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 CLK Common clock infrastructure is enabled.
48 CMA Contiguous Memory Area support is enabled.
49 DRM Direct Rendering Management support is enabled.
50 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
51 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
52 EFI EFI Partitioning (GPT) is enabled
53 EIDE EIDE/ATAPI support is enabled.
54 EVM Extended Verification Module
55 FB The frame buffer device is enabled.
56 FTRACE Function tracing enabled.
57 GCOV GCOV profiling is enabled.
58 HW Appropriate hardware is enabled.
59 IA-64 IA-64 architecture is enabled.
60 IMA Integrity measurement architecture is enabled.
61 IOSCHED More than one I/O scheduler is enabled.
62 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
63 IPV6 IPv6 support is enabled.
64 ISAPNP ISA PnP code is enabled.
65 ISDN Appropriate ISDN support is enabled.
66 JOY Appropriate joystick support is enabled.
67 KGDB Kernel debugger support is enabled.
68 KVM Kernel Virtual Machine support is enabled.
69 LIBATA Libata driver is enabled
70 LP Printer support is enabled.
71 LOOP Loopback device support is enabled.
72 M68k M68k architecture is enabled.
73 These options have more detailed description inside of
74 Documentation/m68k/kernel-options.txt.
75 MDA MDA console support is enabled.
76 MIPS MIPS architecture is enabled.
77 MOUSE Appropriate mouse support is enabled.
78 MSI Message Signaled Interrupts (PCI).
79 MTD MTD (Memory Technology Device) support is enabled.
80 NET Appropriate network support is enabled.
81 NUMA NUMA support is enabled.
82 NFS Appropriate NFS support is enabled.
83 OSS OSS sound support is enabled.
84 PV_OPS A paravirtualized kernel is enabled.
85 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
86 PARISC The PA-RISC architecture is enabled.
87 PCI PCI bus support is enabled.
88 PCIE PCI Express support is enabled.
89 PCMCIA The PCMCIA subsystem is enabled.
90 PNP Plug & Play support is enabled.
91 PPC PowerPC architecture is enabled.
92 PPT Parallel port support is enabled.
93 PS2 Appropriate PS/2 support is enabled.
94 RAM RAM disk support is enabled.
95 S390 S390 architecture is enabled.
96 SCSI Appropriate SCSI support is enabled.
97 A lot of drivers have their options described inside
98 the Documentation/scsi/ sub-directory.
99 SECURITY Different security models are enabled.
100 SELINUX SELinux support is enabled.
101 APPARMOR AppArmor support is enabled.
102 SERIAL Serial support is enabled.
103 SH SuperH architecture is enabled.
104 SMP The kernel is an SMP kernel.
105 SPARC Sparc architecture is enabled.
106 SWSUSP Software suspend (hibernation) is enabled.
107 SUSPEND System suspend states are enabled.
108 TPM TPM drivers are enabled.
109 TS Appropriate touchscreen support is enabled.
110 UMS USB Mass Storage support is enabled.
111 USB USB support is enabled.
112 USBHID USB Human Interface Device support is enabled.
113 V4L Video For Linux support is enabled.
114 VMMIO Driver for memory mapped virtio devices is enabled.
115 VGA The VGA console has been enabled.
116 VT Virtual terminal support is enabled.
117 WDT Watchdog support is enabled.
118 XT IBM PC/XT MFM hard disk support is enabled.
119 X86-32 X86-32, aka i386 architecture is enabled.
120 X86-64 X86-64 architecture is enabled.
121 More X86-64 boot options can be found in
122 Documentation/x86/x86_64/boot-options.txt .
123 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
124 XEN Xen support is enabled
126 In addition, the following text indicates that the option:
128 BUGS= Relates to possible processor bugs on the said processor.
129 KNL Is a kernel start-up parameter.
130 BOOT Is a boot loader parameter.
132 Parameters denoted with BOOT are actually interpreted by the boot
133 loader, and have no meaning to the kernel directly.
134 Do not modify the syntax of boot loader parameters without extreme
135 need or coordination with <Documentation/x86/boot.txt>.
137 There are also arch-specific kernel-parameters not documented here.
138 See for example <Documentation/x86/x86_64/boot-options.txt>.
140 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
141 a trailing = on the name of any parameter states that that parameter will
142 be entered as an environment variable, whereas its absence indicates that
143 it will appear as a kernel argument readable via /proc/cmdline by programs
144 running once the system is up.
146 The number of kernel parameters is not limited, but the length of the
147 complete command line (parameters including spaces etc.) is limited to
148 a fixed number of characters. This limit depends on the architecture
149 and is between 256 and 4096 characters. It is defined in the file
150 ./include/asm/setup.h as COMMAND_LINE_SIZE.
152 Finally, the [KMG] suffix is commonly described after a number of kernel
153 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
154 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
155 bytes respectively. Such letter suffixes can also be entirely omitted.
159 Advanced Configuration and Power Interface
160 Format: { force | off | strict | noirq | rsdt }
161 force -- enable ACPI if default was off
162 off -- disable ACPI if default was on
163 noirq -- do not use ACPI for IRQ routing
164 strict -- Be less tolerant of platforms that are not
165 strictly ACPI specification compliant.
166 rsdt -- prefer RSDT over (default) XSDT
167 copy_dsdt -- copy DSDT to memory
169 See also Documentation/power/runtime_pm.txt, pci=noacpi
171 acpi_rsdp= [ACPI,EFI,KEXEC]
172 Pass the RSDP address to the kernel, mostly used
173 on machines running EFI runtime service to boot the
174 second kernel for kdump.
176 acpi_apic_instance= [ACPI, IOAPIC]
178 2: use 2nd APIC table, if available
179 1,0: use 1st APIC table
182 acpi_backlight= [HW,ACPI]
183 acpi_backlight=vendor
185 If set to vendor, prefer vendor specific driver
186 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
187 of the ACPI video.ko driver.
189 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
190 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
192 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
193 debug output. Bits in debug_layer correspond to a
194 _COMPONENT in an ACPI source file, e.g.,
195 #define _COMPONENT ACPI_PCI_COMPONENT
196 Bits in debug_level correspond to a level in
197 ACPI_DEBUG_PRINT statements, e.g.,
198 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
199 The debug_level mask defaults to "info". See
200 Documentation/acpi/debug.txt for more information about
201 debug layers and levels.
203 Enable processor driver info messages:
204 acpi.debug_layer=0x20000000
205 Enable PCI/PCI interrupt routing info messages:
206 acpi.debug_layer=0x400000
207 Enable AML "Debug" output, i.e., stores to the Debug
208 object while interpreting AML:
209 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
210 Enable all messages related to ACPI hardware:
211 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
213 Some values produce so much output that the system is
214 unusable. The "log_buf_len" parameter may be useful
215 if you need to capture more output.
217 acpi_irq_balance [HW,ACPI]
218 ACPI will balance active IRQs
221 acpi_irq_nobalance [HW,ACPI]
222 ACPI will not move active IRQs (default)
225 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
226 Format: <irq>,<irq>...
228 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
230 Format: <irq>,<irq>...
232 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
234 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
235 Format: To spoof as Windows 98: ="Microsoft Windows"
237 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
238 acpi_osi="string1" # add string1
239 acpi_osi="!string2" # remove string2
240 acpi_osi=!* # remove all strings
241 acpi_osi=! # disable all built-in OS vendor
243 acpi_osi= # disable all strings
245 'acpi_osi=!' can be used in combination with single or
246 multiple 'acpi_osi="string1"' to support specific OS
247 vendor string(s). Note that such command can only
248 affect the default state of the OS vendor strings, thus
249 it cannot affect the default state of the feature group
250 strings and the current state of the OS vendor strings,
251 specifying it multiple times through kernel command line
252 is meaningless. This command is useful when one do not
253 care about the state of the feature group strings which
254 should be controlled by the OSPM.
256 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
257 to 'acpi_osi="Windows 2000" acpi_osi=!', they all
258 can make '_OSI("Windows 2000")' TRUE.
260 'acpi_osi=' cannot be used in combination with other
261 'acpi_osi=' command lines, the _OSI method will not
262 exist in the ACPI namespace. NOTE that such command can
263 only affect the _OSI support state, thus specifying it
264 multiple times through kernel command line is also
267 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
270 'acpi_osi=!*' can be used in combination with single or
271 multiple 'acpi_osi="string1"' to support specific
272 string(s). Note that such command can affect the
273 current state of both the OS vendor strings and the
274 feature group strings, thus specifying it multiple times
275 through kernel command line is meaningful. But it may
276 still not able to affect the final state of a string if
277 there are quirks related to this string. This command
278 is useful when one want to control the state of the
279 feature group strings to debug BIOS issues related to
282 1. 'acpi_osi="Module Device" acpi_osi=!*' can make
283 '_OSI("Module Device")' FALSE.
284 2. 'acpi_osi=!* acpi_osi="Module Device"' can make
285 '_OSI("Module Device")' TRUE.
286 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
288 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
290 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
291 they all will make '_OSI("Windows 2000")' TRUE.
294 Override the pmtimer bug detection: force the kernel
295 to assume that this machine's pmtimer latches its value
296 and always returns good values.
298 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
299 Format: { level | edge | high | low }
301 acpi_serialize [HW,ACPI] force serialization of AML methods
303 acpi_skip_timer_override [HW,ACPI]
304 Recognize and ignore IRQ0/pin2 Interrupt Override.
305 For broken nForce2 BIOS resulting in XT-PIC timer.
307 acpi_sleep= [HW,ACPI] Sleep options
308 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
309 old_ordering, nonvs, sci_force_enable }
310 See Documentation/power/video.txt for information on
312 s3_beep is for debugging; it makes the PC's speaker beep
313 as soon as the kernel's real-mode entry point is called.
314 s4_nohwsig prevents ACPI hardware signature from being
315 used during resume from hibernation.
316 old_ordering causes the ACPI 1.0 ordering of the _PTS
317 control method, with respect to putting devices into
318 low power states, to be enforced (the ACPI 2.0 ordering
319 of _PTS is used by default).
320 nonvs prevents the kernel from saving/restoring the
321 ACPI NVS memory during suspend/hibernation and resume.
322 sci_force_enable causes the kernel to set SCI_EN directly
323 on resume from S1/S3 (which is against the ACPI spec,
324 but some broken systems don't work without it).
326 acpi_use_timer_override [HW,ACPI]
327 Use timer override. For some broken Nvidia NF5 boards
328 that require a timer override, but don't have HPET
330 acpi_enforce_resources= [ACPI]
331 { strict | lax | no }
332 Check for resource conflicts between native drivers
333 and ACPI OperationRegions (SystemIO and SystemMemory
334 only). IO ports and memory declared in ACPI might be
335 used by the ACPI subsystem in arbitrary AML code and
336 can interfere with legacy drivers.
337 strict (default): access to resources claimed by ACPI
338 is denied; legacy drivers trying to access reserved
339 resources will fail to bind to device using them.
340 lax: access to resources claimed by ACPI is allowed;
341 legacy drivers trying to access reserved resources
342 will bind successfully but a warning message is logged.
343 no: ACPI OperationRegions are not marked as reserved,
344 no further checks are performed.
346 add_efi_memmap [EFI; X86] Include EFI memory map in
347 kernel's map of available physical RAM.
350 { off | try_unsupported }
351 off: disable AGP support
352 try_unsupported: try to drive unsupported chipsets
353 (may crash computer or cause data corruption)
356 See Documentation/sound/alsa/alsa-parameters.txt
359 Allow the default userspace alignment fault handler
360 behaviour to be specified. Bit 0 enables warnings,
361 bit 1 enables fixups, and bit 2 sends a segfault.
363 align_va_addr= [X86-64]
364 Align virtual addresses by clearing slice [14:12] when
365 allocating a VMA at process creation time. This option
366 gives you up to 3% performance improvement on AMD F15h
367 machines (where it is enabled by default) for a
368 CPU-intensive style benchmark, and it can vary highly in
369 a microbenchmark depending on workload and compiler.
371 32: only for 32-bit processes
372 64: only for 64-bit processes
373 on: enable for both 32- and 64-bit processes
374 off: disable for both 32- and 64-bit processes
376 alloc_snapshot [FTRACE]
377 Allocate the ftrace snapshot buffer on boot up when the
378 main buffer is allocated. This is handy if debugging
379 and you need to use tracing_snapshot() on boot up, and
380 do not want to use tracing_snapshot_alloc() as it needs
381 to be done where GFP_KERNEL allocations are allowed.
383 amd_iommu= [HW,X86-64]
384 Pass parameters to the AMD IOMMU driver in the system.
386 fullflush - enable flushing of IO/TLB entries when
387 they are unmapped. Otherwise they are
388 flushed before they will be reused, which
390 off - do not initialize any AMD IOMMU found in
392 force_isolation - Force device isolation for all
393 devices. The IOMMU driver is not
394 allowed anymore to lift isolation
395 requirements as needed. This option
396 does not override iommu=pt
398 amd_iommu_dump= [HW,X86-64]
399 Enable AMD IOMMU driver option to dump the ACPI table
400 for AMD IOMMU. With this option enabled, AMD IOMMU
401 driver will print ACPI tables for AMD IOMMU during
402 IOMMU initialization.
404 amijoy.map= [HW,JOY] Amiga joystick support
405 Map of devices attached to JOY0DAT and JOY1DAT
407 See also Documentation/input/joystick.txt
409 analog.map= [HW,JOY] Analog joystick and gamepad support
410 Specifies type or capabilities of an analog joystick
411 connected to one of 16 gameports
412 Format: <type1>,<type2>,..<type16>
415 Power management functions (SPARCstation-4/5 + deriv.)
417 Disable APC CPU standby support. SPARCstation-Fox does
418 not play well with APC CPU idle - disable it if you have
419 APC and your system crashes randomly.
421 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
422 Change the output verbosity whilst booting
423 Format: { quiet (default) | verbose | debug }
424 Change the amount of debugging information output
425 when initialising the APIC and IO-APIC components.
