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, by default set to 256K.
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 efi_no_storage_paranoia [EFI; X86]
766 Using this parameter you can use more than 50% of
767 your efi variable storage. Use this parameter only if
768 you are really sure that your UEFI does sane gc and
769 fulfills the spec otherwise your board may brick.
771 eisa_irq_edge= [PARISC,HW]
772 See header of drivers/parisc/eisa.c.
775 See comment before function elanfreq_setup() in
776 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
779 Format: {"cfq" | "deadline" | "noop"}
780 See Documentation/block/cfq-iosched.txt and
781 Documentation/block/deadline-iosched.txt for details.
783 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
784 Specifies physical address of start of kernel core
785 image elf header and optionally the size. Generally
786 kexec loader will pass this option to capture kernel.
787 See Documentation/kdump/kdump.txt for details.
789 enable_mtrr_cleanup [X86]
790 The kernel tries to adjust MTRR layout from continuous
791 to discrete, to make X server driver able to add WB
792 entry later. This parameter enables that.
794 enable_timer_pin_1 [X86]
795 Enable PIN 1 of APIC timer
796 Can be useful to work around chipset bugs
797 (in particular on some ATI chipsets).
798 The kernel tries to set a reasonable default.
800 enforcing [SELINUX] Set initial enforcing status.
802 See security/selinux/Kconfig help text.
803 0 -- permissive (log only, no denials).
804 1 -- enforcing (deny and log).
806 Value can be changed at runtime via /selinux/enforce.
809 Disable Error Record Serialization Table (ERST)
812 ether= [HW,NET] Ethernet cards parameters
813 This option is obsoleted by the "netdev=" option, which
814 has equivalent usage. See its documentation for details.
818 Permit 'security.evm' to be updated regardless of
819 current integrity status.
823 fail_make_request=[KNL]
824 General fault injection mechanism.
825 Format: <interval>,<probability>,<space>,<times>
826 See also Documentation/fault-injection/.
829 See Documentation/blockdev/floppy.txt.
831 force_pal_cache_flush
832 [IA-64] Avoid check_sal_cache_flush which may hang on
833 buggy SAL_CACHE_FLUSH implementations. Using this
834 parameter will force ia64_sal_cache_flush to call
835 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
838 [FTRACE] will set and start the specified tracer
839 as early as possible in order to facilitate early
842 ftrace_dump_on_oops[=orig_cpu]
843 [FTRACE] will dump the trace buffers on oops.
844 If no parameter is passed, ftrace will dump
845 buffers of all CPUs, but if you pass orig_cpu, it will
846 dump only the buffer of the CPU that triggered the
849 ftrace_filter=[function-list]
850 [FTRACE] Limit the functions traced by the function
851 tracer at boot up. function-list is a comma separated
852 list of functions. This list can be changed at run
853 time by the set_ftrace_filter file in the debugfs
856 ftrace_notrace=[function-list]
857 [FTRACE] Do not trace the functions specified in
858 function-list. This list can be changed at run time
859 by the set_ftrace_notrace file in the debugfs
862 ftrace_graph_filter=[function-list]
863 [FTRACE] Limit the top level callers functions traced
864 by the function graph tracer at boot up.
865 function-list is a comma separated list of functions
866 that can be changed at run time by the
867 set_graph_function file in the debugfs tracing directory.
870 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
871 support via parallel port (up to 5 devices per port)
872 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
873 See also Documentation/input/joystick-parport.txt
877 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
881 gcov_persist= [GCOV] When non-zero (default), profiling data for
882 kernel modules is saved and remains accessible via
883 debugfs, even when the module is unloaded/reloaded.
884 When zero, profiling data is discarded and associated
885 debugfs files are removed at module unload time.
887 gpt [EFI] Forces disk with valid GPT signature but
888 invalid Protective MBR to be treated as GPT.
890 hashdist= [KNL,NUMA] Large hashes allocated during boot
891 are distributed across NUMA nodes. Defaults on
892 for 64-bit NUMA, off otherwise.
893 Format: 0 | 1 (for off | on)
895 hcl= [IA-64] SGI's Hardware Graph compatibility layer
897 hd= [EIDE] (E)IDE hard drive subsystem geometry
898 Format: <cyl>,<head>,<sect>
901 Disable Hardware Error Source Table (HEST) support;
902 corresponding firmware-first mode error processing
903 logic will be disabled.
905 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
906 size of <nn>. This works even on boxes that have no
907 highmem otherwise. This also works to reduce highmem
908 size on bigger boxes.
910 highres= [KNL] Enable/disable high resolution timer mode.
911 Valid parameters: "on", "off"
915 See Documentation/isdn/README.HiSax.
919 hpet= [X86-32,HPET] option to control HPET usage
920 Format: { enable (default) | disable | force |
922 disable: disable HPET and use PIT instead
923 force: allow force enabled of undocumented chips (ICH4,
925 verbose: show contents of HPET registers during setup
927 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
928 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
929 On x86-64 and powerpc, this option can be specified
930 multiple times interleaved with hugepages= to reserve
931 huge pages of different sizes. Valid pages sizes on
932 x86-64 are 2M (when the CPU supports "pse") and 1G
933 (when the CPU supports the "pdpe1gb" cpuinfo flag)
934 Note that 1GB pages can only be allocated at boot time
935 using hugepages= and not freed afterwards.
937 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
938 terminal devices. Valid values: 0..8
939 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
940 If specified, z/VM IUCV HVC accepts connections
941 from listed z/VM user IDs only.
944 Do not unregister boot console at start. This is only
945 useful for debugging when something happens in the window
946 between unregistering the boot console and initializing
949 i2c_bus= [HW] Override the default board specific I2C bus speed
950 or register an additional I2C bus that is not
951 registered from board initialization code.
955 i8042.debug [HW] Toggle i8042 debug mode
956 i8042.direct [HW] Put keyboard port into non-translated mode
957 i8042.dumbkbd [HW] Pretend that controller can only read data from
958 keyboard and cannot control its state
959 (Don't attempt to blink the leds)
960 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
961 i8042.nokbd [HW] Don't check/create keyboard port
962 i8042.noloop [HW] Disable the AUX Loopback command while probing
964 i8042.nomux [HW] Don't check presence of an active multiplexing
966 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
968 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
969 i8042.reset [HW] Reset the controller during init and cleanup
970 i8042.unlock [HW] Unlock (ignore) the keylock
974 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
975 indicates that the driver is running on unsupported
977 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
978 does not match list of supported models.
980 [HW] Report power status in /proc/i8k
981 (disabled by default)
982 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
985 i915.invert_brightness=
986 [DRM] Invert the sense of the variable that is used to
987 set the brightness of the panel backlight. Normally a
988 brightness value of 0 indicates backlight switched off,
989 and the maximum of the brightness value sets the backlight
990 to maximum brightness. If this parameter is set to 0
991 (default) and the machine requires it, or this parameter
992 is set to 1, a brightness value of 0 sets the backlight
993 to maximum brightness, and the maximum of the brightness
994 value switches the backlight off.
995 -1 -- never invert brightness
997 1 -- force brightness inversion
1000 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1002 ide-core.nodma= [HW] (E)IDE subsystem
1003 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1004 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1005 .cdrom .chs .ignore_cable are additional options
1006 See Documentation/ide/ide.txt.
1008 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1009 Claim all unknown PCI IDE storage controllers.
1012 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
1013 Poll forces a polling idle loop that can slightly
1014 improve the performance of waking up a idle CPU, but
1015 will use a lot of power and make the system run hot.
1017 idle=mwait: On systems which support MONITOR/MWAIT but
1018 the kernel chose to not use it because it doesn't save
1019 as much power as a normal idle loop, use the
1020 MONITOR/MWAIT idle loop anyways. Performance should be
1021 the same as idle=poll.
1022 idle=halt: Halt is forced to be used for CPU idle.
1023 In such case C2/C3 won't be used again.
1024 idle=nomwait: Disable mwait for CPU C-states
1026 ignore_loglevel [KNL]
1027 Ignore loglevel setting - this will print /all/
1028 kernel messages to the console. Useful for debugging.
1029 We also add it as printk module parameter, so users
1030 could change it dynamically, usually by
1031 /sys/module/printk/parameters/ignore_loglevel.
