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 ARM ARM architecture is enabled.
44 AVR32 AVR32 architecture is enabled.
45 AX25 Appropriate AX.25 support is enabled.
46 BLACKFIN Blackfin architecture is enabled.
47 DRM Direct Rendering Management support is enabled.
48 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
49 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
50 EFI EFI Partitioning (GPT) is enabled
51 EIDE EIDE/ATAPI support is enabled.
52 EVM Extended Verification Module
53 FB The frame buffer device is enabled.
54 FTRACE Function tracing enabled.
55 GCOV GCOV profiling is enabled.
56 HW Appropriate hardware is enabled.
57 IA-64 IA-64 architecture is enabled.
58 IMA Integrity measurement architecture is enabled.
59 IOSCHED More than one I/O scheduler is enabled.
60 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
61 IPV6 IPv6 support is enabled.
62 ISAPNP ISA PnP code is enabled.
63 ISDN Appropriate ISDN support is enabled.
64 JOY Appropriate joystick support is enabled.
65 KGDB Kernel debugger support is enabled.
66 KVM Kernel Virtual Machine support is enabled.
67 LIBATA Libata driver is enabled
68 LP Printer support is enabled.
69 LOOP Loopback device support is enabled.
70 M68k M68k architecture is enabled.
71 These options have more detailed description inside of
72 Documentation/m68k/kernel-options.txt.
73 MCA MCA bus support is enabled.
74 MDA MDA console support is enabled.
75 MIPS MIPS architecture is enabled.
76 MOUSE Appropriate mouse support is enabled.
77 MSI Message Signaled Interrupts (PCI).
78 MTD MTD (Memory Technology Device) support is enabled.
79 NET Appropriate network support is enabled.
80 NUMA NUMA support is enabled.
81 NFS Appropriate NFS support is enabled.
82 OSS OSS sound support is enabled.
83 PV_OPS A paravirtualized kernel is enabled.
84 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
85 PARISC The PA-RISC architecture is enabled.
86 PCI PCI bus support is enabled.
87 PCIE PCI Express support is enabled.
88 PCMCIA The PCMCIA subsystem is enabled.
89 PNP Plug & Play support is enabled.
90 PPC PowerPC architecture is enabled.
91 PPT Parallel port support is enabled.
92 PS2 Appropriate PS/2 support is enabled.
93 RAM RAM disk support is enabled.
94 S390 S390 architecture is enabled.
95 SCSI Appropriate SCSI support is enabled.
96 A lot of drivers have their options described inside
97 the Documentation/scsi/ sub-directory.
98 SECURITY Different security models are enabled.
99 SELINUX SELinux support is enabled.
100 APPARMOR AppArmor support is enabled.
101 SERIAL Serial support is enabled.
102 SH SuperH architecture is enabled.
103 SMP The kernel is an SMP kernel.
104 SPARC Sparc architecture is enabled.
105 SWSUSP Software suspend (hibernation) is enabled.
106 SUSPEND System suspend states are enabled.
107 TPM TPM drivers are enabled.
108 TS Appropriate touchscreen support is enabled.
109 UMS USB Mass Storage support is enabled.
110 USB USB support is enabled.
111 USBHID USB Human Interface Device support is enabled.
112 V4L Video For Linux support is enabled.
113 VGA The VGA console has been enabled.
114 VT Virtual terminal support is enabled.
115 WDT Watchdog support is enabled.
116 XT IBM PC/XT MFM hard disk support is enabled.
117 X86-32 X86-32, aka i386 architecture is enabled.
118 X86-64 X86-64 architecture is enabled.
119 More X86-64 boot options can be found in
120 Documentation/x86/x86_64/boot-options.txt .
121 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
122 XEN Xen support is enabled
124 In addition, the following text indicates that the option:
126 BUGS= Relates to possible processor bugs on the said processor.
127 KNL Is a kernel start-up parameter.
128 BOOT Is a boot loader parameter.
130 Parameters denoted with BOOT are actually interpreted by the boot
131 loader, and have no meaning to the kernel directly.
132 Do not modify the syntax of boot loader parameters without extreme
133 need or coordination with <Documentation/x86/boot.txt>.
135 There are also arch-specific kernel-parameters not documented here.
136 See for example <Documentation/x86/x86_64/boot-options.txt>.
138 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139 a trailing = on the name of any parameter states that that parameter will
140 be entered as an environment variable, whereas its absence indicates that
141 it will appear as a kernel argument readable via /proc/cmdline by programs
142 running once the system is up.
144 The number of kernel parameters is not limited, but the length of the
145 complete command line (parameters including spaces etc.) is limited to
146 a fixed number of characters. This limit depends on the architecture
147 and is between 256 and 4096 characters. It is defined in the file
148 ./include/asm/setup.h as COMMAND_LINE_SIZE.
150 Finally, the [KMG] suffix is commonly described after a number of kernel
151 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153 bytes respectively. Such letter suffixes can also be entirely omitted.
157 Advanced Configuration and Power Interface
158 Format: { force | off | strict | noirq | rsdt }
159 force -- enable ACPI if default was off
160 off -- disable ACPI if default was on
161 noirq -- do not use ACPI for IRQ routing
162 strict -- Be less tolerant of platforms that are not
163 strictly ACPI specification compliant.
164 rsdt -- prefer RSDT over (default) XSDT
165 copy_dsdt -- copy DSDT to memory
167 See also Documentation/power/runtime_pm.txt, pci=noacpi
169 acpi_rsdp= [ACPI,EFI,KEXEC]
170 Pass the RSDP address to the kernel, mostly used
171 on machines running EFI runtime service to boot the
172 second kernel for kdump.
174 acpi_apic_instance= [ACPI, IOAPIC]
176 2: use 2nd APIC table, if available
177 1,0: use 1st APIC table
180 acpi_backlight= [HW,ACPI]
181 acpi_backlight=vendor
183 If set to vendor, prefer vendor specific driver
184 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
185 of the ACPI video.ko driver.
187 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
188 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
190 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191 debug output. Bits in debug_layer correspond to a
192 _COMPONENT in an ACPI source file, e.g.,
193 #define _COMPONENT ACPI_PCI_COMPONENT
194 Bits in debug_level correspond to a level in
195 ACPI_DEBUG_PRINT statements, e.g.,
196 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
197 The debug_level mask defaults to "info". See
198 Documentation/acpi/debug.txt for more information about
199 debug layers and levels.
201 Enable processor driver info messages:
202 acpi.debug_layer=0x20000000
203 Enable PCI/PCI interrupt routing info messages:
204 acpi.debug_layer=0x400000
205 Enable AML "Debug" output, i.e., stores to the Debug
206 object while interpreting AML:
207 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
208 Enable all messages related to ACPI hardware:
209 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
211 Some values produce so much output that the system is
212 unusable. The "log_buf_len" parameter may be useful
213 if you need to capture more output.
215 acpi_irq_balance [HW,ACPI]
216 ACPI will balance active IRQs
219 acpi_irq_nobalance [HW,ACPI]
220 ACPI will not move active IRQs (default)
223 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224 Format: <irq>,<irq>...
226 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
228 Format: <irq>,<irq>...
230 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
232 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
233 Format: To spoof as Windows 98: ="Microsoft Windows"
235 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
236 acpi_osi="string1" # add string1 -- only one string
237 acpi_osi="!string2" # remove built-in string2
238 acpi_osi= # disable all strings
241 Override the pmtimer bug detection: force the kernel
242 to assume that this machine's pmtimer latches its value
243 and always returns good values.
245 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
246 Format: { level | edge | high | low }
248 acpi_serialize [HW,ACPI] force serialization of AML methods
250 acpi_skip_timer_override [HW,ACPI]
251 Recognize and ignore IRQ0/pin2 Interrupt Override.
252 For broken nForce2 BIOS resulting in XT-PIC timer.
254 acpi_sleep= [HW,ACPI] Sleep options
255 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
256 old_ordering, nonvs, sci_force_enable }
257 See Documentation/power/video.txt for information on
259 s3_beep is for debugging; it makes the PC's speaker beep
260 as soon as the kernel's real-mode entry point is called.
261 s4_nohwsig prevents ACPI hardware signature from being
262 used during resume from hibernation.
263 old_ordering causes the ACPI 1.0 ordering of the _PTS
264 control method, with respect to putting devices into
265 low power states, to be enforced (the ACPI 2.0 ordering
266 of _PTS is used by default).
267 nonvs prevents the kernel from saving/restoring the
268 ACPI NVS memory during suspend/hibernation and resume.
269 sci_force_enable causes the kernel to set SCI_EN directly
270 on resume from S1/S3 (which is against the ACPI spec,
271 but some broken systems don't work without it).
273 acpi_use_timer_override [HW,ACPI]
274 Use timer override. For some broken Nvidia NF5 boards
275 that require a timer override, but don't have HPET
277 acpi_enforce_resources= [ACPI]
278 { strict | lax | no }
279 Check for resource conflicts between native drivers
280 and ACPI OperationRegions (SystemIO and SystemMemory
281 only). IO ports and memory declared in ACPI might be
282 used by the ACPI subsystem in arbitrary AML code and
283 can interfere with legacy drivers.
284 strict (default): access to resources claimed by ACPI
285 is denied; legacy drivers trying to access reserved
286 resources will fail to bind to device using them.
287 lax: access to resources claimed by ACPI is allowed;
288 legacy drivers trying to access reserved resources
289 will bind successfully but a warning message is logged.
290 no: ACPI OperationRegions are not marked as reserved,
291 no further checks are performed.
293 add_efi_memmap [EFI; X86] Include EFI memory map in
294 kernel's map of available physical RAM.
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
303 See Documentation/sound/alsa/alsa-parameters.txt
306 Allow the default userspace alignment fault handler
307 behaviour to be specified. Bit 0 enables warnings,
308 bit 1 enables fixups, and bit 2 sends a segfault.
310 align_va_addr= [X86-64]
311 Align virtual addresses by clearing slice [14:12] when
312 allocating a VMA at process creation time. This option
313 gives you up to 3% performance improvement on AMD F15h
314 machines (where it is enabled by default) for a
315 CPU-intensive style benchmark, and it can vary highly in
316 a microbenchmark depending on workload and compiler.
