4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 ARM ARM architecture is enabled.
44 AVR32 AVR32 architecture is enabled.
45 AX25 Appropriate AX.25 support is enabled.
46 BLACKFIN Blackfin architecture is enabled.
47 DRM Direct Rendering Management support is enabled.
48 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
49 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
50 EFI EFI Partitioning (GPT) is enabled
51 EIDE EIDE/ATAPI support is enabled.
52 EVM Extended Verification Module
53 FB The frame buffer device is enabled.
54 FTRACE Function tracing enabled.
55 GCOV GCOV profiling is enabled.
56 HW Appropriate hardware is enabled.
57 IA-64 IA-64 architecture is enabled.
58 IMA Integrity measurement architecture is enabled.
59 IOSCHED More than one I/O scheduler is enabled.
60 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
61 IPV6 IPv6 support is enabled.
62 ISAPNP ISA PnP code is enabled.
63 ISDN Appropriate ISDN support is enabled.
64 JOY Appropriate joystick support is enabled.
65 KGDB Kernel debugger support is enabled.
66 KVM Kernel Virtual Machine support is enabled.
67 LIBATA Libata driver is enabled
68 LP Printer support is enabled.
69 LOOP Loopback device support is enabled.
70 M68k M68k architecture is enabled.
71 These options have more detailed description inside of
72 Documentation/m68k/kernel-options.txt.
73 MCA MCA bus support is enabled.
74 MDA MDA console support is enabled.
75 MIPS MIPS architecture is enabled.
76 MOUSE Appropriate mouse support is enabled.
77 MSI Message Signaled Interrupts (PCI).
78 MTD MTD (Memory Technology Device) support is enabled.
79 NET Appropriate network support is enabled.
80 NUMA NUMA support is enabled.
81 NFS Appropriate NFS support is enabled.
82 OSS OSS sound support is enabled.
83 PV_OPS A paravirtualized kernel is enabled.
84 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
85 PARISC The PA-RISC architecture is enabled.
86 PCI PCI bus support is enabled.
87 PCIE PCI Express support is enabled.
88 PCMCIA The PCMCIA subsystem is enabled.
89 PNP Plug & Play support is enabled.
90 PPC PowerPC architecture is enabled.
91 PPT Parallel port support is enabled.
92 PS2 Appropriate PS/2 support is enabled.
93 RAM RAM disk support is enabled.
94 S390 S390 architecture is enabled.
95 SCSI Appropriate SCSI support is enabled.
96 A lot of drivers have their options described inside
97 the Documentation/scsi/ sub-directory.
98 SECURITY Different security models are enabled.
99 SELINUX SELinux support is enabled.
100 APPARMOR AppArmor support is enabled.
101 SERIAL Serial support is enabled.
102 SH SuperH architecture is enabled.
103 SMP The kernel is an SMP kernel.
104 SPARC Sparc architecture is enabled.
105 SWSUSP Software suspend (hibernation) is enabled.
106 SUSPEND System suspend states are enabled.
107 TPM TPM drivers are enabled.
108 TS Appropriate touchscreen support is enabled.
109 UMS USB Mass Storage support is enabled.
110 USB USB support is enabled.
111 USBHID USB Human Interface Device support is enabled.
112 V4L Video For Linux support is enabled.
113 VGA The VGA console has been enabled.
114 VT Virtual terminal support is enabled.
115 WDT Watchdog support is enabled.
116 XT IBM PC/XT MFM hard disk support is enabled.
117 X86-32 X86-32, aka i386 architecture is enabled.
118 X86-64 X86-64 architecture is enabled.
119 More X86-64 boot options can be found in
120 Documentation/x86/x86_64/boot-options.txt .
121 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
122 XEN Xen support is enabled
124 In addition, the following text indicates that the option:
126 BUGS= Relates to possible processor bugs on the said processor.
127 KNL Is a kernel start-up parameter.
128 BOOT Is a boot loader parameter.
130 Parameters denoted with BOOT are actually interpreted by the boot
131 loader, and have no meaning to the kernel directly.
132 Do not modify the syntax of boot loader parameters without extreme
133 need or coordination with <Documentation/x86/boot.txt>.
135 There are also arch-specific kernel-parameters not documented here.
136 See for example <Documentation/x86/x86_64/boot-options.txt>.
138 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139 a trailing = on the name of any parameter states that that parameter will
140 be entered as an environment variable, whereas its absence indicates that
141 it will appear as a kernel argument readable via /proc/cmdline by programs
142 running once the system is up.
144 The number of kernel parameters is not limited, but the length of the
145 complete command line (parameters including spaces etc.) is limited to
146 a fixed number of characters. This limit depends on the architecture
147 and is between 256 and 4096 characters. It is defined in the file
148 ./include/asm/setup.h as COMMAND_LINE_SIZE.
150 Finally, the [KMG] suffix is commonly described after a number of kernel
151 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153 bytes respectively. Such letter suffixes can also be entirely omitted.
157 Advanced Configuration and Power Interface
158 Format: { force | off | strict | noirq | rsdt }
159 force -- enable ACPI if default was off
160 off -- disable ACPI if default was on
161 noirq -- do not use ACPI for IRQ routing
162 strict -- Be less tolerant of platforms that are not
163 strictly ACPI specification compliant.
164 rsdt -- prefer RSDT over (default) XSDT
165 copy_dsdt -- copy DSDT to memory
167 See also Documentation/power/runtime_pm.txt, pci=noacpi
169 acpi_rsdp= [ACPI,EFI,KEXEC]
170 Pass the RSDP address to the kernel, mostly used
171 on machines running EFI runtime service to boot the
172 second kernel for kdump.
174 acpi_apic_instance= [ACPI, IOAPIC]
176 2: use 2nd APIC table, if available
177 1,0: use 1st APIC table
180 acpi_backlight= [HW,ACPI]
181 acpi_backlight=vendor
183 If set to vendor, prefer vendor specific driver
184 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
185 of the ACPI video.ko driver.
187 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
188 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
190 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191 debug output. Bits in debug_layer correspond to a
192 _COMPONENT in an ACPI source file, e.g.,
193 #define _COMPONENT ACPI_PCI_COMPONENT
194 Bits in debug_level correspond to a level in
195 ACPI_DEBUG_PRINT statements, e.g.,
196 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
197 The debug_level mask defaults to "info". See
198 Documentation/acpi/debug.txt for more information about
199 debug layers and levels.
201 Enable processor driver info messages:
202 acpi.debug_layer=0x20000000
203 Enable PCI/PCI interrupt routing info messages:
204 acpi.debug_layer=0x400000
205 Enable AML "Debug" output, i.e., stores to the Debug
206 object while interpreting AML:
207 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
208 Enable all messages related to ACPI hardware:
209 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
211 Some values produce so much output that the system is
212 unusable. The "log_buf_len" parameter may be useful
213 if you need to capture more output.
215 acpi_irq_balance [HW,ACPI]
216 ACPI will balance active IRQs
219 acpi_irq_nobalance [HW,ACPI]
220 ACPI will not move active IRQs (default)
223 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224 Format: <irq>,<irq>...
226 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
228 Format: <irq>,<irq>...
230 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
232 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
233 Format: To spoof as Windows 98: ="Microsoft Windows"
235 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
236 acpi_osi="string1" # add string1 -- only one string
237 acpi_osi="!string2" # remove built-in string2
238 acpi_osi= # disable all strings
241 Override the pmtimer bug detection: force the kernel
242 to assume that this machine's pmtimer latches its value
243 and always returns good values.
245 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
246 Format: { level | edge | high | low }
248 acpi_serialize [HW,ACPI] force serialization of AML methods
250 acpi_skip_timer_override [HW,ACPI]
251 Recognize and ignore IRQ0/pin2 Interrupt Override.
252 For broken nForce2 BIOS resulting in XT-PIC timer.
254 acpi_sleep= [HW,ACPI] Sleep options
255 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
256 old_ordering, nonvs, sci_force_enable }
257 See Documentation/power/video.txt for information on
259 s3_beep is for debugging; it makes the PC's speaker beep
260 as soon as the kernel's real-mode entry point is called.
261 s4_nohwsig prevents ACPI hardware signature from being
262 used during resume from hibernation.
263 old_ordering causes the ACPI 1.0 ordering of the _PTS
264 control method, with respect to putting devices into
265 low power states, to be enforced (the ACPI 2.0 ordering
266 of _PTS is used by default).
267 nonvs prevents the kernel from saving/restoring the
268 ACPI NVS memory during suspend/hibernation and resume.
269 sci_force_enable causes the kernel to set SCI_EN directly
270 on resume from S1/S3 (which is against the ACPI spec,
271 but some broken systems don't work without it).
273 acpi_use_timer_override [HW,ACPI]
274 Use timer override. For some broken Nvidia NF5 boards
275 that require a timer override, but don't have HPET
277 acpi_enforce_resources= [ACPI]
278 { strict | lax | no }
279 Check for resource conflicts between native drivers
280 and ACPI OperationRegions (SystemIO and SystemMemory
281 only). IO ports and memory declared in ACPI might be
282 used by the ACPI subsystem in arbitrary AML code and
283 can interfere with legacy drivers.
284 strict (default): access to resources claimed by ACPI
285 is denied; legacy drivers trying to access reserved
286 resources will fail to bind to device using them.
287 lax: access to resources claimed by ACPI is allowed;
288 legacy drivers trying to access reserved resources
289 will bind successfully but a warning message is logged.
290 no: ACPI OperationRegions are not marked as reserved,
291 no further checks are performed.
293 add_efi_memmap [EFI; X86] Include EFI memory map in
294 kernel's map of available physical RAM.
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
303 See Documentation/sound/alsa/alsa-parameters.txt
306 Allow the default userspace alignment fault handler
307 behaviour to be specified. Bit 0 enables warnings,
308 bit 1 enables fixups, and bit 2 sends a segfault.
310 align_va_addr= [X86-64]
311 Align virtual addresses by clearing slice [14:12] when
312 allocating a VMA at process creation time. This option
313 gives you up to 3% performance improvement on AMD F15h
314 machines (where it is enabled by default) for a
315 CPU-intensive style benchmark, and it can vary highly in
316 a microbenchmark depending on workload and compiler.
