4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 ARM ARM architecture is enabled.
44 AVR32 AVR32 architecture is enabled.
45 AX25 Appropriate AX.25 support is enabled.
46 BLACKFIN Blackfin architecture is enabled.
47 DRM Direct Rendering Management support is enabled.
48 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
49 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
50 EFI EFI Partitioning (GPT) is enabled
51 EIDE EIDE/ATAPI support is enabled.
52 EVM Extended Verification Module
53 FB The frame buffer device is enabled.
54 FTRACE Function tracing enabled.
55 GCOV GCOV profiling is enabled.
56 HW Appropriate hardware is enabled.
57 IA-64 IA-64 architecture is enabled.
58 IMA Integrity measurement architecture is enabled.
59 IOSCHED More than one I/O scheduler is enabled.
60 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
61 IPV6 IPv6 support is enabled.
62 ISAPNP ISA PnP code is enabled.
63 ISDN Appropriate ISDN support is enabled.
64 JOY Appropriate joystick support is enabled.
65 KGDB Kernel debugger support is enabled.
66 KVM Kernel Virtual Machine support is enabled.
67 LIBATA Libata driver is enabled
68 LP Printer support is enabled.
69 LOOP Loopback device support is enabled.
70 M68k M68k architecture is enabled.
71 These options have more detailed description inside of
72 Documentation/m68k/kernel-options.txt.
73 MCA MCA bus support is enabled.
74 MDA MDA console support is enabled.
75 MIPS MIPS architecture is enabled.
76 MOUSE Appropriate mouse support is enabled.
77 MSI Message Signaled Interrupts (PCI).
78 MTD MTD (Memory Technology Device) support is enabled.
79 NET Appropriate network support is enabled.
80 NUMA NUMA support is enabled.
81 NFS Appropriate NFS support is enabled.
82 OSS OSS sound support is enabled.
83 PV_OPS A paravirtualized kernel is enabled.
84 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
85 PARISC The PA-RISC architecture is enabled.
86 PCI PCI bus support is enabled.
87 PCIE PCI Express support is enabled.
88 PCMCIA The PCMCIA subsystem is enabled.
89 PNP Plug & Play support is enabled.
90 PPC PowerPC architecture is enabled.
91 PPT Parallel port support is enabled.
92 PS2 Appropriate PS/2 support is enabled.
93 RAM RAM disk support is enabled.
94 S390 S390 architecture is enabled.
95 SCSI Appropriate SCSI support is enabled.
96 A lot of drivers have their options described inside
97 the Documentation/scsi/ sub-directory.
98 SECURITY Different security models are enabled.
99 SELINUX SELinux support is enabled.
100 APPARMOR AppArmor support is enabled.
101 SERIAL Serial support is enabled.
102 SH SuperH architecture is enabled.
103 SMP The kernel is an SMP kernel.
104 SPARC Sparc architecture is enabled.
105 SWSUSP Software suspend (hibernation) is enabled.
106 SUSPEND System suspend states are enabled.
107 TPM TPM drivers are enabled.
108 TS Appropriate touchscreen support is enabled.
109 UMS USB Mass Storage support is enabled.
110 USB USB support is enabled.
111 USBHID USB Human Interface Device support is enabled.
112 V4L Video For Linux support is enabled.
113 VGA The VGA console has been enabled.
114 VT Virtual terminal support is enabled.
115 WDT Watchdog support is enabled.
116 XT IBM PC/XT MFM hard disk support is enabled.
117 X86-32 X86-32, aka i386 architecture is enabled.
118 X86-64 X86-64 architecture is enabled.
119 More X86-64 boot options can be found in
120 Documentation/x86/x86_64/boot-options.txt .
121 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
122 XEN Xen support is enabled
124 In addition, the following text indicates that the option:
126 BUGS= Relates to possible processor bugs on the said processor.
127 KNL Is a kernel start-up parameter.
128 BOOT Is a boot loader parameter.
130 Parameters denoted with BOOT are actually interpreted by the boot
131 loader, and have no meaning to the kernel directly.
132 Do not modify the syntax of boot loader parameters without extreme
133 need or coordination with <Documentation/x86/boot.txt>.
135 There are also arch-specific kernel-parameters not documented here.
136 See for example <Documentation/x86/x86_64/boot-options.txt>.
138 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139 a trailing = on the name of any parameter states that that parameter will
140 be entered as an environment variable, whereas its absence indicates that
141 it will appear as a kernel argument readable via /proc/cmdline by programs
142 running once the system is up.
144 The number of kernel parameters is not limited, but the length of the
145 complete command line (parameters including spaces etc.) is limited to
146 a fixed number of characters. This limit depends on the architecture
147 and is between 256 and 4096 characters. It is defined in the file
148 ./include/asm/setup.h as COMMAND_LINE_SIZE.
150 Finally, the [KMG] suffix is commonly described after a number of kernel
151 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153 bytes respectively. Such letter suffixes can also be entirely omitted.
157 Advanced Configuration and Power Interface
158 Format: { force | off | strict | noirq | rsdt }
159 force -- enable ACPI if default was off
160 off -- disable ACPI if default was on
161 noirq -- do not use ACPI for IRQ routing
162 strict -- Be less tolerant of platforms that are not
163 strictly ACPI specification compliant.
164 rsdt -- prefer RSDT over (default) XSDT
165 copy_dsdt -- copy DSDT to memory
167 See also Documentation/power/runtime_pm.txt, pci=noacpi
169 acpi_rsdp= [ACPI,EFI,KEXEC]
170 Pass the RSDP address to the kernel, mostly used
171 on machines running EFI runtime service to boot the
172 second kernel for kdump.
174 acpi_apic_instance= [ACPI, IOAPIC]
176 2: use 2nd APIC table, if available
177 1,0: use 1st APIC table
180 acpi_backlight= [HW,ACPI]
181 acpi_backlight=vendor
183 If set to vendor, prefer vendor specific driver
184 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
185 of the ACPI video.ko driver.
187 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
188 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
190 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191 debug output. Bits in debug_layer correspond to a
192 _COMPONENT in an ACPI source file, e.g.,
193 #define _COMPONENT ACPI_PCI_COMPONENT
194 Bits in debug_level correspond to a level in
195 ACPI_DEBUG_PRINT statements, e.g.,
196 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
197 The debug_level mask defaults to "info". See
198 Documentation/acpi/debug.txt for more information about
199 debug layers and levels.
201 Enable processor driver info messages:
202 acpi.debug_layer=0x20000000
203 Enable PCI/PCI interrupt routing info messages:
204 acpi.debug_layer=0x400000
205 Enable AML "Debug" output, i.e., stores to the Debug
206 object while interpreting AML:
207 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
208 Enable all messages related to ACPI hardware:
209 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
211 Some values produce so much output that the system is
212 unusable. The "log_buf_len" parameter may be useful
213 if you need to capture more output.
215 acpi_irq_balance [HW,ACPI]
216 ACPI will balance active IRQs
219 acpi_irq_nobalance [HW,ACPI]
220 ACPI will not move active IRQs (default)
223 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224 Format: <irq>,<irq>...
226 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
228 Format: <irq>,<irq>...
230 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
232 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
233 Format: To spoof as Windows 98: ="Microsoft Windows"
235 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
236 acpi_osi="string1" # add string1 -- only one string
237 acpi_osi="!string2" # remove built-in string2
238 acpi_osi= # disable all strings
241 Override the pmtimer bug detection: force the kernel
242 to assume that this machine's pmtimer latches its value
243 and always returns good values.
245 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
246 Format: { level | edge | high | low }
248 acpi_serialize [HW,ACPI] force serialization of AML methods
250 acpi_skip_timer_override [HW,ACPI]
251 Recognize and ignore IRQ0/pin2 Interrupt Override.
252 For broken nForce2 BIOS resulting in XT-PIC timer.
254 acpi_sleep= [HW,ACPI] Sleep options
255 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
256 old_ordering, nonvs, sci_force_enable }
257 See Documentation/power/video.txt for information on
259 s3_beep is for debugging; it makes the PC's speaker beep
260 as soon as the kernel's real-mode entry point is called.
261 s4_nohwsig prevents ACPI hardware signature from being
262 used during resume from hibernation.
263 old_ordering causes the ACPI 1.0 ordering of the _PTS
264 control method, with respect to putting devices into
265 low power states, to be enforced (the ACPI 2.0 ordering
266 of _PTS is used by default).
267 nonvs prevents the kernel from saving/restoring the
268 ACPI NVS memory during suspend/hibernation and resume.
269 sci_force_enable causes the kernel to set SCI_EN directly
270 on resume from S1/S3 (which is against the ACPI spec,
271 but some broken systems don't work without it).
273 acpi_use_timer_override [HW,ACPI]
274 Use timer override. For some broken Nvidia NF5 boards
275 that require a timer override, but don't have HPET
277 acpi_enforce_resources= [ACPI]
278 { strict | lax | no }
279 Check for resource conflicts between native drivers
280 and ACPI OperationRegions (SystemIO and SystemMemory
281 only). IO ports and memory declared in ACPI might be
282 used by the ACPI subsystem in arbitrary AML code and
283 can interfere with legacy drivers.
284 strict (default): access to resources claimed by ACPI
285 is denied; legacy drivers trying to access reserved
286 resources will fail to bind to device using them.
287 lax: access to resources claimed by ACPI is allowed;
288 legacy drivers trying to access reserved resources
289 will bind successfully but a warning message is logged.
290 no: ACPI OperationRegions are not marked as reserved,
291 no further checks are performed.
293 add_efi_memmap [EFI; X86] Include EFI memory map in
294 kernel's map of available physical RAM.
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
303 See Documentation/sound/alsa/alsa-parameters.txt
306 Allow the default userspace alignment fault handler
307 behaviour to be specified. Bit 0 enables warnings,
308 bit 1 enables fixups, and bit 2 sends a segfault.
310 align_va_addr= [X86-64]
311 Align virtual addresses by clearing slice [14:12] when
312 allocating a VMA at process creation time. This option
313 gives you up to 3% performance improvement on AMD F15h
314 machines (where it is enabled by default) for a
315 CPU-intensive style benchmark, and it can vary highly in
316 a microbenchmark depending on workload and compiler.