318 32: only for 32-bit processes
319 64: only for 64-bit processes
320 on: enable for both 32- and 64-bit processes
321 off: disable for both 32- and 64-bit processes
323 amd_iommu= [HW,X86-64]
324 Pass parameters to the AMD IOMMU driver in the system.
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
330 off - do not initialize any AMD IOMMU found in
332 force_isolation - Force device isolation for all
333 devices. The IOMMU driver is not
334 allowed anymore to lift isolation
335 requirements as needed. This option
336 does not override iommu=pt
338 amijoy.map= [HW,JOY] Amiga joystick support
339 Map of devices attached to JOY0DAT and JOY1DAT
341 See also Documentation/input/joystick.txt
343 analog.map= [HW,JOY] Analog joystick and gamepad support
344 Specifies type or capabilities of an analog joystick
345 connected to one of 16 gameports
346 Format: <type1>,<type2>,..<type16>
349 Power management functions (SPARCstation-4/5 + deriv.)
351 Disable APC CPU standby support. SPARCstation-Fox does
352 not play well with APC CPU idle - disable it if you have
353 APC and your system crashes randomly.
355 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
356 Change the output verbosity whilst booting
357 Format: { quiet (default) | verbose | debug }
358 Change the amount of debugging information output
359 when initialising the APIC and IO-APIC components.
362 See Documentation/networking/ipv6.txt.
364 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
365 Limit apic dumping. The parameter defines the maximal
366 number of local apics being dumped. Also it is possible
367 to set it to "all" by meaning -- no limit here.
368 Format: { 1 (default) | 2 | ... | all }.
369 The parameter valid if only apic=debug or
370 apic=verbose is specified.
371 Example: apic=debug show_lapic=all
373 apm= [APM] Advanced Power Management
374 See header of arch/x86/kernel/apm_32.c.
376 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
377 Format: <io>,<irq>,<nodeID>
381 atarimouse= [HW,MOUSE] Atari Mouse
383 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
384 EzKey and similar keyboards
386 atkbd.reset= [HW] Reset keyboard during initialization
388 atkbd.set= [HW] Select keyboard code set
389 Format: <int> (2 = AT (default), 3 = PS/2)
391 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
394 atkbd.softraw= [HW] Choose between synthetic and real raw mode
395 Format: <bool> (0 = real, 1 = synthetic (default))
397 atkbd.softrepeat= [HW]
398 Use software keyboard repeat
402 baycom_epp= [HW,AX25]
405 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
407 See header of drivers/net/hamradio/baycom_par.c.
409 baycom_ser_fdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
411 Format: <io>,<irq>,<mode>[,<baud>]
412 See header of drivers/net/hamradio/baycom_ser_fdx.c.
414 baycom_ser_hdx= [HW,AX25]
415 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
416 Format: <io>,<irq>,<mode>
417 See header of drivers/net/hamradio/baycom_ser_hdx.c.
419 boot_delay= Milliseconds to delay each printk during boot.
420 Values larger than 10 seconds (10000) are changed to
424 bootmem_debug [KNL] Enable bootmem allocator debug messages.
426 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
427 bttv.radio= Most important insmod options are available as
429 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
432 bulk_remove=off [PPC] This parameter disables the use of the pSeries
433 firmware feature for flushing multiple hpte entries
436 c101= [NET] Moxa C101 synchronous serial card
438 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
439 Sometimes CPU hardware bugs make them report the cache
440 size incorrectly. The kernel will attempt work arounds
441 to fix known problems, but for some CPUs it is not
442 possible to determine what the correct size should be.
443 This option provides an override for these situations.
446 [SECURITY] Disable capabilities. This would normally
447 be used only if an alternative security model is to be
448 configured. Potentially dangerous and should only be
449 used if you are entirely sure of the consequences.
451 ccw_timeout_log [S390]
452 See Documentation/s390/CommonIO for details.
454 cgroup_disable= [KNL] Disable a particular controller
455 Format: {name of the controller(s) to disable}
456 {Currently supported controllers - "memory"}
458 checkreqprot [SELINUX] Set initial checkreqprot flag value.
459 Format: { "0" | "1" }
460 See security/selinux/Kconfig help text.
461 0 -- check protection applied by kernel (includes
462 any implied execute protection).
463 1 -- check protection requested by application.
464 Default value is set via a kernel config option.
465 Value can be changed at runtime via
466 /selinux/checkreqprot.
469 See Documentation/s390/CommonIO for details.
471 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
473 Forces specified clocksource (if available) to be used
474 when calculating gettimeofday(). If specified
475 clocksource is not available, it defaults to PIT.
476 Format: { pit | tsc | cyclone | pmtmr }
478 clocksource= Override the default clocksource
480 Override the default clocksource and use the clocksource
481 with the name specified.
482 Some clocksource names to choose from, depending on
484 [all] jiffies (this is the base, fallback clocksource)
486 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
487 pxa_timer,timer3,32k_counter,timer0_1
489 [X86-32] pit,hpet,tsc;
490 scx200_hrt on Geode; cyclone on IBM x440
498 clearcpuid=BITNUM [X86]
499 Disable CPUID feature X for the kernel. See
500 arch/x86/include/asm/cpufeature.h for the valid bit
501 numbers. Note the Linux specific bits are not necessarily
502 stable over kernel options, but the vendor specific
504 Also note that user programs calling CPUID directly
505 or using the feature without checking anything
506 will still see it. This just prevents it from
507 being used by the kernel or shown in /proc/cpuinfo.
508 Also note the kernel might malfunction if you disable
511 cmo_free_hint= [PPC] Format: { yes | no }
512 Specify whether pages are marked as being inactive
513 when they are freed. This is used in CMO environments
514 to determine OS memory pressure for page stealing by
518 code_bytes [X86] How many bytes of object code to print
523 com20020= [HW,NET] ARCnet - COM20020 chipset
525 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
527 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
531 ARCnet - COM90xx chipset (memory-mapped buffers)
532 Format: <io>[,<irq>[,<memstart>]]
534 condev= [HW,S390] console device
537 console= [KNL] Output console device and options.
539 tty<n> Use the virtual console device <n>.
543 Use the specified serial port. The options are of
544 the form "bbbbpnf", where "bbbb" is the baud rate,
545 "p" is parity ("n", "o", or "e"), "n" is number of
546 bits, and "f" is flow control ("r" for RTS or
547 omit it). Default is "9600n8".
549 See Documentation/serial-console.txt for more
551 Documentation/networking/netconsole.txt for an
554 uart[8250],io,<addr>[,options]
555 uart[8250],mmio,<addr>[,options]
556 Start an early, polled-mode console on the 8250/16550
557 UART at the specified I/O port or MMIO address,
558 switching to the matching ttyS device later. The
559 options are the same as for ttyS, above.
561 If the device connected to the port is not a TTY but a braille
562 device, prepend "brl," before the device type, for instance
564 For now, only VisioBraille is supported.
566 consoleblank= [KNL] The console blank (screen saver) timeout in
567 seconds. Defaults to 10*60 = 10mins. A value of 0
568 disables the blank timer.
571 [KNL] Change the default value for
572 /proc/<pid>/coredump_filter.
573 See also Documentation/filesystems/proc.txt.
575 cpuidle.off=1 [CPU_IDLE]
576 disable the cpuidle sub-system
578 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
580 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
582 crashkernel=size[KMG][@offset[KMG]]
583 [KNL] Using kexec, Linux can switch to a 'crash kernel'
584 upon panic. This parameter reserves the physical
585 memory region [offset, offset + size] for that kernel
586 image. If '@offset' is omitted, then a suitable offset
587 is selected automatically. Check
588 Documentation/kdump/kdump.txt for further details.
590 crashkernel=range1:size1[,range2:size2,...][@offset]
591 [KNL] Same as above, but depends on the memory
592 in the running system. The syntax of range is
593 start-[end] where start and end are both
594 a memory unit (amount[KMG]). See also
595 Documentation/kdump/kdump.txt for an example.
600 cs89x0_media= [HW,NET]
601 Format: { rj45 | aui | bnc }
604 See header of drivers/s390/block/dasd_devmap.c.
606 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
607 (one device per port)
608 Format: <port#>,<type>
609 See also Documentation/input/joystick-parport.txt
611 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
612 time. See Documentation/dynamic-debug-howto.txt for
615 debug [KNL] Enable kernel debugging (events log level).
618 [KNL] verbose self-tests
620 Print debugging info while doing the locking API
622 We default to 0 (no extra messages), setting it to
623 1 will print _a lot_ more information - normally
624 only useful to kernel developers.
626 debug_objects [KNL] Enable object debugging
629 [KNL] Disable object debugging
631 debugpat [X86] Enable PAT debugging
633 decnet.addr= [HW,NET]
634 Format: <area>[,<node>]
635 See also Documentation/networking/decnet.txt.
638 [same as hugepagesz=] The size of the default
639 HugeTLB page size. This is the size represented by
640 the legacy /proc/ hugepages APIs, used for SHM, and
641 default size when mounting hugetlbfs filesystems.
642 Defaults to the default architecture's huge page size
646 Set number of hash buckets for dentry cache.
649 IO parameters + enable/disable command.
651 digiepca= [HW,SERIAL]
652 See drivers/char/README.epca and
653 Documentation/serial/digiepca.txt.
656 See Documentation/networking/ipv6.txt.
658 disable_ddw [PPC/PSERIES]
659 Disable Dynamic DMA Window support. Use this if
660 to workaround buggy firmware.
663 See Documentation/networking/ipv6.txt.
665 disable_mtrr_cleanup [X86]
666 The kernel tries to adjust MTRR layout from continuous
667 to discrete, to make X server driver able to add WB
668 entry later. This parameter disables that.
670 disable_mtrr_trim [X86, Intel and AMD only]
671 By default the kernel will trim any uncacheable
672 memory out of your available memory pool based on
673 MTRR settings. This parameter disables that behavior,
674 possibly causing your machine to run very slowly.
676 disable_timer_pin_1 [X86]
677 Disable PIN 1 of APIC timer
678 Can be useful to work around chipset bugs.
680 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
681 this option disables the debugging code at boot.
683 dma_debug_entries=<number>
684 This option allows to tune the number of preallocated
685 entries for DMA-API debugging code. One entry is
686 required per DMA-API allocation. Use this if the
687 DMA-API debugging code disables itself because the
688 architectural default is too low.
690 dma_debug_driver=<driver_name>
691 With this option the DMA-API debugging driver
692 filter feature can be enabled at boot time. Just
693 pass the driver to filter for as the parameter.
694 The filter can be disabled or changed to another
695 driver later using sysfs.
699 earlycon= [KNL] Output early console device and options.
700 uart[8250],io,<addr>[,options]
701 uart[8250],mmio,<addr>[,options]
702 uart[8250],mmio32,<addr>[,options]
703 Start an early, polled-mode console on the 8250/16550
704 UART at the specified I/O port or MMIO address.
705 MMIO inter-register address stride is either 8-bit
706 (mmio) or 32-bit (mmio32).
