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 MDA MDA console support is enabled.
74 MIPS MIPS architecture is enabled.
75 MOUSE Appropriate mouse support is enabled.
76 MSI Message Signaled Interrupts (PCI).
77 MTD MTD (Memory Technology Device) support is enabled.
78 NET Appropriate network support is enabled.
79 NUMA NUMA support is enabled.
80 NFS Appropriate NFS support is enabled.
81 OSS OSS sound support is enabled.
82 PV_OPS A paravirtualized kernel is enabled.
83 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
84 PARISC The PA-RISC architecture is enabled.
85 PCI PCI bus support is enabled.
86 PCIE PCI Express support is enabled.
87 PCMCIA The PCMCIA subsystem is enabled.
88 PNP Plug & Play support is enabled.
89 PPC PowerPC architecture is enabled.
90 PPT Parallel port support is enabled.
91 PS2 Appropriate PS/2 support is enabled.
92 RAM RAM disk support is enabled.
93 S390 S390 architecture is enabled.
94 SCSI Appropriate SCSI support is enabled.
95 A lot of drivers have their options described inside
96 the Documentation/scsi/ sub-directory.
97 SECURITY Different security models are enabled.
98 SELINUX SELinux support is enabled.
99 APPARMOR AppArmor support is enabled.
100 SERIAL Serial support is enabled.
101 SH SuperH architecture is enabled.
102 SMP The kernel is an SMP kernel.
103 SPARC Sparc architecture is enabled.
104 SWSUSP Software suspend (hibernation) is enabled.
105 SUSPEND System suspend states are enabled.
106 TPM TPM drivers are enabled.
107 TS Appropriate touchscreen support is enabled.
108 UMS USB Mass Storage support is enabled.
109 USB USB support is enabled.
110 USBHID USB Human Interface Device support is enabled.
111 V4L Video For Linux support is enabled.
112 VMMIO Driver for memory mapped virtio devices 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
613 details. Deprecated, see dyndbg.
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 debug_guardpage_minorder=
632 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
633 parameter allows control of the order of pages that will
634 be intentionally kept free (and hence protected) by the
635 buddy allocator. Bigger value increase the probability
636 of catching random memory corruption, but reduce the
637 amount of memory for normal system use. The maximum
638 possible value is MAX_ORDER/2. Setting this parameter
639 to 1 or 2 should be enough to identify most random
640 memory corruption problems caused by bugs in kernel or
641 driver code when a CPU writes to (or reads from) a
642 random memory location. Note that there exists a class
643 of memory corruptions problems caused by buggy H/W or
644 F/W or by drivers badly programing DMA (basically when
645 memory is written at bus level and the CPU MMU is
646 bypassed) which are not detectable by
647 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
648 tracking down these problems.
650 debugpat [X86] Enable PAT debugging
652 decnet.addr= [HW,NET]
653 Format: <area>[,<node>]
654 See also Documentation/networking/decnet.txt.
657 [same as hugepagesz=] The size of the default
658 HugeTLB page size. This is the size represented by
659 the legacy /proc/ hugepages APIs, used for SHM, and
660 default size when mounting hugetlbfs filesystems.
661 Defaults to the default architecture's huge page size
665 Set number of hash buckets for dentry cache.
668 IO parameters + enable/disable command.
670 digiepca= [HW,SERIAL]
671 See drivers/char/README.epca and
672 Documentation/serial/digiepca.txt.
675 See Documentation/networking/ipv6.txt.
677 disable_ddw [PPC/PSERIES]
678 Disable Dynamic DMA Window support. Use this if
679 to workaround buggy firmware.
682 See Documentation/networking/ipv6.txt.
684 disable_mtrr_cleanup [X86]
685 The kernel tries to adjust MTRR layout from continuous
686 to discrete, to make X server driver able to add WB
687 entry later. This parameter disables that.
689 disable_mtrr_trim [X86, Intel and AMD only]
690 By default the kernel will trim any uncacheable
691 memory out of your available memory pool based on
692 MTRR settings. This parameter disables that behavior,
693 possibly causing your machine to run very slowly.
695 disable_timer_pin_1 [X86]
696 Disable PIN 1 of APIC timer
697 Can be useful to work around chipset bugs.
699 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
700 this option disables the debugging code at boot.
702 dma_debug_entries=<number>
703 This option allows to tune the number of preallocated
704 entries for DMA-API debugging code. One entry is
705 required per DMA-API allocation. Use this if the
706 DMA-API debugging code disables itself because the
707 architectural default is too low.
709 dma_debug_driver=<driver_name>
710 With this option the DMA-API debugging driver
711 filter feature can be enabled at boot time. Just
712 pass the driver to filter for as the parameter.
713 The filter can be disabled or changed to another
714 driver later using sysfs.
716 drm_kms_helper.edid_firmware=[<connector>:]<file>
717 Broken monitors, graphic adapters and KVMs may
718 send no or incorrect EDID data sets. This parameter
719 allows to specify an EDID data set in the
720 /lib/firmware directory that is used instead.
721 Generic built-in EDID data sets are used, if one of
722 edid/1024x768.bin, edid/1280x1024.bin,
723 edid/1680x1050.bin, or edid/1920x1080.bin is given
724 and no file with the same name exists. Details and
725 instructions how to build your own EDID data are
726 available in Documentation/EDID/HOWTO.txt. An EDID
727 data set will only be used for a particular connector,
728 if its name and a colon are prepended to the EDID
733 dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
734 module.dyndbg[="val"]
735 Enable debug messages at boot time. See
736 Documentation/dynamic-debug-howto.txt for details.
738 earlycon= [KNL] Output early console device and options.
739 uart[8250],io,<addr>[,options]
740 uart[8250],mmio,<addr>[,options]
741 uart[8250],mmio32,<addr>[,options]
742 Start an early, polled-mode console on the 8250/16550
743 UART at the specified I/O port or MMIO address.
744 MMIO inter-register address stride is either 8-bit
745 (mmio) or 32-bit (mmio32).
746 The options are the same as for ttyS, above.
748 earlyprintk= [X86,SH,BLACKFIN]
750 earlyprintk=serial[,ttySn[,baudrate]]
751 earlyprintk=ttySn[,baudrate]
752 earlyprintk=dbgp[debugController#]
754 Append ",keep" to not disable it when the real console
757 Only vga or serial or usb debug port at a time.
759 Currently only ttyS0 and ttyS1 are supported.
761 Interaction with the standard serial driver is not
764 The VGA output is eventually overwritten by the real
767 ekgdboc= [X86,KGDB] Allow early kernel console debugging
770 This is designed to be used in conjunction with
771 the boot argument: earlyprintk=vga
774 Format: {"off" | "on" | "skip[mbr]"}
776 eisa_irq_edge= [PARISC,HW]
777 See header of drivers/parisc/eisa.c.
780 See comment before function elanfreq_setup() in
781 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
784 Format: {"cfq" | "deadline" | "noop"}
785 See Documentation/block/cfq-iosched.txt and
786 Documentation/block/deadline-iosched.txt for details.
788 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
789 Specifies physical address of start of kernel core
790 image elf header and optionally the size. Generally
791 kexec loader will pass this option to capture kernel.
792 See Documentation/kdump/kdump.txt for details.
794 enable_mtrr_cleanup [X86]
795 The kernel tries to adjust MTRR layout from continuous
796 to discrete, to make X server driver able to add WB
797 entry later. This parameter enables that.
799 enable_timer_pin_1 [X86]
800 Enable PIN 1 of APIC timer
801 Can be useful to work around chipset bugs
802 (in particular on some ATI chipsets).
803 The kernel tries to set a reasonable default.
805 enforcing [SELINUX] Set initial enforcing status.
807 See security/selinux/Kconfig help text.
808 0 -- permissive (log only, no denials).
809 1 -- enforcing (deny and log).
811 Value can be changed at runtime via /selinux/enforce.
814 Disable Error Record Serialization Table (ERST)
817 ether= [HW,NET] Ethernet cards parameters
818 This option is obsoleted by the "netdev=" option, which
819 has equivalent usage. See its documentation for details.
823 Permit 'security.evm' to be updated regardless of
824 current integrity status.
828 fail_make_request=[KNL]
829 General fault injection mechanism.
830 Format: <interval>,<probability>,<space>,<times>
831 See also Documentation/fault-injection/.
834 See Documentation/blockdev/floppy.txt.
836 force_pal_cache_flush
837 [IA-64] Avoid check_sal_cache_flush which may hang on
838 buggy SAL_CACHE_FLUSH implementations. Using this
839 parameter will force ia64_sal_cache_flush to call
840 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
843 [FTRACE] will set and start the specified tracer
844 as early as possible in order to facilitate early
847 ftrace_dump_on_oops[=orig_cpu]
848 [FTRACE] will dump the trace buffers on oops.
849 If no parameter is passed, ftrace will dump
850 buffers of all CPUs, but if you pass orig_cpu, it will
851 dump only the buffer of the CPU that triggered the
854 ftrace_filter=[function-list]
855 [FTRACE] Limit the functions traced by the function
856 tracer at boot up. function-list is a comma separated
857 list of functions. This list can be changed at run
858 time by the set_ftrace_filter file in the debugfs
861 ftrace_notrace=[function-list]
862 [FTRACE] Do not trace the functions specified in
863 function-list. This list can be changed at run time
864 by the set_ftrace_notrace file in the debugfs
867 ftrace_graph_filter=[function-list]
868 [FTRACE] Limit the top level callers functions traced
869 by the function graph tracer at boot up.
870 function-list is a comma separated list of functions
871 that can be changed at run time by the
872 set_graph_function file in the debugfs tracing directory.
