4 The following is a consolidated list of the kernel parameters as
5 implemented by the __setup(), core_param() and module_param() macros
6 and sorted into English Dictionary order (defined as ignoring all
7 punctuation and sorting digits before letters in a case insensitive
8 manner), and with descriptions where known.
10 The kernel parses parameters from the kernel command line up to "--";
11 if it doesn't recognize a parameter and it doesn't contain a '.', the
12 parameter gets passed to init: parameters with '=' go into init's
13 environment, others are passed as command line arguments to init.
14 Everything after "--" is passed as an argument to init.
16 Module parameters can be specified in two ways: via the kernel command
17 line with a module name prefix, or via modprobe, e.g.:
19 (kernel command line) usbcore.blinkenlights=1
20 (modprobe command line) modprobe usbcore blinkenlights=1
22 Parameters for modules which are built into the kernel need to be
23 specified on the kernel command line. modprobe looks through the
24 kernel command line (/proc/cmdline) and collects module parameters
25 when it loads a module, so the kernel command line can be used for
28 Hyphens (dashes) and underscores are equivalent in parameter names, so
29 log_buf_len=1M print-fatal-signals=1
30 can also be entered as
31 log-buf-len=1M print_fatal_signals=1
33 Double-quotes can be used to protect spaces in values, e.g.:
34 param="spaces in here"
36 This document may not be entirely up to date and comprehensive. The command
37 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
38 module. Loadable modules, after being loaded into the running kernel, also
39 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
40 parameters may be changed at runtime by the command
41 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
43 The parameters listed below are only valid if certain kernel build options were
44 enabled and if respective hardware is present. The text in square brackets at
45 the beginning of each description states the restrictions within which a
46 parameter is applicable:
48 ACPI ACPI support is enabled.
49 AGP AGP (Accelerated Graphics Port) is enabled.
50 ALSA ALSA sound support is enabled.
51 APIC APIC support is enabled.
52 APM Advanced Power Management support is enabled.
53 ARM ARM architecture is enabled.
54 AVR32 AVR32 architecture is enabled.
55 AX25 Appropriate AX.25 support is enabled.
56 BLACKFIN Blackfin architecture is enabled.
57 CLK Common clock infrastructure is enabled.
58 CMA Contiguous Memory Area support is enabled.
59 DRM Direct Rendering Management support is enabled.
60 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
61 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
62 EFI EFI Partitioning (GPT) is enabled
63 EIDE EIDE/ATAPI support is enabled.
64 EVM Extended Verification Module
65 FB The frame buffer device is enabled.
66 FTRACE Function tracing enabled.
67 GCOV GCOV profiling is enabled.
68 HW Appropriate hardware is enabled.
69 IA-64 IA-64 architecture is enabled.
70 IMA Integrity measurement architecture is enabled.
71 IOSCHED More than one I/O scheduler is enabled.
72 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
73 IPV6 IPv6 support is enabled.
74 ISAPNP ISA PnP code is enabled.
75 ISDN Appropriate ISDN support is enabled.
76 JOY Appropriate joystick support is enabled.
77 KGDB Kernel debugger support is enabled.
78 KVM Kernel Virtual Machine support is enabled.
79 LIBATA Libata driver is enabled
80 LP Printer support is enabled.
81 LOOP Loopback device support is enabled.
82 M68k M68k architecture is enabled.
83 These options have more detailed description inside of
84 Documentation/m68k/kernel-options.txt.
85 MDA MDA console support is enabled.
86 MIPS MIPS architecture is enabled.
87 MOUSE Appropriate mouse support is enabled.
88 MSI Message Signaled Interrupts (PCI).
89 MTD MTD (Memory Technology Device) support is enabled.
90 NET Appropriate network support is enabled.
91 NUMA NUMA support is enabled.
92 NFS Appropriate NFS support is enabled.
93 OSS OSS sound support is enabled.
94 PV_OPS A paravirtualized kernel is enabled.
95 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
96 PARISC The PA-RISC architecture is enabled.
97 PCI PCI bus support is enabled.
98 PCIE PCI Express support is enabled.
99 PCMCIA The PCMCIA subsystem is enabled.
100 PNP Plug & Play support is enabled.
101 PPC PowerPC architecture is enabled.
102 PPT Parallel port support is enabled.
103 PS2 Appropriate PS/2 support is enabled.
104 RAM RAM disk support is enabled.
105 S390 S390 architecture is enabled.
106 SCSI Appropriate SCSI support is enabled.
107 A lot of drivers have their options described inside
108 the Documentation/scsi/ sub-directory.
109 SECURITY Different security models are enabled.
110 SELINUX SELinux support is enabled.
111 APPARMOR AppArmor support is enabled.
112 SERIAL Serial support is enabled.
113 SH SuperH architecture is enabled.
114 SMP The kernel is an SMP kernel.
115 SPARC Sparc architecture is enabled.
116 SWSUSP Software suspend (hibernation) is enabled.
117 SUSPEND System suspend states are enabled.
118 TPM TPM drivers are enabled.
119 TS Appropriate touchscreen support is enabled.
120 UMS USB Mass Storage support is enabled.
121 USB USB support is enabled.
122 USBHID USB Human Interface Device support is enabled.
123 V4L Video For Linux support is enabled.
124 VMMIO Driver for memory mapped virtio devices is enabled.
125 VGA The VGA console has been enabled.
126 VT Virtual terminal support is enabled.
127 WDT Watchdog support is enabled.
128 XT IBM PC/XT MFM hard disk support is enabled.
129 X86-32 X86-32, aka i386 architecture is enabled.
130 X86-64 X86-64 architecture is enabled.
131 More X86-64 boot options can be found in
132 Documentation/x86/x86_64/boot-options.txt .
133 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
134 XEN Xen support is enabled
136 In addition, the following text indicates that the option:
138 BUGS= Relates to possible processor bugs on the said processor.
139 KNL Is a kernel start-up parameter.
140 BOOT Is a boot loader parameter.
142 Parameters denoted with BOOT are actually interpreted by the boot
143 loader, and have no meaning to the kernel directly.
144 Do not modify the syntax of boot loader parameters without extreme
145 need or coordination with <Documentation/x86/boot.txt>.
147 There are also arch-specific kernel-parameters not documented here.
148 See for example <Documentation/x86/x86_64/boot-options.txt>.
150 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
151 a trailing = on the name of any parameter states that that parameter will
152 be entered as an environment variable, whereas its absence indicates that
153 it will appear as a kernel argument readable via /proc/cmdline by programs
154 running once the system is up.
156 The number of kernel parameters is not limited, but the length of the
157 complete command line (parameters including spaces etc.) is limited to
158 a fixed number of characters. This limit depends on the architecture
159 and is between 256 and 4096 characters. It is defined in the file
160 ./include/asm/setup.h as COMMAND_LINE_SIZE.
162 Finally, the [KMG] suffix is commonly described after a number of kernel
163 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
164 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
165 bytes respectively. Such letter suffixes can also be entirely omitted.
168 acpi= [HW,ACPI,X86,ARM64]
169 Advanced Configuration and Power Interface
170 Format: { force | off | strict | noirq | rsdt }
171 force -- enable ACPI if default was off
172 off -- disable ACPI if default was on
173 noirq -- do not use ACPI for IRQ routing
174 strict -- Be less tolerant of platforms that are not
175 strictly ACPI specification compliant.
176 rsdt -- prefer RSDT over (default) XSDT
177 copy_dsdt -- copy DSDT to memory
178 For ARM64, ONLY "acpi=off" or "acpi=force" are available
180 See also Documentation/power/runtime_pm.txt, pci=noacpi
182 acpi_apic_instance= [ACPI, IOAPIC]
184 2: use 2nd APIC table, if available
185 1,0: use 1st APIC table
188 acpi_backlight= [HW,ACPI]
189 acpi_backlight=vendor
191 If set to vendor, prefer vendor specific driver
192 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
193 of the ACPI video.ko driver.
195 acpica_no_return_repair [HW, ACPI]
196 Disable AML predefined validation mechanism
197 This mechanism can repair the evaluation result to make
198 the return objects more ACPI specification compliant.
199 This option is useful for developers to identify the
200 root cause of an AML interpreter issue when the issue
201 has something to do with the repair mechanism.
203 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
204 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
206 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
207 debug output. Bits in debug_layer correspond to a
208 _COMPONENT in an ACPI source file, e.g.,
209 #define _COMPONENT ACPI_PCI_COMPONENT
210 Bits in debug_level correspond to a level in
211 ACPI_DEBUG_PRINT statements, e.g.,
212 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
213 The debug_level mask defaults to "info". See
214 Documentation/acpi/debug.txt for more information about
215 debug layers and levels.
217 Enable processor driver info messages:
218 acpi.debug_layer=0x20000000
219 Enable PCI/PCI interrupt routing info messages:
220 acpi.debug_layer=0x400000
221 Enable AML "Debug" output, i.e., stores to the Debug
222 object while interpreting AML:
223 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
224 Enable all messages related to ACPI hardware:
225 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
227 Some values produce so much output that the system is
228 unusable. The "log_buf_len" parameter may be useful
229 if you need to capture more output.
231 acpi_enforce_resources= [ACPI]
232 { strict | lax | no }
233 Check for resource conflicts between native drivers
234 and ACPI OperationRegions (SystemIO and SystemMemory
235 only). IO ports and memory declared in ACPI might be
236 used by the ACPI subsystem in arbitrary AML code and
237 can interfere with legacy drivers.
238 strict (default): access to resources claimed by ACPI
239 is denied; legacy drivers trying to access reserved
240 resources will fail to bind to device using them.
241 lax: access to resources claimed by ACPI is allowed;
242 legacy drivers trying to access reserved resources
243 will bind successfully but a warning message is logged.
244 no: ACPI OperationRegions are not marked as reserved,
245 no further checks are performed.
247 acpi_force_table_verification [HW,ACPI]
248 Enable table checksum verification during early stage.
249 By default, this is disabled due to x86 early mapping
252 acpi_irq_balance [HW,ACPI]
253 ACPI will balance active IRQs
256 acpi_irq_nobalance [HW,ACPI]
257 ACPI will not move active IRQs (default)
260 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
261 Format: <irq>,<irq>...
263 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
265 Format: <irq>,<irq>...
267 acpi_no_auto_serialize [HW,ACPI]
268 Disable auto-serialization of AML methods
269 AML control methods that contain the opcodes to create
270 named objects will be marked as "Serialized" by the
271 auto-serialization feature.
272 This feature is enabled by default.
273 This option allows to turn off the feature.
275 acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
278 acpi_no_static_ssdt [HW,ACPI]
279 Disable installation of static SSDTs at early boot time
280 By default, SSDTs contained in the RSDT/XSDT will be
281 installed automatically and they will appear under
282 /sys/firmware/acpi/tables.
283 This option turns off this feature.
284 Note that specifying this option does not affect
285 dynamic table installation which will install SSDT
286 tables to /sys/firmware/acpi/tables/dynamic.
288 acpi_rsdp= [ACPI,EFI,KEXEC]
289 Pass the RSDP address to the kernel, mostly used
290 on machines running EFI runtime service to boot the
291 second kernel for kdump.
293 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
294 Format: To spoof as Windows 98: ="Microsoft Windows"
296 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
297 acpi_osi="string1" # add string1
298 acpi_osi="!string2" # remove string2
299 acpi_osi=!* # remove all strings
300 acpi_osi=! # disable all built-in OS vendor
302 acpi_osi= # disable all strings
304 'acpi_osi=!' can be used in combination with single or
305 multiple 'acpi_osi="string1"' to support specific OS
306 vendor string(s). Note that such command can only
307 affect the default state of the OS vendor strings, thus
308 it cannot affect the default state of the feature group
309 strings and the current state of the OS vendor strings,
310 specifying it multiple times through kernel command line
311 is meaningless. This command is useful when one do not
312 care about the state of the feature group strings which
313 should be controlled by the OSPM.
315 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
316 to 'acpi_osi="Windows 2000" acpi_osi=!', they all
317 can make '_OSI("Windows 2000")' TRUE.
319 'acpi_osi=' cannot be used in combination with other
320 'acpi_osi=' command lines, the _OSI method will not
321 exist in the ACPI namespace. NOTE that such command can
322 only affect the _OSI support state, thus specifying it
323 multiple times through kernel command line is also
326 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
329 'acpi_osi=!*' can be used in combination with single or
330 multiple 'acpi_osi="string1"' to support specific
331 string(s). Note that such command can affect the
332 current state of both the OS vendor strings and the
333 feature group strings, thus specifying it multiple times
334 through kernel command line is meaningful. But it may
335 still not able to affect the final state of a string if
336 there are quirks related to this string. This command
337 is useful when one want to control the state of the
338 feature group strings to debug BIOS issues related to
341 1. 'acpi_osi="Module Device" acpi_osi=!*' can make
342 '_OSI("Module Device")' FALSE.
343 2. 'acpi_osi=!* acpi_osi="Module Device"' can make
344 '_OSI("Module Device")' TRUE.
345 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
347 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
349 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
350 they all will make '_OSI("Windows 2000")' TRUE.
353 Override the pmtimer bug detection: force the kernel
354 to assume that this machine's pmtimer latches its value
355 and always returns good values.
357 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
358 Format: { level | edge | high | low }
360 acpi_skip_timer_override [HW,ACPI]
361 Recognize and ignore IRQ0/pin2 Interrupt Override.
362 For broken nForce2 BIOS resulting in XT-PIC timer.
364 acpi_sleep= [HW,ACPI] Sleep options
365 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
366 old_ordering, nonvs, sci_force_enable }
367 See Documentation/power/video.txt for information on
369 s3_beep is for debugging; it makes the PC's speaker beep
370 as soon as the kernel's real-mode entry point is called.
371 s4_nohwsig prevents ACPI hardware signature from being
372 used during resume from hibernation.
373 old_ordering causes the ACPI 1.0 ordering of the _PTS
374 control method, with respect to putting devices into
375 low power states, to be enforced (the ACPI 2.0 ordering
376 of _PTS is used by default).
377 nonvs prevents the kernel from saving/restoring the
378 ACPI NVS memory during suspend/hibernation and resume.
379 sci_force_enable causes the kernel to set SCI_EN directly
380 on resume from S1/S3 (which is against the ACPI spec,
381 but some broken systems don't work without it).
383 acpi_use_timer_override [HW,ACPI]
384 Use timer override. For some broken Nvidia NF5 boards
385 that require a timer override, but don't have HPET
387 add_efi_memmap [EFI; X86] Include EFI memory map in
388 kernel's map of available physical RAM.
391 { off | try_unsupported }
392 off: disable AGP support
393 try_unsupported: try to drive unsupported chipsets
394 (may crash computer or cause data corruption)
397 See Documentation/sound/alsa/alsa-parameters.txt
400 Allow the default userspace alignment fault handler
401 behaviour to be specified. Bit 0 enables warnings,
402 bit 1 enables fixups, and bit 2 sends a segfault.
404 align_va_addr= [X86-64]
405 Align virtual addresses by clearing slice [14:12] when
406 allocating a VMA at process creation time. This option
407 gives you up to 3% performance improvement on AMD F15h
408 machines (where it is enabled by default) for a
409 CPU-intensive style benchmark, and it can vary highly in
410 a microbenchmark depending on workload and compiler.
412 32: only for 32-bit processes
413 64: only for 64-bit processes
414 on: enable for both 32- and 64-bit processes
415 off: disable for both 32- and 64-bit processes
417 alloc_snapshot [FTRACE]
418 Allocate the ftrace snapshot buffer on boot up when the
419 main buffer is allocated. This is handy if debugging
420 and you need to use tracing_snapshot() on boot up, and
421 do not want to use tracing_snapshot_alloc() as it needs
422 to be done where GFP_KERNEL allocations are allowed.