318 32: only for 32-bit processes
319 64: only for 64-bit processes
320 on: enable for both 32- and 64-bit processes
321 off: disable for both 32- and 64-bit processes
323 amd_iommu= [HW,X86-64]
324 Pass parameters to the AMD IOMMU driver in the system.
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
330 off - do not initialize any AMD IOMMU found in
333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
336 See also Documentation/input/joystick.txt
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
344 Power management functions (SPARCstation-4/5 + deriv.)
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
351 Change the output verbosity whilst booting
352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
357 See Documentation/networking/ipv6.txt.
359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
368 apm= [APM] Advanced Power Management
369 See header of arch/x86/kernel/apm_32.c.
371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
376 atarimouse= [HW,MOUSE] Atari Mouse
378 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
379 EzKey and similar keyboards
381 atkbd.reset= [HW] Reset keyboard during initialization
383 atkbd.set= [HW] Select keyboard code set
384 Format: <int> (2 = AT (default), 3 = PS/2)
386 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 atkbd.softraw= [HW] Choose between synthetic and real raw mode
390 Format: <bool> (0 = real, 1 = synthetic (default))
392 atkbd.softrepeat= [HW]
393 Use software keyboard repeat
397 baycom_epp= [HW,AX25]
400 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
402 See header of drivers/net/hamradio/baycom_par.c.
404 baycom_ser_fdx= [HW,AX25]
405 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
406 Format: <io>,<irq>,<mode>[,<baud>]
407 See header of drivers/net/hamradio/baycom_ser_fdx.c.
409 baycom_ser_hdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
411 Format: <io>,<irq>,<mode>
412 See header of drivers/net/hamradio/baycom_ser_hdx.c.
414 boot_delay= Milliseconds to delay each printk during boot.
415 Values larger than 10 seconds (10000) are changed to
419 bootmem_debug [KNL] Enable bootmem allocator debug messages.
421 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
422 bttv.radio= Most important insmod options are available as
424 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bulk_remove=off [PPC] This parameter disables the use of the pSeries
428 firmware feature for flushing multiple hpte entries
431 c101= [NET] Moxa C101 synchronous serial card
433 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
434 Sometimes CPU hardware bugs make them report the cache
435 size incorrectly. The kernel will attempt work arounds
436 to fix known problems, but for some CPUs it is not
437 possible to determine what the correct size should be.
438 This option provides an override for these situations.
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
460 Value can be changed at runtime via
461 /selinux/checkreqprot.
464 See Documentation/s390/CommonIO for details.
466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
468 Forces specified clocksource (if available) to be used
469 when calculating gettimeofday(). If specified
470 clocksource is not available, it defaults to PIT.
471 Format: { pit | tsc | cyclone | pmtmr }
473 clocksource= Override the default clocksource
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
479 [all] jiffies (this is the base, fallback clocksource)
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
484 [X86-32] pit,hpet,tsc;
485 scx200_hrt on Geode; cyclone on IBM x440
493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
495 arch/x86/include/asm/cpufeature.h for the valid bit
496 numbers. Note the Linux specific bits are not necessarily
497 stable over kernel options, but the vendor specific
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
506 cmo_free_hint= [PPC] Format: { yes | no }
507 Specify whether pages are marked as being inactive
508 when they are freed. This is used in CMO environments
509 to determine OS memory pressure for page stealing by
513 code_bytes [X86] How many bytes of object code to print
518 com20020= [HW,NET] ARCnet - COM20020 chipset
520 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
522 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
526 ARCnet - COM90xx chipset (memory-mapped buffers)
527 Format: <io>[,<irq>[,<memstart>]]
529 condev= [HW,S390] console device
532 console= [KNL] Output console device and options.
534 tty<n> Use the virtual console device <n>.
538 Use the specified serial port. The options are of
539 the form "bbbbpnf", where "bbbb" is the baud rate,
540 "p" is parity ("n", "o", or "e"), "n" is number of
541 bits, and "f" is flow control ("r" for RTS or
542 omit it). Default is "9600n8".
544 See Documentation/serial-console.txt for more
546 Documentation/networking/netconsole.txt for an
549 uart[8250],io,<addr>[,options]
550 uart[8250],mmio,<addr>[,options]
551 Start an early, polled-mode console on the 8250/16550
552 UART at the specified I/O port or MMIO address,
553 switching to the matching ttyS device later. The
554 options are the same as for ttyS, above.
556 If the device connected to the port is not a TTY but a braille
557 device, prepend "brl," before the device type, for instance
559 For now, only VisioBraille is supported.
561 consoleblank= [KNL] The console blank (screen saver) timeout in
562 seconds. Defaults to 10*60 = 10mins. A value of 0
563 disables the blank timer.
566 [KNL] Change the default value for
567 /proc/<pid>/coredump_filter.
568 See also Documentation/filesystems/proc.txt.
570 cpuidle.off=1 [CPU_IDLE]
571 disable the cpuidle sub-system
573 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
575 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
577 crashkernel=size[KMG][@offset[KMG]]
578 [KNL] Using kexec, Linux can switch to a 'crash kernel'
579 upon panic. This parameter reserves the physical
580 memory region [offset, offset + size] for that kernel
581 image. If '@offset' is omitted, then a suitable offset
582 is selected automatically. Check
583 Documentation/kdump/kdump.txt for further details.
585 crashkernel=range1:size1[,range2:size2,...][@offset]
586 [KNL] Same as above, but depends on the memory
587 in the running system. The syntax of range is
588 start-[end] where start and end are both
589 a memory unit (amount[KMG]). See also
590 Documentation/kdump/kdump.txt for an example.
595 cs89x0_media= [HW,NET]
596 Format: { rj45 | aui | bnc }
599 See header of drivers/s390/block/dasd_devmap.c.
601 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
602 (one device per port)
603 Format: <port#>,<type>
604 See also Documentation/input/joystick-parport.txt
606 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
607 time. See Documentation/dynamic-debug-howto.txt for
610 debug [KNL] Enable kernel debugging (events log level).
613 [KNL] verbose self-tests
615 Print debugging info while doing the locking API
617 We default to 0 (no extra messages), setting it to
618 1 will print _a lot_ more information - normally
619 only useful to kernel developers.
621 debug_objects [KNL] Enable object debugging
624 [KNL] Disable object debugging
626 debugpat [X86] Enable PAT debugging
628 decnet.addr= [HW,NET]
629 Format: <area>[,<node>]
630 See also Documentation/networking/decnet.txt.
633 [same as hugepagesz=] The size of the default
634 HugeTLB page size. This is the size represented by
635 the legacy /proc/ hugepages APIs, used for SHM, and
636 default size when mounting hugetlbfs filesystems.
637 Defaults to the default architecture's huge page size
641 Set number of hash buckets for dentry cache.
644 IO parameters + enable/disable command.
646 digiepca= [HW,SERIAL]
647 See drivers/char/README.epca and
648 Documentation/serial/digiepca.txt.
651 See Documentation/networking/ipv6.txt.
653 disable_ddw [PPC/PSERIES]
654 Disable Dynamic DMA Window support. Use this if
655 to workaround buggy firmware.
658 See Documentation/networking/ipv6.txt.
660 disable_mtrr_cleanup [X86]
661 The kernel tries to adjust MTRR layout from continuous
662 to discrete, to make X server driver able to add WB
663 entry later. This parameter disables that.
665 disable_mtrr_trim [X86, Intel and AMD only]
666 By default the kernel will trim any uncacheable
667 memory out of your available memory pool based on
668 MTRR settings. This parameter disables that behavior,
669 possibly causing your machine to run very slowly.
671 disable_timer_pin_1 [X86]
672 Disable PIN 1 of APIC timer
673 Can be useful to work around chipset bugs.
675 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
676 this option disables the debugging code at boot.
678 dma_debug_entries=<number>
679 This option allows to tune the number of preallocated
680 entries for DMA-API debugging code. One entry is
681 required per DMA-API allocation. Use this if the
682 DMA-API debugging code disables itself because the
683 architectural default is too low.
685 dma_debug_driver=<driver_name>
686 With this option the DMA-API debugging driver
687 filter feature can be enabled at boot time. Just
688 pass the driver to filter for as the parameter.
689 The filter can be disabled or changed to another
690 driver later using sysfs.
694 earlycon= [KNL] Output early console device and options.
695 uart[8250],io,<addr>[,options]
696 uart[8250],mmio,<addr>[,options]
697 uart[8250],mmio32,<addr>[,options]
698 Start an early, polled-mode console on the 8250/16550
699 UART at the specified I/O port or MMIO address.
700 MMIO inter-register address stride is either 8-bit
701 (mmio) or 32-bit (mmio32).
702 The options are the same as for ttyS, above.
704 earlyprintk= [X86,SH,BLACKFIN]
706 earlyprintk=serial[,ttySn[,baudrate]]
707 earlyprintk=ttySn[,baudrate]
708 earlyprintk=dbgp[debugController#]
710 Append ",keep" to not disable it when the real console
713 Only vga or serial or usb debug port at a time.
715 Currently only ttyS0 and ttyS1 are supported.
717 Interaction with the standard serial driver is not
720 The VGA output is eventually overwritten by the real
723 ekgdboc= [X86,KGDB] Allow early kernel console debugging
726 This is designed to be used in conjunction with
727 the boot argument: earlyprintk=vga
730 Format: {"off" | "on" | "skip[mbr]"}
732 eisa_irq_edge= [PARISC,HW]
733 See header of drivers/parisc/eisa.c.
736 See comment before function elanfreq_setup() in
737 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
740 Format: {"cfq" | "deadline" | "noop"}
741 See Documentation/block/cfq-iosched.txt and
742 Documentation/block/deadline-iosched.txt for details.
744 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
745 Specifies physical address of start of kernel core
746 image elf header and optionally the size. Generally
747 kexec loader will pass this option to capture kernel.
748 See Documentation/kdump/kdump.txt for details.
750 enable_mtrr_cleanup [X86]
751 The kernel tries to adjust MTRR layout from continuous
752 to discrete, to make X server driver able to add WB
753 entry later. This parameter enables that.
755 enable_timer_pin_1 [X86]
756 Enable PIN 1 of APIC timer
757 Can be useful to work around chipset bugs
758 (in particular on some ATI chipsets).
759 The kernel tries to set a reasonable default.
761 enforcing [SELINUX] Set initial enforcing status.
763 See security/selinux/Kconfig help text.
764 0 -- permissive (log only, no denials).
765 1 -- enforcing (deny and log).
767 Value can be changed at runtime via /selinux/enforce.
770 Disable Error Record Serialization Table (ERST)
773 ether= [HW,NET] Ethernet cards parameters
774 This option is obsoleted by the "netdev=" option, which
775 has equivalent usage. See its documentation for details.
779 Permit 'security.evm' to be updated regardless of
780 current integrity status.