875 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
876 support via parallel port (up to 5 devices per port)
877 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
878 See also Documentation/input/joystick-parport.txt
882 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
886 gcov_persist= [GCOV] When non-zero (default), profiling data for
887 kernel modules is saved and remains accessible via
888 debugfs, even when the module is unloaded/reloaded.
889 When zero, profiling data is discarded and associated
890 debugfs files are removed at module unload time.
892 gpt [EFI] Forces disk with valid GPT signature but
893 invalid Protective MBR to be treated as GPT.
895 hashdist= [KNL,NUMA] Large hashes allocated during boot
896 are distributed across NUMA nodes. Defaults on
897 for 64-bit NUMA, off otherwise.
898 Format: 0 | 1 (for off | on)
900 hcl= [IA-64] SGI's Hardware Graph compatibility layer
902 hd= [EIDE] (E)IDE hard drive subsystem geometry
903 Format: <cyl>,<head>,<sect>
906 Disable Hardware Error Source Table (HEST) support;
907 corresponding firmware-first mode error processing
908 logic will be disabled.
910 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
911 size of <nn>. This works even on boxes that have no
912 highmem otherwise. This also works to reduce highmem
913 size on bigger boxes.
915 highres= [KNL] Enable/disable high resolution timer mode.
916 Valid parameters: "on", "off"
920 See Documentation/isdn/README.HiSax.
924 hpet= [X86-32,HPET] option to control HPET usage
925 Format: { enable (default) | disable | force |
927 disable: disable HPET and use PIT instead
928 force: allow force enabled of undocumented chips (ICH4,
930 verbose: show contents of HPET registers during setup
932 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
933 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
934 On x86-64 and powerpc, this option can be specified
935 multiple times interleaved with hugepages= to reserve
936 huge pages of different sizes. Valid pages sizes on
937 x86-64 are 2M (when the CPU supports "pse") and 1G
938 (when the CPU supports the "pdpe1gb" cpuinfo flag)
939 Note that 1GB pages can only be allocated at boot time
940 using hugepages= and not freed afterwards.
942 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
943 terminal devices. Valid values: 0..8
944 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
945 If specified, z/VM IUCV HVC accepts connections
946 from listed z/VM user IDs only.
949 Do not unregister boot console at start. This is only
950 useful for debugging when something happens in the window
951 between unregistering the boot console and initializing
954 i2c_bus= [HW] Override the default board specific I2C bus speed
955 or register an additional I2C bus that is not
956 registered from board initialization code.
960 i8042.debug [HW] Toggle i8042 debug mode
961 i8042.direct [HW] Put keyboard port into non-translated mode
962 i8042.dumbkbd [HW] Pretend that controller can only read data from
963 keyboard and cannot control its state
964 (Don't attempt to blink the leds)
965 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
966 i8042.nokbd [HW] Don't check/create keyboard port
967 i8042.noloop [HW] Disable the AUX Loopback command while probing
969 i8042.nomux [HW] Don't check presence of an active multiplexing
971 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
973 i8042.notimeout [HW] Ignore timeout condition signalled by controller
974 i8042.reset [HW] Reset the controller during init and cleanup
975 i8042.unlock [HW] Unlock (ignore) the keylock
979 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
980 indicates that the driver is running on unsupported
982 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
983 does not match list of supported models.
985 [HW] Report power status in /proc/i8k
986 (disabled by default)
987 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
991 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
993 ide-core.nodma= [HW] (E)IDE subsystem
994 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
995 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
996 .cdrom .chs .ignore_cable are additional options
997 See Documentation/ide/ide.txt.
999 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1000 Claim all unknown PCI IDE storage controllers.
1003 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
1004 Poll forces a polling idle loop that can slightly
1005 improve the performance of waking up a idle CPU, but
1006 will use a lot of power and make the system run hot.
1008 idle=mwait: On systems which support MONITOR/MWAIT but
1009 the kernel chose to not use it because it doesn't save
1010 as much power as a normal idle loop, use the
1011 MONITOR/MWAIT idle loop anyways. Performance should be
1012 the same as idle=poll.
1013 idle=halt: Halt is forced to be used for CPU idle.
1014 In such case C2/C3 won't be used again.
1015 idle=nomwait: Disable mwait for CPU C-states
1017 ignore_loglevel [KNL]
1018 Ignore loglevel setting - this will print /all/
1019 kernel messages to the console. Useful for debugging.
1020 We also add it as printk module parameter, so users
1021 could change it dynamically, usually by
1022 /sys/module/printk/parameters/ignore_loglevel.
1024 ihash_entries= [KNL]
1025 Set number of hash buckets for inode cache.
1028 Format: { "0" | "1" }
1029 0 -- integrity auditing messages. (Default)
1030 1 -- enable informational integrity auditing messages.
1033 Format: { "sha1" | "md5" }
1037 Load a policy which meets the needs of the Trusted
1038 Computing Base. This means IMA will measure all
1039 programs exec'd, files mmap'd for exec, and all files
1040 opened for read by uid=0.
1044 Run specified binary instead of /sbin/init as init
1047 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1048 for working out where the kernel is dying during
1051 initrd= [BOOT] Specify the location of the initial ramdisk
1053 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1056 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1058 Enable intel iommu driver.
1060 Disable intel iommu driver.
1061 igfx_off [Default Off]
1062 By default, gfx is mapped as normal device. If a gfx
1063 device has a dedicated DMAR unit, the DMAR unit is
1064 bypassed by not enabling DMAR with this option. In
1065 this case, gfx device will use physical address for
1068 With this option iommu will not optimize to look
1069 for io virtual address below 32-bit forcing dual
1070 address cycle on pci bus for cards supporting greater
1071 than 32-bit addressing. The default is to look
1072 for translation below 32-bit and if not available
1073 then look in the higher range.
1074 strict [Default Off]
1075 With this option on every unmap_single operation will
1076 result in a hardware IOTLB flush operation as opposed
1077 to batching them for performance.
1078 sp_off [Default Off]
1079 By default, super page will be supported if Intel IOMMU
1080 has the capability. With this option, super page will
1083 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1084 0 disables intel_idle and fall back on acpi_idle.
1085 1 to 6 specify maximum depth of C-state.
1087 intremap= [X86-64, Intel-IOMMU]
1088 on enable Interrupt Remapping (default)
1089 off disable Interrupt Remapping
1090 nosid disable Source ID checking
1092 BIOS x2APIC opt-out request will be ignored
1094 iomem= Disable strict checking of access to MMIO memory
1095 strict regions from userspace.
1110 group_mf [x86, IA-64]
1113 io7= [HW] IO7 for Marvel based alpha systems
1114 See comment before marvel_specify_io7 in
1115 arch/alpha/kernel/core_marvel.c.
1117 io_delay= [X86] I/O delay method
1119 Standard port 0x80 based delay
1121 Alternate port 0xed based delay (needed on some systems)
1123 Simple two microseconds delay
1128 See Documentation/filesystems/nfs/nfsroot.txt.
1130 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1131 See comment before ip2_setup() in
1132 drivers/char/ip2/ip2base.c.
1135 When an interrupt is not handled search all handlers
1136 for it. Intended to get systems with badly broken
1140 When an interrupt is not handled search all handlers
1141 for it. Also check all handlers each timer
1142 interrupt. Intended to get systems with badly broken
1146 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1148 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1150 <cpu number>,...,<cpu number>
1152 <cpu number>-<cpu number>
1153 (must be a positive range in ascending order)
1155 <cpu number>,...,<cpu number>-<cpu number>
1157 This option can be used to specify one or more CPUs
1158 to isolate from the general SMP balancing and scheduling
1159 algorithms. You can move a process onto or off an
1160 "isolated" CPU via the CPU affinity syscalls or cpuset.
1161 <cpu number> begins at 0 and the maximum value is
1162 "number of CPUs in system - 1".
1164 This option is the preferred way to isolate CPUs. The
1165 alternative -- manually setting the CPU mask of all
1166 tasks in the system -- can cause problems and
1167 suboptimal load balancer performance.
1171 js= [HW,JOY] Analog joystick
1172 See Documentation/input/joystick.txt.
1176 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1177 specifies the amount of memory usable by the kernel
1178 for non-movable allocations. The requested amount is
1179 spread evenly throughout all nodes in the system. The
1180 remaining memory in each node is used for Movable
1181 pages. In the event, a node is too small to have both
1182 kernelcore and Movable pages, kernelcore pages will
1183 take priority and other nodes will have a larger number
1184 of kernelcore pages. The Movable zone is used for the
1185 allocation of pages that may be reclaimed or moved
1186 by the page migration subsystem. This means that
1187 HugeTLB pages may not be allocated from this zone.
1188 Note that allocations like PTEs-from-HighMem still
1189 use the HighMem zone if it exists, and the Normal
1190 zone if it does not.
1192 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1193 Format: <Controller#>[,poll interval]
1194 The controller # is the number of the ehci usb debug
1195 port as it is probed via PCI. The poll interval is
1196 optional and is the number seconds in between
1197 each poll cycle to the debug port in case you need
1198 the functionality for interrupting the kernel with
1199 gdb or control-c on the dbgp connection. When
1200 not using this parameter you use sysrq-g to break into
1201 the kernel debugger.
1203 kgdboc= [KGDB,HW] kgdb over consoles.
1204 Requires a tty driver that supports console polling,
1205 or a supported polling keyboard driver (non-usb).
1206 Serial only format: <serial_device>[,baud]
1207 keyboard only format: kbd
1208 keyboard and serial format: kbd,<serial_device>[,baud]
1209 Optional Kernel mode setting:
1210 kms, kbd format: kms,kbd
1211 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1213 kgdbwait [KGDB] Stop kernel execution and enter the
1214 kernel debugger at the earliest opportunity.
1216 kmac= [MIPS] korina ethernet MAC address.