428 See Documentation/networking/ipv6.txt.
430 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
431 Limit apic dumping. The parameter defines the maximal
432 number of local apics being dumped. Also it is possible
433 to set it to "all" by meaning -- no limit here.
434 Format: { 1 (default) | 2 | ... | all }.
435 The parameter valid if only apic=debug or
436 apic=verbose is specified.
437 Example: apic=debug show_lapic=all
439 apm= [APM] Advanced Power Management
440 See header of arch/x86/kernel/apm_32.c.
442 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
443 Format: <io>,<irq>,<nodeID>
447 atarimouse= [HW,MOUSE] Atari Mouse
449 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
450 EzKey and similar keyboards
452 atkbd.reset= [HW] Reset keyboard during initialization
454 atkbd.set= [HW] Select keyboard code set
455 Format: <int> (2 = AT (default), 3 = PS/2)
457 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
460 atkbd.softraw= [HW] Choose between synthetic and real raw mode
461 Format: <bool> (0 = real, 1 = synthetic (default))
463 atkbd.softrepeat= [HW]
464 Use software keyboard repeat
466 baycom_epp= [HW,AX25]
469 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
471 See header of drivers/net/hamradio/baycom_par.c.
473 baycom_ser_fdx= [HW,AX25]
474 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
475 Format: <io>,<irq>,<mode>[,<baud>]
476 See header of drivers/net/hamradio/baycom_ser_fdx.c.
478 baycom_ser_hdx= [HW,AX25]
479 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
480 Format: <io>,<irq>,<mode>
481 See header of drivers/net/hamradio/baycom_ser_hdx.c.
483 boot_delay= Milliseconds to delay each printk during boot.
484 Values larger than 10 seconds (10000) are changed to
488 bootmem_debug [KNL] Enable bootmem allocator debug messages.
490 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
491 bttv.radio= Most important insmod options are available as
493 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
496 bulk_remove=off [PPC] This parameter disables the use of the pSeries
497 firmware feature for flushing multiple hpte entries
500 c101= [NET] Moxa C101 synchronous serial card
502 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
503 Sometimes CPU hardware bugs make them report the cache
504 size incorrectly. The kernel will attempt work arounds
505 to fix known problems, but for some CPUs it is not
506 possible to determine what the correct size should be.
507 This option provides an override for these situations.
509 ccw_timeout_log [S390]
510 See Documentation/s390/CommonIO for details.
512 cgroup_disable= [KNL] Disable a particular controller
513 Format: {name of the controller(s) to disable}
514 {Currently supported controllers - "memory"}
516 checkreqprot [SELINUX] Set initial checkreqprot flag value.
517 Format: { "0" | "1" }
518 See security/selinux/Kconfig help text.
519 0 -- check protection applied by kernel (includes
520 any implied execute protection).
521 1 -- check protection requested by application.
522 Default value is set via a kernel config option.
523 Value can be changed at runtime via
524 /selinux/checkreqprot.
527 See Documentation/s390/CommonIO for details.
530 Keep all clocks already enabled by bootloader on,
531 even if no driver has claimed them. This is useful
532 for debug and development, but should not be
533 needed on a platform with proper driver support.
534 For more information, see Documentation/clk.txt.
536 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
538 Forces specified clocksource (if available) to be used
539 when calculating gettimeofday(). If specified
540 clocksource is not available, it defaults to PIT.
541 Format: { pit | tsc | cyclone | pmtmr }
543 clocksource= Override the default clocksource
545 Override the default clocksource and use the clocksource
546 with the name specified.
547 Some clocksource names to choose from, depending on
549 [all] jiffies (this is the base, fallback clocksource)
551 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
552 pxa_timer,timer3,32k_counter,timer0_1
554 [X86-32] pit,hpet,tsc;
555 scx200_hrt on Geode; cyclone on IBM x440
563 clearcpuid=BITNUM [X86]
564 Disable CPUID feature X for the kernel. See
565 arch/x86/include/asm/cpufeature.h for the valid bit
566 numbers. Note the Linux specific bits are not necessarily
567 stable over kernel options, but the vendor specific
569 Also note that user programs calling CPUID directly
570 or using the feature without checking anything
571 will still see it. This just prevents it from
572 being used by the kernel or shown in /proc/cpuinfo.
573 Also note the kernel might malfunction if you disable
577 Sets the size of kernel global memory area for contiguous
578 memory allocations. For more information, see
579 include/linux/dma-contiguous.h
581 cmo_free_hint= [PPC] Format: { yes | no }
582 Specify whether pages are marked as being inactive
583 when they are freed. This is used in CMO environments
584 to determine OS memory pressure for page stealing by
588 coherent_pool=nn[KMG] [ARM,KNL]
589 Sets the size of memory pool for coherent, atomic dma
590 allocations, by default set to 256K.
592 code_bytes [X86] How many bytes of object code to print
597 com20020= [HW,NET] ARCnet - COM20020 chipset
599 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
601 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
605 ARCnet - COM90xx chipset (memory-mapped buffers)
606 Format: <io>[,<irq>[,<memstart>]]
608 condev= [HW,S390] console device
611 console= [KNL] Output console device and options.
613 tty<n> Use the virtual console device <n>.
617 Use the specified serial port. The options are of
618 the form "bbbbpnf", where "bbbb" is the baud rate,
619 "p" is parity ("n", "o", or "e"), "n" is number of
620 bits, and "f" is flow control ("r" for RTS or
621 omit it). Default is "9600n8".
623 See Documentation/serial-console.txt for more
625 Documentation/networking/netconsole.txt for an
628 uart[8250],io,<addr>[,options]
629 uart[8250],mmio,<addr>[,options]
630 Start an early, polled-mode console on the 8250/16550
631 UART at the specified I/O port or MMIO address,
632 switching to the matching ttyS device later. The
633 options are the same as for ttyS, above.
634 hvc<n> Use the hypervisor console device <n>. This is for
635 both Xen and PowerPC hypervisors.
637 If the device connected to the port is not a TTY but a braille
638 device, prepend "brl," before the device type, for instance
640 For now, only VisioBraille is supported.
642 consoleblank= [KNL] The console blank (screen saver) timeout in
643 seconds. Defaults to 10*60 = 10mins. A value of 0
644 disables the blank timer.
647 [KNL] Change the default value for
648 /proc/<pid>/coredump_filter.
649 See also Documentation/filesystems/proc.txt.
651 cpuidle.off=1 [CPU_IDLE]
652 disable the cpuidle sub-system
654 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
656 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
658 crashkernel=size[KMG][@offset[KMG]]
659 [KNL] Using kexec, Linux can switch to a 'crash kernel'
660 upon panic. This parameter reserves the physical
661 memory region [offset, offset + size] for that kernel
662 image. If '@offset' is omitted, then a suitable offset
663 is selected automatically. Check
664 Documentation/kdump/kdump.txt for further details.
666 crashkernel=range1:size1[,range2:size2,...][@offset]
667 [KNL] Same as above, but depends on the memory
668 in the running system. The syntax of range is
669 start-[end] where start and end are both
670 a memory unit (amount[KMG]). See also
671 Documentation/kdump/kdump.txt for an example.
673 crashkernel=size[KMG],high
674 [KNL, x86_64] range could be above 4G. Allow kernel
675 to allocate physical memory region from top, so could
676 be above 4G if system have more than 4G ram installed.
677 Otherwise memory region will be allocated below 4G, if
679 It will be ignored if crashkernel=X is specified.
680 crashkernel=size[KMG],low
681 [KNL, x86_64] range under 4G. When crashkernel=X,high
682 is passed, kernel could allocate physical memory region
683 above 4G, that cause second kernel crash on system
684 that require some amount of low memory, e.g. swiotlb
685 requires at least 64M+32K low memory. Kernel would
686 try to allocate 72M below 4G automatically.
687 This one let user to specify own low range under 4G
688 for second kernel instead.
689 0: to disable low allocation.
690 It will be ignored when crashkernel=X,high is not used
691 or memory reserved is below 4G.
696 cs89x0_media= [HW,NET]
697 Format: { rj45 | aui | bnc }
700 See header of drivers/s390/block/dasd_devmap.c.
702 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
703 (one device per port)
704 Format: <port#>,<type>
705 See also Documentation/input/joystick-parport.txt
707 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
708 time. See Documentation/dynamic-debug-howto.txt for
709 details. Deprecated, see dyndbg.
711 debug [KNL] Enable kernel debugging (events log level).
714 [KNL] verbose self-tests
716 Print debugging info while doing the locking API
718 We default to 0 (no extra messages), setting it to
719 1 will print _a lot_ more information - normally
720 only useful to kernel developers.
722 debug_objects [KNL] Enable object debugging
725 [KNL] Disable object debugging
727 debug_guardpage_minorder=
728 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
729 parameter allows control of the order of pages that will
730 be intentionally kept free (and hence protected) by the
731 buddy allocator. Bigger value increase the probability
732 of catching random memory corruption, but reduce the
733 amount of memory for normal system use. The maximum
734 possible value is MAX_ORDER/2. Setting this parameter
735 to 1 or 2 should be enough to identify most random
736 memory corruption problems caused by bugs in kernel or
737 driver code when a CPU writes to (or reads from) a
738 random memory location. Note that there exists a class
739 of memory corruptions problems caused by buggy H/W or
740 F/W or by drivers badly programing DMA (basically when
741 memory is written at bus level and the CPU MMU is
742 bypassed) which are not detectable by
743 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
744 tracking down these problems.
746 debugpat [X86] Enable PAT debugging
748 decnet.addr= [HW,NET]
749 Format: <area>[,<node>]
750 See also Documentation/networking/decnet.txt.
753 [same as hugepagesz=] The size of the default
754 HugeTLB page size. This is the size represented by
755 the legacy /proc/ hugepages APIs, used for SHM, and
756 default size when mounting hugetlbfs filesystems.
757 Defaults to the default architecture's huge page size
761 Set number of hash buckets for dentry cache.
764 IO parameters + enable/disable command.
766 digiepca= [HW,SERIAL]
767 See drivers/char/README.epca and
768 Documentation/serial/digiepca.txt.
771 See Documentation/networking/ipv6.txt.
773 disable_ddw [PPC/PSERIES]
774 Disable Dynamic DMA Window support. Use this if
775 to workaround buggy firmware.
778 See Documentation/networking/ipv6.txt.
780 disable_mtrr_cleanup [X86]
781 The kernel tries to adjust MTRR layout from continuous
782 to discrete, to make X server driver able to add WB
783 entry later. This parameter disables that.
785 disable_mtrr_trim [X86, Intel and AMD only]
786 By default the kernel will trim any uncacheable
787 memory out of your available memory pool based on
788 MTRR settings. This parameter disables that behavior,
789 possibly causing your machine to run very slowly.
791 disable_timer_pin_1 [X86]
792 Disable PIN 1 of APIC timer
793 Can be useful to work around chipset bugs.
795 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
796 this option disables the debugging code at boot.
798 dma_debug_entries=<number>
799 This option allows to tune the number of preallocated
800 entries for DMA-API debugging code. One entry is
801 required per DMA-API allocation. Use this if the
802 DMA-API debugging code disables itself because the
803 architectural default is too low.
805 dma_debug_driver=<driver_name>
806 With this option the DMA-API debugging driver
807 filter feature can be enabled at boot time. Just
808 pass the driver to filter for as the parameter.
809 The filter can be disabled or changed to another
810 driver later using sysfs.
812 drm_kms_helper.edid_firmware=[<connector>:]<file>
813 Broken monitors, graphic adapters and KVMs may
814 send no or incorrect EDID data sets. This parameter
815 allows to specify an EDID data set in the
816 /lib/firmware directory that is used instead.
817 Generic built-in EDID data sets are used, if one of
818 edid/1024x768.bin, edid/1280x1024.bin,
819 edid/1680x1050.bin, or edid/1920x1080.bin is given
820 and no file with the same name exists. Details and
821 instructions how to build your own EDID data are
822 available in Documentation/EDID/HOWTO.txt. An EDID
823 data set will only be used for a particular connector,
824 if its name and a colon are prepended to the EDID
829 dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
830 module.dyndbg[="val"]
831 Enable debug messages at boot time. See
832 Documentation/dynamic-debug-howto.txt for details.
834 earlycon= [KNL] Output early console device and options.
835 uart[8250],io,<addr>[,options]
836 uart[8250],mmio,<addr>[,options]
837 uart[8250],mmio32,<addr>[,options]
838 Start an early, polled-mode console on the 8250/16550
839 UART at the specified I/O port or MMIO address.
840 MMIO inter-register address stride is either 8-bit
841 (mmio) or 32-bit (mmio32).
842 The options are the same as for ttyS, above.
844 earlyprintk= [X86,SH,BLACKFIN,ARM]
847 earlyprintk=serial[,ttySn[,baudrate]]
848 earlyprintk=serial[,0x...[,baudrate]]
849 earlyprintk=ttySn[,baudrate]
850 earlyprintk=dbgp[debugController#]
852 earlyprintk is useful when the kernel crashes before
853 the normal console is initialized. It is not enabled by
854 default because it has some cosmetic problems.
856 Append ",keep" to not disable it when the real console
859 Only vga or serial or usb debug port at a time.
861 Currently only ttyS0 and ttyS1 may be specified by
862 name. Other I/O ports may be explicitly specified
863 on some architectures (x86 and arm at least) by
864 replacing ttySn with an I/O port address, like this:
865 earlyprintk=serial,0x1008,115200
866 You can find the port for a given device in
867 /proc/tty/driver/serial:
868 2: uart:ST16650V2 port:00001008 irq:18 ...