707 The options are the same as for ttyS, above.
709 earlyprintk= [X86,SH,BLACKFIN]
711 earlyprintk=serial[,ttySn[,baudrate]]
712 earlyprintk=ttySn[,baudrate]
713 earlyprintk=dbgp[debugController#]
715 Append ",keep" to not disable it when the real console
718 Only vga or serial or usb debug port at a time.
720 Currently only ttyS0 and ttyS1 are supported.
722 Interaction with the standard serial driver is not
725 The VGA output is eventually overwritten by the real
728 ekgdboc= [X86,KGDB] Allow early kernel console debugging
731 This is designed to be used in conjunction with
732 the boot argument: earlyprintk=vga
735 Format: {"off" | "on" | "skip[mbr]"}
737 eisa_irq_edge= [PARISC,HW]
738 See header of drivers/parisc/eisa.c.
741 See comment before function elanfreq_setup() in
742 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
745 Format: {"cfq" | "deadline" | "noop"}
746 See Documentation/block/cfq-iosched.txt and
747 Documentation/block/deadline-iosched.txt for details.
749 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
750 Specifies physical address of start of kernel core
751 image elf header and optionally the size. Generally
752 kexec loader will pass this option to capture kernel.
753 See Documentation/kdump/kdump.txt for details.
755 enable_mtrr_cleanup [X86]
756 The kernel tries to adjust MTRR layout from continuous
757 to discrete, to make X server driver able to add WB
758 entry later. This parameter enables that.
760 enable_timer_pin_1 [X86]
761 Enable PIN 1 of APIC timer
762 Can be useful to work around chipset bugs
763 (in particular on some ATI chipsets).
764 The kernel tries to set a reasonable default.
766 enforcing [SELINUX] Set initial enforcing status.
768 See security/selinux/Kconfig help text.
769 0 -- permissive (log only, no denials).
770 1 -- enforcing (deny and log).
772 Value can be changed at runtime via /selinux/enforce.
775 Disable Error Record Serialization Table (ERST)
778 ether= [HW,NET] Ethernet cards parameters
779 This option is obsoleted by the "netdev=" option, which
780 has equivalent usage. See its documentation for details.
784 Permit 'security.evm' to be updated regardless of
785 current integrity status.
789 fail_make_request=[KNL]
790 General fault injection mechanism.
791 Format: <interval>,<probability>,<space>,<times>
792 See also Documentation/fault-injection/.
795 See Documentation/blockdev/floppy.txt.
797 force_pal_cache_flush
798 [IA-64] Avoid check_sal_cache_flush which may hang on
799 buggy SAL_CACHE_FLUSH implementations. Using this
800 parameter will force ia64_sal_cache_flush to call
801 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
804 [FTRACE] will set and start the specified tracer
805 as early as possible in order to facilitate early
808 ftrace_dump_on_oops[=orig_cpu]
809 [FTRACE] will dump the trace buffers on oops.
810 If no parameter is passed, ftrace will dump
811 buffers of all CPUs, but if you pass orig_cpu, it will
812 dump only the buffer of the CPU that triggered the
815 ftrace_filter=[function-list]
816 [FTRACE] Limit the functions traced by the function
817 tracer at boot up. function-list is a comma separated
818 list of functions. This list can be changed at run
819 time by the set_ftrace_filter file in the debugfs
822 ftrace_notrace=[function-list]
823 [FTRACE] Do not trace the functions specified in
824 function-list. This list can be changed at run time
825 by the set_ftrace_notrace file in the debugfs
828 ftrace_graph_filter=[function-list]
829 [FTRACE] Limit the top level callers functions traced
830 by the function graph tracer at boot up.
831 function-list is a comma separated list of functions
832 that can be changed at run time by the
833 set_graph_function file in the debugfs tracing directory.
836 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
837 support via parallel port (up to 5 devices per port)
838 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
839 See also Documentation/input/joystick-parport.txt
843 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
847 gcov_persist= [GCOV] When non-zero (default), profiling data for
848 kernel modules is saved and remains accessible via
849 debugfs, even when the module is unloaded/reloaded.
850 When zero, profiling data is discarded and associated
851 debugfs files are removed at module unload time.
853 gpt [EFI] Forces disk with valid GPT signature but
854 invalid Protective MBR to be treated as GPT.
856 hashdist= [KNL,NUMA] Large hashes allocated during boot
857 are distributed across NUMA nodes. Defaults on
858 for 64-bit NUMA, off otherwise.
859 Format: 0 | 1 (for off | on)
861 hcl= [IA-64] SGI's Hardware Graph compatibility layer
863 hd= [EIDE] (E)IDE hard drive subsystem geometry
864 Format: <cyl>,<head>,<sect>
867 Disable Hardware Error Source Table (HEST) support;
868 corresponding firmware-first mode error processing
869 logic will be disabled.
871 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
872 size of <nn>. This works even on boxes that have no
873 highmem otherwise. This also works to reduce highmem
874 size on bigger boxes.
876 highres= [KNL] Enable/disable high resolution timer mode.
877 Valid parameters: "on", "off"
881 See Documentation/isdn/README.HiSax.
885 hpet= [X86-32,HPET] option to control HPET usage
886 Format: { enable (default) | disable | force |
888 disable: disable HPET and use PIT instead
889 force: allow force enabled of undocumented chips (ICH4,
891 verbose: show contents of HPET registers during setup
893 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
894 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
895 On x86-64 and powerpc, this option can be specified
896 multiple times interleaved with hugepages= to reserve
897 huge pages of different sizes. Valid pages sizes on
898 x86-64 are 2M (when the CPU supports "pse") and 1G
899 (when the CPU supports the "pdpe1gb" cpuinfo flag)
900 Note that 1GB pages can only be allocated at boot time
901 using hugepages= and not freed afterwards.
903 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
904 terminal devices. Valid values: 0..8
905 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
906 If specified, z/VM IUCV HVC accepts connections
907 from listed z/VM user IDs only.
910 Do not unregister boot console at start. This is only
911 useful for debugging when something happens in the window
912 between unregistering the boot console and initializing
915 i2c_bus= [HW] Override the default board specific I2C bus speed
916 or register an additional I2C bus that is not
917 registered from board initialization code.
921 i8042.debug [HW] Toggle i8042 debug mode
922 i8042.direct [HW] Put keyboard port into non-translated mode
923 i8042.dumbkbd [HW] Pretend that controller can only read data from
924 keyboard and cannot control its state
925 (Don't attempt to blink the leds)
926 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
927 i8042.nokbd [HW] Don't check/create keyboard port
928 i8042.noloop [HW] Disable the AUX Loopback command while probing
930 i8042.nomux [HW] Don't check presence of an active multiplexing
932 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
934 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
935 i8042.reset [HW] Reset the controller during init and cleanup
936 i8042.unlock [HW] Unlock (ignore) the keylock
940 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
941 indicates that the driver is running on unsupported
943 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
944 does not match list of supported models.
946 [HW] Report power status in /proc/i8k
947 (disabled by default)
948 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
952 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
954 ide-core.nodma= [HW] (E)IDE subsystem
955 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
956 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
957 .cdrom .chs .ignore_cable are additional options
958 See Documentation/ide/ide.txt.
960 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
961 Claim all unknown PCI IDE storage controllers.
964 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
965 Poll forces a polling idle loop that can slightly
966 improve the performance of waking up a idle CPU, but
967 will use a lot of power and make the system run hot.
969 idle=mwait: On systems which support MONITOR/MWAIT but
970 the kernel chose to not use it because it doesn't save
971 as much power as a normal idle loop, use the
972 MONITOR/MWAIT idle loop anyways. Performance should be
973 the same as idle=poll.
974 idle=halt: Halt is forced to be used for CPU idle.
975 In such case C2/C3 won't be used again.
976 idle=nomwait: Disable mwait for CPU C-states
978 ignore_loglevel [KNL]
979 Ignore loglevel setting - this will print /all/
980 kernel messages to the console. Useful for debugging.
981 We also add it as printk module parameter, so users
982 could change it dynamically, usually by
983 /sys/module/printk/parameters/ignore_loglevel.
986 Set number of hash buckets for inode cache.
989 Format: { "0" | "1" }
990 0 -- integrity auditing messages. (Default)
991 1 -- enable informational integrity auditing messages.
994 Format: { "sha1" | "md5" }
998 Load a policy which meets the needs of the Trusted
999 Computing Base. This means IMA will measure all
1000 programs exec'd, files mmap'd for exec, and all files
1001 opened for read by uid=0.
1005 Run specified binary instead of /sbin/init as init
1008 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1009 for working out where the kernel is dying during
1012 initrd= [BOOT] Specify the location of the initial ramdisk
1014 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1017 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1019 Enable intel iommu driver.
1021 Disable intel iommu driver.
1022 igfx_off [Default Off]
1023 By default, gfx is mapped as normal device. If a gfx
1024 device has a dedicated DMAR unit, the DMAR unit is
1025 bypassed by not enabling DMAR with this option. In
1026 this case, gfx device will use physical address for
1029 With this option iommu will not optimize to look
1030 for io virtual address below 32-bit forcing dual
1031 address cycle on pci bus for cards supporting greater
1032 than 32-bit addressing. The default is to look
1033 for translation below 32-bit and if not available
1034 then look in the higher range.
1035 strict [Default Off]
1036 With this option on every unmap_single operation will
1037 result in a hardware IOTLB flush operation as opposed
1038 to batching them for performance.
1039 sp_off [Default Off]
1040 By default, super page will be supported if Intel IOMMU
1041 has the capability. With this option, super page will
1043 intremap= [X86-64, Intel-IOMMU]
1044 on enable Interrupt Remapping (default)
1045 off disable Interrupt Remapping
1046 nosid disable Source ID checking
1048 BIOS x2APIC opt-out request will be ignored
1052 iomem= Disable strict checking of access to MMIO memory
1053 strict regions from userspace.
1068 group_mf [x86, IA-64]
1071 io7= [HW] IO7 for Marvel based alpha systems
1072 See comment before marvel_specify_io7 in
1073 arch/alpha/kernel/core_marvel.c.
1075 io_delay= [X86] I/O delay method
1077 Standard port 0x80 based delay
1079 Alternate port 0xed based delay (needed on some systems)
1081 Simple two microseconds delay
1086 See Documentation/filesystems/nfs/nfsroot.txt.
1088 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1089 See comment before ip2_setup() in
1090 drivers/char/ip2/ip2base.c.
1093 When an interrupt is not handled search all handlers
1094 for it. Intended to get systems with badly broken
1098 When an interrupt is not handled search all handlers
1099 for it. Also check all handlers each timer
1100 interrupt. Intended to get systems with badly broken
1104 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1106 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1108 <cpu number>,...,<cpu number>
1110 <cpu number>-<cpu number>
1111 (must be a positive range in ascending order)
1113 <cpu number>,...,<cpu number>-<cpu number>
1115 This option can be used to specify one or more CPUs
1116 to isolate from the general SMP balancing and scheduling
1117 algorithms. You can move a process onto or off an
1118 "isolated" CPU via the CPU affinity syscalls or cpuset.
