4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 ARM ARM architecture is enabled.
44 AVR32 AVR32 architecture is enabled.
45 AX25 Appropriate AX.25 support is enabled.
46 BLACKFIN Blackfin architecture is enabled.
47 DRM Direct Rendering Management support is enabled.
48 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
49 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
50 EFI EFI Partitioning (GPT) is enabled
51 EIDE EIDE/ATAPI support is enabled.
52 EVM Extended Verification Module
53 FB The frame buffer device is enabled.
54 FTRACE Function tracing enabled.
55 GCOV GCOV profiling is enabled.
56 HW Appropriate hardware is enabled.
57 IA-64 IA-64 architecture is enabled.
58 IMA Integrity measurement architecture is enabled.
59 IOSCHED More than one I/O scheduler is enabled.
60 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
61 IPV6 IPv6 support is enabled.
62 ISAPNP ISA PnP code is enabled.
63 ISDN Appropriate ISDN support is enabled.
64 JOY Appropriate joystick support is enabled.
65 KGDB Kernel debugger support is enabled.
66 KVM Kernel Virtual Machine support is enabled.
67 LIBATA Libata driver is enabled
68 LP Printer support is enabled.
69 LOOP Loopback device support is enabled.
70 M68k M68k architecture is enabled.
71 These options have more detailed description inside of
72 Documentation/m68k/kernel-options.txt.
73 MCA MCA bus support is enabled.
74 MDA MDA console support is enabled.
75 MIPS MIPS architecture is enabled.
76 MOUSE Appropriate mouse support is enabled.
77 MSI Message Signaled Interrupts (PCI).
78 MTD MTD (Memory Technology Device) support is enabled.
79 NET Appropriate network support is enabled.
80 NUMA NUMA support is enabled.
81 NFS Appropriate NFS support is enabled.
82 OSS OSS sound support is enabled.
83 PV_OPS A paravirtualized kernel is enabled.
84 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
85 PARISC The PA-RISC architecture is enabled.
86 PCI PCI bus support is enabled.
87 PCIE PCI Express support is enabled.
88 PCMCIA The PCMCIA subsystem is enabled.
89 PNP Plug & Play support is enabled.
90 PPC PowerPC architecture is enabled.
91 PPT Parallel port support is enabled.
92 PS2 Appropriate PS/2 support is enabled.
93 RAM RAM disk support is enabled.
94 S390 S390 architecture is enabled.
95 SCSI Appropriate SCSI support is enabled.
96 A lot of drivers have their options described inside
97 the Documentation/scsi/ sub-directory.
98 SECURITY Different security models are enabled.
99 SELINUX SELinux support is enabled.
100 APPARMOR AppArmor support is enabled.
101 SERIAL Serial support is enabled.
102 SH SuperH architecture is enabled.
103 SMP The kernel is an SMP kernel.
104 SPARC Sparc architecture is enabled.
105 SWSUSP Software suspend (hibernation) is enabled.
106 SUSPEND System suspend states are enabled.
107 TPM TPM drivers are enabled.
108 TS Appropriate touchscreen support is enabled.
109 UMS USB Mass Storage support is enabled.
110 USB USB support is enabled.
111 USBHID USB Human Interface Device support is enabled.
112 V4L Video For Linux support is enabled.
113 VGA The VGA console has been enabled.
114 VT Virtual terminal support is enabled.
115 WDT Watchdog support is enabled.
116 XT IBM PC/XT MFM hard disk support is enabled.
117 X86-32 X86-32, aka i386 architecture is enabled.
118 X86-64 X86-64 architecture is enabled.
119 More X86-64 boot options can be found in
120 Documentation/x86/x86_64/boot-options.txt .
121 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
122 XEN Xen support is enabled
124 In addition, the following text indicates that the option:
126 BUGS= Relates to possible processor bugs on the said processor.
127 KNL Is a kernel start-up parameter.
128 BOOT Is a boot loader parameter.
130 Parameters denoted with BOOT are actually interpreted by the boot
131 loader, and have no meaning to the kernel directly.
132 Do not modify the syntax of boot loader parameters without extreme
133 need or coordination with <Documentation/x86/boot.txt>.
135 There are also arch-specific kernel-parameters not documented here.
136 See for example <Documentation/x86/x86_64/boot-options.txt>.
138 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139 a trailing = on the name of any parameter states that that parameter will
140 be entered as an environment variable, whereas its absence indicates that
141 it will appear as a kernel argument readable via /proc/cmdline by programs
142 running once the system is up.
144 The number of kernel parameters is not limited, but the length of the
145 complete command line (parameters including spaces etc.) is limited to
146 a fixed number of characters. This limit depends on the architecture
147 and is between 256 and 4096 characters. It is defined in the file
148 ./include/asm/setup.h as COMMAND_LINE_SIZE.
150 Finally, the [KMG] suffix is commonly described after a number of kernel
151 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153 bytes respectively. Such letter suffixes can also be entirely omitted.
157 Advanced Configuration and Power Interface
158 Format: { force | off | strict | noirq | rsdt }
159 force -- enable ACPI if default was off
160 off -- disable ACPI if default was on
161 noirq -- do not use ACPI for IRQ routing
162 strict -- Be less tolerant of platforms that are not
163 strictly ACPI specification compliant.
164 rsdt -- prefer RSDT over (default) XSDT
165 copy_dsdt -- copy DSDT to memory
167 See also Documentation/power/runtime_pm.txt, pci=noacpi
169 acpi_rsdp= [ACPI,EFI,KEXEC]
170 Pass the RSDP address to the kernel, mostly used
171 on machines running EFI runtime service to boot the
172 second kernel for kdump.
174 acpi_apic_instance= [ACPI, IOAPIC]
176 2: use 2nd APIC table, if available
177 1,0: use 1st APIC table
180 acpi_backlight= [HW,ACPI]
181 acpi_backlight=vendor
183 If set to vendor, prefer vendor specific driver
184 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
185 of the ACPI video.ko driver.
187 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
188 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
190 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191 debug output. Bits in debug_layer correspond to a
192 _COMPONENT in an ACPI source file, e.g.,
193 #define _COMPONENT ACPI_PCI_COMPONENT
194 Bits in debug_level correspond to a level in
195 ACPI_DEBUG_PRINT statements, e.g.,
196 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
197 The debug_level mask defaults to "info". See
198 Documentation/acpi/debug.txt for more information about
199 debug layers and levels.
201 Enable processor driver info messages:
202 acpi.debug_layer=0x20000000
203 Enable PCI/PCI interrupt routing info messages:
204 acpi.debug_layer=0x400000
205 Enable AML "Debug" output, i.e., stores to the Debug
206 object while interpreting AML:
207 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
208 Enable all messages related to ACPI hardware:
209 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
211 Some values produce so much output that the system is
212 unusable. The "log_buf_len" parameter may be useful
213 if you need to capture more output.
215 acpi_irq_balance [HW,ACPI]
216 ACPI will balance active IRQs
219 acpi_irq_nobalance [HW,ACPI]
220 ACPI will not move active IRQs (default)
223 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224 Format: <irq>,<irq>...
226 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
228 Format: <irq>,<irq>...
230 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
232 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
233 Format: To spoof as Windows 98: ="Microsoft Windows"
235 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
236 acpi_osi="string1" # add string1 -- only one string
237 acpi_osi="!string2" # remove built-in string2
238 acpi_osi= # disable all strings
241 Override the pmtimer bug detection: force the kernel
242 to assume that this machine's pmtimer latches its value
243 and always returns good values.
245 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
246 Format: { level | edge | high | low }
248 acpi_serialize [HW,ACPI] force serialization of AML methods
250 acpi_skip_timer_override [HW,ACPI]
251 Recognize and ignore IRQ0/pin2 Interrupt Override.
252 For broken nForce2 BIOS resulting in XT-PIC timer.
254 acpi_sleep= [HW,ACPI] Sleep options
255 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
256 old_ordering, nonvs, sci_force_enable }
257 See Documentation/power/video.txt for information on
259 s3_beep is for debugging; it makes the PC's speaker beep
260 as soon as the kernel's real-mode entry point is called.
261 s4_nohwsig prevents ACPI hardware signature from being
262 used during resume from hibernation.
263 old_ordering causes the ACPI 1.0 ordering of the _PTS
264 control method, with respect to putting devices into
265 low power states, to be enforced (the ACPI 2.0 ordering
266 of _PTS is used by default).
267 nonvs prevents the kernel from saving/restoring the
268 ACPI NVS memory during suspend/hibernation and resume.
269 sci_force_enable causes the kernel to set SCI_EN directly
270 on resume from S1/S3 (which is against the ACPI spec,
271 but some broken systems don't work without it).
273 acpi_use_timer_override [HW,ACPI]
274 Use timer override. For some broken Nvidia NF5 boards
275 that require a timer override, but don't have HPET
277 acpi_enforce_resources= [ACPI]
278 { strict | lax | no }
279 Check for resource conflicts between native drivers
280 and ACPI OperationRegions (SystemIO and SystemMemory
281 only). IO ports and memory declared in ACPI might be
282 used by the ACPI subsystem in arbitrary AML code and
283 can interfere with legacy drivers.
284 strict (default): access to resources claimed by ACPI
285 is denied; legacy drivers trying to access reserved
286 resources will fail to bind to device using them.
287 lax: access to resources claimed by ACPI is allowed;
288 legacy drivers trying to access reserved resources
289 will bind successfully but a warning message is logged.
290 no: ACPI OperationRegions are not marked as reserved,
291 no further checks are performed.
293 add_efi_memmap [EFI; X86] Include EFI memory map in
294 kernel's map of available physical RAM.
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
303 See Documentation/sound/alsa/alsa-parameters.txt
306 Allow the default userspace alignment fault handler
307 behaviour to be specified. Bit 0 enables warnings,
308 bit 1 enables fixups, and bit 2 sends a segfault.
310 align_va_addr= [X86-64]
311 Align virtual addresses by clearing slice [14:12] when
312 allocating a VMA at process creation time. This option
313 gives you up to 3% performance improvement on AMD F15h
314 machines (where it is enabled by default) for a
315 CPU-intensive style benchmark, and it can vary highly in
316 a microbenchmark depending on workload and compiler.