870 Interaction with the standard serial driver is not
873 The VGA output is eventually overwritten by the real
876 The xen output can only be used by Xen PV guests.
878 ekgdboc= [X86,KGDB] Allow early kernel console debugging
881 This is designed to be used in conjunction with
882 the boot argument: earlyprintk=vga
885 Format: {"off" | "on" | "skip[mbr]"}
887 efi_no_storage_paranoia [EFI; X86]
888 Using this parameter you can use more than 50% of
889 your efi variable storage. Use this parameter only if
890 you are really sure that your UEFI does sane gc and
891 fulfills the spec otherwise your board may brick.
893 eisa_irq_edge= [PARISC,HW]
894 See header of drivers/parisc/eisa.c.
897 See comment before function elanfreq_setup() in
898 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
901 Format: {"cfq" | "deadline" | "noop"}
902 See Documentation/block/cfq-iosched.txt and
903 Documentation/block/deadline-iosched.txt for details.
905 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
906 Specifies physical address of start of kernel core
907 image elf header and optionally the size. Generally
908 kexec loader will pass this option to capture kernel.
909 See Documentation/kdump/kdump.txt for details.
911 enable_mtrr_cleanup [X86]
912 The kernel tries to adjust MTRR layout from continuous
913 to discrete, to make X server driver able to add WB
914 entry later. This parameter enables that.
916 enable_timer_pin_1 [X86]
917 Enable PIN 1 of APIC timer
918 Can be useful to work around chipset bugs
919 (in particular on some ATI chipsets).
920 The kernel tries to set a reasonable default.
922 enforcing [SELINUX] Set initial enforcing status.
924 See security/selinux/Kconfig help text.
925 0 -- permissive (log only, no denials).
926 1 -- enforcing (deny and log).
928 Value can be changed at runtime via /selinux/enforce.
931 Disable Error Record Serialization Table (ERST)
934 ether= [HW,NET] Ethernet cards parameters
935 This option is obsoleted by the "netdev=" option, which
936 has equivalent usage. See its documentation for details.
940 Permit 'security.evm' to be updated regardless of
941 current integrity status.
945 fail_make_request=[KNL]
946 General fault injection mechanism.
947 Format: <interval>,<probability>,<space>,<times>
948 See also Documentation/fault-injection/.
951 See Documentation/blockdev/floppy.txt.
953 force_pal_cache_flush
954 [IA-64] Avoid check_sal_cache_flush which may hang on
955 buggy SAL_CACHE_FLUSH implementations. Using this
956 parameter will force ia64_sal_cache_flush to call
957 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
960 [FTRACE] will set and start the specified tracer
961 as early as possible in order to facilitate early
964 ftrace_dump_on_oops[=orig_cpu]
965 [FTRACE] will dump the trace buffers on oops.
966 If no parameter is passed, ftrace will dump
967 buffers of all CPUs, but if you pass orig_cpu, it will
968 dump only the buffer of the CPU that triggered the
971 ftrace_filter=[function-list]
972 [FTRACE] Limit the functions traced by the function
973 tracer at boot up. function-list is a comma separated
974 list of functions. This list can be changed at run
975 time by the set_ftrace_filter file in the debugfs
978 ftrace_notrace=[function-list]
979 [FTRACE] Do not trace the functions specified in
980 function-list. This list can be changed at run time
981 by the set_ftrace_notrace file in the debugfs
984 ftrace_graph_filter=[function-list]
985 [FTRACE] Limit the top level callers functions traced
986 by the function graph tracer at boot up.
987 function-list is a comma separated list of functions
988 that can be changed at run time by the
989 set_graph_function file in the debugfs tracing directory.
992 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
993 support via parallel port (up to 5 devices per port)
994 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
995 See also Documentation/input/joystick-parport.txt
999 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
1003 gcov_persist= [GCOV] When non-zero (default), profiling data for
1004 kernel modules is saved and remains accessible via
1005 debugfs, even when the module is unloaded/reloaded.
1006 When zero, profiling data is discarded and associated
1007 debugfs files are removed at module unload time.
1009 gpt [EFI] Forces disk with valid GPT signature but
1010 invalid Protective MBR to be treated as GPT.
1012 grcan.enable0= [HW] Configuration of physical interface 0. Determines
1013 the "Enable 0" bit of the configuration register.
1016 grcan.enable1= [HW] Configuration of physical interface 1. Determines
1017 the "Enable 0" bit of the configuration register.
1020 grcan.select= [HW] Select which physical interface to use.
1023 grcan.txsize= [HW] Sets the size of the tx buffer.
1024 Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1026 grcan.rxsize= [HW] Sets the size of the rx buffer.
1027 Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1030 hashdist= [KNL,NUMA] Large hashes allocated during boot
1031 are distributed across NUMA nodes. Defaults on
1032 for 64-bit NUMA, off otherwise.
1033 Format: 0 | 1 (for off | on)
1035 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1037 hd= [EIDE] (E)IDE hard drive subsystem geometry
1038 Format: <cyl>,<head>,<sect>
1041 Disable Hardware Error Source Table (HEST) support;
1042 corresponding firmware-first mode error processing
1043 logic will be disabled.
1045 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
1046 size of <nn>. This works even on boxes that have no
1047 highmem otherwise. This also works to reduce highmem
1048 size on bigger boxes.
1050 highres= [KNL] Enable/disable high resolution timer mode.
1051 Valid parameters: "on", "off"
1055 See Documentation/isdn/README.HiSax.
1059 hpet= [X86-32,HPET] option to control HPET usage
1060 Format: { enable (default) | disable | force |
1062 disable: disable HPET and use PIT instead
1063 force: allow force enabled of undocumented chips (ICH4,
1065 verbose: show contents of HPET registers during setup
1067 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1068 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
1069 On x86-64 and powerpc, this option can be specified
1070 multiple times interleaved with hugepages= to reserve
1071 huge pages of different sizes. Valid pages sizes on
1072 x86-64 are 2M (when the CPU supports "pse") and 1G
1073 (when the CPU supports the "pdpe1gb" cpuinfo flag)
1074 Note that 1GB pages can only be allocated at boot time
1075 using hugepages= and not freed afterwards.
1077 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
1078 terminal devices. Valid values: 0..8
1079 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1080 If specified, z/VM IUCV HVC accepts connections
1081 from listed z/VM user IDs only.
1083 hwthread_map= [METAG] Comma-separated list of Linux cpu id to
1084 hardware thread id mappings.
1085 Format: <cpu>:<hwthread>
1088 Do not unregister boot console at start. This is only
1089 useful for debugging when something happens in the window
1090 between unregistering the boot console and initializing
1093 i2c_bus= [HW] Override the default board specific I2C bus speed
1094 or register an additional I2C bus that is not
1095 registered from board initialization code.
1099 i8042.debug [HW] Toggle i8042 debug mode
1100 i8042.direct [HW] Put keyboard port into non-translated mode
1101 i8042.dumbkbd [HW] Pretend that controller can only read data from
1102 keyboard and cannot control its state
1103 (Don't attempt to blink the leds)
1104 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
1105 i8042.nokbd [HW] Don't check/create keyboard port
1106 i8042.noloop [HW] Disable the AUX Loopback command while probing
1108 i8042.nomux [HW] Don't check presence of an active multiplexing
1110 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1112 i8042.notimeout [HW] Ignore timeout condition signalled by controller
1113 i8042.reset [HW] Reset the controller during init and cleanup
1114 i8042.unlock [HW] Unlock (ignore) the keylock
1118 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
1119 indicates that the driver is running on unsupported
1121 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
1122 does not match list of supported models.
1124 [HW] Report power status in /proc/i8k
1125 (disabled by default)
1126 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
1129 i915.invert_brightness=
1130 [DRM] Invert the sense of the variable that is used to
1131 set the brightness of the panel backlight. Normally a
1132 brightness value of 0 indicates backlight switched off,
1133 and the maximum of the brightness value sets the backlight
1134 to maximum brightness. If this parameter is set to 0
1135 (default) and the machine requires it, or this parameter
1136 is set to 1, a brightness value of 0 sets the backlight
1137 to maximum brightness, and the maximum of the brightness
1138 value switches the backlight off.
1139 -1 -- never invert brightness
1140 0 -- machine default
1141 1 -- force brightness inversion
1144 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1146 ide-core.nodma= [HW] (E)IDE subsystem
1147 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1148 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1149 .cdrom .chs .ignore_cable are additional options
1150 See Documentation/ide/ide.txt.
1152 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1153 Claim all unknown PCI IDE storage controllers.
1156 Format: idle=poll, idle=halt, idle=nomwait
1157 Poll forces a polling idle loop that can slightly
1158 improve the performance of waking up a idle CPU, but
1159 will use a lot of power and make the system run hot.
1161 idle=halt: Halt is forced to be used for CPU idle.
1162 In such case C2/C3 won't be used again.
1163 idle=nomwait: Disable mwait for CPU C-states
1165 ignore_loglevel [KNL]
1166 Ignore loglevel setting - this will print /all/
1167 kernel messages to the console. Useful for debugging.
1168 We also add it as printk module parameter, so users
1169 could change it dynamically, usually by
1170 /sys/module/printk/parameters/ignore_loglevel.
1172 ihash_entries= [KNL]
1173 Set number of hash buckets for inode cache.
1175 ima_appraise= [IMA] appraise integrity measurements
1176 Format: { "off" | "enforce" | "fix" }
1179 ima_appraise_tcb [IMA]
1180 The builtin appraise policy appraises all files
1184 Format: { "sha1" | "md5" }
1188 Load a policy which meets the needs of the Trusted
1189 Computing Base. This means IMA will measure all
1190 programs exec'd, files mmap'd for exec, and all files
1191 opened for read by uid=0.
1195 Run specified binary instead of /sbin/init as init
1198 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1199 for working out where the kernel is dying during
1202 initrd= [BOOT] Specify the location of the initial ramdisk
1204 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1207 int_pln_enable [x86] Enable power limit notification interrupt
1209 integrity_audit=[IMA]
1210 Format: { "0" | "1" }
1211 0 -- basic integrity auditing messages. (Default)
1212 1 -- additional integrity auditing messages.
1214 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1216 Enable intel iommu driver.
1218 Disable intel iommu driver.
1219 igfx_off [Default Off]
1220 By default, gfx is mapped as normal device. If a gfx
1221 device has a dedicated DMAR unit, the DMAR unit is
1222 bypassed by not enabling DMAR with this option. In
1223 this case, gfx device will use physical address for
1226 With this option iommu will not optimize to look
1227 for io virtual address below 32-bit forcing dual
1228 address cycle on pci bus for cards supporting greater
1229 than 32-bit addressing. The default is to look
1230 for translation below 32-bit and if not available
1231 then look in the higher range.
1232 strict [Default Off]
1233 With this option on every unmap_single operation will
1234 result in a hardware IOTLB flush operation as opposed
1235 to batching them for performance.
1236 sp_off [Default Off]
1237 By default, super page will be supported if Intel IOMMU
1238 has the capability. With this option, super page will
1241 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1242 0 disables intel_idle and fall back on acpi_idle.
1243 1 to 6 specify maximum depth of C-state.
1247 Do not enable intel_pstate as the default
1248 scaling driver for the supported processors
1250 intremap= [X86-64, Intel-IOMMU]
1251 on enable Interrupt Remapping (default)
1252 off disable Interrupt Remapping
1253 nosid disable Source ID checking
1255 BIOS x2APIC opt-out request will be ignored
1257 iomem= Disable strict checking of access to MMIO memory
1258 strict regions from userspace.
1275 io7= [HW] IO7 for Marvel based alpha systems
1276 See comment before marvel_specify_io7 in
1277 arch/alpha/kernel/core_marvel.c.
1279 io_delay= [X86] I/O delay method
1281 Standard port 0x80 based delay
1283 Alternate port 0xed based delay (needed on some systems)
1285 Simple two microseconds delay
1290 See Documentation/filesystems/nfs/nfsroot.txt.
1292 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1293 See comment before ip2_setup() in
1294 drivers/char/ip2/ip2base.c.
1297 When an interrupt is not handled search all handlers
1298 for it. Intended to get systems with badly broken
1302 When an interrupt is not handled search all handlers
1303 for it. Also check all handlers each timer
1304 interrupt. Intended to get systems with badly broken
1308 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1310 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1312 <cpu number>,...,<cpu number>
1314 <cpu number>-<cpu number>
1315 (must be a positive range in ascending order)
1317 <cpu number>,...,<cpu number>-<cpu number>
1319 This option can be used to specify one or more CPUs
1320 to isolate from the general SMP balancing and scheduling
1321 algorithms. You can move a process onto or off an
1322 "isolated" CPU via the CPU affinity syscalls or cpuset.
1323 <cpu number> begins at 0 and the maximum value is
1324 "number of CPUs in system - 1".
1326 This option is the preferred way to isolate CPUs. The
1327 alternative -- manually setting the CPU mask of all
1328 tasks in the system -- can cause problems and
1329 suboptimal load balancer performance.
1333 ivrs_ioapic [HW,X86_64]
1334 Provide an override to the IOAPIC-ID<->DEVICE-ID
1335 mapping provided in the IVRS ACPI table. For
1336 example, to map IOAPIC-ID decimal 10 to
1337 PCI device 00:14.0 write the parameter as:
1338 ivrs_ioapic[10]=00:14.0
1340 ivrs_hpet [HW,X86_64]
1341 Provide an override to the HPET-ID<->DEVICE-ID
1342 mapping provided in the IVRS ACPI table. For
1343 example, to map HPET-ID decimal 0 to
1344 PCI device 00:14.0 write the parameter as:
1345 ivrs_hpet[0]=00:14.0
1347 js= [HW,JOY] Analog joystick
1348 See Documentation/input/joystick.txt.
1352 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1353 specifies the amount of memory usable by the kernel
1354 for non-movable allocations. The requested amount is
1355 spread evenly throughout all nodes in the system. The
1356 remaining memory in each node is used for Movable
1357 pages. In the event, a node is too small to have both
1358 kernelcore and Movable pages, kernelcore pages will
1359 take priority and other nodes will have a larger number
1360 of kernelcore pages. The Movable zone is used for the
1361 allocation of pages that may be reclaimed or moved
1362 by the page migration subsystem. This means that
1363 HugeTLB pages may not be allocated from this zone.
1364 Note that allocations like PTEs-from-HighMem still
1365 use the HighMem zone if it exists, and the Normal
1366 zone if it does not.