1119 <cpu number> begins at 0 and the maximum value is
1120 "number of CPUs in system - 1".
1122 This option is the preferred way to isolate CPUs. The
1123 alternative -- manually setting the CPU mask of all
1124 tasks in the system -- can cause problems and
1125 suboptimal load balancer performance.
1129 js= [HW,JOY] Analog joystick
1130 See Documentation/input/joystick.txt.
1134 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1135 specifies the amount of memory usable by the kernel
1136 for non-movable allocations. The requested amount is
1137 spread evenly throughout all nodes in the system. The
1138 remaining memory in each node is used for Movable
1139 pages. In the event, a node is too small to have both
1140 kernelcore and Movable pages, kernelcore pages will
1141 take priority and other nodes will have a larger number
1142 of kernelcore pages. The Movable zone is used for the
1143 allocation of pages that may be reclaimed or moved
1144 by the page migration subsystem. This means that
1145 HugeTLB pages may not be allocated from this zone.
1146 Note that allocations like PTEs-from-HighMem still
1147 use the HighMem zone if it exists, and the Normal
1148 zone if it does not.
1150 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1151 Format: <Controller#>[,poll interval]
1152 The controller # is the number of the ehci usb debug
1153 port as it is probed via PCI. The poll interval is
1154 optional and is the number seconds in between
1155 each poll cycle to the debug port in case you need
1156 the functionality for interrupting the kernel with
1157 gdb or control-c on the dbgp connection. When
1158 not using this parameter you use sysrq-g to break into
1159 the kernel debugger.
1161 kgdboc= [KGDB,HW] kgdb over consoles.
1162 Requires a tty driver that supports console polling,
1163 or a supported polling keyboard driver (non-usb).
1164 Serial only format: <serial_device>[,baud]
1165 keyboard only format: kbd
1166 keyboard and serial format: kbd,<serial_device>[,baud]
1167 Optional Kernel mode setting:
1168 kms, kbd format: kms,kbd
1169 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1171 kgdbwait [KGDB] Stop kernel execution and enter the
1172 kernel debugger at the earliest opportunity.
1174 kmac= [MIPS] korina ethernet MAC address.
1175 Configure the RouterBoard 532 series on-chip
1176 Ethernet adapter MAC address.
1178 kmemleak= [KNL] Boot-time kmemleak enable/disable
1179 Valid arguments: on, off
1182 kstack=N [X86] Print N words from the kernel stack
1185 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1186 Default is 0 (don't ignore, but inject #GP)
1188 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1189 Default is 1 (enabled)
1191 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1195 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1196 Default is 1 (enabled)
1198 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1200 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1202 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1203 (virtualized MMU) support on capable Intel chips.
1204 Default is 1 (enabled)
1206 kvm-intel.emulate_invalid_guest_state=
1207 [KVM,Intel] Enable emulation of invalid guest states
1208 Default is 0 (disabled)
1210 kvm-intel.flexpriority=
1211 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1212 Default is 1 (enabled)
1215 [KVM,Intel] Enable VMX nesting (nVMX).
1216 Default is 0 (disabled)
1218 kvm-intel.unrestricted_guest=
1219 [KVM,Intel] Disable unrestricted guest feature
1220 (virtualized real and unpaged mode) on capable
1221 Intel chips. Default is 1 (enabled)
1223 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1224 feature (tagged TLBs) on capable Intel chips.
1225 Default is 1 (enabled)
1231 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1234 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1237 libata.dma= [LIBATA] DMA control
1238 libata.dma=0 Disable all PATA and SATA DMA
1239 libata.dma=1 PATA and SATA Disk DMA only
1240 libata.dma=2 ATAPI (CDROM) DMA only
1241 libata.dma=4 Compact Flash DMA only
1242 Combinations also work, so libata.dma=3 enables DMA
1243 for disks and CDROMs, but not CFs.
1245 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1246 libata.ignore_hpa=0 keep BIOS limits (default)
1247 libata.ignore_hpa=1 ignore limits, using full disk
1249 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1253 libata.force= [LIBATA] Force configurations. The format is comma
1254 separated list of "[ID:]VAL" where ID is
1255 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1256 matching port, link or device. Basically, it matches
1257 the ATA ID string printed on console by libata. If
1258 the whole ID part is omitted, the last PORT and DEVICE
1259 values are used. If ID hasn't been specified yet, the
1260 configuration applies to all ports, links and devices.
1262 If only DEVICE is omitted, the parameter applies to
1263 the port and all links and devices behind it. DEVICE
1264 number of 0 either selects the first device or the
1265 first fan-out link behind PMP device. It does not
1266 select the host link. DEVICE number of 15 selects the
1267 host link and device attached to it.
1269 The VAL specifies the configuration to force. As long
1270 as there's no ambiguity shortcut notation is allowed.
1271 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1272 The following configurations can be forced.
1274 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1275 Any ID with matching PORT is used.
1277 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1279 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1280 udma[/][16,25,33,44,66,100,133] notation is also
1283 * [no]ncq: Turn on or off NCQ.
1285 * nohrst, nosrst, norst: suppress hard, soft
1288 * dump_id: dump IDENTIFY data.
1290 If there are multiple matching configurations changing
1291 the same attribute, the last one is used.
1293 memblock=debug [KNL] Enable memblock debug messages.
1295 load_ramdisk= [RAM] List of ramdisks to load from floppy
1296 See Documentation/blockdev/ramdisk.txt.
1298 lockd.nlm_grace_period=P [NFS] Assign grace period.
1301 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1304 lockd.nlm_timeout=T [NFS] Assign timeout value.
1307 lockd.nlm_udpport=M [NFS] Assign UDP port.
1310 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1313 loglevel= All Kernel Messages with a loglevel smaller than the
1314 console loglevel will be printed to the console. It can
1315 also be changed with klogd or other programs. The
1316 loglevels are defined as follows:
1318 0 (KERN_EMERG) system is unusable
1319 1 (KERN_ALERT) action must be taken immediately
1320 2 (KERN_CRIT) critical conditions
1321 3 (KERN_ERR) error conditions
1322 4 (KERN_WARNING) warning conditions
1323 5 (KERN_NOTICE) normal but significant condition
1324 6 (KERN_INFO) informational
1325 7 (KERN_DEBUG) debug-level messages
1327 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1328 in bytes. n must be a power of two. The default
1329 size is set in the kernel config file.
1331 logo.nologo [FB] Disables display of the built-in Linux logo.
1332 This may be used to provide more screen space for
1333 kernel log messages and is useful when debugging
1334 kernel boot problems.
1336 lp=0 [LP] Specify parallel ports to use, e.g,
1337 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1338 lp=reset first parallel port). 'lp=0' disables the
1339 lp=auto printer driver. 'lp=reset' (which can be
1340 specified in addition to the ports) causes
1341 attached printers to be reset. Using
1342 lp=port1,port2,... specifies the parallel ports
1343 to associate lp devices with, starting with
1344 lp0. A port specification may be 'none' to skip
1345 that lp device, or a parport name such as
1346 'parport0'. Specifying 'lp=auto' instead of a
1347 port specification list means that device IDs
1348 from each port should be examined, to see if
1349 an IEEE 1284-compliant printer is attached; if
1350 so, the driver will manage that printer.
1351 See also header of drivers/char/lp.c.
1354 Sets loops_per_jiffy to given constant, thus avoiding
1355 time-consuming boot-time autodetection (up to 250 ms per
1356 CPU). 0 enables autodetection (default). To determine
1357 the correct value for your kernel, boot with normal
1358 autodetection and see what value is printed. Note that
1359 on SMP systems the preset will be applied to all CPUs,
1360 which is likely to cause problems if your CPUs need
1361 significantly divergent settings. An incorrect value
1362 will cause delays in the kernel to be wrong, leading to
1363 unpredictable I/O errors and other breakage. Although
1364 unlikely, in the extreme case this might damage your
1368 Format: <io>,<irq>,<dma>
1370 machvec= [IA-64] Force the use of a particular machine-vector
1371 (machvec) in a generic kernel.
1372 Example: machvec=hpzx1_swiotlb
1374 machtype= [Loongson] Share the same kernel image file between different
1376 Example: machtype=lemote-yeeloong-2f-7inch
1378 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1379 than or equal to this physical address is ignored.
1381 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1382 should make use of. maxcpus=n : n >= 0 limits the
1383 kernel to using 'n' processors. n=0 is a special case,
1384 it is equivalent to "nosmp", which also disables
1387 max_loop= [LOOP] The number of loop block devices that get
1388 (loop.max_loop) unconditionally pre-created at init time. The default
1389 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1390 of statically allocating a predefined number, loop
1391 devices can be requested on-demand with the
1392 /dev/loop-control interface.
1396 mce [X86-32] Machine Check Exception
1398 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1400 md= [HW] RAID subsystems devices and level
1401 See Documentation/md.txt.
1404 Format: <first>,<last>
1405 Specifies range of consoles to be captured by the MDA.
1407 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1408 Amount of memory to be used when the kernel is not able
1409 to see the whole system memory or for test.
1410 [X86-32] Use together with memmap= to avoid physical
1411 address space collisions. Without memmap= PCI devices
1412 could be placed at addresses belonging to unused RAM.
1414 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1418 [KNL,SH] Allow user to override the default size for
1419 per-device physically contiguous DMA buffers.
1421 memmap=exactmap [KNL,X86] Enable setting of an exact
1422 E820 memory map, as specified by the user.
1423 Such memmap=exactmap lines can be constructed based on
1424 BIOS output or other requirements. See the memmap=nn@ss
1427 memmap=nn[KMG]@ss[KMG]
1428 [KNL] Force usage of a specific region of memory
1429 Region of memory to be used, from ss to ss+nn.
1431 memmap=nn[KMG]#ss[KMG]
1432 [KNL,ACPI] Mark specific memory as ACPI data.
1433 Region of memory to be used, from ss to ss+nn.
1435 memmap=nn[KMG]$ss[KMG]
1436 [KNL,ACPI] Mark specific memory as reserved.
1437 Region of memory to be used, from ss to ss+nn.
1438 Example: Exclude memory from 0x18690000-0x1869ffff
1439 memmap=64K$0x18690000
1441 memmap=0x10000$0x18690000
1443 memory_corruption_check=0/1 [X86]
1444 Some BIOSes seem to corrupt the first 64k of
1445 memory when doing things like suspend/resume.
1446 Setting this option will scan the memory
1447 looking for corruption. Enabling this will
1448 both detect corruption and prevent the kernel
1449 from using the memory being corrupted.