784 fail_make_request=[KNL]
785 General fault injection mechanism.
786 Format: <interval>,<probability>,<space>,<times>
787 See also Documentation/fault-injection/.
790 See Documentation/blockdev/floppy.txt.
792 force_pal_cache_flush
793 [IA-64] Avoid check_sal_cache_flush which may hang on
794 buggy SAL_CACHE_FLUSH implementations. Using this
795 parameter will force ia64_sal_cache_flush to call
796 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
799 [FTRACE] will set and start the specified tracer
800 as early as possible in order to facilitate early
803 ftrace_dump_on_oops[=orig_cpu]
804 [FTRACE] will dump the trace buffers on oops.
805 If no parameter is passed, ftrace will dump
806 buffers of all CPUs, but if you pass orig_cpu, it will
807 dump only the buffer of the CPU that triggered the
810 ftrace_filter=[function-list]
811 [FTRACE] Limit the functions traced by the function
812 tracer at boot up. function-list is a comma separated
813 list of functions. This list can be changed at run
814 time by the set_ftrace_filter file in the debugfs
817 ftrace_notrace=[function-list]
818 [FTRACE] Do not trace the functions specified in
819 function-list. This list can be changed at run time
820 by the set_ftrace_notrace file in the debugfs
823 ftrace_graph_filter=[function-list]
824 [FTRACE] Limit the top level callers functions traced
825 by the function graph tracer at boot up.
826 function-list is a comma separated list of functions
827 that can be changed at run time by the
828 set_graph_function file in the debugfs tracing directory.
831 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
832 support via parallel port (up to 5 devices per port)
833 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
834 See also Documentation/input/joystick-parport.txt
838 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
842 gcov_persist= [GCOV] When non-zero (default), profiling data for
843 kernel modules is saved and remains accessible via
844 debugfs, even when the module is unloaded/reloaded.
845 When zero, profiling data is discarded and associated
846 debugfs files are removed at module unload time.
848 gpt [EFI] Forces disk with valid GPT signature but
849 invalid Protective MBR to be treated as GPT.
851 hashdist= [KNL,NUMA] Large hashes allocated during boot
852 are distributed across NUMA nodes. Defaults on
853 for 64-bit NUMA, off otherwise.
854 Format: 0 | 1 (for off | on)
856 hcl= [IA-64] SGI's Hardware Graph compatibility layer
858 hd= [EIDE] (E)IDE hard drive subsystem geometry
859 Format: <cyl>,<head>,<sect>
862 Disable Hardware Error Source Table (HEST) support;
863 corresponding firmware-first mode error processing
864 logic will be disabled.
866 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
867 size of <nn>. This works even on boxes that have no
868 highmem otherwise. This also works to reduce highmem
869 size on bigger boxes.
871 highres= [KNL] Enable/disable high resolution timer mode.
872 Valid parameters: "on", "off"
876 See Documentation/isdn/README.HiSax.
880 hpet= [X86-32,HPET] option to control HPET usage
881 Format: { enable (default) | disable | force |
883 disable: disable HPET and use PIT instead
884 force: allow force enabled of undocumented chips (ICH4,
886 verbose: show contents of HPET registers during setup
888 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
889 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
890 On x86-64 and powerpc, this option can be specified
891 multiple times interleaved with hugepages= to reserve
892 huge pages of different sizes. Valid pages sizes on
893 x86-64 are 2M (when the CPU supports "pse") and 1G
894 (when the CPU supports the "pdpe1gb" cpuinfo flag)
895 Note that 1GB pages can only be allocated at boot time
896 using hugepages= and not freed afterwards.
898 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
899 terminal devices. Valid values: 0..8
900 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
901 If specified, z/VM IUCV HVC accepts connections
902 from listed z/VM user IDs only.
905 Do not unregister boot console at start. This is only
906 useful for debugging when something happens in the window
907 between unregistering the boot console and initializing
910 i2c_bus= [HW] Override the default board specific I2C bus speed
911 or register an additional I2C bus that is not
912 registered from board initialization code.
916 i8042.debug [HW] Toggle i8042 debug mode
917 i8042.direct [HW] Put keyboard port into non-translated mode
918 i8042.dumbkbd [HW] Pretend that controller can only read data from
919 keyboard and cannot control its state
920 (Don't attempt to blink the leds)
921 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
922 i8042.nokbd [HW] Don't check/create keyboard port
923 i8042.noloop [HW] Disable the AUX Loopback command while probing
925 i8042.nomux [HW] Don't check presence of an active multiplexing
927 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
929 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
930 i8042.reset [HW] Reset the controller during init and cleanup
931 i8042.unlock [HW] Unlock (ignore) the keylock
935 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
936 indicates that the driver is running on unsupported
938 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
939 does not match list of supported models.
941 [HW] Report power status in /proc/i8k
942 (disabled by default)
943 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
947 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
949 ide-core.nodma= [HW] (E)IDE subsystem
950 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
951 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
952 .cdrom .chs .ignore_cable are additional options
953 See Documentation/ide/ide.txt.
955 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
956 Claim all unknown PCI IDE storage controllers.
959 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
960 Poll forces a polling idle loop that can slightly
961 improve the performance of waking up a idle CPU, but
962 will use a lot of power and make the system run hot.
964 idle=mwait: On systems which support MONITOR/MWAIT but
965 the kernel chose to not use it because it doesn't save
966 as much power as a normal idle loop, use the
967 MONITOR/MWAIT idle loop anyways. Performance should be
968 the same as idle=poll.
969 idle=halt: Halt is forced to be used for CPU idle.
970 In such case C2/C3 won't be used again.
971 idle=nomwait: Disable mwait for CPU C-states
973 ignore_loglevel [KNL]
974 Ignore loglevel setting - this will print /all/
975 kernel messages to the console. Useful for debugging.
976 We also add it as printk module parameter, so users
977 could change it dynamically, usually by
978 /sys/module/printk/parameters/ignore_loglevel.
981 Set number of hash buckets for inode cache.
984 Format: { "0" | "1" }
985 0 -- integrity auditing messages. (Default)
986 1 -- enable informational integrity auditing messages.
989 Format: { "sha1" | "md5" }
993 Load a policy which meets the needs of the Trusted
994 Computing Base. This means IMA will measure all
995 programs exec'd, files mmap'd for exec, and all files
996 opened for read by uid=0.
1000 Run specified binary instead of /sbin/init as init
1003 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1004 for working out where the kernel is dying during
1007 initrd= [BOOT] Specify the location of the initial ramdisk
1009 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1012 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1014 Enable intel iommu driver.
1016 Disable intel iommu driver.
1017 igfx_off [Default Off]
1018 By default, gfx is mapped as normal device. If a gfx
1019 device has a dedicated DMAR unit, the DMAR unit is
1020 bypassed by not enabling DMAR with this option. In
1021 this case, gfx device will use physical address for
1024 With this option iommu will not optimize to look
1025 for io virtual address below 32-bit forcing dual
1026 address cycle on pci bus for cards supporting greater
1027 than 32-bit addressing. The default is to look
1028 for translation below 32-bit and if not available
1029 then look in the higher range.
1030 strict [Default Off]
1031 With this option on every unmap_single operation will
1032 result in a hardware IOTLB flush operation as opposed
1033 to batching them for performance.
1034 sp_off [Default Off]
1035 By default, super page will be supported if Intel IOMMU
1036 has the capability. With this option, super page will
1038 intremap= [X86-64, Intel-IOMMU]
1039 on enable Interrupt Remapping (default)
1040 off disable Interrupt Remapping
1041 nosid disable Source ID checking
1043 BIOS x2APIC opt-out request will be ignored
1047 iomem= Disable strict checking of access to MMIO memory
1048 strict regions from userspace.
1064 io7= [HW] IO7 for Marvel based alpha systems
1065 See comment before marvel_specify_io7 in
1066 arch/alpha/kernel/core_marvel.c.
1068 io_delay= [X86] I/O delay method
1070 Standard port 0x80 based delay
1072 Alternate port 0xed based delay (needed on some systems)
1074 Simple two microseconds delay
1079 See Documentation/filesystems/nfs/nfsroot.txt.
1081 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1082 See comment before ip2_setup() in
1083 drivers/char/ip2/ip2base.c.
1086 When an interrupt is not handled search all handlers
1087 for it. Intended to get systems with badly broken
1091 When an interrupt is not handled search all handlers
1092 for it. Also check all handlers each timer
1093 interrupt. Intended to get systems with badly broken
1097 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1099 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1101 <cpu number>,...,<cpu number>
1103 <cpu number>-<cpu number>
1104 (must be a positive range in ascending order)
1106 <cpu number>,...,<cpu number>-<cpu number>
1108 This option can be used to specify one or more CPUs
1109 to isolate from the general SMP balancing and scheduling
1110 algorithms. You can move a process onto or off an
1111 "isolated" CPU via the CPU affinity syscalls or cpuset.
1112 <cpu number> begins at 0 and the maximum value is
1113 "number of CPUs in system - 1".
1115 This option is the preferred way to isolate CPUs. The
1116 alternative -- manually setting the CPU mask of all
1117 tasks in the system -- can cause problems and
1118 suboptimal load balancer performance.
1122 js= [HW,JOY] Analog joystick
1123 See Documentation/input/joystick.txt.
1127 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1128 specifies the amount of memory usable by the kernel
1129 for non-movable allocations. The requested amount is
1130 spread evenly throughout all nodes in the system. The
1131 remaining memory in each node is used for Movable
1132 pages. In the event, a node is too small to have both
1133 kernelcore and Movable pages, kernelcore pages will
1134 take priority and other nodes will have a larger number
1135 of kernelcore pages. The Movable zone is used for the
1136 allocation of pages that may be reclaimed or moved
1137 by the page migration subsystem. This means that
1138 HugeTLB pages may not be allocated from this zone.
1139 Note that allocations like PTEs-from-HighMem still
1140 use the HighMem zone if it exists, and the Normal
1141 zone if it does not.
1143 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1144 Format: <Controller#>[,poll interval]
1145 The controller # is the number of the ehci usb debug
1146 port as it is probed via PCI. The poll interval is
1147 optional and is the number seconds in between
1148 each poll cycle to the debug port in case you need
1149 the functionality for interrupting the kernel with
1150 gdb or control-c on the dbgp connection. When
1151 not using this parameter you use sysrq-g to break into
1152 the kernel debugger.
1154 kgdboc= [KGDB,HW] kgdb over consoles.
1155 Requires a tty driver that supports console polling,
1156 or a supported polling keyboard driver (non-usb).