318 32: only for 32-bit processes
319 64: only for 64-bit processes
320 on: enable for both 32- and 64-bit processes
321 off: disable for both 32- and 64-bit processes
323 amd_iommu= [HW,X86-64]
324 Pass parameters to the AMD IOMMU driver in the system.
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
330 off - do not initialize any AMD IOMMU found in
333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
336 See also Documentation/input/joystick.txt
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
344 Power management functions (SPARCstation-4/5 + deriv.)
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
351 Change the output verbosity whilst booting
352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
357 See Documentation/networking/ipv6.txt.
359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
368 apm= [APM] Advanced Power Management
369 See header of arch/x86/kernel/apm_32.c.
371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
376 atarimouse= [HW,MOUSE] Atari Mouse
378 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
379 EzKey and similar keyboards
381 atkbd.reset= [HW] Reset keyboard during initialization
383 atkbd.set= [HW] Select keyboard code set
384 Format: <int> (2 = AT (default), 3 = PS/2)
386 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 atkbd.softraw= [HW] Choose between synthetic and real raw mode
390 Format: <bool> (0 = real, 1 = synthetic (default))
392 atkbd.softrepeat= [HW]
393 Use software keyboard repeat
397 baycom_epp= [HW,AX25]
400 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
402 See header of drivers/net/hamradio/baycom_par.c.
404 baycom_ser_fdx= [HW,AX25]
405 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
406 Format: <io>,<irq>,<mode>[,<baud>]
407 See header of drivers/net/hamradio/baycom_ser_fdx.c.
409 baycom_ser_hdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
411 Format: <io>,<irq>,<mode>
412 See header of drivers/net/hamradio/baycom_ser_hdx.c.
414 boot_delay= Milliseconds to delay each printk during boot.
415 Values larger than 10 seconds (10000) are changed to
419 bootmem_debug [KNL] Enable bootmem allocator debug messages.
421 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
422 bttv.radio= Most important insmod options are available as
424 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bulk_remove=off [PPC] This parameter disables the use of the pSeries
428 firmware feature for flushing multiple hpte entries
431 c101= [NET] Moxa C101 synchronous serial card
433 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
434 Sometimes CPU hardware bugs make them report the cache
435 size incorrectly. The kernel will attempt work arounds
436 to fix known problems, but for some CPUs it is not
437 possible to determine what the correct size should be.
438 This option provides an override for these situations.
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
460 Value can be changed at runtime via
461 /selinux/checkreqprot.
464 See Documentation/s390/CommonIO for details.
466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
468 Forces specified clocksource (if available) to be used
469 when calculating gettimeofday(). If specified
470 clocksource is not available, it defaults to PIT.
471 Format: { pit | tsc | cyclone | pmtmr }
473 clocksource= Override the default clocksource
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
479 [all] jiffies (this is the base, fallback clocksource)
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
484 [X86-32] pit,hpet,tsc;
485 scx200_hrt on Geode; cyclone on IBM x440
493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
495 arch/x86/include/asm/cpufeature.h for the valid bit
496 numbers. Note the Linux specific bits are not necessarily
497 stable over kernel options, but the vendor specific
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
507 Sets the size of kernel global memory area for contiguous
508 memory allocations. For more information, see
509 include/linux/dma-contiguous.h
511 cmo_free_hint= [PPC] Format: { yes | no }
512 Specify whether pages are marked as being inactive
513 when they are freed. This is used in CMO environments
514 to determine OS memory pressure for page stealing by
518 coherent_pool=nn[KMG] [ARM,KNL]
519 Sets the size of memory pool for coherent, atomic dma
520 allocations, by default set to 256K.
522 code_bytes [X86] How many bytes of object code to print
527 com20020= [HW,NET] ARCnet - COM20020 chipset
529 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
531 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
535 ARCnet - COM90xx chipset (memory-mapped buffers)
536 Format: <io>[,<irq>[,<memstart>]]
538 condev= [HW,S390] console device
541 console= [KNL] Output console device and options.
543 tty<n> Use the virtual console device <n>.
547 Use the specified serial port. The options are of
548 the form "bbbbpnf", where "bbbb" is the baud rate,
549 "p" is parity ("n", "o", or "e"), "n" is number of
550 bits, and "f" is flow control ("r" for RTS or
551 omit it). Default is "9600n8".
553 See Documentation/serial-console.txt for more
555 Documentation/networking/netconsole.txt for an
558 uart[8250],io,<addr>[,options]
559 uart[8250],mmio,<addr>[,options]
560 Start an early, polled-mode console on the 8250/16550
561 UART at the specified I/O port or MMIO address,
562 switching to the matching ttyS device later. The
563 options are the same as for ttyS, above.
564 hvc<n> Use the hypervisor console device <n>. This is for
565 both Xen and PowerPC hypervisors.
567 If the device connected to the port is not a TTY but a braille
568 device, prepend "brl," before the device type, for instance
570 For now, only VisioBraille is supported.
572 consoleblank= [KNL] The console blank (screen saver) timeout in
573 seconds. Defaults to 10*60 = 10mins. A value of 0
574 disables the blank timer.
577 [KNL] Change the default value for
578 /proc/<pid>/coredump_filter.
579 See also Documentation/filesystems/proc.txt.
581 cpuidle.off=1 [CPU_IDLE]
582 disable the cpuidle sub-system
584 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
586 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
588 crashkernel=size[KMG][@offset[KMG]]
589 [KNL] Using kexec, Linux can switch to a 'crash kernel'
590 upon panic. This parameter reserves the physical
591 memory region [offset, offset + size] for that kernel
592 image. If '@offset' is omitted, then a suitable offset
593 is selected automatically. Check
594 Documentation/kdump/kdump.txt for further details.
596 crashkernel=range1:size1[,range2:size2,...][@offset]
597 [KNL] Same as above, but depends on the memory
598 in the running system. The syntax of range is
599 start-[end] where start and end are both
600 a memory unit (amount[KMG]). See also
601 Documentation/kdump/kdump.txt for an example.
606 cs89x0_media= [HW,NET]
607 Format: { rj45 | aui | bnc }
610 See header of drivers/s390/block/dasd_devmap.c.
612 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
613 (one device per port)
614 Format: <port#>,<type>
615 See also Documentation/input/joystick-parport.txt
617 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
618 time. See Documentation/dynamic-debug-howto.txt for
621 debug [KNL] Enable kernel debugging (events log level).
624 [KNL] verbose self-tests
626 Print debugging info while doing the locking API
628 We default to 0 (no extra messages), setting it to
629 1 will print _a lot_ more information - normally
630 only useful to kernel developers.
632 debug_objects [KNL] Enable object debugging
635 [KNL] Disable object debugging
637 debug_guardpage_minorder=
638 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
639 parameter allows control of the order of pages that will
640 be intentionally kept free (and hence protected) by the
641 buddy allocator. Bigger value increase the probability
642 of catching random memory corruption, but reduce the
643 amount of memory for normal system use. The maximum
644 possible value is MAX_ORDER/2. Setting this parameter
645 to 1 or 2 should be enough to identify most random
646 memory corruption problems caused by bugs in kernel or
647 driver code when a CPU writes to (or reads from) a
648 random memory location. Note that there exists a class
649 of memory corruptions problems caused by buggy H/W or
650 F/W or by drivers badly programing DMA (basically when
651 memory is written at bus level and the CPU MMU is
652 bypassed) which are not detectable by
653 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
654 tracking down these problems.
656 debugpat [X86] Enable PAT debugging
658 decnet.addr= [HW,NET]
659 Format: <area>[,<node>]
660 See also Documentation/networking/decnet.txt.
663 [same as hugepagesz=] The size of the default
664 HugeTLB page size. This is the size represented by
665 the legacy /proc/ hugepages APIs, used for SHM, and
666 default size when mounting hugetlbfs filesystems.
667 Defaults to the default architecture's huge page size
671 Set number of hash buckets for dentry cache.
674 IO parameters + enable/disable command.
676 digiepca= [HW,SERIAL]
677 See drivers/char/README.epca and
678 Documentation/serial/digiepca.txt.
681 See Documentation/networking/ipv6.txt.
683 disable_ddw [PPC/PSERIES]
684 Disable Dynamic DMA Window support. Use this if
685 to workaround buggy firmware.
688 See Documentation/networking/ipv6.txt.
690 disable_mtrr_cleanup [X86]
691 The kernel tries to adjust MTRR layout from continuous
692 to discrete, to make X server driver able to add WB
693 entry later. This parameter disables that.
695 disable_mtrr_trim [X86, Intel and AMD only]
696 By default the kernel will trim any uncacheable
697 memory out of your available memory pool based on
698 MTRR settings. This parameter disables that behavior,
699 possibly causing your machine to run very slowly.
701 disable_timer_pin_1 [X86]
702 Disable PIN 1 of APIC timer
703 Can be useful to work around chipset bugs.
705 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
706 this option disables the debugging code at boot.
708 dma_debug_entries=<number>
709 This option allows to tune the number of preallocated
710 entries for DMA-API debugging code. One entry is
711 required per DMA-API allocation. Use this if the
712 DMA-API debugging code disables itself because the
713 architectural default is too low.
715 dma_debug_driver=<driver_name>
716 With this option the DMA-API debugging driver
717 filter feature can be enabled at boot time. Just
718 pass the driver to filter for as the parameter.
719 The filter can be disabled or changed to another
720 driver later using sysfs.
724 earlycon= [KNL] Output early console device and options.
725 uart[8250],io,<addr>[,options]
726 uart[8250],mmio,<addr>[,options]
727 uart[8250],mmio32,<addr>[,options]
728 Start an early, polled-mode console on the 8250/16550
729 UART at the specified I/O port or MMIO address.
730 MMIO inter-register address stride is either 8-bit
731 (mmio) or 32-bit (mmio32).
732 The options are the same as for ttyS, above.
734 earlyprintk= [X86,SH,BLACKFIN]
737 earlyprintk=serial[,ttySn[,baudrate]]
738 earlyprintk=ttySn[,baudrate]
739 earlyprintk=dbgp[debugController#]
741 Append ",keep" to not disable it when the real console
744 Only vga or serial or usb debug port at a time.
746 Currently only ttyS0 and ttyS1 are supported.
748 Interaction with the standard serial driver is not
751 The VGA output is eventually overwritten by the real
754 The xen output can only be used by Xen PV guests.
756 ekgdboc= [X86,KGDB] Allow early kernel console debugging
759 This is designed to be used in conjunction with
760 the boot argument: earlyprintk=vga
763 Format: {"off" | "on" | "skip[mbr]"}
765 efi_no_storage_paranoia [EFI; X86]
766 Using this parameter you can use more than 50% of
767 your efi variable storage. Use this parameter only if
768 you are really sure that your UEFI does sane gc and
769 fulfills the spec otherwise your board may brick.
771 eisa_irq_edge= [PARISC,HW]
772 See header of drivers/parisc/eisa.c.
775 See comment before function elanfreq_setup() in
776 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
779 Format: {"cfq" | "deadline" | "noop"}
780 See Documentation/block/cfq-iosched.txt and
781 Documentation/block/deadline-iosched.txt for details.
783 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
784 Specifies physical address of start of kernel core
785 image elf header and optionally the size. Generally
786 kexec loader will pass this option to capture kernel.
787 See Documentation/kdump/kdump.txt for details.
789 enable_mtrr_cleanup [X86]
790 The kernel tries to adjust MTRR layout from continuous
791 to discrete, to make X server driver able to add WB
792 entry later. This parameter enables that.
794 enable_timer_pin_1 [X86]
795 Enable PIN 1 of APIC timer
796 Can be useful to work around chipset bugs
797 (in particular on some ATI chipsets).