1450 However, its intended as a diagnostic tool; if
1451 repeatable BIOS-originated corruption always
1452 affects the same memory, you can use memmap=
1453 to prevent the kernel from using that memory.
1455 memory_corruption_check_size=size [X86]
1456 By default it checks for corruption in the low
1457 64k, making this memory unavailable for normal
1458 use. Use this parameter to scan for
1459 corruption in more or less memory.
1461 memory_corruption_check_period=seconds [X86]
1462 By default it checks for corruption every 60
1463 seconds. Use this parameter to check at some
1464 other rate. 0 disables periodic checking.
1466 memtest= [KNL,X86] Enable memtest
1468 default : 0 <disable>
1469 Specifies the number of memtest passes to be
1470 performed. Each pass selects another test
1471 pattern from a given set of patterns. Memtest
1472 fills the memory with this pattern, validates
1473 memory contents and reserves bad memory
1474 regions that are detected.
1476 meye.*= [HW] Set MotionEye Camera parameters
1477 See Documentation/video4linux/meye.txt.
1479 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1480 Multi-Function General Purpose Timers on AMD Geode
1483 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1484 the BIOS has incorrectly applied a workaround. TinyBIOS
1485 version 0.98 is known to be affected, 0.99 fixes the
1486 problem by letting the user disable the workaround.
1490 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1491 physical address is ignored.
1493 mini2440= [ARM,HW,KNL]
1494 Format:[0..2][b][c][t]
1496 MINI2440 configuration specification:
1497 0 - The attached screen is the 3.5" TFT
1498 1 - The attached screen is the 7" TFT
1499 2 - The VGA Shield is attached (1024x768)
1500 Leaving out the screen size parameter will not load
1501 the TFT driver, and the framebuffer will be left
1503 b - Enable backlight. The TFT backlight pin will be
1504 linked to the kernel VESA blanking code and a GPIO
1505 LED. This parameter is not necessary when using the
1507 c - Enable the s3c camera interface.
1508 t - Reserved for enabling touchscreen support. The
1509 touchscreen support is not enabled in the mainstream
1510 kernel as of 2.6.30, a preliminary port can be found
1511 in the "bleeding edge" mini2440 support kernel at
1512 http://repo.or.cz/w/linux-2.6/mini2440.git
1515 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1516 parameter allows control of the logging verbosity for
1517 the additional memory initialisation checks. A value
1518 of 0 disables mminit logging and a level of 4 will
1519 log everything. Information is printed at KERN_DEBUG
1520 so loglevel=8 may also need to be specified.
1523 [MOUSE] Maximum time between finger touching and
1524 leaving touchpad surface for touch to be considered
1525 a tap and be reported as a left button click (for
1526 touchpads working in absolute mode only).
1528 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1529 reporting absolute coordinates, such as tablets
1530 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1531 reporting absolute coordinates, such as tablets
1533 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1534 is similar to kernelcore except it specifies the
1535 amount of memory used for migratable allocations.
1536 If both kernelcore and movablecore is specified,
1537 then kernelcore will be at *least* the specified
1538 value but may be more. If movablecore on its own
1539 is specified, the administrator must be careful
1540 that the amount of memory usable for all allocations
1543 MTD_Partition= [MTD]
1544 Format: <name>,<region-number>,<size>,<offset>
1546 MTD_Region= [MTD] Format:
1547 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1550 See drivers/mtd/cmdlinepart.c.
1552 multitce=off [PPC] This parameter disables the use of the pSeries
1553 firmware feature for updating multiple TCE entries
1556 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1558 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1560 boundary - index of last SLC block on Flex-OneNAND.
1561 The remaining blocks are configured as MLC blocks.
1562 lock - Configure if Flex-OneNAND boundary should be locked.
1563 Once locked, the boundary cannot be changed.
1564 1 indicates lock status, 0 indicates unlock status.
1567 ARM/S3C2412 JIVE boot control
1569 See arch/arm/mach-s3c2412/mach-jive.c
1571 mtouchusb.raw_coordinates=
1572 [HW] Make the MicroTouch USB driver use raw coordinates
1573 ('y', default) or cooked coordinates ('n')
1575 mtrr_chunk_size=nn[KMG] [X86]
1576 used for mtrr cleanup. It is largest continuous chunk
1577 that could hold holes aka. UC entries.
1579 mtrr_gran_size=nn[KMG] [X86]
1580 Used for mtrr cleanup. It is granularity of mtrr block.
1582 Large value could prevent small alignment from
1585 mtrr_spare_reg_nr=n [X86]
1587 Range: 0,7 : spare reg number
1589 Used for mtrr cleanup. It is spare mtrr entries number.
1590 Set to 2 or more if your graphical card needs more.
1592 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
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
1607 nfsaddrs= [NFS] Deprecated. Use ip= instead.
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 nfsrootdebug [NFS] enable nfsroot debugging messages.
1614 See Documentation/filesystems/nfs/nfsroot.txt.
1616 nfs.callback_tcpport=
1617 [NFS] set the TCP port on which the NFSv4 callback
1618 channel should listen.
1621 [NFS] sets the pathname to the program which is used
1622 to update the NFS client cache entries.
1624 nfs.cache_getent_timeout=
1625 [NFS] sets the timeout after which an attempt to
1626 update a cache entry is deemed to have failed.
1628 nfs.idmap_cache_timeout=
1629 [NFS] set the maximum lifetime for idmapper cache
1633 [NFS] enable 64-bit inode numbers.
1634 If zero, the NFS client will fake up a 32-bit inode
1635 number for the readdir() and stat() syscalls instead
1636 of returning the full 64-bit number.
1637 The default is to return 64-bit inode numbers.
1639 nfs.nfs4_disable_idmapping=
1640 [NFSv4] When set, this option disables the NFSv4
1641 idmapper on the client, but only if the mount
1642 is using the 'sec=sys' security flavour. This may
1643 make migration from legacy NFSv2/v3 systems easier
1644 provided that the server has the appropriate support.
1645 The default is to always enable NFSv4 idmapping.
1647 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1648 when a NMI is triggered.
1649 Format: [state][,regs][,debounce][,die]
1651 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1652 Format: [panic,][nopanic,][num]
1654 0 - turn nmi_watchdog off
1655 When panic is specified, panic when an NMI watchdog
1656 timeout occurs (or 'nopanic' to override the opposite
1658 This is useful when you use a panic=... timeout and
1659 need the box quickly up again.
1661 netpoll.carrier_timeout=
1662 [NET] Specifies amount of time (in seconds) that
1663 netpoll should wait for a carrier. By default netpoll
1666 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1667 emulation library even if a 387 maths coprocessor
1671 [HW] Never suspend the console
1672 Disable suspending of consoles during suspend and
1673 hibernate operations. Once disabled, debugging
1674 messages can reach various consoles while the rest
1675 of the system is being put to sleep (ie, while
1676 debugging driver suspend/resume hooks). This may
1677 not work reliably with all consoles, but is known
1678 to work with serial and VGA consoles.
1679 To facilitate more flexible debugging, we also add
1680 console_suspend, a printk module parameter to control
1681 it. Users could use console_suspend (usually
1682 /sys/module/printk/parameters/console_suspend) to
1683 turn on/off it dynamically.
1685 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1686 caches in the slab allocator. Saves per-node memory,
1687 but will impact performance.
1691 noapic [SMP,APIC] Tells the kernel to not make use of any
1692 IOAPICs that may be present in the system.
1694 noautogroup Disable scheduler automatic task group creation.
1696 nobats [PPC] Do not use BATs for mapping kernel lowmem
1697 on "Classic" PPC cores.
1701 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1703 nodelayacct [KNL] Disable per-task delay accounting
1705 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1707 nodsp [SH] Disable hardware DSP at boot time.
1709 noefi [X86] Disable EFI runtime services support.
1714 On X86-32 available only on PAE configured kernels.
1715 noexec=on: enable non-executable mappings (default)
1716 noexec=off: disable non-executable mappings
1719 Disable SMEP (Supervisor Mode Execution Protection)
1720 even if it is supported by processor.
1723 This affects only 32-bit executables.
1724 noexec32=on: enable non-executable mappings (default)
1725 read doesn't imply executable mappings
1726 noexec32=off: disable non-executable mappings
1727 read implies executable mappings
1729 nofpu [SH] Disable hardware FPU at boot time.
1731 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1732 register save and restore. The kernel will only save
1733 legacy floating-point registers on task switch.
1735 noxsave [BUGS=X86] Disables x86 extended register state save
1736 and restore using xsave. The kernel will fallback to
1737 enabling legacy floating-point and sse state.
1739 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1740 wfi(ARM) instruction doesn't work correctly and not to
1741 use it. This is also useful when using JTAG debugger.
1743 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1744 instruction doesn't work correctly and not to
1747 no_file_caps Tells the kernel not to honor file capabilities. The
1748 only way then for a file to be executed with privilege
1749 is to be setuid root or executed by root.
1751 nohalt [IA-64] Tells the kernel not to use the power saving
1752 function PAL_HALT_LIGHT when idle. This increases
1753 power-consumption. On the positive side, it reduces
1754 interrupt wake-up latency, which may improve performance
1755 in certain environments such as networked servers or
1758 nohz= [KNL] Boottime enable/disable dynamic ticks
1759 Valid arguments: on, off
1762 noiotrap [SH] Disables trapped I/O port accesses.
1764 noirqdebug [X86-32] Disables the code which attempts to detect and
1765 disable unhandled interrupt sources.
1767 no_timer_check [X86,APIC] Disables the code which tests for
1768 broken timer IRQ sources.
1770 noisapnp [ISAPNP] Disables ISA PnP code.
1772 noinitrd [RAM] Tells the kernel not to load any configured
1775 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1777 [Deprecated - use intremap=off]
1781 nojitter [IA-64] Disables jitter checking for ITC timers.
1783 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1785 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1788 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1789 steal time is computed, but won't influence scheduler
1792 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1794 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1796 noltlbs [PPC] Do not use large page/tlb entries for kernel
1797 lowmem mapping on PPC40x.
1799 nomca [IA-64] Disable machine check abort handling
1801 nomce [X86-32] Machine Check Exception
1803 nomfgpt [X86-32] Disable Multi-Function General Purpose
1804 Timer usage (for AMD Geode machines).
1806 nopat [X86] Disable PAT (page attribute table extension of
1807 pagetables) support.
1809 norandmaps Don't use address space randomization. Equivalent to
1810 echo 0 > /proc/sys/kernel/randomize_va_space
1812 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1814 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1815 with UP alternatives
1817 noresidual [PPC] Don't use residual data on PReP machines.