1157 Serial only format: <serial_device>[,baud]
1158 keyboard only format: kbd
1159 keyboard and serial format: kbd,<serial_device>[,baud]
1160 Optional Kernel mode setting:
1161 kms, kbd format: kms,kbd
1162 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1164 kgdbwait [KGDB] Stop kernel execution and enter the
1165 kernel debugger at the earliest opportunity.
1167 kmac= [MIPS] korina ethernet MAC address.
1168 Configure the RouterBoard 532 series on-chip
1169 Ethernet adapter MAC address.
1171 kmemleak= [KNL] Boot-time kmemleak enable/disable
1172 Valid arguments: on, off
1175 kstack=N [X86] Print N words from the kernel stack
1178 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1179 Default is 0 (don't ignore, but inject #GP)
1181 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1185 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1186 Default is 1 (enabled)
1188 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1190 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1192 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1193 (virtualized MMU) support on capable Intel chips.
1194 Default is 1 (enabled)
1196 kvm-intel.emulate_invalid_guest_state=
1197 [KVM,Intel] Enable emulation of invalid guest states
1198 Default is 0 (disabled)
1200 kvm-intel.flexpriority=
1201 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1202 Default is 1 (enabled)
1205 [KVM,Intel] Enable VMX nesting (nVMX).
1206 Default is 0 (disabled)
1208 kvm-intel.unrestricted_guest=
1209 [KVM,Intel] Disable unrestricted guest feature
1210 (virtualized real and unpaged mode) on capable
1211 Intel chips. Default is 1 (enabled)
1213 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1214 feature (tagged TLBs) on capable Intel chips.
1215 Default is 1 (enabled)
1221 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1224 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1227 libata.dma= [LIBATA] DMA control
1228 libata.dma=0 Disable all PATA and SATA DMA
1229 libata.dma=1 PATA and SATA Disk DMA only
1230 libata.dma=2 ATAPI (CDROM) DMA only
1231 libata.dma=4 Compact Flash DMA only
1232 Combinations also work, so libata.dma=3 enables DMA
1233 for disks and CDROMs, but not CFs.
1235 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1236 libata.ignore_hpa=0 keep BIOS limits (default)
1237 libata.ignore_hpa=1 ignore limits, using full disk
1239 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1243 libata.force= [LIBATA] Force configurations. The format is comma
1244 separated list of "[ID:]VAL" where ID is
1245 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1246 matching port, link or device. Basically, it matches
1247 the ATA ID string printed on console by libata. If
1248 the whole ID part is omitted, the last PORT and DEVICE
1249 values are used. If ID hasn't been specified yet, the
1250 configuration applies to all ports, links and devices.
1252 If only DEVICE is omitted, the parameter applies to
1253 the port and all links and devices behind it. DEVICE
1254 number of 0 either selects the first device or the
1255 first fan-out link behind PMP device. It does not
1256 select the host link. DEVICE number of 15 selects the
1257 host link and device attached to it.
1259 The VAL specifies the configuration to force. As long
1260 as there's no ambiguity shortcut notation is allowed.
1261 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1262 The following configurations can be forced.
1264 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1265 Any ID with matching PORT is used.
1267 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1269 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1270 udma[/][16,25,33,44,66,100,133] notation is also
1273 * [no]ncq: Turn on or off NCQ.
1275 * nohrst, nosrst, norst: suppress hard, soft
1278 * dump_id: dump IDENTIFY data.
1280 If there are multiple matching configurations changing
1281 the same attribute, the last one is used.
1283 memblock=debug [KNL] Enable memblock debug messages.
1285 load_ramdisk= [RAM] List of ramdisks to load from floppy
1286 See Documentation/blockdev/ramdisk.txt.
1288 lockd.nlm_grace_period=P [NFS] Assign grace period.
1291 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1294 lockd.nlm_timeout=T [NFS] Assign timeout value.
1297 lockd.nlm_udpport=M [NFS] Assign UDP port.
1300 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1303 loglevel= All Kernel Messages with a loglevel smaller than the
1304 console loglevel will be printed to the console. It can
1305 also be changed with klogd or other programs. The
1306 loglevels are defined as follows:
1308 0 (KERN_EMERG) system is unusable
1309 1 (KERN_ALERT) action must be taken immediately
1310 2 (KERN_CRIT) critical conditions
1311 3 (KERN_ERR) error conditions
1312 4 (KERN_WARNING) warning conditions
1313 5 (KERN_NOTICE) normal but significant condition
1314 6 (KERN_INFO) informational
1315 7 (KERN_DEBUG) debug-level messages
1317 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1318 in bytes. n must be a power of two. The default
1319 size is set in the kernel config file.
1321 logo.nologo [FB] Disables display of the built-in Linux logo.
1322 This may be used to provide more screen space for
1323 kernel log messages and is useful when debugging
1324 kernel boot problems.
1326 lp=0 [LP] Specify parallel ports to use, e.g,
1327 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1328 lp=reset first parallel port). 'lp=0' disables the
1329 lp=auto printer driver. 'lp=reset' (which can be
1330 specified in addition to the ports) causes
1331 attached printers to be reset. Using
1332 lp=port1,port2,... specifies the parallel ports
1333 to associate lp devices with, starting with
1334 lp0. A port specification may be 'none' to skip
1335 that lp device, or a parport name such as
1336 'parport0'. Specifying 'lp=auto' instead of a
1337 port specification list means that device IDs
1338 from each port should be examined, to see if
1339 an IEEE 1284-compliant printer is attached; if
1340 so, the driver will manage that printer.
1341 See also header of drivers/char/lp.c.
1344 Sets loops_per_jiffy to given constant, thus avoiding
1345 time-consuming boot-time autodetection (up to 250 ms per
1346 CPU). 0 enables autodetection (default). To determine
1347 the correct value for your kernel, boot with normal
1348 autodetection and see what value is printed. Note that
1349 on SMP systems the preset will be applied to all CPUs,
1350 which is likely to cause problems if your CPUs need
1351 significantly divergent settings. An incorrect value
1352 will cause delays in the kernel to be wrong, leading to
1353 unpredictable I/O errors and other breakage. Although
1354 unlikely, in the extreme case this might damage your
1358 Format: <io>,<irq>,<dma>
1360 machvec= [IA-64] Force the use of a particular machine-vector
1361 (machvec) in a generic kernel.
1362 Example: machvec=hpzx1_swiotlb
1364 machtype= [Loongson] Share the same kernel image file between different
1366 Example: machtype=lemote-yeeloong-2f-7inch
1368 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1369 than or equal to this physical address is ignored.
1371 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1372 should make use of. maxcpus=n : n >= 0 limits the
1373 kernel to using 'n' processors. n=0 is a special case,
1374 it is equivalent to "nosmp", which also disables
1377 max_loop= [LOOP] The number of loop block devices that get
1378 (loop.max_loop) unconditionally pre-created at init time. The default
1379 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1380 of statically allocating a predefined number, loop
1381 devices can be requested on-demand with the
1382 /dev/loop-control interface.
1386 mce [X86-32] Machine Check Exception
1388 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1390 md= [HW] RAID subsystems devices and level
1391 See Documentation/md.txt.
1394 Format: <first>,<last>
1395 Specifies range of consoles to be captured by the MDA.
1397 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1398 Amount of memory to be used when the kernel is not able
1399 to see the whole system memory or for test.
1400 [X86-32] Use together with memmap= to avoid physical
1401 address space collisions. Without memmap= PCI devices
1402 could be placed at addresses belonging to unused RAM.
1404 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1408 [KNL,SH] Allow user to override the default size for
1409 per-device physically contiguous DMA buffers.
1411 memmap=exactmap [KNL,X86] Enable setting of an exact
1412 E820 memory map, as specified by the user.
1413 Such memmap=exactmap lines can be constructed based on
1414 BIOS output or other requirements. See the memmap=nn@ss
1417 memmap=nn[KMG]@ss[KMG]
1418 [KNL] Force usage of a specific region of memory
1419 Region of memory to be used, from ss to ss+nn.
1421 memmap=nn[KMG]#ss[KMG]
1422 [KNL,ACPI] Mark specific memory as ACPI data.
1423 Region of memory to be used, from ss to ss+nn.
1425 memmap=nn[KMG]$ss[KMG]
1426 [KNL,ACPI] Mark specific memory as reserved.
1427 Region of memory to be used, from ss to ss+nn.
1428 Example: Exclude memory from 0x18690000-0x1869ffff
1429 memmap=64K$0x18690000
1431 memmap=0x10000$0x18690000
1433 memory_corruption_check=0/1 [X86]
1434 Some BIOSes seem to corrupt the first 64k of
1435 memory when doing things like suspend/resume.
1436 Setting this option will scan the memory
1437 looking for corruption. Enabling this will
1438 both detect corruption and prevent the kernel
1439 from using the memory being corrupted.
1440 However, its intended as a diagnostic tool; if
1441 repeatable BIOS-originated corruption always
1442 affects the same memory, you can use memmap=
1443 to prevent the kernel from using that memory.
1445 memory_corruption_check_size=size [X86]
1446 By default it checks for corruption in the low
1447 64k, making this memory unavailable for normal
1448 use. Use this parameter to scan for
1449 corruption in more or less memory.
1451 memory_corruption_check_period=seconds [X86]
1452 By default it checks for corruption every 60
1453 seconds. Use this parameter to check at some
1454 other rate. 0 disables periodic checking.
1456 memtest= [KNL,X86] Enable memtest
1458 default : 0 <disable>
1459 Specifies the number of memtest passes to be
1460 performed. Each pass selects another test
1461 pattern from a given set of patterns. Memtest
1462 fills the memory with this pattern, validates
1463 memory contents and reserves bad memory
1464 regions that are detected.
1466 meye.*= [HW] Set MotionEye Camera parameters
1467 See Documentation/video4linux/meye.txt.
1469 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1470 Multi-Function General Purpose Timers on AMD Geode
1473 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1474 the BIOS has incorrectly applied a workaround. TinyBIOS
1475 version 0.98 is known to be affected, 0.99 fixes the
1476 problem by letting the user disable the workaround.
1480 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1481 physical address is ignored.
1483 mini2440= [ARM,HW,KNL]
1484 Format:[0..2][b][c][t]
1486 MINI2440 configuration specification:
1487 0 - The attached screen is the 3.5" TFT
1488 1 - The attached screen is the 7" TFT
1489 2 - The VGA Shield is attached (1024x768)
1490 Leaving out the screen size parameter will not load
1491 the TFT driver, and the framebuffer will be left
1493 b - Enable backlight. The TFT backlight pin will be
1494 linked to the kernel VESA blanking code and a GPIO
1495 LED. This parameter is not necessary when using the
1497 c - Enable the s3c camera interface.
