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, s3_leds, 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 s3_leds is for debugging; it flashes the keyboard LEDs
262 3 times as soon as the kernel's real-mode entry point is
264 s4_nohwsig prevents ACPI hardware signature from being
265 used during resume from hibernation.
266 old_ordering causes the ACPI 1.0 ordering of the _PTS
267 control method, with respect to putting devices into
268 low power states, to be enforced (the ACPI 2.0 ordering
269 of _PTS is used by default).
270 nonvs prevents the kernel from saving/restoring the
271 ACPI NVS memory during suspend/hibernation and resume.
272 sci_force_enable causes the kernel to set SCI_EN directly
273 on resume from S1/S3 (which is against the ACPI spec,
274 but some broken systems don't work without it).
276 acpi_use_timer_override [HW,ACPI]
277 Use timer override. For some broken Nvidia NF5 boards
278 that require a timer override, but don't have HPET
280 acpi_enforce_resources= [ACPI]
281 { strict | lax | no }
282 Check for resource conflicts between native drivers
283 and ACPI OperationRegions (SystemIO and SystemMemory
284 only). IO ports and memory declared in ACPI might be
285 used by the ACPI subsystem in arbitrary AML code and
286 can interfere with legacy drivers.
287 strict (default): access to resources claimed by ACPI
288 is denied; legacy drivers trying to access reserved
289 resources will fail to bind to device using them.
290 lax: access to resources claimed by ACPI is allowed;
291 legacy drivers trying to access reserved resources
292 will bind successfully but a warning message is logged.
293 no: ACPI OperationRegions are not marked as reserved,
294 no further checks are performed.
296 add_efi_memmap [EFI; X86] Include EFI memory map in
297 kernel's map of available physical RAM.
300 { off | try_unsupported }
301 off: disable AGP support
302 try_unsupported: try to drive unsupported chipsets
303 (may crash computer or cause data corruption)
306 See Documentation/sound/alsa/alsa-parameters.txt
309 Allow the default userspace alignment fault handler
310 behaviour to be specified. Bit 0 enables warnings,
311 bit 1 enables fixups, and bit 2 sends a segfault.
313 align_va_addr= [X86-64]
314 Align virtual addresses by clearing slice [14:12] when
315 allocating a VMA at process creation time. This option
316 gives you up to 3% performance improvement on AMD F15h
317 machines (where it is enabled by default) for a
318 CPU-intensive style benchmark, and it can vary highly in
319 a microbenchmark depending on workload and compiler.
321 32: only for 32-bit processes
322 64: only for 64-bit processes
323 on: enable for both 32- and 64-bit processes
324 off: disable for both 32- and 64-bit processes
326 amd_iommu= [HW,X86-64]
327 Pass parameters to the AMD IOMMU driver in the system.
329 fullflush - enable flushing of IO/TLB entries when
330 they are unmapped. Otherwise they are
331 flushed before they will be reused, which
333 off - do not initialize any AMD IOMMU found in
336 amijoy.map= [HW,JOY] Amiga joystick support
337 Map of devices attached to JOY0DAT and JOY1DAT
339 See also Documentation/input/joystick.txt
341 analog.map= [HW,JOY] Analog joystick and gamepad support
342 Specifies type or capabilities of an analog joystick
343 connected to one of 16 gameports
344 Format: <type1>,<type2>,..<type16>
347 Power management functions (SPARCstation-4/5 + deriv.)
349 Disable APC CPU standby support. SPARCstation-Fox does
350 not play well with APC CPU idle - disable it if you have
351 APC and your system crashes randomly.
353 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
354 Change the output verbosity whilst booting
355 Format: { quiet (default) | verbose | debug }
356 Change the amount of debugging information output
357 when initialising the APIC and IO-APIC components.
360 See Documentation/networking/ipv6.txt.
362 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
363 Limit apic dumping. The parameter defines the maximal
364 number of local apics being dumped. Also it is possible
365 to set it to "all" by meaning -- no limit here.
366 Format: { 1 (default) | 2 | ... | all }.
367 The parameter valid if only apic=debug or
368 apic=verbose is specified.
369 Example: apic=debug show_lapic=all
371 apm= [APM] Advanced Power Management
372 See header of arch/x86/kernel/apm_32.c.
374 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
375 Format: <io>,<irq>,<nodeID>
379 atarimouse= [HW,MOUSE] Atari Mouse
381 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
382 EzKey and similar keyboards
384 atkbd.reset= [HW] Reset keyboard during initialization
386 atkbd.set= [HW] Select keyboard code set
387 Format: <int> (2 = AT (default), 3 = PS/2)
389 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
392 atkbd.softraw= [HW] Choose between synthetic and real raw mode
393 Format: <bool> (0 = real, 1 = synthetic (default))
395 atkbd.softrepeat= [HW]
396 Use software keyboard repeat
400 baycom_epp= [HW,AX25]
403 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
405 See header of drivers/net/hamradio/baycom_par.c.
407 baycom_ser_fdx= [HW,AX25]
408 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
409 Format: <io>,<irq>,<mode>[,<baud>]
410 See header of drivers/net/hamradio/baycom_ser_fdx.c.
412 baycom_ser_hdx= [HW,AX25]
413 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
414 Format: <io>,<irq>,<mode>
415 See header of drivers/net/hamradio/baycom_ser_hdx.c.
417 boot_delay= Milliseconds to delay each printk during boot.
418 Values larger than 10 seconds (10000) are changed to
422 bootmem_debug [KNL] Enable bootmem allocator debug messages.
424 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
425 bttv.radio= Most important insmod options are available as
427 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
430 bulk_remove=off [PPC] This parameter disables the use of the pSeries
431 firmware feature for flushing multiple hpte entries
434 c101= [NET] Moxa C101 synchronous serial card
436 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
437 Sometimes CPU hardware bugs make them report the cache
438 size incorrectly. The kernel will attempt work arounds
439 to fix known problems, but for some CPUs it is not
440 possible to determine what the correct size should be.
441 This option provides an override for these situations.
444 [SECURITY] Disable capabilities. This would normally
445 be used only if an alternative security model is to be
446 configured. Potentially dangerous and should only be
447 used if you are entirely sure of the consequences.
449 ccw_timeout_log [S390]
450 See Documentation/s390/CommonIO for details.
452 cgroup_disable= [KNL] Disable a particular controller
453 Format: {name of the controller(s) to disable}
454 {Currently supported controllers - "memory"}
456 checkreqprot [SELINUX] Set initial checkreqprot flag value.
457 Format: { "0" | "1" }
458 See security/selinux/Kconfig help text.
459 0 -- check protection applied by kernel (includes
460 any implied execute protection).
461 1 -- check protection requested by application.
462 Default value is set via a kernel config option.
463 Value can be changed at runtime via
464 /selinux/checkreqprot.
467 See Documentation/s390/CommonIO for details.
469 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
471 Forces specified clocksource (if available) to be used
472 when calculating gettimeofday(). If specified
473 clocksource is not available, it defaults to PIT.
474 Format: { pit | tsc | cyclone | pmtmr }
476 clocksource= Override the default clocksource
478 Override the default clocksource and use the clocksource
479 with the name specified.
480 Some clocksource names to choose from, depending on
482 [all] jiffies (this is the base, fallback clocksource)
484 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
485 pxa_timer,timer3,32k_counter,timer0_1
487 [X86-32] pit,hpet,tsc;
488 scx200_hrt on Geode; cyclone on IBM x440
496 clearcpuid=BITNUM [X86]
497 Disable CPUID feature X for the kernel. See
498 arch/x86/include/asm/cpufeature.h for the valid bit
499 numbers. Note the Linux specific bits are not necessarily
500 stable over kernel options, but the vendor specific
502 Also note that user programs calling CPUID directly
503 or using the feature without checking anything
504 will still see it. This just prevents it from
505 being used by the kernel or shown in /proc/cpuinfo.
506 Also note the kernel might malfunction if you disable
509 cmo_free_hint= [PPC] Format: { yes | no }
510 Specify whether pages are marked as being inactive
511 when they are freed. This is used in CMO environments
512 to determine OS memory pressure for page stealing by
516 code_bytes [X86] How many bytes of object code to print
521 com20020= [HW,NET] ARCnet - COM20020 chipset
523 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
525 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
529 ARCnet - COM90xx chipset (memory-mapped buffers)
530 Format: <io>[,<irq>[,<memstart>]]
532 condev= [HW,S390] console device
535 console= [KNL] Output console device and options.
537 tty<n> Use the virtual console device <n>.
541 Use the specified serial port. The options are of
542 the form "bbbbpnf", where "bbbb" is the baud rate,
543 "p" is parity ("n", "o", or "e"), "n" is number of
544 bits, and "f" is flow control ("r" for RTS or
545 omit it). Default is "9600n8".
547 See Documentation/serial-console.txt for more
549 Documentation/networking/netconsole.txt for an
552 uart[8250],io,<addr>[,options]
553 uart[8250],mmio,<addr>[,options]
554 Start an early, polled-mode console on the 8250/16550
555 UART at the specified I/O port or MMIO address,
556 switching to the matching ttyS device later. The
557 options are the same as for ttyS, above.
559 If the device connected to the port is not a TTY but a braille
560 device, prepend "brl," before the device type, for instance
562 For now, only VisioBraille is supported.
564 consoleblank= [KNL] The console blank (screen saver) timeout in
565 seconds. Defaults to 10*60 = 10mins. A value of 0
566 disables the blank timer.
569 [KNL] Change the default value for
570 /proc/<pid>/coredump_filter.