1819 nordrand [X86] Disable the direct use of the RDRAND
1820 instruction even if it is supported by the
1821 processor. RDRAND is still available to user
1824 noresume [SWSUSP] Disables resume and restores original swap
1827 no-scroll [VGA] Disables scrollback.
1828 This is required for the Braillex ib80-piezo Braille
1829 reader made by F.H. Papenmeier (Germany).
1833 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1835 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1836 and disable the IO APIC. legacy for "maxcpus=0".
1838 nosoftlockup [KNL] Disable the soft-lockup detector.
1840 nosync [HW,M68K] Disables sync negotiation for all devices.
1842 notsc [BUGS=X86-32] Disable Time Stamp Counter
1844 nousb [USB] Disable the USB subsystem
1846 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1850 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1852 nptcg= [IA-64] Override max number of concurrent global TLB
1853 purges which is reported from either PAL_VM_SUMMARY or
1856 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1857 could support. nr_cpus=n : n >= 1 limits the kernel to
1858 supporting 'n' processors. Later in runtime you can not
1859 use hotplug cpu feature to put more cpu back to online.
1860 just like you compile the kernel NR_CPUS=n
1862 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1864 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1865 one of ['zone', 'node', 'default'] can be specified
1866 This can be set from sysctl after boot.
1867 See Documentation/sysctl/vm.txt for details.
1869 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1870 See Documentation/debugging-via-ohci1394.txt for more
1873 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1874 Rather than timing out after 20 ms if an EC
1875 command is not properly ACKed, override the length
1876 of the timeout. We have interrupts disabled while
1877 waiting for the ACK, so if this is set too high
1878 interrupts *may* be lost!
1880 omap_mux= [OMAP] Override bootloader pin multiplexing.
1881 Format: <mux_mode0.mode_name=value>...
1882 For example, to override I2C bus2:
1883 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1885 oprofile.timer= [HW]
1886 Use timer interrupt instead of performance counters
1888 oprofile.cpu_type= Force an oprofile cpu type
1889 This might be useful if you have an older oprofile
1890 userland or if you want common events.
1891 Format: { arch_perfmon }
1892 arch_perfmon: [X86] Force use of architectural
1893 perfmon on Intel CPUs instead of the
1894 CPU specific event set.
1896 oops=panic Always panic on oopses. Default is to just kill the
1897 process, but there is a small probability of
1898 deadlocking the machine.
1899 This will also cause panics on machine check exceptions.
1900 Useful together with panic=30 to trigger a reboot.
1903 See Documentation/sound/oss/oss-parameters.txt
1905 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1906 timeout > 0: seconds before rebooting
1907 timeout = 0: wait forever
1908 timeout < 0: reboot immediately
1911 parkbd.port= [HW] Parallel port number the keyboard adapter is
1912 connected to, default is 0.
1914 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1915 0 for XT, 1 for AT (default is AT).
1918 parport= [HW,PPT] Specify parallel ports. 0 disables.
1919 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1920 Use 'auto' to force the driver to use any
1921 IRQ/DMA settings detected (the default is to
1922 ignore detected IRQ/DMA settings because of
1923 possible conflicts). You can specify the base
1924 address, IRQ, and DMA settings; IRQ and DMA
1925 should be numbers, or 'auto' (for using detected
1926 settings on that particular port), or 'nofifo'
1927 (to avoid using a FIFO even if it is detected).
1928 Parallel ports are assigned in the order they
1929 are specified on the command line, starting
1932 parport_init_mode= [HW,PPT]
1933 Configure VIA parallel port to operate in
1934 a specific mode. This is necessary on Pegasos
1935 computer where firmware has no options for setting
1936 up parallel port mode and sets it to spp.
1937 Currently this function knows 686a and 8231 chips.
1938 Format: [spp|ps2|epp|ecp|ecpepp]
1941 Halt all CPUs after the first oops has been printed for
1942 the specified number of seconds. This is to be used if
1943 your oopses keep scrolling off the screen.
1948 See header of drivers/block/paride/pcd.c.
1949 See also Documentation/blockdev/paride.txt.
1951 pci=option[,option...] [PCI] various PCI subsystem options:
1952 earlydump [X86] dump PCI config space before the kernel
1954 off [X86] don't probe for the PCI bus
1955 bios [X86-32] force use of PCI BIOS, don't access
1956 the hardware directly. Use this if your machine
1957 has a non-standard PCI host bridge.
1958 nobios [X86-32] disallow use of PCI BIOS, only direct
1959 hardware access methods are allowed. Use this
1960 if you experience crashes upon bootup and you
1961 suspect they are caused by the BIOS.
1962 conf1 [X86] Force use of PCI Configuration
1964 conf2 [X86] Force use of PCI Configuration
1966 noaer [PCIE] If the PCIEAER kernel config parameter is
1967 enabled, this kernel boot option can be used to
1968 disable the use of PCIE advanced error reporting.
1969 nodomains [PCI] Disable support for multiple PCI
1970 root domains (aka PCI segments, in ACPI-speak).
1971 nommconf [X86] Disable use of MMCONFIG for PCI
1973 check_enable_amd_mmconf [X86] check for and enable
1974 properly configured MMIO access to PCI
1975 config space on AMD family 10h CPU
1976 nomsi [MSI] If the PCI_MSI kernel config parameter is
1977 enabled, this kernel boot option can be used to
1978 disable the use of MSI interrupts system-wide.
1979 noioapicquirk [APIC] Disable all boot interrupt quirks.
1980 Safety option to keep boot IRQs enabled. This
1981 should never be necessary.
1982 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1983 primary IO-APIC for bridges that cannot disable
1984 boot IRQs. This fixes a source of spurious IRQs
1985 when the system masks IRQs.
1986 noioapicreroute [APIC] Disable workaround that uses the
1987 boot IRQ equivalent of an IRQ that connects to
1988 a chipset where boot IRQs cannot be disabled.
1989 The opposite of ioapicreroute.
1990 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1991 routing table. These calls are known to be buggy
1992 on several machines and they hang the machine
1993 when used, but on other computers it's the only
1994 way to get the interrupt routing table. Try
1995 this option if the kernel is unable to allocate
1996 IRQs or discover secondary PCI buses on your
1998 rom [X86] Assign address space to expansion ROMs.
1999 Use with caution as certain devices share
2000 address decoders between ROMs and other
2002 norom [X86] Do not assign address space to
2003 expansion ROMs that do not already have
2004 BIOS assigned address ranges.
2005 nobar [X86] Do not assign address space to the
2006 BARs that weren't assigned by the BIOS.
2007 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2008 assigned automatically to PCI devices. You can
2009 make the kernel exclude IRQs of your ISA cards
2011 pirqaddr=0xAAAAA [X86] Specify the physical address
2012 of the PIRQ table (normally generated
2013 by the BIOS) if it is outside the
2014 F0000h-100000h range.
2015 lastbus=N [X86] Scan all buses thru bus #N. Can be
2016 useful if the kernel is unable to find your
2017 secondary buses and you want to tell it
2018 explicitly which ones they are.
2019 assign-busses [X86] Always assign all PCI bus
2020 numbers ourselves, overriding
2021 whatever the firmware may have done.
2022 usepirqmask [X86] Honor the possible IRQ mask stored
2023 in the BIOS $PIR table. This is needed on
2024 some systems with broken BIOSes, notably
2025 some HP Pavilion N5400 and Omnibook XE3
2026 notebooks. This will have no effect if ACPI
2027 IRQ routing is enabled.
2028 noacpi [X86] Do not use ACPI for IRQ routing
2029 or for PCI scanning.
2030 use_crs [X86] Use PCI host bridge window information
2031 from ACPI. On BIOSes from 2008 or later, this
2032 is enabled by default. If you need to use this,
2033 please report a bug.
2034 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2035 If you need to use this, please report a bug.
2036 routeirq Do IRQ routing for all PCI devices.
2037 This is normally done in pci_enable_device(),
2038 so this option is a temporary workaround
2039 for broken drivers that don't call it.
2040 skip_isa_align [X86] do not align io start addr, so can
2041 handle more pci cards
2042 firmware [ARM] Do not re-enumerate the bus but instead
2043 just use the configuration from the
2044 bootloader. This is currently used on
2045 IXP2000 systems where the bus has to be
2046 configured a certain way for adjunct CPUs.
2047 noearly [X86] Don't do any early type 1 scanning.
2048 This might help on some broken boards which
2049 machine check when some devices' config space
2050 is read. But various workarounds are disabled
2051 and some IOMMU drivers will not work.
2052 bfsort Sort PCI devices into breadth-first order.
2053 This sorting is done to get a device
2054 order compatible with older (<= 2.4) kernels.
2055 nobfsort Don't sort PCI devices into breadth-first order.
2056 cbiosize=nn[KMG] The fixed amount of bus space which is
2057 reserved for the CardBus bridge's IO window.
2058 The default value is 256 bytes.
2059 cbmemsize=nn[KMG] The fixed amount of bus space which is
2060 reserved for the CardBus bridge's memory
2061 window. The default value is 64 megabytes.
2064 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2065 Specifies alignment and device to reassign
2066 aligned memory resources.
2067 If <order of align> is not specified,
2068 PAGE_SIZE is used as alignment.
2069 PCI-PCI bridge can be specified, if resource
2070 windows need to be expanded.
2071 ecrc= Enable/disable PCIe ECRC (transaction layer
2072 end-to-end CRC checking).
2073 bios: Use BIOS/firmware settings. This is the
2077 realloc reallocate PCI resources if allocations done by BIOS
2080 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2083 force Enable ASPM even on devices that claim not to support it.
2084 WARNING: Forcing ASPM on may cause system lockups.
2086 pcie_ports= [PCIE] PCIe ports handling:
2087 auto Ask the BIOS whether or not to use native PCIe services
2088 associated with PCIe ports (PME, hot-plug, AER). Use
2089 them only if that is allowed by the BIOS.
2090 native Use native PCIe services associated with PCIe ports
2092 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2095 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2096 nomsi Do not use MSI for native PCIe PME signaling (this makes
2097 all PCIe root ports use INTx for all services).
2099 pcmv= [HW,PCMCIA] BadgePAD 4
2102 See Documentation/blockdev/paride.txt.
2104 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2107 See arch/parisc/kernel/pdc_chassis.c
2109 percpu_alloc= Select which percpu first chunk allocator to use.
2110 Currently supported values are "embed" and "page".
2111 Archs may support subset or none of the selections.
2112 See comments in mm/percpu.c for details on each
2113 allocator. This parameter is primarily for debugging
2114 and performance comparison.
2117 See Documentation/blockdev/paride.txt.
2120 See Documentation/blockdev/paride.txt.
2122 pirq= [SMP,APIC] Manual mp-table setup
2123 See Documentation/x86/i386/IO-APIC.txt.
2125 plip= [PPT,NET] Parallel port network link
2126 Format: { parport<nr> | timid | 0 }
2127 See also Documentation/parport.txt.
2129 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2130 Override pmtimer IOPort with a hex value.
