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 blkdevparts= Manual partition parsing of block device(s) for
484 embedded devices based on command line input.
485 See Documentation/block/cmdline-partition.txt
487 boot_delay= Milliseconds to delay each printk during boot.
488 Values larger than 10 seconds (10000) are changed to
492 bootmem_debug [KNL] Enable bootmem allocator debug messages.
494 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
495 bttv.radio= Most important insmod options are available as
497 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
500 bulk_remove=off [PPC] This parameter disables the use of the pSeries
501 firmware feature for flushing multiple hpte entries
504 c101= [NET] Moxa C101 synchronous serial card
506 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
507 Sometimes CPU hardware bugs make them report the cache
508 size incorrectly. The kernel will attempt work arounds
509 to fix known problems, but for some CPUs it is not
510 possible to determine what the correct size should be.
511 This option provides an override for these situations.
513 ccw_timeout_log [S390]
514 See Documentation/s390/CommonIO for details.
516 cgroup_disable= [KNL] Disable a particular controller
517 Format: {name of the controller(s) to disable}
518 {Currently supported controllers - "memory"}
520 checkreqprot [SELINUX] Set initial checkreqprot flag value.
521 Format: { "0" | "1" }
522 See security/selinux/Kconfig help text.
523 0 -- check protection applied by kernel (includes
524 any implied execute protection).
525 1 -- check protection requested by application.
526 Default value is set via a kernel config option.
527 Value can be changed at runtime via
528 /selinux/checkreqprot.
531 See Documentation/s390/CommonIO for details.
534 Keep all clocks already enabled by bootloader on,
535 even if no driver has claimed them. This is useful
536 for debug and development, but should not be
537 needed on a platform with proper driver support.
538 For more information, see Documentation/clk.txt.
540 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
542 Forces specified clocksource (if available) to be used
543 when calculating gettimeofday(). If specified
544 clocksource is not available, it defaults to PIT.
545 Format: { pit | tsc | cyclone | pmtmr }
547 clocksource= Override the default clocksource
549 Override the default clocksource and use the clocksource
550 with the name specified.
551 Some clocksource names to choose from, depending on
553 [all] jiffies (this is the base, fallback clocksource)
555 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
556 pxa_timer,timer3,32k_counter,timer0_1
558 [X86-32] pit,hpet,tsc;
559 scx200_hrt on Geode; cyclone on IBM x440
567 clearcpuid=BITNUM [X86]
568 Disable CPUID feature X for the kernel. See
569 arch/x86/include/asm/cpufeature.h for the valid bit
570 numbers. Note the Linux specific bits are not necessarily
571 stable over kernel options, but the vendor specific
573 Also note that user programs calling CPUID directly
574 or using the feature without checking anything
575 will still see it. This just prevents it from
576 being used by the kernel or shown in /proc/cpuinfo.
577 Also note the kernel might malfunction if you disable
581 Sets the size of kernel global memory area for contiguous
582 memory allocations. For more information, see
583 include/linux/dma-contiguous.h
585 cmo_free_hint= [PPC] Format: { yes | no }
586 Specify whether pages are marked as being inactive
587 when they are freed. This is used in CMO environments
588 to determine OS memory pressure for page stealing by
592 coherent_pool=nn[KMG] [ARM,KNL]
593 Sets the size of memory pool for coherent, atomic dma
594 allocations, by default set to 256K.
596 code_bytes [X86] How many bytes of object code to print
601 com20020= [HW,NET] ARCnet - COM20020 chipset
603 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
605 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
609 ARCnet - COM90xx chipset (memory-mapped buffers)
610 Format: <io>[,<irq>[,<memstart>]]
612 condev= [HW,S390] console device
615 console= [KNL] Output console device and options.
617 tty<n> Use the virtual console device <n>.
621 Use the specified serial port. The options are of
622 the form "bbbbpnf", where "bbbb" is the baud rate,
623 "p" is parity ("n", "o", or "e"), "n" is number of
624 bits, and "f" is flow control ("r" for RTS or
625 omit it). Default is "9600n8".
627 See Documentation/serial-console.txt for more
629 Documentation/networking/netconsole.txt for an
632 uart[8250],io,<addr>[,options]
633 uart[8250],mmio,<addr>[,options]
634 Start an early, polled-mode console on the 8250/16550
635 UART at the specified I/O port or MMIO address,
636 switching to the matching ttyS device later. The
637 options are the same as for ttyS, above.
638 hvc<n> Use the hypervisor console device <n>. This is for
639 both Xen and PowerPC hypervisors.
641 If the device connected to the port is not a TTY but a braille
642 device, prepend "brl," before the device type, for instance
644 For now, only VisioBraille is supported.
646 consoleblank= [KNL] The console blank (screen saver) timeout in
647 seconds. Defaults to 10*60 = 10mins. A value of 0
648 disables the blank timer.
651 [KNL] Change the default value for
652 /proc/<pid>/coredump_filter.
653 See also Documentation/filesystems/proc.txt.
655 cpuidle.off=1 [CPU_IDLE]
656 disable the cpuidle sub-system
658 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
660 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
662 crashkernel=size[KMG][@offset[KMG]]
663 [KNL] Using kexec, Linux can switch to a 'crash kernel'
664 upon panic. This parameter reserves the physical
665 memory region [offset, offset + size] for that kernel
666 image. If '@offset' is omitted, then a suitable offset
667 is selected automatically. Check
668 Documentation/kdump/kdump.txt for further details.
670 crashkernel=range1:size1[,range2:size2,...][@offset]
671 [KNL] Same as above, but depends on the memory
672 in the running system. The syntax of range is
673 start-[end] where start and end are both
674 a memory unit (amount[KMG]). See also
675 Documentation/kdump/kdump.txt for an example.
677 crashkernel=size[KMG],high
678 [KNL, x86_64] range could be above 4G. Allow kernel
679 to allocate physical memory region from top, so could
680 be above 4G if system have more than 4G ram installed.
681 Otherwise memory region will be allocated below 4G, if
683 It will be ignored if crashkernel=X is specified.
684 crashkernel=size[KMG],low
685 [KNL, x86_64] range under 4G. When crashkernel=X,high
686 is passed, kernel could allocate physical memory region
687 above 4G, that cause second kernel crash on system
688 that require some amount of low memory, e.g. swiotlb
689 requires at least 64M+32K low memory. Kernel would
690 try to allocate 72M below 4G automatically.
691 This one let user to specify own low range under 4G
692 for second kernel instead.
693 0: to disable low allocation.
694 It will be ignored when crashkernel=X,high is not used
695 or memory reserved is below 4G.
700 cs89x0_media= [HW,NET]
701 Format: { rj45 | aui | bnc }
704 See header of drivers/s390/block/dasd_devmap.c.
706 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
707 (one device per port)
708 Format: <port#>,<type>
709 See also Documentation/input/joystick-parport.txt
711 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
712 time. See Documentation/dynamic-debug-howto.txt for
713 details. Deprecated, see dyndbg.
715 debug [KNL] Enable kernel debugging (events log level).
718 [KNL] verbose self-tests
720 Print debugging info while doing the locking API
722 We default to 0 (no extra messages), setting it to
723 1 will print _a lot_ more information - normally
724 only useful to kernel developers.
726 debug_objects [KNL] Enable object debugging
729 [KNL] Disable object debugging
731 debug_guardpage_minorder=
732 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
733 parameter allows control of the order of pages that will
734 be intentionally kept free (and hence protected) by the
735 buddy allocator. Bigger value increase the probability
736 of catching random memory corruption, but reduce the
737 amount of memory for normal system use. The maximum
738 possible value is MAX_ORDER/2. Setting this parameter
739 to 1 or 2 should be enough to identify most random
740 memory corruption problems caused by bugs in kernel or
741 driver code when a CPU writes to (or reads from) a
742 random memory location. Note that there exists a class
743 of memory corruptions problems caused by buggy H/W or
744 F/W or by drivers badly programing DMA (basically when
745 memory is written at bus level and the CPU MMU is
746 bypassed) which are not detectable by
747 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
748 tracking down these problems.
750 debugpat [X86] Enable PAT debugging
752 decnet.addr= [HW,NET]
753 Format: <area>[,<node>]
754 See also Documentation/networking/decnet.txt.
757 [same as hugepagesz=] The size of the default
758 HugeTLB page size. This is the size represented by
759 the legacy /proc/ hugepages APIs, used for SHM, and
760 default size when mounting hugetlbfs filesystems.
761 Defaults to the default architecture's huge page size
765 Set number of hash buckets for dentry cache.
768 IO parameters + enable/disable command.
770 digiepca= [HW,SERIAL]
771 See drivers/char/README.epca and
772 Documentation/serial/digiepca.txt.
775 See Documentation/networking/ipv6.txt.
777 disable_ddw [PPC/PSERIES]
778 Disable Dynamic DMA Window support. Use this if
779 to workaround buggy firmware.
782 See Documentation/networking/ipv6.txt.
784 disable_mtrr_cleanup [X86]
785 The kernel tries to adjust MTRR layout from continuous
786 to discrete, to make X server driver able to add WB
787 entry later. This parameter disables that.
789 disable_mtrr_trim [X86, Intel and AMD only]
790 By default the kernel will trim any uncacheable
791 memory out of your available memory pool based on
792 MTRR settings. This parameter disables that behavior,
793 possibly causing your machine to run very slowly.
795 disable_timer_pin_1 [X86]
796 Disable PIN 1 of APIC timer
797 Can be useful to work around chipset bugs.
799 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
800 this option disables the debugging code at boot.
802 dma_debug_entries=<number>
803 This option allows to tune the number of preallocated
804 entries for DMA-API debugging code. One entry is
805 required per DMA-API allocation. Use this if the
806 DMA-API debugging code disables itself because the
807 architectural default is too low.
809 dma_debug_driver=<driver_name>
810 With this option the DMA-API debugging driver
811 filter feature can be enabled at boot time. Just
812 pass the driver to filter for as the parameter.
813 The filter can be disabled or changed to another
814 driver later using sysfs.
816 drm_kms_helper.edid_firmware=[<connector>:]<file>
817 Broken monitors, graphic adapters and KVMs may
818 send no or incorrect EDID data sets. This parameter
819 allows to specify an EDID data set in the
820 /lib/firmware directory that is used instead.
821 Generic built-in EDID data sets are used, if one of
822 edid/1024x768.bin, edid/1280x1024.bin,
823 edid/1680x1050.bin, or edid/1920x1080.bin is given
824 and no file with the same name exists. Details and
825 instructions how to build your own EDID data are
826 available in Documentation/EDID/HOWTO.txt. An EDID
827 data set will only be used for a particular connector,
828 if its name and a colon are prepended to the EDID
833 dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
834 module.dyndbg[="val"]
835 Enable debug messages at boot time. See
836 Documentation/dynamic-debug-howto.txt for details.
838 earlycon= [KNL] Output early console device and options.
839 uart[8250],io,<addr>[,options]
840 uart[8250],mmio,<addr>[,options]
841 uart[8250],mmio32,<addr>[,options]
842 Start an early, polled-mode console on the 8250/16550
843 UART at the specified I/O port or MMIO address.
844 MMIO inter-register address stride is either 8-bit
845 (mmio) or 32-bit (mmio32).
846 The options are the same as for ttyS, above.
848 earlyprintk= [X86,SH,BLACKFIN,ARM]
852 earlyprintk=serial[,ttySn[,baudrate]]
853 earlyprintk=serial[,0x...[,baudrate]]
854 earlyprintk=ttySn[,baudrate]
855 earlyprintk=dbgp[debugController#]
857 earlyprintk is useful when the kernel crashes before
858 the normal console is initialized. It is not enabled by
859 default because it has some cosmetic problems.
861 Append ",keep" to not disable it when the real console
864 Only one of vga, efi, serial, or usb debug port can
867 Currently only ttyS0 and ttyS1 may be specified by
868 name. Other I/O ports may be explicitly specified
869 on some architectures (x86 and arm at least) by
870 replacing ttySn with an I/O port address, like this:
871 earlyprintk=serial,0x1008,115200
872 You can find the port for a given device in
873 /proc/tty/driver/serial:
874 2: uart:ST16650V2 port:00001008 irq:18 ...