318 32: only for 32-bit processes
319 64: only for 64-bit processes
320 on: enable for both 32- and 64-bit processes
321 off: disable for both 32- and 64-bit processes
323 amd_iommu= [HW,X86-64]
324 Pass parameters to the AMD IOMMU driver in the system.
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
330 off - do not initialize any AMD IOMMU found in
333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
336 See also Documentation/input/joystick.txt
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
344 Power management functions (SPARCstation-4/5 + deriv.)
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
351 Change the output verbosity whilst booting
352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
357 See Documentation/networking/ipv6.txt.
359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
368 apm= [APM] Advanced Power Management
369 See header of arch/x86/kernel/apm_32.c.
371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
376 atarimouse= [HW,MOUSE] Atari Mouse
378 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
379 EzKey and similar keyboards
381 atkbd.reset= [HW] Reset keyboard during initialization
383 atkbd.set= [HW] Select keyboard code set
384 Format: <int> (2 = AT (default), 3 = PS/2)
386 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 atkbd.softraw= [HW] Choose between synthetic and real raw mode
390 Format: <bool> (0 = real, 1 = synthetic (default))
392 atkbd.softrepeat= [HW]
393 Use software keyboard repeat
397 baycom_epp= [HW,AX25]
400 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
402 See header of drivers/net/hamradio/baycom_par.c.
404 baycom_ser_fdx= [HW,AX25]
405 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
406 Format: <io>,<irq>,<mode>[,<baud>]
407 See header of drivers/net/hamradio/baycom_ser_fdx.c.
409 baycom_ser_hdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
411 Format: <io>,<irq>,<mode>
412 See header of drivers/net/hamradio/baycom_ser_hdx.c.
414 boot_delay= Milliseconds to delay each printk during boot.
415 Values larger than 10 seconds (10000) are changed to
419 bootmem_debug [KNL] Enable bootmem allocator debug messages.
421 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
422 bttv.radio= Most important insmod options are available as
424 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bulk_remove=off [PPC] This parameter disables the use of the pSeries
428 firmware feature for flushing multiple hpte entries
431 c101= [NET] Moxa C101 synchronous serial card
433 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
434 Sometimes CPU hardware bugs make them report the cache
435 size incorrectly. The kernel will attempt work arounds
436 to fix known problems, but for some CPUs it is not
437 possible to determine what the correct size should be.
438 This option provides an override for these situations.
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
460 Value can be changed at runtime via
461 /selinux/checkreqprot.
464 See Documentation/s390/CommonIO for details.
466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
468 Forces specified clocksource (if available) to be used
469 when calculating gettimeofday(). If specified
470 clocksource is not available, it defaults to PIT.
471 Format: { pit | tsc | cyclone | pmtmr }
473 clocksource= Override the default clocksource
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
479 [all] jiffies (this is the base, fallback clocksource)
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
484 [X86-32] pit,hpet,tsc;
485 scx200_hrt on Geode; cyclone on IBM x440
493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
495 arch/x86/include/asm/cpufeature.h for the valid bit
496 numbers. Note the Linux specific bits are not necessarily
497 stable over kernel options, but the vendor specific
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
507 Sets the size of kernel global memory area for contiguous
508 memory allocations. For more information, see
509 include/linux/dma-contiguous.h
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 coherent_pool=nn[KMG] [ARM,KNL]
519 Sets the size of memory pool for coherent, atomic dma
520 allocations if Contiguous Memory Allocator (CMA) is used.
522 code_bytes [X86] How many bytes of object code to print
527 com20020= [HW,NET] ARCnet - COM20020 chipset
529 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
531 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
535 ARCnet - COM90xx chipset (memory-mapped buffers)
536 Format: <io>[,<irq>[,<memstart>]]
538 condev= [HW,S390] console device
541 console= [KNL] Output console device and options.
543 tty<n> Use the virtual console device <n>.
547 Use the specified serial port. The options are of
548 the form "bbbbpnf", where "bbbb" is the baud rate,
549 "p" is parity ("n", "o", or "e"), "n" is number of
550 bits, and "f" is flow control ("r" for RTS or
551 omit it). Default is "9600n8".
553 See Documentation/serial-console.txt for more
555 Documentation/networking/netconsole.txt for an
558 uart[8250],io,<addr>[,options]
559 uart[8250],mmio,<addr>[,options]
560 Start an early, polled-mode console on the 8250/16550
561 UART at the specified I/O port or MMIO address,
562 switching to the matching ttyS device later. The
563 options are the same as for ttyS, above.
564 hvc<n> Use the hypervisor console device <n>. This is for
565 both Xen and PowerPC hypervisors.
567 If the device connected to the port is not a TTY but a braille
568 device, prepend "brl," before the device type, for instance
570 For now, only VisioBraille is supported.
572 consoleblank= [KNL] The console blank (screen saver) timeout in
573 seconds. Defaults to 10*60 = 10mins. A value of 0
574 disables the blank timer.
577 [KNL] Change the default value for
578 /proc/<pid>/coredump_filter.
579 See also Documentation/filesystems/proc.txt.
581 cpuidle.off=1 [CPU_IDLE]
582 disable the cpuidle sub-system
584 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
586 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
588 crashkernel=size[KMG][@offset[KMG]]
589 [KNL] Using kexec, Linux can switch to a 'crash kernel'
590 upon panic. This parameter reserves the physical
591 memory region [offset, offset + size] for that kernel
592 image. If '@offset' is omitted, then a suitable offset
593 is selected automatically. Check
594 Documentation/kdump/kdump.txt for further details.
596 crashkernel=range1:size1[,range2:size2,...][@offset]
597 [KNL] Same as above, but depends on the memory
598 in the running system. The syntax of range is
599 start-[end] where start and end are both
600 a memory unit (amount[KMG]). See also
601 Documentation/kdump/kdump.txt for an example.
606 cs89x0_media= [HW,NET]
607 Format: { rj45 | aui | bnc }
610 See header of drivers/s390/block/dasd_devmap.c.
612 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
613 (one device per port)
614 Format: <port#>,<type>
615 See also Documentation/input/joystick-parport.txt
617 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
618 time. See Documentation/dynamic-debug-howto.txt for
621 debug [KNL] Enable kernel debugging (events log level).
624 [KNL] verbose self-tests
626 Print debugging info while doing the locking API
628 We default to 0 (no extra messages), setting it to
629 1 will print _a lot_ more information - normally
630 only useful to kernel developers.
632 debug_objects [KNL] Enable object debugging
635 [KNL] Disable object debugging
637 debug_guardpage_minorder=
638 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
639 parameter allows control of the order of pages that will
640 be intentionally kept free (and hence protected) by the
641 buddy allocator. Bigger value increase the probability
642 of catching random memory corruption, but reduce the
643 amount of memory for normal system use. The maximum
644 possible value is MAX_ORDER/2. Setting this parameter
645 to 1 or 2 should be enough to identify most random
646 memory corruption problems caused by bugs in kernel or
647 driver code when a CPU writes to (or reads from) a
648 random memory location. Note that there exists a class
649 of memory corruptions problems caused by buggy H/W or
650 F/W or by drivers badly programing DMA (basically when
651 memory is written at bus level and the CPU MMU is
652 bypassed) which are not detectable by
653 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
654 tracking down these problems.
656 debugpat [X86] Enable PAT debugging
658 decnet.addr= [HW,NET]
659 Format: <area>[,<node>]
660 See also Documentation/networking/decnet.txt.
663 [same as hugepagesz=] The size of the default
664 HugeTLB page size. This is the size represented by
665 the legacy /proc/ hugepages APIs, used for SHM, and
666 default size when mounting hugetlbfs filesystems.
667 Defaults to the default architecture's huge page size
671 Set number of hash buckets for dentry cache.
674 IO parameters + enable/disable command.
676 digiepca= [HW,SERIAL]
677 See drivers/char/README.epca and
678 Documentation/serial/digiepca.txt.
681 See Documentation/networking/ipv6.txt.
683 disable_ddw [PPC/PSERIES]
684 Disable Dynamic DMA Window support. Use this if
685 to workaround buggy firmware.
688 See Documentation/networking/ipv6.txt.
690 disable_mtrr_cleanup [X86]
691 The kernel tries to adjust MTRR layout from continuous
692 to discrete, to make X server driver able to add WB
693 entry later. This parameter disables that.
695 disable_mtrr_trim [X86, Intel and AMD only]
696 By default the kernel will trim any uncacheable
697 memory out of your available memory pool based on
698 MTRR settings. This parameter disables that behavior,
699 possibly causing your machine to run very slowly.
701 disable_timer_pin_1 [X86]
702 Disable PIN 1 of APIC timer
703 Can be useful to work around chipset bugs.
705 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
706 this option disables the debugging code at boot.
708 dma_debug_entries=<number>
709 This option allows to tune the number of preallocated
710 entries for DMA-API debugging code. One entry is
711 required per DMA-API allocation. Use this if the
712 DMA-API debugging code disables itself because the
713 architectural default is too low.
715 dma_debug_driver=<driver_name>
716 With this option the DMA-API debugging driver
717 filter feature can be enabled at boot time. Just
718 pass the driver to filter for as the parameter.
719 The filter can be disabled or changed to another
720 driver later using sysfs.
724 earlycon= [KNL] Output early console device and options.
725 uart[8250],io,<addr>[,options]
726 uart[8250],mmio,<addr>[,options]
727 uart[8250],mmio32,<addr>[,options]
728 Start an early, polled-mode console on the 8250/16550
729 UART at the specified I/O port or MMIO address.
730 MMIO inter-register address stride is either 8-bit
731 (mmio) or 32-bit (mmio32).
732 The options are the same as for ttyS, above.
734 earlyprintk= [X86,SH,BLACKFIN]
737 earlyprintk=serial[,ttySn[,baudrate]]
738 earlyprintk=ttySn[,baudrate]
739 earlyprintk=dbgp[debugController#]
741 Append ",keep" to not disable it when the real console
744 Only vga or serial or usb debug port at a time.
746 Currently only ttyS0 and ttyS1 are supported.
748 Interaction with the standard serial driver is not
751 The VGA output is eventually overwritten by the real
754 The xen output can only be used by Xen PV guests.
756 ekgdboc= [X86,KGDB] Allow early kernel console debugging
759 This is designed to be used in conjunction with
760 the boot argument: earlyprintk=vga
763 Format: {"off" | "on" | "skip[mbr]"}
765 eisa_irq_edge= [PARISC,HW]
766 See header of drivers/parisc/eisa.c.
769 See comment before function elanfreq_setup() in
770 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
773 Format: {"cfq" | "deadline" | "noop"}
774 See Documentation/block/cfq-iosched.txt and
775 Documentation/block/deadline-iosched.txt for details.
777 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
778 Specifies physical address of start of kernel core
779 image elf header and optionally the size. Generally
780 kexec loader will pass this option to capture kernel.
781 See Documentation/kdump/kdump.txt for details.
783 enable_mtrr_cleanup [X86]
784 The kernel tries to adjust MTRR layout from continuous
785 to discrete, to make X server driver able to add WB
786 entry later. This parameter enables that.