1498 t - Reserved for enabling touchscreen support. The
1499 touchscreen support is not enabled in the mainstream
1500 kernel as of 2.6.30, a preliminary port can be found
1501 in the "bleeding edge" mini2440 support kernel at
1502 http://repo.or.cz/w/linux-2.6/mini2440.git
1505 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1506 parameter allows control of the logging verbosity for
1507 the additional memory initialisation checks. A value
1508 of 0 disables mminit logging and a level of 4 will
1509 log everything. Information is printed at KERN_DEBUG
1510 so loglevel=8 may also need to be specified.
1513 [MOUSE] Maximum time between finger touching and
1514 leaving touchpad surface for touch to be considered
1515 a tap and be reported as a left button click (for
1516 touchpads working in absolute mode only).
1518 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1519 reporting absolute coordinates, such as tablets
1520 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1521 reporting absolute coordinates, such as tablets
1523 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1524 is similar to kernelcore except it specifies the
1525 amount of memory used for migratable allocations.
1526 If both kernelcore and movablecore is specified,
1527 then kernelcore will be at *least* the specified
1528 value but may be more. If movablecore on its own
1529 is specified, the administrator must be careful
1530 that the amount of memory usable for all allocations
1533 MTD_Partition= [MTD]
1534 Format: <name>,<region-number>,<size>,<offset>
1536 MTD_Region= [MTD] Format:
1537 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1540 See drivers/mtd/cmdlinepart.c.
1542 multitce=off [PPC] This parameter disables the use of the pSeries
1543 firmware feature for updating multiple TCE entries
1546 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1548 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1550 boundary - index of last SLC block on Flex-OneNAND.
1551 The remaining blocks are configured as MLC blocks.
1552 lock - Configure if Flex-OneNAND boundary should be locked.
1553 Once locked, the boundary cannot be changed.
1554 1 indicates lock status, 0 indicates unlock status.
1557 ARM/S3C2412 JIVE boot control
1559 See arch/arm/mach-s3c2412/mach-jive.c
1561 mtouchusb.raw_coordinates=
1562 [HW] Make the MicroTouch USB driver use raw coordinates
1563 ('y', default) or cooked coordinates ('n')
1565 mtrr_chunk_size=nn[KMG] [X86]
1566 used for mtrr cleanup. It is largest continuous chunk
1567 that could hold holes aka. UC entries.
1569 mtrr_gran_size=nn[KMG] [X86]
1570 Used for mtrr cleanup. It is granularity of mtrr block.
1572 Large value could prevent small alignment from
1575 mtrr_spare_reg_nr=n [X86]
1577 Range: 0,7 : spare reg number
1579 Used for mtrr cleanup. It is spare mtrr entries number.
1580 Set to 2 or more if your graphical card needs more.
1582 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1584 netdev= [NET] Network devices parameters
1585 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1586 Note that mem_start is often overloaded to mean
1587 something different and driver-specific.
1588 This usage is only documented in each driver source
1592 [NETFILTER] Enable connection tracking flow accounting
1593 0 to disable accounting
1594 1 to enable accounting
1597 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1598 See Documentation/filesystems/nfs/nfsroot.txt.
1600 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1601 See Documentation/filesystems/nfs/nfsroot.txt.
1603 nfsrootdebug [NFS] enable nfsroot debugging messages.
1604 See Documentation/filesystems/nfs/nfsroot.txt.
1606 nfs.callback_tcpport=
1607 [NFS] set the TCP port on which the NFSv4 callback
1608 channel should listen.
1611 [NFS] sets the pathname to the program which is used
1612 to update the NFS client cache entries.
1614 nfs.cache_getent_timeout=
1615 [NFS] sets the timeout after which an attempt to
1616 update a cache entry is deemed to have failed.
1618 nfs.idmap_cache_timeout=
1619 [NFS] set the maximum lifetime for idmapper cache
1623 [NFS] enable 64-bit inode numbers.
1624 If zero, the NFS client will fake up a 32-bit inode
1625 number for the readdir() and stat() syscalls instead
1626 of returning the full 64-bit number.
1627 The default is to return 64-bit inode numbers.
1629 nfs.nfs4_disable_idmapping=
1630 [NFSv4] When set, this option disables the NFSv4
1631 idmapper on the client, but only if the mount
1632 is using the 'sec=sys' security flavour. This may
1633 make migration from legacy NFSv2/v3 systems easier
1634 provided that the server has the appropriate support.
1635 The default is to always enable NFSv4 idmapping.
1637 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1638 when a NMI is triggered.
1639 Format: [state][,regs][,debounce][,die]
1641 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1642 Format: [panic,][nopanic,][num]
1644 0 - turn nmi_watchdog off
1645 When panic is specified, panic when an NMI watchdog
1646 timeout occurs (or 'nopanic' to override the opposite
1648 This is useful when you use a panic=... timeout and
1649 need the box quickly up again.
1651 netpoll.carrier_timeout=
1652 [NET] Specifies amount of time (in seconds) that
1653 netpoll should wait for a carrier. By default netpoll
1656 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1657 emulation library even if a 387 maths coprocessor
1661 [HW] Never suspend the console
1662 Disable suspending of consoles during suspend and
1663 hibernate operations. Once disabled, debugging
1664 messages can reach various consoles while the rest
1665 of the system is being put to sleep (ie, while
1666 debugging driver suspend/resume hooks). This may
1667 not work reliably with all consoles, but is known
1668 to work with serial and VGA consoles.
1669 To facilitate more flexible debugging, we also add
1670 console_suspend, a printk module parameter to control
1671 it. Users could use console_suspend (usually
1672 /sys/module/printk/parameters/console_suspend) to
1673 turn on/off it dynamically.
1675 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1676 caches in the slab allocator. Saves per-node memory,
1677 but will impact performance.
1681 noapic [SMP,APIC] Tells the kernel to not make use of any
1682 IOAPICs that may be present in the system.
1684 noautogroup Disable scheduler automatic task group creation.
1686 nobats [PPC] Do not use BATs for mapping kernel lowmem
1687 on "Classic" PPC cores.
1691 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1693 nodelayacct [KNL] Disable per-task delay accounting
1695 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1697 nodsp [SH] Disable hardware DSP at boot time.
1699 noefi [X86] Disable EFI runtime services support.
1704 On X86-32 available only on PAE configured kernels.
1705 noexec=on: enable non-executable mappings (default)
1706 noexec=off: disable non-executable mappings
1709 Disable SMEP (Supervisor Mode Execution Protection)
1710 even if it is supported by processor.
1713 This affects only 32-bit executables.
1714 noexec32=on: enable non-executable mappings (default)
1715 read doesn't imply executable mappings
1716 noexec32=off: disable non-executable mappings
1717 read implies executable mappings
1719 nofpu [SH] Disable hardware FPU at boot time.
1721 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1722 register save and restore. The kernel will only save
1723 legacy floating-point registers on task switch.
1725 noxsave [BUGS=X86] Disables x86 extended register state save
1726 and restore using xsave. The kernel will fallback to
1727 enabling legacy floating-point and sse state.
1729 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1730 wfi(ARM) instruction doesn't work correctly and not to
1731 use it. This is also useful when using JTAG debugger.
1733 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1734 instruction doesn't work correctly and not to
1737 no_file_caps Tells the kernel not to honor file capabilities. The
1738 only way then for a file to be executed with privilege
1739 is to be setuid root or executed by root.
1741 nohalt [IA-64] Tells the kernel not to use the power saving
1742 function PAL_HALT_LIGHT when idle. This increases
1743 power-consumption. On the positive side, it reduces
1744 interrupt wake-up latency, which may improve performance
1745 in certain environments such as networked servers or
1748 nohz= [KNL] Boottime enable/disable dynamic ticks
1749 Valid arguments: on, off
1752 noiotrap [SH] Disables trapped I/O port accesses.
1754 noirqdebug [X86-32] Disables the code which attempts to detect and
1755 disable unhandled interrupt sources.
1757 no_timer_check [X86,APIC] Disables the code which tests for
1758 broken timer IRQ sources.
1760 noisapnp [ISAPNP] Disables ISA PnP code.
1762 noinitrd [RAM] Tells the kernel not to load any configured
1765 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1767 [Deprecated - use intremap=off]
1771 nojitter [IA-64] Disables jitter checking for ITC timers.
1773 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1775 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1778 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1779 steal time is computed, but won't influence scheduler
1782 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1784 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1786 noltlbs [PPC] Do not use large page/tlb entries for kernel
1787 lowmem mapping on PPC40x.
1789 nomca [IA-64] Disable machine check abort handling
1791 nomce [X86-32] Machine Check Exception
1793 nomfgpt [X86-32] Disable Multi-Function General Purpose
1794 Timer usage (for AMD Geode machines).
1796 nopat [X86] Disable PAT (page attribute table extension of
1797 pagetables) support.
1799 norandmaps Don't use address space randomization. Equivalent to
1800 echo 0 > /proc/sys/kernel/randomize_va_space
1802 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1804 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1805 with UP alternatives
1807 noresidual [PPC] Don't use residual data on PReP machines.
1809 nordrand [X86] Disable the direct use of the RDRAND
1810 instruction even if it is supported by the
1811 processor. RDRAND is still available to user
1814 noresume [SWSUSP] Disables resume and restores original swap
1817 no-scroll [VGA] Disables scrollback.
1818 This is required for the Braillex ib80-piezo Braille
1819 reader made by F.H. Papenmeier (Germany).
1823 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1825 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1826 and disable the IO APIC. legacy for "maxcpus=0".
1828 nosoftlockup [KNL] Disable the soft-lockup detector.
1830 nosync [HW,M68K] Disables sync negotiation for all devices.
1832 notsc [BUGS=X86-32] Disable Time Stamp Counter
1834 nousb [USB] Disable the USB subsystem
1836 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1840 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1842 nptcg= [IA-64] Override max number of concurrent global TLB
1843 purges which is reported from either PAL_VM_SUMMARY or
1846 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1847 could support. nr_cpus=n : n >= 1 limits the kernel to
1848 supporting 'n' processors. Later in runtime you can not
1849 use hotplug cpu feature to put more cpu back to online.