876 Interaction with the standard serial driver is not
879 The VGA and EFI output is eventually overwritten by
882 The xen output can only be used by Xen PV guests.
884 ekgdboc= [X86,KGDB] Allow early kernel console debugging
887 This is designed to be used in conjunction with
888 the boot argument: earlyprintk=vga
891 Format: {"off" | "on" | "skip[mbr]"}
893 efi_no_storage_paranoia [EFI; X86]
894 Using this parameter you can use more than 50% of
895 your efi variable storage. Use this parameter only if
896 you are really sure that your UEFI does sane gc and
897 fulfills the spec otherwise your board may brick.
899 eisa_irq_edge= [PARISC,HW]
900 See header of drivers/parisc/eisa.c.
903 See comment before function elanfreq_setup() in
904 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
907 Format: {"cfq" | "deadline" | "noop"}
908 See Documentation/block/cfq-iosched.txt and
909 Documentation/block/deadline-iosched.txt for details.
911 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
912 Specifies physical address of start of kernel core
913 image elf header and optionally the size. Generally
914 kexec loader will pass this option to capture kernel.
915 See Documentation/kdump/kdump.txt for details.
917 enable_mtrr_cleanup [X86]
918 The kernel tries to adjust MTRR layout from continuous
919 to discrete, to make X server driver able to add WB
920 entry later. This parameter enables that.
922 enable_timer_pin_1 [X86]
923 Enable PIN 1 of APIC timer
924 Can be useful to work around chipset bugs
925 (in particular on some ATI chipsets).
926 The kernel tries to set a reasonable default.
928 enforcing [SELINUX] Set initial enforcing status.
930 See security/selinux/Kconfig help text.
931 0 -- permissive (log only, no denials).
932 1 -- enforcing (deny and log).
934 Value can be changed at runtime via /selinux/enforce.
937 Disable Error Record Serialization Table (ERST)
940 ether= [HW,NET] Ethernet cards parameters
941 This option is obsoleted by the "netdev=" option, which
942 has equivalent usage. See its documentation for details.
946 Permit 'security.evm' to be updated regardless of
947 current integrity status.
951 fail_make_request=[KNL]
952 General fault injection mechanism.
953 Format: <interval>,<probability>,<space>,<times>
954 See also Documentation/fault-injection/.
957 See Documentation/blockdev/floppy.txt.
959 force_pal_cache_flush
960 [IA-64] Avoid check_sal_cache_flush which may hang on
961 buggy SAL_CACHE_FLUSH implementations. Using this
962 parameter will force ia64_sal_cache_flush to call
963 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
966 [FTRACE] will set and start the specified tracer
967 as early as possible in order to facilitate early
970 ftrace_dump_on_oops[=orig_cpu]
971 [FTRACE] will dump the trace buffers on oops.
972 If no parameter is passed, ftrace will dump
973 buffers of all CPUs, but if you pass orig_cpu, it will
974 dump only the buffer of the CPU that triggered the
977 ftrace_filter=[function-list]
978 [FTRACE] Limit the functions traced by the function
979 tracer at boot up. function-list is a comma separated
980 list of functions. This list can be changed at run
981 time by the set_ftrace_filter file in the debugfs
984 ftrace_notrace=[function-list]
985 [FTRACE] Do not trace the functions specified in
986 function-list. This list can be changed at run time
987 by the set_ftrace_notrace file in the debugfs
990 ftrace_graph_filter=[function-list]
991 [FTRACE] Limit the top level callers functions traced
992 by the function graph tracer at boot up.
993 function-list is a comma separated list of functions
994 that can be changed at run time by the
995 set_graph_function file in the debugfs tracing directory.
998 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
999 support via parallel port (up to 5 devices per port)
1000 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1001 See also Documentation/input/joystick-parport.txt
1005 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
1009 gcov_persist= [GCOV] When non-zero (default), profiling data for
1010 kernel modules is saved and remains accessible via
1011 debugfs, even when the module is unloaded/reloaded.
1012 When zero, profiling data is discarded and associated
1013 debugfs files are removed at module unload time.
1015 gpt [EFI] Forces disk with valid GPT signature but
1016 invalid Protective MBR to be treated as GPT.
1018 grcan.enable0= [HW] Configuration of physical interface 0. Determines
1019 the "Enable 0" bit of the configuration register.
1022 grcan.enable1= [HW] Configuration of physical interface 1. Determines
1023 the "Enable 0" bit of the configuration register.
1026 grcan.select= [HW] Select which physical interface to use.
1029 grcan.txsize= [HW] Sets the size of the tx buffer.
1030 Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1032 grcan.rxsize= [HW] Sets the size of the rx buffer.
1033 Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1036 hashdist= [KNL,NUMA] Large hashes allocated during boot
1037 are distributed across NUMA nodes. Defaults on
1038 for 64-bit NUMA, off otherwise.
1039 Format: 0 | 1 (for off | on)
1041 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1043 hd= [EIDE] (E)IDE hard drive subsystem geometry
1044 Format: <cyl>,<head>,<sect>
1047 Disable Hardware Error Source Table (HEST) support;
1048 corresponding firmware-first mode error processing
1049 logic will be disabled.
1051 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
1052 size of <nn>. This works even on boxes that have no
1053 highmem otherwise. This also works to reduce highmem
1054 size on bigger boxes.
1056 highres= [KNL] Enable/disable high resolution timer mode.
1057 Valid parameters: "on", "off"
1061 See Documentation/isdn/README.HiSax.
1065 hpet= [X86-32,HPET] option to control HPET usage
1066 Format: { enable (default) | disable | force |
1068 disable: disable HPET and use PIT instead
1069 force: allow force enabled of undocumented chips (ICH4,
1071 verbose: show contents of HPET registers during setup
1073 hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET
1074 registers. Default set by CONFIG_HPET_MMAP_DEFAULT.
1076 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1077 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
1078 On x86-64 and powerpc, this option can be specified
1079 multiple times interleaved with hugepages= to reserve
1080 huge pages of different sizes. Valid pages sizes on
1081 x86-64 are 2M (when the CPU supports "pse") and 1G
1082 (when the CPU supports the "pdpe1gb" cpuinfo flag)
1083 Note that 1GB pages can only be allocated at boot time
1084 using hugepages= and not freed afterwards.
1086 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
1087 terminal devices. Valid values: 0..8
1088 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1089 If specified, z/VM IUCV HVC accepts connections
1090 from listed z/VM user IDs only.
1092 hwthread_map= [METAG] Comma-separated list of Linux cpu id to
1093 hardware thread id mappings.
1094 Format: <cpu>:<hwthread>
1097 Do not unregister boot console at start. This is only
1098 useful for debugging when something happens in the window
1099 between unregistering the boot console and initializing
1102 i2c_bus= [HW] Override the default board specific I2C bus speed
1103 or register an additional I2C bus that is not
1104 registered from board initialization code.
1108 i8042.debug [HW] Toggle i8042 debug mode
1109 i8042.direct [HW] Put keyboard port into non-translated mode
1110 i8042.dumbkbd [HW] Pretend that controller can only read data from
1111 keyboard and cannot control its state
1112 (Don't attempt to blink the leds)
1113 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
1114 i8042.nokbd [HW] Don't check/create keyboard port
1115 i8042.noloop [HW] Disable the AUX Loopback command while probing
1117 i8042.nomux [HW] Don't check presence of an active multiplexing
1119 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1121 i8042.notimeout [HW] Ignore timeout condition signalled by controller
1122 i8042.reset [HW] Reset the controller during init and cleanup
1123 i8042.unlock [HW] Unlock (ignore) the keylock
1127 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
1128 indicates that the driver is running on unsupported
1130 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
1131 does not match list of supported models.
1133 [HW] Report power status in /proc/i8k
1134 (disabled by default)
1135 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
1138 i915.invert_brightness=
1139 [DRM] Invert the sense of the variable that is used to
1140 set the brightness of the panel backlight. Normally a
1141 brightness value of 0 indicates backlight switched off,
1142 and the maximum of the brightness value sets the backlight
1143 to maximum brightness. If this parameter is set to 0
1144 (default) and the machine requires it, or this parameter
1145 is set to 1, a brightness value of 0 sets the backlight
1146 to maximum brightness, and the maximum of the brightness
1147 value switches the backlight off.
1148 -1 -- never invert brightness
1149 0 -- machine default
1150 1 -- force brightness inversion
1153 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1155 ide-core.nodma= [HW] (E)IDE subsystem
1156 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1157 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1158 .cdrom .chs .ignore_cable are additional options
1159 See Documentation/ide/ide.txt.
1161 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1162 Claim all unknown PCI IDE storage controllers.
1165 Format: idle=poll, idle=halt, idle=nomwait
1166 Poll forces a polling idle loop that can slightly
1167 improve the performance of waking up a idle CPU, but
1168 will use a lot of power and make the system run hot.
1170 idle=halt: Halt is forced to be used for CPU idle.
1171 In such case C2/C3 won't be used again.
1172 idle=nomwait: Disable mwait for CPU C-states
1174 ignore_loglevel [KNL]
1175 Ignore loglevel setting - this will print /all/
1176 kernel messages to the console. Useful for debugging.
1177 We also add it as printk module parameter, so users
1178 could change it dynamically, usually by
1179 /sys/module/printk/parameters/ignore_loglevel.
1181 ihash_entries= [KNL]
1182 Set number of hash buckets for inode cache.
1184 ima_appraise= [IMA] appraise integrity measurements
1185 Format: { "off" | "enforce" | "fix" }
1188 ima_appraise_tcb [IMA]
1189 The builtin appraise policy appraises all files
1193 Format: { md5 | sha1 | rmd160 | sha256 | sha384
1197 The list of supported hash algorithms is defined
1198 in crypto/hash_info.h.
1201 Load a policy which meets the needs of the Trusted
1202 Computing Base. This means IMA will measure all
1203 programs exec'd, files mmap'd for exec, and all files
1204 opened for read by uid=0.
1207 Select one of defined IMA measurements template formats.
1208 Formats: { "ima" | "ima-ng" }
1213 Run specified binary instead of /sbin/init as init
1216 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1217 for working out where the kernel is dying during
1220 initrd= [BOOT] Specify the location of the initial ramdisk
1222 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1225 int_pln_enable [x86] Enable power limit notification interrupt
1227 integrity_audit=[IMA]
1228 Format: { "0" | "1" }
1229 0 -- basic integrity auditing messages. (Default)
1230 1 -- additional integrity auditing messages.
1232 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1234 Enable intel iommu driver.
1236 Disable intel iommu driver.
1237 igfx_off [Default Off]
1238 By default, gfx is mapped as normal device. If a gfx
1239 device has a dedicated DMAR unit, the DMAR unit is
1240 bypassed by not enabling DMAR with this option. In
1241 this case, gfx device will use physical address for
1244 With this option iommu will not optimize to look
1245 for io virtual address below 32-bit forcing dual
1246 address cycle on pci bus for cards supporting greater
1247 than 32-bit addressing. The default is to look
1248 for translation below 32-bit and if not available
1249 then look in the higher range.
1250 strict [Default Off]
1251 With this option on every unmap_single operation will
1252 result in a hardware IOTLB flush operation as opposed
1253 to batching them for performance.
1254 sp_off [Default Off]
1255 By default, super page will be supported if Intel IOMMU
1256 has the capability. With this option, super page will
1259 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1260 0 disables intel_idle and fall back on acpi_idle.
1261 1 to 6 specify maximum depth of C-state.
1265 Do not enable intel_pstate as the default
1266 scaling driver for the supported processors
1268 intremap= [X86-64, Intel-IOMMU]
1269 on enable Interrupt Remapping (default)
1270 off disable Interrupt Remapping
1271 nosid disable Source ID checking
1273 BIOS x2APIC opt-out request will be ignored
1275 iomem= Disable strict checking of access to MMIO memory
1276 strict regions from userspace.
1293 io7= [HW] IO7 for Marvel based alpha systems
1294 See comment before marvel_specify_io7 in
1295 arch/alpha/kernel/core_marvel.c.