798 The kernel tries to set a reasonable default.
800 enforcing [SELINUX] Set initial enforcing status.
802 See security/selinux/Kconfig help text.
803 0 -- permissive (log only, no denials).
804 1 -- enforcing (deny and log).
806 Value can be changed at runtime via /selinux/enforce.
809 Disable Error Record Serialization Table (ERST)
812 ether= [HW,NET] Ethernet cards parameters
813 This option is obsoleted by the "netdev=" option, which
814 has equivalent usage. See its documentation for details.
818 Permit 'security.evm' to be updated regardless of
819 current integrity status.
823 fail_make_request=[KNL]
824 General fault injection mechanism.
825 Format: <interval>,<probability>,<space>,<times>
826 See also Documentation/fault-injection/.
829 See Documentation/blockdev/floppy.txt.
831 force_pal_cache_flush
832 [IA-64] Avoid check_sal_cache_flush which may hang on
833 buggy SAL_CACHE_FLUSH implementations. Using this
834 parameter will force ia64_sal_cache_flush to call
835 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
838 [FTRACE] will set and start the specified tracer
839 as early as possible in order to facilitate early
842 ftrace_dump_on_oops[=orig_cpu]
843 [FTRACE] will dump the trace buffers on oops.
844 If no parameter is passed, ftrace will dump
845 buffers of all CPUs, but if you pass orig_cpu, it will
846 dump only the buffer of the CPU that triggered the
849 ftrace_filter=[function-list]
850 [FTRACE] Limit the functions traced by the function
851 tracer at boot up. function-list is a comma separated
852 list of functions. This list can be changed at run
853 time by the set_ftrace_filter file in the debugfs
856 ftrace_notrace=[function-list]
857 [FTRACE] Do not trace the functions specified in
858 function-list. This list can be changed at run time
859 by the set_ftrace_notrace file in the debugfs
862 ftrace_graph_filter=[function-list]
863 [FTRACE] Limit the top level callers functions traced
864 by the function graph tracer at boot up.
865 function-list is a comma separated list of functions
866 that can be changed at run time by the
867 set_graph_function file in the debugfs tracing directory.
870 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
871 support via parallel port (up to 5 devices per port)
872 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
873 See also Documentation/input/joystick-parport.txt
877 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
881 gcov_persist= [GCOV] When non-zero (default), profiling data for
882 kernel modules is saved and remains accessible via
883 debugfs, even when the module is unloaded/reloaded.
884 When zero, profiling data is discarded and associated
885 debugfs files are removed at module unload time.
887 gpt [EFI] Forces disk with valid GPT signature but
888 invalid Protective MBR to be treated as GPT.
890 hashdist= [KNL,NUMA] Large hashes allocated during boot
891 are distributed across NUMA nodes. Defaults on
892 for 64-bit NUMA, off otherwise.
893 Format: 0 | 1 (for off | on)
895 hcl= [IA-64] SGI's Hardware Graph compatibility layer
897 hd= [EIDE] (E)IDE hard drive subsystem geometry
898 Format: <cyl>,<head>,<sect>
901 Disable Hardware Error Source Table (HEST) support;
902 corresponding firmware-first mode error processing
903 logic will be disabled.
905 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
906 size of <nn>. This works even on boxes that have no
907 highmem otherwise. This also works to reduce highmem
908 size on bigger boxes.
910 highres= [KNL] Enable/disable high resolution timer mode.
911 Valid parameters: "on", "off"
915 See Documentation/isdn/README.HiSax.
919 hpet= [X86-32,HPET] option to control HPET usage
920 Format: { enable (default) | disable | force |
922 disable: disable HPET and use PIT instead
923 force: allow force enabled of undocumented chips (ICH4,
925 verbose: show contents of HPET registers during setup
927 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
928 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
929 On x86-64 and powerpc, this option can be specified
930 multiple times interleaved with hugepages= to reserve
931 huge pages of different sizes. Valid pages sizes on
932 x86-64 are 2M (when the CPU supports "pse") and 1G
933 (when the CPU supports the "pdpe1gb" cpuinfo flag)
934 Note that 1GB pages can only be allocated at boot time
935 using hugepages= and not freed afterwards.
937 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
938 terminal devices. Valid values: 0..8
939 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
940 If specified, z/VM IUCV HVC accepts connections
941 from listed z/VM user IDs only.
944 Do not unregister boot console at start. This is only
945 useful for debugging when something happens in the window
946 between unregistering the boot console and initializing
949 i2c_bus= [HW] Override the default board specific I2C bus speed
950 or register an additional I2C bus that is not
951 registered from board initialization code.
955 i8042.debug [HW] Toggle i8042 debug mode
956 i8042.direct [HW] Put keyboard port into non-translated mode
957 i8042.dumbkbd [HW] Pretend that controller can only read data from
958 keyboard and cannot control its state
959 (Don't attempt to blink the leds)
960 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
961 i8042.nokbd [HW] Don't check/create keyboard port
962 i8042.noloop [HW] Disable the AUX Loopback command while probing
964 i8042.nomux [HW] Don't check presence of an active multiplexing
966 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
968 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
969 i8042.reset [HW] Reset the controller during init and cleanup
970 i8042.unlock [HW] Unlock (ignore) the keylock
971 i8042.kbdreset [HW] Reset device connected to KBD port
975 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
976 indicates that the driver is running on unsupported
978 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
979 does not match list of supported models.
981 [HW] Report power status in /proc/i8k
982 (disabled by default)
983 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
986 i915.invert_brightness=
987 [DRM] Invert the sense of the variable that is used to
988 set the brightness of the panel backlight. Normally a
989 brightness value of 0 indicates backlight switched off,
990 and the maximum of the brightness value sets the backlight
991 to maximum brightness. If this parameter is set to 0
992 (default) and the machine requires it, or this parameter
993 is set to 1, a brightness value of 0 sets the backlight
994 to maximum brightness, and the maximum of the brightness
995 value switches the backlight off.
996 -1 -- never invert brightness
998 1 -- force brightness inversion
1001 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1003 ide-core.nodma= [HW] (E)IDE subsystem
1004 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1005 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1006 .cdrom .chs .ignore_cable are additional options
1007 See Documentation/ide/ide.txt.
1009 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1010 Claim all unknown PCI IDE storage controllers.
1013 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
1014 Poll forces a polling idle loop that can slightly
1015 improve the performance of waking up a idle CPU, but
1016 will use a lot of power and make the system run hot.
1018 idle=mwait: On systems which support MONITOR/MWAIT but
1019 the kernel chose to not use it because it doesn't save
1020 as much power as a normal idle loop, use the
1021 MONITOR/MWAIT idle loop anyways. Performance should be
1022 the same as idle=poll.
1023 idle=halt: Halt is forced to be used for CPU idle.
1024 In such case C2/C3 won't be used again.
1025 idle=nomwait: Disable mwait for CPU C-states
1027 ignore_loglevel [KNL]
1028 Ignore loglevel setting - this will print /all/
1029 kernel messages to the console. Useful for debugging.
1030 We also add it as printk module parameter, so users
1031 could change it dynamically, usually by
1032 /sys/module/printk/parameters/ignore_loglevel.
1034 ihash_entries= [KNL]
1035 Set number of hash buckets for inode cache.
1038 Format: { "0" | "1" }
1039 0 -- integrity auditing messages. (Default)
1040 1 -- enable informational integrity auditing messages.
1043 Format: { "sha1" | "md5" }
1047 Load a policy which meets the needs of the Trusted
1048 Computing Base. This means IMA will measure all
1049 programs exec'd, files mmap'd for exec, and all files
1050 opened for read by uid=0.
1054 Run specified binary instead of /sbin/init as init
1057 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1058 for working out where the kernel is dying during
1061 initrd= [BOOT] Specify the location of the initial ramdisk
1063 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1066 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1068 Enable intel iommu driver.
1070 Disable intel iommu driver.
1071 igfx_off [Default Off]
1072 By default, gfx is mapped as normal device. If a gfx
1073 device has a dedicated DMAR unit, the DMAR unit is
1074 bypassed by not enabling DMAR with this option. In
1075 this case, gfx device will use physical address for
1078 With this option iommu will not optimize to look
1079 for io virtual address below 32-bit forcing dual
1080 address cycle on pci bus for cards supporting greater
1081 than 32-bit addressing. The default is to look
1082 for translation below 32-bit and if not available
1083 then look in the higher range.
1084 strict [Default Off]
1085 With this option on every unmap_single operation will
1086 result in a hardware IOTLB flush operation as opposed
1087 to batching them for performance.
1088 sp_off [Default Off]
1089 By default, super page will be supported if Intel IOMMU
1090 has the capability. With this option, super page will
1092 intremap= [X86-64, Intel-IOMMU]
1093 on enable Interrupt Remapping (default)
1094 off disable Interrupt Remapping
1095 nosid disable Source ID checking
1097 BIOS x2APIC opt-out request will be ignored
1101 iomem= Disable strict checking of access to MMIO memory
1102 strict regions from userspace.
1118 io7= [HW] IO7 for Marvel based alpha systems
1119 See comment before marvel_specify_io7 in
1120 arch/alpha/kernel/core_marvel.c.
1122 io_delay= [X86] I/O delay method
1124 Standard port 0x80 based delay
1126 Alternate port 0xed based delay (needed on some systems)
1128 Simple two microseconds delay
1133 See Documentation/filesystems/nfs/nfsroot.txt.
1135 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1136 See comment before ip2_setup() in
1137 drivers/char/ip2/ip2base.c.
1140 When an interrupt is not handled search all handlers
1141 for it. Intended to get systems with badly broken
1145 When an interrupt is not handled search all handlers
1146 for it. Also check all handlers each timer
1147 interrupt. Intended to get systems with badly broken
1151 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1153 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1155 <cpu number>,...,<cpu number>
1157 <cpu number>-<cpu number>
1158 (must be a positive range in ascending order)
1160 <cpu number>,...,<cpu number>-<cpu number>
1162 This option can be used to specify one or more CPUs
1163 to isolate from the general SMP balancing and scheduling
1164 algorithms. You can move a process onto or off an
1165 "isolated" CPU via the CPU affinity syscalls or cpuset.
1166 <cpu number> begins at 0 and the maximum value is
1167 "number of CPUs in system - 1".
1169 This option is the preferred way to isolate CPUs. The
1170 alternative -- manually setting the CPU mask of all
1171 tasks in the system -- can cause problems and
1172 suboptimal load balancer performance.
1176 js= [HW,JOY] Analog joystick
1177 See Documentation/input/joystick.txt.
1181 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1182 specifies the amount of memory usable by the kernel
1183 for non-movable allocations. The requested amount is
1184 spread evenly throughout all nodes in the system. The
1185 remaining memory in each node is used for Movable
1186 pages. In the event, a node is too small to have both
1187 kernelcore and Movable pages, kernelcore pages will
1188 take priority and other nodes will have a larger number
1189 of kernelcore pages. The Movable zone is used for the
1190 allocation of pages that may be reclaimed or moved
1191 by the page migration subsystem. This means that
1192 HugeTLB pages may not be allocated from this zone.
1193 Note that allocations like PTEs-from-HighMem still
1194 use the HighMem zone if it exists, and the Normal
1195 zone if it does not.