1033 ihash_entries= [KNL]
1034 Set number of hash buckets for inode cache.
1037 Format: { "0" | "1" }
1038 0 -- integrity auditing messages. (Default)
1039 1 -- enable informational integrity auditing messages.
1042 Format: { "sha1" | "md5" }
1046 Load a policy which meets the needs of the Trusted
1047 Computing Base. This means IMA will measure all
1048 programs exec'd, files mmap'd for exec, and all files
1049 opened for read by uid=0.
1053 Run specified binary instead of /sbin/init as init
1056 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1057 for working out where the kernel is dying during
1060 initrd= [BOOT] Specify the location of the initial ramdisk
1062 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1065 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1067 Enable intel iommu driver.
1069 Disable intel iommu driver.
1070 igfx_off [Default Off]
1071 By default, gfx is mapped as normal device. If a gfx
1072 device has a dedicated DMAR unit, the DMAR unit is
1073 bypassed by not enabling DMAR with this option. In
1074 this case, gfx device will use physical address for
1077 With this option iommu will not optimize to look
1078 for io virtual address below 32-bit forcing dual
1079 address cycle on pci bus for cards supporting greater
1080 than 32-bit addressing. The default is to look
1081 for translation below 32-bit and if not available
1082 then look in the higher range.
1083 strict [Default Off]
1084 With this option on every unmap_single operation will
1085 result in a hardware IOTLB flush operation as opposed
1086 to batching them for performance.
1087 sp_off [Default Off]
1088 By default, super page will be supported if Intel IOMMU
1089 has the capability. With this option, super page will
1091 intremap= [X86-64, Intel-IOMMU]
1092 on enable Interrupt Remapping (default)
1093 off disable Interrupt Remapping
1094 nosid disable Source ID checking
1096 BIOS x2APIC opt-out request will be ignored
1100 iomem= Disable strict checking of access to MMIO memory
1101 strict regions from userspace.
1117 io7= [HW] IO7 for Marvel based alpha systems
1118 See comment before marvel_specify_io7 in
1119 arch/alpha/kernel/core_marvel.c.
1121 io_delay= [X86] I/O delay method
1123 Standard port 0x80 based delay
1125 Alternate port 0xed based delay (needed on some systems)
1127 Simple two microseconds delay
1132 See Documentation/filesystems/nfs/nfsroot.txt.
1134 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1135 See comment before ip2_setup() in
1136 drivers/char/ip2/ip2base.c.
1139 When an interrupt is not handled search all handlers
1140 for it. Intended to get systems with badly broken
1144 When an interrupt is not handled search all handlers
1145 for it. Also check all handlers each timer
1146 interrupt. Intended to get systems with badly broken
1150 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1152 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1154 <cpu number>,...,<cpu number>
1156 <cpu number>-<cpu number>
1157 (must be a positive range in ascending order)
1159 <cpu number>,...,<cpu number>-<cpu number>
1161 This option can be used to specify one or more CPUs
1162 to isolate from the general SMP balancing and scheduling
1163 algorithms. You can move a process onto or off an
1164 "isolated" CPU via the CPU affinity syscalls or cpuset.
1165 <cpu number> begins at 0 and the maximum value is
1166 "number of CPUs in system - 1".
1168 This option is the preferred way to isolate CPUs. The
1169 alternative -- manually setting the CPU mask of all
1170 tasks in the system -- can cause problems and
1171 suboptimal load balancer performance.
1175 js= [HW,JOY] Analog joystick
1176 See Documentation/input/joystick.txt.
1180 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1181 specifies the amount of memory usable by the kernel
1182 for non-movable allocations. The requested amount is
1183 spread evenly throughout all nodes in the system. The
1184 remaining memory in each node is used for Movable
1185 pages. In the event, a node is too small to have both
1186 kernelcore and Movable pages, kernelcore pages will
1187 take priority and other nodes will have a larger number
1188 of kernelcore pages. The Movable zone is used for the
1189 allocation of pages that may be reclaimed or moved
1190 by the page migration subsystem. This means that
1191 HugeTLB pages may not be allocated from this zone.
1192 Note that allocations like PTEs-from-HighMem still
1193 use the HighMem zone if it exists, and the Normal
1194 zone if it does not.
1196 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1197 Format: <Controller#>[,poll interval]
1198 The controller # is the number of the ehci usb debug
1199 port as it is probed via PCI. The poll interval is
1200 optional and is the number seconds in between
1201 each poll cycle to the debug port in case you need
1202 the functionality for interrupting the kernel with
1203 gdb or control-c on the dbgp connection. When
1204 not using this parameter you use sysrq-g to break into
1205 the kernel debugger.
1207 kgdboc= [KGDB,HW] kgdb over consoles.
1208 Requires a tty driver that supports console polling,
1209 or a supported polling keyboard driver (non-usb).
1210 Serial only format: <serial_device>[,baud]
1211 keyboard only format: kbd
1212 keyboard and serial format: kbd,<serial_device>[,baud]
1213 Optional Kernel mode setting:
1214 kms, kbd format: kms,kbd
1215 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1217 kgdbwait [KGDB] Stop kernel execution and enter the
1218 kernel debugger at the earliest opportunity.
1220 kmac= [MIPS] korina ethernet MAC address.
1221 Configure the RouterBoard 532 series on-chip
1222 Ethernet adapter MAC address.
1224 kmemleak= [KNL] Boot-time kmemleak enable/disable
1225 Valid arguments: on, off
1228 kstack=N [X86] Print N words from the kernel stack
1231 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1232 Default is 0 (don't ignore, but inject #GP)
1234 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1235 Default is 1 (enabled)
1237 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1241 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1242 Default is 1 (enabled)
1244 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1246 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1248 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1249 (virtualized MMU) support on capable Intel chips.
1250 Default is 1 (enabled)
1252 kvm-intel.emulate_invalid_guest_state=
1253 [KVM,Intel] Enable emulation of invalid guest states
1254 Default is 0 (disabled)
1256 kvm-intel.flexpriority=
1257 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1258 Default is 1 (enabled)
1261 [KVM,Intel] Enable VMX nesting (nVMX).
1262 Default is 0 (disabled)
1264 kvm-intel.unrestricted_guest=
1265 [KVM,Intel] Disable unrestricted guest feature
1266 (virtualized real and unpaged mode) on capable
1267 Intel chips. Default is 1 (enabled)
1269 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1270 feature (tagged TLBs) on capable Intel chips.
1271 Default is 1 (enabled)
1277 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1280 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1283 libata.dma= [LIBATA] DMA control
1284 libata.dma=0 Disable all PATA and SATA DMA
1285 libata.dma=1 PATA and SATA Disk DMA only
1286 libata.dma=2 ATAPI (CDROM) DMA only
1287 libata.dma=4 Compact Flash DMA only
1288 Combinations also work, so libata.dma=3 enables DMA
1289 for disks and CDROMs, but not CFs.
1291 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1292 libata.ignore_hpa=0 keep BIOS limits (default)
1293 libata.ignore_hpa=1 ignore limits, using full disk
1295 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1299 libata.force= [LIBATA] Force configurations. The format is comma
1300 separated list of "[ID:]VAL" where ID is
1301 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1302 matching port, link or device. Basically, it matches
1303 the ATA ID string printed on console by libata. If
1304 the whole ID part is omitted, the last PORT and DEVICE
1305 values are used. If ID hasn't been specified yet, the
1306 configuration applies to all ports, links and devices.
1308 If only DEVICE is omitted, the parameter applies to
1309 the port and all links and devices behind it. DEVICE
1310 number of 0 either selects the first device or the
1311 first fan-out link behind PMP device. It does not
1312 select the host link. DEVICE number of 15 selects the
1313 host link and device attached to it.
1315 The VAL specifies the configuration to force. As long
1316 as there's no ambiguity shortcut notation is allowed.
1317 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1318 The following configurations can be forced.
1320 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1321 Any ID with matching PORT is used.
1323 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1325 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1326 udma[/][16,25,33,44,66,100,133] notation is also
1329 * [no]ncq: Turn on or off NCQ.