1368 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1369 Format: <Controller#>[,poll interval]
1370 The controller # is the number of the ehci usb debug
1371 port as it is probed via PCI. The poll interval is
1372 optional and is the number seconds in between
1373 each poll cycle to the debug port in case you need
1374 the functionality for interrupting the kernel with
1375 gdb or control-c on the dbgp connection. When
1376 not using this parameter you use sysrq-g to break into
1377 the kernel debugger.
1379 kgdboc= [KGDB,HW] kgdb over consoles.
1380 Requires a tty driver that supports console polling,
1381 or a supported polling keyboard driver (non-usb).
1382 Serial only format: <serial_device>[,baud]
1383 keyboard only format: kbd
1384 keyboard and serial format: kbd,<serial_device>[,baud]
1385 Optional Kernel mode setting:
1386 kms, kbd format: kms,kbd
1387 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1389 kgdbwait [KGDB] Stop kernel execution and enter the
1390 kernel debugger at the earliest opportunity.
1392 kmac= [MIPS] korina ethernet MAC address.
1393 Configure the RouterBoard 532 series on-chip
1394 Ethernet adapter MAC address.
1396 kmemleak= [KNL] Boot-time kmemleak enable/disable
1397 Valid arguments: on, off
1400 kstack=N [X86] Print N words from the kernel stack
1403 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1404 Default is 0 (don't ignore, but inject #GP)
1406 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1410 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1411 Default is 1 (enabled)
1413 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1415 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1417 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1418 (virtualized MMU) support on capable Intel chips.
1419 Default is 1 (enabled)
1421 kvm-intel.emulate_invalid_guest_state=
1422 [KVM,Intel] Enable emulation of invalid guest states
1423 Default is 0 (disabled)
1425 kvm-intel.flexpriority=
1426 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1427 Default is 1 (enabled)
1430 [KVM,Intel] Enable VMX nesting (nVMX).
1431 Default is 0 (disabled)
1433 kvm-intel.unrestricted_guest=
1434 [KVM,Intel] Disable unrestricted guest feature
1435 (virtualized real and unpaged mode) on capable
1436 Intel chips. Default is 1 (enabled)
1438 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1439 feature (tagged TLBs) on capable Intel chips.
1440 Default is 1 (enabled)
1446 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1449 lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
1450 value for LAPIC timer one-shot implementation. Default
1451 back to the programmable timer unit in the LAPIC.
1453 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1456 libata.dma= [LIBATA] DMA control
1457 libata.dma=0 Disable all PATA and SATA DMA
1458 libata.dma=1 PATA and SATA Disk DMA only
1459 libata.dma=2 ATAPI (CDROM) DMA only
1460 libata.dma=4 Compact Flash DMA only
1461 Combinations also work, so libata.dma=3 enables DMA
1462 for disks and CDROMs, but not CFs.
1464 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1465 libata.ignore_hpa=0 keep BIOS limits (default)
1466 libata.ignore_hpa=1 ignore limits, using full disk
1468 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1472 libata.force= [LIBATA] Force configurations. The format is comma
1473 separated list of "[ID:]VAL" where ID is
1474 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1475 matching port, link or device. Basically, it matches
1476 the ATA ID string printed on console by libata. If
1477 the whole ID part is omitted, the last PORT and DEVICE
1478 values are used. If ID hasn't been specified yet, the
1479 configuration applies to all ports, links and devices.
1481 If only DEVICE is omitted, the parameter applies to
1482 the port and all links and devices behind it. DEVICE
1483 number of 0 either selects the first device or the
1484 first fan-out link behind PMP device. It does not
1485 select the host link. DEVICE number of 15 selects the
1486 host link and device attached to it.
1488 The VAL specifies the configuration to force. As long
1489 as there's no ambiguity shortcut notation is allowed.
1490 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1491 The following configurations can be forced.
1493 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1494 Any ID with matching PORT is used.
1496 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1498 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1499 udma[/][16,25,33,44,66,100,133] notation is also
1502 * [no]ncq: Turn on or off NCQ.
1504 * nohrst, nosrst, norst: suppress hard, soft
1507 * rstonce: only attempt one reset during
1508 hot-unplug link recovery
1510 * dump_id: dump IDENTIFY data.
1512 * atapi_dmadir: Enable ATAPI DMADIR bridge support
1514 If there are multiple matching configurations changing
1515 the same attribute, the last one is used.
1517 memblock=debug [KNL] Enable memblock debug messages.
1519 load_ramdisk= [RAM] List of ramdisks to load from floppy
1520 See Documentation/blockdev/ramdisk.txt.
1522 lockd.nlm_grace_period=P [NFS] Assign grace period.
1525 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1528 lockd.nlm_timeout=T [NFS] Assign timeout value.
1531 lockd.nlm_udpport=M [NFS] Assign UDP port.
1534 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1537 loglevel= All Kernel Messages with a loglevel smaller than the
1538 console loglevel will be printed to the console. It can
1539 also be changed with klogd or other programs. The
1540 loglevels are defined as follows:
1542 0 (KERN_EMERG) system is unusable
1543 1 (KERN_ALERT) action must be taken immediately
1544 2 (KERN_CRIT) critical conditions
1545 3 (KERN_ERR) error conditions
1546 4 (KERN_WARNING) warning conditions
1547 5 (KERN_NOTICE) normal but significant condition
1548 6 (KERN_INFO) informational
1549 7 (KERN_DEBUG) debug-level messages
1551 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1552 in bytes. n must be a power of two. The default
1553 size is set in the kernel config file.
1555 logo.nologo [FB] Disables display of the built-in Linux logo.
1556 This may be used to provide more screen space for
1557 kernel log messages and is useful when debugging
1558 kernel boot problems.
1560 lp=0 [LP] Specify parallel ports to use, e.g,
1561 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1562 lp=reset first parallel port). 'lp=0' disables the
1563 lp=auto printer driver. 'lp=reset' (which can be
1564 specified in addition to the ports) causes
1565 attached printers to be reset. Using
1566 lp=port1,port2,... specifies the parallel ports
1567 to associate lp devices with, starting with
1568 lp0. A port specification may be 'none' to skip
1569 that lp device, or a parport name such as
1570 'parport0'. Specifying 'lp=auto' instead of a
1571 port specification list means that device IDs
1572 from each port should be examined, to see if
1573 an IEEE 1284-compliant printer is attached; if
1574 so, the driver will manage that printer.
1575 See also header of drivers/char/lp.c.
1578 Sets loops_per_jiffy to given constant, thus avoiding
1579 time-consuming boot-time autodetection (up to 250 ms per
1580 CPU). 0 enables autodetection (default). To determine
1581 the correct value for your kernel, boot with normal
1582 autodetection and see what value is printed. Note that
1583 on SMP systems the preset will be applied to all CPUs,
1584 which is likely to cause problems if your CPUs need
1585 significantly divergent settings. An incorrect value
1586 will cause delays in the kernel to be wrong, leading to
1587 unpredictable I/O errors and other breakage. Although
1588 unlikely, in the extreme case this might damage your
1592 Format: <io>,<irq>,<dma>
1594 machvec= [IA-64] Force the use of a particular machine-vector
1595 (machvec) in a generic kernel.
1596 Example: machvec=hpzx1_swiotlb
1598 machtype= [Loongson] Share the same kernel image file between different
1600 Example: machtype=lemote-yeeloong-2f-7inch
1602 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1603 than or equal to this physical address is ignored.
1605 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1606 should make use of. maxcpus=n : n >= 0 limits the
1607 kernel to using 'n' processors. n=0 is a special case,
1608 it is equivalent to "nosmp", which also disables
1611 max_loop= [LOOP] The number of loop block devices that get
1612 (loop.max_loop) unconditionally pre-created at init time. The default
1613 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1614 of statically allocating a predefined number, loop
1615 devices can be requested on-demand with the
1616 /dev/loop-control interface.
1618 mce [X86-32] Machine Check Exception
1620 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1622 md= [HW] RAID subsystems devices and level
1623 See Documentation/md.txt.
1626 Format: <first>,<last>
1627 Specifies range of consoles to be captured by the MDA.
1629 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1630 Amount of memory to be used when the kernel is not able
1631 to see the whole system memory or for test.
1632 [X86] Work as limiting max address. Use together
1633 with memmap= to avoid physical address space collisions.
1634 Without memmap= PCI devices could be placed at addresses
1635 belonging to unused RAM.
1637 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1641 [KNL,SH] Allow user to override the default size for
1642 per-device physically contiguous DMA buffers.
1644 memmap=exactmap [KNL,X86] Enable setting of an exact
1645 E820 memory map, as specified by the user.
1646 Such memmap=exactmap lines can be constructed based on
1647 BIOS output or other requirements. See the memmap=nn@ss
1650 memmap=nn[KMG]@ss[KMG]
1651 [KNL] Force usage of a specific region of memory
1652 Region of memory to be used, from ss to ss+nn.
1654 memmap=nn[KMG]#ss[KMG]
1655 [KNL,ACPI] Mark specific memory as ACPI data.
1656 Region of memory to be used, from ss to ss+nn.
1658 memmap=nn[KMG]$ss[KMG]
1659 [KNL,ACPI] Mark specific memory as reserved.
1660 Region of memory to be used, from ss to ss+nn.
1661 Example: Exclude memory from 0x18690000-0x1869ffff
1662 memmap=64K$0x18690000
1664 memmap=0x10000$0x18690000
1666 memory_corruption_check=0/1 [X86]
1667 Some BIOSes seem to corrupt the first 64k of
1668 memory when doing things like suspend/resume.
1669 Setting this option will scan the memory
1670 looking for corruption. Enabling this will
1671 both detect corruption and prevent the kernel
1672 from using the memory being corrupted.
1673 However, its intended as a diagnostic tool; if
1674 repeatable BIOS-originated corruption always
1675 affects the same memory, you can use memmap=
1676 to prevent the kernel from using that memory.
1678 memory_corruption_check_size=size [X86]
1679 By default it checks for corruption in the low
1680 64k, making this memory unavailable for normal
1681 use. Use this parameter to scan for
1682 corruption in more or less memory.
1684 memory_corruption_check_period=seconds [X86]
1685 By default it checks for corruption every 60
1686 seconds. Use this parameter to check at some
1687 other rate. 0 disables periodic checking.
1689 memtest= [KNL,X86] Enable memtest
1691 default : 0 <disable>
1692 Specifies the number of memtest passes to be
1693 performed. Each pass selects another test
1694 pattern from a given set of patterns. Memtest
1695 fills the memory with this pattern, validates
1696 memory contents and reserves bad memory
1697 regions that are detected.
1699 meye.*= [HW] Set MotionEye Camera parameters
1700 See Documentation/video4linux/meye.txt.
1702 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1703 Multi-Function General Purpose Timers on AMD Geode
1706 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1707 the BIOS has incorrectly applied a workaround. TinyBIOS
1708 version 0.98 is known to be affected, 0.99 fixes the
1709 problem by letting the user disable the workaround.
1713 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1714 physical address is ignored.
1716 mini2440= [ARM,HW,KNL]
1717 Format:[0..2][b][c][t]
1719 MINI2440 configuration specification:
1720 0 - The attached screen is the 3.5" TFT
1721 1 - The attached screen is the 7" TFT
1722 2 - The VGA Shield is attached (1024x768)
1723 Leaving out the screen size parameter will not load
1724 the TFT driver, and the framebuffer will be left
1726 b - Enable backlight. The TFT backlight pin will be
1727 linked to the kernel VESA blanking code and a GPIO
1728 LED. This parameter is not necessary when using the
1730 c - Enable the s3c camera interface.
1731 t - Reserved for enabling touchscreen support. The
1732 touchscreen support is not enabled in the mainstream
1733 kernel as of 2.6.30, a preliminary port can be found
1734 in the "bleeding edge" mini2440 support kernel at
1735 http://repo.or.cz/w/linux-2.6/mini2440.git
1738 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1739 parameter allows control of the logging verbosity for
1740 the additional memory initialisation checks. A value
1741 of 0 disables mminit logging and a level of 4 will
1742 log everything. Information is printed at KERN_DEBUG
1743 so loglevel=8 may also need to be specified.
1746 [KNL] When CONFIG_MODULE_SIG is set, this means that
1747 modules without (valid) signatures will fail to load.
1748 Note that if CONFIG_MODULE_SIG_FORCE is set, that
1749 is always true, so this option does nothing.
1752 [MOUSE] Maximum time between finger touching and
1753 leaving touchpad surface for touch to be considered
1754 a tap and be reported as a left button click (for
1755 touchpads working in absolute mode only).
1757 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1758 reporting absolute coordinates, such as tablets
1759 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1760 reporting absolute coordinates, such as tablets
1762 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1763 is similar to kernelcore except it specifies the
1764 amount of memory used for migratable allocations.
1765 If both kernelcore and movablecore is specified,
1766 then kernelcore will be at *least* the specified
1767 value but may be more. If movablecore on its own
1768 is specified, the administrator must be careful
1769 that the amount of memory usable for all allocations
1772 MTD_Partition= [MTD]
1773 Format: <name>,<region-number>,<size>,<offset>
1775 MTD_Region= [MTD] Format:
1776 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1779 See drivers/mtd/cmdlinepart.c.
1781 multitce=off [PPC] This parameter disables the use of the pSeries
1782 firmware feature for updating multiple TCE entries
1785 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1787 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1789 boundary - index of last SLC block on Flex-OneNAND.