1850 just like you compile the kernel NR_CPUS=n
1852 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1854 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1855 one of ['zone', 'node', 'default'] can be specified
1856 This can be set from sysctl after boot.
1857 See Documentation/sysctl/vm.txt for details.
1859 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1860 See Documentation/debugging-via-ohci1394.txt for more
1863 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1864 Rather than timing out after 20 ms if an EC
1865 command is not properly ACKed, override the length
1866 of the timeout. We have interrupts disabled while
1867 waiting for the ACK, so if this is set too high
1868 interrupts *may* be lost!
1870 omap_mux= [OMAP] Override bootloader pin multiplexing.
1871 Format: <mux_mode0.mode_name=value>...
1872 For example, to override I2C bus2:
1873 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1875 oprofile.timer= [HW]
1876 Use timer interrupt instead of performance counters
1878 oprofile.cpu_type= Force an oprofile cpu type
1879 This might be useful if you have an older oprofile
1880 userland or if you want common events.
1881 Format: { arch_perfmon }
1882 arch_perfmon: [X86] Force use of architectural
1883 perfmon on Intel CPUs instead of the
1884 CPU specific event set.
1885 timer: [X86] Force use of architectural NMI
1886 timer mode (see also oprofile.timer
1887 for generic hr timer mode)
1888 [s390] Force legacy basic mode sampling
1889 (report cpu_type "timer")
1891 oops=panic Always panic on oopses. Default is to just kill the
1892 process, but there is a small probability of
1893 deadlocking the machine.
1894 This will also cause panics on machine check exceptions.
1895 Useful together with panic=30 to trigger a reboot.
1898 See Documentation/sound/oss/oss-parameters.txt
1900 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1901 timeout > 0: seconds before rebooting
1902 timeout = 0: wait forever
1903 timeout < 0: reboot immediately
1906 parkbd.port= [HW] Parallel port number the keyboard adapter is
1907 connected to, default is 0.
1909 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1910 0 for XT, 1 for AT (default is AT).
1913 parport= [HW,PPT] Specify parallel ports. 0 disables.
1914 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1915 Use 'auto' to force the driver to use any
1916 IRQ/DMA settings detected (the default is to
1917 ignore detected IRQ/DMA settings because of
1918 possible conflicts). You can specify the base
1919 address, IRQ, and DMA settings; IRQ and DMA
1920 should be numbers, or 'auto' (for using detected
1921 settings on that particular port), or 'nofifo'
1922 (to avoid using a FIFO even if it is detected).
1923 Parallel ports are assigned in the order they
1924 are specified on the command line, starting
1927 parport_init_mode= [HW,PPT]
1928 Configure VIA parallel port to operate in
1929 a specific mode. This is necessary on Pegasos
1930 computer where firmware has no options for setting
1931 up parallel port mode and sets it to spp.
1932 Currently this function knows 686a and 8231 chips.
1933 Format: [spp|ps2|epp|ecp|ecpepp]
1936 Halt all CPUs after the first oops has been printed for
1937 the specified number of seconds. This is to be used if
1938 your oopses keep scrolling off the screen.
1943 See header of drivers/block/paride/pcd.c.
1944 See also Documentation/blockdev/paride.txt.
1946 pci=option[,option...] [PCI] various PCI subsystem options:
1947 earlydump [X86] dump PCI config space before the kernel
1949 off [X86] don't probe for the PCI bus
1950 bios [X86-32] force use of PCI BIOS, don't access
1951 the hardware directly. Use this if your machine
1952 has a non-standard PCI host bridge.
1953 nobios [X86-32] disallow use of PCI BIOS, only direct
1954 hardware access methods are allowed. Use this
1955 if you experience crashes upon bootup and you
1956 suspect they are caused by the BIOS.
1957 conf1 [X86] Force use of PCI Configuration
1959 conf2 [X86] Force use of PCI Configuration
1961 noaer [PCIE] If the PCIEAER kernel config parameter is
1962 enabled, this kernel boot option can be used to
1963 disable the use of PCIE advanced error reporting.
1964 nodomains [PCI] Disable support for multiple PCI
1965 root domains (aka PCI segments, in ACPI-speak).
1966 nommconf [X86] Disable use of MMCONFIG for PCI
1968 check_enable_amd_mmconf [X86] check for and enable
1969 properly configured MMIO access to PCI
1970 config space on AMD family 10h CPU
1971 nomsi [MSI] If the PCI_MSI kernel config parameter is
1972 enabled, this kernel boot option can be used to
1973 disable the use of MSI interrupts system-wide.
1974 noioapicquirk [APIC] Disable all boot interrupt quirks.
1975 Safety option to keep boot IRQs enabled. This
1976 should never be necessary.
1977 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1978 primary IO-APIC for bridges that cannot disable
1979 boot IRQs. This fixes a source of spurious IRQs
1980 when the system masks IRQs.
1981 noioapicreroute [APIC] Disable workaround that uses the
1982 boot IRQ equivalent of an IRQ that connects to
1983 a chipset where boot IRQs cannot be disabled.
1984 The opposite of ioapicreroute.
1985 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1986 routing table. These calls are known to be buggy
1987 on several machines and they hang the machine
1988 when used, but on other computers it's the only
1989 way to get the interrupt routing table. Try
1990 this option if the kernel is unable to allocate
1991 IRQs or discover secondary PCI buses on your
1993 rom [X86] Assign address space to expansion ROMs.
1994 Use with caution as certain devices share
1995 address decoders between ROMs and other
1997 norom [X86] Do not assign address space to
1998 expansion ROMs that do not already have
1999 BIOS assigned address ranges.
2000 nobar [X86] Do not assign address space to the
2001 BARs that weren't assigned by the BIOS.
2002 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2003 assigned automatically to PCI devices. You can
2004 make the kernel exclude IRQs of your ISA cards
2006 pirqaddr=0xAAAAA [X86] Specify the physical address
2007 of the PIRQ table (normally generated
2008 by the BIOS) if it is outside the
2009 F0000h-100000h range.
2010 lastbus=N [X86] Scan all buses thru bus #N. Can be
2011 useful if the kernel is unable to find your
2012 secondary buses and you want to tell it
2013 explicitly which ones they are.
2014 assign-busses [X86] Always assign all PCI bus
2015 numbers ourselves, overriding
2016 whatever the firmware may have done.
2017 usepirqmask [X86] Honor the possible IRQ mask stored
2018 in the BIOS $PIR table. This is needed on
2019 some systems with broken BIOSes, notably
2020 some HP Pavilion N5400 and Omnibook XE3
2021 notebooks. This will have no effect if ACPI
2022 IRQ routing is enabled.
2023 noacpi [X86] Do not use ACPI for IRQ routing
2024 or for PCI scanning.
2025 use_crs [X86] Use PCI host bridge window information
2026 from ACPI. On BIOSes from 2008 or later, this
2027 is enabled by default. If you need to use this,
2028 please report a bug.
2029 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2030 If you need to use this, please report a bug.
2031 routeirq Do IRQ routing for all PCI devices.
2032 This is normally done in pci_enable_device(),
2033 so this option is a temporary workaround
2034 for broken drivers that don't call it.
2035 skip_isa_align [X86] do not align io start addr, so can
2036 handle more pci cards
2037 firmware [ARM] Do not re-enumerate the bus but instead
2038 just use the configuration from the
2039 bootloader. This is currently used on
2040 IXP2000 systems where the bus has to be
2041 configured a certain way for adjunct CPUs.
2042 noearly [X86] Don't do any early type 1 scanning.
2043 This might help on some broken boards which
2044 machine check when some devices' config space
2045 is read. But various workarounds are disabled
2046 and some IOMMU drivers will not work.
2047 bfsort Sort PCI devices into breadth-first order.
2048 This sorting is done to get a device
2049 order compatible with older (<= 2.4) kernels.
2050 nobfsort Don't sort PCI devices into breadth-first order.
2051 cbiosize=nn[KMG] The fixed amount of bus space which is
2052 reserved for the CardBus bridge's IO window.
2053 The default value is 256 bytes.
2054 cbmemsize=nn[KMG] The fixed amount of bus space which is
2055 reserved for the CardBus bridge's memory
2056 window. The default value is 64 megabytes.
2059 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2060 Specifies alignment and device to reassign
2061 aligned memory resources.
2062 If <order of align> is not specified,
2063 PAGE_SIZE is used as alignment.
2064 PCI-PCI bridge can be specified, if resource
2065 windows need to be expanded.
2066 ecrc= Enable/disable PCIe ECRC (transaction layer
2067 end-to-end CRC checking).
2068 bios: Use BIOS/firmware settings. This is the
2072 realloc reallocate PCI resources if allocations done by BIOS
2075 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2078 force Enable ASPM even on devices that claim not to support it.
2079 WARNING: Forcing ASPM on may cause system lockups.
2081 pcie_ports= [PCIE] PCIe ports handling:
2082 auto Ask the BIOS whether or not to use native PCIe services
2083 associated with PCIe ports (PME, hot-plug, AER). Use
2084 them only if that is allowed by the BIOS.
2085 native Use native PCIe services associated with PCIe ports
2087 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2090 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2091 nomsi Do not use MSI for native PCIe PME signaling (this makes
2092 all PCIe root ports use INTx for all services).
2094 pcmv= [HW,PCMCIA] BadgePAD 4
2097 See Documentation/blockdev/paride.txt.
2099 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2102 See arch/parisc/kernel/pdc_chassis.c
2104 percpu_alloc= Select which percpu first chunk allocator to use.
2105 Currently supported values are "embed" and "page".
2106 Archs may support subset or none of the selections.
2107 See comments in mm/percpu.c for details on each
2108 allocator. This parameter is primarily for debugging
2109 and performance comparison.
2112 See Documentation/blockdev/paride.txt.
2115 See Documentation/blockdev/paride.txt.
2117 pirq= [SMP,APIC] Manual mp-table setup
2118 See Documentation/x86/i386/IO-APIC.txt.
2120 plip= [PPT,NET] Parallel port network link
2121 Format: { parport<nr> | timid | 0 }
2122 See also Documentation/parport.txt.
2124 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2125 Override pmtimer IOPort with a hex value.
2129 Enable PNP debug messages (depends on the
2130 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2131 via /sys/module/pnp/parameters/debug. We always show
2132 current resource usage; turning this on also shows
2133 possible settings and some assignment information.
2139 { on | off | curr | res | no-curr | no-res }
2142 [ISAPNP] Exclude IRQs for the autoconfiguration
2145 [ISAPNP] Exclude DMAs for the autoconfiguration
2147 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2148 Ranges are in pairs (I/O port base and size).