1197 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1198 Format: <Controller#>[,poll interval]
1199 The controller # is the number of the ehci usb debug
1200 port as it is probed via PCI. The poll interval is
1201 optional and is the number seconds in between
1202 each poll cycle to the debug port in case you need
1203 the functionality for interrupting the kernel with
1204 gdb or control-c on the dbgp connection. When
1205 not using this parameter you use sysrq-g to break into
1206 the kernel debugger.
1208 kgdboc= [KGDB,HW] kgdb over consoles.
1209 Requires a tty driver that supports console polling,
1210 or a supported polling keyboard driver (non-usb).
1211 Serial only format: <serial_device>[,baud]
1212 keyboard only format: kbd
1213 keyboard and serial format: kbd,<serial_device>[,baud]
1214 Optional Kernel mode setting:
1215 kms, kbd format: kms,kbd
1216 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1218 kgdbwait [KGDB] Stop kernel execution and enter the
1219 kernel debugger at the earliest opportunity.
1221 kmac= [MIPS] korina ethernet MAC address.
1222 Configure the RouterBoard 532 series on-chip
1223 Ethernet adapter MAC address.
1225 kmemleak= [KNL] Boot-time kmemleak enable/disable
1226 Valid arguments: on, off
1229 kstack=N [X86] Print N words from the kernel stack
1232 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1233 Default is 0 (don't ignore, but inject #GP)
1235 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1236 Default is 1 (enabled)
1238 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1242 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1243 Default is 1 (enabled)
1245 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1247 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1249 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1250 (virtualized MMU) support on capable Intel chips.
1251 Default is 1 (enabled)
1253 kvm-intel.emulate_invalid_guest_state=
1254 [KVM,Intel] Enable emulation of invalid guest states
1255 Default is 0 (disabled)
1257 kvm-intel.flexpriority=
1258 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1259 Default is 1 (enabled)
1262 [KVM,Intel] Enable VMX nesting (nVMX).
1263 Default is 0 (disabled)
1265 kvm-intel.unrestricted_guest=
1266 [KVM,Intel] Disable unrestricted guest feature
1267 (virtualized real and unpaged mode) on capable
1268 Intel chips. Default is 1 (enabled)
1270 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1271 feature (tagged TLBs) on capable Intel chips.
1272 Default is 1 (enabled)
1278 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1281 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1284 libata.dma= [LIBATA] DMA control
1285 libata.dma=0 Disable all PATA and SATA DMA
1286 libata.dma=1 PATA and SATA Disk DMA only
1287 libata.dma=2 ATAPI (CDROM) DMA only
1288 libata.dma=4 Compact Flash DMA only
1289 Combinations also work, so libata.dma=3 enables DMA
1290 for disks and CDROMs, but not CFs.
1292 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1293 libata.ignore_hpa=0 keep BIOS limits (default)
1294 libata.ignore_hpa=1 ignore limits, using full disk
1296 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1300 libata.force= [LIBATA] Force configurations. The format is comma
1301 separated list of "[ID:]VAL" where ID is
1302 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1303 matching port, link or device. Basically, it matches
1304 the ATA ID string printed on console by libata. If
1305 the whole ID part is omitted, the last PORT and DEVICE
1306 values are used. If ID hasn't been specified yet, the
1307 configuration applies to all ports, links and devices.
1309 If only DEVICE is omitted, the parameter applies to
1310 the port and all links and devices behind it. DEVICE
1311 number of 0 either selects the first device or the
1312 first fan-out link behind PMP device. It does not
1313 select the host link. DEVICE number of 15 selects the
1314 host link and device attached to it.
1316 The VAL specifies the configuration to force. As long
1317 as there's no ambiguity shortcut notation is allowed.
1318 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1319 The following configurations can be forced.
1321 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1322 Any ID with matching PORT is used.
1324 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1326 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1327 udma[/][16,25,33,44,66,100,133] notation is also
1330 * [no]ncq: Turn on or off NCQ.
1332 * nohrst, nosrst, norst: suppress hard, soft
1335 * dump_id: dump IDENTIFY data.
1337 * disable: Disable this device.
1339 If there are multiple matching configurations changing
1340 the same attribute, the last one is used.
1342 memblock=debug [KNL] Enable memblock debug messages.
1344 load_ramdisk= [RAM] List of ramdisks to load from floppy
1345 See Documentation/blockdev/ramdisk.txt.
1347 lockd.nlm_grace_period=P [NFS] Assign grace period.
1350 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1353 lockd.nlm_timeout=T [NFS] Assign timeout value.
1356 lockd.nlm_udpport=M [NFS] Assign UDP port.
1359 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1362 loglevel= All Kernel Messages with a loglevel smaller than the
1363 console loglevel will be printed to the console. It can
1364 also be changed with klogd or other programs. The
1365 loglevels are defined as follows:
1367 0 (KERN_EMERG) system is unusable
1368 1 (KERN_ALERT) action must be taken immediately
1369 2 (KERN_CRIT) critical conditions
1370 3 (KERN_ERR) error conditions
1371 4 (KERN_WARNING) warning conditions
1372 5 (KERN_NOTICE) normal but significant condition
1373 6 (KERN_INFO) informational
1374 7 (KERN_DEBUG) debug-level messages
1376 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1377 in bytes. n must be a power of two. The default
1378 size is set in the kernel config file.
1380 logo.nologo [FB] Disables display of the built-in Linux logo.
1381 This may be used to provide more screen space for
1382 kernel log messages and is useful when debugging
1383 kernel boot problems.
1385 lp=0 [LP] Specify parallel ports to use, e.g,
1386 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1387 lp=reset first parallel port). 'lp=0' disables the
1388 lp=auto printer driver. 'lp=reset' (which can be
1389 specified in addition to the ports) causes
1390 attached printers to be reset. Using
1391 lp=port1,port2,... specifies the parallel ports
1392 to associate lp devices with, starting with
1393 lp0. A port specification may be 'none' to skip
1394 that lp device, or a parport name such as
1395 'parport0'. Specifying 'lp=auto' instead of a
1396 port specification list means that device IDs
1397 from each port should be examined, to see if
1398 an IEEE 1284-compliant printer is attached; if
1399 so, the driver will manage that printer.
1400 See also header of drivers/char/lp.c.
1403 Sets loops_per_jiffy to given constant, thus avoiding
1404 time-consuming boot-time autodetection (up to 250 ms per
1405 CPU). 0 enables autodetection (default). To determine
1406 the correct value for your kernel, boot with normal
1407 autodetection and see what value is printed. Note that
1408 on SMP systems the preset will be applied to all CPUs,
1409 which is likely to cause problems if your CPUs need
1410 significantly divergent settings. An incorrect value
1411 will cause delays in the kernel to be wrong, leading to
1412 unpredictable I/O errors and other breakage. Although
1413 unlikely, in the extreme case this might damage your
1417 Format: <io>,<irq>,<dma>
1419 machvec= [IA-64] Force the use of a particular machine-vector
1420 (machvec) in a generic kernel.
1421 Example: machvec=hpzx1_swiotlb
1423 machtype= [Loongson] Share the same kernel image file between different
1425 Example: machtype=lemote-yeeloong-2f-7inch
1427 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1428 than or equal to this physical address is ignored.
1430 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1431 should make use of. maxcpus=n : n >= 0 limits the
1432 kernel to using 'n' processors. n=0 is a special case,
1433 it is equivalent to "nosmp", which also disables
1436 max_loop= [LOOP] The number of loop block devices that get
1437 (loop.max_loop) unconditionally pre-created at init time. The default
1438 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1439 of statically allocating a predefined number, loop
1440 devices can be requested on-demand with the
1441 /dev/loop-control interface.
1445 mce [X86-32] Machine Check Exception
1447 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1449 md= [HW] RAID subsystems devices and level
1450 See Documentation/md.txt.
1453 Format: <first>,<last>
1454 Specifies range of consoles to be captured by the MDA.
1456 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1457 Amount of memory to be used when the kernel is not able
1458 to see the whole system memory or for test.
1459 [X86-32] Use together with memmap= to avoid physical
1460 address space collisions. Without memmap= PCI devices
1461 could be placed at addresses belonging to unused RAM.
1463 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1467 [KNL,SH] Allow user to override the default size for
1468 per-device physically contiguous DMA buffers.
1470 memmap=exactmap [KNL,X86] Enable setting of an exact
1471 E820 memory map, as specified by the user.
1472 Such memmap=exactmap lines can be constructed based on
1473 BIOS output or other requirements. See the memmap=nn@ss
1476 memmap=nn[KMG]@ss[KMG]
1477 [KNL] Force usage of a specific region of memory
1478 Region of memory to be used, from ss to ss+nn.
1480 memmap=nn[KMG]#ss[KMG]
1481 [KNL,ACPI] Mark specific memory as ACPI data.
1482 Region of memory to be used, from ss to ss+nn.
1484 memmap=nn[KMG]$ss[KMG]
1485 [KNL,ACPI] Mark specific memory as reserved.
1486 Region of memory to be used, from ss to ss+nn.
1487 Example: Exclude memory from 0x18690000-0x1869ffff
1488 memmap=64K$0x18690000
1490 memmap=0x10000$0x18690000
1492 memory_corruption_check=0/1 [X86]
1493 Some BIOSes seem to corrupt the first 64k of
1494 memory when doing things like suspend/resume.
1495 Setting this option will scan the memory
1496 looking for corruption. Enabling this will
1497 both detect corruption and prevent the kernel
1498 from using the memory being corrupted.
1499 However, its intended as a diagnostic tool; if
1500 repeatable BIOS-originated corruption always
1501 affects the same memory, you can use memmap=
1502 to prevent the kernel from using that memory.
1504 memory_corruption_check_size=size [X86]
1505 By default it checks for corruption in the low
1506 64k, making this memory unavailable for normal
1507 use. Use this parameter to scan for
1508 corruption in more or less memory.
1510 memory_corruption_check_period=seconds [X86]
1511 By default it checks for corruption every 60
1512 seconds. Use this parameter to check at some
1513 other rate. 0 disables periodic checking.
1515 memtest= [KNL,X86] Enable memtest
1517 default : 0 <disable>
1518 Specifies the number of memtest passes to be
1519 performed. Each pass selects another test
1520 pattern from a given set of patterns. Memtest
1521 fills the memory with this pattern, validates
1522 memory contents and reserves bad memory
1523 regions that are detected.
1525 meye.*= [HW] Set MotionEye Camera parameters
1526 See Documentation/video4linux/meye.txt.
1528 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1529 Multi-Function General Purpose Timers on AMD Geode
1532 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1533 the BIOS has incorrectly applied a workaround. TinyBIOS
1534 version 0.98 is known to be affected, 0.99 fixes the
1535 problem by letting the user disable the workaround.