1217 Configure the RouterBoard 532 series on-chip
1218 Ethernet adapter MAC address.
1220 kmemleak= [KNL] Boot-time kmemleak enable/disable
1221 Valid arguments: on, off
1224 kstack=N [X86] Print N words from the kernel stack
1227 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1228 Default is 0 (don't ignore, but inject #GP)
1230 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1234 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1235 Default is 1 (enabled)
1237 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1239 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1241 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1242 (virtualized MMU) support on capable Intel chips.
1243 Default is 1 (enabled)
1245 kvm-intel.emulate_invalid_guest_state=
1246 [KVM,Intel] Enable emulation of invalid guest states
1247 Default is 0 (disabled)
1249 kvm-intel.flexpriority=
1250 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1251 Default is 1 (enabled)
1254 [KVM,Intel] Enable VMX nesting (nVMX).
1255 Default is 0 (disabled)
1257 kvm-intel.unrestricted_guest=
1258 [KVM,Intel] Disable unrestricted guest feature
1259 (virtualized real and unpaged mode) on capable
1260 Intel chips. Default is 1 (enabled)
1262 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1263 feature (tagged TLBs) on capable Intel chips.
1264 Default is 1 (enabled)
1270 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1273 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1276 libata.dma= [LIBATA] DMA control
1277 libata.dma=0 Disable all PATA and SATA DMA
1278 libata.dma=1 PATA and SATA Disk DMA only
1279 libata.dma=2 ATAPI (CDROM) DMA only
1280 libata.dma=4 Compact Flash DMA only
1281 Combinations also work, so libata.dma=3 enables DMA
1282 for disks and CDROMs, but not CFs.
1284 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1285 libata.ignore_hpa=0 keep BIOS limits (default)
1286 libata.ignore_hpa=1 ignore limits, using full disk
1288 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1292 libata.force= [LIBATA] Force configurations. The format is comma
1293 separated list of "[ID:]VAL" where ID is
1294 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1295 matching port, link or device. Basically, it matches
1296 the ATA ID string printed on console by libata. If
1297 the whole ID part is omitted, the last PORT and DEVICE
1298 values are used. If ID hasn't been specified yet, the
1299 configuration applies to all ports, links and devices.
1301 If only DEVICE is omitted, the parameter applies to
1302 the port and all links and devices behind it. DEVICE
1303 number of 0 either selects the first device or the
1304 first fan-out link behind PMP device. It does not
1305 select the host link. DEVICE number of 15 selects the
1306 host link and device attached to it.
1308 The VAL specifies the configuration to force. As long
1309 as there's no ambiguity shortcut notation is allowed.
1310 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1311 The following configurations can be forced.
1313 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1314 Any ID with matching PORT is used.
1316 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1318 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1319 udma[/][16,25,33,44,66,100,133] notation is also
1322 * [no]ncq: Turn on or off NCQ.
1324 * nohrst, nosrst, norst: suppress hard, soft
1327 * dump_id: dump IDENTIFY data.
1329 If there are multiple matching configurations changing
1330 the same attribute, the last one is used.
1332 memblock=debug [KNL] Enable memblock debug messages.
1334 load_ramdisk= [RAM] List of ramdisks to load from floppy
1335 See Documentation/blockdev/ramdisk.txt.
1337 lockd.nlm_grace_period=P [NFS] Assign grace period.
1340 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1343 lockd.nlm_timeout=T [NFS] Assign timeout value.
1346 lockd.nlm_udpport=M [NFS] Assign UDP port.
1349 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1352 loglevel= All Kernel Messages with a loglevel smaller than the
1353 console loglevel will be printed to the console. It can
1354 also be changed with klogd or other programs. The
1355 loglevels are defined as follows:
1357 0 (KERN_EMERG) system is unusable
1358 1 (KERN_ALERT) action must be taken immediately
1359 2 (KERN_CRIT) critical conditions
1360 3 (KERN_ERR) error conditions
1361 4 (KERN_WARNING) warning conditions
1362 5 (KERN_NOTICE) normal but significant condition
1363 6 (KERN_INFO) informational
1364 7 (KERN_DEBUG) debug-level messages
1366 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1367 in bytes. n must be a power of two. The default
1368 size is set in the kernel config file.
1370 logo.nologo [FB] Disables display of the built-in Linux logo.
1371 This may be used to provide more screen space for
1372 kernel log messages and is useful when debugging
1373 kernel boot problems.
1375 lp=0 [LP] Specify parallel ports to use, e.g,
1376 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1377 lp=reset first parallel port). 'lp=0' disables the
1378 lp=auto printer driver. 'lp=reset' (which can be
1379 specified in addition to the ports) causes
1380 attached printers to be reset. Using
1381 lp=port1,port2,... specifies the parallel ports
1382 to associate lp devices with, starting with
1383 lp0. A port specification may be 'none' to skip
1384 that lp device, or a parport name such as
1385 'parport0'. Specifying 'lp=auto' instead of a
1386 port specification list means that device IDs
1387 from each port should be examined, to see if
1388 an IEEE 1284-compliant printer is attached; if
1389 so, the driver will manage that printer.
1390 See also header of drivers/char/lp.c.
1393 Sets loops_per_jiffy to given constant, thus avoiding
1394 time-consuming boot-time autodetection (up to 250 ms per
1395 CPU). 0 enables autodetection (default). To determine
1396 the correct value for your kernel, boot with normal
1397 autodetection and see what value is printed. Note that
1398 on SMP systems the preset will be applied to all CPUs,
1399 which is likely to cause problems if your CPUs need
1400 significantly divergent settings. An incorrect value
1401 will cause delays in the kernel to be wrong, leading to
1402 unpredictable I/O errors and other breakage. Although
1403 unlikely, in the extreme case this might damage your
1407 Format: <io>,<irq>,<dma>
1409 machvec= [IA-64] Force the use of a particular machine-vector
1410 (machvec) in a generic kernel.
1411 Example: machvec=hpzx1_swiotlb
1413 machtype= [Loongson] Share the same kernel image file between different
1415 Example: machtype=lemote-yeeloong-2f-7inch
1417 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1418 than or equal to this physical address is ignored.
1420 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1421 should make use of. maxcpus=n : n >= 0 limits the
1422 kernel to using 'n' processors. n=0 is a special case,
1423 it is equivalent to "nosmp", which also disables
1426 max_loop= [LOOP] The number of loop block devices that get
1427 (loop.max_loop) unconditionally pre-created at init time. The default
1428 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1429 of statically allocating a predefined number, loop
1430 devices can be requested on-demand with the
1431 /dev/loop-control interface.
1435 mce [X86-32] Machine Check Exception
1437 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1439 md= [HW] RAID subsystems devices and level
1440 See Documentation/md.txt.
1443 Format: <first>,<last>
1444 Specifies range of consoles to be captured by the MDA.
1446 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1447 Amount of memory to be used when the kernel is not able
1448 to see the whole system memory or for test.
1449 [X86-32] Use together with memmap= to avoid physical
1450 address space collisions. Without memmap= PCI devices
1451 could be placed at addresses belonging to unused RAM.
1453 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1457 [KNL,SH] Allow user to override the default size for
1458 per-device physically contiguous DMA buffers.
1460 memmap=exactmap [KNL,X86] Enable setting of an exact
1461 E820 memory map, as specified by the user.
1462 Such memmap=exactmap lines can be constructed based on
1463 BIOS output or other requirements. See the memmap=nn@ss
1466 memmap=nn[KMG]@ss[KMG]
1467 [KNL] Force usage of a specific region of memory
1468 Region of memory to be used, from ss to ss+nn.
1470 memmap=nn[KMG]#ss[KMG]
1471 [KNL,ACPI] Mark specific memory as ACPI data.
1472 Region of memory to be used, from ss to ss+nn.
1474 memmap=nn[KMG]$ss[KMG]
1475 [KNL,ACPI] Mark specific memory as reserved.
1476 Region of memory to be used, from ss to ss+nn.
1477 Example: Exclude memory from 0x18690000-0x1869ffff
1478 memmap=64K$0x18690000
1480 memmap=0x10000$0x18690000
1482 memory_corruption_check=0/1 [X86]
1483 Some BIOSes seem to corrupt the first 64k of
1484 memory when doing things like suspend/resume.
1485 Setting this option will scan the memory
1486 looking for corruption. Enabling this will
1487 both detect corruption and prevent the kernel
1488 from using the memory being corrupted.
1489 However, its intended as a diagnostic tool; if
1490 repeatable BIOS-originated corruption always
1491 affects the same memory, you can use memmap=
1492 to prevent the kernel from using that memory.
1494 memory_corruption_check_size=size [X86]
1495 By default it checks for corruption in the low
1496 64k, making this memory unavailable for normal
1497 use. Use this parameter to scan for
1498 corruption in more or less memory.
1500 memory_corruption_check_period=seconds [X86]
1501 By default it checks for corruption every 60
1502 seconds. Use this parameter to check at some
1503 other rate. 0 disables periodic checking.
1505 memtest= [KNL,X86] Enable memtest
1507 default : 0 <disable>
1508 Specifies the number of memtest passes to be
1509 performed. Each pass selects another test
1510 pattern from a given set of patterns. Memtest
1511 fills the memory with this pattern, validates
1512 memory contents and reserves bad memory
1513 regions that are detected.
1515 meye.*= [HW] Set MotionEye Camera parameters
1516 See Documentation/video4linux/meye.txt.
1518 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1519 Multi-Function General Purpose Timers on AMD Geode
1522 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1523 the BIOS has incorrectly applied a workaround. TinyBIOS
1524 version 0.98 is known to be affected, 0.99 fixes the
1525 problem by letting the user disable the workaround.
1529 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1530 physical address is ignored.