1331 * nohrst, nosrst, norst: suppress hard, soft
1334 * dump_id: dump IDENTIFY data.
1336 * disable: Disable this device.
1338 If there are multiple matching configurations changing
1339 the same attribute, the last one is used.
1341 memblock=debug [KNL] Enable memblock debug messages.
1343 load_ramdisk= [RAM] List of ramdisks to load from floppy
1344 See Documentation/blockdev/ramdisk.txt.
1346 lockd.nlm_grace_period=P [NFS] Assign grace period.
1349 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1352 lockd.nlm_timeout=T [NFS] Assign timeout value.
1355 lockd.nlm_udpport=M [NFS] Assign UDP port.
1358 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1361 loglevel= All Kernel Messages with a loglevel smaller than the
1362 console loglevel will be printed to the console. It can
1363 also be changed with klogd or other programs. The
1364 loglevels are defined as follows:
1366 0 (KERN_EMERG) system is unusable
1367 1 (KERN_ALERT) action must be taken immediately
1368 2 (KERN_CRIT) critical conditions
1369 3 (KERN_ERR) error conditions
1370 4 (KERN_WARNING) warning conditions
1371 5 (KERN_NOTICE) normal but significant condition
1372 6 (KERN_INFO) informational
1373 7 (KERN_DEBUG) debug-level messages
1375 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1376 in bytes. n must be a power of two. The default
1377 size is set in the kernel config file.
1379 logo.nologo [FB] Disables display of the built-in Linux logo.
1380 This may be used to provide more screen space for
1381 kernel log messages and is useful when debugging
1382 kernel boot problems.
1384 lp=0 [LP] Specify parallel ports to use, e.g,
1385 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1386 lp=reset first parallel port). 'lp=0' disables the
1387 lp=auto printer driver. 'lp=reset' (which can be
1388 specified in addition to the ports) causes
1389 attached printers to be reset. Using
1390 lp=port1,port2,... specifies the parallel ports
1391 to associate lp devices with, starting with
1392 lp0. A port specification may be 'none' to skip
1393 that lp device, or a parport name such as
1394 'parport0'. Specifying 'lp=auto' instead of a
1395 port specification list means that device IDs
1396 from each port should be examined, to see if
1397 an IEEE 1284-compliant printer is attached; if
1398 so, the driver will manage that printer.
1399 See also header of drivers/char/lp.c.
1402 Sets loops_per_jiffy to given constant, thus avoiding
1403 time-consuming boot-time autodetection (up to 250 ms per
1404 CPU). 0 enables autodetection (default). To determine
1405 the correct value for your kernel, boot with normal
1406 autodetection and see what value is printed. Note that
1407 on SMP systems the preset will be applied to all CPUs,
1408 which is likely to cause problems if your CPUs need
1409 significantly divergent settings. An incorrect value
1410 will cause delays in the kernel to be wrong, leading to
1411 unpredictable I/O errors and other breakage. Although
1412 unlikely, in the extreme case this might damage your
1416 Format: <io>,<irq>,<dma>
1418 machvec= [IA-64] Force the use of a particular machine-vector
1419 (machvec) in a generic kernel.
1420 Example: machvec=hpzx1_swiotlb
1422 machtype= [Loongson] Share the same kernel image file between different
1424 Example: machtype=lemote-yeeloong-2f-7inch
1426 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1427 than or equal to this physical address is ignored.
1429 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1430 should make use of. maxcpus=n : n >= 0 limits the
1431 kernel to using 'n' processors. n=0 is a special case,
1432 it is equivalent to "nosmp", which also disables
1435 max_loop= [LOOP] The number of loop block devices that get
1436 (loop.max_loop) unconditionally pre-created at init time. The default
1437 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1438 of statically allocating a predefined number, loop
1439 devices can be requested on-demand with the
1440 /dev/loop-control interface.
1444 mce [X86-32] Machine Check Exception
1446 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1448 md= [HW] RAID subsystems devices and level
1449 See Documentation/md.txt.
1452 Format: <first>,<last>
1453 Specifies range of consoles to be captured by the MDA.
1455 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1456 Amount of memory to be used when the kernel is not able
1457 to see the whole system memory or for test.
1458 [X86-32] Use together with memmap= to avoid physical
1459 address space collisions. Without memmap= PCI devices
1460 could be placed at addresses belonging to unused RAM.
1462 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1466 [KNL,SH] Allow user to override the default size for
1467 per-device physically contiguous DMA buffers.
1469 memmap=exactmap [KNL,X86] Enable setting of an exact
1470 E820 memory map, as specified by the user.
1471 Such memmap=exactmap lines can be constructed based on
1472 BIOS output or other requirements. See the memmap=nn@ss
1475 memmap=nn[KMG]@ss[KMG]
1476 [KNL] Force usage of a specific region of memory
1477 Region of memory to be used, from ss to ss+nn.
1479 memmap=nn[KMG]#ss[KMG]
1480 [KNL,ACPI] Mark specific memory as ACPI data.
1481 Region of memory to be used, from ss to ss+nn.
1483 memmap=nn[KMG]$ss[KMG]
1484 [KNL,ACPI] Mark specific memory as reserved.
1485 Region of memory to be used, from ss to ss+nn.
1486 Example: Exclude memory from 0x18690000-0x1869ffff
1487 memmap=64K$0x18690000
1489 memmap=0x10000$0x18690000
1491 memory_corruption_check=0/1 [X86]
1492 Some BIOSes seem to corrupt the first 64k of
1493 memory when doing things like suspend/resume.
1494 Setting this option will scan the memory
1495 looking for corruption. Enabling this will
1496 both detect corruption and prevent the kernel
1497 from using the memory being corrupted.
1498 However, its intended as a diagnostic tool; if
1499 repeatable BIOS-originated corruption always
1500 affects the same memory, you can use memmap=
1501 to prevent the kernel from using that memory.
1503 memory_corruption_check_size=size [X86]
1504 By default it checks for corruption in the low
1505 64k, making this memory unavailable for normal
1506 use. Use this parameter to scan for
1507 corruption in more or less memory.
1509 memory_corruption_check_period=seconds [X86]
1510 By default it checks for corruption every 60
1511 seconds. Use this parameter to check at some
1512 other rate. 0 disables periodic checking.
1514 memtest= [KNL,X86] Enable memtest
1516 default : 0 <disable>
1517 Specifies the number of memtest passes to be
1518 performed. Each pass selects another test
1519 pattern from a given set of patterns. Memtest
1520 fills the memory with this pattern, validates
1521 memory contents and reserves bad memory
1522 regions that are detected.
1524 meye.*= [HW] Set MotionEye Camera parameters
1525 See Documentation/video4linux/meye.txt.
1527 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1528 Multi-Function General Purpose Timers on AMD Geode
1531 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1532 the BIOS has incorrectly applied a workaround. TinyBIOS
1533 version 0.98 is known to be affected, 0.99 fixes the
1534 problem by letting the user disable the workaround.
1538 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1539 physical address is ignored.
1541 mini2440= [ARM,HW,KNL]
1542 Format:[0..2][b][c][t]
1544 MINI2440 configuration specification:
1545 0 - The attached screen is the 3.5" TFT
1546 1 - The attached screen is the 7" TFT
1547 2 - The VGA Shield is attached (1024x768)
1548 Leaving out the screen size parameter will not load
1549 the TFT driver, and the framebuffer will be left
1551 b - Enable backlight. The TFT backlight pin will be
1552 linked to the kernel VESA blanking code and a GPIO
1553 LED. This parameter is not necessary when using the
1555 c - Enable the s3c camera interface.
1556 t - Reserved for enabling touchscreen support. The
1557 touchscreen support is not enabled in the mainstream
1558 kernel as of 2.6.30, a preliminary port can be found
1559 in the "bleeding edge" mini2440 support kernel at
1560 http://repo.or.cz/w/linux-2.6/mini2440.git
1563 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1564 parameter allows control of the logging verbosity for
1565 the additional memory initialisation checks. A value
1566 of 0 disables mminit logging and a level of 4 will
1567 log everything. Information is printed at KERN_DEBUG
1568 so loglevel=8 may also need to be specified.