424 amd_iommu= [HW,X86-64]
425 Pass parameters to the AMD IOMMU driver in the system.
427 fullflush - enable flushing of IO/TLB entries when
428 they are unmapped. Otherwise they are
429 flushed before they will be reused, which
431 off - do not initialize any AMD IOMMU found in
433 force_isolation - Force device isolation for all
434 devices. The IOMMU driver is not
435 allowed anymore to lift isolation
436 requirements as needed. This option
437 does not override iommu=pt
439 amd_iommu_dump= [HW,X86-64]
440 Enable AMD IOMMU driver option to dump the ACPI table
441 for AMD IOMMU. With this option enabled, AMD IOMMU
442 driver will print ACPI tables for AMD IOMMU during
443 IOMMU initialization.
445 amijoy.map= [HW,JOY] Amiga joystick support
446 Map of devices attached to JOY0DAT and JOY1DAT
448 See also Documentation/input/joystick.txt
450 analog.map= [HW,JOY] Analog joystick and gamepad support
451 Specifies type or capabilities of an analog joystick
452 connected to one of 16 gameports
453 Format: <type1>,<type2>,..<type16>
456 Power management functions (SPARCstation-4/5 + deriv.)
458 Disable APC CPU standby support. SPARCstation-Fox does
459 not play well with APC CPU idle - disable it if you have
460 APC and your system crashes randomly.
462 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
463 Change the output verbosity whilst booting
464 Format: { quiet (default) | verbose | debug }
465 Change the amount of debugging information output
466 when initialising the APIC and IO-APIC components.
469 See Documentation/networking/ipv6.txt.
471 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
472 Limit apic dumping. The parameter defines the maximal
473 number of local apics being dumped. Also it is possible
474 to set it to "all" by meaning -- no limit here.
475 Format: { 1 (default) | 2 | ... | all }.
476 The parameter valid if only apic=debug or
477 apic=verbose is specified.
478 Example: apic=debug show_lapic=all
480 apm= [APM] Advanced Power Management
481 See header of arch/x86/kernel/apm_32.c.
483 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
484 Format: <io>,<irq>,<nodeID>
488 atarimouse= [HW,MOUSE] Atari Mouse
490 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
491 EzKey and similar keyboards
493 atkbd.reset= [HW] Reset keyboard during initialization
495 atkbd.set= [HW] Select keyboard code set
496 Format: <int> (2 = AT (default), 3 = PS/2)
498 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
501 atkbd.softraw= [HW] Choose between synthetic and real raw mode
502 Format: <bool> (0 = real, 1 = synthetic (default))
504 atkbd.softrepeat= [HW]
505 Use software keyboard repeat
507 audit= [KNL] Enable the audit sub-system
508 Format: { "0" | "1" } (0 = disabled, 1 = enabled)
509 0 - kernel audit is disabled and can not be enabled
510 until the next reboot
511 unset - kernel audit is initialized but disabled and
512 will be fully enabled by the userspace auditd.
513 1 - kernel audit is initialized and partially enabled,
514 storing at most audit_backlog_limit messages in
515 RAM until it is fully enabled by the userspace
519 audit_backlog_limit= [KNL] Set the audit queue size limit.
520 Format: <int> (must be >=0)
523 baycom_epp= [HW,AX25]
526 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
528 See header of drivers/net/hamradio/baycom_par.c.
530 baycom_ser_fdx= [HW,AX25]
531 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
532 Format: <io>,<irq>,<mode>[,<baud>]
533 See header of drivers/net/hamradio/baycom_ser_fdx.c.
535 baycom_ser_hdx= [HW,AX25]
536 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
537 Format: <io>,<irq>,<mode>
538 See header of drivers/net/hamradio/baycom_ser_hdx.c.
540 blkdevparts= Manual partition parsing of block device(s) for
541 embedded devices based on command line input.
542 See Documentation/block/cmdline-partition.txt
544 boot_delay= Milliseconds to delay each printk during boot.
545 Values larger than 10 seconds (10000) are changed to
549 bootmem_debug [KNL] Enable bootmem allocator debug messages.
551 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
552 bttv.radio= Most important insmod options are available as
554 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
557 bulk_remove=off [PPC] This parameter disables the use of the pSeries
558 firmware feature for flushing multiple hpte entries
561 c101= [NET] Moxa C101 synchronous serial card
563 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
564 Sometimes CPU hardware bugs make them report the cache
565 size incorrectly. The kernel will attempt work arounds
566 to fix known problems, but for some CPUs it is not
567 possible to determine what the correct size should be.
568 This option provides an override for these situations.
570 ca_keys= [KEYS] This parameter identifies a specific key(s) on
571 the system trusted keyring to be used for certificate
573 format: { id:<keyid> | builtin }
575 cca= [MIPS] Override the kernel pages' cache coherency
576 algorithm. Accepted values range from 0 to 7
577 inclusive. See arch/mips/include/asm/pgtable-bits.h
578 for platform specific values (SB1, Loongson3 and
581 ccw_timeout_log [S390]
582 See Documentation/s390/CommonIO for details.
584 cgroup_disable= [KNL] Disable a particular controller
585 Format: {name of the controller(s) to disable}
586 The effects of cgroup_disable=foo are:
587 - foo isn't auto-mounted if you mount all cgroups in
589 - foo isn't visible as an individually mountable
591 {Currently only "memory" controller deal with this and
592 cut the overhead, others just disable the usage. So
593 only cgroup_disable=memory is actually worthy}
595 checkreqprot [SELINUX] Set initial checkreqprot flag value.
596 Format: { "0" | "1" }
597 See security/selinux/Kconfig help text.
598 0 -- check protection applied by kernel (includes
599 any implied execute protection).
600 1 -- check protection requested by application.
601 Default value is set via a kernel config option.
602 Value can be changed at runtime via
603 /selinux/checkreqprot.
606 See Documentation/s390/CommonIO for details.
609 Prevents the clock framework from automatically gating
610 clocks that have not been explicitly enabled by a Linux
611 device driver but are enabled in hardware at reset or
612 by the bootloader/firmware. Note that this does not
613 force such clocks to be always-on nor does it reserve
614 those clocks in any way. This parameter is useful for
615 debug and development, but should not be needed on a
616 platform with proper driver support. For more
617 information, see Documentation/clk.txt.
619 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
621 Forces specified clocksource (if available) to be used
622 when calculating gettimeofday(). If specified
623 clocksource is not available, it defaults to PIT.
624 Format: { pit | tsc | cyclone | pmtmr }
626 clocksource= Override the default clocksource
628 Override the default clocksource and use the clocksource
629 with the name specified.
630 Some clocksource names to choose from, depending on
632 [all] jiffies (this is the base, fallback clocksource)
634 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
635 pxa_timer,timer3,32k_counter,timer0_1
637 [X86-32] pit,hpet,tsc;
638 scx200_hrt on Geode; cyclone on IBM x440
646 clearcpuid=BITNUM [X86]
647 Disable CPUID feature X for the kernel. See
648 arch/x86/include/asm/cpufeature.h for the valid bit
649 numbers. Note the Linux specific bits are not necessarily
650 stable over kernel options, but the vendor specific
652 Also note that user programs calling CPUID directly
653 or using the feature without checking anything
654 will still see it. This just prevents it from
655 being used by the kernel or shown in /proc/cpuinfo.
656 Also note the kernel might malfunction if you disable
659 cma=nn[MG]@[start[MG][-end[MG]]]
661 Sets the size of kernel global memory area for
662 contiguous memory allocations and optionally the
663 placement constraint by the physical address range of
664 memory allocations. A value of 0 disables CMA
665 altogether. For more information, see
666 include/linux/dma-contiguous.h
668 cmo_free_hint= [PPC] Format: { yes | no }
669 Specify whether pages are marked as being inactive
670 when they are freed. This is used in CMO environments
671 to determine OS memory pressure for page stealing by
675 coherent_pool=nn[KMG] [ARM,KNL]
676 Sets the size of memory pool for coherent, atomic dma
677 allocations, by default set to 256K.
679 code_bytes [X86] How many bytes of object code to print
684 com20020= [HW,NET] ARCnet - COM20020 chipset
686 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
688 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
692 ARCnet - COM90xx chipset (memory-mapped buffers)
693 Format: <io>[,<irq>[,<memstart>]]
695 condev= [HW,S390] console device
698 console= [KNL] Output console device and options.
700 tty<n> Use the virtual console device <n>.
704 Use the specified serial port. The options are of
705 the form "bbbbpnf", where "bbbb" is the baud rate,
706 "p" is parity ("n", "o", or "e"), "n" is number of
707 bits, and "f" is flow control ("r" for RTS or
708 omit it). Default is "9600n8".
710 See Documentation/serial-console.txt for more
712 Documentation/networking/netconsole.txt for an
715 uart[8250],io,<addr>[,options]
716 uart[8250],mmio,<addr>[,options]
717 uart[8250],mmio32,<addr>[,options]
718 uart[8250],0x<addr>[,options]
719 Start an early, polled-mode console on the 8250/16550
720 UART at the specified I/O port or MMIO address,
721 switching to the matching ttyS device later.
722 MMIO inter-register address stride is either 8-bit
723 (mmio) or 32-bit (mmio32).
724 If none of [io|mmio|mmio32], <addr> is assumed to be
725 equivalent to 'mmio'. 'options' are specified in the
726 same format described for ttyS above; if unspecified,
727 the h/w is not re-initialized.
729 hvc<n> Use the hypervisor console device <n>. This is for
730 both Xen and PowerPC hypervisors.
732 If the device connected to the port is not a TTY but a braille
733 device, prepend "brl," before the device type, for instance
735 For now, only VisioBraille is supported.
737 consoleblank= [KNL] The console blank (screen saver) timeout in
738 seconds. Defaults to 10*60 = 10mins. A value of 0
739 disables the blank timer.
742 [KNL] Change the default value for
743 /proc/<pid>/coredump_filter.
744 See also Documentation/filesystems/proc.txt.
746 cpuidle.off=1 [CPU_IDLE]
747 disable the cpuidle sub-system
750 [X86] Delay for N microsec between assert and de-assert
751 of APIC INIT to start processors. This delay occurs
752 on every CPU online, such as boot, and resume from suspend.
755 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
757 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
759 crashkernel=size[KMG][@offset[KMG]]
760 [KNL] Using kexec, Linux can switch to a 'crash kernel'
761 upon panic. This parameter reserves the physical
762 memory region [offset, offset + size] for that kernel
763 image. If '@offset' is omitted, then a suitable offset
764 is selected automatically. Check
765 Documentation/kdump/kdump.txt for further details.
767 crashkernel=range1:size1[,range2:size2,...][@offset]
768 [KNL] Same as above, but depends on the memory
769 in the running system. The syntax of range is
770 start-[end] where start and end are both
771 a memory unit (amount[KMG]). See also
772 Documentation/kdump/kdump.txt for an example.
774 crashkernel=size[KMG],high
775 [KNL, x86_64] range could be above 4G. Allow kernel
776 to allocate physical memory region from top, so could
777 be above 4G if system have more than 4G ram installed.
778 Otherwise memory region will be allocated below 4G, if
780 It will be ignored if crashkernel=X is specified.
781 crashkernel=size[KMG],low
782 [KNL, x86_64] range under 4G. When crashkernel=X,high
783 is passed, kernel could allocate physical memory region
784 above 4G, that cause second kernel crash on system
785 that require some amount of low memory, e.g. swiotlb
786 requires at least 64M+32K low memory. Kernel would
787 try to allocate 72M below 4G automatically.
788 This one let user to specify own low range under 4G
789 for second kernel instead.
790 0: to disable low allocation.
791 It will be ignored when crashkernel=X,high is not used
792 or memory reserved is below 4G.
797 cs89x0_media= [HW,NET]
798 Format: { rj45 | aui | bnc }
801 See header of drivers/s390/block/dasd_devmap.c.
803 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
804 (one device per port)
805 Format: <port#>,<type>
806 See also Documentation/input/joystick-parport.txt
808 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
809 time. See Documentation/dynamic-debug-howto.txt for
810 details. Deprecated, see dyndbg.
812 debug [KNL] Enable kernel debugging (events log level).
815 [KNL] verbose self-tests
817 Print debugging info while doing the locking API
819 We default to 0 (no extra messages), setting it to
820 1 will print _a lot_ more information - normally
821 only useful to kernel developers.
823 debug_objects [KNL] Enable object debugging
826 [KNL] Disable object debugging
828 debug_guardpage_minorder=
829 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
830 parameter allows control of the order of pages that will
831 be intentionally kept free (and hence protected) by the
832 buddy allocator. Bigger value increase the probability
833 of catching random memory corruption, but reduce the
834 amount of memory for normal system use. The maximum
835 possible value is MAX_ORDER/2. Setting this parameter
836 to 1 or 2 should be enough to identify most random
837 memory corruption problems caused by bugs in kernel or
838 driver code when a CPU writes to (or reads from) a
839 random memory location. Note that there exists a class
840 of memory corruptions problems caused by buggy H/W or
841 F/W or by drivers badly programing DMA (basically when
842 memory is written at bus level and the CPU MMU is
843 bypassed) which are not detectable by
844 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
845 tracking down these problems.
848 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
849 parameter enables the feature at boot time. In
850 default, it is disabled. We can avoid allocating huge
851 chunk of memory for debug pagealloc if we don't enable
852 it at boot time and the system will work mostly same
853 with the kernel built without CONFIG_DEBUG_PAGEALLOC.
854 on: enable the feature
856 debugpat [X86] Enable PAT debugging
858 decnet.addr= [HW,NET]
859 Format: <area>[,<node>]
860 See also Documentation/networking/decnet.txt.
863 [same as hugepagesz=] The size of the default
864 HugeTLB page size. This is the size represented by
865 the legacy /proc/ hugepages APIs, used for SHM, and
866 default size when mounting hugetlbfs filesystems.
867 Defaults to the default architecture's huge page size
871 Set number of hash buckets for dentry cache.
874 See Documentation/networking/ipv6.txt.
876 disable_cpu_apicid= [X86,APIC,SMP]
878 The number of initial APIC ID for the
879 corresponding CPU to be disabled at boot,
880 mostly used for the kdump 2nd kernel to
881 disable BSP to wake up multiple CPUs without
882 causing system reset or hang due to sending
885 disable_ddw [PPC/PSERIES]
886 Disable Dynamic DMA Window support. Use this if
887 to workaround buggy firmware.
890 See Documentation/networking/ipv6.txt.
892 disable_mtrr_cleanup [X86]
893 The kernel tries to adjust MTRR layout from continuous
894 to discrete, to make X server driver able to add WB
895 entry later. This parameter disables that.
897 disable_mtrr_trim [X86, Intel and AMD only]
898 By default the kernel will trim any uncacheable
899 memory out of your available memory pool based on
900 MTRR settings. This parameter disables that behavior,
901 possibly causing your machine to run very slowly.
903 disable_timer_pin_1 [X86]
904 Disable PIN 1 of APIC timer
905 Can be useful to work around chipset bugs.
907 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
908 this option disables the debugging code at boot.
910 dma_debug_entries=<number>
911 This option allows to tune the number of preallocated
912 entries for DMA-API debugging code. One entry is
913 required per DMA-API allocation. Use this if the
914 DMA-API debugging code disables itself because the
915 architectural default is too low.
917 dma_debug_driver=<driver_name>
918 With this option the DMA-API debugging driver
919 filter feature can be enabled at boot time. Just
920 pass the driver to filter for as the parameter.
921 The filter can be disabled or changed to another
922 driver later using sysfs.
924 drm_kms_helper.edid_firmware=[<connector>:]<file>
925 Broken monitors, graphic adapters and KVMs may
926 send no or incorrect EDID data sets. This parameter
927 allows to specify an EDID data set in the
928 /lib/firmware directory that is used instead.
929 Generic built-in EDID data sets are used, if one of
930 edid/1024x768.bin, edid/1280x1024.bin,
931 edid/1680x1050.bin, or edid/1920x1080.bin is given
932 and no file with the same name exists. Details and
933 instructions how to build your own EDID data are
934 available in Documentation/EDID/HOWTO.txt. An EDID
935 data set will only be used for a particular connector,
936 if its name and a colon are prepended to the EDID
941 dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
942 module.dyndbg[="val"]
943 Enable debug messages at boot time. See
944 Documentation/dynamic-debug-howto.txt for details.
946 nompx [X86] Disables Intel Memory Protection Extensions.
947 See Documentation/x86/intel_mpx.txt for more
948 information about the feature.
951 on enable eager fpu restore
952 off disable eager fpu restore
953 auto selects the default scheme, which automatically
954 enables eagerfpu restore for xsaveopt.
956 module.async_probe [KNL]
957 Enable asynchronous probe on this module.
959 early_ioremap_debug [KNL]
960 Enable debug messages in early_ioremap support. This
961 is useful for tracking down temporary early mappings
962 which are not unmapped.
964 earlycon= [KNL] Output early console device and options.