1532 mini2440= [ARM,HW,KNL]
1533 Format:[0..2][b][c][t]
1535 MINI2440 configuration specification:
1536 0 - The attached screen is the 3.5" TFT
1537 1 - The attached screen is the 7" TFT
1538 2 - The VGA Shield is attached (1024x768)
1539 Leaving out the screen size parameter will not load
1540 the TFT driver, and the framebuffer will be left
1542 b - Enable backlight. The TFT backlight pin will be
1543 linked to the kernel VESA blanking code and a GPIO
1544 LED. This parameter is not necessary when using the
1546 c - Enable the s3c camera interface.
1547 t - Reserved for enabling touchscreen support. The
1548 touchscreen support is not enabled in the mainstream
1549 kernel as of 2.6.30, a preliminary port can be found
1550 in the "bleeding edge" mini2440 support kernel at
1551 http://repo.or.cz/w/linux-2.6/mini2440.git
1554 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1555 parameter allows control of the logging verbosity for
1556 the additional memory initialisation checks. A value
1557 of 0 disables mminit logging and a level of 4 will
1558 log everything. Information is printed at KERN_DEBUG
1559 so loglevel=8 may also need to be specified.
1562 [MOUSE] Maximum time between finger touching and
1563 leaving touchpad surface for touch to be considered
1564 a tap and be reported as a left button click (for
1565 touchpads working in absolute mode only).
1567 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1568 reporting absolute coordinates, such as tablets
1569 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1570 reporting absolute coordinates, such as tablets
1572 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1573 is similar to kernelcore except it specifies the
1574 amount of memory used for migratable allocations.
1575 If both kernelcore and movablecore is specified,
1576 then kernelcore will be at *least* the specified
1577 value but may be more. If movablecore on its own
1578 is specified, the administrator must be careful
1579 that the amount of memory usable for all allocations
1582 MTD_Partition= [MTD]
1583 Format: <name>,<region-number>,<size>,<offset>
1585 MTD_Region= [MTD] Format:
1586 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1589 See drivers/mtd/cmdlinepart.c.
1591 multitce=off [PPC] This parameter disables the use of the pSeries
1592 firmware feature for updating multiple TCE entries
1595 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1597 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1599 boundary - index of last SLC block on Flex-OneNAND.
1600 The remaining blocks are configured as MLC blocks.
1601 lock - Configure if Flex-OneNAND boundary should be locked.
1602 Once locked, the boundary cannot be changed.
1603 1 indicates lock status, 0 indicates unlock status.
1606 ARM/S3C2412 JIVE boot control
1608 See arch/arm/mach-s3c2412/mach-jive.c
1610 mtouchusb.raw_coordinates=
1611 [HW] Make the MicroTouch USB driver use raw coordinates
1612 ('y', default) or cooked coordinates ('n')
1614 mtrr_chunk_size=nn[KMG] [X86]
1615 used for mtrr cleanup. It is largest continuous chunk
1616 that could hold holes aka. UC entries.
1618 mtrr_gran_size=nn[KMG] [X86]
1619 Used for mtrr cleanup. It is granularity of mtrr block.
1621 Large value could prevent small alignment from
1624 mtrr_spare_reg_nr=n [X86]
1626 Range: 0,7 : spare reg number
1628 Used for mtrr cleanup. It is spare mtrr entries number.
1629 Set to 2 or more if your graphical card needs more.
1631 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1633 netdev= [NET] Network devices parameters
1634 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1635 Note that mem_start is often overloaded to mean
1636 something different and driver-specific.
1637 This usage is only documented in each driver source
1641 [NETFILTER] Enable connection tracking flow accounting
1642 0 to disable accounting
1643 1 to enable accounting
1646 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1647 See Documentation/filesystems/nfs/nfsroot.txt.
1649 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1650 See Documentation/filesystems/nfs/nfsroot.txt.
1652 nfsrootdebug [NFS] enable nfsroot debugging messages.
1653 See Documentation/filesystems/nfs/nfsroot.txt.
1655 nfs.callback_tcpport=
1656 [NFS] set the TCP port on which the NFSv4 callback
1657 channel should listen.
1660 [NFS] sets the pathname to the program which is used
1661 to update the NFS client cache entries.
1663 nfs.cache_getent_timeout=
1664 [NFS] sets the timeout after which an attempt to
1665 update a cache entry is deemed to have failed.
1667 nfs.idmap_cache_timeout=
1668 [NFS] set the maximum lifetime for idmapper cache
1672 [NFS] enable 64-bit inode numbers.
1673 If zero, the NFS client will fake up a 32-bit inode
1674 number for the readdir() and stat() syscalls instead
1675 of returning the full 64-bit number.
1676 The default is to return 64-bit inode numbers.
1678 nfs.max_session_slots=
1679 [NFSv4.1] Sets the maximum number of session slots
1680 the client will attempt to negotiate with the server.
1681 This limits the number of simultaneous RPC requests
1682 that the client can send to the NFSv4.1 server.
1683 Note that there is little point in setting this
1684 value higher than the max_tcp_slot_table_limit.
1686 nfs.nfs4_disable_idmapping=
1687 [NFSv4] When set to the default of '1', this option
1688 ensures that both the RPC level authentication
1689 scheme and the NFS level operations agree to use
1690 numeric uids/gids if the mount is using the
1691 'sec=sys' security flavour. In effect it is
1692 disabling idmapping, which can make migration from
1693 legacy NFSv2/v3 systems to NFSv4 easier.
1694 Servers that do not support this mode of operation
1695 will be autodetected by the client, and it will fall
1696 back to using the idmapper.
1697 To turn off this behaviour, set the value to '0'.
1699 nfs.send_implementation_id =
1700 [NFSv4.1] Send client implementation identification
1701 information in exchange_id requests.
1702 If zero, no implementation identification information
1704 The default is to send the implementation identification
1707 nfsd.nfs4_disable_idmapping=
1708 [NFSv4] When set to the default of '1', the NFSv4
1709 server will return only numeric uids and gids to
1710 clients using auth_sys, and will accept numeric uids
1711 and gids from such clients. This is intended to ease
1712 migration from NFSv2/v3.
1714 objlayoutdriver.osd_login_prog=
1715 [NFS] [OBJLAYOUT] sets the pathname to the program which
1716 is used to automatically discover and login into new
1717 osd-targets. Please see:
1718 Documentation/filesystems/pnfs.txt for more explanations
1720 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1721 when a NMI is triggered.
1722 Format: [state][,regs][,debounce][,die]
1724 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1725 Format: [panic,][nopanic,][num]
1727 0 - turn nmi_watchdog off
1728 When panic is specified, panic when an NMI watchdog
1729 timeout occurs (or 'nopanic' to override the opposite
1731 This is useful when you use a panic=... timeout and
1732 need the box quickly up again.
1734 netpoll.carrier_timeout=
1735 [NET] Specifies amount of time (in seconds) that
1736 netpoll should wait for a carrier. By default netpoll
1739 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1740 emulation library even if a 387 maths coprocessor
1744 [HW] Never suspend the console
1745 Disable suspending of consoles during suspend and
1746 hibernate operations. Once disabled, debugging
1747 messages can reach various consoles while the rest
1748 of the system is being put to sleep (ie, while
1749 debugging driver suspend/resume hooks). This may
1750 not work reliably with all consoles, but is known
1751 to work with serial and VGA consoles.
1752 To facilitate more flexible debugging, we also add
1753 console_suspend, a printk module parameter to control
1754 it. Users could use console_suspend (usually
1755 /sys/module/printk/parameters/console_suspend) to
1756 turn on/off it dynamically.
1758 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1759 caches in the slab allocator. Saves per-node memory,
1760 but will impact performance.
1764 noapic [SMP,APIC] Tells the kernel to not make use of any
1765 IOAPICs that may be present in the system.
1767 noautogroup Disable scheduler automatic task group creation.
1769 nobats [PPC] Do not use BATs for mapping kernel lowmem
1770 on "Classic" PPC cores.
1774 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1776 nodelayacct [KNL] Disable per-task delay accounting
1778 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1780 nodsp [SH] Disable hardware DSP at boot time.
1782 noefi [X86] Disable EFI runtime services support.
1787 On X86-32 available only on PAE configured kernels.
1788 noexec=on: enable non-executable mappings (default)
1789 noexec=off: disable non-executable mappings
1792 Disable SMEP (Supervisor Mode Execution Protection)
1793 even if it is supported by processor.
1796 This affects only 32-bit executables.
1797 noexec32=on: enable non-executable mappings (default)
1798 read doesn't imply executable mappings
1799 noexec32=off: disable non-executable mappings
1800 read implies executable mappings
1802 nofpu [SH] Disable hardware FPU at boot time.
1804 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1805 register save and restore. The kernel will only save
1806 legacy floating-point registers on task switch.
1808 noxsave [BUGS=X86] Disables x86 extended register state save
1809 and restore using xsave. The kernel will fallback to
1810 enabling legacy floating-point and sse state.
1812 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1813 wfi(ARM) instruction doesn't work correctly and not to
1814 use it. This is also useful when using JTAG debugger.
1816 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1817 instruction doesn't work correctly and not to
1820 no_file_caps Tells the kernel not to honor file capabilities. The
1821 only way then for a file to be executed with privilege
1822 is to be setuid root or executed by root.
1824 nohalt [IA-64] Tells the kernel not to use the power saving
1825 function PAL_HALT_LIGHT when idle. This increases
1826 power-consumption. On the positive side, it reduces
1827 interrupt wake-up latency, which may improve performance
1828 in certain environments such as networked servers or
1831 nohz= [KNL] Boottime enable/disable dynamic ticks
1832 Valid arguments: on, off
1835 noiotrap [SH] Disables trapped I/O port accesses.
1837 noirqdebug [X86-32] Disables the code which attempts to detect and
1838 disable unhandled interrupt sources.
1840 no_timer_check [X86,APIC] Disables the code which tests for
1841 broken timer IRQ sources.