788 enable_timer_pin_1 [X86]
789 Enable PIN 1 of APIC timer
790 Can be useful to work around chipset bugs
791 (in particular on some ATI chipsets).
792 The kernel tries to set a reasonable default.
794 enforcing [SELINUX] Set initial enforcing status.
796 See security/selinux/Kconfig help text.
797 0 -- permissive (log only, no denials).
798 1 -- enforcing (deny and log).
800 Value can be changed at runtime via /selinux/enforce.
803 Disable Error Record Serialization Table (ERST)
806 ether= [HW,NET] Ethernet cards parameters
807 This option is obsoleted by the "netdev=" option, which
808 has equivalent usage. See its documentation for details.
812 Permit 'security.evm' to be updated regardless of
813 current integrity status.
817 fail_make_request=[KNL]
818 General fault injection mechanism.
819 Format: <interval>,<probability>,<space>,<times>
820 See also Documentation/fault-injection/.
823 See Documentation/blockdev/floppy.txt.
825 force_pal_cache_flush
826 [IA-64] Avoid check_sal_cache_flush which may hang on
827 buggy SAL_CACHE_FLUSH implementations. Using this
828 parameter will force ia64_sal_cache_flush to call
829 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
832 [FTRACE] will set and start the specified tracer
833 as early as possible in order to facilitate early
836 ftrace_dump_on_oops[=orig_cpu]
837 [FTRACE] will dump the trace buffers on oops.
838 If no parameter is passed, ftrace will dump
839 buffers of all CPUs, but if you pass orig_cpu, it will
840 dump only the buffer of the CPU that triggered the
843 ftrace_filter=[function-list]
844 [FTRACE] Limit the functions traced by the function
845 tracer at boot up. function-list is a comma separated
846 list of functions. This list can be changed at run
847 time by the set_ftrace_filter file in the debugfs
850 ftrace_notrace=[function-list]
851 [FTRACE] Do not trace the functions specified in
852 function-list. This list can be changed at run time
853 by the set_ftrace_notrace file in the debugfs
856 ftrace_graph_filter=[function-list]
857 [FTRACE] Limit the top level callers functions traced
858 by the function graph tracer at boot up.
859 function-list is a comma separated list of functions
860 that can be changed at run time by the
861 set_graph_function file in the debugfs tracing directory.
864 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
865 support via parallel port (up to 5 devices per port)
866 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
867 See also Documentation/input/joystick-parport.txt
871 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
875 gcov_persist= [GCOV] When non-zero (default), profiling data for
876 kernel modules is saved and remains accessible via
877 debugfs, even when the module is unloaded/reloaded.
878 When zero, profiling data is discarded and associated
879 debugfs files are removed at module unload time.
881 gpt [EFI] Forces disk with valid GPT signature but
882 invalid Protective MBR to be treated as GPT.
884 hashdist= [KNL,NUMA] Large hashes allocated during boot
885 are distributed across NUMA nodes. Defaults on
886 for 64-bit NUMA, off otherwise.
887 Format: 0 | 1 (for off | on)
889 hcl= [IA-64] SGI's Hardware Graph compatibility layer
891 hd= [EIDE] (E)IDE hard drive subsystem geometry
892 Format: <cyl>,<head>,<sect>
895 Disable Hardware Error Source Table (HEST) support;
896 corresponding firmware-first mode error processing
897 logic will be disabled.
899 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
900 size of <nn>. This works even on boxes that have no
901 highmem otherwise. This also works to reduce highmem
902 size on bigger boxes.
904 highres= [KNL] Enable/disable high resolution timer mode.
905 Valid parameters: "on", "off"
909 See Documentation/isdn/README.HiSax.
913 hpet= [X86-32,HPET] option to control HPET usage
914 Format: { enable (default) | disable | force |
916 disable: disable HPET and use PIT instead
917 force: allow force enabled of undocumented chips (ICH4,
919 verbose: show contents of HPET registers during setup
921 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
922 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
923 On x86-64 and powerpc, this option can be specified
924 multiple times interleaved with hugepages= to reserve
925 huge pages of different sizes. Valid pages sizes on
926 x86-64 are 2M (when the CPU supports "pse") and 1G
927 (when the CPU supports the "pdpe1gb" cpuinfo flag)
928 Note that 1GB pages can only be allocated at boot time
929 using hugepages= and not freed afterwards.
931 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
932 terminal devices. Valid values: 0..8
933 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
934 If specified, z/VM IUCV HVC accepts connections
935 from listed z/VM user IDs only.
938 Do not unregister boot console at start. This is only
939 useful for debugging when something happens in the window
940 between unregistering the boot console and initializing
943 i2c_bus= [HW] Override the default board specific I2C bus speed
944 or register an additional I2C bus that is not
945 registered from board initialization code.
949 i8042.debug [HW] Toggle i8042 debug mode
950 i8042.direct [HW] Put keyboard port into non-translated mode
951 i8042.dumbkbd [HW] Pretend that controller can only read data from
952 keyboard and cannot control its state
953 (Don't attempt to blink the leds)
954 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
955 i8042.nokbd [HW] Don't check/create keyboard port
956 i8042.noloop [HW] Disable the AUX Loopback command while probing
958 i8042.nomux [HW] Don't check presence of an active multiplexing
960 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
962 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
963 i8042.reset [HW] Reset the controller during init and cleanup
964 i8042.unlock [HW] Unlock (ignore) the keylock
968 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
969 indicates that the driver is running on unsupported
971 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
972 does not match list of supported models.
974 [HW] Report power status in /proc/i8k
975 (disabled by default)
976 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
979 i915.invert_brightness=
980 [DRM] Invert the sense of the variable that is used to
981 set the brightness of the panel backlight. Normally a
982 brightness value of 0 indicates backlight switched off,
983 and the maximum of the brightness value sets the backlight
984 to maximum brightness. If this parameter is set to 0
985 (default) and the machine requires it, or this parameter
986 is set to 1, a brightness value of 0 sets the backlight
987 to maximum brightness, and the maximum of the brightness
988 value switches the backlight off.
989 -1 -- never invert brightness
991 1 -- force brightness inversion
994 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
996 ide-core.nodma= [HW] (E)IDE subsystem
997 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
998 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
999 .cdrom .chs .ignore_cable are additional options
1000 See Documentation/ide/ide.txt.
1002 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1003 Claim all unknown PCI IDE storage controllers.
1006 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
1007 Poll forces a polling idle loop that can slightly
1008 improve the performance of waking up a idle CPU, but
1009 will use a lot of power and make the system run hot.
1011 idle=mwait: On systems which support MONITOR/MWAIT but
1012 the kernel chose to not use it because it doesn't save
1013 as much power as a normal idle loop, use the
1014 MONITOR/MWAIT idle loop anyways. Performance should be
1015 the same as idle=poll.
1016 idle=halt: Halt is forced to be used for CPU idle.
1017 In such case C2/C3 won't be used again.
1018 idle=nomwait: Disable mwait for CPU C-states
1020 ignore_loglevel [KNL]
1021 Ignore loglevel setting - this will print /all/
1022 kernel messages to the console. Useful for debugging.
1023 We also add it as printk module parameter, so users
1024 could change it dynamically, usually by
1025 /sys/module/printk/parameters/ignore_loglevel.
1027 ihash_entries= [KNL]
1028 Set number of hash buckets for inode cache.
1031 Format: { "0" | "1" }
1032 0 -- integrity auditing messages. (Default)
1033 1 -- enable informational integrity auditing messages.
1036 Format: { "sha1" | "md5" }
1040 Load a policy which meets the needs of the Trusted
1041 Computing Base. This means IMA will measure all
1042 programs exec'd, files mmap'd for exec, and all files
1043 opened for read by uid=0.
1047 Run specified binary instead of /sbin/init as init
1050 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1051 for working out where the kernel is dying during
1054 initrd= [BOOT] Specify the location of the initial ramdisk
1056 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1059 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1061 Enable intel iommu driver.
1063 Disable intel iommu driver.
1064 igfx_off [Default Off]
1065 By default, gfx is mapped as normal device. If a gfx
1066 device has a dedicated DMAR unit, the DMAR unit is
1067 bypassed by not enabling DMAR with this option. In
1068 this case, gfx device will use physical address for
1071 With this option iommu will not optimize to look
1072 for io virtual address below 32-bit forcing dual
1073 address cycle on pci bus for cards supporting greater
1074 than 32-bit addressing. The default is to look
1075 for translation below 32-bit and if not available
1076 then look in the higher range.
1077 strict [Default Off]
1078 With this option on every unmap_single operation will
1079 result in a hardware IOTLB flush operation as opposed
1080 to batching them for performance.
1081 sp_off [Default Off]
1082 By default, super page will be supported if Intel IOMMU
1083 has the capability. With this option, super page will
1085 intremap= [X86-64, Intel-IOMMU]
1086 on enable Interrupt Remapping (default)
1087 off disable Interrupt Remapping
1088 nosid disable Source ID checking
1090 BIOS x2APIC opt-out request will be ignored
1094 iomem= Disable strict checking of access to MMIO memory
1095 strict regions from userspace.
1111 io7= [HW] IO7 for Marvel based alpha systems
1112 See comment before marvel_specify_io7 in
1113 arch/alpha/kernel/core_marvel.c.
1115 io_delay= [X86] I/O delay method
1117 Standard port 0x80 based delay
1119 Alternate port 0xed based delay (needed on some systems)
1121 Simple two microseconds delay
1126 See Documentation/filesystems/nfs/nfsroot.txt.
1128 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1129 See comment before ip2_setup() in
1130 drivers/char/ip2/ip2base.c.
1133 When an interrupt is not handled search all handlers
1134 for it. Intended to get systems with badly broken
1138 When an interrupt is not handled search all handlers
1139 for it. Also check all handlers each timer
1140 interrupt. Intended to get systems with badly broken
1144 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1146 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1148 <cpu number>,...,<cpu number>
1150 <cpu number>-<cpu number>
1151 (must be a positive range in ascending order)
1153 <cpu number>,...,<cpu number>-<cpu number>
1155 This option can be used to specify one or more CPUs
1156 to isolate from the general SMP balancing and scheduling
1157 algorithms. You can move a process onto or off an
1158 "isolated" CPU via the CPU affinity syscalls or cpuset.
1159 <cpu number> begins at 0 and the maximum value is
1160 "number of CPUs in system - 1".
1162 This option is the preferred way to isolate CPUs. The
1163 alternative -- manually setting the CPU mask of all
1164 tasks in the system -- can cause problems and
1165 suboptimal load balancer performance.