967 Start an early, polled-mode console on a cadence serial
968 port at the specified address. The cadence serial port
969 must already be setup and configured. Options are not
972 uart[8250],io,<addr>[,options]
973 uart[8250],mmio,<addr>[,options]
974 uart[8250],mmio32,<addr>[,options]
975 uart[8250],0x<addr>[,options]
976 Start an early, polled-mode console on the 8250/16550
977 UART at the specified I/O port or MMIO address.
978 MMIO inter-register address stride is either 8-bit
979 (mmio) or 32-bit (mmio32).
980 If none of [io|mmio|mmio32], <addr> is assumed to be
981 equivalent to 'mmio'. 'options' are specified in the
982 same format described for "console=ttyS<n>"; if
983 unspecified, the h/w is not initialized.
986 Start an early, polled-mode console on a pl011 serial
987 port at the specified address. The pl011 serial port
988 must already be setup and configured. Options are not
992 Start an early, polled-mode console on an msm serial
993 port at the specified address. The serial port
994 must already be setup and configured. Options are not
998 Start an early, polled-mode console on an msm serial
999 dm port at the specified address. The serial port
1000 must already be setup and configured. Options are not
1003 smh Use ARM semihosting calls for early console.
1011 Use early console provided by serial driver available
1012 on Samsung SoCs, requires selecting proper type and
1013 a correct base address of the selected UART port. The
1014 serial port must already be setup and configured.
1015 Options are not yet supported.
1017 earlyprintk= [X86,SH,BLACKFIN,ARM,M68k]
1021 earlyprintk=serial[,ttySn[,baudrate]]
1022 earlyprintk=serial[,0x...[,baudrate]]
1023 earlyprintk=ttySn[,baudrate]
1024 earlyprintk=dbgp[debugController#]
1025 earlyprintk=pciserial,bus:device.function[,baudrate]
1027 earlyprintk is useful when the kernel crashes before
1028 the normal console is initialized. It is not enabled by
1029 default because it has some cosmetic problems.
1031 Append ",keep" to not disable it when the real console
1034 Only one of vga, efi, serial, or usb debug port can
1037 Currently only ttyS0 and ttyS1 may be specified by
1038 name. Other I/O ports may be explicitly specified
1039 on some architectures (x86 and arm at least) by
1040 replacing ttySn with an I/O port address, like this:
1041 earlyprintk=serial,0x1008,115200
1042 You can find the port for a given device in
1043 /proc/tty/driver/serial:
1044 2: uart:ST16650V2 port:00001008 irq:18 ...
1046 Interaction with the standard serial driver is not
1049 The VGA and EFI output is eventually overwritten by
1052 The xen output can only be used by Xen PV guests.
1054 edac_report= [HW,EDAC] Control how to report EDAC event
1055 Format: {"on" | "off" | "force"}
1056 on: enable EDAC to report H/W event. May be overridden
1057 by other higher priority error reporting module.
1058 off: disable H/W event reporting through EDAC.
1059 force: enforce the use of EDAC to report H/W event.
1062 ekgdboc= [X86,KGDB] Allow early kernel console debugging
1065 This is designed to be used in conjunction with
1066 the boot argument: earlyprintk=vga
1069 Format: {"off" | "on" | "skip[mbr]"}
1072 Format: { "old_map", "nochunk", "noruntime", "debug" }
1073 old_map [X86-64]: switch to the old ioremap-based EFI
1074 runtime services mapping. 32-bit still uses this one by
1076 nochunk: disable reading files in "chunks" in the EFI
1077 boot stub, as chunking can cause problems with some
1078 firmware implementations.
1079 noruntime : disable EFI runtime services support
1080 debug: enable misc debug output
1082 efi_no_storage_paranoia [EFI; X86]
1083 Using this parameter you can use more than 50% of
1084 your efi variable storage. Use this parameter only if
1085 you are really sure that your UEFI does sane gc and
1086 fulfills the spec otherwise your board may brick.
1088 eisa_irq_edge= [PARISC,HW]
1089 See header of drivers/parisc/eisa.c.
1092 See comment before function elanfreq_setup() in
1093 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
1096 Format: {"cfq" | "deadline" | "noop"}
1097 See Documentation/block/cfq-iosched.txt and
1098 Documentation/block/deadline-iosched.txt for details.
1100 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
1101 Specifies physical address of start of kernel core
1102 image elf header and optionally the size. Generally
1103 kexec loader will pass this option to capture kernel.
1104 See Documentation/kdump/kdump.txt for details.
1106 enable_mtrr_cleanup [X86]
1107 The kernel tries to adjust MTRR layout from continuous
1108 to discrete, to make X server driver able to add WB
1109 entry later. This parameter enables that.
1111 enable_timer_pin_1 [X86]
1112 Enable PIN 1 of APIC timer
1113 Can be useful to work around chipset bugs
1114 (in particular on some ATI chipsets).
1115 The kernel tries to set a reasonable default.
1117 enforcing [SELINUX] Set initial enforcing status.
1119 See security/selinux/Kconfig help text.
1120 0 -- permissive (log only, no denials).
1121 1 -- enforcing (deny and log).
1123 Value can be changed at runtime via /selinux/enforce.
1126 Disable Error Record Serialization Table (ERST)
1129 ether= [HW,NET] Ethernet cards parameters
1130 This option is obsoleted by the "netdev=" option, which
1131 has equivalent usage. See its documentation for details.
1135 Permit 'security.evm' to be updated regardless of
1136 current integrity status.
1140 fail_make_request=[KNL]
1141 General fault injection mechanism.
1142 Format: <interval>,<probability>,<space>,<times>
1143 See also Documentation/fault-injection/.
1146 See Documentation/blockdev/floppy.txt.
1148 force_pal_cache_flush
1149 [IA-64] Avoid check_sal_cache_flush which may hang on
1150 buggy SAL_CACHE_FLUSH implementations. Using this
1151 parameter will force ia64_sal_cache_flush to call
1152 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
1155 Forcefully enable Physical Address Extension (PAE).
1156 Many Pentium M systems disable PAE but may have a
1157 functionally usable PAE implementation.
1158 Warning: use of this parameter will taint the kernel
1159 and may cause unknown problems.
1162 [FTRACE] will set and start the specified tracer
1163 as early as possible in order to facilitate early
1166 ftrace_dump_on_oops[=orig_cpu]
1167 [FTRACE] will dump the trace buffers on oops.
1168 If no parameter is passed, ftrace will dump
1169 buffers of all CPUs, but if you pass orig_cpu, it will
1170 dump only the buffer of the CPU that triggered the
1173 ftrace_filter=[function-list]
1174 [FTRACE] Limit the functions traced by the function
1175 tracer at boot up. function-list is a comma separated
1176 list of functions. This list can be changed at run
1177 time by the set_ftrace_filter file in the debugfs
1180 ftrace_notrace=[function-list]
1181 [FTRACE] Do not trace the functions specified in
1182 function-list. This list can be changed at run time
1183 by the set_ftrace_notrace file in the debugfs
1186 ftrace_graph_filter=[function-list]
1187 [FTRACE] Limit the top level callers functions traced
1188 by the function graph tracer at boot up.
1189 function-list is a comma separated list of functions
1190 that can be changed at run time by the
1191 set_graph_function file in the debugfs tracing directory.
1193 ftrace_graph_notrace=[function-list]
1194 [FTRACE] Do not trace from the functions specified in
1195 function-list. This list is a comma separated list of
1196 functions that can be changed at run time by the
1197 set_graph_notrace file in the debugfs tracing directory.
1200 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
1201 support via parallel port (up to 5 devices per port)
1202 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
1203 See also Documentation/input/joystick-parport.txt
1207 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
1211 gcov_persist= [GCOV] When non-zero (default), profiling data for
1212 kernel modules is saved and remains accessible via
1213 debugfs, even when the module is unloaded/reloaded.
1214 When zero, profiling data is discarded and associated
1215 debugfs files are removed at module unload time.
1217 gpt [EFI] Forces disk with valid GPT signature but
1218 invalid Protective MBR to be treated as GPT. If the
1219 primary GPT is corrupted, it enables the backup/alternate
1220 GPT to be used instead.
1222 grcan.enable0= [HW] Configuration of physical interface 0. Determines
1223 the "Enable 0" bit of the configuration register.
1226 grcan.enable1= [HW] Configuration of physical interface 1. Determines
1227 the "Enable 0" bit of the configuration register.
1230 grcan.select= [HW] Select which physical interface to use.
1233 grcan.txsize= [HW] Sets the size of the tx buffer.
1234 Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
1236 grcan.rxsize= [HW] Sets the size of the rx buffer.
1237 Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
1240 hashdist= [KNL,NUMA] Large hashes allocated during boot
1241 are distributed across NUMA nodes. Defaults on
1242 for 64-bit NUMA, off otherwise.
1243 Format: 0 | 1 (for off | on)
1245 hcl= [IA-64] SGI's Hardware Graph compatibility layer
1247 hd= [EIDE] (E)IDE hard drive subsystem geometry
1248 Format: <cyl>,<head>,<sect>
1251 Disable Hardware Error Source Table (HEST) support;
1252 corresponding firmware-first mode error processing
1253 logic will be disabled.
1255 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
1256 size of <nn>. This works even on boxes that have no
1257 highmem otherwise. This also works to reduce highmem
1258 size on bigger boxes.
1260 highres= [KNL] Enable/disable high resolution timer mode.
1261 Valid parameters: "on", "off"
1265 See Documentation/isdn/README.HiSax.
1269 hpet= [X86-32,HPET] option to control HPET usage
1270 Format: { enable (default) | disable | force |
1272 disable: disable HPET and use PIT instead
1273 force: allow force enabled of undocumented chips (ICH4,
1275 verbose: show contents of HPET registers during setup
1277 hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET
1278 registers. Default set by CONFIG_HPET_MMAP_DEFAULT.
1280 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
1281 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
1282 On x86-64 and powerpc, this option can be specified
1283 multiple times interleaved with hugepages= to reserve
1284 huge pages of different sizes. Valid pages sizes on
1285 x86-64 are 2M (when the CPU supports "pse") and 1G
1286 (when the CPU supports the "pdpe1gb" cpuinfo flag).
1288 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
1289 terminal devices. Valid values: 0..8
1290 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
1291 If specified, z/VM IUCV HVC accepts connections
1292 from listed z/VM user IDs only.
1294 hwthread_map= [METAG] Comma-separated list of Linux cpu id to
1295 hardware thread id mappings.
1296 Format: <cpu>:<hwthread>
1299 Do not unregister boot console at start. This is only
1300 useful for debugging when something happens in the window
1301 between unregistering the boot console and initializing
1304 i2c_bus= [HW] Override the default board specific I2C bus speed
1305 or register an additional I2C bus that is not
1306 registered from board initialization code.
1310 i8042.debug [HW] Toggle i8042 debug mode
1311 i8042.direct [HW] Put keyboard port into non-translated mode
1312 i8042.dumbkbd [HW] Pretend that controller can only read data from
1313 keyboard and cannot control its state
1314 (Don't attempt to blink the leds)
1315 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
1316 i8042.nokbd [HW] Don't check/create keyboard port
1317 i8042.noloop [HW] Disable the AUX Loopback command while probing
1319 i8042.nomux [HW] Don't check presence of an active multiplexing
1321 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
1323 i8042.notimeout [HW] Ignore timeout condition signalled by controller
1324 i8042.reset [HW] Reset the controller during init and cleanup
1325 i8042.unlock [HW] Unlock (ignore) the keylock
1326 i8042.kbdreset [HW] Reset device connected to KBD port
1330 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
1331 indicates that the driver is running on unsupported
1333 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
1334 does not match list of supported models.
1336 [HW] Report power status in /proc/i8k
1337 (disabled by default)
1338 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
1341 i915.invert_brightness=
1342 [DRM] Invert the sense of the variable that is used to
1343 set the brightness of the panel backlight. Normally a
1344 brightness value of 0 indicates backlight switched off,
1345 and the maximum of the brightness value sets the backlight
1346 to maximum brightness. If this parameter is set to 0
1347 (default) and the machine requires it, or this parameter
1348 is set to 1, a brightness value of 0 sets the backlight
1349 to maximum brightness, and the maximum of the brightness
1350 value switches the backlight off.
1351 -1 -- never invert brightness
1352 0 -- machine default
1353 1 -- force brightness inversion
1356 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
1358 ide-core.nodma= [HW] (E)IDE subsystem
1359 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
1360 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
1361 .cdrom .chs .ignore_cable are additional options
1362 See Documentation/ide/ide.txt.
1364 ide-generic.probe-mask= [HW] (E)IDE subsystem
1366 Probe mask for legacy ISA IDE ports. Depending on
1367 platform up to 6 ports are supported, enabled by
1368 setting corresponding bits in the mask to 1. The
1369 default value is 0x0, which has a special meaning.
1370 On systems that have PCI, it triggers scanning the
1371 PCI bus for the first and the second port, which
1372 are then probed. On systems without PCI the value
1373 of 0x0 enables probing the two first ports as if it
1376 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1377 Claim all unknown PCI IDE storage controllers.
1380 Format: idle=poll, idle=halt, idle=nomwait
1381 Poll forces a polling idle loop that can slightly
1382 improve the performance of waking up a idle CPU, but
1383 will use a lot of power and make the system run hot.
1385 idle=halt: Halt is forced to be used for CPU idle.
1386 In such case C2/C3 won't be used again.
1387 idle=nomwait: Disable mwait for CPU C-states
1389 ignore_loglevel [KNL]
1390 Ignore loglevel setting - this will print /all/
1391 kernel messages to the console. Useful for debugging.
1392 We also add it as printk module parameter, so users
1393 could change it dynamically, usually by
1394 /sys/module/printk/parameters/ignore_loglevel.
1396 ihash_entries= [KNL]
1397 Set number of hash buckets for inode cache.
1399 ima_appraise= [IMA] appraise integrity measurements
1400 Format: { "off" | "enforce" | "fix" | "log" }
1403 ima_appraise_tcb [IMA]
1404 The builtin appraise policy appraises all files
1408 Format: { md5 | sha1 | rmd160 | sha256 | sha384
1412 The list of supported hash algorithms is defined
1413 in crypto/hash_info.h.
1416 Load a policy which meets the needs of the Trusted
1417 Computing Base. This means IMA will measure all
1418 programs exec'd, files mmap'd for exec, and all files
1419 opened for read by uid=0.
1422 Select one of defined IMA measurements template formats.
1423 Formats: { "ima" | "ima-ng" }
1427 [IMA] Define a custom template format.
1428 Format: { "field1|...|fieldN" }
1430 ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage
1431 Format: <min_file_size>
1432 Set the minimal file size for using asynchronous hash.
1433 If left unspecified, ahash usage is disabled.
1435 ahash performance varies for different data sizes on
1436 different crypto accelerators. This option can be used
1437 to achieve the best performance for a particular HW.
1439 ima.ahash_bufsize= [IMA] Asynchronous hash buffer size
1441 Set hashing buffer size. Default: 4k.
1443 ahash performance varies for different chunk sizes on
1444 different crypto accelerators. This option can be used
1445 to achieve best performance for particular HW.
1449 Run specified binary instead of /sbin/init as init
1452 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1453 for working out where the kernel is dying during
1456 initcall_blacklist= [KNL] Do not execute a comma-separated list of
1457 initcall functions. Useful for debugging built-in
1458 modules and initcalls.
1460 initrd= [BOOT] Specify the location of the initial ramdisk
1462 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1465 int_pln_enable [x86] Enable power limit notification interrupt
1467 integrity_audit=[IMA]
1468 Format: { "0" | "1" }
1469 0 -- basic integrity auditing messages. (Default)
1470 1 -- additional integrity auditing messages.
1472 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1474 Enable intel iommu driver.
1476 Disable intel iommu driver.
1477 igfx_off [Default Off]
1478 By default, gfx is mapped as normal device. If a gfx
1479 device has a dedicated DMAR unit, the DMAR unit is
1480 bypassed by not enabling DMAR with this option. In
1481 this case, gfx device will use physical address for
1484 With this option iommu will not optimize to look
1485 for io virtual address below 32-bit forcing dual
1486 address cycle on pci bus for cards supporting greater
1487 than 32-bit addressing. The default is to look
1488 for translation below 32-bit and if not available
1489 then look in the higher range.
1490 strict [Default Off]
1491 With this option on every unmap_single operation will
1492 result in a hardware IOTLB flush operation as opposed
1493 to batching them for performance.
1494 sp_off [Default Off]
1495 By default, super page will be supported if Intel IOMMU
1496 has the capability. With this option, super page will
1498 ecs_off [Default Off]
1499 By default, extended context tables will be supported if
1500 the hardware advertises that it has support both for the
1501 extended tables themselves, and also PASID support. With
1502 this option set, extended tables will not be used even
1503 on hardware which claims to support them.