1571 [MOUSE] Maximum time between finger touching and
1572 leaving touchpad surface for touch to be considered
1573 a tap and be reported as a left button click (for
1574 touchpads working in absolute mode only).
1576 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1577 reporting absolute coordinates, such as tablets
1578 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1579 reporting absolute coordinates, such as tablets
1581 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1582 is similar to kernelcore except it specifies the
1583 amount of memory used for migratable allocations.
1584 If both kernelcore and movablecore is specified,
1585 then kernelcore will be at *least* the specified
1586 value but may be more. If movablecore on its own
1587 is specified, the administrator must be careful
1588 that the amount of memory usable for all allocations
1591 MTD_Partition= [MTD]
1592 Format: <name>,<region-number>,<size>,<offset>
1594 MTD_Region= [MTD] Format:
1595 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1598 See drivers/mtd/cmdlinepart.c.
1600 multitce=off [PPC] This parameter disables the use of the pSeries
1601 firmware feature for updating multiple TCE entries
1604 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1606 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1608 boundary - index of last SLC block on Flex-OneNAND.
1609 The remaining blocks are configured as MLC blocks.
1610 lock - Configure if Flex-OneNAND boundary should be locked.
1611 Once locked, the boundary cannot be changed.
1612 1 indicates lock status, 0 indicates unlock status.
1615 ARM/S3C2412 JIVE boot control
1617 See arch/arm/mach-s3c2412/mach-jive.c
1619 mtouchusb.raw_coordinates=
1620 [HW] Make the MicroTouch USB driver use raw coordinates
1621 ('y', default) or cooked coordinates ('n')
1623 mtrr_chunk_size=nn[KMG] [X86]
1624 used for mtrr cleanup. It is largest continuous chunk
1625 that could hold holes aka. UC entries.
1627 mtrr_gran_size=nn[KMG] [X86]
1628 Used for mtrr cleanup. It is granularity of mtrr block.
1630 Large value could prevent small alignment from
1633 mtrr_spare_reg_nr=n [X86]
1635 Range: 0,7 : spare reg number
1637 Used for mtrr cleanup. It is spare mtrr entries number.
1638 Set to 2 or more if your graphical card needs more.
1640 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1642 netdev= [NET] Network devices parameters
1643 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1644 Note that mem_start is often overloaded to mean
1645 something different and driver-specific.
1646 This usage is only documented in each driver source
1650 [NETFILTER] Enable connection tracking flow accounting
1651 0 to disable accounting
1652 1 to enable accounting
1655 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1656 See Documentation/filesystems/nfs/nfsroot.txt.
1658 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1659 See Documentation/filesystems/nfs/nfsroot.txt.
1661 nfsrootdebug [NFS] enable nfsroot debugging messages.
1662 See Documentation/filesystems/nfs/nfsroot.txt.
1664 nfs.callback_tcpport=
1665 [NFS] set the TCP port on which the NFSv4 callback
1666 channel should listen.
1669 [NFS] sets the pathname to the program which is used
1670 to update the NFS client cache entries.
1672 nfs.cache_getent_timeout=
1673 [NFS] sets the timeout after which an attempt to
1674 update a cache entry is deemed to have failed.
1676 nfs.idmap_cache_timeout=
1677 [NFS] set the maximum lifetime for idmapper cache
1681 [NFS] enable 64-bit inode numbers.
1682 If zero, the NFS client will fake up a 32-bit inode
1683 number for the readdir() and stat() syscalls instead
1684 of returning the full 64-bit number.
1685 The default is to return 64-bit inode numbers.
1687 nfs.nfs4_disable_idmapping=
1688 [NFSv4] When set, this option disables the NFSv4
1689 idmapper on the client, but only if the mount
1690 is using the 'sec=sys' security flavour. This may
1691 make migration from legacy NFSv2/v3 systems easier
1692 provided that the server has the appropriate support.
1693 The default is to always enable NFSv4 idmapping.
1695 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1696 when a NMI is triggered.
1697 Format: [state][,regs][,debounce][,die]
1699 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1700 Format: [panic,][nopanic,][num]
1702 0 - turn nmi_watchdog off
1703 When panic is specified, panic when an NMI watchdog
1704 timeout occurs (or 'nopanic' to override the opposite
1706 This is useful when you use a panic=... timeout and
1707 need the box quickly up again.
1709 netpoll.carrier_timeout=
1710 [NET] Specifies amount of time (in seconds) that
1711 netpoll should wait for a carrier. By default netpoll
1714 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1715 emulation library even if a 387 maths coprocessor
1719 [HW] Never suspend the console
1720 Disable suspending of consoles during suspend and
1721 hibernate operations. Once disabled, debugging
1722 messages can reach various consoles while the rest
1723 of the system is being put to sleep (ie, while
1724 debugging driver suspend/resume hooks). This may
1725 not work reliably with all consoles, but is known
1726 to work with serial and VGA consoles.
1727 To facilitate more flexible debugging, we also add
1728 console_suspend, a printk module parameter to control
1729 it. Users could use console_suspend (usually
1730 /sys/module/printk/parameters/console_suspend) to
1731 turn on/off it dynamically.
1733 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1734 caches in the slab allocator. Saves per-node memory,
1735 but will impact performance.
1739 noapic [SMP,APIC] Tells the kernel to not make use of any
1740 IOAPICs that may be present in the system.
1742 noautogroup Disable scheduler automatic task group creation.
1744 nobats [PPC] Do not use BATs for mapping kernel lowmem
1745 on "Classic" PPC cores.
1749 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1751 nodelayacct [KNL] Disable per-task delay accounting
1753 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1755 nodsp [SH] Disable hardware DSP at boot time.
1757 noefi [X86] Disable EFI runtime services support.
1762 On X86-32 available only on PAE configured kernels.
1763 noexec=on: enable non-executable mappings (default)
1764 noexec=off: disable non-executable mappings
1767 Disable SMEP (Supervisor Mode Execution Protection)
1768 even if it is supported by processor.
1771 This affects only 32-bit executables.
1772 noexec32=on: enable non-executable mappings (default)
1773 read doesn't imply executable mappings
1774 noexec32=off: disable non-executable mappings
1775 read implies executable mappings
1777 nofpu [SH] Disable hardware FPU at boot time.
1779 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1780 register save and restore. The kernel will only save
1781 legacy floating-point registers on task switch.
1783 noxsave [BUGS=X86] Disables x86 extended register state save
1784 and restore using xsave. The kernel will fallback to
1785 enabling legacy floating-point and sse state.
1787 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1788 wfi(ARM) instruction doesn't work correctly and not to
1789 use it. This is also useful when using JTAG debugger.
1791 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1792 instruction doesn't work correctly and not to
1795 no_file_caps Tells the kernel not to honor file capabilities. The
1796 only way then for a file to be executed with privilege
1797 is to be setuid root or executed by root.
1799 nohalt [IA-64] Tells the kernel not to use the power saving
1800 function PAL_HALT_LIGHT when idle. This increases
1801 power-consumption. On the positive side, it reduces
1802 interrupt wake-up latency, which may improve performance
1803 in certain environments such as networked servers or
1806 nohz= [KNL] Boottime enable/disable dynamic ticks
1807 Valid arguments: on, off
1810 noiotrap [SH] Disables trapped I/O port accesses.
1812 noirqdebug [X86-32] Disables the code which attempts to detect and
1813 disable unhandled interrupt sources.
1815 no_timer_check [X86,APIC] Disables the code which tests for
1816 broken timer IRQ sources.
1818 noisapnp [ISAPNP] Disables ISA PnP code.
1820 noinitrd [RAM] Tells the kernel not to load any configured
1823 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1825 [Deprecated - use intremap=off]
1829 nojitter [IA-64] Disables jitter checking for ITC timers.
1831 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1833 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1836 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1837 steal time is computed, but won't influence scheduler
1840 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1842 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1844 noltlbs [PPC] Do not use large page/tlb entries for kernel
1845 lowmem mapping on PPC40x.
1847 nomca [IA-64] Disable machine check abort handling
1849 nomce [X86-32] Machine Check Exception
1851 nomfgpt [X86-32] Disable Multi-Function General Purpose
1852 Timer usage (for AMD Geode machines).
1854 nopat [X86] Disable PAT (page attribute table extension of
1855 pagetables) support.