1790 The remaining blocks are configured as MLC blocks.
1791 lock - Configure if Flex-OneNAND boundary should be locked.
1792 Once locked, the boundary cannot be changed.
1793 1 indicates lock status, 0 indicates unlock status.
1796 ARM/S3C2412 JIVE boot control
1798 See arch/arm/mach-s3c2412/mach-jive.c
1800 mtouchusb.raw_coordinates=
1801 [HW] Make the MicroTouch USB driver use raw coordinates
1802 ('y', default) or cooked coordinates ('n')
1804 mtrr_chunk_size=nn[KMG] [X86]
1805 used for mtrr cleanup. It is largest continuous chunk
1806 that could hold holes aka. UC entries.
1808 mtrr_gran_size=nn[KMG] [X86]
1809 Used for mtrr cleanup. It is granularity of mtrr block.
1811 Large value could prevent small alignment from
1814 mtrr_spare_reg_nr=n [X86]
1816 Range: 0,7 : spare reg number
1818 Used for mtrr cleanup. It is spare mtrr entries number.
1819 Set to 2 or more if your graphical card needs more.
1821 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1823 netdev= [NET] Network devices parameters
1824 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1825 Note that mem_start is often overloaded to mean
1826 something different and driver-specific.
1827 This usage is only documented in each driver source
1831 [NETFILTER] Enable connection tracking flow accounting
1832 0 to disable accounting
1833 1 to enable accounting
1836 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1837 See Documentation/filesystems/nfs/nfsroot.txt.
1839 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1840 See Documentation/filesystems/nfs/nfsroot.txt.
1842 nfsrootdebug [NFS] enable nfsroot debugging messages.
1843 See Documentation/filesystems/nfs/nfsroot.txt.
1845 nfs.callback_tcpport=
1846 [NFS] set the TCP port on which the NFSv4 callback
1847 channel should listen.
1850 [NFS] sets the pathname to the program which is used
1851 to update the NFS client cache entries.
1853 nfs.cache_getent_timeout=
1854 [NFS] sets the timeout after which an attempt to
1855 update a cache entry is deemed to have failed.
1857 nfs.idmap_cache_timeout=
1858 [NFS] set the maximum lifetime for idmapper cache
1862 [NFS] enable 64-bit inode numbers.
1863 If zero, the NFS client will fake up a 32-bit inode
1864 number for the readdir() and stat() syscalls instead
1865 of returning the full 64-bit number.
1866 The default is to return 64-bit inode numbers.
1868 nfs.max_session_slots=
1869 [NFSv4.1] Sets the maximum number of session slots
1870 the client will attempt to negotiate with the server.
1871 This limits the number of simultaneous RPC requests
1872 that the client can send to the NFSv4.1 server.
1873 Note that there is little point in setting this
1874 value higher than the max_tcp_slot_table_limit.
1876 nfs.nfs4_disable_idmapping=
1877 [NFSv4] When set to the default of '1', this option
1878 ensures that both the RPC level authentication
1879 scheme and the NFS level operations agree to use
1880 numeric uids/gids if the mount is using the
1881 'sec=sys' security flavour. In effect it is
1882 disabling idmapping, which can make migration from
1883 legacy NFSv2/v3 systems to NFSv4 easier.
1884 Servers that do not support this mode of operation
1885 will be autodetected by the client, and it will fall
1886 back to using the idmapper.
1887 To turn off this behaviour, set the value to '0'.
1889 [NFS4] Specify an additional fixed unique ident-
1890 ification string that NFSv4 clients can insert into
1891 their nfs_client_id4 string. This is typically a
1892 UUID that is generated at system install time.
1894 nfs.send_implementation_id =
1895 [NFSv4.1] Send client implementation identification
1896 information in exchange_id requests.
1897 If zero, no implementation identification information
1899 The default is to send the implementation identification
1902 nfs.recover_lost_locks =
1903 [NFSv4] Attempt to recover locks that were lost due
1904 to a lease timeout on the server. Please note that
1905 doing this risks data corruption, since there are
1906 no guarantees that the file will remain unchanged
1907 after the locks are lost.
1908 If you want to enable the kernel legacy behaviour of
1909 attempting to recover these locks, then set this
1911 The default parameter value of '0' causes the kernel
1912 not to attempt recovery of lost locks.
1914 nfsd.nfs4_disable_idmapping=
1915 [NFSv4] When set to the default of '1', the NFSv4
1916 server will return only numeric uids and gids to
1917 clients using auth_sys, and will accept numeric uids
1918 and gids from such clients. This is intended to ease
1919 migration from NFSv2/v3.
1921 objlayoutdriver.osd_login_prog=
1922 [NFS] [OBJLAYOUT] sets the pathname to the program which
1923 is used to automatically discover and login into new
1924 osd-targets. Please see:
1925 Documentation/filesystems/pnfs.txt for more explanations
1927 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1928 when a NMI is triggered.
1929 Format: [state][,regs][,debounce][,die]
1931 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1932 Format: [panic,][nopanic,][num]
1934 0 - turn nmi_watchdog off
1935 When panic is specified, panic when an NMI watchdog
1936 timeout occurs (or 'nopanic' to override the opposite
1938 This is useful when you use a panic=... timeout and
1939 need the box quickly up again.
1941 netpoll.carrier_timeout=
1942 [NET] Specifies amount of time (in seconds) that
1943 netpoll should wait for a carrier. By default netpoll
1946 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1947 emulation library even if a 387 maths coprocessor
1951 [HW] Never suspend the console
1952 Disable suspending of consoles during suspend and
1953 hibernate operations. Once disabled, debugging
1954 messages can reach various consoles while the rest
1955 of the system is being put to sleep (ie, while
1956 debugging driver suspend/resume hooks). This may
1957 not work reliably with all consoles, but is known
1958 to work with serial and VGA consoles.
1959 To facilitate more flexible debugging, we also add
1960 console_suspend, a printk module parameter to control
1961 it. Users could use console_suspend (usually
1962 /sys/module/printk/parameters/console_suspend) to
1963 turn on/off it dynamically.
1965 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1966 caches in the slab allocator. Saves per-node memory,
1967 but will impact performance.
1971 noapic [SMP,APIC] Tells the kernel to not make use of any
1972 IOAPICs that may be present in the system.
1974 noautogroup Disable scheduler automatic task group creation.
1976 nobats [PPC] Do not use BATs for mapping kernel lowmem
1977 on "Classic" PPC cores.
1981 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1983 nodelayacct [KNL] Disable per-task delay accounting
1985 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1987 nodsp [SH] Disable hardware DSP at boot time.
1989 noefi [X86] Disable EFI runtime services support.
1994 On X86-32 available only on PAE configured kernels.
1995 noexec=on: enable non-executable mappings (default)
1996 noexec=off: disable non-executable mappings
1999 Disable SMAP (Supervisor Mode Access Prevention)
2000 even if it is supported by processor.
2003 Disable SMEP (Supervisor Mode Execution Prevention)
2004 even if it is supported by processor.
2007 This affects only 32-bit executables.
2008 noexec32=on: enable non-executable mappings (default)
2009 read doesn't imply executable mappings
2010 noexec32=off: disable non-executable mappings
2011 read implies executable mappings
2013 nofpu [SH] Disable hardware FPU at boot time.
2015 nofxsr [BUGS=X86-32] Disables x86 floating point extended
2016 register save and restore. The kernel will only save
2017 legacy floating-point registers on task switch.
2019 noxsave [BUGS=X86] Disables x86 extended register state save
2020 and restore using xsave. The kernel will fallback to
2021 enabling legacy floating-point and sse state.
2024 on enable eager fpu restore
2025 off disable eager fpu restore
2026 auto selects the default scheme, which automatically
2027 enables eagerfpu restore for xsaveopt.
2029 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2030 wfi(ARM) instruction doesn't work correctly and not to
2031 use it. This is also useful when using JTAG debugger.
2033 no_file_caps Tells the kernel not to honor file capabilities. The
2034 only way then for a file to be executed with privilege
2035 is to be setuid root or executed by root.
2037 nohalt [IA-64] Tells the kernel not to use the power saving
2038 function PAL_HALT_LIGHT when idle. This increases
2039 power-consumption. On the positive side, it reduces
2040 interrupt wake-up latency, which may improve performance
2041 in certain environments such as networked servers or
2044 nohz= [KNL] Boottime enable/disable dynamic ticks
2045 Valid arguments: on, off
2048 nohz_full= [KNL,BOOT]
2049 In kernels built with CONFIG_NO_HZ_FULL=y, set
2050 the specified list of CPUs whose tick will be stopped
2051 whenever possible. The boot CPU will be forced outside
2052 the range to maintain the timekeeping.
2053 The CPUs in this range must also be included in the
2056 noiotrap [SH] Disables trapped I/O port accesses.
2058 noirqdebug [X86-32] Disables the code which attempts to detect and
2059 disable unhandled interrupt sources.
2061 no_timer_check [X86,APIC] Disables the code which tests for
2062 broken timer IRQ sources.
2064 noisapnp [ISAPNP] Disables ISA PnP code.
2066 noinitrd [RAM] Tells the kernel not to load any configured
2069 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
2071 [Deprecated - use intremap=off]
2075 nojitter [IA-64] Disables jitter checking for ITC timers.
2077 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
2079 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
2082 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
2083 steal time is computed, but won't influence scheduler
2086 nolapic [X86-32,APIC] Do not enable or use the local APIC.
2088 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
2090 noltlbs [PPC] Do not use large page/tlb entries for kernel
2091 lowmem mapping on PPC40x.
2093 nomca [IA-64] Disable machine check abort handling
2095 nomce [X86-32] Machine Check Exception
2097 nomfgpt [X86-32] Disable Multi-Function General Purpose
2098 Timer usage (for AMD Geode machines).
2100 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
2101 shutdown the other cpus. Instead use the REBOOT_VECTOR
2104 nomodule Disable module load
2106 nopat [X86] Disable PAT (page attribute table extension of
2107 pagetables) support.
2109 norandmaps Don't use address space randomization. Equivalent to
2110 echo 0 > /proc/sys/kernel/randomize_va_space
2112 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
2114 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
2115 with UP alternatives
2117 nordrand [X86] Disable the direct use of the RDRAND
2118 instruction even if it is supported by the
2119 processor. RDRAND is still available to user
2122 noresume [SWSUSP] Disables resume and restores original swap
2125 no-scroll [VGA] Disables scrollback.
2126 This is required for the Braillex ib80-piezo Braille
2127 reader made by F.H. Papenmeier (Germany).
2131 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
2133 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
2134 and disable the IO APIC. legacy for "maxcpus=0".
2136 nosoftlockup [KNL] Disable the soft-lockup detector.
2138 nosync [HW,M68K] Disables sync negotiation for all devices.
2140 notsc [BUGS=X86-32] Disable Time Stamp Counter
2142 nousb [USB] Disable the USB subsystem
2144 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
2148 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
2150 cpu0_hotplug [X86] Turn on CPU0 hotplug feature when
2151 CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2152 Some features depend on CPU0. Known dependencies are:
2153 1. Resume from suspend/hibernate depends on CPU0.
2154 Suspend/hibernate will fail if CPU0 is offline and you
2155 need to online CPU0 before suspend/hibernate.
2156 2. PIC interrupts also depend on CPU0. CPU0 can't be
2157 removed if a PIC interrupt is detected.
2158 It's said poweroff/reboot may depend on CPU0 on some
2159 machines although I haven't seen such issues so far
2160 after CPU0 is offline on a few tested machines.
2161 If the dependencies are under your control, you can
2162 turn on cpu0_hotplug.
2164 nptcg= [IA-64] Override max number of concurrent global TLB
2165 purges which is reported from either PAL_VM_SUMMARY or
2168 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
2169 could support. nr_cpus=n : n >= 1 limits the kernel to
2170 supporting 'n' processors. Later in runtime you can not
2171 use hotplug cpu feature to put more cpu back to online.
2172 just like you compile the kernel NR_CPUS=n
2174 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
2176 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
2177 Allowed values are enable and disable
2179 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2180 one of ['zone', 'node', 'default'] can be specified
2181 This can be set from sysctl after boot.
2182 See Documentation/sysctl/vm.txt for details.
2184 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
2185 See Documentation/debugging-via-ohci1394.txt for more
2188 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2189 Rather than timing out after 20 ms if an EC
2190 command is not properly ACKed, override the length
2191 of the timeout. We have interrupts disabled while
2192 waiting for the ACK, so if this is set too high
2193 interrupts *may* be lost!
2195 omap_mux= [OMAP] Override bootloader pin multiplexing.
2196 Format: <mux_mode0.mode_name=value>...
2197 For example, to override I2C bus2:
2198 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2200 oprofile.timer= [HW]
2201 Use timer interrupt instead of performance counters
2203 oprofile.cpu_type= Force an oprofile cpu type
2204 This might be useful if you have an older oprofile
2205 userland or if you want common events.
2206 Format: { arch_perfmon }
2207 arch_perfmon: [X86] Force use of architectural
2208 perfmon on Intel CPUs instead of the
2209 CPU specific event set.
2210 timer: [X86] Force use of architectural NMI
2211 timer mode (see also oprofile.timer
2212 for generic hr timer mode)
2213 [s390] Force legacy basic mode sampling
2214 (report cpu_type "timer")
2216 oops=panic Always panic on oopses. Default is to just kill the
2217 process, but there is a small probability of
2218 deadlocking the machine.
2219 This will also cause panics on machine check exceptions.
2220 Useful together with panic=30 to trigger a reboot.
2223 See Documentation/sound/oss/oss-parameters.txt
2225 panic= [KNL] Kernel behaviour on panic: delay <timeout>
2226 timeout > 0: seconds before rebooting
2227 timeout = 0: wait forever
2228 timeout < 0: reboot immediately
2231 parkbd.port= [HW] Parallel port number the keyboard adapter is
2232 connected to, default is 0.