1297 io_delay= [X86] I/O delay method
1299 Standard port 0x80 based delay
1301 Alternate port 0xed based delay (needed on some systems)
1303 Simple two microseconds delay
1308 See Documentation/filesystems/nfs/nfsroot.txt.
1310 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1311 See comment before ip2_setup() in
1312 drivers/char/ip2/ip2base.c.
1315 When an interrupt is not handled search all handlers
1316 for it. Intended to get systems with badly broken
1320 When an interrupt is not handled search all handlers
1321 for it. Also check all handlers each timer
1322 interrupt. Intended to get systems with badly broken
1326 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1328 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1330 <cpu number>,...,<cpu number>
1332 <cpu number>-<cpu number>
1333 (must be a positive range in ascending order)
1335 <cpu number>,...,<cpu number>-<cpu number>
1337 This option can be used to specify one or more CPUs
1338 to isolate from the general SMP balancing and scheduling
1339 algorithms. You can move a process onto or off an
1340 "isolated" CPU via the CPU affinity syscalls or cpuset.
1341 <cpu number> begins at 0 and the maximum value is
1342 "number of CPUs in system - 1".
1344 This option is the preferred way to isolate CPUs. The
1345 alternative -- manually setting the CPU mask of all
1346 tasks in the system -- can cause problems and
1347 suboptimal load balancer performance.
1351 ivrs_ioapic [HW,X86_64]
1352 Provide an override to the IOAPIC-ID<->DEVICE-ID
1353 mapping provided in the IVRS ACPI table. For
1354 example, to map IOAPIC-ID decimal 10 to
1355 PCI device 00:14.0 write the parameter as:
1356 ivrs_ioapic[10]=00:14.0
1358 ivrs_hpet [HW,X86_64]
1359 Provide an override to the HPET-ID<->DEVICE-ID
1360 mapping provided in the IVRS ACPI table. For
1361 example, to map HPET-ID decimal 0 to
1362 PCI device 00:14.0 write the parameter as:
1363 ivrs_hpet[0]=00:14.0
1365 js= [HW,JOY] Analog joystick
1366 See Documentation/input/joystick.txt.
1370 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1371 specifies the amount of memory usable by the kernel
1372 for non-movable allocations. The requested amount is
1373 spread evenly throughout all nodes in the system. The
1374 remaining memory in each node is used for Movable
1375 pages. In the event, a node is too small to have both
1376 kernelcore and Movable pages, kernelcore pages will
1377 take priority and other nodes will have a larger number
1378 of Movable pages. The Movable zone is used for the
1379 allocation of pages that may be reclaimed or moved
1380 by the page migration subsystem. This means that
1381 HugeTLB pages may not be allocated from this zone.
1382 Note that allocations like PTEs-from-HighMem still
1383 use the HighMem zone if it exists, and the Normal
1384 zone if it does not.
1386 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1387 Format: <Controller#>[,poll interval]
1388 The controller # is the number of the ehci usb debug
1389 port as it is probed via PCI. The poll interval is
1390 optional and is the number seconds in between
1391 each poll cycle to the debug port in case you need
1392 the functionality for interrupting the kernel with
1393 gdb or control-c on the dbgp connection. When
1394 not using this parameter you use sysrq-g to break into
1395 the kernel debugger.
1397 kgdboc= [KGDB,HW] kgdb over consoles.
1398 Requires a tty driver that supports console polling,
1399 or a supported polling keyboard driver (non-usb).
1400 Serial only format: <serial_device>[,baud]
1401 keyboard only format: kbd
1402 keyboard and serial format: kbd,<serial_device>[,baud]
1403 Optional Kernel mode setting:
1404 kms, kbd format: kms,kbd
1405 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1407 kgdbwait [KGDB] Stop kernel execution and enter the
1408 kernel debugger at the earliest opportunity.
1410 kmac= [MIPS] korina ethernet MAC address.
1411 Configure the RouterBoard 532 series on-chip
1412 Ethernet adapter MAC address.
1414 kmemleak= [KNL] Boot-time kmemleak enable/disable
1415 Valid arguments: on, off
1418 kstack=N [X86] Print N words from the kernel stack
1421 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1422 Default is 0 (don't ignore, but inject #GP)
1424 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1428 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1429 Default is 1 (enabled)
1431 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1433 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1435 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1436 (virtualized MMU) support on capable Intel chips.
1437 Default is 1 (enabled)
1439 kvm-intel.emulate_invalid_guest_state=
1440 [KVM,Intel] Enable emulation of invalid guest states
1441 Default is 0 (disabled)
1443 kvm-intel.flexpriority=
1444 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1445 Default is 1 (enabled)
1448 [KVM,Intel] Enable VMX nesting (nVMX).
1449 Default is 0 (disabled)
1451 kvm-intel.unrestricted_guest=
1452 [KVM,Intel] Disable unrestricted guest feature
1453 (virtualized real and unpaged mode) on capable
1454 Intel chips. Default is 1 (enabled)
1456 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1457 feature (tagged TLBs) on capable Intel chips.
1458 Default is 1 (enabled)
1464 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1467 lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
1468 value for LAPIC timer one-shot implementation. Default
1469 back to the programmable timer unit in the LAPIC.
1471 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1474 libata.dma= [LIBATA] DMA control
1475 libata.dma=0 Disable all PATA and SATA DMA
1476 libata.dma=1 PATA and SATA Disk DMA only
1477 libata.dma=2 ATAPI (CDROM) DMA only
1478 libata.dma=4 Compact Flash DMA only
1479 Combinations also work, so libata.dma=3 enables DMA
1480 for disks and CDROMs, but not CFs.
1482 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1483 libata.ignore_hpa=0 keep BIOS limits (default)
1484 libata.ignore_hpa=1 ignore limits, using full disk
1486 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1490 libata.force= [LIBATA] Force configurations. The format is comma
1491 separated list of "[ID:]VAL" where ID is
1492 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1493 matching port, link or device. Basically, it matches
1494 the ATA ID string printed on console by libata. If
1495 the whole ID part is omitted, the last PORT and DEVICE
1496 values are used. If ID hasn't been specified yet, the
1497 configuration applies to all ports, links and devices.
1499 If only DEVICE is omitted, the parameter applies to
1500 the port and all links and devices behind it. DEVICE
1501 number of 0 either selects the first device or the
1502 first fan-out link behind PMP device. It does not
1503 select the host link. DEVICE number of 15 selects the
1504 host link and device attached to it.
1506 The VAL specifies the configuration to force. As long
1507 as there's no ambiguity shortcut notation is allowed.
1508 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1509 The following configurations can be forced.
1511 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1512 Any ID with matching PORT is used.
1514 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1516 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1517 udma[/][16,25,33,44,66,100,133] notation is also
1520 * [no]ncq: Turn on or off NCQ.
1522 * nohrst, nosrst, norst: suppress hard, soft
1525 * rstonce: only attempt one reset during
1526 hot-unplug link recovery
1528 * dump_id: dump IDENTIFY data.
1530 * atapi_dmadir: Enable ATAPI DMADIR bridge support
1532 * disable: Disable this device.
1534 If there are multiple matching configurations changing
1535 the same attribute, the last one is used.
1537 memblock=debug [KNL] Enable memblock debug messages.
1539 load_ramdisk= [RAM] List of ramdisks to load from floppy
1540 See Documentation/blockdev/ramdisk.txt.
1542 lockd.nlm_grace_period=P [NFS] Assign grace period.
1545 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1548 lockd.nlm_timeout=T [NFS] Assign timeout value.
1551 lockd.nlm_udpport=M [NFS] Assign UDP port.
1554 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1557 loglevel= All Kernel Messages with a loglevel smaller than the
1558 console loglevel will be printed to the console. It can
1559 also be changed with klogd or other programs. The
1560 loglevels are defined as follows:
1562 0 (KERN_EMERG) system is unusable
1563 1 (KERN_ALERT) action must be taken immediately
1564 2 (KERN_CRIT) critical conditions
1565 3 (KERN_ERR) error conditions
1566 4 (KERN_WARNING) warning conditions
1567 5 (KERN_NOTICE) normal but significant condition
1568 6 (KERN_INFO) informational
1569 7 (KERN_DEBUG) debug-level messages
1571 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1572 in bytes. n must be a power of two. The default
1573 size is set in the kernel config file.
1575 logo.nologo [FB] Disables display of the built-in Linux logo.
1576 This may be used to provide more screen space for
1577 kernel log messages and is useful when debugging
1578 kernel boot problems.
1580 lp=0 [LP] Specify parallel ports to use, e.g,
1581 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1582 lp=reset first parallel port). 'lp=0' disables the
1583 lp=auto printer driver. 'lp=reset' (which can be
1584 specified in addition to the ports) causes
1585 attached printers to be reset. Using
1586 lp=port1,port2,... specifies the parallel ports
1587 to associate lp devices with, starting with
1588 lp0. A port specification may be 'none' to skip
1589 that lp device, or a parport name such as
1590 'parport0'. Specifying 'lp=auto' instead of a
1591 port specification list means that device IDs
1592 from each port should be examined, to see if
1593 an IEEE 1284-compliant printer is attached; if
1594 so, the driver will manage that printer.
1595 See also header of drivers/char/lp.c.
1598 Sets loops_per_jiffy to given constant, thus avoiding
1599 time-consuming boot-time autodetection (up to 250 ms per
1600 CPU). 0 enables autodetection (default). To determine
1601 the correct value for your kernel, boot with normal
1602 autodetection and see what value is printed. Note that
1603 on SMP systems the preset will be applied to all CPUs,
1604 which is likely to cause problems if your CPUs need
1605 significantly divergent settings. An incorrect value
1606 will cause delays in the kernel to be wrong, leading to
1607 unpredictable I/O errors and other breakage. Although
1608 unlikely, in the extreme case this might damage your
1612 Format: <io>,<irq>,<dma>
1614 machvec= [IA-64] Force the use of a particular machine-vector
1615 (machvec) in a generic kernel.
1616 Example: machvec=hpzx1_swiotlb
1618 machtype= [Loongson] Share the same kernel image file between different
1620 Example: machtype=lemote-yeeloong-2f-7inch
1622 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1623 than or equal to this physical address is ignored.
1625 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1626 should make use of. maxcpus=n : n >= 0 limits the
1627 kernel to using 'n' processors. n=0 is a special case,
1628 it is equivalent to "nosmp", which also disables
1631 max_loop= [LOOP] The number of loop block devices that get
1632 (loop.max_loop) unconditionally pre-created at init time. The default
1633 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1634 of statically allocating a predefined number, loop
1635 devices can be requested on-demand with the
1636 /dev/loop-control interface.
1638 mce [X86-32] Machine Check Exception
1640 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1642 md= [HW] RAID subsystems devices and level
1643 See Documentation/md.txt.
1646 Format: <first>,<last>
1647 Specifies range of consoles to be captured by the MDA.
1649 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1650 Amount of memory to be used when the kernel is not able
1651 to see the whole system memory or for test.
1652 [X86] Work as limiting max address. Use together
1653 with memmap= to avoid physical address space collisions.
1654 Without memmap= PCI devices could be placed at addresses
1655 belonging to unused RAM.
1657 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1661 [KNL,SH] Allow user to override the default size for
1662 per-device physically contiguous DMA buffers.
1664 memmap=exactmap [KNL,X86] Enable setting of an exact
1665 E820 memory map, as specified by the user.
1666 Such memmap=exactmap lines can be constructed based on
1667 BIOS output or other requirements. See the memmap=nn@ss
1670 memmap=nn[KMG]@ss[KMG]
1671 [KNL] Force usage of a specific region of memory
1672 Region of memory to be used, from ss to ss+nn.
1674 memmap=nn[KMG]#ss[KMG]
1675 [KNL,ACPI] Mark specific memory as ACPI data.
1676 Region of memory to be used, from ss to ss+nn.
1678 memmap=nn[KMG]$ss[KMG]
1679 [KNL,ACPI] Mark specific memory as reserved.