1843 noisapnp [ISAPNP] Disables ISA PnP code.
1845 noinitrd [RAM] Tells the kernel not to load any configured
1848 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1850 [Deprecated - use intremap=off]
1854 nojitter [IA-64] Disables jitter checking for ITC timers.
1856 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1858 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1861 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1862 steal time is computed, but won't influence scheduler
1865 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1867 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1869 noltlbs [PPC] Do not use large page/tlb entries for kernel
1870 lowmem mapping on PPC40x.
1872 nomca [IA-64] Disable machine check abort handling
1874 nomce [X86-32] Machine Check Exception
1876 nomfgpt [X86-32] Disable Multi-Function General Purpose
1877 Timer usage (for AMD Geode machines).
1879 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
1880 shutdown the other cpus. Instead use the REBOOT_VECTOR
1883 nomodule Disable module load
1885 nopat [X86] Disable PAT (page attribute table extension of
1886 pagetables) support.
1888 norandmaps Don't use address space randomization. Equivalent to
1889 echo 0 > /proc/sys/kernel/randomize_va_space
1891 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1893 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1894 with UP alternatives
1896 noresidual [PPC] Don't use residual data on PReP machines.
1898 nordrand [X86] Disable the direct use of the RDRAND
1899 instruction even if it is supported by the
1900 processor. RDRAND is still available to user
1903 noresume [SWSUSP] Disables resume and restores original swap
1906 no-scroll [VGA] Disables scrollback.
1907 This is required for the Braillex ib80-piezo Braille
1908 reader made by F.H. Papenmeier (Germany).
1912 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1914 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1915 and disable the IO APIC. legacy for "maxcpus=0".
1917 nosoftlockup [KNL] Disable the soft-lockup detector.
1919 nosync [HW,M68K] Disables sync negotiation for all devices.
1921 notsc [BUGS=X86-32] Disable Time Stamp Counter
1923 nousb [USB] Disable the USB subsystem
1925 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1929 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1931 nptcg= [IA-64] Override max number of concurrent global TLB
1932 purges which is reported from either PAL_VM_SUMMARY or
1935 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1936 could support. nr_cpus=n : n >= 1 limits the kernel to
1937 supporting 'n' processors. Later in runtime you can not
1938 use hotplug cpu feature to put more cpu back to online.
1939 just like you compile the kernel NR_CPUS=n
1941 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1943 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1944 one of ['zone', 'node', 'default'] can be specified
1945 This can be set from sysctl after boot.
1946 See Documentation/sysctl/vm.txt for details.
1948 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1949 See Documentation/debugging-via-ohci1394.txt for more
1952 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1953 Rather than timing out after 20 ms if an EC
1954 command is not properly ACKed, override the length
1955 of the timeout. We have interrupts disabled while
1956 waiting for the ACK, so if this is set too high
1957 interrupts *may* be lost!
1959 omap_mux= [OMAP] Override bootloader pin multiplexing.
1960 Format: <mux_mode0.mode_name=value>...
1961 For example, to override I2C bus2:
1962 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1964 oprofile.timer= [HW]
1965 Use timer interrupt instead of performance counters
1967 oprofile.cpu_type= Force an oprofile cpu type
1968 This might be useful if you have an older oprofile
1969 userland or if you want common events.
1970 Format: { arch_perfmon }
1971 arch_perfmon: [X86] Force use of architectural
1972 perfmon on Intel CPUs instead of the
1973 CPU specific event set.
1974 timer: [X86] Force use of architectural NMI
1975 timer mode (see also oprofile.timer
1976 for generic hr timer mode)
1977 [s390] Force legacy basic mode sampling
1978 (report cpu_type "timer")
1980 oops=panic Always panic on oopses. Default is to just kill the
1981 process, but there is a small probability of
1982 deadlocking the machine.
1983 This will also cause panics on machine check exceptions.
1984 Useful together with panic=30 to trigger a reboot.
1987 See Documentation/sound/oss/oss-parameters.txt
1989 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1990 timeout > 0: seconds before rebooting
1991 timeout = 0: wait forever
1992 timeout < 0: reboot immediately
1995 parkbd.port= [HW] Parallel port number the keyboard adapter is
1996 connected to, default is 0.
1998 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1999 0 for XT, 1 for AT (default is AT).
2002 parport= [HW,PPT] Specify parallel ports. 0 disables.
2003 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2004 Use 'auto' to force the driver to use any
2005 IRQ/DMA settings detected (the default is to
2006 ignore detected IRQ/DMA settings because of
2007 possible conflicts). You can specify the base
2008 address, IRQ, and DMA settings; IRQ and DMA
2009 should be numbers, or 'auto' (for using detected
2010 settings on that particular port), or 'nofifo'
2011 (to avoid using a FIFO even if it is detected).
2012 Parallel ports are assigned in the order they
2013 are specified on the command line, starting
2016 parport_init_mode= [HW,PPT]
2017 Configure VIA parallel port to operate in
2018 a specific mode. This is necessary on Pegasos
2019 computer where firmware has no options for setting
2020 up parallel port mode and sets it to spp.
2021 Currently this function knows 686a and 8231 chips.
2022 Format: [spp|ps2|epp|ecp|ecpepp]
2025 Halt all CPUs after the first oops has been printed for
2026 the specified number of seconds. This is to be used if
2027 your oopses keep scrolling off the screen.
2032 See header of drivers/block/paride/pcd.c.
2033 See also Documentation/blockdev/paride.txt.
2035 pci=option[,option...] [PCI] various PCI subsystem options:
2036 earlydump [X86] dump PCI config space before the kernel
2038 off [X86] don't probe for the PCI bus
2039 bios [X86-32] force use of PCI BIOS, don't access
2040 the hardware directly. Use this if your machine
2041 has a non-standard PCI host bridge.
2042 nobios [X86-32] disallow use of PCI BIOS, only direct
2043 hardware access methods are allowed. Use this
2044 if you experience crashes upon bootup and you
2045 suspect they are caused by the BIOS.
2046 conf1 [X86] Force use of PCI Configuration
2048 conf2 [X86] Force use of PCI Configuration
2050 noaer [PCIE] If the PCIEAER kernel config parameter is
2051 enabled, this kernel boot option can be used to
2052 disable the use of PCIE advanced error reporting.
2053 nodomains [PCI] Disable support for multiple PCI
2054 root domains (aka PCI segments, in ACPI-speak).
2055 nommconf [X86] Disable use of MMCONFIG for PCI
2057 check_enable_amd_mmconf [X86] check for and enable
2058 properly configured MMIO access to PCI
2059 config space on AMD family 10h CPU
2060 nomsi [MSI] If the PCI_MSI kernel config parameter is
2061 enabled, this kernel boot option can be used to
2062 disable the use of MSI interrupts system-wide.
2063 noioapicquirk [APIC] Disable all boot interrupt quirks.
2064 Safety option to keep boot IRQs enabled. This
2065 should never be necessary.
2066 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2067 primary IO-APIC for bridges that cannot disable
2068 boot IRQs. This fixes a source of spurious IRQs
2069 when the system masks IRQs.
2070 noioapicreroute [APIC] Disable workaround that uses the
2071 boot IRQ equivalent of an IRQ that connects to
2072 a chipset where boot IRQs cannot be disabled.
2073 The opposite of ioapicreroute.
2074 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2075 routing table. These calls are known to be buggy
2076 on several machines and they hang the machine
2077 when used, but on other computers it's the only
2078 way to get the interrupt routing table. Try
2079 this option if the kernel is unable to allocate
2080 IRQs or discover secondary PCI buses on your
2082 rom [X86] Assign address space to expansion ROMs.
2083 Use with caution as certain devices share
2084 address decoders between ROMs and other
2086 norom [X86] Do not assign address space to
2087 expansion ROMs that do not already have
2088 BIOS assigned address ranges.
2089 nobar [X86] Do not assign address space to the
2090 BARs that weren't assigned by the BIOS.
2091 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2092 assigned automatically to PCI devices. You can
2093 make the kernel exclude IRQs of your ISA cards
2095 pirqaddr=0xAAAAA [X86] Specify the physical address
2096 of the PIRQ table (normally generated
2097 by the BIOS) if it is outside the
2098 F0000h-100000h range.
2099 lastbus=N [X86] Scan all buses thru bus #N. Can be
2100 useful if the kernel is unable to find your
2101 secondary buses and you want to tell it
2102 explicitly which ones they are.
2103 assign-busses [X86] Always assign all PCI bus
2104 numbers ourselves, overriding
2105 whatever the firmware may have done.
2106 usepirqmask [X86] Honor the possible IRQ mask stored
2107 in the BIOS $PIR table. This is needed on
2108 some systems with broken BIOSes, notably
2109 some HP Pavilion N5400 and Omnibook XE3
2110 notebooks. This will have no effect if ACPI
2111 IRQ routing is enabled.
2112 noacpi [X86] Do not use ACPI for IRQ routing
2113 or for PCI scanning.
2114 use_crs [X86] Use PCI host bridge window information
2115 from ACPI. On BIOSes from 2008 or later, this
2116 is enabled by default. If you need to use this,
2117 please report a bug.
2118 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2119 If you need to use this, please report a bug.
2120 routeirq Do IRQ routing for all PCI devices.
2121 This is normally done in pci_enable_device(),
2122 so this option is a temporary workaround
2123 for broken drivers that don't call it.
2124 skip_isa_align [X86] do not align io start addr, so can
2125 handle more pci cards
2126 firmware [ARM] Do not re-enumerate the bus but instead
2127 just use the configuration from the
2128 bootloader. This is currently used on
2129 IXP2000 systems where the bus has to be
2130 configured a certain way for adjunct CPUs.
2131 noearly [X86] Don't do any early type 1 scanning.