571 See also Documentation/filesystems/proc.txt.
573 cpuidle.off=1 [CPU_IDLE]
574 disable the cpuidle sub-system
576 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
578 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
580 crashkernel=size[KMG][@offset[KMG]]
581 [KNL] Using kexec, Linux can switch to a 'crash kernel'
582 upon panic. This parameter reserves the physical
583 memory region [offset, offset + size] for that kernel
584 image. If '@offset' is omitted, then a suitable offset
585 is selected automatically. Check
586 Documentation/kdump/kdump.txt for further details.
588 crashkernel=range1:size1[,range2:size2,...][@offset]
589 [KNL] Same as above, but depends on the memory
590 in the running system. The syntax of range is
591 start-[end] where start and end are both
592 a memory unit (amount[KMG]). See also
593 Documentation/kdump/kdump.txt for an example.
598 cs89x0_media= [HW,NET]
599 Format: { rj45 | aui | bnc }
602 See header of drivers/s390/block/dasd_devmap.c.
604 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
605 (one device per port)
606 Format: <port#>,<type>
607 See also Documentation/input/joystick-parport.txt
609 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
610 time. See Documentation/dynamic-debug-howto.txt for
613 debug [KNL] Enable kernel debugging (events log level).
616 [KNL] verbose self-tests
618 Print debugging info while doing the locking API
620 We default to 0 (no extra messages), setting it to
621 1 will print _a lot_ more information - normally
622 only useful to kernel developers.
624 debug_objects [KNL] Enable object debugging
627 [KNL] Disable object debugging
629 debugpat [X86] Enable PAT debugging
631 decnet.addr= [HW,NET]
632 Format: <area>[,<node>]
633 See also Documentation/networking/decnet.txt.
636 [same as hugepagesz=] The size of the default
637 HugeTLB page size. This is the size represented by
638 the legacy /proc/ hugepages APIs, used for SHM, and
639 default size when mounting hugetlbfs filesystems.
640 Defaults to the default architecture's huge page size
644 Set number of hash buckets for dentry cache.
647 IO parameters + enable/disable command.
649 digiepca= [HW,SERIAL]
650 See drivers/char/README.epca and
651 Documentation/serial/digiepca.txt.
654 See Documentation/networking/ipv6.txt.
656 disable_ddw [PPC/PSERIES]
657 Disable Dynamic DMA Window support. Use this if
658 to workaround buggy firmware.
661 See Documentation/networking/ipv6.txt.
663 disable_mtrr_cleanup [X86]
664 The kernel tries to adjust MTRR layout from continuous
665 to discrete, to make X server driver able to add WB
666 entry later. This parameter disables that.
668 disable_mtrr_trim [X86, Intel and AMD only]
669 By default the kernel will trim any uncacheable
670 memory out of your available memory pool based on
671 MTRR settings. This parameter disables that behavior,
672 possibly causing your machine to run very slowly.
674 disable_timer_pin_1 [X86]
675 Disable PIN 1 of APIC timer
676 Can be useful to work around chipset bugs.
678 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
679 this option disables the debugging code at boot.
681 dma_debug_entries=<number>
682 This option allows to tune the number of preallocated
683 entries for DMA-API debugging code. One entry is
684 required per DMA-API allocation. Use this if the
685 DMA-API debugging code disables itself because the
686 architectural default is too low.
688 dma_debug_driver=<driver_name>
689 With this option the DMA-API debugging driver
690 filter feature can be enabled at boot time. Just
691 pass the driver to filter for as the parameter.
692 The filter can be disabled or changed to another
693 driver later using sysfs.
695 drm_kms_helper.edid_firmware=[<connector>:]<file>
696 Broken monitors, graphic adapters and KVMs may
697 send no or incorrect EDID data sets. This parameter
698 allows to specify an EDID data set in the
699 /lib/firmware directory that is used instead.
700 Generic built-in EDID data sets are used, if one of
701 edid/1024x768.bin, edid/1280x1024.bin,
702 edid/1680x1050.bin, or edid/1920x1080.bin is given
703 and no file with the same name exists. Details and
704 instructions how to build your own EDID data are
705 available in Documentation/EDID/HOWTO.txt. An EDID
706 data set will only be used for a particular connector,
707 if its name and a colon are prepended to the EDID
712 earlycon= [KNL] Output early console device and options.
713 uart[8250],io,<addr>[,options]
714 uart[8250],mmio,<addr>[,options]
715 uart[8250],mmio32,<addr>[,options]
716 Start an early, polled-mode console on the 8250/16550
717 UART at the specified I/O port or MMIO address.
718 MMIO inter-register address stride is either 8-bit
719 (mmio) or 32-bit (mmio32).
720 The options are the same as for ttyS, above.
722 earlyprintk= [X86,SH,BLACKFIN]
724 earlyprintk=serial[,ttySn[,baudrate]]
725 earlyprintk=ttySn[,baudrate]
726 earlyprintk=dbgp[debugController#]
728 Append ",keep" to not disable it when the real console
731 Only vga or serial or usb debug port at a time.
733 Currently only ttyS0 and ttyS1 are supported.
735 Interaction with the standard serial driver is not
738 The VGA output is eventually overwritten by the real
741 ekgdboc= [X86,KGDB] Allow early kernel console debugging
744 This is designed to be used in conjunction with
745 the boot argument: earlyprintk=vga
748 Format: {"off" | "on" | "skip[mbr]"}
750 eisa_irq_edge= [PARISC,HW]
751 See header of drivers/parisc/eisa.c.
754 See comment before function elanfreq_setup() in
755 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
758 Format: {"cfq" | "deadline" | "noop"}
759 See Documentation/block/cfq-iosched.txt and
760 Documentation/block/deadline-iosched.txt for details.
762 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
763 Specifies physical address of start of kernel core
764 image elf header and optionally the size. Generally
765 kexec loader will pass this option to capture kernel.
766 See Documentation/kdump/kdump.txt for details.
768 enable_mtrr_cleanup [X86]
769 The kernel tries to adjust MTRR layout from continuous
770 to discrete, to make X server driver able to add WB
771 entry later. This parameter enables that.
773 enable_timer_pin_1 [X86]
774 Enable PIN 1 of APIC timer
775 Can be useful to work around chipset bugs
776 (in particular on some ATI chipsets).
777 The kernel tries to set a reasonable default.
779 enforcing [SELINUX] Set initial enforcing status.
781 See security/selinux/Kconfig help text.
782 0 -- permissive (log only, no denials).
783 1 -- enforcing (deny and log).
785 Value can be changed at runtime via /selinux/enforce.
788 Disable Error Record Serialization Table (ERST)
791 ether= [HW,NET] Ethernet cards parameters
792 This option is obsoleted by the "netdev=" option, which
793 has equivalent usage. See its documentation for details.
797 Permit 'security.evm' to be updated regardless of
798 current integrity status.
802 fail_make_request=[KNL]
803 General fault injection mechanism.
804 Format: <interval>,<probability>,<space>,<times>
805 See also Documentation/fault-injection/.
808 See Documentation/blockdev/floppy.txt.
810 force_pal_cache_flush
811 [IA-64] Avoid check_sal_cache_flush which may hang on
812 buggy SAL_CACHE_FLUSH implementations. Using this
813 parameter will force ia64_sal_cache_flush to call
814 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
817 [FTRACE] will set and start the specified tracer
818 as early as possible in order to facilitate early
821 ftrace_dump_on_oops[=orig_cpu]
822 [FTRACE] will dump the trace buffers on oops.
823 If no parameter is passed, ftrace will dump
824 buffers of all CPUs, but if you pass orig_cpu, it will
825 dump only the buffer of the CPU that triggered the
828 ftrace_filter=[function-list]
829 [FTRACE] Limit the functions traced by the function
830 tracer at boot up. function-list is a comma separated
831 list of functions. This list can be changed at run
832 time by the set_ftrace_filter file in the debugfs
835 ftrace_notrace=[function-list]
836 [FTRACE] Do not trace the functions specified in
837 function-list. This list can be changed at run time
838 by the set_ftrace_notrace file in the debugfs
841 ftrace_graph_filter=[function-list]
842 [FTRACE] Limit the top level callers functions traced
843 by the function graph tracer at boot up.
844 function-list is a comma separated list of functions
845 that can be changed at run time by the
846 set_graph_function file in the debugfs tracing directory.
849 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
850 support via parallel port (up to 5 devices per port)
851 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
852 See also Documentation/input/joystick-parport.txt
856 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
860 gcov_persist= [GCOV] When non-zero (default), profiling data for
861 kernel modules is saved and remains accessible via
862 debugfs, even when the module is unloaded/reloaded.
863 When zero, profiling data is discarded and associated
864 debugfs files are removed at module unload time.
866 gpt [EFI] Forces disk with valid GPT signature but
867 invalid Protective MBR to be treated as GPT.
869 hashdist= [KNL,NUMA] Large hashes allocated during boot
870 are distributed across NUMA nodes. Defaults on
871 for 64-bit NUMA, off otherwise.
872 Format: 0 | 1 (for off | on)
874 hcl= [IA-64] SGI's Hardware Graph compatibility layer
876 hd= [EIDE] (E)IDE hard drive subsystem geometry
877 Format: <cyl>,<head>,<sect>
880 Disable Hardware Error Source Table (HEST) support;
881 corresponding firmware-first mode error processing
882 logic will be disabled.
884 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
885 size of <nn>. This works even on boxes that have no
886 highmem otherwise. This also works to reduce highmem
887 size on bigger boxes.
889 highres= [KNL] Enable/disable high resolution timer mode.
890 Valid parameters: "on", "off"
894 See Documentation/isdn/README.HiSax.
898 hpet= [X86-32,HPET] option to control HPET usage
899 Format: { enable (default) | disable | force |
901 disable: disable HPET and use PIT instead
902 force: allow force enabled of undocumented chips (ICH4,
904 verbose: show contents of HPET registers during setup
906 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
907 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
908 On x86-64 and powerpc, this option can be specified
909 multiple times interleaved with hugepages= to reserve
910 huge pages of different sizes. Valid pages sizes on
911 x86-64 are 2M (when the CPU supports "pse") and 1G
912 (when the CPU supports the "pdpe1gb" cpuinfo flag)
913 Note that 1GB pages can only be allocated at boot time
914 using hugepages= and not freed afterwards.