1680 Region of memory to be used, from ss to ss+nn.
1681 Example: Exclude memory from 0x18690000-0x1869ffff
1682 memmap=64K$0x18690000
1684 memmap=0x10000$0x18690000
1686 memory_corruption_check=0/1 [X86]
1687 Some BIOSes seem to corrupt the first 64k of
1688 memory when doing things like suspend/resume.
1689 Setting this option will scan the memory
1690 looking for corruption. Enabling this will
1691 both detect corruption and prevent the kernel
1692 from using the memory being corrupted.
1693 However, its intended as a diagnostic tool; if
1694 repeatable BIOS-originated corruption always
1695 affects the same memory, you can use memmap=
1696 to prevent the kernel from using that memory.
1698 memory_corruption_check_size=size [X86]
1699 By default it checks for corruption in the low
1700 64k, making this memory unavailable for normal
1701 use. Use this parameter to scan for
1702 corruption in more or less memory.
1704 memory_corruption_check_period=seconds [X86]
1705 By default it checks for corruption every 60
1706 seconds. Use this parameter to check at some
1707 other rate. 0 disables periodic checking.
1709 memtest= [KNL,X86] Enable memtest
1711 default : 0 <disable>
1712 Specifies the number of memtest passes to be
1713 performed. Each pass selects another test
1714 pattern from a given set of patterns. Memtest
1715 fills the memory with this pattern, validates
1716 memory contents and reserves bad memory
1717 regions that are detected.
1719 meye.*= [HW] Set MotionEye Camera parameters
1720 See Documentation/video4linux/meye.txt.
1722 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1723 Multi-Function General Purpose Timers on AMD Geode
1726 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1727 the BIOS has incorrectly applied a workaround. TinyBIOS
1728 version 0.98 is known to be affected, 0.99 fixes the
1729 problem by letting the user disable the workaround.
1733 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1734 physical address is ignored.
1736 mini2440= [ARM,HW,KNL]
1737 Format:[0..2][b][c][t]
1739 MINI2440 configuration specification:
1740 0 - The attached screen is the 3.5" TFT
1741 1 - The attached screen is the 7" TFT
1742 2 - The VGA Shield is attached (1024x768)
1743 Leaving out the screen size parameter will not load
1744 the TFT driver, and the framebuffer will be left
1746 b - Enable backlight. The TFT backlight pin will be
1747 linked to the kernel VESA blanking code and a GPIO
1748 LED. This parameter is not necessary when using the
1750 c - Enable the s3c camera interface.
1751 t - Reserved for enabling touchscreen support. The
1752 touchscreen support is not enabled in the mainstream
1753 kernel as of 2.6.30, a preliminary port can be found
1754 in the "bleeding edge" mini2440 support kernel at
1755 http://repo.or.cz/w/linux-2.6/mini2440.git
1758 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1759 parameter allows control of the logging verbosity for
1760 the additional memory initialisation checks. A value
1761 of 0 disables mminit logging and a level of 4 will
1762 log everything. Information is printed at KERN_DEBUG
1763 so loglevel=8 may also need to be specified.
1766 [KNL] When CONFIG_MODULE_SIG is set, this means that
1767 modules without (valid) signatures will fail to load.
1768 Note that if CONFIG_MODULE_SIG_FORCE is set, that
1769 is always true, so this option does nothing.
1772 [MOUSE] Maximum time between finger touching and
1773 leaving touchpad surface for touch to be considered
1774 a tap and be reported as a left button click (for
1775 touchpads working in absolute mode only).
1777 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1778 reporting absolute coordinates, such as tablets
1779 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1780 reporting absolute coordinates, such as tablets
1782 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1783 is similar to kernelcore except it specifies the
1784 amount of memory used for migratable allocations.
1785 If both kernelcore and movablecore is specified,
1786 then kernelcore will be at *least* the specified
1787 value but may be more. If movablecore on its own
1788 is specified, the administrator must be careful
1789 that the amount of memory usable for all allocations
1792 movable_node [KNL,X86] Boot-time switch to enable the effects
1793 of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
1795 MTD_Partition= [MTD]
1796 Format: <name>,<region-number>,<size>,<offset>
1798 MTD_Region= [MTD] Format:
1799 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1802 See drivers/mtd/cmdlinepart.c.
1804 multitce=off [PPC] This parameter disables the use of the pSeries
1805 firmware feature for updating multiple TCE entries
1808 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1810 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1812 boundary - index of last SLC block on Flex-OneNAND.
1813 The remaining blocks are configured as MLC blocks.
1814 lock - Configure if Flex-OneNAND boundary should be locked.
1815 Once locked, the boundary cannot be changed.
1816 1 indicates lock status, 0 indicates unlock status.
1819 ARM/S3C2412 JIVE boot control
1821 See arch/arm/mach-s3c2412/mach-jive.c
1823 mtouchusb.raw_coordinates=
1824 [HW] Make the MicroTouch USB driver use raw coordinates
1825 ('y', default) or cooked coordinates ('n')
1827 mtrr_chunk_size=nn[KMG] [X86]
1828 used for mtrr cleanup. It is largest continuous chunk
1829 that could hold holes aka. UC entries.
1831 mtrr_gran_size=nn[KMG] [X86]
1832 Used for mtrr cleanup. It is granularity of mtrr block.
1834 Large value could prevent small alignment from
1837 mtrr_spare_reg_nr=n [X86]
1839 Range: 0,7 : spare reg number
1841 Used for mtrr cleanup. It is spare mtrr entries number.
1842 Set to 2 or more if your graphical card needs more.
1844 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1846 netdev= [NET] Network devices parameters
1847 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1848 Note that mem_start is often overloaded to mean
1849 something different and driver-specific.
1850 This usage is only documented in each driver source
1854 [NETFILTER] Enable connection tracking flow accounting
1855 0 to disable accounting
1856 1 to enable accounting
1859 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1860 See Documentation/filesystems/nfs/nfsroot.txt.
1862 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1863 See Documentation/filesystems/nfs/nfsroot.txt.
1865 nfsrootdebug [NFS] enable nfsroot debugging messages.
1866 See Documentation/filesystems/nfs/nfsroot.txt.
1868 nfs.callback_tcpport=
1869 [NFS] set the TCP port on which the NFSv4 callback
1870 channel should listen.
1873 [NFS] sets the pathname to the program which is used
1874 to update the NFS client cache entries.
1876 nfs.cache_getent_timeout=
1877 [NFS] sets the timeout after which an attempt to
1878 update a cache entry is deemed to have failed.
1880 nfs.idmap_cache_timeout=
1881 [NFS] set the maximum lifetime for idmapper cache
1885 [NFS] enable 64-bit inode numbers.
1886 If zero, the NFS client will fake up a 32-bit inode
1887 number for the readdir() and stat() syscalls instead
1888 of returning the full 64-bit number.
1889 The default is to return 64-bit inode numbers.
1891 nfs.max_session_slots=
1892 [NFSv4.1] Sets the maximum number of session slots
1893 the client will attempt to negotiate with the server.
1894 This limits the number of simultaneous RPC requests
1895 that the client can send to the NFSv4.1 server.
1896 Note that there is little point in setting this
1897 value higher than the max_tcp_slot_table_limit.
1899 nfs.nfs4_disable_idmapping=
1900 [NFSv4] When set to the default of '1', this option
1901 ensures that both the RPC level authentication
1902 scheme and the NFS level operations agree to use
1903 numeric uids/gids if the mount is using the
1904 'sec=sys' security flavour. In effect it is
1905 disabling idmapping, which can make migration from
1906 legacy NFSv2/v3 systems to NFSv4 easier.
1907 Servers that do not support this mode of operation
1908 will be autodetected by the client, and it will fall
1909 back to using the idmapper.
1910 To turn off this behaviour, set the value to '0'.
1912 [NFS4] Specify an additional fixed unique ident-
1913 ification string that NFSv4 clients can insert into
1914 their nfs_client_id4 string. This is typically a
1915 UUID that is generated at system install time.
1917 nfs.send_implementation_id =
1918 [NFSv4.1] Send client implementation identification
1919 information in exchange_id requests.
1920 If zero, no implementation identification information
1922 The default is to send the implementation identification
1925 nfs.recover_lost_locks =
1926 [NFSv4] Attempt to recover locks that were lost due
1927 to a lease timeout on the server. Please note that
1928 doing this risks data corruption, since there are
1929 no guarantees that the file will remain unchanged
1930 after the locks are lost.
1931 If you want to enable the kernel legacy behaviour of
1932 attempting to recover these locks, then set this
1934 The default parameter value of '0' causes the kernel
1935 not to attempt recovery of lost locks.
1937 nfsd.nfs4_disable_idmapping=
1938 [NFSv4] When set to the default of '1', the NFSv4
1939 server will return only numeric uids and gids to
1940 clients using auth_sys, and will accept numeric uids
1941 and gids from such clients. This is intended to ease
1942 migration from NFSv2/v3.
1944 objlayoutdriver.osd_login_prog=
1945 [NFS] [OBJLAYOUT] sets the pathname to the program which
1946 is used to automatically discover and login into new
1947 osd-targets. Please see:
1948 Documentation/filesystems/pnfs.txt for more explanations
1950 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1951 when a NMI is triggered.
1952 Format: [state][,regs][,debounce][,die]
1954 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1955 Format: [panic,][nopanic,][num]
1957 0 - turn nmi_watchdog off
1958 When panic is specified, panic when an NMI watchdog
1959 timeout occurs (or 'nopanic' to override the opposite
1961 This is useful when you use a panic=... timeout and
1962 need the box quickly up again.
1964 netpoll.carrier_timeout=
1965 [NET] Specifies amount of time (in seconds) that
1966 netpoll should wait for a carrier. By default netpoll
1969 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1970 emulation library even if a 387 maths coprocessor
1974 [HW] Never suspend the console
1975 Disable suspending of consoles during suspend and
1976 hibernate operations. Once disabled, debugging
1977 messages can reach various consoles while the rest
1978 of the system is being put to sleep (ie, while
1979 debugging driver suspend/resume hooks). This may
1980 not work reliably with all consoles, but is known
1981 to work with serial and VGA consoles.
1982 To facilitate more flexible debugging, we also add
1983 console_suspend, a printk module parameter to control
1984 it. Users could use console_suspend (usually
1985 /sys/module/printk/parameters/console_suspend) to
1986 turn on/off it dynamically.
1988 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1989 caches in the slab allocator. Saves per-node memory,
1990 but will impact performance.
1994 noapic [SMP,APIC] Tells the kernel to not make use of any
1995 IOAPICs that may be present in the system.
1997 noautogroup Disable scheduler automatic task group creation.
1999 nobats [PPC] Do not use BATs for mapping kernel lowmem
2000 on "Classic" PPC cores.
2004 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
2006 nodelayacct [KNL] Disable per-task delay accounting
2008 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
2010 nodsp [SH] Disable hardware DSP at boot time.
2012 noefi [X86] Disable EFI runtime services support.
2017 On X86-32 available only on PAE configured kernels.
2018 noexec=on: enable non-executable mappings (default)
2019 noexec=off: disable non-executable mappings
2022 Disable SMAP (Supervisor Mode Access Prevention)
2023 even if it is supported by processor.
2026 Disable SMEP (Supervisor Mode Execution Prevention)
2027 even if it is supported by processor.
2030 This affects only 32-bit executables.
2031 noexec32=on: enable non-executable mappings (default)
2032 read doesn't imply executable mappings
2033 noexec32=off: disable non-executable mappings
2034 read implies executable mappings
2036 nofpu [SH] Disable hardware FPU at boot time.
2038 nofxsr [BUGS=X86-32] Disables x86 floating point extended
2039 register save and restore. The kernel will only save
2040 legacy floating-point registers on task switch.
2042 noxsave [BUGS=X86] Disables x86 extended register state save
2043 and restore using xsave. The kernel will fallback to
2044 enabling legacy floating-point and sse state.
2047 on enable eager fpu restore
2048 off disable eager fpu restore
2049 auto selects the default scheme, which automatically
2050 enables eagerfpu restore for xsaveopt.