1857 norandmaps Don't use address space randomization. Equivalent to
1858 echo 0 > /proc/sys/kernel/randomize_va_space
1860 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1862 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1863 with UP alternatives
1865 noresidual [PPC] Don't use residual data on PReP machines.
1867 nordrand [X86] Disable the direct use of the RDRAND
1868 instruction even if it is supported by the
1869 processor. RDRAND is still available to user
1872 noresume [SWSUSP] Disables resume and restores original swap
1875 no-scroll [VGA] Disables scrollback.
1876 This is required for the Braillex ib80-piezo Braille
1877 reader made by F.H. Papenmeier (Germany).
1881 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1883 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1884 and disable the IO APIC. legacy for "maxcpus=0".
1886 nosoftlockup [KNL] Disable the soft-lockup detector.
1888 nosync [HW,M68K] Disables sync negotiation for all devices.
1890 notsc [BUGS=X86-32] Disable Time Stamp Counter
1892 nousb [USB] Disable the USB subsystem
1894 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1898 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1900 nptcg= [IA-64] Override max number of concurrent global TLB
1901 purges which is reported from either PAL_VM_SUMMARY or
1904 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1905 could support. nr_cpus=n : n >= 1 limits the kernel to
1906 supporting 'n' processors. Later in runtime you can not
1907 use hotplug cpu feature to put more cpu back to online.
1908 just like you compile the kernel NR_CPUS=n
1910 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1912 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1913 one of ['zone', 'node', 'default'] can be specified
1914 This can be set from sysctl after boot.
1915 See Documentation/sysctl/vm.txt for details.
1917 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1918 See Documentation/debugging-via-ohci1394.txt for more
1921 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1922 Rather than timing out after 20 ms if an EC
1923 command is not properly ACKed, override the length
1924 of the timeout. We have interrupts disabled while
1925 waiting for the ACK, so if this is set too high
1926 interrupts *may* be lost!
1928 omap_mux= [OMAP] Override bootloader pin multiplexing.
1929 Format: <mux_mode0.mode_name=value>...
1930 For example, to override I2C bus2:
1931 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1933 oprofile.timer= [HW]
1934 Use timer interrupt instead of performance counters
1936 oprofile.cpu_type= Force an oprofile cpu type
1937 This might be useful if you have an older oprofile
1938 userland or if you want common events.
1939 Format: { arch_perfmon }
1940 arch_perfmon: [X86] Force use of architectural
1941 perfmon on Intel CPUs instead of the
1942 CPU specific event set.
1944 oops=panic Always panic on oopses. Default is to just kill the
1945 process, but there is a small probability of
1946 deadlocking the machine.
1947 This will also cause panics on machine check exceptions.
1948 Useful together with panic=30 to trigger a reboot.
1951 See Documentation/sound/oss/oss-parameters.txt
1953 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1954 timeout > 0: seconds before rebooting
1955 timeout = 0: wait forever
1956 timeout < 0: reboot immediately
1959 parkbd.port= [HW] Parallel port number the keyboard adapter is
1960 connected to, default is 0.
1962 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1963 0 for XT, 1 for AT (default is AT).
1966 parport= [HW,PPT] Specify parallel ports. 0 disables.
1967 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1968 Use 'auto' to force the driver to use any
1969 IRQ/DMA settings detected (the default is to
1970 ignore detected IRQ/DMA settings because of
1971 possible conflicts). You can specify the base
1972 address, IRQ, and DMA settings; IRQ and DMA
1973 should be numbers, or 'auto' (for using detected
1974 settings on that particular port), or 'nofifo'
1975 (to avoid using a FIFO even if it is detected).
1976 Parallel ports are assigned in the order they
1977 are specified on the command line, starting
1980 parport_init_mode= [HW,PPT]
1981 Configure VIA parallel port to operate in
1982 a specific mode. This is necessary on Pegasos
1983 computer where firmware has no options for setting
1984 up parallel port mode and sets it to spp.
1985 Currently this function knows 686a and 8231 chips.
1986 Format: [spp|ps2|epp|ecp|ecpepp]
1989 Halt all CPUs after the first oops has been printed for
1990 the specified number of seconds. This is to be used if
1991 your oopses keep scrolling off the screen.
1996 See header of drivers/block/paride/pcd.c.
1997 See also Documentation/blockdev/paride.txt.
1999 pci=option[,option...] [PCI] various PCI subsystem options:
2000 earlydump [X86] dump PCI config space before the kernel
2002 off [X86] don't probe for the PCI bus
2003 bios [X86-32] force use of PCI BIOS, don't access
2004 the hardware directly. Use this if your machine
2005 has a non-standard PCI host bridge.
2006 nobios [X86-32] disallow use of PCI BIOS, only direct
2007 hardware access methods are allowed. Use this
2008 if you experience crashes upon bootup and you
2009 suspect they are caused by the BIOS.
2010 conf1 [X86] Force use of PCI Configuration
2012 conf2 [X86] Force use of PCI Configuration
2014 noaer [PCIE] If the PCIEAER kernel config parameter is
2015 enabled, this kernel boot option can be used to
2016 disable the use of PCIE advanced error reporting.
2017 nodomains [PCI] Disable support for multiple PCI
2018 root domains (aka PCI segments, in ACPI-speak).
2019 nommconf [X86] Disable use of MMCONFIG for PCI
2021 check_enable_amd_mmconf [X86] check for and enable
2022 properly configured MMIO access to PCI
2023 config space on AMD family 10h CPU
2024 nomsi [MSI] If the PCI_MSI kernel config parameter is
2025 enabled, this kernel boot option can be used to
2026 disable the use of MSI interrupts system-wide.
2027 noioapicquirk [APIC] Disable all boot interrupt quirks.
2028 Safety option to keep boot IRQs enabled. This
2029 should never be necessary.
2030 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2031 primary IO-APIC for bridges that cannot disable
2032 boot IRQs. This fixes a source of spurious IRQs
2033 when the system masks IRQs.
2034 noioapicreroute [APIC] Disable workaround that uses the
2035 boot IRQ equivalent of an IRQ that connects to
2036 a chipset where boot IRQs cannot be disabled.
2037 The opposite of ioapicreroute.
2038 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2039 routing table. These calls are known to be buggy
2040 on several machines and they hang the machine
2041 when used, but on other computers it's the only
2042 way to get the interrupt routing table. Try
2043 this option if the kernel is unable to allocate
2044 IRQs or discover secondary PCI buses on your
2046 rom [X86] Assign address space to expansion ROMs.
2047 Use with caution as certain devices share
2048 address decoders between ROMs and other
2050 norom [X86] Do not assign address space to
2051 expansion ROMs that do not already have
2052 BIOS assigned address ranges.
2053 nobar [X86] Do not assign address space to the
2054 BARs that weren't assigned by the BIOS.
2055 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2056 assigned automatically to PCI devices. You can
2057 make the kernel exclude IRQs of your ISA cards
2059 pirqaddr=0xAAAAA [X86] Specify the physical address
2060 of the PIRQ table (normally generated
2061 by the BIOS) if it is outside the
2062 F0000h-100000h range.
2063 lastbus=N [X86] Scan all buses thru bus #N. Can be
2064 useful if the kernel is unable to find your
2065 secondary buses and you want to tell it
2066 explicitly which ones they are.
2067 assign-busses [X86] Always assign all PCI bus
2068 numbers ourselves, overriding
2069 whatever the firmware may have done.
2070 usepirqmask [X86] Honor the possible IRQ mask stored
2071 in the BIOS $PIR table. This is needed on
2072 some systems with broken BIOSes, notably
2073 some HP Pavilion N5400 and Omnibook XE3
2074 notebooks. This will have no effect if ACPI
2075 IRQ routing is enabled.
2076 noacpi [X86] Do not use ACPI for IRQ routing
2077 or for PCI scanning.
2078 use_crs [X86] Use PCI host bridge window information
2079 from ACPI. On BIOSes from 2008 or later, this
2080 is enabled by default. If you need to use this,
2081 please report a bug.
2082 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2083 If you need to use this, please report a bug.
2084 routeirq Do IRQ routing for all PCI devices.