1539 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1540 physical address is ignored.
1542 mini2440= [ARM,HW,KNL]
1543 Format:[0..2][b][c][t]
1545 MINI2440 configuration specification:
1546 0 - The attached screen is the 3.5" TFT
1547 1 - The attached screen is the 7" TFT
1548 2 - The VGA Shield is attached (1024x768)
1549 Leaving out the screen size parameter will not load
1550 the TFT driver, and the framebuffer will be left
1552 b - Enable backlight. The TFT backlight pin will be
1553 linked to the kernel VESA blanking code and a GPIO
1554 LED. This parameter is not necessary when using the
1556 c - Enable the s3c camera interface.
1557 t - Reserved for enabling touchscreen support. The
1558 touchscreen support is not enabled in the mainstream
1559 kernel as of 2.6.30, a preliminary port can be found
1560 in the "bleeding edge" mini2440 support kernel at
1561 http://repo.or.cz/w/linux-2.6/mini2440.git
1564 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1565 parameter allows control of the logging verbosity for
1566 the additional memory initialisation checks. A value
1567 of 0 disables mminit logging and a level of 4 will
1568 log everything. Information is printed at KERN_DEBUG
1569 so loglevel=8 may also need to be specified.
1572 [MOUSE] Maximum time between finger touching and
1573 leaving touchpad surface for touch to be considered
1574 a tap and be reported as a left button click (for
1575 touchpads working in absolute mode only).
1577 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1578 reporting absolute coordinates, such as tablets
1579 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1580 reporting absolute coordinates, such as tablets
1582 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1583 is similar to kernelcore except it specifies the
1584 amount of memory used for migratable allocations.
1585 If both kernelcore and movablecore is specified,
1586 then kernelcore will be at *least* the specified
1587 value but may be more. If movablecore on its own
1588 is specified, the administrator must be careful
1589 that the amount of memory usable for all allocations
1592 MTD_Partition= [MTD]
1593 Format: <name>,<region-number>,<size>,<offset>
1595 MTD_Region= [MTD] Format:
1596 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1599 See drivers/mtd/cmdlinepart.c.
1601 multitce=off [PPC] This parameter disables the use of the pSeries
1602 firmware feature for updating multiple TCE entries
1605 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1607 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1609 boundary - index of last SLC block on Flex-OneNAND.
1610 The remaining blocks are configured as MLC blocks.
1611 lock - Configure if Flex-OneNAND boundary should be locked.
1612 Once locked, the boundary cannot be changed.
1613 1 indicates lock status, 0 indicates unlock status.
1616 ARM/S3C2412 JIVE boot control
1618 See arch/arm/mach-s3c2412/mach-jive.c
1620 mtouchusb.raw_coordinates=
1621 [HW] Make the MicroTouch USB driver use raw coordinates
1622 ('y', default) or cooked coordinates ('n')
1624 mtrr_chunk_size=nn[KMG] [X86]
1625 used for mtrr cleanup. It is largest continuous chunk
1626 that could hold holes aka. UC entries.
1628 mtrr_gran_size=nn[KMG] [X86]
1629 Used for mtrr cleanup. It is granularity of mtrr block.
1631 Large value could prevent small alignment from
1634 mtrr_spare_reg_nr=n [X86]
1636 Range: 0,7 : spare reg number
1638 Used for mtrr cleanup. It is spare mtrr entries number.
1639 Set to 2 or more if your graphical card needs more.
1641 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1643 netdev= [NET] Network devices parameters
1644 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1645 Note that mem_start is often overloaded to mean
1646 something different and driver-specific.
1647 This usage is only documented in each driver source
1651 [NETFILTER] Enable connection tracking flow accounting
1652 0 to disable accounting
1653 1 to enable accounting
1656 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1657 See Documentation/filesystems/nfs/nfsroot.txt.
1659 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1660 See Documentation/filesystems/nfs/nfsroot.txt.
1662 nfsrootdebug [NFS] enable nfsroot debugging messages.
1663 See Documentation/filesystems/nfs/nfsroot.txt.
1665 nfs.callback_tcpport=
1666 [NFS] set the TCP port on which the NFSv4 callback
1667 channel should listen.
1670 [NFS] sets the pathname to the program which is used
1671 to update the NFS client cache entries.
1673 nfs.cache_getent_timeout=
1674 [NFS] sets the timeout after which an attempt to
1675 update a cache entry is deemed to have failed.
1677 nfs.idmap_cache_timeout=
1678 [NFS] set the maximum lifetime for idmapper cache
1682 [NFS] enable 64-bit inode numbers.
1683 If zero, the NFS client will fake up a 32-bit inode
1684 number for the readdir() and stat() syscalls instead
1685 of returning the full 64-bit number.
1686 The default is to return 64-bit inode numbers.
1688 nfs.nfs4_disable_idmapping=
1689 [NFSv4] When set, this option disables the NFSv4
1690 idmapper on the client, but only if the mount
1691 is using the 'sec=sys' security flavour. This may
1692 make migration from legacy NFSv2/v3 systems easier
1693 provided that the server has the appropriate support.
1694 The default is to always enable NFSv4 idmapping.
1696 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1697 when a NMI is triggered.
1698 Format: [state][,regs][,debounce][,die]
1700 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1701 Format: [panic,][nopanic,][num]
1703 0 - turn nmi_watchdog off
1704 When panic is specified, panic when an NMI watchdog
1705 timeout occurs (or 'nopanic' to override the opposite
1707 This is useful when you use a panic=... timeout and
1708 need the box quickly up again.
1710 netpoll.carrier_timeout=
1711 [NET] Specifies amount of time (in seconds) that
1712 netpoll should wait for a carrier. By default netpoll
1715 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1716 emulation library even if a 387 maths coprocessor
1720 [HW] Never suspend the console
1721 Disable suspending of consoles during suspend and
1722 hibernate operations. Once disabled, debugging
1723 messages can reach various consoles while the rest
1724 of the system is being put to sleep (ie, while
1725 debugging driver suspend/resume hooks). This may
1726 not work reliably with all consoles, but is known
1727 to work with serial and VGA consoles.
1728 To facilitate more flexible debugging, we also add
1729 console_suspend, a printk module parameter to control
1730 it. Users could use console_suspend (usually
1731 /sys/module/printk/parameters/console_suspend) to
1732 turn on/off it dynamically.
1734 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1735 caches in the slab allocator. Saves per-node memory,
1736 but will impact performance.
1740 noapic [SMP,APIC] Tells the kernel to not make use of any
1741 IOAPICs that may be present in the system.
1743 noautogroup Disable scheduler automatic task group creation.
1745 nobats [PPC] Do not use BATs for mapping kernel lowmem
1746 on "Classic" PPC cores.
1750 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1752 nodelayacct [KNL] Disable per-task delay accounting
1754 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1756 nodsp [SH] Disable hardware DSP at boot time.
1758 noefi [X86] Disable EFI runtime services support.
1763 On X86-32 available only on PAE configured kernels.
1764 noexec=on: enable non-executable mappings (default)
1765 noexec=off: disable non-executable mappings
1768 Disable SMEP (Supervisor Mode Execution Protection)
1769 even if it is supported by processor.
1772 This affects only 32-bit executables.
1773 noexec32=on: enable non-executable mappings (default)
1774 read doesn't imply executable mappings
1775 noexec32=off: disable non-executable mappings
1776 read implies executable mappings
1778 nofpu [SH] Disable hardware FPU at boot time.
1780 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1781 register save and restore. The kernel will only save
1782 legacy floating-point registers on task switch.
1784 nospectre_v2 [X86] Disable all mitigations for the Spectre variant 2
1785 (indirect branch prediction) vulnerability. System may
1786 allow data leaks with this option, which is equivalent
1789 noxsave [BUGS=X86] Disables x86 extended register state save
1790 and restore using xsave. The kernel will fallback to
1791 enabling legacy floating-point and sse state.
1793 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1794 wfi(ARM) instruction doesn't work correctly and not to
1795 use it. This is also useful when using JTAG debugger.
1797 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1798 instruction doesn't work correctly and not to
1801 no_file_caps Tells the kernel not to honor file capabilities. The
1802 only way then for a file to be executed with privilege
1803 is to be setuid root or executed by root.
1805 nohalt [IA-64] Tells the kernel not to use the power saving
1806 function PAL_HALT_LIGHT when idle. This increases
1807 power-consumption. On the positive side, it reduces
1808 interrupt wake-up latency, which may improve performance
1809 in certain environments such as networked servers or
1812 nohz= [KNL] Boottime enable/disable dynamic ticks
1813 Valid arguments: on, off
1816 noiotrap [SH] Disables trapped I/O port accesses.
1818 noirqdebug [X86-32] Disables the code which attempts to detect and
1819 disable unhandled interrupt sources.
1821 no_timer_check [X86,APIC] Disables the code which tests for
1822 broken timer IRQ sources.
1824 noisapnp [ISAPNP] Disables ISA PnP code.
1826 noinitrd [RAM] Tells the kernel not to load any configured
1829 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1831 [Deprecated - use intremap=off]
1835 noinvpcid [X86] Disable the INVPCID cpu feature.
1837 nojitter [IA-64] Disables jitter checking for ITC timers.
1839 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1841 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1844 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1845 steal time is computed, but won't influence scheduler
1848 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1850 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1852 noltlbs [PPC] Do not use large page/tlb entries for kernel
1853 lowmem mapping on PPC40x.
1855 nomca [IA-64] Disable machine check abort handling
1857 nomce [X86-32] Machine Check Exception
1859 nomfgpt [X86-32] Disable Multi-Function General Purpose
1860 Timer usage (for AMD Geode machines).
1862 nopat [X86] Disable PAT (page attribute table extension of
1863 pagetables) support.
1865 nopcid [X86-64] Disable the PCID cpu feature.
1867 norandmaps Don't use address space randomization. Equivalent to
1868 echo 0 > /proc/sys/kernel/randomize_va_space
1870 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1871 with UP alternatives
1873 noresidual [PPC] Don't use residual data on PReP machines.
1875 nordrand [X86] Disable the direct use of the RDRAND
1876 instruction even if it is supported by the
1877 processor. RDRAND is still available to user
1880 noresume [SWSUSP] Disables resume and restores original swap
1883 no-scroll [VGA] Disables scrollback.
1884 This is required for the Braillex ib80-piezo Braille
1885 reader made by F.H. Papenmeier (Germany).
1889 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1891 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1892 and disable the IO APIC. legacy for "maxcpus=0".
1894 nosoftlockup [KNL] Disable the soft-lockup detector.
1896 nosync [HW,M68K] Disables sync negotiation for all devices.