1169 js= [HW,JOY] Analog joystick
1170 See Documentation/input/joystick.txt.
1174 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1175 specifies the amount of memory usable by the kernel
1176 for non-movable allocations. The requested amount is
1177 spread evenly throughout all nodes in the system. The
1178 remaining memory in each node is used for Movable
1179 pages. In the event, a node is too small to have both
1180 kernelcore and Movable pages, kernelcore pages will
1181 take priority and other nodes will have a larger number
1182 of kernelcore pages. The Movable zone is used for the
1183 allocation of pages that may be reclaimed or moved
1184 by the page migration subsystem. This means that
1185 HugeTLB pages may not be allocated from this zone.
1186 Note that allocations like PTEs-from-HighMem still
1187 use the HighMem zone if it exists, and the Normal
1188 zone if it does not.
1190 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1191 Format: <Controller#>[,poll interval]
1192 The controller # is the number of the ehci usb debug
1193 port as it is probed via PCI. The poll interval is
1194 optional and is the number seconds in between
1195 each poll cycle to the debug port in case you need
1196 the functionality for interrupting the kernel with
1197 gdb or control-c on the dbgp connection. When
1198 not using this parameter you use sysrq-g to break into
1199 the kernel debugger.
1201 kgdboc= [KGDB,HW] kgdb over consoles.
1202 Requires a tty driver that supports console polling,
1203 or a supported polling keyboard driver (non-usb).
1204 Serial only format: <serial_device>[,baud]
1205 keyboard only format: kbd
1206 keyboard and serial format: kbd,<serial_device>[,baud]
1207 Optional Kernel mode setting:
1208 kms, kbd format: kms,kbd
1209 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1211 kgdbwait [KGDB] Stop kernel execution and enter the
1212 kernel debugger at the earliest opportunity.
1214 kmac= [MIPS] korina ethernet MAC address.
1215 Configure the RouterBoard 532 series on-chip
1216 Ethernet adapter MAC address.
1218 kmemleak= [KNL] Boot-time kmemleak enable/disable
1219 Valid arguments: on, off
1222 kstack=N [X86] Print N words from the kernel stack
1225 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1226 Default is 0 (don't ignore, but inject #GP)
1228 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1229 Default is 1 (enabled)
1231 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1235 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1236 Default is 1 (enabled)
1238 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1240 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1242 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1243 (virtualized MMU) support on capable Intel chips.
1244 Default is 1 (enabled)
1246 kvm-intel.emulate_invalid_guest_state=
1247 [KVM,Intel] Enable emulation of invalid guest states
1248 Default is 0 (disabled)
1250 kvm-intel.flexpriority=
1251 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1252 Default is 1 (enabled)
1255 [KVM,Intel] Enable VMX nesting (nVMX).
1256 Default is 0 (disabled)
1258 kvm-intel.unrestricted_guest=
1259 [KVM,Intel] Disable unrestricted guest feature
1260 (virtualized real and unpaged mode) on capable
1261 Intel chips. Default is 1 (enabled)
1263 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1264 feature (tagged TLBs) on capable Intel chips.
1265 Default is 1 (enabled)
1271 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1274 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1277 libata.dma= [LIBATA] DMA control
1278 libata.dma=0 Disable all PATA and SATA DMA
1279 libata.dma=1 PATA and SATA Disk DMA only
1280 libata.dma=2 ATAPI (CDROM) DMA only
1281 libata.dma=4 Compact Flash DMA only
1282 Combinations also work, so libata.dma=3 enables DMA
1283 for disks and CDROMs, but not CFs.
1285 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1286 libata.ignore_hpa=0 keep BIOS limits (default)
1287 libata.ignore_hpa=1 ignore limits, using full disk
1289 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1293 libata.force= [LIBATA] Force configurations. The format is comma
1294 separated list of "[ID:]VAL" where ID is
1295 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1296 matching port, link or device. Basically, it matches
1297 the ATA ID string printed on console by libata. If
1298 the whole ID part is omitted, the last PORT and DEVICE
1299 values are used. If ID hasn't been specified yet, the
1300 configuration applies to all ports, links and devices.
1302 If only DEVICE is omitted, the parameter applies to
1303 the port and all links and devices behind it. DEVICE
1304 number of 0 either selects the first device or the
1305 first fan-out link behind PMP device. It does not
1306 select the host link. DEVICE number of 15 selects the
1307 host link and device attached to it.
1309 The VAL specifies the configuration to force. As long
1310 as there's no ambiguity shortcut notation is allowed.
1311 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1312 The following configurations can be forced.
1314 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1315 Any ID with matching PORT is used.
1317 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1319 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1320 udma[/][16,25,33,44,66,100,133] notation is also
1323 * [no]ncq: Turn on or off NCQ.
1325 * nohrst, nosrst, norst: suppress hard, soft
1328 * dump_id: dump IDENTIFY data.
1330 If there are multiple matching configurations changing
1331 the same attribute, the last one is used.
1333 memblock=debug [KNL] Enable memblock debug messages.
1335 load_ramdisk= [RAM] List of ramdisks to load from floppy
1336 See Documentation/blockdev/ramdisk.txt.
1338 lockd.nlm_grace_period=P [NFS] Assign grace period.
1341 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1344 lockd.nlm_timeout=T [NFS] Assign timeout value.
1347 lockd.nlm_udpport=M [NFS] Assign UDP port.
1350 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1353 loglevel= All Kernel Messages with a loglevel smaller than the
1354 console loglevel will be printed to the console. It can
1355 also be changed with klogd or other programs. The
1356 loglevels are defined as follows:
1358 0 (KERN_EMERG) system is unusable
1359 1 (KERN_ALERT) action must be taken immediately
1360 2 (KERN_CRIT) critical conditions
1361 3 (KERN_ERR) error conditions
1362 4 (KERN_WARNING) warning conditions
1363 5 (KERN_NOTICE) normal but significant condition
1364 6 (KERN_INFO) informational
1365 7 (KERN_DEBUG) debug-level messages
1367 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1368 in bytes. n must be a power of two. The default
1369 size is set in the kernel config file.
1371 logo.nologo [FB] Disables display of the built-in Linux logo.
1372 This may be used to provide more screen space for
1373 kernel log messages and is useful when debugging
1374 kernel boot problems.
1376 lp=0 [LP] Specify parallel ports to use, e.g,
1377 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1378 lp=reset first parallel port). 'lp=0' disables the
1379 lp=auto printer driver. 'lp=reset' (which can be
1380 specified in addition to the ports) causes
1381 attached printers to be reset. Using
1382 lp=port1,port2,... specifies the parallel ports
1383 to associate lp devices with, starting with
1384 lp0. A port specification may be 'none' to skip
1385 that lp device, or a parport name such as
1386 'parport0'. Specifying 'lp=auto' instead of a
1387 port specification list means that device IDs
1388 from each port should be examined, to see if
1389 an IEEE 1284-compliant printer is attached; if
1390 so, the driver will manage that printer.
1391 See also header of drivers/char/lp.c.
1394 Sets loops_per_jiffy to given constant, thus avoiding
1395 time-consuming boot-time autodetection (up to 250 ms per
1396 CPU). 0 enables autodetection (default). To determine
1397 the correct value for your kernel, boot with normal
1398 autodetection and see what value is printed. Note that
1399 on SMP systems the preset will be applied to all CPUs,
1400 which is likely to cause problems if your CPUs need
1401 significantly divergent settings. An incorrect value
1402 will cause delays in the kernel to be wrong, leading to
1403 unpredictable I/O errors and other breakage. Although
1404 unlikely, in the extreme case this might damage your
1408 Format: <io>,<irq>,<dma>
1410 machvec= [IA-64] Force the use of a particular machine-vector
1411 (machvec) in a generic kernel.
1412 Example: machvec=hpzx1_swiotlb
1414 machtype= [Loongson] Share the same kernel image file between different
1416 Example: machtype=lemote-yeeloong-2f-7inch
1418 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1419 than or equal to this physical address is ignored.
1421 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1422 should make use of. maxcpus=n : n >= 0 limits the
1423 kernel to using 'n' processors. n=0 is a special case,
1424 it is equivalent to "nosmp", which also disables
1427 max_loop= [LOOP] The number of loop block devices that get
1428 (loop.max_loop) unconditionally pre-created at init time. The default
1429 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1430 of statically allocating a predefined number, loop
1431 devices can be requested on-demand with the
1432 /dev/loop-control interface.
1436 mce [X86-32] Machine Check Exception
1438 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1440 md= [HW] RAID subsystems devices and level
1441 See Documentation/md.txt.
1444 Format: <first>,<last>
1445 Specifies range of consoles to be captured by the MDA.
1447 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1448 Amount of memory to be used when the kernel is not able
1449 to see the whole system memory or for test.
1450 [X86-32] Use together with memmap= to avoid physical
1451 address space collisions. Without memmap= PCI devices
1452 could be placed at addresses belonging to unused RAM.
1454 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1458 [KNL,SH] Allow user to override the default size for
1459 per-device physically contiguous DMA buffers.
1461 memmap=exactmap [KNL,X86] Enable setting of an exact
1462 E820 memory map, as specified by the user.
1463 Such memmap=exactmap lines can be constructed based on
1464 BIOS output or other requirements. See the memmap=nn@ss
1467 memmap=nn[KMG]@ss[KMG]
1468 [KNL] Force usage of a specific region of memory
1469 Region of memory to be used, from ss to ss+nn.
1471 memmap=nn[KMG]#ss[KMG]
1472 [KNL,ACPI] Mark specific memory as ACPI data.
1473 Region of memory to be used, from ss to ss+nn.
1475 memmap=nn[KMG]$ss[KMG]
1476 [KNL,ACPI] Mark specific memory as reserved.
1477 Region of memory to be used, from ss to ss+nn.
1478 Example: Exclude memory from 0x18690000-0x1869ffff
1479 memmap=64K$0x18690000
1481 memmap=0x10000$0x18690000
1483 memory_corruption_check=0/1 [X86]
1484 Some BIOSes seem to corrupt the first 64k of
1485 memory when doing things like suspend/resume.
1486 Setting this option will scan the memory
1487 looking for corruption. Enabling this will
1488 both detect corruption and prevent the kernel
1489 from using the memory being corrupted.
1490 However, its intended as a diagnostic tool; if
1491 repeatable BIOS-originated corruption always
1492 affects the same memory, you can use memmap=
1493 to prevent the kernel from using that memory.
1495 memory_corruption_check_size=size [X86]
1496 By default it checks for corruption in the low
1497 64k, making this memory unavailable for normal
1498 use. Use this parameter to scan for
1499 corruption in more or less memory.
1501 memory_corruption_check_period=seconds [X86]
1502 By default it checks for corruption every 60
1503 seconds. Use this parameter to check at some
1504 other rate. 0 disables periodic checking.