2052 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2053 wfi(ARM) instruction doesn't work correctly and not to
2054 use it. This is also useful when using JTAG debugger.
2056 no_file_caps Tells the kernel not to honor file capabilities. The
2057 only way then for a file to be executed with privilege
2058 is to be setuid root or executed by root.
2060 nohalt [IA-64] Tells the kernel not to use the power saving
2061 function PAL_HALT_LIGHT when idle. This increases
2062 power-consumption. On the positive side, it reduces
2063 interrupt wake-up latency, which may improve performance
2064 in certain environments such as networked servers or
2067 nohz= [KNL] Boottime enable/disable dynamic ticks
2068 Valid arguments: on, off
2071 nohz_full= [KNL,BOOT]
2072 In kernels built with CONFIG_NO_HZ_FULL=y, set
2073 the specified list of CPUs whose tick will be stopped
2074 whenever possible. The boot CPU will be forced outside
2075 the range to maintain the timekeeping.
2076 The CPUs in this range must also be included in the
2079 noiotrap [SH] Disables trapped I/O port accesses.
2081 noirqdebug [X86-32] Disables the code which attempts to detect and
2082 disable unhandled interrupt sources.
2084 no_timer_check [X86,APIC] Disables the code which tests for
2085 broken timer IRQ sources.
2087 noisapnp [ISAPNP] Disables ISA PnP code.
2089 noinitrd [RAM] Tells the kernel not to load any configured
2092 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
2094 [Deprecated - use intremap=off]
2098 nojitter [IA-64] Disables jitter checking for ITC timers.
2100 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
2102 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
2105 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
2106 steal time is computed, but won't influence scheduler
2109 nolapic [X86-32,APIC] Do not enable or use the local APIC.
2111 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
2113 noltlbs [PPC] Do not use large page/tlb entries for kernel
2114 lowmem mapping on PPC40x.
2116 nomca [IA-64] Disable machine check abort handling
2118 nomce [X86-32] Machine Check Exception
2120 nomfgpt [X86-32] Disable Multi-Function General Purpose
2121 Timer usage (for AMD Geode machines).
2123 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
2124 shutdown the other cpus. Instead use the REBOOT_VECTOR
2127 nomodule Disable module load
2129 nopat [X86] Disable PAT (page attribute table extension of
2130 pagetables) support.
2132 norandmaps Don't use address space randomization. Equivalent to
2133 echo 0 > /proc/sys/kernel/randomize_va_space
2135 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
2137 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
2138 with UP alternatives
2140 nordrand [X86] Disable the direct use of the RDRAND
2141 instruction even if it is supported by the
2142 processor. RDRAND is still available to user
2145 noresume [SWSUSP] Disables resume and restores original swap
2148 no-scroll [VGA] Disables scrollback.
2149 This is required for the Braillex ib80-piezo Braille
2150 reader made by F.H. Papenmeier (Germany).
2154 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
2156 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
2157 and disable the IO APIC. legacy for "maxcpus=0".
2159 nosoftlockup [KNL] Disable the soft-lockup detector.
2161 nosync [HW,M68K] Disables sync negotiation for all devices.
2163 notsc [BUGS=X86-32] Disable Time Stamp Counter
2165 nousb [USB] Disable the USB subsystem
2167 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
2171 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
2173 cpu0_hotplug [X86] Turn on CPU0 hotplug feature when
2174 CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2175 Some features depend on CPU0. Known dependencies are:
2176 1. Resume from suspend/hibernate depends on CPU0.
2177 Suspend/hibernate will fail if CPU0 is offline and you
2178 need to online CPU0 before suspend/hibernate.
2179 2. PIC interrupts also depend on CPU0. CPU0 can't be
2180 removed if a PIC interrupt is detected.
2181 It's said poweroff/reboot may depend on CPU0 on some
2182 machines although I haven't seen such issues so far
2183 after CPU0 is offline on a few tested machines.
2184 If the dependencies are under your control, you can
2185 turn on cpu0_hotplug.
2187 nptcg= [IA-64] Override max number of concurrent global TLB
2188 purges which is reported from either PAL_VM_SUMMARY or
2191 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
2192 could support. nr_cpus=n : n >= 1 limits the kernel to
2193 supporting 'n' processors. Later in runtime you can not
2194 use hotplug cpu feature to put more cpu back to online.
2195 just like you compile the kernel NR_CPUS=n
2197 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
2199 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
2200 Allowed values are enable and disable
2202 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2203 one of ['zone', 'node', 'default'] can be specified
2204 This can be set from sysctl after boot.
2205 See Documentation/sysctl/vm.txt for details.
2207 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
2208 See Documentation/debugging-via-ohci1394.txt for more
2211 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2212 Rather than timing out after 20 ms if an EC
2213 command is not properly ACKed, override the length
2214 of the timeout. We have interrupts disabled while
2215 waiting for the ACK, so if this is set too high
2216 interrupts *may* be lost!
2218 omap_mux= [OMAP] Override bootloader pin multiplexing.
2219 Format: <mux_mode0.mode_name=value>...
2220 For example, to override I2C bus2:
2221 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2223 oprofile.timer= [HW]
2224 Use timer interrupt instead of performance counters
2226 oprofile.cpu_type= Force an oprofile cpu type
2227 This might be useful if you have an older oprofile
2228 userland or if you want common events.
2229 Format: { arch_perfmon }
2230 arch_perfmon: [X86] Force use of architectural
2231 perfmon on Intel CPUs instead of the
2232 CPU specific event set.
2233 timer: [X86] Force use of architectural NMI
2234 timer mode (see also oprofile.timer
2235 for generic hr timer mode)
2236 [s390] Force legacy basic mode sampling
2237 (report cpu_type "timer")
2239 oops=panic Always panic on oopses. Default is to just kill the
2240 process, but there is a small probability of
2241 deadlocking the machine.
2242 This will also cause panics on machine check exceptions.
2243 Useful together with panic=30 to trigger a reboot.
2246 See Documentation/sound/oss/oss-parameters.txt
2248 panic= [KNL] Kernel behaviour on panic: delay <timeout>
2249 timeout > 0: seconds before rebooting
2250 timeout = 0: wait forever
2251 timeout < 0: reboot immediately
2254 parkbd.port= [HW] Parallel port number the keyboard adapter is
2255 connected to, default is 0.
2257 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
2258 0 for XT, 1 for AT (default is AT).
2261 parport= [HW,PPT] Specify parallel ports. 0 disables.
2262 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2263 Use 'auto' to force the driver to use any
2264 IRQ/DMA settings detected (the default is to
2265 ignore detected IRQ/DMA settings because of
2266 possible conflicts). You can specify the base
2267 address, IRQ, and DMA settings; IRQ and DMA
2268 should be numbers, or 'auto' (for using detected
2269 settings on that particular port), or 'nofifo'
2270 (to avoid using a FIFO even if it is detected).
2271 Parallel ports are assigned in the order they
2272 are specified on the command line, starting
2275 parport_init_mode= [HW,PPT]
2276 Configure VIA parallel port to operate in
2277 a specific mode. This is necessary on Pegasos
2278 computer where firmware has no options for setting
2279 up parallel port mode and sets it to spp.
2280 Currently this function knows 686a and 8231 chips.
2281 Format: [spp|ps2|epp|ecp|ecpepp]
2284 Halt all CPUs after the first oops has been printed for
2285 the specified number of seconds. This is to be used if
2286 your oopses keep scrolling off the screen.
2291 See header of drivers/block/paride/pcd.c.
2292 See also Documentation/blockdev/paride.txt.
2294 pci=option[,option...] [PCI] various PCI subsystem options:
2295 earlydump [X86] dump PCI config space before the kernel
2297 off [X86] don't probe for the PCI bus
2298 bios [X86-32] force use of PCI BIOS, don't access
2299 the hardware directly. Use this if your machine
2300 has a non-standard PCI host bridge.
2301 nobios [X86-32] disallow use of PCI BIOS, only direct
2302 hardware access methods are allowed. Use this
2303 if you experience crashes upon bootup and you
2304 suspect they are caused by the BIOS.
2305 conf1 [X86] Force use of PCI Configuration
2307 conf2 [X86] Force use of PCI Configuration
2309 noaer [PCIE] If the PCIEAER kernel config parameter is
2310 enabled, this kernel boot option can be used to
2311 disable the use of PCIE advanced error reporting.
2312 nodomains [PCI] Disable support for multiple PCI
2313 root domains (aka PCI segments, in ACPI-speak).
2314 nommconf [X86] Disable use of MMCONFIG for PCI
2316 check_enable_amd_mmconf [X86] check for and enable
2317 properly configured MMIO access to PCI
2318 config space on AMD family 10h CPU
2319 nomsi [MSI] If the PCI_MSI kernel config parameter is
2320 enabled, this kernel boot option can be used to
2321 disable the use of MSI interrupts system-wide.
2322 noioapicquirk [APIC] Disable all boot interrupt quirks.
2323 Safety option to keep boot IRQs enabled. This
2324 should never be necessary.
2325 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2326 primary IO-APIC for bridges that cannot disable
2327 boot IRQs. This fixes a source of spurious IRQs
2328 when the system masks IRQs.
2329 noioapicreroute [APIC] Disable workaround that uses the
2330 boot IRQ equivalent of an IRQ that connects to
2331 a chipset where boot IRQs cannot be disabled.
2332 The opposite of ioapicreroute.
2333 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2334 routing table. These calls are known to be buggy
2335 on several machines and they hang the machine
2336 when used, but on other computers it's the only
2337 way to get the interrupt routing table. Try
2338 this option if the kernel is unable to allocate
2339 IRQs or discover secondary PCI buses on your
2341 rom [X86] Assign address space to expansion ROMs.
2342 Use with caution as certain devices share
2343 address decoders between ROMs and other
2345 norom [X86] Do not assign address space to
2346 expansion ROMs that do not already have
2347 BIOS assigned address ranges.
2348 nobar [X86] Do not assign address space to the
2349 BARs that weren't assigned by the BIOS.
2350 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2351 assigned automatically to PCI devices. You can
2352 make the kernel exclude IRQs of your ISA cards
2354 pirqaddr=0xAAAAA [X86] Specify the physical address
2355 of the PIRQ table (normally generated
2356 by the BIOS) if it is outside the
2357 F0000h-100000h range.
2358 lastbus=N [X86] Scan all buses thru bus #N. Can be
2359 useful if the kernel is unable to find your
2360 secondary buses and you want to tell it
2361 explicitly which ones they are.
2362 assign-busses [X86] Always assign all PCI bus
2363 numbers ourselves, overriding
2364 whatever the firmware may have done.
2365 usepirqmask [X86] Honor the possible IRQ mask stored
2366 in the BIOS $PIR table. This is needed on
2367 some systems with broken BIOSes, notably
2368 some HP Pavilion N5400 and Omnibook XE3
2369 notebooks. This will have no effect if ACPI
2370 IRQ routing is enabled.
2371 noacpi [X86] Do not use ACPI for IRQ routing
2372 or for PCI scanning.
2373 use_crs [X86] Use PCI host bridge window information
2374 from ACPI. On BIOSes from 2008 or later, this
2375 is enabled by default. If you need to use this,
2376 please report a bug.
2377 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2378 If you need to use this, please report a bug.
2379 routeirq Do IRQ routing for all PCI devices.
2380 This is normally done in pci_enable_device(),
2381 so this option is a temporary workaround
2382 for broken drivers that don't call it.
2383 skip_isa_align [X86] do not align io start addr, so can
2384 handle more pci cards
2385 firmware [ARM] Do not re-enumerate the bus but instead
2386 just use the configuration from the
2387 bootloader. This is currently used on
2388 IXP2000 systems where the bus has to be
2389 configured a certain way for adjunct CPUs.
2390 noearly [X86] Don't do any early type 1 scanning.
2391 This might help on some broken boards which
2392 machine check when some devices' config space
2393 is read. But various workarounds are disabled
2394 and some IOMMU drivers will not work.
2395 bfsort Sort PCI devices into breadth-first order.
2396 This sorting is done to get a device
2397 order compatible with older (<= 2.4) kernels.