2085 This is normally done in pci_enable_device(),
2086 so this option is a temporary workaround
2087 for broken drivers that don't call it.
2088 skip_isa_align [X86] do not align io start addr, so can
2089 handle more pci cards
2090 firmware [ARM] Do not re-enumerate the bus but instead
2091 just use the configuration from the
2092 bootloader. This is currently used on
2093 IXP2000 systems where the bus has to be
2094 configured a certain way for adjunct CPUs.
2095 noearly [X86] Don't do any early type 1 scanning.
2096 This might help on some broken boards which
2097 machine check when some devices' config space
2098 is read. But various workarounds are disabled
2099 and some IOMMU drivers will not work.
2100 bfsort Sort PCI devices into breadth-first order.
2101 This sorting is done to get a device
2102 order compatible with older (<= 2.4) kernels.
2103 nobfsort Don't sort PCI devices into breadth-first order.
2104 cbiosize=nn[KMG] The fixed amount of bus space which is
2105 reserved for the CardBus bridge's IO window.
2106 The default value is 256 bytes.
2107 cbmemsize=nn[KMG] The fixed amount of bus space which is
2108 reserved for the CardBus bridge's memory
2109 window. The default value is 64 megabytes.
2112 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2113 Specifies alignment and device to reassign
2114 aligned memory resources.
2115 If <order of align> is not specified,
2116 PAGE_SIZE is used as alignment.
2117 PCI-PCI bridge can be specified, if resource
2118 windows need to be expanded.
2119 ecrc= Enable/disable PCIe ECRC (transaction layer
2120 end-to-end CRC checking).
2121 bios: Use BIOS/firmware settings. This is the
2125 realloc reallocate PCI resources if allocations done by BIOS
2128 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2131 force Enable ASPM even on devices that claim not to support it.
2132 WARNING: Forcing ASPM on may cause system lockups.
2134 pcie_ports= [PCIE] PCIe ports handling:
2135 auto Ask the BIOS whether or not to use native PCIe services
2136 associated with PCIe ports (PME, hot-plug, AER). Use
2137 them only if that is allowed by the BIOS.
2138 native Use native PCIe services associated with PCIe ports
2140 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2143 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2144 nomsi Do not use MSI for native PCIe PME signaling (this makes
2145 all PCIe root ports use INTx for all services).
2147 pcmv= [HW,PCMCIA] BadgePAD 4
2150 See Documentation/blockdev/paride.txt.
2152 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2155 See arch/parisc/kernel/pdc_chassis.c
2157 percpu_alloc= Select which percpu first chunk allocator to use.
2158 Currently supported values are "embed" and "page".
2159 Archs may support subset or none of the selections.
2160 See comments in mm/percpu.c for details on each
2161 allocator. This parameter is primarily for debugging
2162 and performance comparison.
2165 See Documentation/blockdev/paride.txt.
2168 See Documentation/blockdev/paride.txt.
2170 pirq= [SMP,APIC] Manual mp-table setup
2171 See Documentation/x86/i386/IO-APIC.txt.
2173 plip= [PPT,NET] Parallel port network link
2174 Format: { parport<nr> | timid | 0 }
2175 See also Documentation/parport.txt.
2177 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2178 Override pmtimer IOPort with a hex value.
2182 Enable PNP debug messages (depends on the
2183 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2184 via /sys/module/pnp/parameters/debug. We always show
2185 current resource usage; turning this on also shows
2186 possible settings and some assignment information.
2192 { on | off | curr | res | no-curr | no-res }
2195 [ISAPNP] Exclude IRQs for the autoconfiguration
2198 [ISAPNP] Exclude DMAs for the autoconfiguration
2200 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2201 Ranges are in pairs (I/O port base and size).
2204 [ISAPNP] Exclude memory regions for the
2206 Ranges are in pairs (memory base and size).
2208 ports= [IP_VS_FTP] IPVS ftp helper module
2210 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2212 Format: <port>,<port>....
2214 print-fatal-signals=
2215 [KNL] debug: print fatal signals
2217 If enabled, warn about various signal handling
2218 related application anomalies: too many signals,
2219 too many POSIX.1 timers, fatal signals causing a
2222 If you hit the warning due to signal overflow,
2223 you might want to try "ulimit -i unlimited".
2227 printk.time= Show timing data prefixed to each printk message line
2228 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2230 processor.max_cstate= [HW,ACPI]
2231 Limit processor to maximum C-state
2232 max_cstate=9 overrides any DMI blacklist limit.
2234 processor.nocst [HW,ACPI]
2235 Ignore the _CST method to determine C-states,
2236 instead using the legacy FADT method
2238 profile= [KNL] Enable kernel profiling via /proc/profile
2239 Format: [schedule,]<number>
2240 Param: "schedule" - profile schedule points.
2241 Param: <number> - step/bucket size as a power of 2 for
2242 statistical time based profiling.
2243 Param: "sleep" - profile D-state sleeping (millisecs).
2244 Requires CONFIG_SCHEDSTATS
2245 Param: "kvm" - profile VM exits.
2247 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2249 See Documentation/blockdev/ramdisk.txt.
2251 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2252 probe for; one of (bare|imps|exps|lifebook|any).
2253 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2255 psmouse.resetafter= [HW,MOUSE]
2256 Try to reset the device after so many bad packets
2259 [HW,MOUSE] Set desired mouse resolution, in dpi.
2260 psmouse.smartscroll=
2261 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2262 0 = disabled, 1 = enabled (default).
2264 pstore.backend= Specify the name of the pstore backend to use
2267 See Documentation/blockdev/paride.txt.
2270 [KNL] Number of legacy pty's. Overwrites compiled-in
2273 quiet [KNL] Disable most log messages
2278 See Documentation/md.txt.
2280 ramdisk_blocksize= [RAM]
2281 See Documentation/blockdev/ramdisk.txt.
2283 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2284 See Documentation/blockdev/ramdisk.txt.
2286 rcupdate.blimit= [KNL,BOOT]
2287 Set maximum number of finished RCU callbacks to process
2290 rcupdate.qhimark= [KNL,BOOT]
2291 Set threshold of queued
2292 RCU callbacks over which batch limiting is disabled.
2294 rcupdate.qlowmark= [KNL,BOOT]
2295 Set threshold of queued RCU callbacks below which
2296 batch limiting is re-enabled.
2300 Run specified binary instead of /init from the ramdisk,
2301 used for early userspace startup. See initrd.
2303 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2304 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2305 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2308 [KNL, SMP] Set scheduler's default relax_domain_level.
2309 See Documentation/cgroups/cpusets.txt.
2311 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2313 reservetop= [X86-32]
2315 Reserves a hole at the top of the kernel virtual
2320 Set the amount of memory to reserve for BIOS at
2321 the bottom of the address space.
2323 reset_devices [KNL] Force drivers to reset the underlying device
2324 during initialization.
2327 Specify the partition device for software suspend
2329 resume_offset= [SWSUSP]
2330 Specify the offset from the beginning of the partition
2331 given by "resume=" at which the swap header is located,
2332 in <PAGE_SIZE> units (needed only for swap files).
2333 See Documentation/power/swsusp-and-swap-files.txt
2335 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2336 read the resume files
2338 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2339 Useful for devices that are detected asynchronously
2340 (e.g. USB and MMC devices).
2342 hibernate= [HIBERNATION]
2343 noresume Don't check if there's a hibernation image
2344 present during boot.
2345 nocompress Don't compress/decompress hibernation images.
2347 retain_initrd [RAM] Keep initrd memory after extraction
2349 rhash_entries= [KNL,NET]
2350 Set number of hash buckets for route cache
2352 riscom8= [HW,SERIAL]
2353 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2355 ro [KNL] Mount root device read-only on boot
2357 root= [KNL] Root filesystem
2358 See name_to_dev_t comment in init/do_mounts.c.
2360 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2361 mount the root filesystem
2363 rootflags= [KNL] Set root filesystem mount option string
2365 rootfstype= [KNL] Set root filesystem type
2367 rootwait [KNL] Wait (indefinitely) for root device to show up.
2368 Useful for devices that are detected asynchronously
2369 (e.g. USB and MMC devices).