1506 memtest= [KNL,X86] Enable memtest
1508 default : 0 <disable>
1509 Specifies the number of memtest passes to be
1510 performed. Each pass selects another test
1511 pattern from a given set of patterns. Memtest
1512 fills the memory with this pattern, validates
1513 memory contents and reserves bad memory
1514 regions that are detected.
1516 meye.*= [HW] Set MotionEye Camera parameters
1517 See Documentation/video4linux/meye.txt.
1519 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1520 Multi-Function General Purpose Timers on AMD Geode
1523 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1524 the BIOS has incorrectly applied a workaround. TinyBIOS
1525 version 0.98 is known to be affected, 0.99 fixes the
1526 problem by letting the user disable the workaround.
1530 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1531 physical address is ignored.
1533 mini2440= [ARM,HW,KNL]
1534 Format:[0..2][b][c][t]
1536 MINI2440 configuration specification:
1537 0 - The attached screen is the 3.5" TFT
1538 1 - The attached screen is the 7" TFT
1539 2 - The VGA Shield is attached (1024x768)
1540 Leaving out the screen size parameter will not load
1541 the TFT driver, and the framebuffer will be left
1543 b - Enable backlight. The TFT backlight pin will be
1544 linked to the kernel VESA blanking code and a GPIO
1545 LED. This parameter is not necessary when using the
1547 c - Enable the s3c camera interface.
1548 t - Reserved for enabling touchscreen support. The
1549 touchscreen support is not enabled in the mainstream
1550 kernel as of 2.6.30, a preliminary port can be found
1551 in the "bleeding edge" mini2440 support kernel at
1552 http://repo.or.cz/w/linux-2.6/mini2440.git
1555 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1556 parameter allows control of the logging verbosity for
1557 the additional memory initialisation checks. A value
1558 of 0 disables mminit logging and a level of 4 will
1559 log everything. Information is printed at KERN_DEBUG
1560 so loglevel=8 may also need to be specified.
1563 [MOUSE] Maximum time between finger touching and
1564 leaving touchpad surface for touch to be considered
1565 a tap and be reported as a left button click (for
1566 touchpads working in absolute mode only).
1568 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1569 reporting absolute coordinates, such as tablets
1570 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1571 reporting absolute coordinates, such as tablets
1573 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1574 is similar to kernelcore except it specifies the
1575 amount of memory used for migratable allocations.
1576 If both kernelcore and movablecore is specified,
1577 then kernelcore will be at *least* the specified
1578 value but may be more. If movablecore on its own
1579 is specified, the administrator must be careful
1580 that the amount of memory usable for all allocations
1583 MTD_Partition= [MTD]
1584 Format: <name>,<region-number>,<size>,<offset>
1586 MTD_Region= [MTD] Format:
1587 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1590 See drivers/mtd/cmdlinepart.c.
1592 multitce=off [PPC] This parameter disables the use of the pSeries
1593 firmware feature for updating multiple TCE entries
1596 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1598 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1600 boundary - index of last SLC block on Flex-OneNAND.
1601 The remaining blocks are configured as MLC blocks.
1602 lock - Configure if Flex-OneNAND boundary should be locked.
1603 Once locked, the boundary cannot be changed.
1604 1 indicates lock status, 0 indicates unlock status.
1607 ARM/S3C2412 JIVE boot control
1609 See arch/arm/mach-s3c2412/mach-jive.c
1611 mtouchusb.raw_coordinates=
1612 [HW] Make the MicroTouch USB driver use raw coordinates
1613 ('y', default) or cooked coordinates ('n')
1615 mtrr_chunk_size=nn[KMG] [X86]
1616 used for mtrr cleanup. It is largest continuous chunk
1617 that could hold holes aka. UC entries.
1619 mtrr_gran_size=nn[KMG] [X86]
1620 Used for mtrr cleanup. It is granularity of mtrr block.
1622 Large value could prevent small alignment from
1625 mtrr_spare_reg_nr=n [X86]
1627 Range: 0,7 : spare reg number
1629 Used for mtrr cleanup. It is spare mtrr entries number.
1630 Set to 2 or more if your graphical card needs more.
1632 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1634 netdev= [NET] Network devices parameters
1635 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1636 Note that mem_start is often overloaded to mean
1637 something different and driver-specific.
1638 This usage is only documented in each driver source
1642 [NETFILTER] Enable connection tracking flow accounting
1643 0 to disable accounting
1644 1 to enable accounting
1647 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1648 See Documentation/filesystems/nfs/nfsroot.txt.
1650 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1651 See Documentation/filesystems/nfs/nfsroot.txt.
1653 nfsrootdebug [NFS] enable nfsroot debugging messages.
1654 See Documentation/filesystems/nfs/nfsroot.txt.
1656 nfs.callback_tcpport=
1657 [NFS] set the TCP port on which the NFSv4 callback
1658 channel should listen.
1661 [NFS] sets the pathname to the program which is used
1662 to update the NFS client cache entries.
1664 nfs.cache_getent_timeout=
1665 [NFS] sets the timeout after which an attempt to
1666 update a cache entry is deemed to have failed.
1668 nfs.idmap_cache_timeout=
1669 [NFS] set the maximum lifetime for idmapper cache
1673 [NFS] enable 64-bit inode numbers.
1674 If zero, the NFS client will fake up a 32-bit inode
1675 number for the readdir() and stat() syscalls instead
1676 of returning the full 64-bit number.
1677 The default is to return 64-bit inode numbers.
1679 nfs.nfs4_disable_idmapping=
1680 [NFSv4] When set, this option disables the NFSv4
1681 idmapper on the client, but only if the mount
1682 is using the 'sec=sys' security flavour. This may
1683 make migration from legacy NFSv2/v3 systems easier
1684 provided that the server has the appropriate support.
1685 The default is to always enable NFSv4 idmapping.
1687 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1688 when a NMI is triggered.
1689 Format: [state][,regs][,debounce][,die]
1691 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1692 Format: [panic,][nopanic,][num]
1694 0 - turn nmi_watchdog off
1695 When panic is specified, panic when an NMI watchdog
1696 timeout occurs (or 'nopanic' to override the opposite
1698 This is useful when you use a panic=... timeout and
1699 need the box quickly up again.
1701 netpoll.carrier_timeout=
1702 [NET] Specifies amount of time (in seconds) that
1703 netpoll should wait for a carrier. By default netpoll
1706 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1707 emulation library even if a 387 maths coprocessor
1711 [HW] Never suspend the console
1712 Disable suspending of consoles during suspend and
1713 hibernate operations. Once disabled, debugging
1714 messages can reach various consoles while the rest
1715 of the system is being put to sleep (ie, while
1716 debugging driver suspend/resume hooks). This may
1717 not work reliably with all consoles, but is known
1718 to work with serial and VGA consoles.
1719 To facilitate more flexible debugging, we also add
1720 console_suspend, a printk module parameter to control
1721 it. Users could use console_suspend (usually
1722 /sys/module/printk/parameters/console_suspend) to
1723 turn on/off it dynamically.
1725 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1726 caches in the slab allocator. Saves per-node memory,
1727 but will impact performance.
1731 noapic [SMP,APIC] Tells the kernel to not make use of any
1732 IOAPICs that may be present in the system.
1734 noautogroup Disable scheduler automatic task group creation.
1736 nobats [PPC] Do not use BATs for mapping kernel lowmem
1737 on "Classic" PPC cores.
1741 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1743 nodelayacct [KNL] Disable per-task delay accounting
1745 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1747 nodsp [SH] Disable hardware DSP at boot time.
1749 noefi [X86] Disable EFI runtime services support.
1754 On X86-32 available only on PAE configured kernels.
1755 noexec=on: enable non-executable mappings (default)
1756 noexec=off: disable non-executable mappings
1759 Disable SMEP (Supervisor Mode Execution Protection)
1760 even if it is supported by processor.
1763 This affects only 32-bit executables.
1764 noexec32=on: enable non-executable mappings (default)
1765 read doesn't imply executable mappings
1766 noexec32=off: disable non-executable mappings
1767 read implies executable mappings
1769 nofpu [SH] Disable hardware FPU at boot time.
1771 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1772 register save and restore. The kernel will only save
1773 legacy floating-point registers on task switch.
1775 noxsave [BUGS=X86] Disables x86 extended register state save
1776 and restore using xsave. The kernel will fallback to
1777 enabling legacy floating-point and sse state.
1779 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1780 wfi(ARM) instruction doesn't work correctly and not to
1781 use it. This is also useful when using JTAG debugger.
1783 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1784 instruction doesn't work correctly and not to
1787 no_file_caps Tells the kernel not to honor file capabilities. The
1788 only way then for a file to be executed with privilege
1789 is to be setuid root or executed by root.
1791 nohalt [IA-64] Tells the kernel not to use the power saving
1792 function PAL_HALT_LIGHT when idle. This increases
1793 power-consumption. On the positive side, it reduces
1794 interrupt wake-up latency, which may improve performance
1795 in certain environments such as networked servers or
1798 nohz= [KNL] Boottime enable/disable dynamic ticks
1799 Valid arguments: on, off
1802 noiotrap [SH] Disables trapped I/O port accesses.
1804 noirqdebug [X86-32] Disables the code which attempts to detect and
1805 disable unhandled interrupt sources.
1807 no_timer_check [X86,APIC] Disables the code which tests for
1808 broken timer IRQ sources.
1810 noisapnp [ISAPNP] Disables ISA PnP code.
1812 noinitrd [RAM] Tells the kernel not to load any configured
1815 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1817 [Deprecated - use intremap=off]
1821 nojitter [IA-64] Disables jitter checking for ITC timers.
1823 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1825 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1828 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1829 steal time is computed, but won't influence scheduler
1832 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1834 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1836 noltlbs [PPC] Do not use large page/tlb entries for kernel
1837 lowmem mapping on PPC40x.
1839 nomca [IA-64] Disable machine check abort handling
1841 nomce [X86-32] Machine Check Exception
1843 nomfgpt [X86-32] Disable Multi-Function General Purpose
1844 Timer usage (for AMD Geode machines).
1846 nopat [X86] Disable PAT (page attribute table extension of
1847 pagetables) support.
1849 norandmaps Don't use address space randomization. Equivalent to
1850 echo 0 > /proc/sys/kernel/randomize_va_space
1852 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1854 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1855 with UP alternatives
1857 noresidual [PPC] Don't use residual data on PReP machines.
1859 nordrand [X86] Disable the direct use of the RDRAND
1860 instruction even if it is supported by the
1861 processor. RDRAND is still available to user
1864 noresume [SWSUSP] Disables resume and restores original swap
1867 no-scroll [VGA] Disables scrollback.