2151 [ISAPNP] Exclude memory regions for the
2153 Ranges are in pairs (memory base and size).
2155 ports= [IP_VS_FTP] IPVS ftp helper module
2157 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2159 Format: <port>,<port>....
2161 print-fatal-signals=
2162 [KNL] debug: print fatal signals
2164 If enabled, warn about various signal handling
2165 related application anomalies: too many signals,
2166 too many POSIX.1 timers, fatal signals causing a
2169 If you hit the warning due to signal overflow,
2170 you might want to try "ulimit -i unlimited".
2174 printk.time= Show timing data prefixed to each printk message line
2175 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2177 processor.max_cstate= [HW,ACPI]
2178 Limit processor to maximum C-state
2179 max_cstate=9 overrides any DMI blacklist limit.
2181 processor.nocst [HW,ACPI]
2182 Ignore the _CST method to determine C-states,
2183 instead using the legacy FADT method
2185 profile= [KNL] Enable kernel profiling via /proc/profile
2186 Format: [schedule,]<number>
2187 Param: "schedule" - profile schedule points.
2188 Param: <number> - step/bucket size as a power of 2 for
2189 statistical time based profiling.
2190 Param: "sleep" - profile D-state sleeping (millisecs).
2191 Requires CONFIG_SCHEDSTATS
2192 Param: "kvm" - profile VM exits.
2194 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2196 See Documentation/blockdev/ramdisk.txt.
2198 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2199 probe for; one of (bare|imps|exps|lifebook|any).
2200 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2202 psmouse.resetafter= [HW,MOUSE]
2203 Try to reset the device after so many bad packets
2206 [HW,MOUSE] Set desired mouse resolution, in dpi.
2207 psmouse.smartscroll=
2208 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2209 0 = disabled, 1 = enabled (default).
2211 pstore.backend= Specify the name of the pstore backend to use
2214 See Documentation/blockdev/paride.txt.
2217 [KNL] Number of legacy pty's. Overwrites compiled-in
2220 quiet [KNL] Disable most log messages
2225 See Documentation/md.txt.
2227 ramdisk_blocksize= [RAM]
2228 See Documentation/blockdev/ramdisk.txt.
2230 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2231 See Documentation/blockdev/ramdisk.txt.
2233 rcupdate.blimit= [KNL,BOOT]
2234 Set maximum number of finished RCU callbacks to process
2237 rcupdate.qhimark= [KNL,BOOT]
2238 Set threshold of queued
2239 RCU callbacks over which batch limiting is disabled.
2241 rcupdate.qlowmark= [KNL,BOOT]
2242 Set threshold of queued RCU callbacks below which
2243 batch limiting is re-enabled.
2247 Run specified binary instead of /init from the ramdisk,
2248 used for early userspace startup. See initrd.
2250 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2251 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2252 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2255 [KNL, SMP] Set scheduler's default relax_domain_level.
2256 See Documentation/cgroups/cpusets.txt.
2258 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2260 reservetop= [X86-32]
2262 Reserves a hole at the top of the kernel virtual
2267 Set the amount of memory to reserve for BIOS at
2268 the bottom of the address space.
2270 reset_devices [KNL] Force drivers to reset the underlying device
2271 during initialization.
2274 Specify the partition device for software suspend
2276 resume_offset= [SWSUSP]
2277 Specify the offset from the beginning of the partition
2278 given by "resume=" at which the swap header is located,
2279 in <PAGE_SIZE> units (needed only for swap files).
2280 See Documentation/power/swsusp-and-swap-files.txt
2282 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2283 read the resume files
2285 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2286 Useful for devices that are detected asynchronously
2287 (e.g. USB and MMC devices).
2289 hibernate= [HIBERNATION]
2290 noresume Don't check if there's a hibernation image
2291 present during boot.
2292 nocompress Don't compress/decompress hibernation images.
2294 retain_initrd [RAM] Keep initrd memory after extraction
2296 rhash_entries= [KNL,NET]
2297 Set number of hash buckets for route cache
2299 riscom8= [HW,SERIAL]
2300 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2302 ro [KNL] Mount root device read-only on boot
2304 root= [KNL] Root filesystem
2305 See name_to_dev_t comment in init/do_mounts.c.
2307 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2308 mount the root filesystem
2310 rootflags= [KNL] Set root filesystem mount option string
2312 rootfstype= [KNL] Set root filesystem type
2314 rootwait [KNL] Wait (indefinitely) for root device to show up.
2315 Useful for devices that are detected asynchronously
2316 (e.g. USB and MMC devices).
2318 rw [KNL] Mount root device read-write on boot
2320 S [KNL] Run init in single mode
2323 See drivers/net/irda/sa1100_ir.c.
2325 sbni= [NET] Granch SBNI12 leased line adapter
2327 sched_debug [KNL] Enables verbose scheduler debug messages.
2329 security= [SECURITY] Choose a security module to enable at boot.
2330 If this boot parameter is not specified, only the first
2331 security module asking for security registration will be
2332 loaded. An invalid security module name will be treated
2333 as if no module has been chosen.
2335 selinux= [SELINUX] Disable or enable SELinux at boot time.
2336 Format: { "0" | "1" }
2337 See security/selinux/Kconfig help text.
2340 Default value is set via kernel config option.
2341 If enabled at boot time, /selinux/disable can be used
2342 later to disable prior to initial policy load.
2344 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2345 Format: { "0" | "1" }
2346 See security/apparmor/Kconfig help text
2349 Default value is set via kernel config option.
2351 serialnumber [BUGS=X86-32]
2354 Maximal number of shapers.
2356 show_msr= [x86] show boot-time MSR settings
2357 Format: { <integer> }
2358 Show boot-time (BIOS-initialized) MSR settings.
2359 The parameter means the number of CPUs to show,
2360 for example 1 means boot CPU only.
2367 slub_debug[=options[,slabs]] [MM, SLUB]
2368 Enabling slub_debug allows one to determine the
2369 culprit if slab objects become corrupted. Enabling
2370 slub_debug can create guard zones around objects and
2371 may poison objects when not in use. Also tracks the
2372 last alloc / free. For more information see
2373 Documentation/vm/slub.txt.
2375 slub_max_order= [MM, SLUB]
2376 Determines the maximum allowed order for slabs.
2377 A high setting may cause OOMs due to memory
2378 fragmentation. For more information see
2379 Documentation/vm/slub.txt.
2381 slub_min_objects= [MM, SLUB]
2382 The minimum number of objects per slab. SLUB will
2383 increase the slab order up to slub_max_order to
2384 generate a sufficiently large slab able to contain
2385 the number of objects indicated. The higher the number
2386 of objects the smaller the overhead of tracking slabs
2387 and the less frequently locks need to be acquired.
2388 For more information see Documentation/vm/slub.txt.
2390 slub_min_order= [MM, SLUB]
2391 Determines the mininum page order for slabs. Must be
2392 lower than slub_max_order.
2393 For more information see Documentation/vm/slub.txt.
2395 slub_nomerge [MM, SLUB]
2396 Disable merging of slabs with similar size. May be
2397 necessary if there is some reason to distinguish
2398 allocs to different slabs. Debug options disable
2399 merging on their own.
2400 For more information see Documentation/vm/slub.txt.
2403 Format: <io1>[,<io2>[,...,<io8>]]
2405 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2406 attempt to substitute SMP alternatives once at boot.
2408 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2409 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2410 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2411 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2412 smsc-ircc2.ircc_irq= [HW] IRQ line
2413 smsc-ircc2.ircc_dma= [HW] DMA channel
2414 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2415 0: Toshiba Satellite 1800 (GP data pin select)
2416 1: Fast pin select (default)
2420 [KNL] Should the soft-lockup detector generate panics.
2423 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2424 See Documentation/laptops/sonypi.txt
2426 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2427 See Documentation/serial/specialix.txt.
2429 spia_io_base= [HW,MTD]
2435 Enabled the stack tracer on boot up.
2439 Set the STI (builtin display/keyboard on the HP-PARISC
2440 machines) console (graphic card) which should be used
2441 as the initial boot-console.
2442 See also comment in drivers/video/console/sticore.c.
2445 See comment in drivers/video/console/sticore.c.
2448 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2450 sunrpc.min_resvport=
2451 sunrpc.max_resvport=
2453 SunRPC servers often require that client requests
2454 originate from a privileged port (i.e. a port in the
2455 range 0 < portnr < 1024).
2456 An administrator who wishes to reserve some of these
2457 ports for other uses may adjust the range that the
2458 kernel's sunrpc client considers to be privileged
2459 using these two parameters to set the minimum and
2460 maximum port values.
2464 Control how the NFS server code allocates CPUs to
2465 service thread pools. Depending on how many NICs
2466 you have and where their interrupts are bound, this
2467 option will affect which CPUs will do NFS serving.
2468 Note: this parameter cannot be changed while the
2469 NFS server is running.
2471 auto the server chooses an appropriate mode
2472 automatically using heuristics
2473 global a single global pool contains all CPUs
2474 percpu one pool for each CPU
2475 pernode one pool for each NUMA node (equivalent
2476 to global on non-NUMA machines)
2478 sunrpc.tcp_slot_table_entries=
2479 sunrpc.udp_slot_table_entries=
2481 Sets the upper limit on the number of simultaneous
2482 RPC calls that can be sent from the client to a
2483 server. Increasing these values may allow you to
2484 improve throughput, but will also increase the
2485 amount of memory reserved for use by the client.
2488 [KNL] Enable accounting of swap in memory resource
2489 controller if no parameter or 1 is given or disable
2490 it if 0 is given (See Documentation/cgroups/memory.txt)
2492 swiotlb= [IA-64] Number of I/O TLB slabs
2496 sysfs.deprecated=0|1 [KNL]
2497 Enable/disable old style sysfs layout for old udev
2498 on older distributions. When this option is enabled
2499 very new udev will not work anymore. When this option
2500 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2501 in older udev will not work anymore.
2502 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2503 the kernel configuration.
2505 sysrq_always_enabled
2507 Ignore sysrq setting - this boot parameter will
2508 neutralize any effect of /proc/sys/kernel/sysrq.
2509 Useful for debugging.
2513 test_suspend= [SUSPEND]
2514 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2515 standby suspend) as the system sleep state to briefly
2516 enter during system startup. The system is woken from
2517 this state using a wakeup-capable RTC alarm.