2134 Enable PNP debug messages (depends on the
2135 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2136 via /sys/module/pnp/parameters/debug. We always show
2137 current resource usage; turning this on also shows
2138 possible settings and some assignment information.
2144 { on | off | curr | res | no-curr | no-res }
2147 [ISAPNP] Exclude IRQs for the autoconfiguration
2150 [ISAPNP] Exclude DMAs for the autoconfiguration
2152 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2153 Ranges are in pairs (I/O port base and size).
2156 [ISAPNP] Exclude memory regions for the
2158 Ranges are in pairs (memory base and size).
2160 ports= [IP_VS_FTP] IPVS ftp helper module
2162 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2164 Format: <port>,<port>....
2166 print-fatal-signals=
2167 [KNL] debug: print fatal signals
2169 If enabled, warn about various signal handling
2170 related application anomalies: too many signals,
2171 too many POSIX.1 timers, fatal signals causing a
2174 If you hit the warning due to signal overflow,
2175 you might want to try "ulimit -i unlimited".
2179 printk.time= Show timing data prefixed to each printk message line
2180 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2182 processor.max_cstate= [HW,ACPI]
2183 Limit processor to maximum C-state
2184 max_cstate=9 overrides any DMI blacklist limit.
2186 processor.nocst [HW,ACPI]
2187 Ignore the _CST method to determine C-states,
2188 instead using the legacy FADT method
2190 profile= [KNL] Enable kernel profiling via /proc/profile
2191 Format: [schedule,]<number>
2192 Param: "schedule" - profile schedule points.
2193 Param: <number> - step/bucket size as a power of 2 for
2194 statistical time based profiling.
2195 Param: "sleep" - profile D-state sleeping (millisecs).
2196 Requires CONFIG_SCHEDSTATS
2197 Param: "kvm" - profile VM exits.
2199 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2201 See Documentation/blockdev/ramdisk.txt.
2203 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2204 probe for; one of (bare|imps|exps|lifebook|any).
2205 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2207 psmouse.resetafter= [HW,MOUSE]
2208 Try to reset the device after so many bad packets
2211 [HW,MOUSE] Set desired mouse resolution, in dpi.
2212 psmouse.smartscroll=
2213 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2214 0 = disabled, 1 = enabled (default).
2216 pstore.backend= Specify the name of the pstore backend to use
2219 See Documentation/blockdev/paride.txt.
2222 [KNL] Number of legacy pty's. Overwrites compiled-in
2225 quiet [KNL] Disable most log messages
2230 See Documentation/md.txt.
2232 ramdisk_blocksize= [RAM]
2233 See Documentation/blockdev/ramdisk.txt.
2235 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2236 See Documentation/blockdev/ramdisk.txt.
2238 rcupdate.blimit= [KNL,BOOT]
2239 Set maximum number of finished RCU callbacks to process
2242 rcupdate.qhimark= [KNL,BOOT]
2243 Set threshold of queued
2244 RCU callbacks over which batch limiting is disabled.
2246 rcupdate.qlowmark= [KNL,BOOT]
2247 Set threshold of queued RCU callbacks below which
2248 batch limiting is re-enabled.
2252 Run specified binary instead of /init from the ramdisk,
2253 used for early userspace startup. See initrd.
2255 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2256 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2257 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2260 [KNL, SMP] Set scheduler's default relax_domain_level.
2261 See Documentation/cgroups/cpusets.txt.
2263 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2265 reservetop= [X86-32]
2267 Reserves a hole at the top of the kernel virtual
2272 Set the amount of memory to reserve for BIOS at
2273 the bottom of the address space.
2275 reset_devices [KNL] Force drivers to reset the underlying device
2276 during initialization.
2279 Specify the partition device for software suspend
2281 resume_offset= [SWSUSP]
2282 Specify the offset from the beginning of the partition
2283 given by "resume=" at which the swap header is located,
2284 in <PAGE_SIZE> units (needed only for swap files).
2285 See Documentation/power/swsusp-and-swap-files.txt
2287 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2288 read the resume files
2290 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2291 Useful for devices that are detected asynchronously
2292 (e.g. USB and MMC devices).
2294 hibernate= [HIBERNATION]
2295 noresume Don't check if there's a hibernation image
2296 present during boot.
2297 nocompress Don't compress/decompress hibernation images.
2299 retain_initrd [RAM] Keep initrd memory after extraction
2301 rhash_entries= [KNL,NET]
2302 Set number of hash buckets for route cache
2304 riscom8= [HW,SERIAL]
2305 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2307 ro [KNL] Mount root device read-only on boot
2309 root= [KNL] Root filesystem
2310 See name_to_dev_t comment in init/do_mounts.c.
2312 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2313 mount the root filesystem
2315 rootflags= [KNL] Set root filesystem mount option string
2317 rootfstype= [KNL] Set root filesystem type
2319 rootwait [KNL] Wait (indefinitely) for root device to show up.
2320 Useful for devices that are detected asynchronously
2321 (e.g. USB and MMC devices).
2323 rw [KNL] Mount root device read-write on boot
2325 S [KNL] Run init in single mode
2328 See drivers/net/irda/sa1100_ir.c.
2330 sbni= [NET] Granch SBNI12 leased line adapter
2332 sched_debug [KNL] Enables verbose scheduler debug messages.
2334 security= [SECURITY] Choose a security module to enable at boot.
2335 If this boot parameter is not specified, only the first
2336 security module asking for security registration will be
2337 loaded. An invalid security module name will be treated
2338 as if no module has been chosen.
2340 selinux= [SELINUX] Disable or enable SELinux at boot time.
2341 Format: { "0" | "1" }
2342 See security/selinux/Kconfig help text.
2345 Default value is set via kernel config option.
2346 If enabled at boot time, /selinux/disable can be used
2347 later to disable prior to initial policy load.
2349 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2350 Format: { "0" | "1" }
2351 See security/apparmor/Kconfig help text
2354 Default value is set via kernel config option.
2356 serialnumber [BUGS=X86-32]
2359 Maximal number of shapers.
2361 show_msr= [x86] show boot-time MSR settings
2362 Format: { <integer> }
2363 Show boot-time (BIOS-initialized) MSR settings.
2364 The parameter means the number of CPUs to show,
2365 for example 1 means boot CPU only.
2372 slub_debug[=options[,slabs]] [MM, SLUB]
2373 Enabling slub_debug allows one to determine the
2374 culprit if slab objects become corrupted. Enabling
2375 slub_debug can create guard zones around objects and
2376 may poison objects when not in use. Also tracks the
2377 last alloc / free. For more information see
2378 Documentation/vm/slub.txt.
2380 slub_max_order= [MM, SLUB]
2381 Determines the maximum allowed order for slabs.
2382 A high setting may cause OOMs due to memory
2383 fragmentation. For more information see
2384 Documentation/vm/slub.txt.
2386 slub_min_objects= [MM, SLUB]
2387 The minimum number of objects per slab. SLUB will
2388 increase the slab order up to slub_max_order to
2389 generate a sufficiently large slab able to contain
2390 the number of objects indicated. The higher the number
2391 of objects the smaller the overhead of tracking slabs
2392 and the less frequently locks need to be acquired.
2393 For more information see Documentation/vm/slub.txt.
2395 slub_min_order= [MM, SLUB]
2396 Determines the mininum page order for slabs. Must be
2397 lower than slub_max_order.
2398 For more information see Documentation/vm/slub.txt.
2400 slub_nomerge [MM, SLUB]
2401 Disable merging of slabs with similar size. May be
2402 necessary if there is some reason to distinguish
2403 allocs to different slabs. Debug options disable
2404 merging on their own.
2405 For more information see Documentation/vm/slub.txt.
2408 Format: <io1>[,<io2>[,...,<io8>]]
2410 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2411 attempt to substitute SMP alternatives once at boot.
2413 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2414 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2415 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2416 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2417 smsc-ircc2.ircc_irq= [HW] IRQ line
2418 smsc-ircc2.ircc_dma= [HW] DMA channel
2419 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2420 0: Toshiba Satellite 1800 (GP data pin select)
2421 1: Fast pin select (default)
2425 [KNL] Should the soft-lockup detector generate panics.
2428 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2429 See Documentation/laptops/sonypi.txt
2431 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2432 See Documentation/serial/specialix.txt.
2434 spia_io_base= [HW,MTD]
2440 Enabled the stack tracer on boot up.
2444 Set the STI (builtin display/keyboard on the HP-PARISC
2445 machines) console (graphic card) which should be used
2446 as the initial boot-console.
2447 See also comment in drivers/video/console/sticore.c.
2450 See comment in drivers/video/console/sticore.c.
2453 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2455 sunrpc.min_resvport=
2456 sunrpc.max_resvport=
2458 SunRPC servers often require that client requests
2459 originate from a privileged port (i.e. a port in the
2460 range 0 < portnr < 1024).
2461 An administrator who wishes to reserve some of these
2462 ports for other uses may adjust the range that the
2463 kernel's sunrpc client considers to be privileged
2464 using these two parameters to set the minimum and
2465 maximum port values.
2469 Control how the NFS server code allocates CPUs to
2470 service thread pools. Depending on how many NICs
2471 you have and where their interrupts are bound, this
2472 option will affect which CPUs will do NFS serving.
2473 Note: this parameter cannot be changed while the
2474 NFS server is running.
2476 auto the server chooses an appropriate mode
2477 automatically using heuristics
2478 global a single global pool contains all CPUs
2479 percpu one pool for each CPU
2480 pernode one pool for each NUMA node (equivalent
2481 to global on non-NUMA machines)
2483 sunrpc.tcp_slot_table_entries=
2484 sunrpc.udp_slot_table_entries=
2486 Sets the upper limit on the number of simultaneous
2487 RPC calls that can be sent from the client to a
2488 server. Increasing these values may allow you to
2489 improve throughput, but will also increase the
2490 amount of memory reserved for use by the client.
2493 [KNL] Enable accounting of swap in memory resource
2494 controller if no parameter or 1 is given or disable
2495 it if 0 is given (See Documentation/cgroups/memory.txt)
2497 swiotlb= [IA-64] Number of I/O TLB slabs
2501 sysfs.deprecated=0|1 [KNL]
2502 Enable/disable old style sysfs layout for old udev
2503 on older distributions. When this option is enabled
2504 very new udev will not work anymore. When this option
2505 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2506 in older udev will not work anymore.
2507 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2508 the kernel configuration.
2510 sysrq_always_enabled
2512 Ignore sysrq setting - this boot parameter will
2513 neutralize any effect of /proc/sys/kernel/sysrq.