1898 notsc [BUGS=X86-32] Disable Time Stamp Counter
1900 nousb [USB] Disable the USB subsystem
1902 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1906 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1908 nptcg= [IA-64] Override max number of concurrent global TLB
1909 purges which is reported from either PAL_VM_SUMMARY or
1912 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1913 could support. nr_cpus=n : n >= 1 limits the kernel to
1914 supporting 'n' processors. Later in runtime you can not
1915 use hotplug cpu feature to put more cpu back to online.
1916 just like you compile the kernel NR_CPUS=n
1918 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1920 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1921 one of ['zone', 'node', 'default'] can be specified
1922 This can be set from sysctl after boot.
1923 See Documentation/sysctl/vm.txt for details.
1925 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1926 See Documentation/debugging-via-ohci1394.txt for more
1929 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1930 Rather than timing out after 20 ms if an EC
1931 command is not properly ACKed, override the length
1932 of the timeout. We have interrupts disabled while
1933 waiting for the ACK, so if this is set too high
1934 interrupts *may* be lost!
1936 omap_mux= [OMAP] Override bootloader pin multiplexing.
1937 Format: <mux_mode0.mode_name=value>...
1938 For example, to override I2C bus2:
1939 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1941 oprofile.timer= [HW]
1942 Use timer interrupt instead of performance counters
1944 oprofile.cpu_type= Force an oprofile cpu type
1945 This might be useful if you have an older oprofile
1946 userland or if you want common events.
1947 Format: { arch_perfmon }
1948 arch_perfmon: [X86] Force use of architectural
1949 perfmon on Intel CPUs instead of the
1950 CPU specific event set.
1952 oops=panic Always panic on oopses. Default is to just kill the
1953 process, but there is a small probability of
1954 deadlocking the machine.
1955 This will also cause panics on machine check exceptions.
1956 Useful together with panic=30 to trigger a reboot.
1959 See Documentation/sound/oss/oss-parameters.txt
1961 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1962 timeout > 0: seconds before rebooting
1963 timeout = 0: wait forever
1964 timeout < 0: reboot immediately
1967 parkbd.port= [HW] Parallel port number the keyboard adapter is
1968 connected to, default is 0.
1970 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1971 0 for XT, 1 for AT (default is AT).
1974 parport= [HW,PPT] Specify parallel ports. 0 disables.
1975 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1976 Use 'auto' to force the driver to use any
1977 IRQ/DMA settings detected (the default is to
1978 ignore detected IRQ/DMA settings because of
1979 possible conflicts). You can specify the base
1980 address, IRQ, and DMA settings; IRQ and DMA
1981 should be numbers, or 'auto' (for using detected
1982 settings on that particular port), or 'nofifo'
1983 (to avoid using a FIFO even if it is detected).
1984 Parallel ports are assigned in the order they
1985 are specified on the command line, starting
1988 parport_init_mode= [HW,PPT]
1989 Configure VIA parallel port to operate in
1990 a specific mode. This is necessary on Pegasos
1991 computer where firmware has no options for setting
1992 up parallel port mode and sets it to spp.
1993 Currently this function knows 686a and 8231 chips.
1994 Format: [spp|ps2|epp|ecp|ecpepp]
1997 Halt all CPUs after the first oops has been printed for
1998 the specified number of seconds. This is to be used if
1999 your oopses keep scrolling off the screen.
2004 See header of drivers/block/paride/pcd.c.
2005 See also Documentation/blockdev/paride.txt.
2007 pci=option[,option...] [PCI] various PCI subsystem options:
2008 earlydump [X86] dump PCI config space before the kernel
2010 off [X86] don't probe for the PCI bus
2011 bios [X86-32] force use of PCI BIOS, don't access
2012 the hardware directly. Use this if your machine
2013 has a non-standard PCI host bridge.
2014 nobios [X86-32] disallow use of PCI BIOS, only direct
2015 hardware access methods are allowed. Use this
2016 if you experience crashes upon bootup and you
2017 suspect they are caused by the BIOS.
2018 conf1 [X86] Force use of PCI Configuration
2020 conf2 [X86] Force use of PCI Configuration
2022 noaer [PCIE] If the PCIEAER kernel config parameter is
2023 enabled, this kernel boot option can be used to
2024 disable the use of PCIE advanced error reporting.
2025 nodomains [PCI] Disable support for multiple PCI
2026 root domains (aka PCI segments, in ACPI-speak).
2027 nommconf [X86] Disable use of MMCONFIG for PCI
2029 check_enable_amd_mmconf [X86] check for and enable
2030 properly configured MMIO access to PCI
2031 config space on AMD family 10h CPU
2032 nomsi [MSI] If the PCI_MSI kernel config parameter is
2033 enabled, this kernel boot option can be used to
2034 disable the use of MSI interrupts system-wide.
2035 noioapicquirk [APIC] Disable all boot interrupt quirks.
2036 Safety option to keep boot IRQs enabled. This
2037 should never be necessary.
2038 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2039 primary IO-APIC for bridges that cannot disable
2040 boot IRQs. This fixes a source of spurious IRQs
2041 when the system masks IRQs.
2042 noioapicreroute [APIC] Disable workaround that uses the
2043 boot IRQ equivalent of an IRQ that connects to
2044 a chipset where boot IRQs cannot be disabled.
2045 The opposite of ioapicreroute.
2046 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2047 routing table. These calls are known to be buggy
2048 on several machines and they hang the machine
2049 when used, but on other computers it's the only
2050 way to get the interrupt routing table. Try
2051 this option if the kernel is unable to allocate
2052 IRQs or discover secondary PCI buses on your
2054 rom [X86] Assign address space to expansion ROMs.
2055 Use with caution as certain devices share
2056 address decoders between ROMs and other
2058 norom [X86] Do not assign address space to
2059 expansion ROMs that do not already have
2060 BIOS assigned address ranges.
2061 nobar [X86] Do not assign address space to the
2062 BARs that weren't assigned by the BIOS.
2063 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2064 assigned automatically to PCI devices. You can
2065 make the kernel exclude IRQs of your ISA cards
2067 pirqaddr=0xAAAAA [X86] Specify the physical address
2068 of the PIRQ table (normally generated
2069 by the BIOS) if it is outside the
2070 F0000h-100000h range.
2071 lastbus=N [X86] Scan all buses thru bus #N. Can be
2072 useful if the kernel is unable to find your
2073 secondary buses and you want to tell it
2074 explicitly which ones they are.
2075 assign-busses [X86] Always assign all PCI bus
2076 numbers ourselves, overriding
2077 whatever the firmware may have done.
2078 usepirqmask [X86] Honor the possible IRQ mask stored
2079 in the BIOS $PIR table. This is needed on
2080 some systems with broken BIOSes, notably
2081 some HP Pavilion N5400 and Omnibook XE3
2082 notebooks. This will have no effect if ACPI
2083 IRQ routing is enabled.
2084 noacpi [X86] Do not use ACPI for IRQ routing
2085 or for PCI scanning.
2086 use_crs [X86] Use PCI host bridge window information
2087 from ACPI. On BIOSes from 2008 or later, this
2088 is enabled by default. If you need to use this,
2089 please report a bug.
2090 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2091 If you need to use this, please report a bug.
2092 routeirq Do IRQ routing for all PCI devices.
2093 This is normally done in pci_enable_device(),
2094 so this option is a temporary workaround
2095 for broken drivers that don't call it.
2096 skip_isa_align [X86] do not align io start addr, so can
2097 handle more pci cards
2098 firmware [ARM] Do not re-enumerate the bus but instead
2099 just use the configuration from the
2100 bootloader. This is currently used on
2101 IXP2000 systems where the bus has to be
2102 configured a certain way for adjunct CPUs.
2103 noearly [X86] Don't do any early type 1 scanning.
2104 This might help on some broken boards which
2105 machine check when some devices' config space
2106 is read. But various workarounds are disabled
2107 and some IOMMU drivers will not work.
2108 bfsort Sort PCI devices into breadth-first order.
2109 This sorting is done to get a device
2110 order compatible with older (<= 2.4) kernels.
2111 nobfsort Don't sort PCI devices into breadth-first order.
2112 cbiosize=nn[KMG] The fixed amount of bus space which is
2113 reserved for the CardBus bridge's IO window.
2114 The default value is 256 bytes.
2115 cbmemsize=nn[KMG] The fixed amount of bus space which is
2116 reserved for the CardBus bridge's memory
2117 window. The default value is 64 megabytes.
2120 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2121 Specifies alignment and device to reassign
2122 aligned memory resources.
2123 If <order of align> is not specified,
2124 PAGE_SIZE is used as alignment.
2125 PCI-PCI bridge can be specified, if resource
2126 windows need to be expanded.
2127 ecrc= Enable/disable PCIe ECRC (transaction layer
2128 end-to-end CRC checking).
2129 bios: Use BIOS/firmware settings. This is the
2133 realloc reallocate PCI resources if allocations done by BIOS
2136 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2139 force Enable ASPM even on devices that claim not to support it.
2140 WARNING: Forcing ASPM on may cause system lockups.
2142 pcie_ports= [PCIE] PCIe ports handling:
2143 auto Ask the BIOS whether or not to use native PCIe services
2144 associated with PCIe ports (PME, hot-plug, AER). Use
2145 them only if that is allowed by the BIOS.
2146 native Use native PCIe services associated with PCIe ports
2148 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2151 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2152 nomsi Do not use MSI for native PCIe PME signaling (this makes
2153 all PCIe root ports use INTx for all services).
2155 pcmv= [HW,PCMCIA] BadgePAD 4
2158 See Documentation/blockdev/paride.txt.
2160 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2163 See arch/parisc/kernel/pdc_chassis.c
2165 percpu_alloc= Select which percpu first chunk allocator to use.
2166 Currently supported values are "embed" and "page".
2167 Archs may support subset or none of the selections.
2168 See comments in mm/percpu.c for details on each
2169 allocator. This parameter is primarily for debugging
2170 and performance comparison.
2173 See Documentation/blockdev/paride.txt.
2176 See Documentation/blockdev/paride.txt.
2178 pirq= [SMP,APIC] Manual mp-table setup
2179 See Documentation/x86/i386/IO-APIC.txt.
2181 plip= [PPT,NET] Parallel port network link
2182 Format: { parport<nr> | timid | 0 }
2183 See also Documentation/parport.txt.
2185 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2186 Override pmtimer IOPort with a hex value.
2190 Enable PNP debug messages (depends on the
2191 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2192 via /sys/module/pnp/parameters/debug. We always show
2193 current resource usage; turning this on also shows
2194 possible settings and some assignment information.
2200 { on | off | curr | res | no-curr | no-res }
2203 [ISAPNP] Exclude IRQs for the autoconfiguration
2206 [ISAPNP] Exclude DMAs for the autoconfiguration
2208 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2209 Ranges are in pairs (I/O port base and size).
2212 [ISAPNP] Exclude memory regions for the
2214 Ranges are in pairs (memory base and size).
2216 ports= [IP_VS_FTP] IPVS ftp helper module
2218 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2220 Format: <port>,<port>....