916 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
917 terminal devices. Valid values: 0..8
918 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
919 If specified, z/VM IUCV HVC accepts connections
920 from listed z/VM user IDs only.
923 Do not unregister boot console at start. This is only
924 useful for debugging when something happens in the window
925 between unregistering the boot console and initializing
928 i2c_bus= [HW] Override the default board specific I2C bus speed
929 or register an additional I2C bus that is not
930 registered from board initialization code.
934 i8042.debug [HW] Toggle i8042 debug mode
935 i8042.direct [HW] Put keyboard port into non-translated mode
936 i8042.dumbkbd [HW] Pretend that controller can only read data from
937 keyboard and cannot control its state
938 (Don't attempt to blink the leds)
939 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
940 i8042.nokbd [HW] Don't check/create keyboard port
941 i8042.noloop [HW] Disable the AUX Loopback command while probing
943 i8042.nomux [HW] Don't check presence of an active multiplexing
945 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
947 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
948 i8042.reset [HW] Reset the controller during init and cleanup
949 i8042.unlock [HW] Unlock (ignore) the keylock
953 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
954 indicates that the driver is running on unsupported
956 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
957 does not match list of supported models.
959 [HW] Report power status in /proc/i8k
960 (disabled by default)
961 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
965 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
967 ide-core.nodma= [HW] (E)IDE subsystem
968 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
969 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
970 .cdrom .chs .ignore_cable are additional options
971 See Documentation/ide/ide.txt.
973 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
974 Claim all unknown PCI IDE storage controllers.
977 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
978 Poll forces a polling idle loop that can slightly
979 improve the performance of waking up a idle CPU, but
980 will use a lot of power and make the system run hot.
982 idle=mwait: On systems which support MONITOR/MWAIT but
983 the kernel chose to not use it because it doesn't save
984 as much power as a normal idle loop, use the
985 MONITOR/MWAIT idle loop anyways. Performance should be
986 the same as idle=poll.
987 idle=halt: Halt is forced to be used for CPU idle.
988 In such case C2/C3 won't be used again.
989 idle=nomwait: Disable mwait for CPU C-states
991 ignore_loglevel [KNL]
992 Ignore loglevel setting - this will print /all/
993 kernel messages to the console. Useful for debugging.
994 We also add it as printk module parameter, so users
995 could change it dynamically, usually by
996 /sys/module/printk/parameters/ignore_loglevel.
999 Set number of hash buckets for inode cache.
1002 Format: { "0" | "1" }
1003 0 -- integrity auditing messages. (Default)
1004 1 -- enable informational integrity auditing messages.
1007 Format: { "sha1" | "md5" }
1011 Load a policy which meets the needs of the Trusted
1012 Computing Base. This means IMA will measure all
1013 programs exec'd, files mmap'd for exec, and all files
1014 opened for read by uid=0.
1018 Run specified binary instead of /sbin/init as init
1021 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1022 for working out where the kernel is dying during
1025 initrd= [BOOT] Specify the location of the initial ramdisk
1027 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1030 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1032 Enable intel iommu driver.
1034 Disable intel iommu driver.
1035 igfx_off [Default Off]
1036 By default, gfx is mapped as normal device. If a gfx
1037 device has a dedicated DMAR unit, the DMAR unit is
1038 bypassed by not enabling DMAR with this option. In
1039 this case, gfx device will use physical address for
1042 With this option iommu will not optimize to look
1043 for io virtual address below 32-bit forcing dual
1044 address cycle on pci bus for cards supporting greater
1045 than 32-bit addressing. The default is to look
1046 for translation below 32-bit and if not available
1047 then look in the higher range.
1048 strict [Default Off]
1049 With this option on every unmap_single operation will
1050 result in a hardware IOTLB flush operation as opposed
1051 to batching them for performance.
1052 sp_off [Default Off]
1053 By default, super page will be supported if Intel IOMMU
1054 has the capability. With this option, super page will
1056 intremap= [X86-64, Intel-IOMMU]
1057 on enable Interrupt Remapping (default)
1058 off disable Interrupt Remapping
1059 nosid disable Source ID checking
1061 BIOS x2APIC opt-out request will be ignored
1065 iomem= Disable strict checking of access to MMIO memory
1066 strict regions from userspace.
1082 io7= [HW] IO7 for Marvel based alpha systems
1083 See comment before marvel_specify_io7 in
1084 arch/alpha/kernel/core_marvel.c.
1086 io_delay= [X86] I/O delay method
1088 Standard port 0x80 based delay
1090 Alternate port 0xed based delay (needed on some systems)
1092 Simple two microseconds delay
1097 See Documentation/filesystems/nfs/nfsroot.txt.
1099 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1100 See comment before ip2_setup() in
1101 drivers/char/ip2/ip2base.c.
1104 When an interrupt is not handled search all handlers
1105 for it. Intended to get systems with badly broken
1109 When an interrupt is not handled search all handlers
1110 for it. Also check all handlers each timer
1111 interrupt. Intended to get systems with badly broken
1115 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1117 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1119 <cpu number>,...,<cpu number>
1121 <cpu number>-<cpu number>
1122 (must be a positive range in ascending order)
1124 <cpu number>,...,<cpu number>-<cpu number>
1126 This option can be used to specify one or more CPUs
1127 to isolate from the general SMP balancing and scheduling
1128 algorithms. You can move a process onto or off an
1129 "isolated" CPU via the CPU affinity syscalls or cpuset.
1130 <cpu number> begins at 0 and the maximum value is
1131 "number of CPUs in system - 1".
1133 This option is the preferred way to isolate CPUs. The
1134 alternative -- manually setting the CPU mask of all
1135 tasks in the system -- can cause problems and
1136 suboptimal load balancer performance.
1140 js= [HW,JOY] Analog joystick
1141 See Documentation/input/joystick.txt.
1145 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1146 specifies the amount of memory usable by the kernel
1147 for non-movable allocations. The requested amount is
1148 spread evenly throughout all nodes in the system. The
1149 remaining memory in each node is used for Movable
1150 pages. In the event, a node is too small to have both
1151 kernelcore and Movable pages, kernelcore pages will
1152 take priority and other nodes will have a larger number
1153 of kernelcore pages. The Movable zone is used for the
1154 allocation of pages that may be reclaimed or moved
1155 by the page migration subsystem. This means that
1156 HugeTLB pages may not be allocated from this zone.
1157 Note that allocations like PTEs-from-HighMem still
1158 use the HighMem zone if it exists, and the Normal
1159 zone if it does not.
1161 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1162 Format: <Controller#>[,poll interval]
1163 The controller # is the number of the ehci usb debug
1164 port as it is probed via PCI. The poll interval is
1165 optional and is the number seconds in between
1166 each poll cycle to the debug port in case you need
1167 the functionality for interrupting the kernel with
1168 gdb or control-c on the dbgp connection. When
1169 not using this parameter you use sysrq-g to break into
1170 the kernel debugger.
1172 kgdboc= [KGDB,HW] kgdb over consoles.
1173 Requires a tty driver that supports console polling,
1174 or a supported polling keyboard driver (non-usb).
1175 Serial only format: <serial_device>[,baud]
1176 keyboard only format: kbd
1177 keyboard and serial format: kbd,<serial_device>[,baud]
1178 Optional Kernel mode setting:
1179 kms, kbd format: kms,kbd
1180 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1182 kgdbwait [KGDB] Stop kernel execution and enter the
1183 kernel debugger at the earliest opportunity.
1185 kmac= [MIPS] korina ethernet MAC address.
1186 Configure the RouterBoard 532 series on-chip
1187 Ethernet adapter MAC address.
1189 kmemleak= [KNL] Boot-time kmemleak enable/disable
1190 Valid arguments: on, off
1193 kstack=N [X86] Print N words from the kernel stack
1196 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1197 Default is 0 (don't ignore, but inject #GP)
1199 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1200 Default is 1 (enabled)
1202 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1206 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1207 Default is 1 (enabled)
1209 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1211 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1213 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1214 (virtualized MMU) support on capable Intel chips.
1215 Default is 1 (enabled)
1217 kvm-intel.emulate_invalid_guest_state=
1218 [KVM,Intel] Enable emulation of invalid guest states
1219 Default is 0 (disabled)
1221 kvm-intel.flexpriority=
1222 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1223 Default is 1 (enabled)
1226 [KVM,Intel] Enable VMX nesting (nVMX).
1227 Default is 0 (disabled)
1229 kvm-intel.unrestricted_guest=
1230 [KVM,Intel] Disable unrestricted guest feature
1231 (virtualized real and unpaged mode) on capable
1232 Intel chips. Default is 1 (enabled)
1234 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1235 feature (tagged TLBs) on capable Intel chips.
1236 Default is 1 (enabled)
1242 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1245 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1248 libata.dma= [LIBATA] DMA control
1249 libata.dma=0 Disable all PATA and SATA DMA
1250 libata.dma=1 PATA and SATA Disk DMA only
1251 libata.dma=2 ATAPI (CDROM) DMA only
1252 libata.dma=4 Compact Flash DMA only
1253 Combinations also work, so libata.dma=3 enables DMA
1254 for disks and CDROMs, but not CFs.
1256 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1257 libata.ignore_hpa=0 keep BIOS limits (default)
1258 libata.ignore_hpa=1 ignore limits, using full disk
1260 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1264 libata.force= [LIBATA] Force configurations. The format is comma
1265 separated list of "[ID:]VAL" where ID is
1266 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1267 matching port, link or device. Basically, it matches
1268 the ATA ID string printed on console by libata. If
1269 the whole ID part is omitted, the last PORT and DEVICE
1270 values are used. If ID hasn't been specified yet, the
1271 configuration applies to all ports, links and devices.