1868 This is required for the Braillex ib80-piezo Braille
1869 reader made by F.H. Papenmeier (Germany).
1873 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1875 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1876 and disable the IO APIC. legacy for "maxcpus=0".
1878 nosoftlockup [KNL] Disable the soft-lockup detector.
1880 nosync [HW,M68K] Disables sync negotiation for all devices.
1882 notsc [BUGS=X86-32] Disable Time Stamp Counter
1884 nousb [USB] Disable the USB subsystem
1886 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1890 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1892 nptcg= [IA-64] Override max number of concurrent global TLB
1893 purges which is reported from either PAL_VM_SUMMARY or
1896 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1897 could support. nr_cpus=n : n >= 1 limits the kernel to
1898 supporting 'n' processors. Later in runtime you can not
1899 use hotplug cpu feature to put more cpu back to online.
1900 just like you compile the kernel NR_CPUS=n
1902 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1904 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1905 one of ['zone', 'node', 'default'] can be specified
1906 This can be set from sysctl after boot.
1907 See Documentation/sysctl/vm.txt for details.
1909 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1910 See Documentation/debugging-via-ohci1394.txt for more
1913 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1914 Rather than timing out after 20 ms if an EC
1915 command is not properly ACKed, override the length
1916 of the timeout. We have interrupts disabled while
1917 waiting for the ACK, so if this is set too high
1918 interrupts *may* be lost!
1920 omap_mux= [OMAP] Override bootloader pin multiplexing.
1921 Format: <mux_mode0.mode_name=value>...
1922 For example, to override I2C bus2:
1923 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1925 oprofile.timer= [HW]
1926 Use timer interrupt instead of performance counters
1928 oprofile.cpu_type= Force an oprofile cpu type
1929 This might be useful if you have an older oprofile
1930 userland or if you want common events.
1931 Format: { arch_perfmon }
1932 arch_perfmon: [X86] Force use of architectural
1933 perfmon on Intel CPUs instead of the
1934 CPU specific event set.
1936 oops=panic Always panic on oopses. Default is to just kill the
1937 process, but there is a small probability of
1938 deadlocking the machine.
1939 This will also cause panics on machine check exceptions.
1940 Useful together with panic=30 to trigger a reboot.
1943 See Documentation/sound/oss/oss-parameters.txt
1945 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1946 timeout > 0: seconds before rebooting
1947 timeout = 0: wait forever
1948 timeout < 0: reboot immediately
1951 parkbd.port= [HW] Parallel port number the keyboard adapter is
1952 connected to, default is 0.
1954 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1955 0 for XT, 1 for AT (default is AT).
1958 parport= [HW,PPT] Specify parallel ports. 0 disables.
1959 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1960 Use 'auto' to force the driver to use any
1961 IRQ/DMA settings detected (the default is to
1962 ignore detected IRQ/DMA settings because of
1963 possible conflicts). You can specify the base
1964 address, IRQ, and DMA settings; IRQ and DMA
1965 should be numbers, or 'auto' (for using detected
1966 settings on that particular port), or 'nofifo'
1967 (to avoid using a FIFO even if it is detected).
1968 Parallel ports are assigned in the order they
1969 are specified on the command line, starting
1972 parport_init_mode= [HW,PPT]
1973 Configure VIA parallel port to operate in
1974 a specific mode. This is necessary on Pegasos
1975 computer where firmware has no options for setting
1976 up parallel port mode and sets it to spp.
1977 Currently this function knows 686a and 8231 chips.
1978 Format: [spp|ps2|epp|ecp|ecpepp]
1981 Halt all CPUs after the first oops has been printed for
1982 the specified number of seconds. This is to be used if
1983 your oopses keep scrolling off the screen.
1988 See header of drivers/block/paride/pcd.c.
1989 See also Documentation/blockdev/paride.txt.
1991 pci=option[,option...] [PCI] various PCI subsystem options:
1992 earlydump [X86] dump PCI config space before the kernel
1994 off [X86] don't probe for the PCI bus
1995 bios [X86-32] force use of PCI BIOS, don't access
1996 the hardware directly. Use this if your machine
1997 has a non-standard PCI host bridge.
1998 nobios [X86-32] disallow use of PCI BIOS, only direct
1999 hardware access methods are allowed. Use this
2000 if you experience crashes upon bootup and you
2001 suspect they are caused by the BIOS.
2002 conf1 [X86] Force use of PCI Configuration
2004 conf2 [X86] Force use of PCI Configuration
2006 noaer [PCIE] If the PCIEAER kernel config parameter is
2007 enabled, this kernel boot option can be used to
2008 disable the use of PCIE advanced error reporting.
2009 nodomains [PCI] Disable support for multiple PCI
2010 root domains (aka PCI segments, in ACPI-speak).
2011 nommconf [X86] Disable use of MMCONFIG for PCI
2013 check_enable_amd_mmconf [X86] check for and enable
2014 properly configured MMIO access to PCI
2015 config space on AMD family 10h CPU
2016 nomsi [MSI] If the PCI_MSI kernel config parameter is
2017 enabled, this kernel boot option can be used to
2018 disable the use of MSI interrupts system-wide.
2019 noioapicquirk [APIC] Disable all boot interrupt quirks.
2020 Safety option to keep boot IRQs enabled. This
2021 should never be necessary.
2022 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2023 primary IO-APIC for bridges that cannot disable
2024 boot IRQs. This fixes a source of spurious IRQs
2025 when the system masks IRQs.
2026 noioapicreroute [APIC] Disable workaround that uses the
2027 boot IRQ equivalent of an IRQ that connects to
2028 a chipset where boot IRQs cannot be disabled.
2029 The opposite of ioapicreroute.
2030 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2031 routing table. These calls are known to be buggy
2032 on several machines and they hang the machine
2033 when used, but on other computers it's the only
2034 way to get the interrupt routing table. Try
2035 this option if the kernel is unable to allocate
2036 IRQs or discover secondary PCI buses on your
2038 rom [X86] Assign address space to expansion ROMs.
2039 Use with caution as certain devices share
2040 address decoders between ROMs and other
2042 norom [X86] Do not assign address space to
2043 expansion ROMs that do not already have
2044 BIOS assigned address ranges.
2045 nobar [X86] Do not assign address space to the
2046 BARs that weren't assigned by the BIOS.
2047 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2048 assigned automatically to PCI devices. You can
2049 make the kernel exclude IRQs of your ISA cards
2051 pirqaddr=0xAAAAA [X86] Specify the physical address
2052 of the PIRQ table (normally generated
2053 by the BIOS) if it is outside the
2054 F0000h-100000h range.
2055 lastbus=N [X86] Scan all buses thru bus #N. Can be
2056 useful if the kernel is unable to find your
2057 secondary buses and you want to tell it
2058 explicitly which ones they are.
2059 assign-busses [X86] Always assign all PCI bus
2060 numbers ourselves, overriding
2061 whatever the firmware may have done.
2062 usepirqmask [X86] Honor the possible IRQ mask stored
2063 in the BIOS $PIR table. This is needed on
2064 some systems with broken BIOSes, notably
2065 some HP Pavilion N5400 and Omnibook XE3
2066 notebooks. This will have no effect if ACPI
2067 IRQ routing is enabled.
2068 noacpi [X86] Do not use ACPI for IRQ routing
2069 or for PCI scanning.
2070 use_crs [X86] Use PCI host bridge window information
2071 from ACPI. On BIOSes from 2008 or later, this
2072 is enabled by default. If you need to use this,
2073 please report a bug.
2074 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2075 If you need to use this, please report a bug.
2076 routeirq Do IRQ routing for all PCI devices.
2077 This is normally done in pci_enable_device(),
2078 so this option is a temporary workaround
2079 for broken drivers that don't call it.
2080 skip_isa_align [X86] do not align io start addr, so can
2081 handle more pci cards
2082 firmware [ARM] Do not re-enumerate the bus but instead
2083 just use the configuration from the
2084 bootloader. This is currently used on
2085 IXP2000 systems where the bus has to be
2086 configured a certain way for adjunct CPUs.
2087 noearly [X86] Don't do any early type 1 scanning.
2088 This might help on some broken boards which
2089 machine check when some devices' config space
2090 is read. But various workarounds are disabled
2091 and some IOMMU drivers will not work.
2092 bfsort Sort PCI devices into breadth-first order.
2093 This sorting is done to get a device
2094 order compatible with older (<= 2.4) kernels.
2095 nobfsort Don't sort PCI devices into breadth-first order.
2096 cbiosize=nn[KMG] The fixed amount of bus space which is
2097 reserved for the CardBus bridge's IO window.
2098 The default value is 256 bytes.
2099 cbmemsize=nn[KMG] The fixed amount of bus space which is
2100 reserved for the CardBus bridge's memory
2101 window. The default value is 64 megabytes.
2104 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2105 Specifies alignment and device to reassign
2106 aligned memory resources.
2107 If <order of align> is not specified,
2108 PAGE_SIZE is used as alignment.
2109 PCI-PCI bridge can be specified, if resource
2110 windows need to be expanded.
2111 ecrc= Enable/disable PCIe ECRC (transaction layer
2112 end-to-end CRC checking).
2113 bios: Use BIOS/firmware settings. This is the
2117 realloc reallocate PCI resources if allocations done by BIOS
2120 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2123 force Enable ASPM even on devices that claim not to support it.
2124 WARNING: Forcing ASPM on may cause system lockups.
2126 pcie_ports= [PCIE] PCIe ports handling:
2127 auto Ask the BIOS whether or not to use native PCIe services
2128 associated with PCIe ports (PME, hot-plug, AER). Use
2129 them only if that is allowed by the BIOS.
2130 native Use native PCIe services associated with PCIe ports
2132 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2135 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2136 nomsi Do not use MSI for native PCIe PME signaling (this makes
2137 all PCIe root ports use INTx for all services).
2139 pcmv= [HW,PCMCIA] BadgePAD 4
2142 See Documentation/blockdev/paride.txt.
2144 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2147 See arch/parisc/kernel/pdc_chassis.c
2149 percpu_alloc= Select which percpu first chunk allocator to use.
2150 Currently supported values are "embed" and "page".
2151 Archs may support subset or none of the selections.
2152 See comments in mm/percpu.c for details on each
2153 allocator. This parameter is primarily for debugging
2154 and performance comparison.
2157 See Documentation/blockdev/paride.txt.
2160 See Documentation/blockdev/paride.txt.
2162 pirq= [SMP,APIC] Manual mp-table setup
2163 See Documentation/x86/i386/IO-APIC.txt.
2165 plip= [PPT,NET] Parallel port network link
2166 Format: { parport<nr> | timid | 0 }
2167 See also Documentation/parport.txt.
2169 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2170 Override pmtimer IOPort with a hex value.