2234 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
2235 0 for XT, 1 for AT (default is AT).
2238 parport= [HW,PPT] Specify parallel ports. 0 disables.
2239 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2240 Use 'auto' to force the driver to use any
2241 IRQ/DMA settings detected (the default is to
2242 ignore detected IRQ/DMA settings because of
2243 possible conflicts). You can specify the base
2244 address, IRQ, and DMA settings; IRQ and DMA
2245 should be numbers, or 'auto' (for using detected
2246 settings on that particular port), or 'nofifo'
2247 (to avoid using a FIFO even if it is detected).
2248 Parallel ports are assigned in the order they
2249 are specified on the command line, starting
2252 parport_init_mode= [HW,PPT]
2253 Configure VIA parallel port to operate in
2254 a specific mode. This is necessary on Pegasos
2255 computer where firmware has no options for setting
2256 up parallel port mode and sets it to spp.
2257 Currently this function knows 686a and 8231 chips.
2258 Format: [spp|ps2|epp|ecp|ecpepp]
2261 Halt all CPUs after the first oops has been printed for
2262 the specified number of seconds. This is to be used if
2263 your oopses keep scrolling off the screen.
2268 See header of drivers/block/paride/pcd.c.
2269 See also Documentation/blockdev/paride.txt.
2271 pci=option[,option...] [PCI] various PCI subsystem options:
2272 earlydump [X86] dump PCI config space before the kernel
2274 off [X86] don't probe for the PCI bus
2275 bios [X86-32] force use of PCI BIOS, don't access
2276 the hardware directly. Use this if your machine
2277 has a non-standard PCI host bridge.
2278 nobios [X86-32] disallow use of PCI BIOS, only direct
2279 hardware access methods are allowed. Use this
2280 if you experience crashes upon bootup and you
2281 suspect they are caused by the BIOS.
2282 conf1 [X86] Force use of PCI Configuration
2284 conf2 [X86] Force use of PCI Configuration
2286 noaer [PCIE] If the PCIEAER kernel config parameter is
2287 enabled, this kernel boot option can be used to
2288 disable the use of PCIE advanced error reporting.
2289 nodomains [PCI] Disable support for multiple PCI
2290 root domains (aka PCI segments, in ACPI-speak).
2291 nommconf [X86] Disable use of MMCONFIG for PCI
2293 check_enable_amd_mmconf [X86] check for and enable
2294 properly configured MMIO access to PCI
2295 config space on AMD family 10h CPU
2296 nomsi [MSI] If the PCI_MSI kernel config parameter is
2297 enabled, this kernel boot option can be used to
2298 disable the use of MSI interrupts system-wide.
2299 noioapicquirk [APIC] Disable all boot interrupt quirks.
2300 Safety option to keep boot IRQs enabled. This
2301 should never be necessary.
2302 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2303 primary IO-APIC for bridges that cannot disable
2304 boot IRQs. This fixes a source of spurious IRQs
2305 when the system masks IRQs.
2306 noioapicreroute [APIC] Disable workaround that uses the
2307 boot IRQ equivalent of an IRQ that connects to
2308 a chipset where boot IRQs cannot be disabled.
2309 The opposite of ioapicreroute.
2310 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2311 routing table. These calls are known to be buggy
2312 on several machines and they hang the machine
2313 when used, but on other computers it's the only
2314 way to get the interrupt routing table. Try
2315 this option if the kernel is unable to allocate
2316 IRQs or discover secondary PCI buses on your
2318 rom [X86] Assign address space to expansion ROMs.
2319 Use with caution as certain devices share
2320 address decoders between ROMs and other
2322 norom [X86] Do not assign address space to
2323 expansion ROMs that do not already have
2324 BIOS assigned address ranges.
2325 nobar [X86] Do not assign address space to the
2326 BARs that weren't assigned by the BIOS.
2327 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2328 assigned automatically to PCI devices. You can
2329 make the kernel exclude IRQs of your ISA cards
2331 pirqaddr=0xAAAAA [X86] Specify the physical address
2332 of the PIRQ table (normally generated
2333 by the BIOS) if it is outside the
2334 F0000h-100000h range.
2335 lastbus=N [X86] Scan all buses thru bus #N. Can be
2336 useful if the kernel is unable to find your
2337 secondary buses and you want to tell it
2338 explicitly which ones they are.
2339 assign-busses [X86] Always assign all PCI bus
2340 numbers ourselves, overriding
2341 whatever the firmware may have done.
2342 usepirqmask [X86] Honor the possible IRQ mask stored
2343 in the BIOS $PIR table. This is needed on
2344 some systems with broken BIOSes, notably
2345 some HP Pavilion N5400 and Omnibook XE3
2346 notebooks. This will have no effect if ACPI
2347 IRQ routing is enabled.
2348 noacpi [X86] Do not use ACPI for IRQ routing
2349 or for PCI scanning.
2350 use_crs [X86] Use PCI host bridge window information
2351 from ACPI. On BIOSes from 2008 or later, this
2352 is enabled by default. If you need to use this,
2353 please report a bug.
2354 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2355 If you need to use this, please report a bug.
2356 routeirq Do IRQ routing for all PCI devices.
2357 This is normally done in pci_enable_device(),
2358 so this option is a temporary workaround
2359 for broken drivers that don't call it.
2360 skip_isa_align [X86] do not align io start addr, so can
2361 handle more pci cards
2362 firmware [ARM] Do not re-enumerate the bus but instead
2363 just use the configuration from the
2364 bootloader. This is currently used on
2365 IXP2000 systems where the bus has to be
2366 configured a certain way for adjunct CPUs.
2367 noearly [X86] Don't do any early type 1 scanning.
2368 This might help on some broken boards which
2369 machine check when some devices' config space
2370 is read. But various workarounds are disabled
2371 and some IOMMU drivers will not work.
2372 bfsort Sort PCI devices into breadth-first order.
2373 This sorting is done to get a device
2374 order compatible with older (<= 2.4) kernels.
2375 nobfsort Don't sort PCI devices into breadth-first order.
2376 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
2377 tuning and use the BIOS-configured MPS defaults.
2378 pcie_bus_safe Set every device's MPS to the largest value
2379 supported by all devices below the root complex.
2380 pcie_bus_perf Set device MPS to the largest allowable MPS
2381 based on its parent bus. Also set MRRS (Max
2382 Read Request Size) to the largest supported
2383 value (no larger than the MPS that the device
2384 or bus can support) for best performance.
2385 pcie_bus_peer2peer Set every device's MPS to 128B, which
2386 every device is guaranteed to support. This
2387 configuration allows peer-to-peer DMA between
2388 any pair of devices, possibly at the cost of
2389 reduced performance. This also guarantees
2390 that hot-added devices will work.
2391 cbiosize=nn[KMG] The fixed amount of bus space which is
2392 reserved for the CardBus bridge's IO window.
2393 The default value is 256 bytes.
2394 cbmemsize=nn[KMG] The fixed amount of bus space which is
2395 reserved for the CardBus bridge's memory
2396 window. The default value is 64 megabytes.
2399 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2400 Specifies alignment and device to reassign
2401 aligned memory resources.
2402 If <order of align> is not specified,
2403 PAGE_SIZE is used as alignment.
2404 PCI-PCI bridge can be specified, if resource
2405 windows need to be expanded.
2406 ecrc= Enable/disable PCIe ECRC (transaction layer
2407 end-to-end CRC checking).
2408 bios: Use BIOS/firmware settings. This is the
2412 hpiosize=nn[KMG] The fixed amount of bus space which is
2413 reserved for hotplug bridge's IO window.
2414 Default size is 256 bytes.
2415 hpmemsize=nn[KMG] The fixed amount of bus space which is
2416 reserved for hotplug bridge's memory window.
2417 Default size is 2 megabytes.
2418 realloc= Enable/disable reallocating PCI bridge resources
2419 if allocations done by BIOS are too small to
2420 accommodate resources required by all child
2422 off: Turn realloc off
2424 realloc same as realloc=on
2425 noari do not use PCIe ARI.
2426 pcie_scan_all Scan all possible PCIe devices. Otherwise we
2427 only look for one device below a PCIe downstream
2430 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2433 force Enable ASPM even on devices that claim not to support it.
2434 WARNING: Forcing ASPM on may cause system lockups.
2436 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2437 nomsi Do not use MSI for PCI Express Native Hotplug (this
2438 makes all PCIe ports use INTx for hotplug services).
2440 pcie_ports= [PCIE] PCIe ports handling:
2441 auto Ask the BIOS whether or not to use native PCIe services
2442 associated with PCIe ports (PME, hot-plug, AER). Use
2443 them only if that is allowed by the BIOS.
2444 native Use native PCIe services associated with PCIe ports
2446 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2449 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2450 nomsi Do not use MSI for native PCIe PME signaling (this makes
2451 all PCIe root ports use INTx for all services).
2453 pcmv= [HW,PCMCIA] BadgePAD 4
2456 See Documentation/blockdev/paride.txt.
2458 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2461 See arch/parisc/kernel/pdc_chassis.c
2463 percpu_alloc= Select which percpu first chunk allocator to use.
2464 Currently supported values are "embed" and "page".
2465 Archs may support subset or none of the selections.
2466 See comments in mm/percpu.c for details on each
2467 allocator. This parameter is primarily for debugging
2468 and performance comparison.
2471 See Documentation/blockdev/paride.txt.
2474 See Documentation/blockdev/paride.txt.
2476 pirq= [SMP,APIC] Manual mp-table setup
2477 See Documentation/x86/i386/IO-APIC.txt.
2479 plip= [PPT,NET] Parallel port network link
2480 Format: { parport<nr> | timid | 0 }
2481 See also Documentation/parport.txt.
2483 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2484 Override pmtimer IOPort with a hex value.
2488 Enable PNP debug messages (depends on the
2489 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2490 via /sys/module/pnp/parameters/debug. We always show
2491 current resource usage; turning this on also shows
2492 possible settings and some assignment information.
2498 { on | off | curr | res | no-curr | no-res }
2501 [ISAPNP] Exclude IRQs for the autoconfiguration
2504 [ISAPNP] Exclude DMAs for the autoconfiguration
2506 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2507 Ranges are in pairs (I/O port base and size).
2510 [ISAPNP] Exclude memory regions for the
2512 Ranges are in pairs (memory base and size).
2514 ports= [IP_VS_FTP] IPVS ftp helper module
2516 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2518 Format: <port>,<port>....
2520 print-fatal-signals=
2521 [KNL] debug: print fatal signals
2523 If enabled, warn about various signal handling
2524 related application anomalies: too many signals,
2525 too many POSIX.1 timers, fatal signals causing a
2528 If you hit the warning due to signal overflow,
2529 you might want to try "ulimit -i unlimited".
2533 printk.always_kmsg_dump=
2534 Trigger kmsg_dump for cases other than kernel oops or
2536 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2539 printk.time= Show timing data prefixed to each printk message line
2540 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2542 processor.max_cstate= [HW,ACPI]
2543 Limit processor to maximum C-state
2544 max_cstate=9 overrides any DMI blacklist limit.
2546 processor.nocst [HW,ACPI]
2547 Ignore the _CST method to determine C-states,
2548 instead using the legacy FADT method
2550 profile= [KNL] Enable kernel profiling via /proc/profile
2551 Format: [schedule,]<number>
2552 Param: "schedule" - profile schedule points.
2553 Param: <number> - step/bucket size as a power of 2 for
2554 statistical time based profiling.
2555 Param: "sleep" - profile D-state sleeping (millisecs).
2556 Requires CONFIG_SCHEDSTATS
2557 Param: "kvm" - profile VM exits.
2559 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2561 See Documentation/blockdev/ramdisk.txt.
2563 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2564 probe for; one of (bare|imps|exps|lifebook|any).
2565 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2567 psmouse.resetafter= [HW,MOUSE]
2568 Try to reset the device after so many bad packets
2571 [HW,MOUSE] Set desired mouse resolution, in dpi.
2572 psmouse.smartscroll=
2573 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2574 0 = disabled, 1 = enabled (default).
2576 pstore.backend= Specify the name of the pstore backend to use
2579 See Documentation/blockdev/paride.txt.
2582 [KNL] Number of legacy pty's. Overwrites compiled-in
2585 quiet [KNL] Disable most log messages
2590 See Documentation/md.txt.
2592 ramdisk_blocksize= [RAM]
2593 See Documentation/blockdev/ramdisk.txt.
2595 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2596 See Documentation/blockdev/ramdisk.txt.
2598 rcu_nocbs= [KNL,BOOT]
2599 In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2600 the specified list of CPUs to be no-callback CPUs.
2601 Invocation of these CPUs' RCU callbacks will
2602 be offloaded to "rcuox/N" kthreads created for
2603 that purpose, where "x" is "b" for RCU-bh, "p"
2604 for RCU-preempt, and "s" for RCU-sched, and "N"
2605 is the CPU number. This reduces OS jitter on the
2606 offloaded CPUs, which can be useful for HPC and
2608 real-time workloads. It can also improve energy
2609 efficiency for asymmetric multiprocessors.
2611 rcu_nocb_poll [KNL,BOOT]
2612 Rather than requiring that offloaded CPUs
2613 (specified by rcu_nocbs= above) explicitly
2614 awaken the corresponding "rcuoN" kthreads,
2615 make these kthreads poll for callbacks.
2616 This improves the real-time response for the
2617 offloaded CPUs by relieving them of the need to
2618 wake up the corresponding kthread, but degrades
2619 energy efficiency by requiring that the kthreads
2620 periodically wake up to do the polling.
2622 rcutree.blimit= [KNL,BOOT]
2623 Set maximum number of finished RCU callbacks to process
2626 rcutree.fanout_leaf= [KNL,BOOT]
2627 Increase the number of CPUs assigned to each
2628 leaf rcu_node structure. Useful for very large
2631 rcutree.jiffies_till_first_fqs= [KNL,BOOT]
2632 Set delay from grace-period initialization to
2633 first attempt to force quiescent states.