1505 intel_idle.max_cstate= [KNL,HW,ACPI,X86]
1506 0 disables intel_idle and fall back on acpi_idle.
1507 1 to 6 specify maximum depth of C-state.
1511 Do not enable intel_pstate as the default
1512 scaling driver for the supported processors
1514 Enable intel_pstate on systems that prohibit it by default
1515 in favor of acpi-cpufreq. Forcing the intel_pstate driver
1516 instead of acpi-cpufreq may disable platform features, such
1517 as thermal controls and power capping, that rely on ACPI
1518 P-States information being indicated to OSPM and therefore
1519 should be used with caution. This option does not work with
1520 processors that aren't supported by the intel_pstate driver
1521 or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
1523 Do not enable hardware P state control (HWP)
1526 Only load intel_pstate on systems which support
1527 hardware P state control (HWP) if available.
1529 intremap= [X86-64, Intel-IOMMU]
1530 on enable Interrupt Remapping (default)
1531 off disable Interrupt Remapping
1532 nosid disable Source ID checking
1534 BIOS x2APIC opt-out request will be ignored
1536 iomem= Disable strict checking of access to MMIO memory
1537 strict regions from userspace.
1552 nobypass [PPC/POWERNV]
1553 Disable IOMMU bypass, using IOMMU for PCI devices.
1556 io7= [HW] IO7 for Marvel based alpha systems
1557 See comment before marvel_specify_io7 in
1558 arch/alpha/kernel/core_marvel.c.
1560 io_delay= [X86] I/O delay method
1562 Standard port 0x80 based delay
1564 Alternate port 0xed based delay (needed on some systems)
1566 Simple two microseconds delay
1571 See Documentation/filesystems/nfs/nfsroot.txt.
1574 When an interrupt is not handled search all handlers
1575 for it. Intended to get systems with badly broken
1579 When an interrupt is not handled search all handlers
1580 for it. Also check all handlers each timer
1581 interrupt. Intended to get systems with badly broken
1585 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1587 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1589 <cpu number>,...,<cpu number>
1591 <cpu number>-<cpu number>
1592 (must be a positive range in ascending order)
1594 <cpu number>,...,<cpu number>-<cpu number>
1596 This option can be used to specify one or more CPUs
1597 to isolate from the general SMP balancing and scheduling
1598 algorithms. You can move a process onto or off an
1599 "isolated" CPU via the CPU affinity syscalls or cpuset.
1600 <cpu number> begins at 0 and the maximum value is
1601 "number of CPUs in system - 1".
1603 This option is the preferred way to isolate CPUs. The
1604 alternative -- manually setting the CPU mask of all
1605 tasks in the system -- can cause problems and
1606 suboptimal load balancer performance.
1610 ivrs_ioapic [HW,X86_64]
1611 Provide an override to the IOAPIC-ID<->DEVICE-ID
1612 mapping provided in the IVRS ACPI table. For
1613 example, to map IOAPIC-ID decimal 10 to
1614 PCI device 00:14.0 write the parameter as:
1615 ivrs_ioapic[10]=00:14.0
1617 ivrs_hpet [HW,X86_64]
1618 Provide an override to the HPET-ID<->DEVICE-ID
1619 mapping provided in the IVRS ACPI table. For
1620 example, to map HPET-ID decimal 0 to
1621 PCI device 00:14.0 write the parameter as:
1622 ivrs_hpet[0]=00:14.0
1624 js= [HW,JOY] Analog joystick
1625 See Documentation/input/joystick.txt.
1628 Enable/disable kernel and module base offset ASLR
1629 (Address Space Layout Randomization) if built into
1630 the kernel. When CONFIG_HIBERNATION is selected,
1631 kASLR is disabled by default. When kASLR is enabled,
1632 hibernation will be disabled.
1636 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1637 specifies the amount of memory usable by the kernel
1638 for non-movable allocations. The requested amount is
1639 spread evenly throughout all nodes in the system. The
1640 remaining memory in each node is used for Movable
1641 pages. In the event, a node is too small to have both
1642 kernelcore and Movable pages, kernelcore pages will
1643 take priority and other nodes will have a larger number
1644 of Movable pages. The Movable zone is used for the
1645 allocation of pages that may be reclaimed or moved
1646 by the page migration subsystem. This means that
1647 HugeTLB pages may not be allocated from this zone.
1648 Note that allocations like PTEs-from-HighMem still
1649 use the HighMem zone if it exists, and the Normal
1650 zone if it does not.
1652 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1653 Format: <Controller#>[,poll interval]
1654 The controller # is the number of the ehci usb debug
1655 port as it is probed via PCI. The poll interval is
1656 optional and is the number seconds in between
1657 each poll cycle to the debug port in case you need
1658 the functionality for interrupting the kernel with
1659 gdb or control-c on the dbgp connection. When
1660 not using this parameter you use sysrq-g to break into
1661 the kernel debugger.
1663 kgdboc= [KGDB,HW] kgdb over consoles.
1664 Requires a tty driver that supports console polling,
1665 or a supported polling keyboard driver (non-usb).
1666 Serial only format: <serial_device>[,baud]
1667 keyboard only format: kbd
1668 keyboard and serial format: kbd,<serial_device>[,baud]
1669 Optional Kernel mode setting:
1670 kms, kbd format: kms,kbd
1671 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1673 kgdbwait [KGDB] Stop kernel execution and enter the
1674 kernel debugger at the earliest opportunity.
1676 kmac= [MIPS] korina ethernet MAC address.
1677 Configure the RouterBoard 532 series on-chip
1678 Ethernet adapter MAC address.
1680 kmemleak= [KNL] Boot-time kmemleak enable/disable
1681 Valid arguments: on, off
1683 Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
1686 kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode
1687 Valid arguments: 0, 1, 2
1688 kmemcheck=0 (disabled)
1689 kmemcheck=1 (enabled)
1690 kmemcheck=2 (one-shot mode)
1691 Default: 2 (one-shot mode)
1693 kstack=N [X86] Print N words from the kernel stack
1696 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1697 Default is 0 (don't ignore, but inject #GP)
1699 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1703 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1704 Default is 1 (enabled)
1706 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1708 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1710 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1711 (virtualized MMU) support on capable Intel chips.
1712 Default is 1 (enabled)
1714 kvm-intel.emulate_invalid_guest_state=
1715 [KVM,Intel] Enable emulation of invalid guest states
1716 Default is 0 (disabled)
1718 kvm-intel.flexpriority=
1719 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1720 Default is 1 (enabled)
1723 [KVM,Intel] Enable VMX nesting (nVMX).
1724 Default is 0 (disabled)
1726 kvm-intel.unrestricted_guest=
1727 [KVM,Intel] Disable unrestricted guest feature
1728 (virtualized real and unpaged mode) on capable
1729 Intel chips. Default is 1 (enabled)
1731 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1732 feature (tagged TLBs) on capable Intel chips.
1733 Default is 1 (enabled)
1739 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1742 lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline
1743 value for LAPIC timer one-shot implementation. Default
1744 back to the programmable timer unit in the LAPIC.
1746 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1749 libata.dma= [LIBATA] DMA control
1750 libata.dma=0 Disable all PATA and SATA DMA
1751 libata.dma=1 PATA and SATA Disk DMA only
1752 libata.dma=2 ATAPI (CDROM) DMA only
1753 libata.dma=4 Compact Flash DMA only
1754 Combinations also work, so libata.dma=3 enables DMA
1755 for disks and CDROMs, but not CFs.
1757 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1758 libata.ignore_hpa=0 keep BIOS limits (default)
1759 libata.ignore_hpa=1 ignore limits, using full disk
1761 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1765 libata.force= [LIBATA] Force configurations. The format is comma
1766 separated list of "[ID:]VAL" where ID is
1767 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1768 matching port, link or device. Basically, it matches
1769 the ATA ID string printed on console by libata. If
1770 the whole ID part is omitted, the last PORT and DEVICE
1771 values are used. If ID hasn't been specified yet, the
1772 configuration applies to all ports, links and devices.
1774 If only DEVICE is omitted, the parameter applies to
1775 the port and all links and devices behind it. DEVICE
1776 number of 0 either selects the first device or the
1777 first fan-out link behind PMP device. It does not
1778 select the host link. DEVICE number of 15 selects the
1779 host link and device attached to it.
1781 The VAL specifies the configuration to force. As long
1782 as there's no ambiguity shortcut notation is allowed.
1783 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1784 The following configurations can be forced.
1786 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1787 Any ID with matching PORT is used.
1789 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1791 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1792 udma[/][16,25,33,44,66,100,133] notation is also
1795 * [no]ncq: Turn on or off NCQ.
1797 * [no]ncqtrim: Turn off queued DSM TRIM.
1799 * nohrst, nosrst, norst: suppress hard, soft
1802 * rstonce: only attempt one reset during
1803 hot-unplug link recovery
1805 * dump_id: dump IDENTIFY data.
1807 * atapi_dmadir: Enable ATAPI DMADIR bridge support
1809 * disable: Disable this device.
1811 If there are multiple matching configurations changing
1812 the same attribute, the last one is used.
1814 memblock=debug [KNL] Enable memblock debug messages.
1816 load_ramdisk= [RAM] List of ramdisks to load from floppy
1817 See Documentation/blockdev/ramdisk.txt.
1819 lockd.nlm_grace_period=P [NFS] Assign grace period.
1822 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1825 lockd.nlm_timeout=T [NFS] Assign timeout value.
1828 lockd.nlm_udpport=M [NFS] Assign UDP port.
1831 locktorture.nreaders_stress= [KNL]
1832 Set the number of locking read-acquisition kthreads.
1833 Defaults to being automatically set based on the
1834 number of online CPUs.
1836 locktorture.nwriters_stress= [KNL]
1837 Set the number of locking write-acquisition kthreads.
1839 locktorture.onoff_holdoff= [KNL]
1840 Set time (s) after boot for CPU-hotplug testing.
1842 locktorture.onoff_interval= [KNL]
1843 Set time (s) between CPU-hotplug operations, or
1844 zero to disable CPU-hotplug testing.
1846 locktorture.shuffle_interval= [KNL]
1847 Set task-shuffle interval (jiffies). Shuffling
1848 tasks allows some CPUs to go into dyntick-idle
1849 mode during the locktorture test.
1851 locktorture.shutdown_secs= [KNL]
1852 Set time (s) after boot system shutdown. This
1853 is useful for hands-off automated testing.
1855 locktorture.stat_interval= [KNL]
1856 Time (s) between statistics printk()s.
1858 locktorture.stutter= [KNL]
1859 Time (s) to stutter testing, for example,
1860 specifying five seconds causes the test to run for
1861 five seconds, wait for five seconds, and so on.
1862 This tests the locking primitive's ability to
1863 transition abruptly to and from idle.
1865 locktorture.torture_runnable= [BOOT]
1866 Start locktorture running at boot time.
1868 locktorture.torture_type= [KNL]
1869 Specify the locking implementation to test.
1871 locktorture.verbose= [KNL]
1872 Enable additional printk() statements.
1874 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1877 loglevel= All Kernel Messages with a loglevel smaller than the
1878 console loglevel will be printed to the console. It can
1879 also be changed with klogd or other programs. The
1880 loglevels are defined as follows:
1882 0 (KERN_EMERG) system is unusable
1883 1 (KERN_ALERT) action must be taken immediately
1884 2 (KERN_CRIT) critical conditions
1885 3 (KERN_ERR) error conditions
1886 4 (KERN_WARNING) warning conditions
1887 5 (KERN_NOTICE) normal but significant condition
1888 6 (KERN_INFO) informational
1889 7 (KERN_DEBUG) debug-level messages
1891 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1892 in bytes. n must be a power of two and greater
1893 than the minimal size. The minimal size is defined
1894 by LOG_BUF_SHIFT kernel config parameter. There is
1895 also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
1896 that allows to increase the default size depending on
1897 the number of CPUs. See init/Kconfig for more details.
1899 logo.nologo [FB] Disables display of the built-in Linux logo.
1900 This may be used to provide more screen space for
1901 kernel log messages and is useful when debugging
1902 kernel boot problems.
1904 lp=0 [LP] Specify parallel ports to use, e.g,
1905 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1906 lp=reset first parallel port). 'lp=0' disables the
1907 lp=auto printer driver. 'lp=reset' (which can be
1908 specified in addition to the ports) causes
1909 attached printers to be reset. Using
1910 lp=port1,port2,... specifies the parallel ports
1911 to associate lp devices with, starting with
1912 lp0. A port specification may be 'none' to skip
1913 that lp device, or a parport name such as
1914 'parport0'. Specifying 'lp=auto' instead of a
1915 port specification list means that device IDs
1916 from each port should be examined, to see if
1917 an IEEE 1284-compliant printer is attached; if
1918 so, the driver will manage that printer.
1919 See also header of drivers/char/lp.c.
1922 Sets loops_per_jiffy to given constant, thus avoiding
1923 time-consuming boot-time autodetection (up to 250 ms per
1924 CPU). 0 enables autodetection (default). To determine
1925 the correct value for your kernel, boot with normal
1926 autodetection and see what value is printed. Note that
1927 on SMP systems the preset will be applied to all CPUs,
1928 which is likely to cause problems if your CPUs need
1929 significantly divergent settings. An incorrect value
1930 will cause delays in the kernel to be wrong, leading to
1931 unpredictable I/O errors and other breakage. Although
1932 unlikely, in the extreme case this might damage your
1936 Format: <io>,<irq>,<dma>
1938 machvec= [IA-64] Force the use of a particular machine-vector
1939 (machvec) in a generic kernel.
1940 Example: machvec=hpzx1_swiotlb
1942 machtype= [Loongson] Share the same kernel image file between different
1944 Example: machtype=lemote-yeeloong-2f-7inch
1946 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1947 than or equal to this physical address is ignored.
1949 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1950 should make use of. maxcpus=n : n >= 0 limits the
1951 kernel to using 'n' processors. n=0 is a special case,
1952 it is equivalent to "nosmp", which also disables
1955 max_loop= [LOOP] The number of loop block devices that get
1956 (loop.max_loop) unconditionally pre-created at init time. The default
1957 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1958 of statically allocating a predefined number, loop
1959 devices can be requested on-demand with the
1960 /dev/loop-control interface.
1962 mce [X86-32] Machine Check Exception
1964 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1966 md= [HW] RAID subsystems devices and level
1967 See Documentation/md.txt.
1970 Format: <first>,<last>
1971 Specifies range of consoles to be captured by the MDA.
1973 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1974 Amount of memory to be used when the kernel is not able
1975 to see the whole system memory or for test.
1976 [X86] Work as limiting max address. Use together
1977 with memmap= to avoid physical address space collisions.
1978 Without memmap= PCI devices could be placed at addresses
1979 belonging to unused RAM.
1981 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1985 [KNL,SH] Allow user to override the default size for
1986 per-device physically contiguous DMA buffers.
1988 memmap=exactmap [KNL,X86] Enable setting of an exact
1989 E820 memory map, as specified by the user.
1990 Such memmap=exactmap lines can be constructed based on
1991 BIOS output or other requirements. See the memmap=nn@ss
1994 memmap=nn[KMG]@ss[KMG]
1995 [KNL] Force usage of a specific region of memory.
1996 Region of memory to be used is from ss to ss+nn.
1998 memmap=nn[KMG]#ss[KMG]
1999 [KNL,ACPI] Mark specific memory as ACPI data.
2000 Region of memory to be marked is from ss to ss+nn.
2002 memmap=nn[KMG]$ss[KMG]
2003 [KNL,ACPI] Mark specific memory as reserved.
2004 Region of memory to be reserved is from ss to ss+nn.
2005 Example: Exclude memory from 0x18690000-0x1869ffff
2006 memmap=64K$0x18690000
2008 memmap=0x10000$0x18690000
2010 memmap=nn[KMG]!ss[KMG]
2011 [KNL,X86] Mark specific memory as protected.
2012 Region of memory to be used, from ss to ss+nn.
2013 The memory region may be marked as e820 type 12 (0xc)
2014 and is NVDIMM or ADR memory.
2016 memory_corruption_check=0/1 [X86]
2017 Some BIOSes seem to corrupt the first 64k of
2018 memory when doing things like suspend/resume.
2019 Setting this option will scan the memory
2020 looking for corruption. Enabling this will
2021 both detect corruption and prevent the kernel
2022 from using the memory being corrupted.