2174 Enable PNP debug messages (depends on the
2175 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2176 via /sys/module/pnp/parameters/debug. We always show
2177 current resource usage; turning this on also shows
2178 possible settings and some assignment information.
2184 { on | off | curr | res | no-curr | no-res }
2187 [ISAPNP] Exclude IRQs for the autoconfiguration
2190 [ISAPNP] Exclude DMAs for the autoconfiguration
2192 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2193 Ranges are in pairs (I/O port base and size).
2196 [ISAPNP] Exclude memory regions for the
2198 Ranges are in pairs (memory base and size).
2200 ports= [IP_VS_FTP] IPVS ftp helper module
2202 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2204 Format: <port>,<port>....
2206 print-fatal-signals=
2207 [KNL] debug: print fatal signals
2209 If enabled, warn about various signal handling
2210 related application anomalies: too many signals,
2211 too many POSIX.1 timers, fatal signals causing a
2214 If you hit the warning due to signal overflow,
2215 you might want to try "ulimit -i unlimited".
2219 printk.time= Show timing data prefixed to each printk message line
2220 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2222 processor.max_cstate= [HW,ACPI]
2223 Limit processor to maximum C-state
2224 max_cstate=9 overrides any DMI blacklist limit.
2226 processor.nocst [HW,ACPI]
2227 Ignore the _CST method to determine C-states,
2228 instead using the legacy FADT method
2230 profile= [KNL] Enable kernel profiling via /proc/profile
2231 Format: [schedule,]<number>
2232 Param: "schedule" - profile schedule points.
2233 Param: <number> - step/bucket size as a power of 2 for
2234 statistical time based profiling.
2235 Param: "sleep" - profile D-state sleeping (millisecs).
2236 Requires CONFIG_SCHEDSTATS
2237 Param: "kvm" - profile VM exits.
2239 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2241 See Documentation/blockdev/ramdisk.txt.
2243 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2244 probe for; one of (bare|imps|exps|lifebook|any).
2245 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2247 psmouse.resetafter= [HW,MOUSE]
2248 Try to reset the device after so many bad packets
2251 [HW,MOUSE] Set desired mouse resolution, in dpi.
2252 psmouse.smartscroll=
2253 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2254 0 = disabled, 1 = enabled (default).
2256 pstore.backend= Specify the name of the pstore backend to use
2259 See Documentation/blockdev/paride.txt.
2262 [KNL] Number of legacy pty's. Overwrites compiled-in
2265 quiet [KNL] Disable most log messages
2270 See Documentation/md.txt.
2272 ramdisk_blocksize= [RAM]
2273 See Documentation/blockdev/ramdisk.txt.
2275 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2276 See Documentation/blockdev/ramdisk.txt.
2278 rcupdate.blimit= [KNL,BOOT]
2279 Set maximum number of finished RCU callbacks to process
2282 rcupdate.qhimark= [KNL,BOOT]
2283 Set threshold of queued
2284 RCU callbacks over which batch limiting is disabled.
2286 rcupdate.qlowmark= [KNL,BOOT]
2287 Set threshold of queued RCU callbacks below which
2288 batch limiting is re-enabled.
2292 Run specified binary instead of /init from the ramdisk,
2293 used for early userspace startup. See initrd.
2295 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2296 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2297 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2300 [KNL, SMP] Set scheduler's default relax_domain_level.
2301 See Documentation/cgroups/cpusets.txt.
2303 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2305 reservetop= [X86-32]
2307 Reserves a hole at the top of the kernel virtual
2312 Set the amount of memory to reserve for BIOS at
2313 the bottom of the address space.
2315 reset_devices [KNL] Force drivers to reset the underlying device
2316 during initialization.
2319 Specify the partition device for software suspend
2321 resume_offset= [SWSUSP]
2322 Specify the offset from the beginning of the partition
2323 given by "resume=" at which the swap header is located,
2324 in <PAGE_SIZE> units (needed only for swap files).
2325 See Documentation/power/swsusp-and-swap-files.txt
2327 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2328 read the resume files
2330 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2331 Useful for devices that are detected asynchronously
2332 (e.g. USB and MMC devices).
2334 hibernate= [HIBERNATION]
2335 noresume Don't check if there's a hibernation image
2336 present during boot.
2337 nocompress Don't compress/decompress hibernation images.
2339 retain_initrd [RAM] Keep initrd memory after extraction
2341 rhash_entries= [KNL,NET]
2342 Set number of hash buckets for route cache
2344 riscom8= [HW,SERIAL]
2345 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2347 ro [KNL] Mount root device read-only on boot
2349 root= [KNL] Root filesystem
2350 See name_to_dev_t comment in init/do_mounts.c.
2352 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2353 mount the root filesystem
2355 rootflags= [KNL] Set root filesystem mount option string
2357 rootfstype= [KNL] Set root filesystem type
2359 rootwait [KNL] Wait (indefinitely) for root device to show up.
2360 Useful for devices that are detected asynchronously
2361 (e.g. USB and MMC devices).
2363 rw [KNL] Mount root device read-write on boot
2365 S [KNL] Run init in single mode
2368 See drivers/net/irda/sa1100_ir.c.
2370 sbni= [NET] Granch SBNI12 leased line adapter
2372 sched_debug [KNL] Enables verbose scheduler debug messages.
2374 security= [SECURITY] Choose a security module to enable at boot.
2375 If this boot parameter is not specified, only the first
2376 security module asking for security registration will be
2377 loaded. An invalid security module name will be treated
2378 as if no module has been chosen.
2380 selinux= [SELINUX] Disable or enable SELinux at boot time.
2381 Format: { "0" | "1" }
2382 See security/selinux/Kconfig help text.
2385 Default value is set via kernel config option.
2386 If enabled at boot time, /selinux/disable can be used
2387 later to disable prior to initial policy load.
2389 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2390 Format: { "0" | "1" }
2391 See security/apparmor/Kconfig help text
2394 Default value is set via kernel config option.
2396 serialnumber [BUGS=X86-32]
2399 Maximal number of shapers.
2401 show_msr= [x86] show boot-time MSR settings
2402 Format: { <integer> }
2403 Show boot-time (BIOS-initialized) MSR settings.
2404 The parameter means the number of CPUs to show,
2405 for example 1 means boot CPU only.
2412 slub_debug[=options[,slabs]] [MM, SLUB]
2413 Enabling slub_debug allows one to determine the
2414 culprit if slab objects become corrupted. Enabling
2415 slub_debug can create guard zones around objects and
2416 may poison objects when not in use. Also tracks the
2417 last alloc / free. For more information see
2418 Documentation/vm/slub.txt.
2420 slub_max_order= [MM, SLUB]
2421 Determines the maximum allowed order for slabs.
2422 A high setting may cause OOMs due to memory
2423 fragmentation. For more information see
2424 Documentation/vm/slub.txt.
2426 slub_min_objects= [MM, SLUB]
2427 The minimum number of objects per slab. SLUB will
2428 increase the slab order up to slub_max_order to
2429 generate a sufficiently large slab able to contain
2430 the number of objects indicated. The higher the number
2431 of objects the smaller the overhead of tracking slabs
2432 and the less frequently locks need to be acquired.
2433 For more information see Documentation/vm/slub.txt.
2435 slub_min_order= [MM, SLUB]
2436 Determines the mininum page order for slabs. Must be
2437 lower than slub_max_order.
2438 For more information see Documentation/vm/slub.txt.
2440 slub_nomerge [MM, SLUB]
2441 Disable merging of slabs with similar size. May be
2442 necessary if there is some reason to distinguish
2443 allocs to different slabs. Debug options disable
2444 merging on their own.
2445 For more information see Documentation/vm/slub.txt.
2448 Format: <io1>[,<io2>[,...,<io8>]]
2450 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2451 attempt to substitute SMP alternatives once at boot.
2453 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2454 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2455 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2456 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2457 smsc-ircc2.ircc_irq= [HW] IRQ line
2458 smsc-ircc2.ircc_dma= [HW] DMA channel
2459 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2460 0: Toshiba Satellite 1800 (GP data pin select)
2461 1: Fast pin select (default)
2465 [KNL] Should the soft-lockup detector generate panics.
2468 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2469 See Documentation/laptops/sonypi.txt
2471 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2472 See Documentation/serial/specialix.txt.
2474 spia_io_base= [HW,MTD]
2480 Enabled the stack tracer on boot up.
2484 Set the STI (builtin display/keyboard on the HP-PARISC
2485 machines) console (graphic card) which should be used
2486 as the initial boot-console.
2487 See also comment in drivers/video/console/sticore.c.
2490 See comment in drivers/video/console/sticore.c.
2493 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2495 sunrpc.min_resvport=
2496 sunrpc.max_resvport=
2498 SunRPC servers often require that client requests
2499 originate from a privileged port (i.e. a port in the
2500 range 0 < portnr < 1024).
2501 An administrator who wishes to reserve some of these
2502 ports for other uses may adjust the range that the
2503 kernel's sunrpc client considers to be privileged
2504 using these two parameters to set the minimum and
2505 maximum port values.
2509 Control how the NFS server code allocates CPUs to
2510 service thread pools. Depending on how many NICs
2511 you have and where their interrupts are bound, this
2512 option will affect which CPUs will do NFS serving.
2513 Note: this parameter cannot be changed while the
2514 NFS server is running.
2516 auto the server chooses an appropriate mode
2517 automatically using heuristics
2518 global a single global pool contains all CPUs
2519 percpu one pool for each CPU
2520 pernode one pool for each NUMA node (equivalent
2521 to global on non-NUMA machines)
2523 sunrpc.tcp_slot_table_entries=
2524 sunrpc.udp_slot_table_entries=
2526 Sets the upper limit on the number of simultaneous
2527 RPC calls that can be sent from the client to a
2528 server. Increasing these values may allow you to
2529 improve throughput, but will also increase the
2530 amount of memory reserved for use by the client.
2533 [KNL] Enable accounting of swap in memory resource
2534 controller if no parameter or 1 is given or disable
2535 it if 0 is given (See Documentation/cgroups/memory.txt)
2537 swiotlb= [IA-64] Number of I/O TLB slabs
2541 sysfs.deprecated=0|1 [KNL]
2542 Enable/disable old style sysfs layout for old udev
2543 on older distributions. When this option is enabled
2544 very new udev will not work anymore. When this option
2545 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2546 in older udev will not work anymore.
2547 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2548 the kernel configuration.
2550 sysrq_always_enabled
2552 Ignore sysrq setting - this boot parameter will
2553 neutralize any effect of /proc/sys/kernel/sysrq.