2371 rw [KNL] Mount root device read-write on boot
2373 S [KNL] Run init in single mode
2376 See drivers/net/irda/sa1100_ir.c.
2378 sbni= [NET] Granch SBNI12 leased line adapter
2380 sched_debug [KNL] Enables verbose scheduler debug messages.
2382 security= [SECURITY] Choose a security module to enable at boot.
2383 If this boot parameter is not specified, only the first
2384 security module asking for security registration will be
2385 loaded. An invalid security module name will be treated
2386 as if no module has been chosen.
2388 selinux= [SELINUX] Disable or enable SELinux at boot time.
2389 Format: { "0" | "1" }
2390 See security/selinux/Kconfig help text.
2393 Default value is set via kernel config option.
2394 If enabled at boot time, /selinux/disable can be used
2395 later to disable prior to initial policy load.
2397 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2398 Format: { "0" | "1" }
2399 See security/apparmor/Kconfig help text
2402 Default value is set via kernel config option.
2404 serialnumber [BUGS=X86-32]
2407 Maximal number of shapers.
2409 show_msr= [x86] show boot-time MSR settings
2410 Format: { <integer> }
2411 Show boot-time (BIOS-initialized) MSR settings.
2412 The parameter means the number of CPUs to show,
2413 for example 1 means boot CPU only.
2420 slub_debug[=options[,slabs]] [MM, SLUB]
2421 Enabling slub_debug allows one to determine the
2422 culprit if slab objects become corrupted. Enabling
2423 slub_debug can create guard zones around objects and
2424 may poison objects when not in use. Also tracks the
2425 last alloc / free. For more information see
2426 Documentation/vm/slub.txt.
2428 slub_max_order= [MM, SLUB]
2429 Determines the maximum allowed order for slabs.
2430 A high setting may cause OOMs due to memory
2431 fragmentation. For more information see
2432 Documentation/vm/slub.txt.
2434 slub_min_objects= [MM, SLUB]
2435 The minimum number of objects per slab. SLUB will
2436 increase the slab order up to slub_max_order to
2437 generate a sufficiently large slab able to contain
2438 the number of objects indicated. The higher the number
2439 of objects the smaller the overhead of tracking slabs
2440 and the less frequently locks need to be acquired.
2441 For more information see Documentation/vm/slub.txt.
2443 slub_min_order= [MM, SLUB]
2444 Determines the mininum page order for slabs. Must be
2445 lower than slub_max_order.
2446 For more information see Documentation/vm/slub.txt.
2448 slub_nomerge [MM, SLUB]
2449 Disable merging of slabs with similar size. May be
2450 necessary if there is some reason to distinguish
2451 allocs to different slabs. Debug options disable
2452 merging on their own.
2453 For more information see Documentation/vm/slub.txt.
2456 Format: <io1>[,<io2>[,...,<io8>]]
2458 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2459 attempt to substitute SMP alternatives once at boot.
2461 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2462 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2463 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2464 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2465 smsc-ircc2.ircc_irq= [HW] IRQ line
2466 smsc-ircc2.ircc_dma= [HW] DMA channel
2467 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2468 0: Toshiba Satellite 1800 (GP data pin select)
2469 1: Fast pin select (default)
2473 [KNL] Should the soft-lockup detector generate panics.
2476 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2477 See Documentation/laptops/sonypi.txt
2479 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2480 See Documentation/serial/specialix.txt.
2482 spia_io_base= [HW,MTD]
2488 Enabled the stack tracer on boot up.
2492 Set the STI (builtin display/keyboard on the HP-PARISC
2493 machines) console (graphic card) which should be used
2494 as the initial boot-console.
2495 See also comment in drivers/video/console/sticore.c.
2498 See comment in drivers/video/console/sticore.c.
2501 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2503 sunrpc.min_resvport=
2504 sunrpc.max_resvport=
2506 SunRPC servers often require that client requests
2507 originate from a privileged port (i.e. a port in the
2508 range 0 < portnr < 1024).
2509 An administrator who wishes to reserve some of these
2510 ports for other uses may adjust the range that the
2511 kernel's sunrpc client considers to be privileged
2512 using these two parameters to set the minimum and
2513 maximum port values.
2517 Control how the NFS server code allocates CPUs to
2518 service thread pools. Depending on how many NICs
2519 you have and where their interrupts are bound, this
2520 option will affect which CPUs will do NFS serving.
2521 Note: this parameter cannot be changed while the
2522 NFS server is running.
2524 auto the server chooses an appropriate mode
2525 automatically using heuristics
2526 global a single global pool contains all CPUs
2527 percpu one pool for each CPU
2528 pernode one pool for each NUMA node (equivalent
2529 to global on non-NUMA machines)
2531 sunrpc.tcp_slot_table_entries=
2532 sunrpc.udp_slot_table_entries=
2534 Sets the upper limit on the number of simultaneous
2535 RPC calls that can be sent from the client to a
2536 server. Increasing these values may allow you to
2537 improve throughput, but will also increase the
2538 amount of memory reserved for use by the client.
2541 [KNL] Enable accounting of swap in memory resource
2542 controller if no parameter or 1 is given or disable
2543 it if 0 is given (See Documentation/cgroups/memory.txt)
2545 swiotlb= [IA-64] Number of I/O TLB slabs
2549 sysfs.deprecated=0|1 [KNL]
2550 Enable/disable old style sysfs layout for old udev
2551 on older distributions. When this option is enabled
2552 very new udev will not work anymore. When this option
2553 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2554 in older udev will not work anymore.
2555 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2556 the kernel configuration.
2558 sysrq_always_enabled
2560 Ignore sysrq setting - this boot parameter will
2561 neutralize any effect of /proc/sys/kernel/sysrq.
2562 Useful for debugging.
2566 test_suspend= [SUSPEND]
2567 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2568 standby suspend) as the system sleep state to briefly
2569 enter during system startup. The system is woken from
2570 this state using a wakeup-capable RTC alarm.
2572 thash_entries= [KNL,NET]
2573 Set number of hash buckets for TCP connection
2575 thermal.act= [HW,ACPI]
2576 -1: disable all active trip points in all thermal zones
2577 <degrees C>: override all lowest active trip points
2579 thermal.crt= [HW,ACPI]
2580 -1: disable all critical trip points in all thermal zones
2581 <degrees C>: override all critical trip points
2583 thermal.nocrt= [HW,ACPI]
2584 Set to disable actions on ACPI thermal zone
2585 critical and hot trip points.
2587 thermal.off= [HW,ACPI]
2588 1: disable ACPI thermal control
2590 thermal.psv= [HW,ACPI]
2591 -1: disable all passive trip points
2592 <degrees C>: override all passive trip points to this
2595 thermal.tzp= [HW,ACPI]
2596 Specify global default ACPI thermal zone polling rate
2597 <deci-seconds>: poll all this frequency
2598 0: no polling (default)
2601 Force threading of all interrupt handlers except those
2602 marked explicitely IRQF_NO_THREAD.
2606 Specify if the kernel should make use of the cpu
2607 topology information if the hardware supports this.
2608 The scheduler will make use of this information and
2609 e.g. base its process migration decisions on it.
2614 tpm_suspend_pcr=[HW,TPM]
2615 Format: integer pcr id
2616 Specify that at suspend time, the tpm driver
2617 should extend the specified pcr with zeros,
2618 as a workaround for some chips which fail to
2619 flush the last written pcr on TPM_SaveState.
2620 This will guarantee that all the other pcrs
2623 trace_buf_size=nn[KMG]
2624 [FTRACE] will set tracing buffer size.
2626 trace_event=[event-list]
2627 [FTRACE] Set and start specified trace events in order
2628 to facilitate early boot debugging.
2629 See also Documentation/trace/events.txt
2631 tsc= Disable clocksource stability checks for TSC.
2633 [x86] reliable: mark tsc clocksource as reliable, this
2634 disables clocksource verification at runtime, as well
2635 as the stability checks done at bootup. Used to enable
2636 high-resolution timer mode on older hardware, and in
2637 virtualized environment.
2638 [x86] noirqtime: Do not use TSC to do irq accounting.