2023 However, its intended as a diagnostic tool; if
2024 repeatable BIOS-originated corruption always
2025 affects the same memory, you can use memmap=
2026 to prevent the kernel from using that memory.
2028 memory_corruption_check_size=size [X86]
2029 By default it checks for corruption in the low
2030 64k, making this memory unavailable for normal
2031 use. Use this parameter to scan for
2032 corruption in more or less memory.
2034 memory_corruption_check_period=seconds [X86]
2035 By default it checks for corruption every 60
2036 seconds. Use this parameter to check at some
2037 other rate. 0 disables periodic checking.
2039 memtest= [KNL,X86,ARM] Enable memtest
2041 default : 0 <disable>
2042 Specifies the number of memtest passes to be
2043 performed. Each pass selects another test
2044 pattern from a given set of patterns. Memtest
2045 fills the memory with this pattern, validates
2046 memory contents and reserves bad memory
2047 regions that are detected.
2049 meye.*= [HW] Set MotionEye Camera parameters
2050 See Documentation/video4linux/meye.txt.
2052 mfgpt_irq= [IA-32] Specify the IRQ to use for the
2053 Multi-Function General Purpose Timers on AMD Geode
2056 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
2057 the BIOS has incorrectly applied a workaround. TinyBIOS
2058 version 0.98 is known to be affected, 0.99 fixes the
2059 problem by letting the user disable the workaround.
2063 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
2064 physical address is ignored.
2066 mini2440= [ARM,HW,KNL]
2067 Format:[0..2][b][c][t]
2069 MINI2440 configuration specification:
2070 0 - The attached screen is the 3.5" TFT
2071 1 - The attached screen is the 7" TFT
2072 2 - The VGA Shield is attached (1024x768)
2073 Leaving out the screen size parameter will not load
2074 the TFT driver, and the framebuffer will be left
2076 b - Enable backlight. The TFT backlight pin will be
2077 linked to the kernel VESA blanking code and a GPIO
2078 LED. This parameter is not necessary when using the
2080 c - Enable the s3c camera interface.
2081 t - Reserved for enabling touchscreen support. The
2082 touchscreen support is not enabled in the mainstream
2083 kernel as of 2.6.30, a preliminary port can be found
2084 in the "bleeding edge" mini2440 support kernel at
2085 http://repo.or.cz/w/linux-2.6/mini2440.git
2088 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
2089 parameter allows control of the logging verbosity for
2090 the additional memory initialisation checks. A value
2091 of 0 disables mminit logging and a level of 4 will
2092 log everything. Information is printed at KERN_DEBUG
2093 so loglevel=8 may also need to be specified.
2096 [KNL] When CONFIG_MODULE_SIG is set, this means that
2097 modules without (valid) signatures will fail to load.
2098 Note that if CONFIG_MODULE_SIG_FORCE is set, that
2099 is always true, so this option does nothing.
2102 [MOUSE] Maximum time between finger touching and
2103 leaving touchpad surface for touch to be considered
2104 a tap and be reported as a left button click (for
2105 touchpads working in absolute mode only).
2107 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
2108 reporting absolute coordinates, such as tablets
2109 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
2110 reporting absolute coordinates, such as tablets
2112 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
2113 is similar to kernelcore except it specifies the
2114 amount of memory used for migratable allocations.
2115 If both kernelcore and movablecore is specified,
2116 then kernelcore will be at *least* the specified
2117 value but may be more. If movablecore on its own
2118 is specified, the administrator must be careful
2119 that the amount of memory usable for all allocations
2122 movable_node [KNL,X86] Boot-time switch to enable the effects
2123 of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
2125 MTD_Partition= [MTD]
2126 Format: <name>,<region-number>,<size>,<offset>
2128 MTD_Region= [MTD] Format:
2129 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
2132 See drivers/mtd/cmdlinepart.c.
2134 multitce=off [PPC] This parameter disables the use of the pSeries
2135 firmware feature for updating multiple TCE entries
2138 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
2140 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
2142 boundary - index of last SLC block on Flex-OneNAND.
2143 The remaining blocks are configured as MLC blocks.
2144 lock - Configure if Flex-OneNAND boundary should be locked.
2145 Once locked, the boundary cannot be changed.
2146 1 indicates lock status, 0 indicates unlock status.
2149 ARM/S3C2412 JIVE boot control
2151 See arch/arm/mach-s3c2412/mach-jive.c
2153 mtouchusb.raw_coordinates=
2154 [HW] Make the MicroTouch USB driver use raw coordinates
2155 ('y', default) or cooked coordinates ('n')
2157 mtrr_chunk_size=nn[KMG] [X86]
2158 used for mtrr cleanup. It is largest continuous chunk
2159 that could hold holes aka. UC entries.
2161 mtrr_gran_size=nn[KMG] [X86]
2162 Used for mtrr cleanup. It is granularity of mtrr block.
2164 Large value could prevent small alignment from
2167 mtrr_spare_reg_nr=n [X86]
2169 Range: 0,7 : spare reg number
2171 Used for mtrr cleanup. It is spare mtrr entries number.
2172 Set to 2 or more if your graphical card needs more.
2174 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
2176 netdev= [NET] Network devices parameters
2177 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
2178 Note that mem_start is often overloaded to mean
2179 something different and driver-specific.
2180 This usage is only documented in each driver source
2184 [NETFILTER] Enable connection tracking flow accounting
2185 0 to disable accounting
2186 1 to enable accounting
2189 nfsaddrs= [NFS] Deprecated. Use ip= instead.
2190 See Documentation/filesystems/nfs/nfsroot.txt.
2192 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
2193 See Documentation/filesystems/nfs/nfsroot.txt.
2195 nfsrootdebug [NFS] enable nfsroot debugging messages.
2196 See Documentation/filesystems/nfs/nfsroot.txt.
2198 nfs.callback_tcpport=
2199 [NFS] set the TCP port on which the NFSv4 callback
2200 channel should listen.
2203 [NFS] sets the pathname to the program which is used
2204 to update the NFS client cache entries.
2206 nfs.cache_getent_timeout=
2207 [NFS] sets the timeout after which an attempt to
2208 update a cache entry is deemed to have failed.
2210 nfs.idmap_cache_timeout=
2211 [NFS] set the maximum lifetime for idmapper cache
2215 [NFS] enable 64-bit inode numbers.
2216 If zero, the NFS client will fake up a 32-bit inode
2217 number for the readdir() and stat() syscalls instead
2218 of returning the full 64-bit number.
2219 The default is to return 64-bit inode numbers.
2221 nfs.max_session_slots=
2222 [NFSv4.1] Sets the maximum number of session slots
2223 the client will attempt to negotiate with the server.
2224 This limits the number of simultaneous RPC requests
2225 that the client can send to the NFSv4.1 server.
2226 Note that there is little point in setting this
2227 value higher than the max_tcp_slot_table_limit.
2229 nfs.nfs4_disable_idmapping=
2230 [NFSv4] When set to the default of '1', this option
2231 ensures that both the RPC level authentication
2232 scheme and the NFS level operations agree to use
2233 numeric uids/gids if the mount is using the
2234 'sec=sys' security flavour. In effect it is
2235 disabling idmapping, which can make migration from
2236 legacy NFSv2/v3 systems to NFSv4 easier.
2237 Servers that do not support this mode of operation
2238 will be autodetected by the client, and it will fall
2239 back to using the idmapper.
2240 To turn off this behaviour, set the value to '0'.
2242 [NFS4] Specify an additional fixed unique ident-
2243 ification string that NFSv4 clients can insert into
2244 their nfs_client_id4 string. This is typically a
2245 UUID that is generated at system install time.
2247 nfs.send_implementation_id =
2248 [NFSv4.1] Send client implementation identification
2249 information in exchange_id requests.
2250 If zero, no implementation identification information
2252 The default is to send the implementation identification
2255 nfs.recover_lost_locks =
2256 [NFSv4] Attempt to recover locks that were lost due
2257 to a lease timeout on the server. Please note that
2258 doing this risks data corruption, since there are
2259 no guarantees that the file will remain unchanged
2260 after the locks are lost.
2261 If you want to enable the kernel legacy behaviour of
2262 attempting to recover these locks, then set this
2264 The default parameter value of '0' causes the kernel
2265 not to attempt recovery of lost locks.
2267 nfsd.nfs4_disable_idmapping=
2268 [NFSv4] When set to the default of '1', the NFSv4
2269 server will return only numeric uids and gids to
2270 clients using auth_sys, and will accept numeric uids
2271 and gids from such clients. This is intended to ease
2272 migration from NFSv2/v3.
2274 objlayoutdriver.osd_login_prog=
2275 [NFS] [OBJLAYOUT] sets the pathname to the program which
2276 is used to automatically discover and login into new
2277 osd-targets. Please see:
2278 Documentation/filesystems/pnfs.txt for more explanations
2280 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
2281 when a NMI is triggered.
2282 Format: [state][,regs][,debounce][,die]
2284 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
2285 Format: [panic,][nopanic,][num]
2287 0 - turn nmi_watchdog off
2288 1 - turn nmi_watchdog on
2289 When panic is specified, panic when an NMI watchdog
2290 timeout occurs (or 'nopanic' to override the opposite
2292 This is useful when you use a panic=... timeout and
2293 need the box quickly up again.
2295 netpoll.carrier_timeout=
2296 [NET] Specifies amount of time (in seconds) that
2297 netpoll should wait for a carrier. By default netpoll
2300 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
2301 emulation library even if a 387 maths coprocessor
2305 [HW] Never suspend the console
2306 Disable suspending of consoles during suspend and
2307 hibernate operations. Once disabled, debugging
2308 messages can reach various consoles while the rest
2309 of the system is being put to sleep (ie, while
2310 debugging driver suspend/resume hooks). This may
2311 not work reliably with all consoles, but is known
2312 to work with serial and VGA consoles.
2313 To facilitate more flexible debugging, we also add
2314 console_suspend, a printk module parameter to control
2315 it. Users could use console_suspend (usually
2316 /sys/module/printk/parameters/console_suspend) to
2317 turn on/off it dynamically.
2319 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
2320 caches in the slab allocator. Saves per-node memory,
2321 but will impact performance.
2325 noapic [SMP,APIC] Tells the kernel to not make use of any
2326 IOAPICs that may be present in the system.
2328 noautogroup Disable scheduler automatic task group creation.
2330 nobats [PPC] Do not use BATs for mapping kernel lowmem
2331 on "Classic" PPC cores.
2335 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
2337 nodelayacct [KNL] Disable per-task delay accounting
2339 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
2341 nodsp [SH] Disable hardware DSP at boot time.
2343 noefi Disable EFI runtime services support.
2348 On X86-32 available only on PAE configured kernels.
2349 noexec=on: enable non-executable mappings (default)
2350 noexec=off: disable non-executable mappings
2353 Disable SMAP (Supervisor Mode Access Prevention)
2354 even if it is supported by processor.
2357 Disable SMEP (Supervisor Mode Execution Prevention)
2358 even if it is supported by processor.
2361 This affects only 32-bit executables.
2362 noexec32=on: enable non-executable mappings (default)
2363 read doesn't imply executable mappings
2364 noexec32=off: disable non-executable mappings
2365 read implies executable mappings
2367 nofpu [MIPS,SH] Disable hardware FPU at boot time.
2369 nofxsr [BUGS=X86-32] Disables x86 floating point extended
2370 register save and restore. The kernel will only save
2371 legacy floating-point registers on task switch.
2373 nohugeiomap [KNL,x86] Disable kernel huge I/O mappings.
2375 noxsave [BUGS=X86] Disables x86 extended register state save
2376 and restore using xsave. The kernel will fallback to
2377 enabling legacy floating-point and sse state.
2379 noxsaveopt [X86] Disables xsaveopt used in saving x86 extended
2380 register states. The kernel will fall back to use
2381 xsave to save the states. By using this parameter,
2382 performance of saving the states is degraded because
2383 xsave doesn't support modified optimization while
2384 xsaveopt supports it on xsaveopt enabled systems.
2386 noxsaves [X86] Disables xsaves and xrstors used in saving and
2387 restoring x86 extended register state in compacted
2388 form of xsave area. The kernel will fall back to use
2389 xsaveopt and xrstor to save and restore the states
2390 in standard form of xsave area. By using this
2391 parameter, xsave area per process might occupy more
2392 memory on xsaves enabled systems.
2394 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
2395 wfi(ARM) instruction doesn't work correctly and not to
2396 use it. This is also useful when using JTAG debugger.
2398 no_file_caps Tells the kernel not to honor file capabilities. The
2399 only way then for a file to be executed with privilege
2400 is to be setuid root or executed by root.
2402 nohalt [IA-64] Tells the kernel not to use the power saving
2403 function PAL_HALT_LIGHT when idle. This increases
2404 power-consumption. On the positive side, it reduces
2405 interrupt wake-up latency, which may improve performance
2406 in certain environments such as networked servers or
2409 nohibernate [HIBERNATION] Disable hibernation and resume.
2411 nohz= [KNL] Boottime enable/disable dynamic ticks
2412 Valid arguments: on, off
2415 nohz_full= [KNL,BOOT]
2416 In kernels built with CONFIG_NO_HZ_FULL=y, set
2417 the specified list of CPUs whose tick will be stopped
2418 whenever possible. The boot CPU will be forced outside
2419 the range to maintain the timekeeping.
2420 The CPUs in this range must also be included in the
2423 noiotrap [SH] Disables trapped I/O port accesses.
2425 noirqdebug [X86-32] Disables the code which attempts to detect and
2426 disable unhandled interrupt sources.
2428 no_timer_check [X86,APIC] Disables the code which tests for
2429 broken timer IRQ sources.
2431 noisapnp [ISAPNP] Disables ISA PnP code.
2433 noinitrd [RAM] Tells the kernel not to load any configured
2436 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
2438 [Deprecated - use intremap=off]
2442 nojitter [IA-64] Disables jitter checking for ITC timers.
2444 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
2446 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
2449 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
2450 steal time is computed, but won't influence scheduler
2453 nolapic [X86-32,APIC] Do not enable or use the local APIC.
2455 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
2457 noltlbs [PPC] Do not use large page/tlb entries for kernel
2458 lowmem mapping on PPC40x.
2460 nomca [IA-64] Disable machine check abort handling
2462 nomce [X86-32] Disable Machine Check Exception
2464 nomfgpt [X86-32] Disable Multi-Function General Purpose
2465 Timer usage (for AMD Geode machines).
2467 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
2468 shutdown the other cpus. Instead use the REBOOT_VECTOR
2471 nomodule Disable module load
2473 nopat [X86] Disable PAT (page attribute table extension of
2474 pagetables) support.
2476 norandmaps Don't use address space randomization. Equivalent to
2477 echo 0 > /proc/sys/kernel/randomize_va_space
2479 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
2481 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
2482 with UP alternatives
2484 nordrand [X86] Disable kernel use of the RDRAND and
2485 RDSEED instructions even if they are supported
2486 by the processor. RDRAND and RDSEED are still
2487 available to user space applications.
2489 noresume [SWSUSP] Disables resume and restores original swap
2492 no-scroll [VGA] Disables scrollback.
2493 This is required for the Braillex ib80-piezo Braille
2494 reader made by F.H. Papenmeier (Germany).
2498 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
2500 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
2501 and disable the IO APIC. legacy for "maxcpus=0".
2503 nosoftlockup [KNL] Disable the soft-lockup detector.
2505 nosync [HW,M68K] Disables sync negotiation for all devices.
2507 notsc [BUGS=X86-32] Disable Time Stamp Counter
2509 nousb [USB] Disable the USB subsystem
2511 nowatchdog [KNL] Disable both lockup detectors, i.e.
2512 soft-lockup and NMI watchdog (hard-lockup).
2516 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
2518 cpu0_hotplug [X86] Turn on CPU0 hotplug feature when
2519 CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off.
2520 Some features depend on CPU0. Known dependencies are:
2521 1. Resume from suspend/hibernate depends on CPU0.
2522 Suspend/hibernate will fail if CPU0 is offline and you
2523 need to online CPU0 before suspend/hibernate.
2524 2. PIC interrupts also depend on CPU0. CPU0 can't be
2525 removed if a PIC interrupt is detected.
2526 It's said poweroff/reboot may depend on CPU0 on some
2527 machines although I haven't seen such issues so far
2528 after CPU0 is offline on a few tested machines.
2529 If the dependencies are under your control, you can
2530 turn on cpu0_hotplug.