2398 nobfsort Don't sort PCI devices into breadth-first order.
2399 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
2400 tuning and use the BIOS-configured MPS defaults.
2401 pcie_bus_safe Set every device's MPS to the largest value
2402 supported by all devices below the root complex.
2403 pcie_bus_perf Set device MPS to the largest allowable MPS
2404 based on its parent bus. Also set MRRS (Max
2405 Read Request Size) to the largest supported
2406 value (no larger than the MPS that the device
2407 or bus can support) for best performance.
2408 pcie_bus_peer2peer Set every device's MPS to 128B, which
2409 every device is guaranteed to support. This
2410 configuration allows peer-to-peer DMA between
2411 any pair of devices, possibly at the cost of
2412 reduced performance. This also guarantees
2413 that hot-added devices will work.
2414 cbiosize=nn[KMG] The fixed amount of bus space which is
2415 reserved for the CardBus bridge's IO window.
2416 The default value is 256 bytes.
2417 cbmemsize=nn[KMG] The fixed amount of bus space which is
2418 reserved for the CardBus bridge's memory
2419 window. The default value is 64 megabytes.
2422 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2423 Specifies alignment and device to reassign
2424 aligned memory resources.
2425 If <order of align> is not specified,
2426 PAGE_SIZE is used as alignment.
2427 PCI-PCI bridge can be specified, if resource
2428 windows need to be expanded.
2429 ecrc= Enable/disable PCIe ECRC (transaction layer
2430 end-to-end CRC checking).
2431 bios: Use BIOS/firmware settings. This is the
2435 hpiosize=nn[KMG] The fixed amount of bus space which is
2436 reserved for hotplug bridge's IO window.
2437 Default size is 256 bytes.
2438 hpmemsize=nn[KMG] The fixed amount of bus space which is
2439 reserved for hotplug bridge's memory window.
2440 Default size is 2 megabytes.
2441 realloc= Enable/disable reallocating PCI bridge resources
2442 if allocations done by BIOS are too small to
2443 accommodate resources required by all child
2445 off: Turn realloc off
2447 realloc same as realloc=on
2448 noari do not use PCIe ARI.
2449 pcie_scan_all Scan all possible PCIe devices. Otherwise we
2450 only look for one device below a PCIe downstream
2453 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2456 force Enable ASPM even on devices that claim not to support it.
2457 WARNING: Forcing ASPM on may cause system lockups.
2459 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2460 nomsi Do not use MSI for PCI Express Native Hotplug (this
2461 makes all PCIe ports use INTx for hotplug services).
2463 pcie_ports= [PCIE] PCIe ports handling:
2464 auto Ask the BIOS whether or not to use native PCIe services
2465 associated with PCIe ports (PME, hot-plug, AER). Use
2466 them only if that is allowed by the BIOS.
2467 native Use native PCIe services associated with PCIe ports
2469 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2472 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2473 nomsi Do not use MSI for native PCIe PME signaling (this makes
2474 all PCIe root ports use INTx for all services).
2476 pcmv= [HW,PCMCIA] BadgePAD 4
2479 See Documentation/blockdev/paride.txt.
2481 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2484 See arch/parisc/kernel/pdc_chassis.c
2486 percpu_alloc= Select which percpu first chunk allocator to use.
2487 Currently supported values are "embed" and "page".
2488 Archs may support subset or none of the selections.
2489 See comments in mm/percpu.c for details on each
2490 allocator. This parameter is primarily for debugging
2491 and performance comparison.
2494 See Documentation/blockdev/paride.txt.
2497 See Documentation/blockdev/paride.txt.
2499 pirq= [SMP,APIC] Manual mp-table setup
2500 See Documentation/x86/i386/IO-APIC.txt.
2502 plip= [PPT,NET] Parallel port network link
2503 Format: { parport<nr> | timid | 0 }
2504 See also Documentation/parport.txt.
2506 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2507 Override pmtimer IOPort with a hex value.
2511 Enable PNP debug messages (depends on the
2512 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2513 via /sys/module/pnp/parameters/debug. We always show
2514 current resource usage; turning this on also shows
2515 possible settings and some assignment information.
2521 { on | off | curr | res | no-curr | no-res }
2524 [ISAPNP] Exclude IRQs for the autoconfiguration
2527 [ISAPNP] Exclude DMAs for the autoconfiguration
2529 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2530 Ranges are in pairs (I/O port base and size).
2533 [ISAPNP] Exclude memory regions for the
2535 Ranges are in pairs (memory base and size).
2537 ports= [IP_VS_FTP] IPVS ftp helper module
2539 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2541 Format: <port>,<port>....
2543 print-fatal-signals=
2544 [KNL] debug: print fatal signals
2546 If enabled, warn about various signal handling
2547 related application anomalies: too many signals,
2548 too many POSIX.1 timers, fatal signals causing a
2551 If you hit the warning due to signal overflow,
2552 you might want to try "ulimit -i unlimited".
2556 printk.always_kmsg_dump=
2557 Trigger kmsg_dump for cases other than kernel oops or
2559 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2562 printk.time= Show timing data prefixed to each printk message line
2563 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2565 processor.max_cstate= [HW,ACPI]
2566 Limit processor to maximum C-state
2567 max_cstate=9 overrides any DMI blacklist limit.
2569 processor.nocst [HW,ACPI]
2570 Ignore the _CST method to determine C-states,
2571 instead using the legacy FADT method
2573 profile= [KNL] Enable kernel profiling via /proc/profile
2574 Format: [schedule,]<number>
2575 Param: "schedule" - profile schedule points.
2576 Param: <number> - step/bucket size as a power of 2 for
2577 statistical time based profiling.
2578 Param: "sleep" - profile D-state sleeping (millisecs).
2579 Requires CONFIG_SCHEDSTATS
2580 Param: "kvm" - profile VM exits.
2582 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2584 See Documentation/blockdev/ramdisk.txt.
2586 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2587 probe for; one of (bare|imps|exps|lifebook|any).
2588 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2590 psmouse.resetafter= [HW,MOUSE]
2591 Try to reset the device after so many bad packets
2594 [HW,MOUSE] Set desired mouse resolution, in dpi.
2595 psmouse.smartscroll=
2596 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2597 0 = disabled, 1 = enabled (default).
2599 pstore.backend= Specify the name of the pstore backend to use
2602 See Documentation/blockdev/paride.txt.
2605 [KNL] Number of legacy pty's. Overwrites compiled-in
2608 quiet [KNL] Disable most log messages
2613 See Documentation/md.txt.
2615 ramdisk_blocksize= [RAM]
2616 See Documentation/blockdev/ramdisk.txt.
2618 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2619 See Documentation/blockdev/ramdisk.txt.
2622 In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2623 the specified list of CPUs to be no-callback CPUs.
2624 Invocation of these CPUs' RCU callbacks will
2625 be offloaded to "rcuox/N" kthreads created for
2626 that purpose, where "x" is "b" for RCU-bh, "p"
2627 for RCU-preempt, and "s" for RCU-sched, and "N"
2628 is the CPU number. This reduces OS jitter on the
2629 offloaded CPUs, which can be useful for HPC and
2631 real-time workloads. It can also improve energy
2632 efficiency for asymmetric multiprocessors.
2635 Rather than requiring that offloaded CPUs
2636 (specified by rcu_nocbs= above) explicitly
2637 awaken the corresponding "rcuoN" kthreads,
2638 make these kthreads poll for callbacks.
2639 This improves the real-time response for the
2640 offloaded CPUs by relieving them of the need to
2641 wake up the corresponding kthread, but degrades
2642 energy efficiency by requiring that the kthreads
2643 periodically wake up to do the polling.
2645 rcutree.blimit= [KNL]
2646 Set maximum number of finished RCU callbacks to process
2649 rcutree.rcu_fanout_leaf= [KNL]
2650 Increase the number of CPUs assigned to each
2651 leaf rcu_node structure. Useful for very large
2654 rcutree.jiffies_till_first_fqs= [KNL]
2655 Set delay from grace-period initialization to
2656 first attempt to force quiescent states.
2657 Units are jiffies, minimum value is zero,
2658 and maximum value is HZ.
2660 rcutree.jiffies_till_next_fqs= [KNL]
2661 Set delay between subsequent attempts to force
2662 quiescent states. Units are jiffies, minimum
2663 value is one, and maximum value is HZ.
2665 rcutree.qhimark= [KNL]
2666 Set threshold of queued
2667 RCU callbacks over which batch limiting is disabled.
2669 rcutree.qlowmark= [KNL]
2670 Set threshold of queued RCU callbacks below which
2671 batch limiting is re-enabled.
2673 rcutree.rcu_idle_gp_delay= [KNL]
2674 Set wakeup interval for idle CPUs that have
2675 RCU callbacks (RCU_FAST_NO_HZ=y).
2677 rcutree.rcu_idle_lazy_gp_delay= [KNL]
2678 Set wakeup interval for idle CPUs that have
2679 only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
2680 Lazy RCU callbacks are those which RCU can
2681 prove do nothing more than free memory.
2683 rcutorture.fqs_duration= [KNL]
2684 Set duration of force_quiescent_state bursts.
2686 rcutorture.fqs_holdoff= [KNL]
2687 Set holdoff time within force_quiescent_state bursts.
2689 rcutorture.fqs_stutter= [KNL]
2690 Set wait time between force_quiescent_state bursts.
2692 rcutorture.gp_exp= [KNL]
2693 Use expedited update-side primitives.
2695 rcutorture.gp_normal= [KNL]
2696 Use normal (non-expedited) update-side primitives.
2697 If both gp_exp and gp_normal are set, do both.
2698 If neither gp_exp nor gp_normal are set, still
2701 rcutorture.n_barrier_cbs= [KNL]
2702 Set callbacks/threads for rcu_barrier() testing.
2704 rcutorture.nfakewriters= [KNL]
2705 Set number of concurrent RCU writers. These just
2706 stress RCU, they don't participate in the actual
2707 test, hence the "fake".
2709 rcutorture.nreaders= [KNL]
2710 Set number of RCU readers.
2712 rcutorture.object_debug= [KNL]
2713 Enable debug-object double-call_rcu() testing.
2715 rcutorture.onoff_holdoff= [KNL]
2716 Set time (s) after boot for CPU-hotplug testing.
2718 rcutorture.onoff_interval= [KNL]
2719 Set time (s) between CPU-hotplug operations, or
2720 zero to disable CPU-hotplug testing.
2722 rcutorture.rcutorture_runnable= [BOOT]
2723 Start rcutorture running at boot time.
2725 rcutorture.shuffle_interval= [KNL]
2726 Set task-shuffle interval (s). Shuffling tasks
2727 allows some CPUs to go into dyntick-idle mode
2728 during the rcutorture test.
2730 rcutorture.shutdown_secs= [KNL]
2731 Set time (s) after boot system shutdown. This
2732 is useful for hands-off automated testing.
2734 rcutorture.stall_cpu= [KNL]
2735 Duration of CPU stall (s) to test RCU CPU stall
2736 warnings, zero to disable.
2738 rcutorture.stall_cpu_holdoff= [KNL]
2739 Time to wait (s) after boot before inducing stall.
2741 rcutorture.stat_interval= [KNL]
2742 Time (s) between statistics printk()s.
2744 rcutorture.stutter= [KNL]
2745 Time (s) to stutter testing, for example, specifying
2746 five seconds causes the test to run for five seconds,
2747 wait for five seconds, and so on. This tests RCU's
2748 ability to transition abruptly to and from idle.
2750 rcutorture.test_boost= [KNL]
2751 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
2752 "Maybe" means test if the RCU implementation
2753 under test support RCU priority boosting.
2755 rcutorture.test_boost_duration= [KNL]
2756 Duration (s) of each individual boost test.
2758 rcutorture.test_boost_interval= [KNL]
2759 Interval (s) between each boost test.
2761 rcutorture.test_no_idle_hz= [KNL]
2762 Test RCU's dyntick-idle handling. See also the
2763 rcutorture.shuffle_interval parameter.