2132 This might help on some broken boards which
2133 machine check when some devices' config space
2134 is read. But various workarounds are disabled
2135 and some IOMMU drivers will not work.
2136 bfsort Sort PCI devices into breadth-first order.
2137 This sorting is done to get a device
2138 order compatible with older (<= 2.4) kernels.
2139 nobfsort Don't sort PCI devices into breadth-first order.
2140 cbiosize=nn[KMG] The fixed amount of bus space which is
2141 reserved for the CardBus bridge's IO window.
2142 The default value is 256 bytes.
2143 cbmemsize=nn[KMG] The fixed amount of bus space which is
2144 reserved for the CardBus bridge's memory
2145 window. The default value is 64 megabytes.
2148 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2149 Specifies alignment and device to reassign
2150 aligned memory resources.
2151 If <order of align> is not specified,
2152 PAGE_SIZE is used as alignment.
2153 PCI-PCI bridge can be specified, if resource
2154 windows need to be expanded.
2155 ecrc= Enable/disable PCIe ECRC (transaction layer
2156 end-to-end CRC checking).
2157 bios: Use BIOS/firmware settings. This is the
2161 realloc= Enable/disable reallocating PCI bridge resources
2162 if allocations done by BIOS are too small to
2163 accommodate resources required by all child
2165 off: Turn realloc off
2167 realloc same as realloc=on
2168 noari do not use PCIe ARI.
2169 pcie_scan_all Scan all possible PCIe devices. Otherwise we
2170 only look for one device below a PCIe downstream
2173 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2176 force Enable ASPM even on devices that claim not to support it.
2177 WARNING: Forcing ASPM on may cause system lockups.
2179 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2180 nomsi Do not use MSI for PCI Express Native Hotplug (this
2181 makes all PCIe ports use INTx for hotplug services).
2183 pcie_ports= [PCIE] PCIe ports handling:
2184 auto Ask the BIOS whether or not to use native PCIe services
2185 associated with PCIe ports (PME, hot-plug, AER). Use
2186 them only if that is allowed by the BIOS.
2187 native Use native PCIe services associated with PCIe ports
2189 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2192 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2193 nomsi Do not use MSI for native PCIe PME signaling (this makes
2194 all PCIe root ports use INTx for all services).
2196 pcmv= [HW,PCMCIA] BadgePAD 4
2199 See Documentation/blockdev/paride.txt.
2201 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2204 See arch/parisc/kernel/pdc_chassis.c
2206 percpu_alloc= Select which percpu first chunk allocator to use.
2207 Currently supported values are "embed" and "page".
2208 Archs may support subset or none of the selections.
2209 See comments in mm/percpu.c for details on each
2210 allocator. This parameter is primarily for debugging
2211 and performance comparison.
2214 See Documentation/blockdev/paride.txt.
2217 See Documentation/blockdev/paride.txt.
2219 pirq= [SMP,APIC] Manual mp-table setup
2220 See Documentation/x86/i386/IO-APIC.txt.
2222 plip= [PPT,NET] Parallel port network link
2223 Format: { parport<nr> | timid | 0 }
2224 See also Documentation/parport.txt.
2226 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2227 Override pmtimer IOPort with a hex value.
2231 Enable PNP debug messages (depends on the
2232 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2233 via /sys/module/pnp/parameters/debug. We always show
2234 current resource usage; turning this on also shows
2235 possible settings and some assignment information.
2241 { on | off | curr | res | no-curr | no-res }
2244 [ISAPNP] Exclude IRQs for the autoconfiguration
2247 [ISAPNP] Exclude DMAs for the autoconfiguration
2249 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2250 Ranges are in pairs (I/O port base and size).
2253 [ISAPNP] Exclude memory regions for the
2255 Ranges are in pairs (memory base and size).
2257 ports= [IP_VS_FTP] IPVS ftp helper module
2259 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2261 Format: <port>,<port>....
2263 print-fatal-signals=
2264 [KNL] debug: print fatal signals
2266 If enabled, warn about various signal handling
2267 related application anomalies: too many signals,
2268 too many POSIX.1 timers, fatal signals causing a
2271 If you hit the warning due to signal overflow,
2272 you might want to try "ulimit -i unlimited".
2276 printk.always_kmsg_dump=
2277 Trigger kmsg_dump for cases other than kernel oops or
2279 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2282 printk.time= Show timing data prefixed to each printk message line
2283 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2285 processor.max_cstate= [HW,ACPI]
2286 Limit processor to maximum C-state
2287 max_cstate=9 overrides any DMI blacklist limit.
2289 processor.nocst [HW,ACPI]
2290 Ignore the _CST method to determine C-states,
2291 instead using the legacy FADT method
2293 profile= [KNL] Enable kernel profiling via /proc/profile
2294 Format: [schedule,]<number>
2295 Param: "schedule" - profile schedule points.
2296 Param: <number> - step/bucket size as a power of 2 for
2297 statistical time based profiling.
2298 Param: "sleep" - profile D-state sleeping (millisecs).
2299 Requires CONFIG_SCHEDSTATS
2300 Param: "kvm" - profile VM exits.
2302 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2304 See Documentation/blockdev/ramdisk.txt.
2306 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2307 probe for; one of (bare|imps|exps|lifebook|any).
2308 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2310 psmouse.resetafter= [HW,MOUSE]
2311 Try to reset the device after so many bad packets
2314 [HW,MOUSE] Set desired mouse resolution, in dpi.
2315 psmouse.smartscroll=
2316 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2317 0 = disabled, 1 = enabled (default).
2319 pstore.backend= Specify the name of the pstore backend to use
2322 See Documentation/blockdev/paride.txt.
2325 [KNL] Number of legacy pty's. Overwrites compiled-in
2328 quiet [KNL] Disable most log messages
2333 See Documentation/md.txt.
2335 ramdisk_blocksize= [RAM]
2336 See Documentation/blockdev/ramdisk.txt.
2338 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2339 See Documentation/blockdev/ramdisk.txt.
2341 rcutree.blimit= [KNL,BOOT]
2342 Set maximum number of finished RCU callbacks to process
2345 rcutree.qhimark= [KNL,BOOT]
2346 Set threshold of queued
2347 RCU callbacks over which batch limiting is disabled.
2349 rcutree.qlowmark= [KNL,BOOT]
2350 Set threshold of queued RCU callbacks below which
2351 batch limiting is re-enabled.
2353 rcutree.rcu_cpu_stall_suppress= [KNL,BOOT]
2354 Suppress RCU CPU stall warning messages.
2356 rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
2357 Set timeout for RCU CPU stall warning messages.
2359 rcutorture.fqs_duration= [KNL,BOOT]
2360 Set duration of force_quiescent_state bursts.
2362 rcutorture.fqs_holdoff= [KNL,BOOT]
2363 Set holdoff time within force_quiescent_state bursts.
2365 rcutorture.fqs_stutter= [KNL,BOOT]
2366 Set wait time between force_quiescent_state bursts.
2368 rcutorture.irqreader= [KNL,BOOT]
2369 Test RCU readers from irq handlers.
2371 rcutorture.n_barrier_cbs= [KNL,BOOT]
2372 Set callbacks/threads for rcu_barrier() testing.
2374 rcutorture.nfakewriters= [KNL,BOOT]
2375 Set number of concurrent RCU writers. These just
2376 stress RCU, they don't participate in the actual
2377 test, hence the "fake".
2379 rcutorture.nreaders= [KNL,BOOT]
2380 Set number of RCU readers.
2382 rcutorture.onoff_holdoff= [KNL,BOOT]
2383 Set time (s) after boot for CPU-hotplug testing.
2385 rcutorture.onoff_interval= [KNL,BOOT]
2386 Set time (s) between CPU-hotplug operations, or
2387 zero to disable CPU-hotplug testing.
2389 rcutorture.shuffle_interval= [KNL,BOOT]
2390 Set task-shuffle interval (s). Shuffling tasks
2391 allows some CPUs to go into dyntick-idle mode
2392 during the rcutorture test.
2394 rcutorture.shutdown_secs= [KNL,BOOT]
2395 Set time (s) after boot system shutdown. This
2396 is useful for hands-off automated testing.
2398 rcutorture.stall_cpu= [KNL,BOOT]
2399 Duration of CPU stall (s) to test RCU CPU stall
2400 warnings, zero to disable.
2402 rcutorture.stall_cpu_holdoff= [KNL,BOOT]
2403 Time to wait (s) after boot before inducing stall.
2405 rcutorture.stat_interval= [KNL,BOOT]
2406 Time (s) between statistics printk()s.
2408 rcutorture.stutter= [KNL,BOOT]
2409 Time (s) to stutter testing, for example, specifying
2410 five seconds causes the test to run for five seconds,
2411 wait for five seconds, and so on. This tests RCU's
2412 ability to transition abruptly to and from idle.
2414 rcutorture.test_boost= [KNL,BOOT]
2415 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
2416 "Maybe" means test if the RCU implementation
2417 under test support RCU priority boosting.
2419 rcutorture.test_boost_duration= [KNL,BOOT]
2420 Duration (s) of each individual boost test.
2422 rcutorture.test_boost_interval= [KNL,BOOT]
2423 Interval (s) between each boost test.
2425 rcutorture.test_no_idle_hz= [KNL,BOOT]
2426 Test RCU's dyntick-idle handling. See also the
2427 rcutorture.shuffle_interval parameter.
2429 rcutorture.torture_type= [KNL,BOOT]
2430 Specify the RCU implementation to test.
2432 rcutorture.verbose= [KNL,BOOT]
2433 Enable additional printk() statements.
2437 Run specified binary instead of /init from the ramdisk,
2438 used for early userspace startup. See initrd.
2440 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2441 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2442 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2445 [KNL, SMP] Set scheduler's default relax_domain_level.