2532 nptcg= [IA-64] Override max number of concurrent global TLB
2533 purges which is reported from either PAL_VM_SUMMARY or
2536 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
2537 could support. nr_cpus=n : n >= 1 limits the kernel to
2538 supporting 'n' processors. Later in runtime you can not
2539 use hotplug cpu feature to put more cpu back to online.
2540 just like you compile the kernel NR_CPUS=n
2542 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
2544 numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing.
2545 Allowed values are enable and disable
2547 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
2548 one of ['zone', 'node', 'default'] can be specified
2549 This can be set from sysctl after boot.
2550 See Documentation/sysctl/vm.txt for details.
2552 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
2553 See Documentation/debugging-via-ohci1394.txt for more
2556 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
2557 Rather than timing out after 20 ms if an EC
2558 command is not properly ACKed, override the length
2559 of the timeout. We have interrupts disabled while
2560 waiting for the ACK, so if this is set too high
2561 interrupts *may* be lost!
2563 omap_mux= [OMAP] Override bootloader pin multiplexing.
2564 Format: <mux_mode0.mode_name=value>...
2565 For example, to override I2C bus2:
2566 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
2568 oprofile.timer= [HW]
2569 Use timer interrupt instead of performance counters
2571 oprofile.cpu_type= Force an oprofile cpu type
2572 This might be useful if you have an older oprofile
2573 userland or if you want common events.
2574 Format: { arch_perfmon }
2575 arch_perfmon: [X86] Force use of architectural
2576 perfmon on Intel CPUs instead of the
2577 CPU specific event set.
2578 timer: [X86] Force use of architectural NMI
2579 timer mode (see also oprofile.timer
2580 for generic hr timer mode)
2581 [s390] Force legacy basic mode sampling
2582 (report cpu_type "timer")
2584 oops=panic Always panic on oopses. Default is to just kill the
2585 process, but there is a small probability of
2586 deadlocking the machine.
2587 This will also cause panics on machine check exceptions.
2588 Useful together with panic=30 to trigger a reboot.
2591 See Documentation/sound/oss/oss-parameters.txt
2593 page_owner= [KNL] Boot-time page_owner enabling option.
2594 Storage of the information about who allocated
2595 each page is disabled in default. With this switch,
2597 on: enable the feature
2599 panic= [KNL] Kernel behaviour on panic: delay <timeout>
2600 timeout > 0: seconds before rebooting
2601 timeout = 0: wait forever
2602 timeout < 0: reboot immediately
2605 panic_on_warn panic() instead of WARN(). Useful to cause kdump
2608 crash_kexec_post_notifiers
2609 Run kdump after running panic-notifiers and dumping
2610 kmsg. This only for the users who doubt kdump always
2611 succeeds in any situation.
2612 Note that this also increases risks of kdump failure,
2613 because some panic notifiers can make the crashed
2614 kernel more unstable.
2616 parkbd.port= [HW] Parallel port number the keyboard adapter is
2617 connected to, default is 0.
2619 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
2620 0 for XT, 1 for AT (default is AT).
2623 parport= [HW,PPT] Specify parallel ports. 0 disables.
2624 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
2625 Use 'auto' to force the driver to use any
2626 IRQ/DMA settings detected (the default is to
2627 ignore detected IRQ/DMA settings because of
2628 possible conflicts). You can specify the base
2629 address, IRQ, and DMA settings; IRQ and DMA
2630 should be numbers, or 'auto' (for using detected
2631 settings on that particular port), or 'nofifo'
2632 (to avoid using a FIFO even if it is detected).
2633 Parallel ports are assigned in the order they
2634 are specified on the command line, starting
2637 parport_init_mode= [HW,PPT]
2638 Configure VIA parallel port to operate in
2639 a specific mode. This is necessary on Pegasos
2640 computer where firmware has no options for setting
2641 up parallel port mode and sets it to spp.
2642 Currently this function knows 686a and 8231 chips.
2643 Format: [spp|ps2|epp|ecp|ecpepp]
2646 Halt all CPUs after the first oops has been printed for
2647 the specified number of seconds. This is to be used if
2648 your oopses keep scrolling off the screen.
2653 See header of drivers/block/paride/pcd.c.
2654 See also Documentation/blockdev/paride.txt.
2656 pci=option[,option...] [PCI] various PCI subsystem options:
2657 earlydump [X86] dump PCI config space before the kernel
2659 off [X86] don't probe for the PCI bus
2660 bios [X86-32] force use of PCI BIOS, don't access
2661 the hardware directly. Use this if your machine
2662 has a non-standard PCI host bridge.
2663 nobios [X86-32] disallow use of PCI BIOS, only direct
2664 hardware access methods are allowed. Use this
2665 if you experience crashes upon bootup and you
2666 suspect they are caused by the BIOS.
2667 conf1 [X86] Force use of PCI Configuration
2669 conf2 [X86] Force use of PCI Configuration
2671 noaer [PCIE] If the PCIEAER kernel config parameter is
2672 enabled, this kernel boot option can be used to
2673 disable the use of PCIE advanced error reporting.
2674 nodomains [PCI] Disable support for multiple PCI
2675 root domains (aka PCI segments, in ACPI-speak).
2676 nommconf [X86] Disable use of MMCONFIG for PCI
2678 check_enable_amd_mmconf [X86] check for and enable
2679 properly configured MMIO access to PCI
2680 config space on AMD family 10h CPU
2681 nomsi [MSI] If the PCI_MSI kernel config parameter is
2682 enabled, this kernel boot option can be used to
2683 disable the use of MSI interrupts system-wide.
2684 noioapicquirk [APIC] Disable all boot interrupt quirks.
2685 Safety option to keep boot IRQs enabled. This
2686 should never be necessary.
2687 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2688 primary IO-APIC for bridges that cannot disable
2689 boot IRQs. This fixes a source of spurious IRQs
2690 when the system masks IRQs.
2691 noioapicreroute [APIC] Disable workaround that uses the
2692 boot IRQ equivalent of an IRQ that connects to
2693 a chipset where boot IRQs cannot be disabled.
2694 The opposite of ioapicreroute.
2695 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2696 routing table. These calls are known to be buggy
2697 on several machines and they hang the machine
2698 when used, but on other computers it's the only
2699 way to get the interrupt routing table. Try
2700 this option if the kernel is unable to allocate
2701 IRQs or discover secondary PCI buses on your
2703 rom [X86] Assign address space to expansion ROMs.
2704 Use with caution as certain devices share
2705 address decoders between ROMs and other
2707 norom [X86] Do not assign address space to
2708 expansion ROMs that do not already have
2709 BIOS assigned address ranges.
2710 nobar [X86] Do not assign address space to the
2711 BARs that weren't assigned by the BIOS.
2712 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2713 assigned automatically to PCI devices. You can
2714 make the kernel exclude IRQs of your ISA cards
2716 pirqaddr=0xAAAAA [X86] Specify the physical address
2717 of the PIRQ table (normally generated
2718 by the BIOS) if it is outside the
2719 F0000h-100000h range.
2720 lastbus=N [X86] Scan all buses thru bus #N. Can be
2721 useful if the kernel is unable to find your
2722 secondary buses and you want to tell it
2723 explicitly which ones they are.
2724 assign-busses [X86] Always assign all PCI bus
2725 numbers ourselves, overriding
2726 whatever the firmware may have done.
2727 usepirqmask [X86] Honor the possible IRQ mask stored
2728 in the BIOS $PIR table. This is needed on
2729 some systems with broken BIOSes, notably
2730 some HP Pavilion N5400 and Omnibook XE3
2731 notebooks. This will have no effect if ACPI
2732 IRQ routing is enabled.
2733 noacpi [X86] Do not use ACPI for IRQ routing
2734 or for PCI scanning.
2735 use_crs [X86] Use PCI host bridge window information
2736 from ACPI. On BIOSes from 2008 or later, this
2737 is enabled by default. If you need to use this,
2738 please report a bug.
2739 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2740 If you need to use this, please report a bug.
2741 routeirq Do IRQ routing for all PCI devices.
2742 This is normally done in pci_enable_device(),
2743 so this option is a temporary workaround
2744 for broken drivers that don't call it.
2745 skip_isa_align [X86] do not align io start addr, so can
2746 handle more pci cards
2747 firmware [ARM] Do not re-enumerate the bus but instead
2748 just use the configuration from the
2749 bootloader. This is currently used on
2750 IXP2000 systems where the bus has to be
2751 configured a certain way for adjunct CPUs.
2752 noearly [X86] Don't do any early type 1 scanning.
2753 This might help on some broken boards which
2754 machine check when some devices' config space
2755 is read. But various workarounds are disabled
2756 and some IOMMU drivers will not work.
2757 bfsort Sort PCI devices into breadth-first order.
2758 This sorting is done to get a device
2759 order compatible with older (<= 2.4) kernels.
2760 nobfsort Don't sort PCI devices into breadth-first order.
2761 pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
2762 tuning and use the BIOS-configured MPS defaults.
2763 pcie_bus_safe Set every device's MPS to the largest value
2764 supported by all devices below the root complex.
2765 pcie_bus_perf Set device MPS to the largest allowable MPS
2766 based on its parent bus. Also set MRRS (Max
2767 Read Request Size) to the largest supported
2768 value (no larger than the MPS that the device
2769 or bus can support) for best performance.
2770 pcie_bus_peer2peer Set every device's MPS to 128B, which
2771 every device is guaranteed to support. This
2772 configuration allows peer-to-peer DMA between
2773 any pair of devices, possibly at the cost of
2774 reduced performance. This also guarantees
2775 that hot-added devices will work.
2776 cbiosize=nn[KMG] The fixed amount of bus space which is
2777 reserved for the CardBus bridge's IO window.
2778 The default value is 256 bytes.
2779 cbmemsize=nn[KMG] The fixed amount of bus space which is
2780 reserved for the CardBus bridge's memory
2781 window. The default value is 64 megabytes.
2784 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2785 Specifies alignment and device to reassign
2786 aligned memory resources.
2787 If <order of align> is not specified,
2788 PAGE_SIZE is used as alignment.
2789 PCI-PCI bridge can be specified, if resource
2790 windows need to be expanded.
2791 ecrc= Enable/disable PCIe ECRC (transaction layer
2792 end-to-end CRC checking).
2793 bios: Use BIOS/firmware settings. This is the
2797 hpiosize=nn[KMG] The fixed amount of bus space which is
2798 reserved for hotplug bridge's IO window.
2799 Default size is 256 bytes.
2800 hpmemsize=nn[KMG] The fixed amount of bus space which is
2801 reserved for hotplug bridge's memory window.
2802 Default size is 2 megabytes.
2803 realloc= Enable/disable reallocating PCI bridge resources
2804 if allocations done by BIOS are too small to
2805 accommodate resources required by all child
2807 off: Turn realloc off
2809 realloc same as realloc=on
2810 noari do not use PCIe ARI.
2811 pcie_scan_all Scan all possible PCIe devices. Otherwise we
2812 only look for one device below a PCIe downstream
2815 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2818 force Enable ASPM even on devices that claim not to support it.
2819 WARNING: Forcing ASPM on may cause system lockups.
2821 pcie_hp= [PCIE] PCI Express Hotplug driver options:
2822 nomsi Do not use MSI for PCI Express Native Hotplug (this
2823 makes all PCIe ports use INTx for hotplug services).
2825 pcie_ports= [PCIE] PCIe ports handling:
2826 auto Ask the BIOS whether or not to use native PCIe services
2827 associated with PCIe ports (PME, hot-plug, AER). Use
2828 them only if that is allowed by the BIOS.
2829 native Use native PCIe services associated with PCIe ports
2831 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2834 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2835 nomsi Do not use MSI for native PCIe PME signaling (this makes
2836 all PCIe root ports use INTx for all services).
2838 pcmv= [HW,PCMCIA] BadgePAD 4
2842 Keep all power-domains already enabled by bootloader on,
2843 even if no driver has claimed them. This is useful
2844 for debug and development, but should not be
2845 needed on a platform with proper driver support.
2848 See Documentation/blockdev/paride.txt.
2850 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2853 See arch/parisc/kernel/pdc_chassis.c
2855 percpu_alloc= Select which percpu first chunk allocator to use.
2856 Currently supported values are "embed" and "page".
2857 Archs may support subset or none of the selections.
2858 See comments in mm/percpu.c for details on each
2859 allocator. This parameter is primarily for debugging
2860 and performance comparison.
2863 See Documentation/blockdev/paride.txt.
2866 See Documentation/blockdev/paride.txt.
2868 pirq= [SMP,APIC] Manual mp-table setup
2869 See Documentation/x86/i386/IO-APIC.txt.
2871 plip= [PPT,NET] Parallel port network link
2872 Format: { parport<nr> | timid | 0 }
2873 See also Documentation/parport.txt.
2875 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2876 Override pmtimer IOPort with a hex value.
2880 Enable PNP debug messages (depends on the
2881 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2882 via /sys/module/pnp/parameters/debug. We always show
2883 current resource usage; turning this on also shows
2884 possible settings and some assignment information.
2890 { on | off | curr | res | no-curr | no-res }
2893 [ISAPNP] Exclude IRQs for the autoconfiguration
2896 [ISAPNP] Exclude DMAs for the autoconfiguration
2898 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2899 Ranges are in pairs (I/O port base and size).
2902 [ISAPNP] Exclude memory regions for the
2904 Ranges are in pairs (memory base and size).
2906 ports= [IP_VS_FTP] IPVS ftp helper module
2908 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2910 Format: <port>,<port>....
2912 print-fatal-signals=
2913 [KNL] debug: print fatal signals
2915 If enabled, warn about various signal handling
2916 related application anomalies: too many signals,
2917 too many POSIX.1 timers, fatal signals causing a
2920 If you hit the warning due to signal overflow,
2921 you might want to try "ulimit -i unlimited".
2925 printk.always_kmsg_dump=
2926 Trigger kmsg_dump for cases other than kernel oops or
2928 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2931 printk.time= Show timing data prefixed to each printk message line
2932 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2934 processor.max_cstate= [HW,ACPI]
2935 Limit processor to maximum C-state
2936 max_cstate=9 overrides any DMI blacklist limit.
2938 processor.nocst [HW,ACPI]
2939 Ignore the _CST method to determine C-states,
2940 instead using the legacy FADT method
2942 profile= [KNL] Enable kernel profiling via /proc/profile
2943 Format: [schedule,]<number>
2944 Param: "schedule" - profile schedule points.
2945 Param: <number> - step/bucket size as a power of 2 for
2946 statistical time based profiling.
2947 Param: "sleep" - profile D-state sleeping (millisecs).
2948 Requires CONFIG_SCHEDSTATS
2949 Param: "kvm" - profile VM exits.
2951 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2953 See Documentation/blockdev/ramdisk.txt.
2955 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2956 probe for; one of (bare|imps|exps|lifebook|any).
2957 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2959 psmouse.resetafter= [HW,MOUSE]
2960 Try to reset the device after so many bad packets
2963 [HW,MOUSE] Set desired mouse resolution, in dpi.
2964 psmouse.smartscroll=
2965 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2966 0 = disabled, 1 = enabled (default).
2968 pstore.backend= Specify the name of the pstore backend to use
2971 See Documentation/blockdev/paride.txt.
2974 [KNL] Number of legacy pty's. Overwrites compiled-in
2977 quiet [KNL] Disable most log messages
2982 See Documentation/md.txt.
2984 ramdisk_blocksize= [RAM]
2985 See Documentation/blockdev/ramdisk.txt.
2987 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2988 See Documentation/blockdev/ramdisk.txt.
2991 In kernels built with CONFIG_RCU_NOCB_CPU=y, set
2992 the specified list of CPUs to be no-callback CPUs.
2993 Invocation of these CPUs' RCU callbacks will
2994 be offloaded to "rcuox/N" kthreads created for
2995 that purpose, where "x" is "b" for RCU-bh, "p"
2996 for RCU-preempt, and "s" for RCU-sched, and "N"
2997 is the CPU number. This reduces OS jitter on the
2998 offloaded CPUs, which can be useful for HPC and
2999 real-time workloads. It can also improve energy
3000 efficiency for asymmetric multiprocessors.
3003 Rather than requiring that offloaded CPUs
3004 (specified by rcu_nocbs= above) explicitly
3005 awaken the corresponding "rcuoN" kthreads,
3006 make these kthreads poll for callbacks.