1273 If only DEVICE is omitted, the parameter applies to
1274 the port and all links and devices behind it. DEVICE
1275 number of 0 either selects the first device or the
1276 first fan-out link behind PMP device. It does not
1277 select the host link. DEVICE number of 15 selects the
1278 host link and device attached to it.
1280 The VAL specifies the configuration to force. As long
1281 as there's no ambiguity shortcut notation is allowed.
1282 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1283 The following configurations can be forced.
1285 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1286 Any ID with matching PORT is used.
1288 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1290 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1291 udma[/][16,25,33,44,66,100,133] notation is also
1294 * [no]ncq: Turn on or off NCQ.
1296 * nohrst, nosrst, norst: suppress hard, soft
1299 * dump_id: dump IDENTIFY data.
1301 If there are multiple matching configurations changing
1302 the same attribute, the last one is used.
1304 memblock=debug [KNL] Enable memblock debug messages.
1306 load_ramdisk= [RAM] List of ramdisks to load from floppy
1307 See Documentation/blockdev/ramdisk.txt.
1309 lockd.nlm_grace_period=P [NFS] Assign grace period.
1312 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1315 lockd.nlm_timeout=T [NFS] Assign timeout value.
1318 lockd.nlm_udpport=M [NFS] Assign UDP port.
1321 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1324 loglevel= All Kernel Messages with a loglevel smaller than the
1325 console loglevel will be printed to the console. It can
1326 also be changed with klogd or other programs. The
1327 loglevels are defined as follows:
1329 0 (KERN_EMERG) system is unusable
1330 1 (KERN_ALERT) action must be taken immediately
1331 2 (KERN_CRIT) critical conditions
1332 3 (KERN_ERR) error conditions
1333 4 (KERN_WARNING) warning conditions
1334 5 (KERN_NOTICE) normal but significant condition
1335 6 (KERN_INFO) informational
1336 7 (KERN_DEBUG) debug-level messages
1338 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1339 in bytes. n must be a power of two. The default
1340 size is set in the kernel config file.
1342 logo.nologo [FB] Disables display of the built-in Linux logo.
1343 This may be used to provide more screen space for
1344 kernel log messages and is useful when debugging
1345 kernel boot problems.
1347 lp=0 [LP] Specify parallel ports to use, e.g,
1348 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1349 lp=reset first parallel port). 'lp=0' disables the
1350 lp=auto printer driver. 'lp=reset' (which can be
1351 specified in addition to the ports) causes
1352 attached printers to be reset. Using
1353 lp=port1,port2,... specifies the parallel ports
1354 to associate lp devices with, starting with
1355 lp0. A port specification may be 'none' to skip
1356 that lp device, or a parport name such as
1357 'parport0'. Specifying 'lp=auto' instead of a
1358 port specification list means that device IDs
1359 from each port should be examined, to see if
1360 an IEEE 1284-compliant printer is attached; if
1361 so, the driver will manage that printer.
1362 See also header of drivers/char/lp.c.
1365 Sets loops_per_jiffy to given constant, thus avoiding
1366 time-consuming boot-time autodetection (up to 250 ms per
1367 CPU). 0 enables autodetection (default). To determine
1368 the correct value for your kernel, boot with normal
1369 autodetection and see what value is printed. Note that
1370 on SMP systems the preset will be applied to all CPUs,
1371 which is likely to cause problems if your CPUs need
1372 significantly divergent settings. An incorrect value
1373 will cause delays in the kernel to be wrong, leading to
1374 unpredictable I/O errors and other breakage. Although
1375 unlikely, in the extreme case this might damage your
1379 Format: <io>,<irq>,<dma>
1381 machvec= [IA-64] Force the use of a particular machine-vector
1382 (machvec) in a generic kernel.
1383 Example: machvec=hpzx1_swiotlb
1385 machtype= [Loongson] Share the same kernel image file between different
1387 Example: machtype=lemote-yeeloong-2f-7inch
1389 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1390 than or equal to this physical address is ignored.
1392 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1393 should make use of. maxcpus=n : n >= 0 limits the
1394 kernel to using 'n' processors. n=0 is a special case,
1395 it is equivalent to "nosmp", which also disables
1398 max_loop= [LOOP] The number of loop block devices that get
1399 (loop.max_loop) unconditionally pre-created at init time. The default
1400 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1401 of statically allocating a predefined number, loop
1402 devices can be requested on-demand with the
1403 /dev/loop-control interface.
1407 mce [X86-32] Machine Check Exception
1409 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1411 md= [HW] RAID subsystems devices and level
1412 See Documentation/md.txt.
1415 Format: <first>,<last>
1416 Specifies range of consoles to be captured by the MDA.
1418 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1419 Amount of memory to be used when the kernel is not able
1420 to see the whole system memory or for test.
1421 [X86-32] Use together with memmap= to avoid physical
1422 address space collisions. Without memmap= PCI devices
1423 could be placed at addresses belonging to unused RAM.
1425 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1429 [KNL,SH] Allow user to override the default size for
1430 per-device physically contiguous DMA buffers.
1432 memmap=exactmap [KNL,X86] Enable setting of an exact
1433 E820 memory map, as specified by the user.
1434 Such memmap=exactmap lines can be constructed based on
1435 BIOS output or other requirements. See the memmap=nn@ss
1438 memmap=nn[KMG]@ss[KMG]
1439 [KNL] Force usage of a specific region of memory
1440 Region of memory to be used, from ss to ss+nn.
1442 memmap=nn[KMG]#ss[KMG]
1443 [KNL,ACPI] Mark specific memory as ACPI data.
1444 Region of memory to be used, from ss to ss+nn.
1446 memmap=nn[KMG]$ss[KMG]
1447 [KNL,ACPI] Mark specific memory as reserved.
1448 Region of memory to be used, from ss to ss+nn.
1449 Example: Exclude memory from 0x18690000-0x1869ffff
1450 memmap=64K$0x18690000
1452 memmap=0x10000$0x18690000
1454 memory_corruption_check=0/1 [X86]
1455 Some BIOSes seem to corrupt the first 64k of
1456 memory when doing things like suspend/resume.
1457 Setting this option will scan the memory
1458 looking for corruption. Enabling this will
1459 both detect corruption and prevent the kernel
1460 from using the memory being corrupted.
1461 However, its intended as a diagnostic tool; if
1462 repeatable BIOS-originated corruption always
1463 affects the same memory, you can use memmap=
1464 to prevent the kernel from using that memory.
1466 memory_corruption_check_size=size [X86]
1467 By default it checks for corruption in the low
1468 64k, making this memory unavailable for normal
1469 use. Use this parameter to scan for
1470 corruption in more or less memory.
1472 memory_corruption_check_period=seconds [X86]
1473 By default it checks for corruption every 60
1474 seconds. Use this parameter to check at some
1475 other rate. 0 disables periodic checking.
1477 memtest= [KNL,X86] Enable memtest
1479 default : 0 <disable>
1480 Specifies the number of memtest passes to be
1481 performed. Each pass selects another test
1482 pattern from a given set of patterns. Memtest
1483 fills the memory with this pattern, validates
1484 memory contents and reserves bad memory
1485 regions that are detected.
1487 meye.*= [HW] Set MotionEye Camera parameters
1488 See Documentation/video4linux/meye.txt.
1490 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1491 Multi-Function General Purpose Timers on AMD Geode
1494 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1495 the BIOS has incorrectly applied a workaround. TinyBIOS
1496 version 0.98 is known to be affected, 0.99 fixes the
1497 problem by letting the user disable the workaround.
1501 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1502 physical address is ignored.
1504 mini2440= [ARM,HW,KNL]
1505 Format:[0..2][b][c][t]
1507 MINI2440 configuration specification:
1508 0 - The attached screen is the 3.5" TFT
1509 1 - The attached screen is the 7" TFT
1510 2 - The VGA Shield is attached (1024x768)
1511 Leaving out the screen size parameter will not load
1512 the TFT driver, and the framebuffer will be left
1514 b - Enable backlight. The TFT backlight pin will be
1515 linked to the kernel VESA blanking code and a GPIO
1516 LED. This parameter is not necessary when using the
1518 c - Enable the s3c camera interface.
1519 t - Reserved for enabling touchscreen support. The
1520 touchscreen support is not enabled in the mainstream
1521 kernel as of 2.6.30, a preliminary port can be found
1522 in the "bleeding edge" mini2440 support kernel at
1523 http://repo.or.cz/w/linux-2.6/mini2440.git
1526 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1527 parameter allows control of the logging verbosity for
1528 the additional memory initialisation checks. A value
1529 of 0 disables mminit logging and a level of 4 will
1530 log everything. Information is printed at KERN_DEBUG
1531 so loglevel=8 may also need to be specified.
1534 [MOUSE] Maximum time between finger touching and
1535 leaving touchpad surface for touch to be considered
1536 a tap and be reported as a left button click (for
1537 touchpads working in absolute mode only).
1539 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1540 reporting absolute coordinates, such as tablets
1541 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1542 reporting absolute coordinates, such as tablets
1544 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1545 is similar to kernelcore except it specifies the
1546 amount of memory used for migratable allocations.
1547 If both kernelcore and movablecore is specified,
1548 then kernelcore will be at *least* the specified
1549 value but may be more. If movablecore on its own
1550 is specified, the administrator must be careful
1551 that the amount of memory usable for all allocations
1554 MTD_Partition= [MTD]
1555 Format: <name>,<region-number>,<size>,<offset>
1557 MTD_Region= [MTD] Format:
1558 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1561 See drivers/mtd/cmdlinepart.c.
1563 multitce=off [PPC] This parameter disables the use of the pSeries
1564 firmware feature for updating multiple TCE entries
1567 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1569 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1571 boundary - index of last SLC block on Flex-OneNAND.
1572 The remaining blocks are configured as MLC blocks.
1573 lock - Configure if Flex-OneNAND boundary should be locked.
1574 Once locked, the boundary cannot be changed.
1575 1 indicates lock status, 0 indicates unlock status.