2765 rcutorture.torture_type= [KNL]
2766 Specify the RCU implementation to test.
2768 rcutorture.verbose= [KNL]
2769 Enable additional printk() statements.
2771 rcupdate.rcu_expedited= [KNL]
2772 Use expedited grace-period primitives, for
2773 example, synchronize_rcu_expedited() instead
2774 of synchronize_rcu(). This reduces latency,
2775 but can increase CPU utilization, degrade
2776 real-time latency, and degrade energy efficiency.
2778 rcupdate.rcu_cpu_stall_suppress= [KNL]
2779 Suppress RCU CPU stall warning messages.
2781 rcupdate.rcu_cpu_stall_timeout= [KNL]
2782 Set timeout for RCU CPU stall warning messages.
2786 Run specified binary instead of /init from the ramdisk,
2787 used for early userspace startup. See initrd.
2790 Format (x86 or x86_64):
2791 [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
2793 [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
2795 Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
2796 reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
2797 reboot_force is either force or not specified,
2798 reboot_cpu is s[mp]#### with #### being the processor
2799 to be used for rebooting.
2802 [KNL, SMP] Set scheduler's default relax_domain_level.
2803 See Documentation/cgroups/cpusets.txt.
2805 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2807 reservetop= [X86-32]
2809 Reserves a hole at the top of the kernel virtual
2814 Set the amount of memory to reserve for BIOS at
2815 the bottom of the address space.
2817 reset_devices [KNL] Force drivers to reset the underlying device
2818 during initialization.
2821 Specify the partition device for software suspend
2823 {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
2825 resume_offset= [SWSUSP]
2826 Specify the offset from the beginning of the partition
2827 given by "resume=" at which the swap header is located,
2828 in <PAGE_SIZE> units (needed only for swap files).
2829 See Documentation/power/swsusp-and-swap-files.txt
2831 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2832 read the resume files
2834 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2835 Useful for devices that are detected asynchronously
2836 (e.g. USB and MMC devices).
2838 hibernate= [HIBERNATION]
2839 noresume Don't check if there's a hibernation image
2840 present during boot.
2841 nocompress Don't compress/decompress hibernation images.
2843 retain_initrd [RAM] Keep initrd memory after extraction
2845 rhash_entries= [KNL,NET]
2846 Set number of hash buckets for route cache
2848 riscom8= [HW,SERIAL]
2849 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2851 ro [KNL] Mount root device read-only on boot
2853 root= [KNL] Root filesystem
2854 See name_to_dev_t comment in init/do_mounts.c.
2856 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2857 mount the root filesystem
2859 rootflags= [KNL] Set root filesystem mount option string
2861 rootfstype= [KNL] Set root filesystem type
2863 rootwait [KNL] Wait (indefinitely) for root device to show up.
2864 Useful for devices that are detected asynchronously
2865 (e.g. USB and MMC devices).
2867 rproc_mem=nn[KMG][@address]
2868 [KNL,ARM,CMA] Remoteproc physical memory block.
2869 Memory area to be used by remote processor image,
2872 rw [KNL] Mount root device read-write on boot
2874 S [KNL] Run init in single mode
2877 See drivers/net/irda/sa1100_ir.c.
2879 sbni= [NET] Granch SBNI12 leased line adapter
2881 sched_debug [KNL] Enables verbose scheduler debug messages.
2883 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
2884 xtime_lock contention on larger systems, and/or RCU lock
2885 contention on all systems with CONFIG_MAXSMP set.
2886 Format: { "0" | "1" }
2887 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
2889 Note: increases power consumption, thus should only be
2890 enabled if running jitter sensitive (HPC/RT) workloads.
2892 security= [SECURITY] Choose a security module to enable at boot.
2893 If this boot parameter is not specified, only the first
2894 security module asking for security registration will be
2895 loaded. An invalid security module name will be treated
2896 as if no module has been chosen.
2898 selinux= [SELINUX] Disable or enable SELinux at boot time.
2899 Format: { "0" | "1" }
2900 See security/selinux/Kconfig help text.
2903 Default value is set via kernel config option.
2904 If enabled at boot time, /selinux/disable can be used
2905 later to disable prior to initial policy load.
2907 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2908 Format: { "0" | "1" }
2909 See security/apparmor/Kconfig help text
2912 Default value is set via kernel config option.
2914 serialnumber [BUGS=X86-32]
2917 Maximal number of shapers.
2919 show_msr= [x86] show boot-time MSR settings
2920 Format: { <integer> }
2921 Show boot-time (BIOS-initialized) MSR settings.
2922 The parameter means the number of CPUs to show,
2923 for example 1 means boot CPU only.
2930 slab_max_order= [MM, SLAB]
2931 Determines the maximum allowed order for slabs.
2932 A high setting may cause OOMs due to memory
2933 fragmentation. Defaults to 1 for systems with
2934 more than 32MB of RAM, 0 otherwise.
2936 slub_debug[=options[,slabs]] [MM, SLUB]
2937 Enabling slub_debug allows one to determine the
2938 culprit if slab objects become corrupted. Enabling
2939 slub_debug can create guard zones around objects and
2940 may poison objects when not in use. Also tracks the
2941 last alloc / free. For more information see
2942 Documentation/vm/slub.txt.
2944 slub_max_order= [MM, SLUB]
2945 Determines the maximum allowed order for slabs.
2946 A high setting may cause OOMs due to memory
2947 fragmentation. For more information see
2948 Documentation/vm/slub.txt.
2950 slub_min_objects= [MM, SLUB]
2951 The minimum number of objects per slab. SLUB will
2952 increase the slab order up to slub_max_order to
2953 generate a sufficiently large slab able to contain
2954 the number of objects indicated. The higher the number
2955 of objects the smaller the overhead of tracking slabs
2956 and the less frequently locks need to be acquired.
2957 For more information see Documentation/vm/slub.txt.
2959 slub_min_order= [MM, SLUB]
2960 Determines the minimum page order for slabs. Must be
2961 lower than slub_max_order.
2962 For more information see Documentation/vm/slub.txt.
2964 slub_nomerge [MM, SLUB]
2965 Disable merging of slabs with similar size. May be
2966 necessary if there is some reason to distinguish
2967 allocs to different slabs. Debug options disable
2968 merging on their own.
2969 For more information see Documentation/vm/slub.txt.
2972 Format: <io1>[,<io2>[,...,<io8>]]
2974 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2975 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2976 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2977 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2978 smsc-ircc2.ircc_irq= [HW] IRQ line
2979 smsc-ircc2.ircc_dma= [HW] DMA channel
2980 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2981 0: Toshiba Satellite 1800 (GP data pin select)
2982 1: Fast pin select (default)
2986 [KNL] Should the soft-lockup detector generate panics.
2989 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2990 See Documentation/laptops/sonypi.txt
2992 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2993 See Documentation/serial/specialix.txt.
2995 spia_io_base= [HW,MTD]
3001 Enabled the stack tracer on boot up.
3003 stacktrace_filter=[function-list]
3004 [FTRACE] Limit the functions that the stack tracer
3005 will trace at boot up. function-list is a comma separated
3006 list of functions. This list can be changed at run
3007 time by the stack_trace_filter file in the debugfs
3008 tracing directory. Note, this enables stack tracing
3009 and the stacktrace above is not needed.
3013 Set the STI (builtin display/keyboard on the HP-PARISC
3014 machines) console (graphic card) which should be used
3015 as the initial boot-console.
3016 See also comment in drivers/video/console/sticore.c.
3019 See comment in drivers/video/console/sticore.c.
3022 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
3024 sunrpc.min_resvport=
3025 sunrpc.max_resvport=
3027 SunRPC servers often require that client requests
3028 originate from a privileged port (i.e. a port in the
3029 range 0 < portnr < 1024).
3030 An administrator who wishes to reserve some of these
3031 ports for other uses may adjust the range that the
3032 kernel's sunrpc client considers to be privileged
3033 using these two parameters to set the minimum and
3034 maximum port values.
3038 Control how the NFS server code allocates CPUs to
3039 service thread pools. Depending on how many NICs
3040 you have and where their interrupts are bound, this
3041 option will affect which CPUs will do NFS serving.
3042 Note: this parameter cannot be changed while the
3043 NFS server is running.
3045 auto the server chooses an appropriate mode
3046 automatically using heuristics
3047 global a single global pool contains all CPUs
3048 percpu one pool for each CPU
3049 pernode one pool for each NUMA node (equivalent
3050 to global on non-NUMA machines)
3052 sunrpc.tcp_slot_table_entries=
3053 sunrpc.udp_slot_table_entries=
3055 Sets the upper limit on the number of simultaneous
3056 RPC calls that can be sent from the client to a
3057 server. Increasing these values may allow you to
3058 improve throughput, but will also increase the
3059 amount of memory reserved for use by the client.
3062 [KNL] Enable accounting of swap in memory resource
3063 controller if no parameter or 1 is given or disable
3064 it if 0 is given (See Documentation/cgroups/memory.txt)
3066 swiotlb= [IA-64] Number of I/O TLB slabs
3070 sysfs.deprecated=0|1 [KNL]
3071 Enable/disable old style sysfs layout for old udev
3072 on older distributions. When this option is enabled
3073 very new udev will not work anymore. When this option
3074 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
3075 in older udev will not work anymore.
3076 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
3077 the kernel configuration.
3079 sysrq_always_enabled
3081 Ignore sysrq setting - this boot parameter will
3082 neutralize any effect of /proc/sys/kernel/sysrq.
3083 Useful for debugging.
3087 test_suspend= [SUSPEND]
3088 Specify "mem" (for Suspend-to-RAM) or "standby" (for
3089 standby suspend) as the system sleep state to briefly
3090 enter during system startup. The system is woken from
3091 this state using a wakeup-capable RTC alarm.
3093 thash_entries= [KNL,NET]
3094 Set number of hash buckets for TCP connection
3096 thermal.act= [HW,ACPI]
3097 -1: disable all active trip points in all thermal zones
3098 <degrees C>: override all lowest active trip points
3100 thermal.crt= [HW,ACPI]
3101 -1: disable all critical trip points in all thermal zones
3102 <degrees C>: override all critical trip points
3104 thermal.nocrt= [HW,ACPI]
3105 Set to disable actions on ACPI thermal zone
3106 critical and hot trip points.
3108 thermal.off= [HW,ACPI]
3109 1: disable ACPI thermal control
3111 thermal.psv= [HW,ACPI]
3112 -1: disable all passive trip points
3113 <degrees C>: override all passive trip points to this
3116 thermal.tzp= [HW,ACPI]
3117 Specify global default ACPI thermal zone polling rate
3118 <deci-seconds>: poll all this frequency
3119 0: no polling (default)
3122 Force threading of all interrupt handlers except those
3123 marked explicitly IRQF_NO_THREAD.
3126 Enable the Transcendent memory driver if built-in.
3128 tmem.cleancache=0|1 [KNL, XEN]
3129 Default is on (1). Disable the usage of the cleancache
3130 API to send anonymous pages to the hypervisor.
3132 tmem.frontswap=0|1 [KNL, XEN]
3133 Default is on (1). Disable the usage of the frontswap
3134 API to send swap pages to the hypervisor. If disabled
3135 the selfballooning and selfshrinking are force disabled.
3137 tmem.selfballooning=0|1 [KNL, XEN]
3138 Default is on (1). Disable the driving of swap pages
3141 tmem.selfshrinking=0|1 [KNL, XEN]
3142 Default is on (1). Partial swapoff that immediately
3143 transfers pages from Xen hypervisor back to the
3144 kernel based on different criteria.
3148 Specify if the kernel should make use of the cpu
3149 topology information if the hardware supports this.
3150 The scheduler will make use of this information and
3151 e.g. base its process migration decisions on it.
3156 tpm_suspend_pcr=[HW,TPM]
3157 Format: integer pcr id
3158 Specify that at suspend time, the tpm driver
3159 should extend the specified pcr with zeros,
3160 as a workaround for some chips which fail to
3161 flush the last written pcr on TPM_SaveState.
3162 This will guarantee that all the other pcrs
3165 trace_buf_size=nn[KMG]
3166 [FTRACE] will set tracing buffer size.