2222 print-fatal-signals=
2223 [KNL] debug: print fatal signals
2225 If enabled, warn about various signal handling
2226 related application anomalies: too many signals,
2227 too many POSIX.1 timers, fatal signals causing a
2230 If you hit the warning due to signal overflow,
2231 you might want to try "ulimit -i unlimited".
2235 printk.time= Show timing data prefixed to each printk message line
2236 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2238 processor.max_cstate= [HW,ACPI]
2239 Limit processor to maximum C-state
2240 max_cstate=9 overrides any DMI blacklist limit.
2242 processor.nocst [HW,ACPI]
2243 Ignore the _CST method to determine C-states,
2244 instead using the legacy FADT method
2246 profile= [KNL] Enable kernel profiling via /proc/profile
2247 Format: [schedule,]<number>
2248 Param: "schedule" - profile schedule points.
2249 Param: <number> - step/bucket size as a power of 2 for
2250 statistical time based profiling.
2251 Param: "sleep" - profile D-state sleeping (millisecs).
2252 Requires CONFIG_SCHEDSTATS
2253 Param: "kvm" - profile VM exits.
2255 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2257 See Documentation/blockdev/ramdisk.txt.
2259 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2260 probe for; one of (bare|imps|exps|lifebook|any).
2261 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2263 psmouse.resetafter= [HW,MOUSE]
2264 Try to reset the device after so many bad packets
2267 [HW,MOUSE] Set desired mouse resolution, in dpi.
2268 psmouse.smartscroll=
2269 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2270 0 = disabled, 1 = enabled (default).
2272 pstore.backend= Specify the name of the pstore backend to use
2275 See Documentation/blockdev/paride.txt.
2277 pti= [X86_64] Control Page Table Isolation of user and
2278 kernel address spaces. Disabling this feature
2279 removes hardening, but improves performance of
2280 system calls and interrupts.
2282 on - unconditionally enable
2283 off - unconditionally disable
2284 auto - kernel detects whether your CPU model is
2285 vulnerable to issues that PTI mitigates
2287 Not specifying this option is equivalent to pti=auto.
2290 Equivalent to pti=off
2293 [KNL] Number of legacy pty's. Overwrites compiled-in
2296 quiet [KNL] Disable most log messages
2301 See Documentation/md.txt.
2303 ramdisk_blocksize= [RAM]
2304 See Documentation/blockdev/ramdisk.txt.
2306 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2307 See Documentation/blockdev/ramdisk.txt.
2309 rcupdate.blimit= [KNL,BOOT]
2310 Set maximum number of finished RCU callbacks to process
2313 rcupdate.qhimark= [KNL,BOOT]
2314 Set threshold of queued
2315 RCU callbacks over which batch limiting is disabled.
2317 rcupdate.qlowmark= [KNL,BOOT]
2318 Set threshold of queued RCU callbacks below which
2319 batch limiting is re-enabled.
2323 Run specified binary instead of /init from the ramdisk,
2324 used for early userspace startup. See initrd.
2326 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2327 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2328 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2331 [KNL, SMP] Set scheduler's default relax_domain_level.
2332 See Documentation/cgroups/cpusets.txt.
2334 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2336 reservetop= [X86-32]
2338 Reserves a hole at the top of the kernel virtual
2343 Set the amount of memory to reserve for BIOS at
2344 the bottom of the address space.
2346 reset_devices [KNL] Force drivers to reset the underlying device
2347 during initialization.
2350 Specify the partition device for software suspend
2352 resume_offset= [SWSUSP]
2353 Specify the offset from the beginning of the partition
2354 given by "resume=" at which the swap header is located,
2355 in <PAGE_SIZE> units (needed only for swap files).
2356 See Documentation/power/swsusp-and-swap-files.txt
2358 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2359 read the resume files
2361 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2362 Useful for devices that are detected asynchronously
2363 (e.g. USB and MMC devices).
2365 hibernate= [HIBERNATION]
2366 noresume Don't check if there's a hibernation image
2367 present during boot.
2368 nocompress Don't compress/decompress hibernation images.
2370 retain_initrd [RAM] Keep initrd memory after extraction
2372 rhash_entries= [KNL,NET]
2373 Set number of hash buckets for route cache
2375 riscom8= [HW,SERIAL]
2376 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2378 ro [KNL] Mount root device read-only on boot
2380 root= [KNL] Root filesystem
2381 See name_to_dev_t comment in init/do_mounts.c.
2383 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2384 mount the root filesystem
2386 rootflags= [KNL] Set root filesystem mount option string
2388 rootfstype= [KNL] Set root filesystem type
2390 rootwait [KNL] Wait (indefinitely) for root device to show up.
2391 Useful for devices that are detected asynchronously
2392 (e.g. USB and MMC devices).
2394 rw [KNL] Mount root device read-write on boot
2396 S [KNL] Run init in single mode
2399 See drivers/net/irda/sa1100_ir.c.
2401 sbni= [NET] Granch SBNI12 leased line adapter
2403 sched_debug [KNL] Enables verbose scheduler debug messages.
2405 security= [SECURITY] Choose a security module to enable at boot.
2406 If this boot parameter is not specified, only the first
2407 security module asking for security registration will be
2408 loaded. An invalid security module name will be treated
2409 as if no module has been chosen.
2411 selinux= [SELINUX] Disable or enable SELinux at boot time.
2412 Format: { "0" | "1" }
2413 See security/selinux/Kconfig help text.
2416 Default value is set via kernel config option.
2417 If enabled at boot time, /selinux/disable can be used
2418 later to disable prior to initial policy load.
2420 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2421 Format: { "0" | "1" }
2422 See security/apparmor/Kconfig help text
2425 Default value is set via kernel config option.
2427 serialnumber [BUGS=X86-32]
2430 Maximal number of shapers.
2432 show_msr= [x86] show boot-time MSR settings
2433 Format: { <integer> }
2434 Show boot-time (BIOS-initialized) MSR settings.
2435 The parameter means the number of CPUs to show,
2436 for example 1 means boot CPU only.
2443 slub_debug[=options[,slabs]] [MM, SLUB]
2444 Enabling slub_debug allows one to determine the
2445 culprit if slab objects become corrupted. Enabling
2446 slub_debug can create guard zones around objects and
2447 may poison objects when not in use. Also tracks the
2448 last alloc / free. For more information see
2449 Documentation/vm/slub.txt.
2451 slub_max_order= [MM, SLUB]
2452 Determines the maximum allowed order for slabs.
2453 A high setting may cause OOMs due to memory
2454 fragmentation. For more information see
2455 Documentation/vm/slub.txt.
2457 slub_min_objects= [MM, SLUB]
2458 The minimum number of objects per slab. SLUB will
2459 increase the slab order up to slub_max_order to
2460 generate a sufficiently large slab able to contain
2461 the number of objects indicated. The higher the number
2462 of objects the smaller the overhead of tracking slabs
2463 and the less frequently locks need to be acquired.
2464 For more information see Documentation/vm/slub.txt.
2466 slub_min_order= [MM, SLUB]
2467 Determines the mininum page order for slabs. Must be
2468 lower than slub_max_order.
2469 For more information see Documentation/vm/slub.txt.
2471 slub_nomerge [MM, SLUB]
2472 Disable merging of slabs with similar size. May be
2473 necessary if there is some reason to distinguish
2474 allocs to different slabs. Debug options disable
2475 merging on their own.
2476 For more information see Documentation/vm/slub.txt.
2479 Format: <io1>[,<io2>[,...,<io8>]]
2481 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2482 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2483 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2484 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2485 smsc-ircc2.ircc_irq= [HW] IRQ line
2486 smsc-ircc2.ircc_dma= [HW] DMA channel
2487 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2488 0: Toshiba Satellite 1800 (GP data pin select)
2489 1: Fast pin select (default)
2493 [KNL] Should the soft-lockup detector generate panics.
2496 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2497 See Documentation/laptops/sonypi.txt
2499 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2500 See Documentation/serial/specialix.txt.
2502 spectre_v2= [X86] Control mitigation of Spectre variant 2
2503 (indirect branch speculation) vulnerability.
2505 on - unconditionally enable
2506 off - unconditionally disable
2507 auto - kernel detects whether your CPU model is
2510 Selecting 'on' will, and 'auto' may, choose a
2511 mitigation method at run time according to the
2512 CPU, the available microcode, the setting of the
2513 CONFIG_RETPOLINE configuration option, and the
2514 compiler with which the kernel was built.
2516 Specific mitigations can also be selected manually:
2518 retpoline - replace indirect branches
2519 retpoline,generic - google's original retpoline
2520 retpoline,amd - AMD-specific minimal thunk
2522 Not specifying this option is equivalent to
2525 spia_io_base= [HW,MTD]
2530 stack_guard_gap= [MM]
2531 override the default stack gap protection. The value
2532 is in page units and it defines how many pages prior
2533 to (for stacks growing down) resp. after (for stacks
2534 growing up) the main stack are reserved for no other
2535 mapping. Default value is 256 pages.
2538 Enabled the stack tracer on boot up.
2542 Set the STI (builtin display/keyboard on the HP-PARISC
2543 machines) console (graphic card) which should be used
2544 as the initial boot-console.
2545 See also comment in drivers/video/console/sticore.c.
2548 See comment in drivers/video/console/sticore.c.
2551 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2553 sunrpc.min_resvport=
2554 sunrpc.max_resvport=
2556 SunRPC servers often require that client requests
2557 originate from a privileged port (i.e. a port in the
2558 range 0 < portnr < 1024).
2559 An administrator who wishes to reserve some of these
2560 ports for other uses may adjust the range that the
2561 kernel's sunrpc client considers to be privileged
2562 using these two parameters to set the minimum and
2563 maximum port values.
2567 Control how the NFS server code allocates CPUs to
2568 service thread pools. Depending on how many NICs
2569 you have and where their interrupts are bound, this
2570 option will affect which CPUs will do NFS serving.
2571 Note: this parameter cannot be changed while the
2572 NFS server is running.
2574 auto the server chooses an appropriate mode
2575 automatically using heuristics
2576 global a single global pool contains all CPUs
2577 percpu one pool for each CPU
2578 pernode one pool for each NUMA node (equivalent
2579 to global on non-NUMA machines)
2581 sunrpc.tcp_slot_table_entries=
2582 sunrpc.udp_slot_table_entries=
2584 Sets the upper limit on the number of simultaneous
2585 RPC calls that can be sent from the client to a
2586 server. Increasing these values may allow you to
2587 improve throughput, but will also increase the
2588 amount of memory reserved for use by the client.
2591 [KNL] Enable accounting of swap in memory resource
2592 controller if no parameter or 1 is given or disable
2593 it if 0 is given (See Documentation/cgroups/memory.txt)
2595 swiotlb= [IA-64] Number of I/O TLB slabs
2599 sysfs.deprecated=0|1 [KNL]
2600 Enable/disable old style sysfs layout for old udev
2601 on older distributions. When this option is enabled
2602 very new udev will not work anymore. When this option
2603 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2604 in older udev will not work anymore.