2554 Useful for debugging.
2558 test_suspend= [SUSPEND]
2559 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2560 standby suspend) as the system sleep state to briefly
2561 enter during system startup. The system is woken from
2562 this state using a wakeup-capable RTC alarm.
2564 thash_entries= [KNL,NET]
2565 Set number of hash buckets for TCP connection
2567 thermal.act= [HW,ACPI]
2568 -1: disable all active trip points in all thermal zones
2569 <degrees C>: override all lowest active trip points
2571 thermal.crt= [HW,ACPI]
2572 -1: disable all critical trip points in all thermal zones
2573 <degrees C>: override all critical trip points
2575 thermal.nocrt= [HW,ACPI]
2576 Set to disable actions on ACPI thermal zone
2577 critical and hot trip points.
2579 thermal.off= [HW,ACPI]
2580 1: disable ACPI thermal control
2582 thermal.psv= [HW,ACPI]
2583 -1: disable all passive trip points
2584 <degrees C>: override all passive trip points to this
2587 thermal.tzp= [HW,ACPI]
2588 Specify global default ACPI thermal zone polling rate
2589 <deci-seconds>: poll all this frequency
2590 0: no polling (default)
2593 Force threading of all interrupt handlers except those
2594 marked explicitely IRQF_NO_THREAD.
2598 Specify if the kernel should make use of the cpu
2599 topology information if the hardware supports this.
2600 The scheduler will make use of this information and
2601 e.g. base its process migration decisions on it.
2606 tpm_suspend_pcr=[HW,TPM]
2607 Format: integer pcr id
2608 Specify that at suspend time, the tpm driver
2609 should extend the specified pcr with zeros,
2610 as a workaround for some chips which fail to
2611 flush the last written pcr on TPM_SaveState.
2612 This will guarantee that all the other pcrs
2615 trace_buf_size=nn[KMG]
2616 [FTRACE] will set tracing buffer size.
2618 trace_event=[event-list]
2619 [FTRACE] Set and start specified trace events in order
2620 to facilitate early boot debugging.
2621 See also Documentation/trace/events.txt
2623 tsc= Disable clocksource stability checks for TSC.
2625 [x86] reliable: mark tsc clocksource as reliable, this
2626 disables clocksource verification at runtime, as well
2627 as the stability checks done at bootup. Used to enable
2628 high-resolution timer mode on older hardware, and in
2629 virtualized environment.
2630 [x86] noirqtime: Do not use TSC to do irq accounting.
2631 Used to run time disable IRQ_TIME_ACCOUNTING on any
2632 platforms where RDTSC is slow and this accounting
2635 turbografx.map[2|3]= [HW,JOY]
2636 TurboGraFX parallel port interface
2638 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2639 See also Documentation/input/joystick-parport.txt
2641 udbg-immortal [PPC] When debugging early kernel crashes that
2642 happen after console_init() and before a proper
2643 console driver takes over, this boot options might
2644 help "seeing" what's going on.
2646 uhash_entries= [KNL,NET]
2647 Set number of hash buckets for UDP/UDP-Lite connections
2650 [USB] Ignore overcurrent events (default N).
2651 Some badly-designed motherboards generate lots of
2652 bogus events, for ports that aren't wired to
2653 anything. Set this parameter to avoid log spamming.
2654 Note that genuine overcurrent events won't be
2658 [X86] Cause panic on unknown NMI.
2660 usbcore.authorized_default=
2661 [USB] Default USB device authorization:
2662 (default -1 = authorized except for wireless USB,
2663 0 = not authorized, 1 = authorized)
2665 usbcore.autosuspend=
2666 [USB] The autosuspend time delay (in seconds) used
2667 for newly-detected USB devices (default 2). This
2668 is the time required before an idle device will be
2669 autosuspended. Devices for which the delay is set
2670 to a negative value won't be autosuspended at all.
2672 usbcore.usbfs_snoop=
2673 [USB] Set to log all usbfs traffic (default 0 = off).
2675 usbcore.blinkenlights=
2676 [USB] Set to cycle leds on hubs (default 0 = off).
2678 usbcore.old_scheme_first=
2679 [USB] Start with the old device initialization
2680 scheme (default 0 = off).
2682 usbcore.use_both_schemes=
2683 [USB] Try the other device initialization scheme
2684 if the first one fails (default 1 = enabled).
2686 usbcore.initial_descriptor_timeout=
2687 [USB] Specifies timeout for the initial 64-byte
2688 USB_REQ_GET_DESCRIPTOR request in milliseconds
2689 (default 5000 = 5.0 seconds).
2692 [USBHID] The interval which mice are to be polled at.
2694 usb-storage.delay_use=
2695 [UMS] The delay in seconds before a new device is
2696 scanned for Logical Units (default 5).
2699 [UMS] A list of quirks entries to supplement or
2700 override the built-in unusual_devs list. List
2701 entries are separated by commas. Each entry has
2702 the form VID:PID:Flags where VID and PID are Vendor
2703 and Product ID values (4-digit hex numbers) and
2704 Flags is a set of characters, each corresponding
2705 to a common usb-storage quirk flag as follows:
2706 a = SANE_SENSE (collect more than 18 bytes
2708 b = BAD_SENSE (don't collect more than 18
2709 bytes of sense data);
2710 c = FIX_CAPACITY (decrease the reported
2711 device capacity by one sector);
2712 d = NO_READ_DISC_INFO (don't use
2713 READ_DISC_INFO command);
2714 e = NO_READ_CAPACITY_16 (don't use
2715 READ_CAPACITY_16 command);
2716 h = CAPACITY_HEURISTICS (decrease the
2717 reported device capacity by one
2718 sector if the number is odd);
2719 i = IGNORE_DEVICE (don't bind to this
2721 l = NOT_LOCKABLE (don't try to lock and
2722 unlock ejectable media);
2723 m = MAX_SECTORS_64 (don't transfer more
2724 than 64 sectors = 32 KB at a time);
2725 n = INITIAL_READ10 (force a retry of the
2726 initial READ(10) command);
2727 o = CAPACITY_OK (accept the capacity
2728 reported by the device);
2729 r = IGNORE_RESIDUE (the device reports
2730 bogus residue values);
2731 s = SINGLE_LUN (the device has only one
2733 w = NO_WP_DETECT (don't test whether the
2734 medium is write-protected).
2735 Example: quirks=0419:aaf5:rl,0421:0433:rc
2737 user_debug= [KNL,ARM]
2739 See arch/arm/Kconfig.debug help text.
2740 1 - undefined instruction events
2742 4 - invalid data aborts
2745 Example: user_debug=31
2748 [X86] Flags controlling user PTE allocations.
2750 nohigh = do not allocate PTE pages in
2751 HIGHMEM regardless of setting
2755 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2756 vdso=1: enable VDSO (default)
2757 vdso=0: disable VDSO mapping
2760 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2761 vdso32=1: enable 32-bit VDSO (default)
2762 vdso32=0: disable 32-bit VDSO mapping
2765 vector=percpu: enable percpu vector domain
2767 video= [FB] Frame buffer configuration
2768 See Documentation/fb/modedb.txt.
2770 vga= [BOOT,X86-32] Select a particular video mode
2771 See Documentation/x86/boot.txt and
2772 Documentation/svga.txt.
2773 Use vga=ask for menu.
2774 This is actually a boot loader parameter; the value is
2775 passed to the kernel using a special protocol.
2777 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2778 size of <nn>. This can be used to increase the
2779 minimum size (128MB on x86). It can also be used to
2780 decrease the size and leave more room for directly
2783 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2786 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2789 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2793 Controls the behavior of vsyscalls (i.e. calls to
2794 fixed addresses of 0xffffffffff600x00 from legacy
2795 code). Most statically-linked binaries and older
2796 versions of glibc use these calls. Because these
2797 functions are at fixed addresses, they make nice
2798 targets for exploits that can control RIP.
2800 emulate Vsyscalls turn into traps and are emulated
2803 native [default] Vsyscalls are native syscall
2805 This is a little bit faster than trapping
2806 and makes a few dynamic recompilers work
2807 better than they would in emulation mode.
2808 It also makes exploits much easier to write.
2810 none Vsyscalls don't work at all. This makes
2811 them quite hard to use for exploits but
2812 might break your system.
2814 vt.cur_default= [VT] Default cursor shape.
2815 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2816 the parameters of the <Esc>[?A;B;Cc escape sequence;
2817 see VGA-softcursor.txt. Default: 2 = underline.
2819 vt.default_blu= [VT]
2820 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2821 Change the default blue palette of the console.
2822 This is a 16-member array composed of values
2825 vt.default_grn= [VT]
2826 Format: <green0>,<green1>,<green2>,...,<green15>
2827 Change the default green palette of the console.
2828 This is a 16-member array composed of values
2831 vt.default_red= [VT]
2832 Format: <red0>,<red1>,<red2>,...,<red15>
2833 Change the default red palette of the console.
2834 This is a 16-member array composed of values
2840 Set system-wide default UTF-8 mode for all tty's.
2841 Default is 1, i.e. UTF-8 mode is enabled for all
2842 newly opened terminals.
2844 vt.global_cursor_default=
2847 Set system-wide default for whether a cursor
2848 is shown on new VTs. Default is -1,
2849 i.e. cursors will be created by default unless
2850 overridden by individual drivers. 0 will hide
2851 cursors, 1 will display them.
2853 watchdog timers [HW,WDT] For information on watchdog timers,
2854 see Documentation/watchdog/watchdog-parameters.txt
2855 or other driver-specific files in the
2856 Documentation/watchdog/ directory.
2858 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2859 default x2apic cluster mode on platforms
2862 x86_mrst_timer= [X86-32,APBT]
2863 Choose timer option for x86 Moorestown MID platform.
2864 Two valid options are apbt timer only and lapic timer
2865 plus one apbt timer for broadcast timer.
2866 x86_mrst_timer=apbt_only | lapic_and_apbt
2868 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2869 xd_geo= See header of drivers/block/xd.c.
2871 xen_emul_unplug= [HW,X86,XEN]
2872 Unplug Xen emulated devices
2873 Format: [unplug0,][unplug1]
2874 ide-disks -- unplug primary master IDE devices
2875 aux-ide-disks -- unplug non-primary-master IDE devices
2876 nics -- unplug network devices
2877 all -- unplug all emulated devices (NICs and IDE disks)
2878 unnecessary -- unplugging emulated devices is
2879 unnecessary even if the host did not respond to
2881 never -- do not unplug even if version check succeeds
2883 xirc2ps_cs= [NET,PCMCIA]
2885 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2887 ______________________________________________________________________
2891 Add more DRM drivers.
git.openpandora.org / pandora-kernel.git / blob