2634 Units are jiffies, minimum value is zero,
2635 and maximum value is HZ.
2637 rcutree.jiffies_till_next_fqs= [KNL,BOOT]
2638 Set delay between subsequent attempts to force
2639 quiescent states. Units are jiffies, minimum
2640 value is one, and maximum value is HZ.
2642 rcutree.qhimark= [KNL,BOOT]
2643 Set threshold of queued
2644 RCU callbacks over which batch limiting is disabled.
2646 rcutree.qlowmark= [KNL,BOOT]
2647 Set threshold of queued RCU callbacks below which
2648 batch limiting is re-enabled.
2650 rcutree.rcu_cpu_stall_suppress= [KNL,BOOT]
2651 Suppress RCU CPU stall warning messages.
2653 rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
2654 Set timeout for RCU CPU stall warning messages.
2656 rcutree.rcu_idle_gp_delay= [KNL,BOOT]
2657 Set wakeup interval for idle CPUs that have
2658 RCU callbacks (RCU_FAST_NO_HZ=y).
2660 rcutree.rcu_idle_lazy_gp_delay= [KNL,BOOT]
2661 Set wakeup interval for idle CPUs that have
2662 only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
2663 Lazy RCU callbacks are those which RCU can
2664 prove do nothing more than free memory.
2666 rcutorture.fqs_duration= [KNL,BOOT]
2667 Set duration of force_quiescent_state bursts.
2669 rcutorture.fqs_holdoff= [KNL,BOOT]
2670 Set holdoff time within force_quiescent_state bursts.
2672 rcutorture.fqs_stutter= [KNL,BOOT]
2673 Set wait time between force_quiescent_state bursts.
2675 rcutorture.irqreader= [KNL,BOOT]
2676 Test RCU readers from irq handlers.
2678 rcutorture.n_barrier_cbs= [KNL,BOOT]
2679 Set callbacks/threads for rcu_barrier() testing.
2681 rcutorture.nfakewriters= [KNL,BOOT]
2682 Set number of concurrent RCU writers. These just
2683 stress RCU, they don't participate in the actual
2684 test, hence the "fake".
2686 rcutorture.nreaders= [KNL,BOOT]
2687 Set number of RCU readers.
2689 rcutorture.onoff_holdoff= [KNL,BOOT]
2690 Set time (s) after boot for CPU-hotplug testing.
2692 rcutorture.onoff_interval= [KNL,BOOT]
2693 Set time (s) between CPU-hotplug operations, or
2694 zero to disable CPU-hotplug testing.
2696 rcutorture.shuffle_interval= [KNL,BOOT]
2697 Set task-shuffle interval (s). Shuffling tasks
2698 allows some CPUs to go into dyntick-idle mode
2699 during the rcutorture test.
2701 rcutorture.shutdown_secs= [KNL,BOOT]
2702 Set time (s) after boot system shutdown. This
2703 is useful for hands-off automated testing.
2705 rcutorture.stall_cpu= [KNL,BOOT]
2706 Duration of CPU stall (s) to test RCU CPU stall
2707 warnings, zero to disable.
2709 rcutorture.stall_cpu_holdoff= [KNL,BOOT]
2710 Time to wait (s) after boot before inducing stall.
2712 rcutorture.stat_interval= [KNL,BOOT]
2713 Time (s) between statistics printk()s.
2715 rcutorture.stutter= [KNL,BOOT]
2716 Time (s) to stutter testing, for example, specifying
2717 five seconds causes the test to run for five seconds,
2718 wait for five seconds, and so on. This tests RCU's
2719 ability to transition abruptly to and from idle.
2721 rcutorture.test_boost= [KNL,BOOT]
2722 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
2723 "Maybe" means test if the RCU implementation
2724 under test support RCU priority boosting.
2726 rcutorture.test_boost_duration= [KNL,BOOT]
2727 Duration (s) of each individual boost test.
2729 rcutorture.test_boost_interval= [KNL,BOOT]
2730 Interval (s) between each boost test.
2732 rcutorture.test_no_idle_hz= [KNL,BOOT]
2733 Test RCU's dyntick-idle handling. See also the
2734 rcutorture.shuffle_interval parameter.
2736 rcutorture.torture_type= [KNL,BOOT]
2737 Specify the RCU implementation to test.
2739 rcutorture.verbose= [KNL,BOOT]
2740 Enable additional printk() statements.
2744 Run specified binary instead of /init from the ramdisk,
2745 used for early userspace startup. See initrd.
2748 Format (x86 or x86_64):
2749 [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
2751 [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
2753 Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
2754 reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
2755 reboot_force is either force or not specified,
2756 reboot_cpu is s[mp]#### with #### being the processor
2757 to be used for rebooting.
2760 [KNL, SMP] Set scheduler's default relax_domain_level.
2761 See Documentation/cgroups/cpusets.txt.
2763 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2765 reservetop= [X86-32]
2767 Reserves a hole at the top of the kernel virtual
2772 Set the amount of memory to reserve for BIOS at
2773 the bottom of the address space.
2775 reset_devices [KNL] Force drivers to reset the underlying device
2776 during initialization.
2779 Specify the partition device for software suspend
2781 {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
2783 resume_offset= [SWSUSP]
2784 Specify the offset from the beginning of the partition
2785 given by "resume=" at which the swap header is located,
2786 in <PAGE_SIZE> units (needed only for swap files).
2787 See Documentation/power/swsusp-and-swap-files.txt
2789 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2790 read the resume files
2792 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2793 Useful for devices that are detected asynchronously
2794 (e.g. USB and MMC devices).
2796 hibernate= [HIBERNATION]
2797 noresume Don't check if there's a hibernation image
2798 present during boot.
2799 nocompress Don't compress/decompress hibernation images.
2801 retain_initrd [RAM] Keep initrd memory after extraction
2803 rhash_entries= [KNL,NET]
2804 Set number of hash buckets for route cache
2806 riscom8= [HW,SERIAL]
2807 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2809 ro [KNL] Mount root device read-only on boot
2811 root= [KNL] Root filesystem
2812 See name_to_dev_t comment in init/do_mounts.c.
2814 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2815 mount the root filesystem
2817 rootflags= [KNL] Set root filesystem mount option string
2819 rootfstype= [KNL] Set root filesystem type
2821 rootwait [KNL] Wait (indefinitely) for root device to show up.
2822 Useful for devices that are detected asynchronously
2823 (e.g. USB and MMC devices).
2825 rproc_mem=nn[KMG][@address]
2826 [KNL,ARM,CMA] Remoteproc physical memory block.
2827 Memory area to be used by remote processor image,
2830 rw [KNL] Mount root device read-write on boot
2832 S [KNL] Run init in single mode
2835 See drivers/net/irda/sa1100_ir.c.
2837 sbni= [NET] Granch SBNI12 leased line adapter
2839 sched_debug [KNL] Enables verbose scheduler debug messages.
2841 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
2842 xtime_lock contention on larger systems, and/or RCU lock
2843 contention on all systems with CONFIG_MAXSMP set.
2844 Format: { "0" | "1" }
2845 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
2847 Note: increases power consumption, thus should only be
2848 enabled if running jitter sensitive (HPC/RT) workloads.
2850 security= [SECURITY] Choose a security module to enable at boot.
2851 If this boot parameter is not specified, only the first
2852 security module asking for security registration will be
2853 loaded. An invalid security module name will be treated
2854 as if no module has been chosen.
2856 selinux= [SELINUX] Disable or enable SELinux at boot time.
2857 Format: { "0" | "1" }
2858 See security/selinux/Kconfig help text.
2861 Default value is set via kernel config option.
2862 If enabled at boot time, /selinux/disable can be used
2863 later to disable prior to initial policy load.
2865 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2866 Format: { "0" | "1" }
2867 See security/apparmor/Kconfig help text
2870 Default value is set via kernel config option.
2872 serialnumber [BUGS=X86-32]
2875 Maximal number of shapers.
2877 show_msr= [x86] show boot-time MSR settings
2878 Format: { <integer> }
2879 Show boot-time (BIOS-initialized) MSR settings.
2880 The parameter means the number of CPUs to show,
2881 for example 1 means boot CPU only.
2888 slab_max_order= [MM, SLAB]
2889 Determines the maximum allowed order for slabs.
2890 A high setting may cause OOMs due to memory
2891 fragmentation. Defaults to 1 for systems with
2892 more than 32MB of RAM, 0 otherwise.
2894 slub_debug[=options[,slabs]] [MM, SLUB]
2895 Enabling slub_debug allows one to determine the
2896 culprit if slab objects become corrupted. Enabling
2897 slub_debug can create guard zones around objects and
2898 may poison objects when not in use. Also tracks the
2899 last alloc / free. For more information see
2900 Documentation/vm/slub.txt.
2902 slub_max_order= [MM, SLUB]
2903 Determines the maximum allowed order for slabs.
2904 A high setting may cause OOMs due to memory
2905 fragmentation. For more information see
2906 Documentation/vm/slub.txt.
2908 slub_min_objects= [MM, SLUB]
2909 The minimum number of objects per slab. SLUB will
2910 increase the slab order up to slub_max_order to
2911 generate a sufficiently large slab able to contain
2912 the number of objects indicated. The higher the number
2913 of objects the smaller the overhead of tracking slabs
2914 and the less frequently locks need to be acquired.
2915 For more information see Documentation/vm/slub.txt.
2917 slub_min_order= [MM, SLUB]
2918 Determines the minimum page order for slabs. Must be
2919 lower than slub_max_order.
2920 For more information see Documentation/vm/slub.txt.
2922 slub_nomerge [MM, SLUB]
2923 Disable merging of slabs with similar size. May be
2924 necessary if there is some reason to distinguish
2925 allocs to different slabs. Debug options disable
2926 merging on their own.
2927 For more information see Documentation/vm/slub.txt.
2930 Format: <io1>[,<io2>[,...,<io8>]]
2932 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2933 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2934 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2935 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2936 smsc-ircc2.ircc_irq= [HW] IRQ line
2937 smsc-ircc2.ircc_dma= [HW] DMA channel
2938 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2939 0: Toshiba Satellite 1800 (GP data pin select)
2940 1: Fast pin select (default)
2944 [KNL] Should the soft-lockup detector generate panics.
2947 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2948 See Documentation/laptops/sonypi.txt
2950 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2951 See Documentation/serial/specialix.txt.
2953 spia_io_base= [HW,MTD]
2959 Enabled the stack tracer on boot up.
2961 stacktrace_filter=[function-list]
2962 [FTRACE] Limit the functions that the stack tracer
2963 will trace at boot up. function-list is a comma separated
2964 list of functions. This list can be changed at run
2965 time by the stack_trace_filter file in the debugfs
2966 tracing directory. Note, this enables stack tracing
2967 and the stacktrace above is not needed.
2971 Set the STI (builtin display/keyboard on the HP-PARISC
2972 machines) console (graphic card) which should be used
2973 as the initial boot-console.
2974 See also comment in drivers/video/console/sticore.c.
2977 See comment in drivers/video/console/sticore.c.
2980 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2982 sunrpc.min_resvport=
2983 sunrpc.max_resvport=
2985 SunRPC servers often require that client requests
2986 originate from a privileged port (i.e. a port in the
2987 range 0 < portnr < 1024).
2988 An administrator who wishes to reserve some of these
2989 ports for other uses may adjust the range that the
2990 kernel's sunrpc client considers to be privileged
2991 using these two parameters to set the minimum and
2992 maximum port values.
2996 Control how the NFS server code allocates CPUs to
2997 service thread pools. Depending on how many NICs
2998 you have and where their interrupts are bound, this
2999 option will affect which CPUs will do NFS serving.
3000 Note: this parameter cannot be changed while the
3001 NFS server is running.
3003 auto the server chooses an appropriate mode
3004 automatically using heuristics
3005 global a single global pool contains all CPUs
3006 percpu one pool for each CPU
3007 pernode one pool for each NUMA node (equivalent
3008 to global on non-NUMA machines)
3010 sunrpc.tcp_slot_table_entries=
3011 sunrpc.udp_slot_table_entries=
3013 Sets the upper limit on the number of simultaneous
3014 RPC calls that can be sent from the client to a
3015 server. Increasing these values may allow you to
3016 improve throughput, but will also increase the
3017 amount of memory reserved for use by the client.
3020 [KNL] Enable accounting of swap in memory resource
3021 controller if no parameter or 1 is given or disable
3022 it if 0 is given (See Documentation/cgroups/memory.txt)
3024 swiotlb= [IA-64] Number of I/O TLB slabs
3028 sysfs.deprecated=0|1 [KNL]
3029 Enable/disable old style sysfs layout for old udev
3030 on older distributions. When this option is enabled
3031 very new udev will not work anymore. When this option
3032 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
3033 in older udev will not work anymore.
3034 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
3035 the kernel configuration.
3037 sysrq_always_enabled
3039 Ignore sysrq setting - this boot parameter will
3040 neutralize any effect of /proc/sys/kernel/sysrq.
3041 Useful for debugging.
3045 test_suspend= [SUSPEND]
3046 Specify "mem" (for Suspend-to-RAM) or "standby" (for
3047 standby suspend) as the system sleep state to briefly
3048 enter during system startup. The system is woken from
3049 this state using a wakeup-capable RTC alarm.
3051 thash_entries= [KNL,NET]
3052 Set number of hash buckets for TCP connection
3054 thermal.act= [HW,ACPI]
3055 -1: disable all active trip points in all thermal zones
3056 <degrees C>: override all lowest active trip points
3058 thermal.crt= [HW,ACPI]
3059 -1: disable all critical trip points in all thermal zones
3060 <degrees C>: override all critical trip points
3062 thermal.nocrt= [HW,ACPI]
3063 Set to disable actions on ACPI thermal zone
3064 critical and hot trip points.