2605 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2606 the kernel configuration.
2608 sysrq_always_enabled
2610 Ignore sysrq setting - this boot parameter will
2611 neutralize any effect of /proc/sys/kernel/sysrq.
2612 Useful for debugging.
2616 test_suspend= [SUSPEND]
2617 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2618 standby suspend) as the system sleep state to briefly
2619 enter during system startup. The system is woken from
2620 this state using a wakeup-capable RTC alarm.
2622 thash_entries= [KNL,NET]
2623 Set number of hash buckets for TCP connection
2625 thermal.act= [HW,ACPI]
2626 -1: disable all active trip points in all thermal zones
2627 <degrees C>: override all lowest active trip points
2629 thermal.crt= [HW,ACPI]
2630 -1: disable all critical trip points in all thermal zones
2631 <degrees C>: override all critical trip points
2633 thermal.nocrt= [HW,ACPI]
2634 Set to disable actions on ACPI thermal zone
2635 critical and hot trip points.
2637 thermal.off= [HW,ACPI]
2638 1: disable ACPI thermal control
2640 thermal.psv= [HW,ACPI]
2641 -1: disable all passive trip points
2642 <degrees C>: override all passive trip points to this
2645 thermal.tzp= [HW,ACPI]
2646 Specify global default ACPI thermal zone polling rate
2647 <deci-seconds>: poll all this frequency
2648 0: no polling (default)
2651 Force threading of all interrupt handlers except those
2652 marked explicitely IRQF_NO_THREAD.
2656 Specify if the kernel should make use of the cpu
2657 topology information if the hardware supports this.
2658 The scheduler will make use of this information and
2659 e.g. base its process migration decisions on it.
2664 tpm_suspend_pcr=[HW,TPM]
2665 Format: integer pcr id
2666 Specify that at suspend time, the tpm driver
2667 should extend the specified pcr with zeros,
2668 as a workaround for some chips which fail to
2669 flush the last written pcr on TPM_SaveState.
2670 This will guarantee that all the other pcrs
2673 trace_buf_size=nn[KMG]
2674 [FTRACE] will set tracing buffer size.
2676 trace_event=[event-list]
2677 [FTRACE] Set and start specified trace events in order
2678 to facilitate early boot debugging.
2679 See also Documentation/trace/events.txt
2681 tsc= Disable clocksource stability checks for TSC.
2683 [x86] reliable: mark tsc clocksource as reliable, this
2684 disables clocksource verification at runtime, as well
2685 as the stability checks done at bootup. Used to enable
2686 high-resolution timer mode on older hardware, and in
2687 virtualized environment.
2688 [x86] noirqtime: Do not use TSC to do irq accounting.
2689 Used to run time disable IRQ_TIME_ACCOUNTING on any
2690 platforms where RDTSC is slow and this accounting
2693 turbografx.map[2|3]= [HW,JOY]
2694 TurboGraFX parallel port interface
2696 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2697 See also Documentation/input/joystick-parport.txt
2699 udbg-immortal [PPC] When debugging early kernel crashes that
2700 happen after console_init() and before a proper
2701 console driver takes over, this boot options might
2702 help "seeing" what's going on.
2704 uhash_entries= [KNL,NET]
2705 Set number of hash buckets for UDP/UDP-Lite connections
2708 [USB] Ignore overcurrent events (default N).
2709 Some badly-designed motherboards generate lots of
2710 bogus events, for ports that aren't wired to
2711 anything. Set this parameter to avoid log spamming.
2712 Note that genuine overcurrent events won't be
2716 [X86] Cause panic on unknown NMI.
2718 usbcore.authorized_default=
2719 [USB] Default USB device authorization:
2720 (default -1 = authorized except for wireless USB,
2721 0 = not authorized, 1 = authorized)
2723 usbcore.autosuspend=
2724 [USB] The autosuspend time delay (in seconds) used
2725 for newly-detected USB devices (default 2). This
2726 is the time required before an idle device will be
2727 autosuspended. Devices for which the delay is set
2728 to a negative value won't be autosuspended at all.
2730 usbcore.usbfs_snoop=
2731 [USB] Set to log all usbfs traffic (default 0 = off).
2733 usbcore.blinkenlights=
2734 [USB] Set to cycle leds on hubs (default 0 = off).
2736 usbcore.old_scheme_first=
2737 [USB] Start with the old device initialization
2738 scheme (default 0 = off).
2740 usbcore.use_both_schemes=
2741 [USB] Try the other device initialization scheme
2742 if the first one fails (default 1 = enabled).
2744 usbcore.initial_descriptor_timeout=
2745 [USB] Specifies timeout for the initial 64-byte
2746 USB_REQ_GET_DESCRIPTOR request in milliseconds
2747 (default 5000 = 5.0 seconds).
2750 [USBHID] The interval which mice are to be polled at.
2752 usb-storage.delay_use=
2753 [UMS] The delay in seconds before a new device is
2754 scanned for Logical Units (default 5).
2757 [UMS] A list of quirks entries to supplement or
2758 override the built-in unusual_devs list. List
2759 entries are separated by commas. Each entry has
2760 the form VID:PID:Flags where VID and PID are Vendor
2761 and Product ID values (4-digit hex numbers) and
2762 Flags is a set of characters, each corresponding
2763 to a common usb-storage quirk flag as follows:
2764 a = SANE_SENSE (collect more than 18 bytes
2766 b = BAD_SENSE (don't collect more than 18
2767 bytes of sense data);
2768 c = FIX_CAPACITY (decrease the reported
2769 device capacity by one sector);
2770 d = NO_READ_DISC_INFO (don't use
2771 READ_DISC_INFO command);
2772 e = NO_READ_CAPACITY_16 (don't use
2773 READ_CAPACITY_16 command);
2774 h = CAPACITY_HEURISTICS (decrease the
2775 reported device capacity by one
2776 sector if the number is odd);
2777 i = IGNORE_DEVICE (don't bind to this
2779 j = NO_REPORT_LUNS (don't use report luns
2781 l = NOT_LOCKABLE (don't try to lock and
2782 unlock ejectable media);
2783 m = MAX_SECTORS_64 (don't transfer more
2784 than 64 sectors = 32 KB at a time);
2785 n = INITIAL_READ10 (force a retry of the
2786 initial READ(10) command);
2787 o = CAPACITY_OK (accept the capacity
2788 reported by the device);
2789 r = IGNORE_RESIDUE (the device reports
2790 bogus residue values);
2791 s = SINGLE_LUN (the device has only one
2793 w = NO_WP_DETECT (don't test whether the
2794 medium is write-protected).
2795 Example: quirks=0419:aaf5:rl,0421:0433:rc
2797 user_debug= [KNL,ARM]
2799 See arch/arm/Kconfig.debug help text.
2800 1 - undefined instruction events
2802 4 - invalid data aborts
2805 Example: user_debug=31
2808 [X86] Flags controlling user PTE allocations.
2810 nohigh = do not allocate PTE pages in
2811 HIGHMEM regardless of setting
2815 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2816 vdso=1: enable VDSO (default)
2817 vdso=0: disable VDSO mapping
2820 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2821 vdso32=1: enable 32-bit VDSO (default)
2822 vdso32=0: disable 32-bit VDSO mapping
2825 vector=percpu: enable percpu vector domain
2827 video= [FB] Frame buffer configuration
2828 See Documentation/fb/modedb.txt.
2830 vga= [BOOT,X86-32] Select a particular video mode
2831 See Documentation/x86/boot.txt and
2832 Documentation/svga.txt.
2833 Use vga=ask for menu.
2834 This is actually a boot loader parameter; the value is
2835 passed to the kernel using a special protocol.
2837 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2838 size of <nn>. This can be used to increase the
2839 minimum size (128MB on x86). It can also be used to
2840 decrease the size and leave more room for directly
2843 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2846 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2849 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2853 Controls the behavior of vsyscalls (i.e. calls to
2854 fixed addresses of 0xffffffffff600x00 from legacy
2855 code). Most statically-linked binaries and older
2856 versions of glibc use these calls. Because these
2857 functions are at fixed addresses, they make nice
2858 targets for exploits that can control RIP.
2860 emulate Vsyscalls turn into traps and are emulated
2863 native [default] Vsyscalls are native syscall
2865 This is a little bit faster than trapping
2866 and makes a few dynamic recompilers work
2867 better than they would in emulation mode.
2868 It also makes exploits much easier to write.
2870 none Vsyscalls don't work at all. This makes
2871 them quite hard to use for exploits but
2872 might break your system.
2874 vt.cur_default= [VT] Default cursor shape.
2875 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2876 the parameters of the <Esc>[?A;B;Cc escape sequence;
2877 see VGA-softcursor.txt. Default: 2 = underline.
2879 vt.default_blu= [VT]
2880 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2881 Change the default blue palette of the console.
2882 This is a 16-member array composed of values
2885 vt.default_grn= [VT]
2886 Format: <green0>,<green1>,<green2>,...,<green15>
2887 Change the default green palette of the console.
2888 This is a 16-member array composed of values
2891 vt.default_red= [VT]
2892 Format: <red0>,<red1>,<red2>,...,<red15>
2893 Change the default red palette of the console.
2894 This is a 16-member array composed of values
2900 Set system-wide default UTF-8 mode for all tty's.
2901 Default is 1, i.e. UTF-8 mode is enabled for all
2902 newly opened terminals.
2904 vt.global_cursor_default=
2907 Set system-wide default for whether a cursor
2908 is shown on new VTs. Default is -1,
2909 i.e. cursors will be created by default unless
2910 overridden by individual drivers. 0 will hide
2911 cursors, 1 will display them.
2913 watchdog timers [HW,WDT] For information on watchdog timers,
2914 see Documentation/watchdog/watchdog-parameters.txt
2915 or other driver-specific files in the
2916 Documentation/watchdog/ directory.
2918 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2919 default x2apic cluster mode on platforms
2922 x86_mrst_timer= [X86-32,APBT]
2923 Choose timer option for x86 Moorestown MID platform.
2924 Two valid options are apbt timer only and lapic timer
2925 plus one apbt timer for broadcast timer.
2926 x86_mrst_timer=apbt_only | lapic_and_apbt
2928 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2929 xd_geo= See header of drivers/block/xd.c.
2931 xen_emul_unplug= [HW,X86,XEN]
2932 Unplug Xen emulated devices
2933 Format: [unplug0,][unplug1]
2934 ide-disks -- unplug primary master IDE devices
2935 aux-ide-disks -- unplug non-primary-master IDE devices
2936 nics -- unplug network devices
2937 all -- unplug all emulated devices (NICs and IDE disks)
2938 unnecessary -- unplugging emulated devices is
2939 unnecessary even if the host did not respond to
2941 never -- do not unplug even if version check succeeds
2943 xirc2ps_cs= [NET,PCMCIA]
2945 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2947 ______________________________________________________________________
2951 Add more DRM drivers.
git.openpandora.org / pandora-kernel.git / blob