1578 ARM/S3C2412 JIVE boot control
1580 See arch/arm/mach-s3c2412/mach-jive.c
1582 mtouchusb.raw_coordinates=
1583 [HW] Make the MicroTouch USB driver use raw coordinates
1584 ('y', default) or cooked coordinates ('n')
1586 mtrr_chunk_size=nn[KMG] [X86]
1587 used for mtrr cleanup. It is largest continuous chunk
1588 that could hold holes aka. UC entries.
1590 mtrr_gran_size=nn[KMG] [X86]
1591 Used for mtrr cleanup. It is granularity of mtrr block.
1593 Large value could prevent small alignment from
1596 mtrr_spare_reg_nr=n [X86]
1598 Range: 0,7 : spare reg number
1600 Used for mtrr cleanup. It is spare mtrr entries number.
1601 Set to 2 or more if your graphical card needs more.
1603 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1605 netdev= [NET] Network devices parameters
1606 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1607 Note that mem_start is often overloaded to mean
1608 something different and driver-specific.
1609 This usage is only documented in each driver source
1613 [NETFILTER] Enable connection tracking flow accounting
1614 0 to disable accounting
1615 1 to enable accounting
1618 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1619 See Documentation/filesystems/nfs/nfsroot.txt.
1621 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1622 See Documentation/filesystems/nfs/nfsroot.txt.
1624 nfsrootdebug [NFS] enable nfsroot debugging messages.
1625 See Documentation/filesystems/nfs/nfsroot.txt.
1627 nfs.callback_tcpport=
1628 [NFS] set the TCP port on which the NFSv4 callback
1629 channel should listen.
1632 [NFS] sets the pathname to the program which is used
1633 to update the NFS client cache entries.
1635 nfs.cache_getent_timeout=
1636 [NFS] sets the timeout after which an attempt to
1637 update a cache entry is deemed to have failed.
1639 nfs.idmap_cache_timeout=
1640 [NFS] set the maximum lifetime for idmapper cache
1644 [NFS] enable 64-bit inode numbers.
1645 If zero, the NFS client will fake up a 32-bit inode
1646 number for the readdir() and stat() syscalls instead
1647 of returning the full 64-bit number.
1648 The default is to return 64-bit inode numbers.
1650 nfs.nfs4_disable_idmapping=
1651 [NFSv4] When set, this option disables the NFSv4
1652 idmapper on the client, but only if the mount
1653 is using the 'sec=sys' security flavour. This may
1654 make migration from legacy NFSv2/v3 systems easier
1655 provided that the server has the appropriate support.
1656 The default is to always enable NFSv4 idmapping.
1658 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1659 when a NMI is triggered.
1660 Format: [state][,regs][,debounce][,die]
1662 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1663 Format: [panic,][nopanic,][num]
1665 0 - turn nmi_watchdog off
1666 When panic is specified, panic when an NMI watchdog
1667 timeout occurs (or 'nopanic' to override the opposite
1669 This is useful when you use a panic=... timeout and
1670 need the box quickly up again.
1672 netpoll.carrier_timeout=
1673 [NET] Specifies amount of time (in seconds) that
1674 netpoll should wait for a carrier. By default netpoll
1677 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1678 emulation library even if a 387 maths coprocessor
1682 [HW] Never suspend the console
1683 Disable suspending of consoles during suspend and
1684 hibernate operations. Once disabled, debugging
1685 messages can reach various consoles while the rest
1686 of the system is being put to sleep (ie, while
1687 debugging driver suspend/resume hooks). This may
1688 not work reliably with all consoles, but is known
1689 to work with serial and VGA consoles.
1690 To facilitate more flexible debugging, we also add
1691 console_suspend, a printk module parameter to control
1692 it. Users could use console_suspend (usually
1693 /sys/module/printk/parameters/console_suspend) to
1694 turn on/off it dynamically.
1696 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1697 caches in the slab allocator. Saves per-node memory,
1698 but will impact performance.
1702 noapic [SMP,APIC] Tells the kernel to not make use of any
1703 IOAPICs that may be present in the system.
1705 noautogroup Disable scheduler automatic task group creation.
1707 nobats [PPC] Do not use BATs for mapping kernel lowmem
1708 on "Classic" PPC cores.
1712 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1714 nodelayacct [KNL] Disable per-task delay accounting
1716 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1718 nodsp [SH] Disable hardware DSP at boot time.
1720 noefi [X86] Disable EFI runtime services support.
1725 On X86-32 available only on PAE configured kernels.
1726 noexec=on: enable non-executable mappings (default)
1727 noexec=off: disable non-executable mappings
1730 Disable SMEP (Supervisor Mode Execution Protection)
1731 even if it is supported by processor.
1734 This affects only 32-bit executables.
1735 noexec32=on: enable non-executable mappings (default)
1736 read doesn't imply executable mappings
1737 noexec32=off: disable non-executable mappings
1738 read implies executable mappings
1740 nofpu [SH] Disable hardware FPU at boot time.
1742 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1743 register save and restore. The kernel will only save
1744 legacy floating-point registers on task switch.
1746 noxsave [BUGS=X86] Disables x86 extended register state save
1747 and restore using xsave. The kernel will fallback to
1748 enabling legacy floating-point and sse state.
1750 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1751 wfi(ARM) instruction doesn't work correctly and not to
1752 use it. This is also useful when using JTAG debugger.
1754 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1755 instruction doesn't work correctly and not to
1758 no_file_caps Tells the kernel not to honor file capabilities. The
1759 only way then for a file to be executed with privilege
1760 is to be setuid root or executed by root.
1762 nohalt [IA-64] Tells the kernel not to use the power saving
1763 function PAL_HALT_LIGHT when idle. This increases
1764 power-consumption. On the positive side, it reduces
1765 interrupt wake-up latency, which may improve performance
1766 in certain environments such as networked servers or
1769 nohz= [KNL] Boottime enable/disable dynamic ticks
1770 Valid arguments: on, off
1773 noiotrap [SH] Disables trapped I/O port accesses.
1775 noirqdebug [X86-32] Disables the code which attempts to detect and
1776 disable unhandled interrupt sources.
1778 no_timer_check [X86,APIC] Disables the code which tests for
1779 broken timer IRQ sources.
1781 noisapnp [ISAPNP] Disables ISA PnP code.
1783 noinitrd [RAM] Tells the kernel not to load any configured
1786 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1788 [Deprecated - use intremap=off]
1792 nojitter [IA-64] Disables jitter checking for ITC timers.
1794 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1796 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1799 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1800 steal time is computed, but won't influence scheduler
1803 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1805 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1807 noltlbs [PPC] Do not use large page/tlb entries for kernel
1808 lowmem mapping on PPC40x.
1810 nomca [IA-64] Disable machine check abort handling
1812 nomce [X86-32] Machine Check Exception
1814 nomfgpt [X86-32] Disable Multi-Function General Purpose
1815 Timer usage (for AMD Geode machines).
1817 nopat [X86] Disable PAT (page attribute table extension of
1818 pagetables) support.
1820 norandmaps Don't use address space randomization. Equivalent to
1821 echo 0 > /proc/sys/kernel/randomize_va_space
1823 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1825 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1826 with UP alternatives
1828 noresidual [PPC] Don't use residual data on PReP machines.
1830 nordrand [X86] Disable the direct use of the RDRAND
1831 instruction even if it is supported by the
1832 processor. RDRAND is still available to user
1835 noresume [SWSUSP] Disables resume and restores original swap
1838 no-scroll [VGA] Disables scrollback.
1839 This is required for the Braillex ib80-piezo Braille
1840 reader made by F.H. Papenmeier (Germany).
1844 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1846 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1847 and disable the IO APIC. legacy for "maxcpus=0".
1849 nosoftlockup [KNL] Disable the soft-lockup detector.
1851 nosync [HW,M68K] Disables sync negotiation for all devices.
1853 notsc [BUGS=X86-32] Disable Time Stamp Counter
1855 nousb [USB] Disable the USB subsystem
1857 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1861 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1863 nptcg= [IA-64] Override max number of concurrent global TLB
1864 purges which is reported from either PAL_VM_SUMMARY or
1867 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1868 could support. nr_cpus=n : n >= 1 limits the kernel to
1869 supporting 'n' processors. Later in runtime you can not
1870 use hotplug cpu feature to put more cpu back to online.
1871 just like you compile the kernel NR_CPUS=n
1873 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1875 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1876 one of ['zone', 'node', 'default'] can be specified
1877 This can be set from sysctl after boot.
1878 See Documentation/sysctl/vm.txt for details.
1880 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1881 See Documentation/debugging-via-ohci1394.txt for more
1884 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1885 Rather than timing out after 20 ms if an EC
1886 command is not properly ACKed, override the length
1887 of the timeout. We have interrupts disabled while
1888 waiting for the ACK, so if this is set too high
1889 interrupts *may* be lost!
1891 omap_mux= [OMAP] Override bootloader pin multiplexing.
1892 Format: <mux_mode0.mode_name=value>...
1893 For example, to override I2C bus2:
1894 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1896 oprofile.timer= [HW]
1897 Use timer interrupt instead of performance counters
1899 oprofile.cpu_type= Force an oprofile cpu type
1900 This might be useful if you have an older oprofile
1901 userland or if you want common events.
1902 Format: { arch_perfmon }
1903 arch_perfmon: [X86] Force use of architectural
1904 perfmon on Intel CPUs instead of the
1905 CPU specific event set.
1907 oops=panic Always panic on oopses. Default is to just kill the
1908 process, but there is a small probability of
1909 deadlocking the machine.
1910 This will also cause panics on machine check exceptions.
1911 Useful together with panic=30 to trigger a reboot.
1914 See Documentation/sound/oss/oss-parameters.txt
1916 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1917 timeout > 0: seconds before rebooting
1918 timeout = 0: wait forever
1919 timeout < 0: reboot immediately
1922 parkbd.port= [HW] Parallel port number the keyboard adapter is
1923 connected to, default is 0.