2446 See Documentation/cgroups/cpusets.txt.
2448 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2450 reservetop= [X86-32]
2452 Reserves a hole at the top of the kernel virtual
2457 Set the amount of memory to reserve for BIOS at
2458 the bottom of the address space.
2460 reset_devices [KNL] Force drivers to reset the underlying device
2461 during initialization.
2464 Specify the partition device for software suspend
2466 {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
2468 resume_offset= [SWSUSP]
2469 Specify the offset from the beginning of the partition
2470 given by "resume=" at which the swap header is located,
2471 in <PAGE_SIZE> units (needed only for swap files).
2472 See Documentation/power/swsusp-and-swap-files.txt
2474 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2475 read the resume files
2477 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2478 Useful for devices that are detected asynchronously
2479 (e.g. USB and MMC devices).
2481 hibernate= [HIBERNATION]
2482 noresume Don't check if there's a hibernation image
2483 present during boot.
2484 nocompress Don't compress/decompress hibernation images.
2486 retain_initrd [RAM] Keep initrd memory after extraction
2488 rhash_entries= [KNL,NET]
2489 Set number of hash buckets for route cache
2491 riscom8= [HW,SERIAL]
2492 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2494 ro [KNL] Mount root device read-only on boot
2496 root= [KNL] Root filesystem
2497 See name_to_dev_t comment in init/do_mounts.c.
2499 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2500 mount the root filesystem
2502 rootflags= [KNL] Set root filesystem mount option string
2504 rootfstype= [KNL] Set root filesystem type
2506 rootwait [KNL] Wait (indefinitely) for root device to show up.
2507 Useful for devices that are detected asynchronously
2508 (e.g. USB and MMC devices).
2510 rw [KNL] Mount root device read-write on boot
2512 S [KNL] Run init in single mode
2515 See drivers/net/irda/sa1100_ir.c.
2517 sbni= [NET] Granch SBNI12 leased line adapter
2519 sched_debug [KNL] Enables verbose scheduler debug messages.
2521 security= [SECURITY] Choose a security module to enable at boot.
2522 If this boot parameter is not specified, only the first
2523 security module asking for security registration will be
2524 loaded. An invalid security module name will be treated
2525 as if no module has been chosen.
2527 selinux= [SELINUX] Disable or enable SELinux at boot time.
2528 Format: { "0" | "1" }
2529 See security/selinux/Kconfig help text.
2532 Default value is set via kernel config option.
2533 If enabled at boot time, /selinux/disable can be used
2534 later to disable prior to initial policy load.
2536 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2537 Format: { "0" | "1" }
2538 See security/apparmor/Kconfig help text
2541 Default value is set via kernel config option.
2543 serialnumber [BUGS=X86-32]
2546 Maximal number of shapers.
2548 show_msr= [x86] show boot-time MSR settings
2549 Format: { <integer> }
2550 Show boot-time (BIOS-initialized) MSR settings.
2551 The parameter means the number of CPUs to show,
2552 for example 1 means boot CPU only.
2559 slab_max_order= [MM, SLAB]
2560 Determines the maximum allowed order for slabs.
2561 A high setting may cause OOMs due to memory
2562 fragmentation. Defaults to 1 for systems with
2563 more than 32MB of RAM, 0 otherwise.
2565 slub_debug[=options[,slabs]] [MM, SLUB]
2566 Enabling slub_debug allows one to determine the
2567 culprit if slab objects become corrupted. Enabling
2568 slub_debug can create guard zones around objects and
2569 may poison objects when not in use. Also tracks the
2570 last alloc / free. For more information see
2571 Documentation/vm/slub.txt.
2573 slub_max_order= [MM, SLUB]
2574 Determines the maximum allowed order for slabs.
2575 A high setting may cause OOMs due to memory
2576 fragmentation. For more information see
2577 Documentation/vm/slub.txt.
2579 slub_min_objects= [MM, SLUB]
2580 The minimum number of objects per slab. SLUB will
2581 increase the slab order up to slub_max_order to
2582 generate a sufficiently large slab able to contain
2583 the number of objects indicated. The higher the number
2584 of objects the smaller the overhead of tracking slabs
2585 and the less frequently locks need to be acquired.
2586 For more information see Documentation/vm/slub.txt.
2588 slub_min_order= [MM, SLUB]
2589 Determines the minimum page order for slabs. Must be
2590 lower than slub_max_order.
2591 For more information see Documentation/vm/slub.txt.
2593 slub_nomerge [MM, SLUB]
2594 Disable merging of slabs with similar size. May be
2595 necessary if there is some reason to distinguish
2596 allocs to different slabs. Debug options disable
2597 merging on their own.
2598 For more information see Documentation/vm/slub.txt.
2601 Format: <io1>[,<io2>[,...,<io8>]]
2603 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2604 attempt to substitute SMP alternatives once at boot.
2606 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2607 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2608 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2609 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2610 smsc-ircc2.ircc_irq= [HW] IRQ line
2611 smsc-ircc2.ircc_dma= [HW] DMA channel
2612 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2613 0: Toshiba Satellite 1800 (GP data pin select)
2614 1: Fast pin select (default)
2618 [KNL] Should the soft-lockup detector generate panics.
2621 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2622 See Documentation/laptops/sonypi.txt
2624 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2625 See Documentation/serial/specialix.txt.
2627 spia_io_base= [HW,MTD]
2633 Enabled the stack tracer on boot up.
2635 stacktrace_filter=[function-list]
2636 [FTRACE] Limit the functions that the stack tracer
2637 will trace at boot up. function-list is a comma separated
2638 list of functions. This list can be changed at run
2639 time by the stack_trace_filter file in the debugfs
2640 tracing directory. Note, this enables stack tracing
2641 and the stacktrace above is not needed.
2645 Set the STI (builtin display/keyboard on the HP-PARISC
2646 machines) console (graphic card) which should be used
2647 as the initial boot-console.
2648 See also comment in drivers/video/console/sticore.c.
2651 See comment in drivers/video/console/sticore.c.
2654 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2656 sunrpc.min_resvport=
2657 sunrpc.max_resvport=
2659 SunRPC servers often require that client requests
2660 originate from a privileged port (i.e. a port in the
2661 range 0 < portnr < 1024).
2662 An administrator who wishes to reserve some of these
2663 ports for other uses may adjust the range that the
2664 kernel's sunrpc client considers to be privileged
2665 using these two parameters to set the minimum and
2666 maximum port values.
2670 Control how the NFS server code allocates CPUs to
2671 service thread pools. Depending on how many NICs
2672 you have and where their interrupts are bound, this
2673 option will affect which CPUs will do NFS serving.
2674 Note: this parameter cannot be changed while the
2675 NFS server is running.
2677 auto the server chooses an appropriate mode
2678 automatically using heuristics
2679 global a single global pool contains all CPUs
2680 percpu one pool for each CPU
2681 pernode one pool for each NUMA node (equivalent
2682 to global on non-NUMA machines)
2684 sunrpc.tcp_slot_table_entries=
2685 sunrpc.udp_slot_table_entries=
2687 Sets the upper limit on the number of simultaneous
2688 RPC calls that can be sent from the client to a
2689 server. Increasing these values may allow you to
2690 improve throughput, but will also increase the
2691 amount of memory reserved for use by the client.
2694 [KNL] Enable accounting of swap in memory resource
2695 controller if no parameter or 1 is given or disable
2696 it if 0 is given (See Documentation/cgroups/memory.txt)
2698 swiotlb= [IA-64] Number of I/O TLB slabs
2702 sysfs.deprecated=0|1 [KNL]
2703 Enable/disable old style sysfs layout for old udev
2704 on older distributions. When this option is enabled
2705 very new udev will not work anymore. When this option
2706 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2707 in older udev will not work anymore.
2708 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2709 the kernel configuration.
2711 sysrq_always_enabled
2713 Ignore sysrq setting - this boot parameter will
2714 neutralize any effect of /proc/sys/kernel/sysrq.
2715 Useful for debugging.
2719 test_suspend= [SUSPEND]
2720 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2721 standby suspend) as the system sleep state to briefly
2722 enter during system startup. The system is woken from
2723 this state using a wakeup-capable RTC alarm.
2725 thash_entries= [KNL,NET]
2726 Set number of hash buckets for TCP connection
2728 thermal.act= [HW,ACPI]
2729 -1: disable all active trip points in all thermal zones
2730 <degrees C>: override all lowest active trip points
2732 thermal.crt= [HW,ACPI]
2733 -1: disable all critical trip points in all thermal zones
2734 <degrees C>: override all critical trip points
2736 thermal.nocrt= [HW,ACPI]
2737 Set to disable actions on ACPI thermal zone
2738 critical and hot trip points.
2740 thermal.off= [HW,ACPI]
2741 1: disable ACPI thermal control
2743 thermal.psv= [HW,ACPI]
2744 -1: disable all passive trip points
2745 <degrees C>: override all passive trip points to this
2748 thermal.tzp= [HW,ACPI]
2749 Specify global default ACPI thermal zone polling rate
2750 <deci-seconds>: poll all this frequency
2751 0: no polling (default)
2754 Force threading of all interrupt handlers except those
2755 marked explicitly IRQF_NO_THREAD.
2759 Specify if the kernel should make use of the cpu
2760 topology information if the hardware supports this.
2761 The scheduler will make use of this information and
2762 e.g. base its process migration decisions on it.
2767 tpm_suspend_pcr=[HW,TPM]
2768 Format: integer pcr id
2769 Specify that at suspend time, the tpm driver
2770 should extend the specified pcr with zeros,
2771 as a workaround for some chips which fail to
2772 flush the last written pcr on TPM_SaveState.
2773 This will guarantee that all the other pcrs
2776 trace_buf_size=nn[KMG]
2777 [FTRACE] will set tracing buffer size.
