cluster mode on platforms
2887 x86_mrst_timer= [X86-32,APBT]
2888 Choose timer option for x86 Moorestown MID platform.
2889 Two valid options are apbt timer only and lapic timer
2890 plus one apbt timer for broadcast timer.
2891 x86_mrst_timer=apbt_only | lapic_and_apbt
2893 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2894 xd_geo= See header of drivers/block/xd.c.
2896 xen_emul_unplug= [HW,X86,XEN]
2897 Unplug Xen emulated devices
2898 Format: [unplug0,][unplug1]
2899 ide-disks -- unplug primary master IDE devices
2900 aux-ide-disks -- unplug non-primary-master IDE devices
2901 nics -- unplug network devices
2902 all -- unplug all emulated devices (NICs and IDE disks)
2903 ignore -- continue loading the Xen platform PCI driver even
2904 if the version check failed
2906 xirc2ps_cs= [NET,PCMCIA]
2908 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2910 ______________________________________________________________________
2914 Add documentation for ALSA options.
2915 Add more DRM drivers.