1925 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1926 0 for XT, 1 for AT (default is AT).
1929 parport= [HW,PPT] Specify parallel ports. 0 disables.
1930 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1931 Use 'auto' to force the driver to use any
1932 IRQ/DMA settings detected (the default is to
1933 ignore detected IRQ/DMA settings because of
1934 possible conflicts). You can specify the base
1935 address, IRQ, and DMA settings; IRQ and DMA
1936 should be numbers, or 'auto' (for using detected
1937 settings on that particular port), or 'nofifo'
1938 (to avoid using a FIFO even if it is detected).
1939 Parallel ports are assigned in the order they
1940 are specified on the command line, starting
1943 parport_init_mode= [HW,PPT]
1944 Configure VIA parallel port to operate in
1945 a specific mode. This is necessary on Pegasos
1946 computer where firmware has no options for setting
1947 up parallel port mode and sets it to spp.
1948 Currently this function knows 686a and 8231 chips.
1949 Format: [spp|ps2|epp|ecp|ecpepp]
1952 Halt all CPUs after the first oops has been printed for
1953 the specified number of seconds. This is to be used if
1954 your oopses keep scrolling off the screen.
1959 See header of drivers/block/paride/pcd.c.
1960 See also Documentation/blockdev/paride.txt.
1962 pci=option[,option...] [PCI] various PCI subsystem options:
1963 earlydump [X86] dump PCI config space before the kernel
1965 off [X86] don't probe for the PCI bus
1966 bios [X86-32] force use of PCI BIOS, don't access
1967 the hardware directly. Use this if your machine
1968 has a non-standard PCI host bridge.
1969 nobios [X86-32] disallow use of PCI BIOS, only direct
1970 hardware access methods are allowed. Use this
1971 if you experience crashes upon bootup and you
1972 suspect they are caused by the BIOS.
1973 conf1 [X86] Force use of PCI Configuration
1975 conf2 [X86] Force use of PCI Configuration
1977 noaer [PCIE] If the PCIEAER kernel config parameter is
1978 enabled, this kernel boot option can be used to
1979 disable the use of PCIE advanced error reporting.
1980 nodomains [PCI] Disable support for multiple PCI
1981 root domains (aka PCI segments, in ACPI-speak).
1982 nommconf [X86] Disable use of MMCONFIG for PCI
1984 check_enable_amd_mmconf [X86] check for and enable
1985 properly configured MMIO access to PCI
1986 config space on AMD family 10h CPU
1987 nomsi [MSI] If the PCI_MSI kernel config parameter is
1988 enabled, this kernel boot option can be used to
1989 disable the use of MSI interrupts system-wide.
1990 noioapicquirk [APIC] Disable all boot interrupt quirks.
1991 Safety option to keep boot IRQs enabled. This
1992 should never be necessary.
1993 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1994 primary IO-APIC for bridges that cannot disable
1995 boot IRQs. This fixes a source of spurious IRQs
1996 when the system masks IRQs.
1997 noioapicreroute [APIC] Disable workaround that uses the
1998 boot IRQ equivalent of an IRQ that connects to
1999 a chipset where boot IRQs cannot be disabled.
2000 The opposite of ioapicreroute.
2001 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2002 routing table. These calls are known to be buggy
2003 on several machines and they hang the machine
2004 when used, but on other computers it's the only
2005 way to get the interrupt routing table. Try
2006 this option if the kernel is unable to allocate
2007 IRQs or discover secondary PCI buses on your
2009 rom [X86] Assign address space to expansion ROMs.
2010 Use with caution as certain devices share
2011 address decoders between ROMs and other
2013 norom [X86] Do not assign address space to
2014 expansion ROMs that do not already have
2015 BIOS assigned address ranges.
2016 nobar [X86] Do not assign address space to the
2017 BARs that weren't assigned by the BIOS.
2018 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2019 assigned automatically to PCI devices. You can
2020 make the kernel exclude IRQs of your ISA cards
2022 pirqaddr=0xAAAAA [X86] Specify the physical address
2023 of the PIRQ table (normally generated
2024 by the BIOS) if it is outside the
2025 F0000h-100000h range.
2026 lastbus=N [X86] Scan all buses thru bus #N. Can be
2027 useful if the kernel is unable to find your
2028 secondary buses and you want to tell it
2029 explicitly which ones they are.
2030 assign-busses [X86] Always assign all PCI bus
2031 numbers ourselves, overriding
2032 whatever the firmware may have done.
2033 usepirqmask [X86] Honor the possible IRQ mask stored
2034 in the BIOS $PIR table. This is needed on
2035 some systems with broken BIOSes, notably
2036 some HP Pavilion N5400 and Omnibook XE3
2037 notebooks. This will have no effect if ACPI
2038 IRQ routing is enabled.
2039 noacpi [X86] Do not use ACPI for IRQ routing
2040 or for PCI scanning.
2041 use_crs [X86] Use PCI host bridge window information
2042 from ACPI. On BIOSes from 2008 or later, this
2043 is enabled by default. If you need to use this,
2044 please report a bug.
2045 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2046 If you need to use this, please report a bug.
2047 routeirq Do IRQ routing for all PCI devices.
2048 This is normally done in pci_enable_device(),
2049 so this option is a temporary workaround
2050 for broken drivers that don't call it.
2051 skip_isa_align [X86] do not align io start addr, so can
2052 handle more pci cards
2053 firmware [ARM] Do not re-enumerate the bus but instead
2054 just use the configuration from the
2055 bootloader. This is currently used on
2056 IXP2000 systems where the bus has to be
2057 configured a certain way for adjunct CPUs.
2058 noearly [X86] Don't do any early type 1 scanning.
2059 This might help on some broken boards which
2060 machine check when some devices' config space
2061 is read. But various workarounds are disabled
2062 and some IOMMU drivers will not work.
2063 bfsort Sort PCI devices into breadth-first order.
2064 This sorting is done to get a device
2065 order compatible with older (<= 2.4) kernels.
2066 nobfsort Don't sort PCI devices into breadth-first order.
2067 cbiosize=nn[KMG] The fixed amount of bus space which is
2068 reserved for the CardBus bridge's IO window.
2069 The default value is 256 bytes.
2070 cbmemsize=nn[KMG] The fixed amount of bus space which is
2071 reserved for the CardBus bridge's memory
2072 window. The default value is 64 megabytes.
2075 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2076 Specifies alignment and device to reassign
2077 aligned memory resources.
2078 If <order of align> is not specified,
2079 PAGE_SIZE is used as alignment.
2080 PCI-PCI bridge can be specified, if resource
2081 windows need to be expanded.
2082 ecrc= Enable/disable PCIe ECRC (transaction layer
2083 end-to-end CRC checking).
2084 bios: Use BIOS/firmware settings. This is the
2088 realloc reallocate PCI resources if allocations done by BIOS
2091 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2094 force Enable ASPM even on devices that claim not to support it.
2095 WARNING: Forcing ASPM on may cause system lockups.
2097 pcie_ports= [PCIE] PCIe ports handling:
2098 auto Ask the BIOS whether or not to use native PCIe services
2099 associated with PCIe ports (PME, hot-plug, AER). Use
2100 them only if that is allowed by the BIOS.
2101 native Use native PCIe services associated with PCIe ports
2103 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2106 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2107 nomsi Do not use MSI for native PCIe PME signaling (this makes
2108 all PCIe root ports use INTx for all services).
2110 pcmv= [HW,PCMCIA] BadgePAD 4
2113 See Documentation/blockdev/paride.txt.
2115 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2118 See arch/parisc/kernel/pdc_chassis.c
2120 percpu_alloc= Select which percpu first chunk allocator to use.
2121 Currently supported values are "embed" and "page".
2122 Archs may support subset or none of the selections.
2123 See comments in mm/percpu.c for details on each
2124 allocator. This parameter is primarily for debugging
2125 and performance comparison.
2128 See Documentation/blockdev/paride.txt.
2131 See Documentation/blockdev/paride.txt.
2133 pirq= [SMP,APIC] Manual mp-table setup
2134 See Documentation/x86/i386/IO-APIC.txt.
2136 plip= [PPT,NET] Parallel port network link
2137 Format: { parport<nr> | timid | 0 }
2138 See also Documentation/parport.txt.
2140 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2141 Override pmtimer IOPort with a hex value.
2145 Enable PNP debug messages (depends on the
2146 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2147 via /sys/module/pnp/parameters/debug. We always show
2148 current resource usage; turning this on also shows
2149 possible settings and some assignment information.
2155 { on | off | curr | res | no-curr | no-res }
2158 [ISAPNP] Exclude IRQs for the autoconfiguration
2161 [ISAPNP] Exclude DMAs for the autoconfiguration
2163 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2164 Ranges are in pairs (I/O port base and size).
2167 [ISAPNP] Exclude memory regions for the
2169 Ranges are in pairs (memory base and size).
2171 ports= [IP_VS_FTP] IPVS ftp helper module
2173 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2175 Format: <port>,<port>....
2177 print-fatal-signals=
2178 [KNL] debug: print fatal signals
2180 If enabled, warn about various signal handling
2181 related application anomalies: too many signals,
2182 too many POSIX.1 timers, fatal signals causing a
2185 If you hit the warning due to signal overflow,
2186 you might want to try "ulimit -i unlimited".
2190 printk.always_kmsg_dump=
2191 Trigger kmsg_dump for cases other than kernel oops or
2193 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2196 printk.time= Show timing data prefixed to each printk message line
2197 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2199 processor.max_cstate= [HW,ACPI]
2200 Limit processor to maximum C-state
2201 max_cstate=9 overrides any DMI blacklist limit.
2203 processor.nocst [HW,ACPI]
2204 Ignore the _CST method to determine C-states,
2205 instead using the legacy FADT method
2207 profile= [KNL] Enable kernel profiling via /proc/profile
2208 Format: [schedule,]<number>
2209 Param: "schedule" - profile schedule points.
2210 Param: <number> - step/bucket size as a power of 2 for
2211 statistical time based profiling.