3007 This improves the real-time response for the
3008 offloaded CPUs by relieving them of the need to
3009 wake up the corresponding kthread, but degrades
3010 energy efficiency by requiring that the kthreads
3011 periodically wake up to do the polling.
3013 rcutree.blimit= [KNL]
3014 Set maximum number of finished RCU callbacks to
3015 process in one batch.
3017 rcutree.dump_tree= [KNL]
3018 Dump the structure of the rcu_node combining tree
3019 out at early boot. This is used for diagnostic
3020 purposes, to verify correct tree setup.
3022 rcutree.gp_cleanup_delay= [KNL]
3023 Set the number of jiffies to delay each step of
3024 RCU grace-period cleanup. This only has effect
3025 when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set.
3027 rcutree.gp_init_delay= [KNL]
3028 Set the number of jiffies to delay each step of
3029 RCU grace-period initialization. This only has
3030 effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT
3033 rcutree.gp_preinit_delay= [KNL]
3034 Set the number of jiffies to delay each step of
3035 RCU grace-period pre-initialization, that is,
3036 the propagation of recent CPU-hotplug changes up
3037 the rcu_node combining tree. This only has effect
3038 when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set.
3040 rcutree.rcu_fanout_exact= [KNL]
3041 Disable autobalancing of the rcu_node combining
3042 tree. This is used by rcutorture, and might
3043 possibly be useful for architectures having high
3044 cache-to-cache transfer latencies.
3046 rcutree.rcu_fanout_leaf= [KNL]
3047 Increase the number of CPUs assigned to each
3048 leaf rcu_node structure. Useful for very large
3051 rcutree.jiffies_till_sched_qs= [KNL]
3052 Set required age in jiffies for a
3053 given grace period before RCU starts
3054 soliciting quiescent-state help from
3055 rcu_note_context_switch().
3057 rcutree.jiffies_till_first_fqs= [KNL]
3058 Set delay from grace-period initialization to
3059 first attempt to force quiescent states.
3060 Units are jiffies, minimum value is zero,
3061 and maximum value is HZ.
3063 rcutree.jiffies_till_next_fqs= [KNL]
3064 Set delay between subsequent attempts to force
3065 quiescent states. Units are jiffies, minimum
3066 value is one, and maximum value is HZ.
3068 rcutree.kthread_prio= [KNL,BOOT]
3069 Set the SCHED_FIFO priority of the RCU per-CPU
3070 kthreads (rcuc/N). This value is also used for
3071 the priority of the RCU boost threads (rcub/N)
3072 and for the RCU grace-period kthreads (rcu_bh,
3073 rcu_preempt, and rcu_sched). If RCU_BOOST is
3074 set, valid values are 1-99 and the default is 1
3075 (the least-favored priority). Otherwise, when
3076 RCU_BOOST is not set, valid values are 0-99 and
3077 the default is zero (non-realtime operation).
3079 rcutree.rcu_nocb_leader_stride= [KNL]
3080 Set the number of NOCB kthread groups, which
3081 defaults to the square root of the number of
3082 CPUs. Larger numbers reduces the wakeup overhead
3083 on the per-CPU grace-period kthreads, but increases
3084 that same overhead on each group's leader.
3086 rcutree.qhimark= [KNL]
3087 Set threshold of queued RCU callbacks beyond which
3088 batch limiting is disabled.
3090 rcutree.qlowmark= [KNL]
3091 Set threshold of queued RCU callbacks below which
3092 batch limiting is re-enabled.
3094 rcutree.rcu_idle_gp_delay= [KNL]
3095 Set wakeup interval for idle CPUs that have
3096 RCU callbacks (RCU_FAST_NO_HZ=y).
3098 rcutree.rcu_idle_lazy_gp_delay= [KNL]
3099 Set wakeup interval for idle CPUs that have
3100 only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y).
3101 Lazy RCU callbacks are those which RCU can
3102 prove do nothing more than free memory.
3104 rcutorture.cbflood_inter_holdoff= [KNL]
3105 Set holdoff time (jiffies) between successive
3106 callback-flood tests.
3108 rcutorture.cbflood_intra_holdoff= [KNL]
3109 Set holdoff time (jiffies) between successive
3110 bursts of callbacks within a given callback-flood
3113 rcutorture.cbflood_n_burst= [KNL]
3114 Set the number of bursts making up a given
3115 callback-flood test. Set this to zero to
3116 disable callback-flood testing.
3118 rcutorture.cbflood_n_per_burst= [KNL]
3119 Set the number of callbacks to be registered
3120 in a given burst of a callback-flood test.
3122 rcutorture.fqs_duration= [KNL]
3123 Set duration of force_quiescent_state bursts.
3125 rcutorture.fqs_holdoff= [KNL]
3126 Set holdoff time within force_quiescent_state bursts.
3128 rcutorture.fqs_stutter= [KNL]
3129 Set wait time between force_quiescent_state bursts.
3131 rcutorture.gp_exp= [KNL]
3132 Use expedited update-side primitives.
3134 rcutorture.gp_normal= [KNL]
3135 Use normal (non-expedited) update-side primitives.
3136 If both gp_exp and gp_normal are set, do both.
3137 If neither gp_exp nor gp_normal are set, still
3140 rcutorture.n_barrier_cbs= [KNL]
3141 Set callbacks/threads for rcu_barrier() testing.
3143 rcutorture.nfakewriters= [KNL]
3144 Set number of concurrent RCU writers. These just
3145 stress RCU, they don't participate in the actual
3146 test, hence the "fake".
3148 rcutorture.nreaders= [KNL]
3149 Set number of RCU readers. The value -1 selects
3150 N-1, where N is the number of CPUs. A value
3151 "n" less than -1 selects N-n-2, where N is again
3152 the number of CPUs. For example, -2 selects N
3153 (the number of CPUs), -3 selects N+1, and so on.
3155 rcutorture.object_debug= [KNL]
3156 Enable debug-object double-call_rcu() testing.
3158 rcutorture.onoff_holdoff= [KNL]
3159 Set time (s) after boot for CPU-hotplug testing.
3161 rcutorture.onoff_interval= [KNL]
3162 Set time (s) between CPU-hotplug operations, or
3163 zero to disable CPU-hotplug testing.
3165 rcutorture.torture_runnable= [BOOT]
3166 Start rcutorture running at boot time.
3168 rcutorture.shuffle_interval= [KNL]
3169 Set task-shuffle interval (s). Shuffling tasks
3170 allows some CPUs to go into dyntick-idle mode
3171 during the rcutorture test.
3173 rcutorture.shutdown_secs= [KNL]
3174 Set time (s) after boot system shutdown. This
3175 is useful for hands-off automated testing.
3177 rcutorture.stall_cpu= [KNL]
3178 Duration of CPU stall (s) to test RCU CPU stall
3179 warnings, zero to disable.
3181 rcutorture.stall_cpu_holdoff= [KNL]
3182 Time to wait (s) after boot before inducing stall.
3184 rcutorture.stat_interval= [KNL]
3185 Time (s) between statistics printk()s.
3187 rcutorture.stutter= [KNL]
3188 Time (s) to stutter testing, for example, specifying
3189 five seconds causes the test to run for five seconds,
3190 wait for five seconds, and so on. This tests RCU's
3191 ability to transition abruptly to and from idle.
3193 rcutorture.test_boost= [KNL]
3194 Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
3195 "Maybe" means test if the RCU implementation
3196 under test support RCU priority boosting.
3198 rcutorture.test_boost_duration= [KNL]
3199 Duration (s) of each individual boost test.
3201 rcutorture.test_boost_interval= [KNL]
3202 Interval (s) between each boost test.
3204 rcutorture.test_no_idle_hz= [KNL]
3205 Test RCU's dyntick-idle handling. See also the
3206 rcutorture.shuffle_interval parameter.
3208 rcutorture.torture_type= [KNL]
3209 Specify the RCU implementation to test.
3211 rcutorture.verbose= [KNL]
3212 Enable additional printk() statements.
3214 rcupdate.rcu_expedited= [KNL]
3215 Use expedited grace-period primitives, for
3216 example, synchronize_rcu_expedited() instead
3217 of synchronize_rcu(). This reduces latency,
3218 but can increase CPU utilization, degrade
3219 real-time latency, and degrade energy efficiency.
3221 rcupdate.rcu_cpu_stall_suppress= [KNL]
3222 Suppress RCU CPU stall warning messages.
3224 rcupdate.rcu_cpu_stall_timeout= [KNL]
3225 Set timeout for RCU CPU stall warning messages.
3227 rcupdate.rcu_task_stall_timeout= [KNL]
3228 Set timeout in jiffies for RCU task stall warning
3229 messages. Disable with a value less than or equal
3232 rcupdate.rcu_self_test= [KNL]
3233 Run the RCU early boot self tests
3235 rcupdate.rcu_self_test_bh= [KNL]
3236 Run the RCU bh early boot self tests
3238 rcupdate.rcu_self_test_sched= [KNL]
3239 Run the RCU sched early boot self tests
3243 Run specified binary instead of /init from the ramdisk,
3244 used for early userspace startup. See initrd.
3247 Format (x86 or x86_64):
3248 [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \
3250 [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
3252 Where reboot_mode is one of warm (soft) or cold (hard) or gpio,
3253 reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
3254 reboot_force is either force or not specified,
3255 reboot_cpu is s[mp]#### with #### being the processor
3256 to be used for rebooting.
3259 [KNL, SMP] Set scheduler's default relax_domain_level.
3260 See Documentation/cgroups/cpusets.txt.
3262 relative_sleep_states=
3263 [SUSPEND] Use sleep state labeling where the deepest
3264 state available other than hibernation is always "mem".
3265 Format: { "0" | "1" }
3266 0 -- Traditional sleep state labels.
3267 1 -- Relative sleep state labels.
3269 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
3271 reservetop= [X86-32]
3273 Reserves a hole at the top of the kernel virtual
3278 Set the amount of memory to reserve for BIOS at
3279 the bottom of the address space.
3281 reset_devices [KNL] Force drivers to reset the underlying device
3282 during initialization.
3285 Specify the partition device for software suspend
3287 {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
3289 resume_offset= [SWSUSP]
3290 Specify the offset from the beginning of the partition
3291 given by "resume=" at which the swap header is located,
3292 in <PAGE_SIZE> units (needed only for swap files).
3293 See Documentation/power/swsusp-and-swap-files.txt
3295 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
3296 read the resume files
3298 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
3299 Useful for devices that are detected asynchronously
3300 (e.g. USB and MMC devices).
3302 hibernate= [HIBERNATION]
3303 noresume Don't check if there's a hibernation image
3304 present during boot.
3305 nocompress Don't compress/decompress hibernation images.
3306 no Disable hibernation and resume.
3308 retain_initrd [RAM] Keep initrd memory after extraction
3310 rfkill.default_state=
3311 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm,
3312 etc. communication is blocked by default.
3315 rfkill.master_switch_mode=
3316 0 The "airplane mode" button does nothing.
3317 1 The "airplane mode" button toggles between everything
3318 blocked and the previous configuration.
3319 2 The "airplane mode" button toggles between everything
3320 blocked and everything unblocked.
3322 rhash_entries= [KNL,NET]
3323 Set number of hash buckets for route cache
3325 ro [KNL] Mount root device read-only on boot
3327 root= [KNL] Root filesystem
3328 See name_to_dev_t comment in init/do_mounts.c.
3330 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
3331 mount the root filesystem
3333 rootflags= [KNL] Set root filesystem mount option string
3335 rootfstype= [KNL] Set root filesystem type
3337 rootwait [KNL] Wait (indefinitely) for root device to show up.
3338 Useful for devices that are detected asynchronously
3339 (e.g. USB and MMC devices).
3341 rproc_mem=nn[KMG][@address]
3342 [KNL,ARM,CMA] Remoteproc physical memory block.
3343 Memory area to be used by remote processor image,
3346 rw [KNL] Mount root device read-write on boot
3348 S [KNL] Run init in single mode
3350 s390_iommu= [HW,S390]
3351 Set s390 IOTLB flushing mode
3353 With strict flushing every unmap operation will result in
3354 an IOTLB flush. Default is lazy flushing before reuse,
3358 See drivers/net/irda/sa1100_ir.c.
3360 sbni= [NET] Granch SBNI12 leased line adapter
3362 sched_debug [KNL] Enables verbose scheduler debug messages.
3364 skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
3365 xtime_lock contention on larger systems, and/or RCU lock
3366 contention on all systems with CONFIG_MAXSMP set.
3367 Format: { "0" | "1" }
3368 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
3370 Note: increases power consumption, thus should only be
3371 enabled if running jitter sensitive (HPC/RT) workloads.
3373 security= [SECURITY] Choose a security module to enable at boot.
3374 If this boot parameter is not specified, only the first
3375 security module asking for security registration will be
3376 loaded. An invalid security module name will be treated
3377 as if no module has been chosen.
3379 selinux= [SELINUX] Disable or enable SELinux at boot time.
3380 Format: { "0" | "1" }
3381 See security/selinux/Kconfig help text.
3384 Default value is set via kernel config option.
3385 If enabled at boot time, /selinux/disable can be used
3386 later to disable prior to initial policy load.
3388 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
3389 Format: { "0" | "1" }
3390 See security/apparmor/Kconfig help text
3393 Default value is set via kernel config option.
3395 serialnumber [BUGS=X86-32]
3398 Maximal number of shapers.
3400 show_msr= [x86] show boot-time MSR settings
3401 Format: { <integer> }
3402 Show boot-time (BIOS-initialized) MSR settings.
3403 The parameter means the number of CPUs to show,
3404 for example 1 means boot CPU only.
3412 Disable merging of slabs with similar size. May be
3413 necessary if there is some reason to distinguish
3414 allocs to different slabs. Debug options disable
3415 merging on their own.
3416 For more information see Documentation/vm/slub.txt.
3418 slab_max_order= [MM, SLAB]
3419 Determines the maximum allowed order for slabs.
3420 A high setting may cause OOMs due to memory
3421 fragmentation. Defaults to 1 for systems with
3422 more than 32MB of RAM, 0 otherwise.
3424 slub_debug[=options[,slabs]] [MM, SLUB]
3425 Enabling slub_debug allows one to determine the
3426 culprit if slab objects become corrupted. Enabling
3427 slub_debug can create guard zones around objects and
3428 may poison objects when not in use. Also tracks the
3429 last alloc / free. For more information see
3430 Documentation/vm/slub.txt.
3432 slub_max_order= [MM, SLUB]
3433 Determines the maximum allowed order for slabs.
3434 A high setting may cause OOMs due to memory
3435 fragmentation. For more information see
3436 Documentation/vm/slub.txt.
3438 slub_min_objects= [MM, SLUB]
3439 The minimum number of objects per slab. SLUB will
3440 increase the slab order up to slub_max_order to
3441 generate a sufficiently large slab able to contain
3442 the number of objects indicated. The higher the number
3443 of objects the smaller the overhead of tracking slabs
3444 and the less frequently locks need to be acquired.
3445 For more information see Documentation/vm/slub.txt.
3447 slub_min_order= [MM, SLUB]
3448 Determines the minimum page order for slabs. Must be
3449 lower than slub_max_order.
3450 For more information see Documentation/vm/slub.txt.
3452 slub_nomerge [MM, SLUB]
3453 Same with slab_nomerge. This is supported for legacy.
3454 See slab_nomerge for more information.
3457 Format: <io1>[,<io2>[,...,<io8>]]
3459 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
3460 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
3461 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
3462 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
3463 smsc-ircc2.ircc_irq= [HW] IRQ line
3464 smsc-ircc2.ircc_dma= [HW] DMA channel
3465 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
3466 0: Toshiba Satellite 1800 (GP data pin select)
3467 1: Fast pin select (default)
3471 [KNL] Should the soft-lockup detector generate panics.
3474 softlockup_all_cpu_backtrace=
3475 [KNL] Should the soft-lockup detector generate
3476 backtraces on all cpus.
3479 sonypi.*= [HW] Sony Programmable I/O Control Device driver
3480 See Documentation/laptops/sonypi.txt
3482 spia_io_base= [HW,MTD]
3488 Enabled the stack tracer on boot up.
3490 stacktrace_filter=[function-list]
3491 [FTRACE] Limit the functions that the stack tracer
3492 will trace at boot up. function-list is a comma separated
3493 list of functions. This list can be changed at run
3494 time by the stack_trace_filter file in the debugfs
3495 tracing directory. Note, this enables stack tracing
3496 and the stacktrace above is not needed.