2514 Useful for debugging.
2518 test_suspend= [SUSPEND]
2519 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2520 standby suspend) as the system sleep state to briefly
2521 enter during system startup. The system is woken from
2522 this state using a wakeup-capable RTC alarm.
2524 thash_entries= [KNL,NET]
2525 Set number of hash buckets for TCP connection
2527 thermal.act= [HW,ACPI]
2528 -1: disable all active trip points in all thermal zones
2529 <degrees C>: override all lowest active trip points
2531 thermal.crt= [HW,ACPI]
2532 -1: disable all critical trip points in all thermal zones
2533 <degrees C>: override all critical trip points
2535 thermal.nocrt= [HW,ACPI]
2536 Set to disable actions on ACPI thermal zone
2537 critical and hot trip points.
2539 thermal.off= [HW,ACPI]
2540 1: disable ACPI thermal control
2542 thermal.psv= [HW,ACPI]
2543 -1: disable all passive trip points
2544 <degrees C>: override all passive trip points to this
2547 thermal.tzp= [HW,ACPI]
2548 Specify global default ACPI thermal zone polling rate
2549 <deci-seconds>: poll all this frequency
2550 0: no polling (default)
2553 Force threading of all interrupt handlers except those
2554 marked explicitely IRQF_NO_THREAD.
2558 Specify if the kernel should make use of the cpu
2559 topology information if the hardware supports this.
2560 The scheduler will make use of this information and
2561 e.g. base its process migration decisions on it.
2566 tpm_suspend_pcr=[HW,TPM]
2567 Format: integer pcr id
2568 Specify that at suspend time, the tpm driver
2569 should extend the specified pcr with zeros,
2570 as a workaround for some chips which fail to
2571 flush the last written pcr on TPM_SaveState.
2572 This will guarantee that all the other pcrs
2575 trace_buf_size=nn[KMG]
2576 [FTRACE] will set tracing buffer size.
2578 trace_event=[event-list]
2579 [FTRACE] Set and start specified trace events in order
2580 to facilitate early boot debugging.
2581 See also Documentation/trace/events.txt
2583 tsc= Disable clocksource stability checks for TSC.
2585 [x86] reliable: mark tsc clocksource as reliable, this
2586 disables clocksource verification at runtime, as well
2587 as the stability checks done at bootup. Used to enable
2588 high-resolution timer mode on older hardware, and in
2589 virtualized environment.
2590 [x86] noirqtime: Do not use TSC to do irq accounting.
2591 Used to run time disable IRQ_TIME_ACCOUNTING on any
2592 platforms where RDTSC is slow and this accounting
2595 turbografx.map[2|3]= [HW,JOY]
2596 TurboGraFX parallel port interface
2598 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2599 See also Documentation/input/joystick-parport.txt
2601 udbg-immortal [PPC] When debugging early kernel crashes that
2602 happen after console_init() and before a proper
2603 console driver takes over, this boot options might
2604 help "seeing" what's going on.
2606 uhash_entries= [KNL,NET]
2607 Set number of hash buckets for UDP/UDP-Lite connections
2610 [USB] Ignore overcurrent events (default N).
2611 Some badly-designed motherboards generate lots of
2612 bogus events, for ports that aren't wired to
2613 anything. Set this parameter to avoid log spamming.
2614 Note that genuine overcurrent events won't be
2618 [X86] Cause panic on unknown NMI.
2620 usbcore.authorized_default=
2621 [USB] Default USB device authorization:
2622 (default -1 = authorized except for wireless USB,
2623 0 = not authorized, 1 = authorized)
2625 usbcore.autosuspend=
2626 [USB] The autosuspend time delay (in seconds) used
2627 for newly-detected USB devices (default 2). This
2628 is the time required before an idle device will be
2629 autosuspended. Devices for which the delay is set
2630 to a negative value won't be autosuspended at all.
2632 usbcore.usbfs_snoop=
2633 [USB] Set to log all usbfs traffic (default 0 = off).
2635 usbcore.blinkenlights=
2636 [USB] Set to cycle leds on hubs (default 0 = off).
2638 usbcore.old_scheme_first=
2639 [USB] Start with the old device initialization
2640 scheme (default 0 = off).
2642 usbcore.use_both_schemes=
2643 [USB] Try the other device initialization scheme
2644 if the first one fails (default 1 = enabled).
2646 usbcore.initial_descriptor_timeout=
2647 [USB] Specifies timeout for the initial 64-byte
2648 USB_REQ_GET_DESCRIPTOR request in milliseconds
2649 (default 5000 = 5.0 seconds).
2652 [USBHID] The interval which mice are to be polled at.
2654 usb-storage.delay_use=
2655 [UMS] The delay in seconds before a new device is
2656 scanned for Logical Units (default 5).
2659 [UMS] A list of quirks entries to supplement or
2660 override the built-in unusual_devs list. List
2661 entries are separated by commas. Each entry has
2662 the form VID:PID:Flags where VID and PID are Vendor
2663 and Product ID values (4-digit hex numbers) and
2664 Flags is a set of characters, each corresponding
2665 to a common usb-storage quirk flag as follows:
2666 a = SANE_SENSE (collect more than 18 bytes
2668 b = BAD_SENSE (don't collect more than 18
2669 bytes of sense data);
2670 c = FIX_CAPACITY (decrease the reported
2671 device capacity by one sector);
2672 d = NO_READ_DISC_INFO (don't use
2673 READ_DISC_INFO command);
2674 e = NO_READ_CAPACITY_16 (don't use
2675 READ_CAPACITY_16 command);
2676 h = CAPACITY_HEURISTICS (decrease the
2677 reported device capacity by one
2678 sector if the number is odd);
2679 i = IGNORE_DEVICE (don't bind to this
2681 l = NOT_LOCKABLE (don't try to lock and
2682 unlock ejectable media);
2683 m = MAX_SECTORS_64 (don't transfer more
2684 than 64 sectors = 32 KB at a time);
2685 n = INITIAL_READ10 (force a retry of the
2686 initial READ(10) command);
2687 o = CAPACITY_OK (accept the capacity
2688 reported by the device);
2689 r = IGNORE_RESIDUE (the device reports
2690 bogus residue values);
2691 s = SINGLE_LUN (the device has only one
2693 w = NO_WP_DETECT (don't test whether the
2694 medium is write-protected).
2695 Example: quirks=0419:aaf5:rl,0421:0433:rc
2697 user_debug= [KNL,ARM]
2699 See arch/arm/Kconfig.debug help text.
2700 1 - undefined instruction events
2702 4 - invalid data aborts
2705 Example: user_debug=31
2708 [X86] Flags controlling user PTE allocations.
2710 nohigh = do not allocate PTE pages in
2711 HIGHMEM regardless of setting
2715 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2716 vdso=1: enable VDSO (default)
2717 vdso=0: disable VDSO mapping
2720 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2721 vdso32=1: enable 32-bit VDSO (default)
2722 vdso32=0: disable 32-bit VDSO mapping
2725 vector=percpu: enable percpu vector domain
2727 video= [FB] Frame buffer configuration
2728 See Documentation/fb/modedb.txt.
2730 vga= [BOOT,X86-32] Select a particular video mode
2731 See Documentation/x86/boot.txt and
2732 Documentation/svga.txt.
2733 Use vga=ask for menu.
2734 This is actually a boot loader parameter; the value is
2735 passed to the kernel using a special protocol.
2737 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2738 size of <nn>. This can be used to increase the
2739 minimum size (128MB on x86). It can also be used to
2740 decrease the size and leave more room for directly
2743 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2746 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2749 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2753 Controls the behavior of vsyscalls (i.e. calls to
2754 fixed addresses of 0xffffffffff600x00 from legacy
2755 code). Most statically-linked binaries and older
2756 versions of glibc use these calls. Because these
2757 functions are at fixed addresses, they make nice
2758 targets for exploits that can control RIP.
2760 emulate Vsyscalls turn into traps and are emulated
2763 native [default] Vsyscalls are native syscall
2765 This is a little bit faster than trapping
2766 and makes a few dynamic recompilers work
2767 better than they would in emulation mode.
2768 It also makes exploits much easier to write.
2770 none Vsyscalls don't work at all. This makes
2771 them quite hard to use for exploits but
2772 might break your system.
2774 vt.cur_default= [VT] Default cursor shape.
2775 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2776 the parameters of the <Esc>[?A;B;Cc escape sequence;
2777 see VGA-softcursor.txt. Default: 2 = underline.
2779 vt.default_blu= [VT]
2780 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2781 Change the default blue palette of the console.
2782 This is a 16-member array composed of values
2785 vt.default_grn= [VT]
2786 Format: <green0>,<green1>,<green2>,...,<green15>
2787 Change the default green palette of the console.
2788 This is a 16-member array composed of values
2791 vt.default_red= [VT]
2792 Format: <red0>,<red1>,<red2>,...,<red15>
2793 Change the default red palette of the console.
2794 This is a 16-member array composed of values
2800 Set system-wide default UTF-8 mode for all tty's.
2801 Default is 1, i.e. UTF-8 mode is enabled for all
2802 newly opened terminals.
2804 vt.global_cursor_default=
2807 Set system-wide default for whether a cursor
2808 is shown on new VTs. Default is -1,
2809 i.e. cursors will be created by default unless
2810 overridden by individual drivers. 0 will hide
2811 cursors, 1 will display them.
2813 watchdog timers [HW,WDT] For information on watchdog timers,
2814 see Documentation/watchdog/watchdog-parameters.txt
2815 or other driver-specific files in the
2816 Documentation/watchdog/ directory.
2818 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2819 default x2apic cluster mode on platforms
2822 x86_mrst_timer= [X86-32,APBT]
2823 Choose timer option for x86 Moorestown MID platform.
2824 Two valid options are apbt timer only and lapic timer
2825 plus one apbt timer for broadcast timer.
2826 x86_mrst_timer=apbt_only | lapic_and_apbt
2828 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2829 xd_geo= See header of drivers/block/xd.c.
2831 xen_emul_unplug= [HW,X86,XEN]
2832 Unplug Xen emulated devices
2833 Format: [unplug0,][unplug1]
2834 ide-disks -- unplug primary master IDE devices
2835 aux-ide-disks -- unplug non-primary-master IDE devices
2836 nics -- unplug network devices
2837 all -- unplug all emulated devices (NICs and IDE disks)
2838 unnecessary -- unplugging emulated devices is
2839 unnecessary even if the host did not respond to
2841 never -- do not unplug even if version check succeeds
2843 xirc2ps_cs= [NET,PCMCIA]
2845 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2847 ______________________________________________________________________
2851 Add more DRM drivers.
projects / ~andy / linux / blob