2212 Param: "sleep" - profile D-state sleeping (millisecs).
2213 Requires CONFIG_SCHEDSTATS
2214 Param: "kvm" - profile VM exits.
2216 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2218 See Documentation/blockdev/ramdisk.txt.
2220 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2221 probe for; one of (bare|imps|exps|lifebook|any).
2222 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2224 psmouse.resetafter= [HW,MOUSE]
2225 Try to reset the device after so many bad packets
2228 [HW,MOUSE] Set desired mouse resolution, in dpi.
2229 psmouse.smartscroll=
2230 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2231 0 = disabled, 1 = enabled (default).
2233 pstore.backend= Specify the name of the pstore backend to use
2236 See Documentation/blockdev/paride.txt.
2239 [KNL] Number of legacy pty's. Overwrites compiled-in
2242 quiet [KNL] Disable most log messages
2247 See Documentation/md.txt.
2249 ramdisk_blocksize= [RAM]
2250 See Documentation/blockdev/ramdisk.txt.
2252 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2253 See Documentation/blockdev/ramdisk.txt.
2255 rcupdate.blimit= [KNL,BOOT]
2256 Set maximum number of finished RCU callbacks to process
2259 rcupdate.qhimark= [KNL,BOOT]
2260 Set threshold of queued
2261 RCU callbacks over which batch limiting is disabled.
2263 rcupdate.qlowmark= [KNL,BOOT]
2264 Set threshold of queued RCU callbacks below which
2265 batch limiting is re-enabled.
2269 Run specified binary instead of /init from the ramdisk,
2270 used for early userspace startup. See initrd.
2272 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2273 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2274 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2277 [KNL, SMP] Set scheduler's default relax_domain_level.
2278 See Documentation/cgroups/cpusets.txt.
2280 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2282 reservetop= [X86-32]
2284 Reserves a hole at the top of the kernel virtual
2289 Set the amount of memory to reserve for BIOS at
2290 the bottom of the address space.
2292 reset_devices [KNL] Force drivers to reset the underlying device
2293 during initialization.
2296 Specify the partition device for software suspend
2298 resume_offset= [SWSUSP]
2299 Specify the offset from the beginning of the partition
2300 given by "resume=" at which the swap header is located,
2301 in <PAGE_SIZE> units (needed only for swap files).
2302 See Documentation/power/swsusp-and-swap-files.txt
2304 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2305 read the resume files
2307 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2308 Useful for devices that are detected asynchronously
2309 (e.g. USB and MMC devices).
2311 hibernate= [HIBERNATION]
2312 noresume Don't check if there's a hibernation image
2313 present during boot.
2314 nocompress Don't compress/decompress hibernation images.
2316 retain_initrd [RAM] Keep initrd memory after extraction
2318 rhash_entries= [KNL,NET]
2319 Set number of hash buckets for route cache
2321 riscom8= [HW,SERIAL]
2322 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2324 ro [KNL] Mount root device read-only on boot
2326 root= [KNL] Root filesystem
2327 See name_to_dev_t comment in init/do_mounts.c.
2329 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2330 mount the root filesystem
2332 rootflags= [KNL] Set root filesystem mount option string
2334 rootfstype= [KNL] Set root filesystem type
2336 rootwait [KNL] Wait (indefinitely) for root device to show up.
2337 Useful for devices that are detected asynchronously
2338 (e.g. USB and MMC devices).
2340 rw [KNL] Mount root device read-write on boot
2342 S [KNL] Run init in single mode
2345 See drivers/net/irda/sa1100_ir.c.
2347 sbni= [NET] Granch SBNI12 leased line adapter
2349 sched_debug [KNL] Enables verbose scheduler debug messages.
2351 security= [SECURITY] Choose a security module to enable at boot.
2352 If this boot parameter is not specified, only the first
2353 security module asking for security registration will be
2354 loaded. An invalid security module name will be treated
2355 as if no module has been chosen.
2357 selinux= [SELINUX] Disable or enable SELinux at boot time.
2358 Format: { "0" | "1" }
2359 See security/selinux/Kconfig help text.
2362 Default value is set via kernel config option.
2363 If enabled at boot time, /selinux/disable can be used
2364 later to disable prior to initial policy load.
2366 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2367 Format: { "0" | "1" }
2368 See security/apparmor/Kconfig help text
2371 Default value is set via kernel config option.
2373 serialnumber [BUGS=X86-32]
2376 Maximal number of shapers.
2378 show_msr= [x86] show boot-time MSR settings
2379 Format: { <integer> }
2380 Show boot-time (BIOS-initialized) MSR settings.
2381 The parameter means the number of CPUs to show,
2382 for example 1 means boot CPU only.
2389 slub_debug[=options[,slabs]] [MM, SLUB]
2390 Enabling slub_debug allows one to determine the
2391 culprit if slab objects become corrupted. Enabling
2392 slub_debug can create guard zones around objects and
2393 may poison objects when not in use. Also tracks the
2394 last alloc / free. For more information see
2395 Documentation/vm/slub.txt.
2397 slub_max_order= [MM, SLUB]
2398 Determines the maximum allowed order for slabs.
2399 A high setting may cause OOMs due to memory
2400 fragmentation. For more information see
2401 Documentation/vm/slub.txt.
2403 slub_min_objects= [MM, SLUB]
2404 The minimum number of objects per slab. SLUB will
2405 increase the slab order up to slub_max_order to
2406 generate a sufficiently large slab able to contain
2407 the number of objects indicated. The higher the number
2408 of objects the smaller the overhead of tracking slabs
2409 and the less frequently locks need to be acquired.
2410 For more information see Documentation/vm/slub.txt.
2412 slub_min_order= [MM, SLUB]
2413 Determines the mininum page order for slabs. Must be
2414 lower than slub_max_order.
2415 For more information see Documentation/vm/slub.txt.
2417 slub_nomerge [MM, SLUB]
2418 Disable merging of slabs with similar size. May be
2419 necessary if there is some reason to distinguish
2420 allocs to different slabs. Debug options disable
2421 merging on their own.
2422 For more information see Documentation/vm/slub.txt.
2425 Format: <io1>[,<io2>[,...,<io8>]]
2427 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2428 attempt to substitute SMP alternatives once at boot.
2430 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2431 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2432 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2433 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2434 smsc-ircc2.ircc_irq= [HW] IRQ line
2435 smsc-ircc2.ircc_dma= [HW] DMA channel
2436 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2437 0: Toshiba Satellite 1800 (GP data pin select)
2438 1: Fast pin select (default)
2442 [KNL] Should the soft-lockup detector generate panics.
2445 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2446 See Documentation/laptops/sonypi.txt
2448 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2449 See Documentation/serial/specialix.txt.
2451 spia_io_base= [HW,MTD]
2457 Enabled the stack tracer on boot up.
2461 Set the STI (builtin display/keyboard on the HP-PARISC
2462 machines) console (graphic card) which should be used
2463 as the initial boot-console.
2464 See also comment in drivers/video/console/sticore.c.
2467 See comment in drivers/video/console/sticore.c.
2470 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2472 sunrpc.min_resvport=
2473 sunrpc.max_resvport=
2475 SunRPC servers often require that client requests
2476 originate from a privileged port (i.e. a port in the
2477 range 0 < portnr < 1024).
2478 An administrator who wishes to reserve some of these
2479 ports for other uses may adjust the range that the
2480 kernel's sunrpc client considers to be privileged
2481 using these two parameters to set the minimum and
2482 maximum port values.
2486 Control how the NFS server code allocates CPUs to
2487 service thread pools. Depending on how many NICs
2488 you have and where their interrupts are bound, this
2489 option will affect which CPUs will do NFS serving.
2490 Note: this parameter cannot be changed while the
2491 NFS server is running.
2493 auto the server chooses an appropriate mode
2494 automatically using heuristics
2495 global a single global pool contains all CPUs
2496 percpu one pool for each CPU
2497 pernode one pool for each NUMA node (equivalent
2498 to global on non-NUMA machines)
2500 sunrpc.tcp_slot_table_entries=
2501 sunrpc.udp_slot_table_entries=
2503 Sets the upper limit on the number of simultaneous
2504 RPC calls that can be sent from the client to a
2505 server. Increasing these values may allow you to
2506 improve throughput, but will also increase the
2507 amount of memory reserved for use by the client.
2510 [KNL] Enable accounting of swap in memory resource
2511 controller if no parameter or 1 is given or disable
2512 it if 0 is given (See Documentation/cgroups/memory.txt)
2514 swiotlb= [IA-64] Number of I/O TLB slabs
2518 sysfs.deprecated=0|1 [KNL]
2519 Enable/disable old style sysfs layout for old udev
2520 on older distributions. When this option is enabled
2521 very new udev will not work anymore. When this option
2522 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2523 in older udev will not work anymore.
2524 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2525 the kernel configuration.
2527 sysrq_always_enabled
2529 Ignore sysrq setting - this boot parameter will
2530 neutralize any effect of /proc/sys/kernel/sysrq.
2531 Useful for debugging.
2535 test_suspend= [SUSPEND]
2536 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2537 standby suspend) as the system sleep state to briefly
2538 enter during system startup. The system is woken from
2539 this state using a wakeup-capable RTC alarm.
2541 thash_entries= [KNL,NET]
2542 Set number of hash buckets for TCP connection
2544 thermal.act= [HW,ACPI]
2545 -1: disable all active trip points in all thermal zones
2546 <degrees C>: override all lowest active trip points
2548 thermal.crt= [HW,ACPI]
2549 -1: disable all critical trip points in all thermal zones
2550 <degrees C>: override all critical trip points
2552 thermal.nocrt= [HW,ACPI]
2553 Set to disable actions on ACPI thermal zone
2554 critical and hot trip points.