2779 trace_event=[event-list]
2780 [FTRACE] Set and start specified trace events in order
2781 to facilitate early boot debugging.
2782 See also Documentation/trace/events.txt
2784 transparent_hugepage=
2786 Format: [always|madvise|never]
2787 Can be used to control the default behavior of the system
2788 with respect to transparent hugepages.
2789 See Documentation/vm/transhuge.txt for more details.
2791 tsc= Disable clocksource stability checks for TSC.
2793 [x86] reliable: mark tsc clocksource as reliable, this
2794 disables clocksource verification at runtime, as well
2795 as the stability checks done at bootup. Used to enable
2796 high-resolution timer mode on older hardware, and in
2797 virtualized environment.
2798 [x86] noirqtime: Do not use TSC to do irq accounting.
2799 Used to run time disable IRQ_TIME_ACCOUNTING on any
2800 platforms where RDTSC is slow and this accounting
2803 turbografx.map[2|3]= [HW,JOY]
2804 TurboGraFX parallel port interface
2806 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2807 See also Documentation/input/joystick-parport.txt
2809 udbg-immortal [PPC] When debugging early kernel crashes that
2810 happen after console_init() and before a proper
2811 console driver takes over, this boot options might
2812 help "seeing" what's going on.
2814 uhash_entries= [KNL,NET]
2815 Set number of hash buckets for UDP/UDP-Lite connections
2818 [USB] Ignore overcurrent events (default N).
2819 Some badly-designed motherboards generate lots of
2820 bogus events, for ports that aren't wired to
2821 anything. Set this parameter to avoid log spamming.
2822 Note that genuine overcurrent events won't be
2826 [X86] Cause panic on unknown NMI.
2828 usbcore.authorized_default=
2829 [USB] Default USB device authorization:
2830 (default -1 = authorized except for wireless USB,
2831 0 = not authorized, 1 = authorized)
2833 usbcore.autosuspend=
2834 [USB] The autosuspend time delay (in seconds) used
2835 for newly-detected USB devices (default 2). This
2836 is the time required before an idle device will be
2837 autosuspended. Devices for which the delay is set
2838 to a negative value won't be autosuspended at all.
2840 usbcore.usbfs_snoop=
2841 [USB] Set to log all usbfs traffic (default 0 = off).
2843 usbcore.blinkenlights=
2844 [USB] Set to cycle leds on hubs (default 0 = off).
2846 usbcore.old_scheme_first=
2847 [USB] Start with the old device initialization
2848 scheme (default 0 = off).
2850 usbcore.usbfs_memory_mb=
2851 [USB] Memory limit (in MB) for buffers allocated by
2852 usbfs (default = 16, 0 = max = 2047).
2854 usbcore.use_both_schemes=
2855 [USB] Try the other device initialization scheme
2856 if the first one fails (default 1 = enabled).
2858 usbcore.initial_descriptor_timeout=
2859 [USB] Specifies timeout for the initial 64-byte
2860 USB_REQ_GET_DESCRIPTOR request in milliseconds
2861 (default 5000 = 5.0 seconds).
2864 [USBHID] The interval which mice are to be polled at.
2866 usb-storage.delay_use=
2867 [UMS] The delay in seconds before a new device is
2868 scanned for Logical Units (default 5).
2871 [UMS] A list of quirks entries to supplement or
2872 override the built-in unusual_devs list. List
2873 entries are separated by commas. Each entry has
2874 the form VID:PID:Flags where VID and PID are Vendor
2875 and Product ID values (4-digit hex numbers) and
2876 Flags is a set of characters, each corresponding
2877 to a common usb-storage quirk flag as follows:
2878 a = SANE_SENSE (collect more than 18 bytes
2880 b = BAD_SENSE (don't collect more than 18
2881 bytes of sense data);
2882 c = FIX_CAPACITY (decrease the reported
2883 device capacity by one sector);
2884 d = NO_READ_DISC_INFO (don't use
2885 READ_DISC_INFO command);
2886 e = NO_READ_CAPACITY_16 (don't use
2887 READ_CAPACITY_16 command);
2888 h = CAPACITY_HEURISTICS (decrease the
2889 reported device capacity by one
2890 sector if the number is odd);
2891 i = IGNORE_DEVICE (don't bind to this
2893 l = NOT_LOCKABLE (don't try to lock and
2894 unlock ejectable media);
2895 m = MAX_SECTORS_64 (don't transfer more
2896 than 64 sectors = 32 KB at a time);
2897 n = INITIAL_READ10 (force a retry of the
2898 initial READ(10) command);
2899 o = CAPACITY_OK (accept the capacity
2900 reported by the device);
2901 r = IGNORE_RESIDUE (the device reports
2902 bogus residue values);
2903 s = SINGLE_LUN (the device has only one
2905 w = NO_WP_DETECT (don't test whether the
2906 medium is write-protected).
2907 Example: quirks=0419:aaf5:rl,0421:0433:rc
2909 user_debug= [KNL,ARM]
2911 See arch/arm/Kconfig.debug help text.
2912 1 - undefined instruction events
2914 4 - invalid data aborts
2917 Example: user_debug=31
2920 [X86] Flags controlling user PTE allocations.
2922 nohigh = do not allocate PTE pages in
2923 HIGHMEM regardless of setting
2927 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2928 vdso=1: enable VDSO (default)
2929 vdso=0: disable VDSO mapping
2932 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2933 vdso32=1: enable 32-bit VDSO (default)
2934 vdso32=0: disable 32-bit VDSO mapping
2937 vector=percpu: enable percpu vector domain
2939 video= [FB] Frame buffer configuration
2940 See Documentation/fb/modedb.txt.
2943 [VMMIO] Memory mapped virtio (platform) device.
2945 <size>@<baseaddr>:<irq>[:<id>]
2947 <size> := size (can use standard suffixes
2949 <baseaddr> := physical base address
2950 <irq> := interrupt number (as passed to
2952 <id> := (optional) platform device id
2954 virtio_mmio.device=1K@0x100b0000:48:7
2956 Can be used multiple times for multiple devices.
2958 vga= [BOOT,X86-32] Select a particular video mode
2959 See Documentation/x86/boot.txt and
2960 Documentation/svga.txt.
2961 Use vga=ask for menu.
2962 This is actually a boot loader parameter; the value is
2963 passed to the kernel using a special protocol.
2965 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2966 size of <nn>. This can be used to increase the
2967 minimum size (128MB on x86). It can also be used to
2968 decrease the size and leave more room for directly
2971 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2974 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2977 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2981 Controls the behavior of vsyscalls (i.e. calls to
2982 fixed addresses of 0xffffffffff600x00 from legacy
2983 code). Most statically-linked binaries and older
2984 versions of glibc use these calls. Because these
2985 functions are at fixed addresses, they make nice
2986 targets for exploits that can control RIP.
2988 emulate [default] Vsyscalls turn into traps and are
2989 emulated reasonably safely.
2991 native Vsyscalls are native syscall instructions.
2992 This is a little bit faster than trapping
2993 and makes a few dynamic recompilers work
2994 better than they would in emulation mode.
2995 It also makes exploits much easier to write.
2997 none Vsyscalls don't work at all. This makes
2998 them quite hard to use for exploits but
2999 might break your system.
3001 vt.cur_default= [VT] Default cursor shape.
3002 Format: 0xCCBBAA, where AA, BB, and CC are the same as
3003 the parameters of the <Esc>[?A;B;Cc escape sequence;
3004 see VGA-softcursor.txt. Default: 2 = underline.
3006 vt.default_blu= [VT]
3007 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3008 Change the default blue palette of the console.
3009 This is a 16-member array composed of values
3012 vt.default_grn= [VT]
3013 Format: <green0>,<green1>,<green2>,...,<green15>
3014 Change the default green palette of the console.
3015 This is a 16-member array composed of values
3018 vt.default_red= [VT]
3019 Format: <red0>,<red1>,<red2>,...,<red15>
3020 Change the default red palette of the console.
3021 This is a 16-member array composed of values
3027 Set system-wide default UTF-8 mode for all tty's.
3028 Default is 1, i.e. UTF-8 mode is enabled for all
3029 newly opened terminals.
3031 vt.global_cursor_default=
3034 Set system-wide default for whether a cursor
3035 is shown on new VTs. Default is -1,
3036 i.e. cursors will be created by default unless
3037 overridden by individual drivers. 0 will hide
3038 cursors, 1 will display them.
3040 watchdog timers [HW,WDT] For information on watchdog timers,
3041 see Documentation/watchdog/watchdog-parameters.txt
3042 or other driver-specific files in the
3043 Documentation/watchdog/ directory.
3045 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
3046 default x2apic cluster mode on platforms
3049 x86_mrst_timer= [X86-32,APBT]
3050 Choose timer option for x86 Moorestown MID platform.
3051 Two valid options are apbt timer only and lapic timer
3052 plus one apbt timer for broadcast timer.
3053 x86_mrst_timer=apbt_only | lapic_and_apbt
3055 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
3056 xd_geo= See header of drivers/block/xd.c.
3058 xen_emul_unplug= [HW,X86,XEN]
3059 Unplug Xen emulated devices
3060 Format: [unplug0,][unplug1]
3061 ide-disks -- unplug primary master IDE devices
3062 aux-ide-disks -- unplug non-primary-master IDE devices
3063 nics -- unplug network devices
3064 all -- unplug all emulated devices (NICs and IDE disks)
3065 unnecessary -- unplugging emulated devices is
3066 unnecessary even if the host did not respond to
3068 never -- do not unplug even if version check succeeds
3070 xirc2ps_cs= [NET,PCMCIA]
3072 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
3074 ______________________________________________________________________
3078 Add more DRM drivers.
git.samba.org / sfrench / cifs-2.6.git / blob