2519 thash_entries= [KNL,NET]
2520 Set number of hash buckets for TCP connection
2522 thermal.act= [HW,ACPI]
2523 -1: disable all active trip points in all thermal zones
2524 <degrees C>: override all lowest active trip points
2526 thermal.crt= [HW,ACPI]
2527 -1: disable all critical trip points in all thermal zones
2528 <degrees C>: override all critical trip points
2530 thermal.nocrt= [HW,ACPI]
2531 Set to disable actions on ACPI thermal zone
2532 critical and hot trip points.
2534 thermal.off= [HW,ACPI]
2535 1: disable ACPI thermal control
2537 thermal.psv= [HW,ACPI]
2538 -1: disable all passive trip points
2539 <degrees C>: override all passive trip points to this
2542 thermal.tzp= [HW,ACPI]
2543 Specify global default ACPI thermal zone polling rate
2544 <deci-seconds>: poll all this frequency
2545 0: no polling (default)
2548 Force threading of all interrupt handlers except those
2549 marked explicitely IRQF_NO_THREAD.
2553 Specify if the kernel should make use of the cpu
2554 topology information if the hardware supports this.
2555 The scheduler will make use of this information and
2556 e.g. base its process migration decisions on it.
2561 tpm_suspend_pcr=[HW,TPM]
2562 Format: integer pcr id
2563 Specify that at suspend time, the tpm driver
2564 should extend the specified pcr with zeros,
2565 as a workaround for some chips which fail to
2566 flush the last written pcr on TPM_SaveState.
2567 This will guarantee that all the other pcrs
2570 trace_buf_size=nn[KMG]
2571 [FTRACE] will set tracing buffer size.
2573 trace_event=[event-list]
2574 [FTRACE] Set and start specified trace events in order
2575 to facilitate early boot debugging.
2576 See also Documentation/trace/events.txt
2578 tsc= Disable clocksource stability checks for TSC.
2580 [x86] reliable: mark tsc clocksource as reliable, this
2581 disables clocksource verification at runtime, as well
2582 as the stability checks done at bootup. Used to enable
2583 high-resolution timer mode on older hardware, and in
2584 virtualized environment.
2585 [x86] noirqtime: Do not use TSC to do irq accounting.
2586 Used to run time disable IRQ_TIME_ACCOUNTING on any
2587 platforms where RDTSC is slow and this accounting
2590 turbografx.map[2|3]= [HW,JOY]
2591 TurboGraFX parallel port interface
2593 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2594 See also Documentation/input/joystick-parport.txt
2596 udbg-immortal [PPC] When debugging early kernel crashes that
2597 happen after console_init() and before a proper
2598 console driver takes over, this boot options might
2599 help "seeing" what's going on.
2601 uhash_entries= [KNL,NET]
2602 Set number of hash buckets for UDP/UDP-Lite connections
2605 [USB] Ignore overcurrent events (default N).
2606 Some badly-designed motherboards generate lots of
2607 bogus events, for ports that aren't wired to
2608 anything. Set this parameter to avoid log spamming.
2609 Note that genuine overcurrent events won't be
2613 [X86] Cause panic on unknown NMI.
2615 usbcore.authorized_default=
2616 [USB] Default USB device authorization:
2617 (default -1 = authorized except for wireless USB,
2618 0 = not authorized, 1 = authorized)
2620 usbcore.autosuspend=
2621 [USB] The autosuspend time delay (in seconds) used
2622 for newly-detected USB devices (default 2). This
2623 is the time required before an idle device will be
2624 autosuspended. Devices for which the delay is set
2625 to a negative value won't be autosuspended at all.
2627 usbcore.usbfs_snoop=
2628 [USB] Set to log all usbfs traffic (default 0 = off).
2630 usbcore.blinkenlights=
2631 [USB] Set to cycle leds on hubs (default 0 = off).
2633 usbcore.old_scheme_first=
2634 [USB] Start with the old device initialization
2635 scheme (default 0 = off).
2637 usbcore.usbfs_memory_mb=
2638 [USB] Memory limit (in MB) for buffers allocated by
2639 usbfs (default = 16, 0 = max = 2047).
2641 usbcore.use_both_schemes=
2642 [USB] Try the other device initialization scheme
2643 if the first one fails (default 1 = enabled).
2645 usbcore.initial_descriptor_timeout=
2646 [USB] Specifies timeout for the initial 64-byte
2647 USB_REQ_GET_DESCRIPTOR request in milliseconds
2648 (default 5000 = 5.0 seconds).
2651 [USBHID] The interval which mice are to be polled at.
2653 usb-storage.delay_use=
2654 [UMS] The delay in seconds before a new device is
2655 scanned for Logical Units (default 5).
2658 [UMS] A list of quirks entries to supplement or
2659 override the built-in unusual_devs list. List
2660 entries are separated by commas. Each entry has
2661 the form VID:PID:Flags where VID and PID are Vendor
2662 and Product ID values (4-digit hex numbers) and
2663 Flags is a set of characters, each corresponding
2664 to a common usb-storage quirk flag as follows:
2665 a = SANE_SENSE (collect more than 18 bytes
2667 b = BAD_SENSE (don't collect more than 18
2668 bytes of sense data);
2669 c = FIX_CAPACITY (decrease the reported
2670 device capacity by one sector);
2671 d = NO_READ_DISC_INFO (don't use
2672 READ_DISC_INFO command);
2673 e = NO_READ_CAPACITY_16 (don't use
2674 READ_CAPACITY_16 command);
2675 h = CAPACITY_HEURISTICS (decrease the
2676 reported device capacity by one
2677 sector if the number is odd);
2678 i = IGNORE_DEVICE (don't bind to this
2680 l = NOT_LOCKABLE (don't try to lock and
2681 unlock ejectable media);
2682 m = MAX_SECTORS_64 (don't transfer more
2683 than 64 sectors = 32 KB at a time);
2684 n = INITIAL_READ10 (force a retry of the
2685 initial READ(10) command);
2686 o = CAPACITY_OK (accept the capacity
2687 reported by the device);
2688 r = IGNORE_RESIDUE (the device reports
2689 bogus residue values);
2690 s = SINGLE_LUN (the device has only one
2692 w = NO_WP_DETECT (don't test whether the
2693 medium is write-protected).
2694 Example: quirks=0419:aaf5:rl,0421:0433:rc
2696 user_debug= [KNL,ARM]
2698 See arch/arm/Kconfig.debug help text.
2699 1 - undefined instruction events
2701 4 - invalid data aborts
2704 Example: user_debug=31
2707 [X86] Flags controlling user PTE allocations.
2709 nohigh = do not allocate PTE pages in
2710 HIGHMEM regardless of setting
2714 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2715 vdso=1: enable VDSO (default)
2716 vdso=0: disable VDSO mapping
2719 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2720 vdso32=1: enable 32-bit VDSO (default)
2721 vdso32=0: disable 32-bit VDSO mapping
2724 vector=percpu: enable percpu vector domain
2726 video= [FB] Frame buffer configuration
2727 See Documentation/fb/modedb.txt.
2729 vga= [BOOT,X86-32] Select a particular video mode
2730 See Documentation/x86/boot.txt and
2731 Documentation/svga.txt.
2732 Use vga=ask for menu.
2733 This is actually a boot loader parameter; the value is
2734 passed to the kernel using a special protocol.
2736 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2737 size of <nn>. This can be used to increase the
2738 minimum size (128MB on x86). It can also be used to
2739 decrease the size and leave more room for directly
2742 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2745 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2748 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2752 Controls the behavior of vsyscalls (i.e. calls to
2753 fixed addresses of 0xffffffffff600x00 from legacy
2754 code). Most statically-linked binaries and older
2755 versions of glibc use these calls. Because these
2756 functions are at fixed addresses, they make nice
2757 targets for exploits that can control RIP.
2759 emulate [default] Vsyscalls turn into traps and are
2760 emulated reasonably safely.
2762 native Vsyscalls are native syscall instructions.
2763 This is a little bit faster than trapping
2764 and makes a few dynamic recompilers work
2765 better than they would in emulation mode.
2766 It also makes exploits much easier to write.
2768 none Vsyscalls don't work at all. This makes
2769 them quite hard to use for exploits but
2770 might break your system.
2772 vt.cur_default= [VT] Default cursor shape.
2773 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2774 the parameters of the <Esc>[?A;B;Cc escape sequence;
2775 see VGA-softcursor.txt. Default: 2 = underline.
2777 vt.default_blu= [VT]
2778 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2779 Change the default blue palette of the console.
2780 This is a 16-member array composed of values
2783 vt.default_grn= [VT]
2784 Format: <green0>,<green1>,<green2>,...,<green15>
2785 Change the default green palette of the console.
2786 This is a 16-member array composed of values
2789 vt.default_red= [VT]
2790 Format: <red0>,<red1>,<red2>,...,<red15>
2791 Change the default red palette of the console.
2792 This is a 16-member array composed of values
2798 Set system-wide default UTF-8 mode for all tty's.
2799 Default is 1, i.e. UTF-8 mode is enabled for all
2800 newly opened terminals.
2802 vt.global_cursor_default=
2805 Set system-wide default for whether a cursor
2806 is shown on new VTs. Default is -1,
2807 i.e. cursors will be created by default unless
2808 overridden by individual drivers. 0 will hide
2809 cursors, 1 will display them.
2811 watchdog timers [HW,WDT] For information on watchdog timers,
2812 see Documentation/watchdog/watchdog-parameters.txt
2813 or other driver-specific files in the
2814 Documentation/watchdog/ directory.
2816 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2817 default x2apic cluster mode on platforms
2820 x86_mrst_timer= [X86-32,APBT]
2821 Choose timer option for x86 Moorestown MID platform.
2822 Two valid options are apbt timer only and lapic timer
2823 plus one apbt timer for broadcast timer.
2824 x86_mrst_timer=apbt_only | lapic_and_apbt
2826 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2827 xd_geo= See header of drivers/block/xd.c.
2829 xen_emul_unplug= [HW,X86,XEN]
2830 Unplug Xen emulated devices
2831 Format: [unplug0,][unplug1]
2832 ide-disks -- unplug primary master IDE devices
2833 aux-ide-disks -- unplug non-primary-master IDE devices
2834 nics -- unplug network devices
2835 all -- unplug all emulated devices (NICs and IDE disks)
2836 unnecessary -- unplugging emulated devices is
2837 unnecessary even if the host did not respond to
2839 never -- do not unplug even if version check succeeds
2841 xirc2ps_cs= [NET,PCMCIA]
2843 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2845 ______________________________________________________________________
2849 Add more DRM drivers.
projects / mirror_ubuntu-bionic-kernel.git / blob