2556 thermal.off= [HW,ACPI]
2557 1: disable ACPI thermal control
2559 thermal.psv= [HW,ACPI]
2560 -1: disable all passive trip points
2561 <degrees C>: override all passive trip points to this
2564 thermal.tzp= [HW,ACPI]
2565 Specify global default ACPI thermal zone polling rate
2566 <deci-seconds>: poll all this frequency
2567 0: no polling (default)
2570 Force threading of all interrupt handlers except those
2571 marked explicitely IRQF_NO_THREAD.
2575 Specify if the kernel should make use of the cpu
2576 topology information if the hardware supports this.
2577 The scheduler will make use of this information and
2578 e.g. base its process migration decisions on it.
2583 tpm_suspend_pcr=[HW,TPM]
2584 Format: integer pcr id
2585 Specify that at suspend time, the tpm driver
2586 should extend the specified pcr with zeros,
2587 as a workaround for some chips which fail to
2588 flush the last written pcr on TPM_SaveState.
2589 This will guarantee that all the other pcrs
2592 trace_buf_size=nn[KMG]
2593 [FTRACE] will set tracing buffer size.
2595 trace_event=[event-list]
2596 [FTRACE] Set and start specified trace events in order
2597 to facilitate early boot debugging.
2598 See also Documentation/trace/events.txt
2600 tsc= Disable clocksource stability checks for TSC.
2602 [x86] reliable: mark tsc clocksource as reliable, this
2603 disables clocksource verification at runtime, as well
2604 as the stability checks done at bootup. Used to enable
2605 high-resolution timer mode on older hardware, and in
2606 virtualized environment.
2607 [x86] noirqtime: Do not use TSC to do irq accounting.
2608 Used to run time disable IRQ_TIME_ACCOUNTING on any
2609 platforms where RDTSC is slow and this accounting
2612 turbografx.map[2|3]= [HW,JOY]
2613 TurboGraFX parallel port interface
2615 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2616 See also Documentation/input/joystick-parport.txt
2618 udbg-immortal [PPC] When debugging early kernel crashes that
2619 happen after console_init() and before a proper
2620 console driver takes over, this boot options might
2621 help "seeing" what's going on.
2623 uhash_entries= [KNL,NET]
2624 Set number of hash buckets for UDP/UDP-Lite connections
2627 [USB] Ignore overcurrent events (default N).
2628 Some badly-designed motherboards generate lots of
2629 bogus events, for ports that aren't wired to
2630 anything. Set this parameter to avoid log spamming.
2631 Note that genuine overcurrent events won't be
2635 [X86] Cause panic on unknown NMI.
2637 usbcore.authorized_default=
2638 [USB] Default USB device authorization:
2639 (default -1 = authorized except for wireless USB,
2640 0 = not authorized, 1 = authorized)
2642 usbcore.autosuspend=
2643 [USB] The autosuspend time delay (in seconds) used
2644 for newly-detected USB devices (default 2). This
2645 is the time required before an idle device will be
2646 autosuspended. Devices for which the delay is set
2647 to a negative value won't be autosuspended at all.
2649 usbcore.usbfs_snoop=
2650 [USB] Set to log all usbfs traffic (default 0 = off).
2652 usbcore.blinkenlights=
2653 [USB] Set to cycle leds on hubs (default 0 = off).
2655 usbcore.old_scheme_first=
2656 [USB] Start with the old device initialization
2657 scheme (default 0 = off).
2659 usbcore.use_both_schemes=
2660 [USB] Try the other device initialization scheme
2661 if the first one fails (default 1 = enabled).
2663 usbcore.initial_descriptor_timeout=
2664 [USB] Specifies timeout for the initial 64-byte
2665 USB_REQ_GET_DESCRIPTOR request in milliseconds
2666 (default 5000 = 5.0 seconds).
2669 [USBHID] The interval which mice are to be polled at.
2671 usb-storage.delay_use=
2672 [UMS] The delay in seconds before a new device is
2673 scanned for Logical Units (default 5).
2676 [UMS] A list of quirks entries to supplement or
2677 override the built-in unusual_devs list. List
2678 entries are separated by commas. Each entry has
2679 the form VID:PID:Flags where VID and PID are Vendor
2680 and Product ID values (4-digit hex numbers) and
2681 Flags is a set of characters, each corresponding
2682 to a common usb-storage quirk flag as follows:
2683 a = SANE_SENSE (collect more than 18 bytes
2685 b = BAD_SENSE (don't collect more than 18
2686 bytes of sense data);
2687 c = FIX_CAPACITY (decrease the reported
2688 device capacity by one sector);
2689 d = NO_READ_DISC_INFO (don't use
2690 READ_DISC_INFO command);
2691 e = NO_READ_CAPACITY_16 (don't use
2692 READ_CAPACITY_16 command);
2693 h = CAPACITY_HEURISTICS (decrease the
2694 reported device capacity by one
2695 sector if the number is odd);
2696 i = IGNORE_DEVICE (don't bind to this
2698 l = NOT_LOCKABLE (don't try to lock and
2699 unlock ejectable media);
2700 m = MAX_SECTORS_64 (don't transfer more
2701 than 64 sectors = 32 KB at a time);
2702 n = INITIAL_READ10 (force a retry of the
2703 initial READ(10) command);
2704 o = CAPACITY_OK (accept the capacity
2705 reported by the device);
2706 r = IGNORE_RESIDUE (the device reports
2707 bogus residue values);
2708 s = SINGLE_LUN (the device has only one
2710 w = NO_WP_DETECT (don't test whether the
2711 medium is write-protected).
2712 Example: quirks=0419:aaf5:rl,0421:0433:rc
2714 user_debug= [KNL,ARM]
2716 See arch/arm/Kconfig.debug help text.
2717 1 - undefined instruction events
2719 4 - invalid data aborts
2722 Example: user_debug=31
2725 [X86] Flags controlling user PTE allocations.
2727 nohigh = do not allocate PTE pages in
2728 HIGHMEM regardless of setting
2732 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2733 vdso=1: enable VDSO (default)
2734 vdso=0: disable VDSO mapping
2737 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2738 vdso32=1: enable 32-bit VDSO (default)
2739 vdso32=0: disable 32-bit VDSO mapping
2742 vector=percpu: enable percpu vector domain
2744 video= [FB] Frame buffer configuration
2745 See Documentation/fb/modedb.txt.
2747 vga= [BOOT,X86-32] Select a particular video mode
2748 See Documentation/x86/boot.txt and
2749 Documentation/svga.txt.
2750 Use vga=ask for menu.
2751 This is actually a boot loader parameter; the value is
2752 passed to the kernel using a special protocol.
2754 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2755 size of <nn>. This can be used to increase the
2756 minimum size (128MB on x86). It can also be used to
2757 decrease the size and leave more room for directly
2760 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2763 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2766 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2770 Controls the behavior of vsyscalls (i.e. calls to
2771 fixed addresses of 0xffffffffff600x00 from legacy
2772 code). Most statically-linked binaries and older
2773 versions of glibc use these calls. Because these
2774 functions are at fixed addresses, they make nice
2775 targets for exploits that can control RIP.
2777 emulate Vsyscalls turn into traps and are emulated
2780 native [default] Vsyscalls are native syscall
2782 This is a little bit faster than trapping
2783 and makes a few dynamic recompilers work
2784 better than they would in emulation mode.
2785 It also makes exploits much easier to write.
2787 none Vsyscalls don't work at all. This makes
2788 them quite hard to use for exploits but
2789 might break your system.
2791 vt.cur_default= [VT] Default cursor shape.
2792 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2793 the parameters of the <Esc>[?A;B;Cc escape sequence;
2794 see VGA-softcursor.txt. Default: 2 = underline.
2796 vt.default_blu= [VT]
2797 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2798 Change the default blue palette of the console.
2799 This is a 16-member array composed of values
2802 vt.default_grn= [VT]
2803 Format: <green0>,<green1>,<green2>,...,<green15>
2804 Change the default green palette of the console.
2805 This is a 16-member array composed of values
2808 vt.default_red= [VT]
2809 Format: <red0>,<red1>,<red2>,...,<red15>
2810 Change the default red palette of the console.
2811 This is a 16-member array composed of values
2817 Set system-wide default UTF-8 mode for all tty's.
2818 Default is 1, i.e. UTF-8 mode is enabled for all
2819 newly opened terminals.
2821 vt.global_cursor_default=
2824 Set system-wide default for whether a cursor
2825 is shown on new VTs. Default is -1,
2826 i.e. cursors will be created by default unless
2827 overridden by individual drivers. 0 will hide
2828 cursors, 1 will display them.
2830 watchdog timers [HW,WDT] For information on watchdog timers,
2831 see Documentation/watchdog/watchdog-parameters.txt
2832 or other driver-specific files in the
2833 Documentation/watchdog/ directory.
2835 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2836 default x2apic cluster mode on platforms
2839 x86_mrst_timer= [X86-32,APBT]
2840 Choose timer option for x86 Moorestown MID platform.
2841 Two valid options are apbt timer only and lapic timer
2842 plus one apbt timer for broadcast timer.
2843 x86_mrst_timer=apbt_only | lapic_and_apbt
2845 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2846 xd_geo= See header of drivers/block/xd.c.
2848 xen_emul_unplug= [HW,X86,XEN]
2849 Unplug Xen emulated devices
2850 Format: [unplug0,][unplug1]
2851 ide-disks -- unplug primary master IDE devices
2852 aux-ide-disks -- unplug non-primary-master IDE devices
2853 nics -- unplug network devices
2854 all -- unplug all emulated devices (NICs and IDE disks)
2855 unnecessary -- unplugging emulated devices is
2856 unnecessary even if the host did not respond to
2858 never -- do not unplug even if version check succeeds
2860 xirc2ps_cs= [NET,PCMCIA]
2862 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2864 ______________________________________________________________________
2868 Add more DRM drivers.
projects / linux-flexiantxendom0.git / blob