3168 trace_event=[event-list]
3169 [FTRACE] Set and start specified trace events in order
3170 to facilitate early boot debugging.
3171 See also Documentation/trace/events.txt
3173 trace_options=[option-list]
3174 [FTRACE] Enable or disable tracer options at boot.
3175 The option-list is a comma delimited list of options
3176 that can be enabled or disabled just as if you were
3177 to echo the option name into
3179 /sys/kernel/debug/tracing/trace_options
3181 For example, to enable stacktrace option (to dump the
3182 stack trace of each event), add to the command line:
3184 trace_options=stacktrace
3186 See also Documentation/trace/ftrace.txt "trace options"
3190 [FTRACE] enable this option to disable tracing when a
3191 warning is hit. This turns off "tracing_on". Tracing can
3192 be enabled again by echoing '1' into the "tracing_on"
3193 file located in /sys/kernel/debug/tracing/
3195 This option is useful, as it disables the trace before
3196 the WARNING dump is called, which prevents the trace to
3197 be filled with content caused by the warning output.
3199 This option can also be set at run time via the sysctl
3200 option: kernel/traceoff_on_warning
3202 transparent_hugepage=
3204 Format: [always|madvise|never]
3205 Can be used to control the default behavior of the system
3206 with respect to transparent hugepages.
3207 See Documentation/vm/transhuge.txt for more details.
3209 tsc= Disable clocksource stability checks for TSC.
3211 [x86] reliable: mark tsc clocksource as reliable, this
3212 disables clocksource verification at runtime, as well
3213 as the stability checks done at bootup. Used to enable
3214 high-resolution timer mode on older hardware, and in
3215 virtualized environment.
3216 [x86] noirqtime: Do not use TSC to do irq accounting.
3217 Used to run time disable IRQ_TIME_ACCOUNTING on any
3218 platforms where RDTSC is slow and this accounting
3221 turbografx.map[2|3]= [HW,JOY]
3222 TurboGraFX parallel port interface
3224 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
3225 See also Documentation/input/joystick-parport.txt
3227 udbg-immortal [PPC] When debugging early kernel crashes that
3228 happen after console_init() and before a proper
3229 console driver takes over, this boot options might
3230 help "seeing" what's going on.
3232 uhash_entries= [KNL,NET]
3233 Set number of hash buckets for UDP/UDP-Lite connections
3236 [USB] Ignore overcurrent events (default N).
3237 Some badly-designed motherboards generate lots of
3238 bogus events, for ports that aren't wired to
3239 anything. Set this parameter to avoid log spamming.
3240 Note that genuine overcurrent events won't be
3244 [X86] Cause panic on unknown NMI.
3246 usbcore.authorized_default=
3247 [USB] Default USB device authorization:
3248 (default -1 = authorized except for wireless USB,
3249 0 = not authorized, 1 = authorized)
3251 usbcore.autosuspend=
3252 [USB] The autosuspend time delay (in seconds) used
3253 for newly-detected USB devices (default 2). This
3254 is the time required before an idle device will be
3255 autosuspended. Devices for which the delay is set
3256 to a negative value won't be autosuspended at all.
3258 usbcore.usbfs_snoop=
3259 [USB] Set to log all usbfs traffic (default 0 = off).
3261 usbcore.blinkenlights=
3262 [USB] Set to cycle leds on hubs (default 0 = off).
3264 usbcore.old_scheme_first=
3265 [USB] Start with the old device initialization
3266 scheme (default 0 = off).
3268 usbcore.usbfs_memory_mb=
3269 [USB] Memory limit (in MB) for buffers allocated by
3270 usbfs (default = 16, 0 = max = 2047).
3272 usbcore.use_both_schemes=
3273 [USB] Try the other device initialization scheme
3274 if the first one fails (default 1 = enabled).
3276 usbcore.initial_descriptor_timeout=
3277 [USB] Specifies timeout for the initial 64-byte
3278 USB_REQ_GET_DESCRIPTOR request in milliseconds
3279 (default 5000 = 5.0 seconds).
3282 [USBHID] The interval which mice are to be polled at.
3284 usb-storage.delay_use=
3285 [UMS] The delay in seconds before a new device is
3286 scanned for Logical Units (default 5).
3289 [UMS] A list of quirks entries to supplement or
3290 override the built-in unusual_devs list. List
3291 entries are separated by commas. Each entry has
3292 the form VID:PID:Flags where VID and PID are Vendor
3293 and Product ID values (4-digit hex numbers) and
3294 Flags is a set of characters, each corresponding
3295 to a common usb-storage quirk flag as follows:
3296 a = SANE_SENSE (collect more than 18 bytes
3298 b = BAD_SENSE (don't collect more than 18
3299 bytes of sense data);
3300 c = FIX_CAPACITY (decrease the reported
3301 device capacity by one sector);
3302 d = NO_READ_DISC_INFO (don't use
3303 READ_DISC_INFO command);
3304 e = NO_READ_CAPACITY_16 (don't use
3305 READ_CAPACITY_16 command);
3306 h = CAPACITY_HEURISTICS (decrease the
3307 reported device capacity by one
3308 sector if the number is odd);
3309 i = IGNORE_DEVICE (don't bind to this
3311 l = NOT_LOCKABLE (don't try to lock and
3312 unlock ejectable media);
3313 m = MAX_SECTORS_64 (don't transfer more
3314 than 64 sectors = 32 KB at a time);
3315 n = INITIAL_READ10 (force a retry of the
3316 initial READ(10) command);
3317 o = CAPACITY_OK (accept the capacity
3318 reported by the device);
3319 p = WRITE_CACHE (the device cache is ON
3321 r = IGNORE_RESIDUE (the device reports
3322 bogus residue values);
3323 s = SINGLE_LUN (the device has only one
3325 w = NO_WP_DETECT (don't test whether the
3326 medium is write-protected).
3327 Example: quirks=0419:aaf5:rl,0421:0433:rc
3329 user_debug= [KNL,ARM]
3331 See arch/arm/Kconfig.debug help text.
3332 1 - undefined instruction events
3334 4 - invalid data aborts
3337 Example: user_debug=31
3340 [X86] Flags controlling user PTE allocations.
3342 nohigh = do not allocate PTE pages in
3343 HIGHMEM regardless of setting
3347 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
3348 vdso=1: enable VDSO (default)
3349 vdso=0: disable VDSO mapping
3352 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
3353 vdso32=1: enable 32-bit VDSO (default)
3354 vdso32=0: disable 32-bit VDSO mapping
3357 vector=percpu: enable percpu vector domain
3359 video= [FB] Frame buffer configuration
3360 See Documentation/fb/modedb.txt.
3362 video.brightness_switch_enabled= [0,1]
3363 If set to 1, on receiving an ACPI notify event
3364 generated by hotkey, video driver will adjust brightness
3365 level and then send out the event to user space through
3366 the allocated input device; If set to 0, video driver
3367 will only send out the event without touching backlight
3372 [VMMIO] Memory mapped virtio (platform) device.
3374 <size>@<baseaddr>:<irq>[:<id>]
3376 <size> := size (can use standard suffixes
3378 <baseaddr> := physical base address
3379 <irq> := interrupt number (as passed to
3381 <id> := (optional) platform device id
3383 virtio_mmio.device=1K@0x100b0000:48:7
3385 Can be used multiple times for multiple devices.
3387 vga= [BOOT,X86-32] Select a particular video mode
3388 See Documentation/x86/boot.txt and
3389 Documentation/svga.txt.
3390 Use vga=ask for menu.
3391 This is actually a boot loader parameter; the value is
3392 passed to the kernel using a special protocol.
3394 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
3395 size of <nn>. This can be used to increase the
3396 minimum size (128MB on x86). It can also be used to
3397 decrease the size and leave more room for directly
3400 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
3403 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
3406 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
3410 Controls the behavior of vsyscalls (i.e. calls to
3411 fixed addresses of 0xffffffffff600x00 from legacy
3412 code). Most statically-linked binaries and older
3413 versions of glibc use these calls. Because these
3414 functions are at fixed addresses, they make nice
3415 targets for exploits that can control RIP.
3417 emulate [default] Vsyscalls turn into traps and are
3418 emulated reasonably safely.
3420 native Vsyscalls are native syscall instructions.
3421 This is a little bit faster than trapping
3422 and makes a few dynamic recompilers work
3423 better than they would in emulation mode.
3424 It also makes exploits much easier to write.
3426 none Vsyscalls don't work at all. This makes
3427 them quite hard to use for exploits but
3428 might break your system.
3430 vt.color= [VT] Default text color.
3431 Format: 0xYX, X = foreground, Y = background.
3432 Default: 0x07 = light gray on black.
3434 vt.cur_default= [VT] Default cursor shape.
3435 Format: 0xCCBBAA, where AA, BB, and CC are the same as
3436 the parameters of the <Esc>[?A;B;Cc escape sequence;
3437 see VGA-softcursor.txt. Default: 2 = underline.
3439 vt.default_blu= [VT]
3440 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3441 Change the default blue palette of the console.
3442 This is a 16-member array composed of values
3445 vt.default_grn= [VT]
3446 Format: <green0>,<green1>,<green2>,...,<green15>
3447 Change the default green palette of the console.
3448 This is a 16-member array composed of values
3451 vt.default_red= [VT]
3452 Format: <red0>,<red1>,<red2>,...,<red15>
3453 Change the default red palette of the console.
3454 This is a 16-member array composed of values
3460 Set system-wide default UTF-8 mode for all tty's.
3461 Default is 1, i.e. UTF-8 mode is enabled for all
3462 newly opened terminals.
3464 vt.global_cursor_default=
3467 Set system-wide default for whether a cursor
3468 is shown on new VTs. Default is -1,
3469 i.e. cursors will be created by default unless
3470 overridden by individual drivers. 0 will hide
3471 cursors, 1 will display them.
3473 vt.italic= [VT] Default color for italic text; 0-15.
3476 vt.underline= [VT] Default color for underlined text; 0-15.
3479 watchdog timers [HW,WDT] For information on watchdog timers,
3480 see Documentation/watchdog/watchdog-parameters.txt
3481 or other driver-specific files in the
3482 Documentation/watchdog/ directory.
3484 workqueue.disable_numa
3485 By default, all work items queued to unbound
3486 workqueues are affine to the NUMA nodes they're
3487 issued on, which results in better behavior in
3488 general. If NUMA affinity needs to be disabled for
3489 whatever reason, this option can be used. Note
3490 that this also can be controlled per-workqueue for
3491 workqueues visible under /sys/bus/workqueue/.
3493 workqueue.power_efficient
3494 Per-cpu workqueues are generally preferred because
3495 they show better performance thanks to cache
3496 locality; unfortunately, per-cpu workqueues tend to
3497 be more power hungry than unbound workqueues.
3499 Enabling this makes the per-cpu workqueues which
3500 were observed to contribute significantly to power
3501 consumption unbound, leading to measurably lower
3502 power usage at the cost of small performance
3505 The default value of this parameter is determined by
3506 the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
3508 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
3509 default x2apic cluster mode on platforms
3512 x86_intel_mid_timer= [X86-32,APBT]
3513 Choose timer option for x86 Intel MID platform.
3514 Two valid options are apbt timer only and lapic timer
3515 plus one apbt timer for broadcast timer.
3516 x86_intel_mid_timer=apbt_only | lapic_and_apbt
3518 xen_emul_unplug= [HW,X86,XEN]
3519 Unplug Xen emulated devices
3520 Format: [unplug0,][unplug1]
3521 ide-disks -- unplug primary master IDE devices
3522 aux-ide-disks -- unplug non-primary-master IDE devices
3523 nics -- unplug network devices
3524 all -- unplug all emulated devices (NICs and IDE disks)
3525 unnecessary -- unplugging emulated devices is
3526 unnecessary even if the host did not respond to
3528 never -- do not unplug even if version check succeeds
3530 xen_nopvspin [X86,XEN]
3531 Disables the ticketlock slowpath using Xen PV
3534 xirc2ps_cs= [NET,PCMCIA]
3536 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
3538 ______________________________________________________________________
3542 Add more DRM drivers.
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blob