3066 thermal.off= [HW,ACPI]
3067 1: disable ACPI thermal control
3069 thermal.psv= [HW,ACPI]
3070 -1: disable all passive trip points
3071 <degrees C>: override all passive trip points to this
3074 thermal.tzp= [HW,ACPI]
3075 Specify global default ACPI thermal zone polling rate
3076 <deci-seconds>: poll all this frequency
3077 0: no polling (default)
3080 Force threading of all interrupt handlers except those
3081 marked explicitly IRQF_NO_THREAD.
3084 Enable the Transcendent memory driver if built-in.
3086 tmem.cleancache=0|1 [KNL, XEN]
3087 Default is on (1). Disable the usage of the cleancache
3088 API to send anonymous pages to the hypervisor.
3090 tmem.frontswap=0|1 [KNL, XEN]
3091 Default is on (1). Disable the usage of the frontswap
3092 API to send swap pages to the hypervisor. If disabled
3093 the selfballooning and selfshrinking are force disabled.
3095 tmem.selfballooning=0|1 [KNL, XEN]
3096 Default is on (1). Disable the driving of swap pages
3099 tmem.selfshrinking=0|1 [KNL, XEN]
3100 Default is on (1). Partial swapoff that immediately
3101 transfers pages from Xen hypervisor back to the
3102 kernel based on different criteria.
3106 Specify if the kernel should make use of the cpu
3107 topology information if the hardware supports this.
3108 The scheduler will make use of this information and
3109 e.g. base its process migration decisions on it.
3114 tpm_suspend_pcr=[HW,TPM]
3115 Format: integer pcr id
3116 Specify that at suspend time, the tpm driver
3117 should extend the specified pcr with zeros,
3118 as a workaround for some chips which fail to
3119 flush the last written pcr on TPM_SaveState.
3120 This will guarantee that all the other pcrs
3123 trace_buf_size=nn[KMG]
3124 [FTRACE] will set tracing buffer size.
3126 trace_event=[event-list]
3127 [FTRACE] Set and start specified trace events in order
3128 to facilitate early boot debugging.
3129 See also Documentation/trace/events.txt
3131 trace_options=[option-list]
3132 [FTRACE] Enable or disable tracer options at boot.
3133 The option-list is a comma delimited list of options
3134 that can be enabled or disabled just as if you were
3135 to echo the option name into
3137 /sys/kernel/debug/tracing/trace_options
3139 For example, to enable stacktrace option (to dump the
3140 stack trace of each event), add to the command line:
3142 trace_options=stacktrace
3144 See also Documentation/trace/ftrace.txt "trace options"
3148 [FTRACE] enable this option to disable tracing when a
3149 warning is hit. This turns off "tracing_on". Tracing can
3150 be enabled again by echoing '1' into the "tracing_on"
3151 file located in /sys/kernel/debug/tracing/
3153 This option is useful, as it disables the trace before
3154 the WARNING dump is called, which prevents the trace to
3155 be filled with content caused by the warning output.
3157 This option can also be set at run time via the sysctl
3158 option: kernel/traceoff_on_warning
3160 transparent_hugepage=
3162 Format: [always|madvise|never]
3163 Can be used to control the default behavior of the system
3164 with respect to transparent hugepages.
3165 See Documentation/vm/transhuge.txt for more details.
3167 tsc= Disable clocksource stability checks for TSC.
3169 [x86] reliable: mark tsc clocksource as reliable, this
3170 disables clocksource verification at runtime, as well
3171 as the stability checks done at bootup. Used to enable
3172 high-resolution timer mode on older hardware, and in
3173 virtualized environment.
3174 [x86] noirqtime: Do not use TSC to do irq accounting.
3175 Used to run time disable IRQ_TIME_ACCOUNTING on any
3176 platforms where RDTSC is slow and this accounting
3179 turbografx.map[2|3]= [HW,JOY]
3180 TurboGraFX parallel port interface
3182 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
3183 See also Documentation/input/joystick-parport.txt
3185 udbg-immortal [PPC] When debugging early kernel crashes that
3186 happen after console_init() and before a proper
3187 console driver takes over, this boot options might
3188 help "seeing" what's going on.
3190 uhash_entries= [KNL,NET]
3191 Set number of hash buckets for UDP/UDP-Lite connections
3194 [USB] Ignore overcurrent events (default N).
3195 Some badly-designed motherboards generate lots of
3196 bogus events, for ports that aren't wired to
3197 anything. Set this parameter to avoid log spamming.
3198 Note that genuine overcurrent events won't be
3202 [X86] Cause panic on unknown NMI.
3204 usbcore.authorized_default=
3205 [USB] Default USB device authorization:
3206 (default -1 = authorized except for wireless USB,
3207 0 = not authorized, 1 = authorized)
3209 usbcore.autosuspend=
3210 [USB] The autosuspend time delay (in seconds) used
3211 for newly-detected USB devices (default 2). This
3212 is the time required before an idle device will be
3213 autosuspended. Devices for which the delay is set
3214 to a negative value won't be autosuspended at all.
3216 usbcore.usbfs_snoop=
3217 [USB] Set to log all usbfs traffic (default 0 = off).
3219 usbcore.blinkenlights=
3220 [USB] Set to cycle leds on hubs (default 0 = off).
3222 usbcore.old_scheme_first=
3223 [USB] Start with the old device initialization
3224 scheme (default 0 = off).
3226 usbcore.usbfs_memory_mb=
3227 [USB] Memory limit (in MB) for buffers allocated by
3228 usbfs (default = 16, 0 = max = 2047).
3230 usbcore.use_both_schemes=
3231 [USB] Try the other device initialization scheme
3232 if the first one fails (default 1 = enabled).
3234 usbcore.initial_descriptor_timeout=
3235 [USB] Specifies timeout for the initial 64-byte
3236 USB_REQ_GET_DESCRIPTOR request in milliseconds
3237 (default 5000 = 5.0 seconds).
3240 [USBHID] The interval which mice are to be polled at.
3242 usb-storage.delay_use=
3243 [UMS] The delay in seconds before a new device is
3244 scanned for Logical Units (default 5).
3247 [UMS] A list of quirks entries to supplement or
3248 override the built-in unusual_devs list. List
3249 entries are separated by commas. Each entry has
3250 the form VID:PID:Flags where VID and PID are Vendor
3251 and Product ID values (4-digit hex numbers) and
3252 Flags is a set of characters, each corresponding
3253 to a common usb-storage quirk flag as follows:
3254 a = SANE_SENSE (collect more than 18 bytes
3256 b = BAD_SENSE (don't collect more than 18
3257 bytes of sense data);
3258 c = FIX_CAPACITY (decrease the reported
3259 device capacity by one sector);
3260 d = NO_READ_DISC_INFO (don't use
3261 READ_DISC_INFO command);
3262 e = NO_READ_CAPACITY_16 (don't use
3263 READ_CAPACITY_16 command);
3264 h = CAPACITY_HEURISTICS (decrease the
3265 reported device capacity by one
3266 sector if the number is odd);
3267 i = IGNORE_DEVICE (don't bind to this
3269 l = NOT_LOCKABLE (don't try to lock and
3270 unlock ejectable media);
3271 m = MAX_SECTORS_64 (don't transfer more
3272 than 64 sectors = 32 KB at a time);
3273 n = INITIAL_READ10 (force a retry of the
3274 initial READ(10) command);
3275 o = CAPACITY_OK (accept the capacity
3276 reported by the device);
3277 p = WRITE_CACHE (the device cache is ON
3279 r = IGNORE_RESIDUE (the device reports
3280 bogus residue values);
3281 s = SINGLE_LUN (the device has only one
3283 w = NO_WP_DETECT (don't test whether the
3284 medium is write-protected).
3285 Example: quirks=0419:aaf5:rl,0421:0433:rc
3287 user_debug= [KNL,ARM]
3289 See arch/arm/Kconfig.debug help text.
3290 1 - undefined instruction events
3292 4 - invalid data aborts
3295 Example: user_debug=31
3298 [X86] Flags controlling user PTE allocations.
3300 nohigh = do not allocate PTE pages in
3301 HIGHMEM regardless of setting
3305 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
3306 vdso=1: enable VDSO (default)
3307 vdso=0: disable VDSO mapping
3310 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
3311 vdso32=1: enable 32-bit VDSO (default)
3312 vdso32=0: disable 32-bit VDSO mapping
3315 vector=percpu: enable percpu vector domain
3317 video= [FB] Frame buffer configuration
3318 See Documentation/fb/modedb.txt.
3320 video.brightness_switch_enabled= [0,1]
3321 If set to 1, on receiving an ACPI notify event
3322 generated by hotkey, video driver will adjust brightness
3323 level and then send out the event to user space through
3324 the allocated input device; If set to 0, video driver
3325 will only send out the event without touching backlight
3330 [VMMIO] Memory mapped virtio (platform) device.
3332 <size>@<baseaddr>:<irq>[:<id>]
3334 <size> := size (can use standard suffixes
3336 <baseaddr> := physical base address
3337 <irq> := interrupt number (as passed to
3339 <id> := (optional) platform device id
3341 virtio_mmio.device=1K@0x100b0000:48:7
3343 Can be used multiple times for multiple devices.
3345 vga= [BOOT,X86-32] Select a particular video mode
3346 See Documentation/x86/boot.txt and
3347 Documentation/svga.txt.
3348 Use vga=ask for menu.
3349 This is actually a boot loader parameter; the value is
3350 passed to the kernel using a special protocol.
3352 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
3353 size of <nn>. This can be used to increase the
3354 minimum size (128MB on x86). It can also be used to
3355 decrease the size and leave more room for directly
3358 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
3361 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
3364 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
3368 Controls the behavior of vsyscalls (i.e. calls to
3369 fixed addresses of 0xffffffffff600x00 from legacy
3370 code). Most statically-linked binaries and older
3371 versions of glibc use these calls. Because these
3372 functions are at fixed addresses, they make nice
3373 targets for exploits that can control RIP.
3375 emulate [default] Vsyscalls turn into traps and are
3376 emulated reasonably safely.
3378 native Vsyscalls are native syscall instructions.
3379 This is a little bit faster than trapping
3380 and makes a few dynamic recompilers work
3381 better than they would in emulation mode.
3382 It also makes exploits much easier to write.
3384 none Vsyscalls don't work at all. This makes
3385 them quite hard to use for exploits but
3386 might break your system.
3388 vt.color= [VT] Default text color.
3389 Format: 0xYX, X = foreground, Y = background.
3390 Default: 0x07 = light gray on black.
3392 vt.cur_default= [VT] Default cursor shape.
3393 Format: 0xCCBBAA, where AA, BB, and CC are the same as
3394 the parameters of the <Esc>[?A;B;Cc escape sequence;
3395 see VGA-softcursor.txt. Default: 2 = underline.
3397 vt.default_blu= [VT]
3398 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3399 Change the default blue palette of the console.
3400 This is a 16-member array composed of values
3403 vt.default_grn= [VT]
3404 Format: <green0>,<green1>,<green2>,...,<green15>
3405 Change the default green palette of the console.
3406 This is a 16-member array composed of values
3409 vt.default_red= [VT]
3410 Format: <red0>,<red1>,<red2>,...,<red15>
3411 Change the default red palette of the console.
3412 This is a 16-member array composed of values
3418 Set system-wide default UTF-8 mode for all tty's.
3419 Default is 1, i.e. UTF-8 mode is enabled for all
3420 newly opened terminals.
3422 vt.global_cursor_default=
3425 Set system-wide default for whether a cursor
3426 is shown on new VTs. Default is -1,
3427 i.e. cursors will be created by default unless
3428 overridden by individual drivers. 0 will hide
3429 cursors, 1 will display them.
3431 vt.italic= [VT] Default color for italic text; 0-15.
3434 vt.underline= [VT] Default color for underlined text; 0-15.
3437 watchdog timers [HW,WDT] For information on watchdog timers,
3438 see Documentation/watchdog/watchdog-parameters.txt
3439 or other driver-specific files in the
3440 Documentation/watchdog/ directory.
3442 workqueue.disable_numa
3443 By default, all work items queued to unbound
3444 workqueues are affine to the NUMA nodes they're
3445 issued on, which results in better behavior in
3446 general. If NUMA affinity needs to be disabled for
3447 whatever reason, this option can be used. Note
3448 that this also can be controlled per-workqueue for
3449 workqueues visible under /sys/bus/workqueue/.
3451 workqueue.power_efficient
3452 Per-cpu workqueues are generally preferred because
3453 they show better performance thanks to cache
3454 locality; unfortunately, per-cpu workqueues tend to
3455 be more power hungry than unbound workqueues.
3457 Enabling this makes the per-cpu workqueues which
3458 were observed to contribute significantly to power
3459 consumption unbound, leading to measurably lower
3460 power usage at the cost of small performance
3463 The default value of this parameter is determined by
3464 the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
3466 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
3467 default x2apic cluster mode on platforms
3470 x86_mrst_timer= [X86-32,APBT]
3471 Choose timer option for x86 Moorestown MID platform.
3472 Two valid options are apbt timer only and lapic timer
3473 plus one apbt timer for broadcast timer.
3474 x86_mrst_timer=apbt_only | lapic_and_apbt
3476 xen_emul_unplug= [HW,X86,XEN]
3477 Unplug Xen emulated devices
3478 Format: [unplug0,][unplug1]
3479 ide-disks -- unplug primary master IDE devices
3480 aux-ide-disks -- unplug non-primary-master IDE devices
3481 nics -- unplug network devices
3482 all -- unplug all emulated devices (NICs and IDE disks)
3483 unnecessary -- unplugging emulated devices is
3484 unnecessary even if the host did not respond to
3486 never -- do not unplug even if version check succeeds
3488 xirc2ps_cs= [NET,PCMCIA]
3490 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
3492 ______________________________________________________________________
3496 Add more DRM drivers.
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blob