2639 Used to run time disable IRQ_TIME_ACCOUNTING on any
2640 platforms where RDTSC is slow and this accounting
2643 turbografx.map[2|3]= [HW,JOY]
2644 TurboGraFX parallel port interface
2646 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2647 See also Documentation/input/joystick-parport.txt
2649 udbg-immortal [PPC] When debugging early kernel crashes that
2650 happen after console_init() and before a proper
2651 console driver takes over, this boot options might
2652 help "seeing" what's going on.
2654 uhash_entries= [KNL,NET]
2655 Set number of hash buckets for UDP/UDP-Lite connections
2658 [USB] Ignore overcurrent events (default N).
2659 Some badly-designed motherboards generate lots of
2660 bogus events, for ports that aren't wired to
2661 anything. Set this parameter to avoid log spamming.
2662 Note that genuine overcurrent events won't be
2666 [X86] Cause panic on unknown NMI.
2668 usbcore.authorized_default=
2669 [USB] Default USB device authorization:
2670 (default -1 = authorized except for wireless USB,
2671 0 = not authorized, 1 = authorized)
2673 usbcore.autosuspend=
2674 [USB] The autosuspend time delay (in seconds) used
2675 for newly-detected USB devices (default 2). This
2676 is the time required before an idle device will be
2677 autosuspended. Devices for which the delay is set
2678 to a negative value won't be autosuspended at all.
2680 usbcore.usbfs_snoop=
2681 [USB] Set to log all usbfs traffic (default 0 = off).
2683 usbcore.blinkenlights=
2684 [USB] Set to cycle leds on hubs (default 0 = off).
2686 usbcore.old_scheme_first=
2687 [USB] Start with the old device initialization
2688 scheme (default 0 = off).
2690 usbcore.use_both_schemes=
2691 [USB] Try the other device initialization scheme
2692 if the first one fails (default 1 = enabled).
2694 usbcore.initial_descriptor_timeout=
2695 [USB] Specifies timeout for the initial 64-byte
2696 USB_REQ_GET_DESCRIPTOR request in milliseconds
2697 (default 5000 = 5.0 seconds).
2700 [USBHID] The interval which mice are to be polled at.
2702 usb-storage.delay_use=
2703 [UMS] The delay in seconds before a new device is
2704 scanned for Logical Units (default 5).
2707 [UMS] A list of quirks entries to supplement or
2708 override the built-in unusual_devs list. List
2709 entries are separated by commas. Each entry has
2710 the form VID:PID:Flags where VID and PID are Vendor
2711 and Product ID values (4-digit hex numbers) and
2712 Flags is a set of characters, each corresponding
2713 to a common usb-storage quirk flag as follows:
2714 a = SANE_SENSE (collect more than 18 bytes
2716 b = BAD_SENSE (don't collect more than 18
2717 bytes of sense data);
2718 c = FIX_CAPACITY (decrease the reported
2719 device capacity by one sector);
2720 d = NO_READ_DISC_INFO (don't use
2721 READ_DISC_INFO command);
2722 e = NO_READ_CAPACITY_16 (don't use
2723 READ_CAPACITY_16 command);
2724 h = CAPACITY_HEURISTICS (decrease the
2725 reported device capacity by one
2726 sector if the number is odd);
2727 i = IGNORE_DEVICE (don't bind to this
2729 l = NOT_LOCKABLE (don't try to lock and
2730 unlock ejectable media);
2731 m = MAX_SECTORS_64 (don't transfer more
2732 than 64 sectors = 32 KB at a time);
2733 n = INITIAL_READ10 (force a retry of the
2734 initial READ(10) command);
2735 o = CAPACITY_OK (accept the capacity
2736 reported by the device);
2737 r = IGNORE_RESIDUE (the device reports
2738 bogus residue values);
2739 s = SINGLE_LUN (the device has only one
2741 w = NO_WP_DETECT (don't test whether the
2742 medium is write-protected).
2743 Example: quirks=0419:aaf5:rl,0421:0433:rc
2745 user_debug= [KNL,ARM]
2747 See arch/arm/Kconfig.debug help text.
2748 1 - undefined instruction events
2750 4 - invalid data aborts
2753 Example: user_debug=31
2756 [X86] Flags controlling user PTE allocations.
2758 nohigh = do not allocate PTE pages in
2759 HIGHMEM regardless of setting
2763 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2764 vdso=1: enable VDSO (default)
2765 vdso=0: disable VDSO mapping
2768 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2769 vdso32=1: enable 32-bit VDSO (default)
2770 vdso32=0: disable 32-bit VDSO mapping
2773 vector=percpu: enable percpu vector domain
2775 video= [FB] Frame buffer configuration
2776 See Documentation/fb/modedb.txt.
2778 vga= [BOOT,X86-32] Select a particular video mode
2779 See Documentation/x86/boot.txt and
2780 Documentation/svga.txt.
2781 Use vga=ask for menu.
2782 This is actually a boot loader parameter; the value is
2783 passed to the kernel using a special protocol.
2785 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2786 size of <nn>. This can be used to increase the
2787 minimum size (128MB on x86). It can also be used to
2788 decrease the size and leave more room for directly
2791 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2794 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2797 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2801 Controls the behavior of vsyscalls (i.e. calls to
2802 fixed addresses of 0xffffffffff600x00 from legacy
2803 code). Most statically-linked binaries and older
2804 versions of glibc use these calls. Because these
2805 functions are at fixed addresses, they make nice
2806 targets for exploits that can control RIP.
2808 emulate Vsyscalls turn into traps and are emulated
2811 native [default] Vsyscalls are native syscall
2813 This is a little bit faster than trapping
2814 and makes a few dynamic recompilers work
2815 better than they would in emulation mode.
2816 It also makes exploits much easier to write.
2818 none Vsyscalls don't work at all. This makes
2819 them quite hard to use for exploits but
2820 might break your system.
2822 vt.cur_default= [VT] Default cursor shape.
2823 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2824 the parameters of the <Esc>[?A;B;Cc escape sequence;
2825 see VGA-softcursor.txt. Default: 2 = underline.
2827 vt.default_blu= [VT]
2828 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2829 Change the default blue palette of the console.
2830 This is a 16-member array composed of values
2833 vt.default_grn= [VT]
2834 Format: <green0>,<green1>,<green2>,...,<green15>
2835 Change the default green palette of the console.
2836 This is a 16-member array composed of values
2839 vt.default_red= [VT]
2840 Format: <red0>,<red1>,<red2>,...,<red15>
2841 Change the default red palette of the console.
2842 This is a 16-member array composed of values
2848 Set system-wide default UTF-8 mode for all tty's.
2849 Default is 1, i.e. UTF-8 mode is enabled for all
2850 newly opened terminals.
2852 vt.global_cursor_default=
2855 Set system-wide default for whether a cursor
2856 is shown on new VTs. Default is -1,
2857 i.e. cursors will be created by default unless
2858 overridden by individual drivers. 0 will hide
2859 cursors, 1 will display them.
2861 watchdog timers [HW,WDT] For information on watchdog timers,
2862 see Documentation/watchdog/watchdog-parameters.txt
2863 or other driver-specific files in the
2864 Documentation/watchdog/ directory.
2866 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2867 default x2apic cluster mode on platforms
2870 x86_mrst_timer= [X86-32,APBT]
2871 Choose timer option for x86 Moorestown MID platform.
2872 Two valid options are apbt timer only and lapic timer
2873 plus one apbt timer for broadcast timer.
2874 x86_mrst_timer=apbt_only | lapic_and_apbt
2876 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2877 xd_geo= See header of drivers/block/xd.c.
2879 xen_emul_unplug= [HW,X86,XEN]
2880 Unplug Xen emulated devices
2881 Format: [unplug0,][unplug1]
2882 ide-disks -- unplug primary master IDE devices
2883 aux-ide-disks -- unplug non-primary-master IDE devices
2884 nics -- unplug network devices
2885 all -- unplug all emulated devices (NICs and IDE disks)
2886 unnecessary -- unplugging emulated devices is
2887 unnecessary even if the host did not respond to
2889 never -- do not unplug even if version check succeeds
2891 xirc2ps_cs= [NET,PCMCIA]
2893 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2895 ______________________________________________________________________
2899 Add more DRM drivers.
git.openpandora.org / pandora-kernel.git / blob