3500 Set the STI (builtin display/keyboard on the HP-PARISC
3501 machines) console (graphic card) which should be used
3502 as the initial boot-console.
3503 See also comment in drivers/video/console/sticore.c.
3506 See comment in drivers/video/console/sticore.c.
3509 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
3511 sunrpc.min_resvport=
3512 sunrpc.max_resvport=
3514 SunRPC servers often require that client requests
3515 originate from a privileged port (i.e. a port in the
3516 range 0 < portnr < 1024).
3517 An administrator who wishes to reserve some of these
3518 ports for other uses may adjust the range that the
3519 kernel's sunrpc client considers to be privileged
3520 using these two parameters to set the minimum and
3521 maximum port values.
3525 Control how the NFS server code allocates CPUs to
3526 service thread pools. Depending on how many NICs
3527 you have and where their interrupts are bound, this
3528 option will affect which CPUs will do NFS serving.
3529 Note: this parameter cannot be changed while the
3530 NFS server is running.
3532 auto the server chooses an appropriate mode
3533 automatically using heuristics
3534 global a single global pool contains all CPUs
3535 percpu one pool for each CPU
3536 pernode one pool for each NUMA node (equivalent
3537 to global on non-NUMA machines)
3539 sunrpc.tcp_slot_table_entries=
3540 sunrpc.udp_slot_table_entries=
3542 Sets the upper limit on the number of simultaneous
3543 RPC calls that can be sent from the client to a
3544 server. Increasing these values may allow you to
3545 improve throughput, but will also increase the
3546 amount of memory reserved for use by the client.
3548 suspend.pm_test_delay=
3550 Sets the number of seconds to remain in a suspend test
3551 mode before resuming the system (see
3552 /sys/power/pm_test). Only available when CONFIG_PM_DEBUG
3553 is set. Default value is 5.
3556 [KNL] Enable accounting of swap in memory resource
3557 controller if no parameter or 1 is given or disable
3558 it if 0 is given (See Documentation/cgroups/memory.txt)
3560 swiotlb= [ARM,IA-64,PPC,MIPS,X86]
3561 Format: { <int> | force }
3562 <int> -- Number of I/O TLB slabs
3563 force -- force using of bounce buffers even if they
3564 wouldn't be automatically used by the kernel
3568 sysfs.deprecated=0|1 [KNL]
3569 Enable/disable old style sysfs layout for old udev
3570 on older distributions. When this option is enabled
3571 very new udev will not work anymore. When this option
3572 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
3573 in older udev will not work anymore.
3574 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
3575 the kernel configuration.
3577 sysrq_always_enabled
3579 Ignore sysrq setting - this boot parameter will
3580 neutralize any effect of /proc/sys/kernel/sysrq.
3581 Useful for debugging.
3583 tcpmhash_entries= [KNL,NET]
3584 Set the number of tcp_metrics_hash slots.
3585 Default value is 8192 or 16384 depending on total
3586 ram pages. This is used to specify the TCP metrics
3587 cache size. See Documentation/networking/ip-sysctl.txt
3588 "tcp_no_metrics_save" section for more details.
3592 test_suspend= [SUSPEND][,N]
3593 Specify "mem" (for Suspend-to-RAM) or "standby" (for
3594 standby suspend) or "freeze" (for suspend type freeze)
3595 as the system sleep state during system startup with
3596 the optional capability to repeat N number of times.
3597 The system is woken from this state using a
3598 wakeup-capable RTC alarm.
3600 thash_entries= [KNL,NET]
3601 Set number of hash buckets for TCP connection
3603 thermal.act= [HW,ACPI]
3604 -1: disable all active trip points in all thermal zones
3605 <degrees C>: override all lowest active trip points
3607 thermal.crt= [HW,ACPI]
3608 -1: disable all critical trip points in all thermal zones
3609 <degrees C>: override all critical trip points
3611 thermal.nocrt= [HW,ACPI]
3612 Set to disable actions on ACPI thermal zone
3613 critical and hot trip points.
3615 thermal.off= [HW,ACPI]
3616 1: disable ACPI thermal control
3618 thermal.psv= [HW,ACPI]
3619 -1: disable all passive trip points
3620 <degrees C>: override all passive trip points to this
3623 thermal.tzp= [HW,ACPI]
3624 Specify global default ACPI thermal zone polling rate
3625 <deci-seconds>: poll all this frequency
3626 0: no polling (default)
3629 Force threading of all interrupt handlers except those
3630 marked explicitly IRQF_NO_THREAD.
3633 Enable the Transcendent memory driver if built-in.
3635 tmem.cleancache=0|1 [KNL, XEN]
3636 Default is on (1). Disable the usage of the cleancache
3637 API to send anonymous pages to the hypervisor.
3639 tmem.frontswap=0|1 [KNL, XEN]
3640 Default is on (1). Disable the usage of the frontswap
3641 API to send swap pages to the hypervisor. If disabled
3642 the selfballooning and selfshrinking are force disabled.
3644 tmem.selfballooning=0|1 [KNL, XEN]
3645 Default is on (1). Disable the driving of swap pages
3648 tmem.selfshrinking=0|1 [KNL, XEN]
3649 Default is on (1). Partial swapoff that immediately
3650 transfers pages from Xen hypervisor back to the
3651 kernel based on different criteria.
3655 Specify if the kernel should make use of the cpu
3656 topology information if the hardware supports this.
3657 The scheduler will make use of this information and
3658 e.g. base its process migration decisions on it.
3661 topology_updates= [KNL, PPC, NUMA]
3663 Specify if the kernel should ignore (off)
3664 topology updates sent by the hypervisor to this
3669 tpm_suspend_pcr=[HW,TPM]
3670 Format: integer pcr id
3671 Specify that at suspend time, the tpm driver
3672 should extend the specified pcr with zeros,
3673 as a workaround for some chips which fail to
3674 flush the last written pcr on TPM_SaveState.
3675 This will guarantee that all the other pcrs
3678 trace_buf_size=nn[KMG]
3679 [FTRACE] will set tracing buffer size on each cpu.
3681 trace_event=[event-list]
3682 [FTRACE] Set and start specified trace events in order
3683 to facilitate early boot debugging.
3684 See also Documentation/trace/events.txt
3686 trace_options=[option-list]
3687 [FTRACE] Enable or disable tracer options at boot.
3688 The option-list is a comma delimited list of options
3689 that can be enabled or disabled just as if you were
3690 to echo the option name into
3692 /sys/kernel/debug/tracing/trace_options
3694 For example, to enable stacktrace option (to dump the
3695 stack trace of each event), add to the command line:
3697 trace_options=stacktrace
3699 See also Documentation/trace/ftrace.txt "trace options"
3703 Have the tracepoints sent to printk as well as the
3704 tracing ring buffer. This is useful for early boot up
3705 where the system hangs or reboots and does not give the
3706 option for reading the tracing buffer or performing a
3707 ftrace_dump_on_oops.
3709 To turn off having tracepoints sent to printk,
3710 echo 0 > /proc/sys/kernel/tracepoint_printk
3711 Note, echoing 1 into this file without the
3712 tracepoint_printk kernel cmdline option has no effect.
3716 Having tracepoints sent to printk() and activating high
3717 frequency tracepoints such as irq or sched, can cause
3718 the system to live lock.
3721 [FTRACE] enable this option to disable tracing when a
3722 warning is hit. This turns off "tracing_on". Tracing can
3723 be enabled again by echoing '1' into the "tracing_on"
3724 file located in /sys/kernel/debug/tracing/
3726 This option is useful, as it disables the trace before
3727 the WARNING dump is called, which prevents the trace to
3728 be filled with content caused by the warning output.
3730 This option can also be set at run time via the sysctl
3731 option: kernel/traceoff_on_warning
3733 transparent_hugepage=
3735 Format: [always|madvise|never]
3736 Can be used to control the default behavior of the system
3737 with respect to transparent hugepages.
3738 See Documentation/vm/transhuge.txt for more details.
3740 tsc= Disable clocksource stability checks for TSC.
3742 [x86] reliable: mark tsc clocksource as reliable, this
3743 disables clocksource verification at runtime, as well
3744 as the stability checks done at bootup. Used to enable
3745 high-resolution timer mode on older hardware, and in
3746 virtualized environment.
3747 [x86] noirqtime: Do not use TSC to do irq accounting.
3748 Used to run time disable IRQ_TIME_ACCOUNTING on any
3749 platforms where RDTSC is slow and this accounting
3752 turbografx.map[2|3]= [HW,JOY]
3753 TurboGraFX parallel port interface
3755 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
3756 See also Documentation/input/joystick-parport.txt
3758 udbg-immortal [PPC] When debugging early kernel crashes that
3759 happen after console_init() and before a proper
3760 console driver takes over, this boot options might
3761 help "seeing" what's going on.
3763 uhash_entries= [KNL,NET]
3764 Set number of hash buckets for UDP/UDP-Lite connections
3767 [USB] Ignore overcurrent events (default N).
3768 Some badly-designed motherboards generate lots of
3769 bogus events, for ports that aren't wired to
3770 anything. Set this parameter to avoid log spamming.
3771 Note that genuine overcurrent events won't be
3775 [X86] Cause panic on unknown NMI.
3777 usbcore.authorized_default=
3778 [USB] Default USB device authorization:
3779 (default -1 = authorized except for wireless USB,
3780 0 = not authorized, 1 = authorized)
3782 usbcore.autosuspend=
3783 [USB] The autosuspend time delay (in seconds) used
3784 for newly-detected USB devices (default 2). This
3785 is the time required before an idle device will be
3786 autosuspended. Devices for which the delay is set
3787 to a negative value won't be autosuspended at all.
3789 usbcore.usbfs_snoop=
3790 [USB] Set to log all usbfs traffic (default 0 = off).
3792 usbcore.blinkenlights=
3793 [USB] Set to cycle leds on hubs (default 0 = off).
3795 usbcore.old_scheme_first=
3796 [USB] Start with the old device initialization
3797 scheme (default 0 = off).
3799 usbcore.usbfs_memory_mb=
3800 [USB] Memory limit (in MB) for buffers allocated by
3801 usbfs (default = 16, 0 = max = 2047).
3803 usbcore.use_both_schemes=
3804 [USB] Try the other device initialization scheme
3805 if the first one fails (default 1 = enabled).
3807 usbcore.initial_descriptor_timeout=
3808 [USB] Specifies timeout for the initial 64-byte
3809 USB_REQ_GET_DESCRIPTOR request in milliseconds
3810 (default 5000 = 5.0 seconds).
3813 [USBHID] The interval which mice are to be polled at.
3815 usb-storage.delay_use=
3816 [UMS] The delay in seconds before a new device is
3817 scanned for Logical Units (default 1).
3820 [UMS] A list of quirks entries to supplement or
3821 override the built-in unusual_devs list. List
3822 entries are separated by commas. Each entry has
3823 the form VID:PID:Flags where VID and PID are Vendor
3824 and Product ID values (4-digit hex numbers) and
3825 Flags is a set of characters, each corresponding
3826 to a common usb-storage quirk flag as follows:
3827 a = SANE_SENSE (collect more than 18 bytes
3829 b = BAD_SENSE (don't collect more than 18
3830 bytes of sense data);
3831 c = FIX_CAPACITY (decrease the reported
3832 device capacity by one sector);
3833 d = NO_READ_DISC_INFO (don't use
3834 READ_DISC_INFO command);
3835 e = NO_READ_CAPACITY_16 (don't use
3836 READ_CAPACITY_16 command);
3837 f = NO_REPORT_OPCODES (don't use report opcodes
3839 g = MAX_SECTORS_240 (don't transfer more than
3840 240 sectors at a time, uas only);
3841 h = CAPACITY_HEURISTICS (decrease the
3842 reported device capacity by one
3843 sector if the number is odd);
3844 i = IGNORE_DEVICE (don't bind to this
3846 l = NOT_LOCKABLE (don't try to lock and
3847 unlock ejectable media);
3848 m = MAX_SECTORS_64 (don't transfer more
3849 than 64 sectors = 32 KB at a time);
3850 n = INITIAL_READ10 (force a retry of the
3851 initial READ(10) command);
3852 o = CAPACITY_OK (accept the capacity
3853 reported by the device);
3854 p = WRITE_CACHE (the device cache is ON
3856 r = IGNORE_RESIDUE (the device reports
3857 bogus residue values);
3858 s = SINGLE_LUN (the device has only one
3860 t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
3861 commands, uas only);
3862 u = IGNORE_UAS (don't bind to the uas driver);
3863 w = NO_WP_DETECT (don't test whether the
3864 medium is write-protected).
3865 Example: quirks=0419:aaf5:rl,0421:0433:rc
3867 user_debug= [KNL,ARM]
3869 See arch/arm/Kconfig.debug help text.
3870 1 - undefined instruction events
3872 4 - invalid data aborts
3875 Example: user_debug=31
3878 [X86] Flags controlling user PTE allocations.
3880 nohigh = do not allocate PTE pages in
3881 HIGHMEM regardless of setting
3885 On X86_32, this is an alias for vdso32=. Otherwise:
3887 vdso=1: enable VDSO (the default)
3888 vdso=0: disable VDSO mapping
3890 vdso32= [X86] Control the 32-bit vDSO
3891 vdso32=1: enable 32-bit VDSO
3892 vdso32=0 or vdso32=2: disable 32-bit VDSO
3894 See the help text for CONFIG_COMPAT_VDSO for more
3895 details. If CONFIG_COMPAT_VDSO is set, the default is
3896 vdso32=0; otherwise, the default is vdso32=1.
3898 For compatibility with older kernels, vdso32=2 is an
3901 Try vdso32=0 if you encounter an error that says:
3902 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
3905 vector=percpu: enable percpu vector domain
3907 video= [FB] Frame buffer configuration
3908 See Documentation/fb/modedb.txt.
3910 video.brightness_switch_enabled= [0,1]
3911 If set to 1, on receiving an ACPI notify event
3912 generated by hotkey, video driver will adjust brightness
3913 level and then send out the event to user space through
3914 the allocated input device; If set to 0, video driver
3915 will only send out the event without touching backlight
3920 [VMMIO] Memory mapped virtio (platform) device.
3922 <size>@<baseaddr>:<irq>[:<id>]
3924 <size> := size (can use standard suffixes
3926 <baseaddr> := physical base address
3927 <irq> := interrupt number (as passed to
3929 <id> := (optional) platform device id
3931 virtio_mmio.device=1K@0x100b0000:48:7
3933 Can be used multiple times for multiple devices.
3935 vga= [BOOT,X86-32] Select a particular video mode
3936 See Documentation/x86/boot.txt and
3937 Documentation/svga.txt.
3938 Use vga=ask for menu.
3939 This is actually a boot loader parameter; the value is
3940 passed to the kernel using a special protocol.
3942 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
3943 size of <nn>. This can be used to increase the
3944 minimum size (128MB on x86). It can also be used to
3945 decrease the size and leave more room for directly
3948 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
3951 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
3954 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
3958 Controls the behavior of vsyscalls (i.e. calls to
3959 fixed addresses of 0xffffffffff600x00 from legacy
3960 code). Most statically-linked binaries and older
3961 versions of glibc use these calls. Because these
3962 functions are at fixed addresses, they make nice
3963 targets for exploits that can control RIP.
3965 emulate [default] Vsyscalls turn into traps and are
3966 emulated reasonably safely.
3968 native Vsyscalls are native syscall instructions.
3969 This is a little bit faster than trapping
3970 and makes a few dynamic recompilers work
3971 better than they would in emulation mode.
3972 It also makes exploits much easier to write.
3974 none Vsyscalls don't work at all. This makes
3975 them quite hard to use for exploits but
3976 might break your system.
3978 vt.color= [VT] Default text color.
3979 Format: 0xYX, X = foreground, Y = background.
3980 Default: 0x07 = light gray on black.
3982 vt.cur_default= [VT] Default cursor shape.
3983 Format: 0xCCBBAA, where AA, BB, and CC are the same as
3984 the parameters of the <Esc>[?A;B;Cc escape sequence;
3985 see VGA-softcursor.txt. Default: 2 = underline.
3987 vt.default_blu= [VT]
3988 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
3989 Change the default blue palette of the console.
3990 This is a 16-member array composed of values
3993 vt.default_grn= [VT]
3994 Format: <green0>,<green1>,<green2>,...,<green15>
3995 Change the default green palette of the console.
3996 This is a 16-member array composed of values
3999 vt.default_red= [VT]
4000 Format: <red0>,<red1>,<red2>,...,<red15>
4001 Change the default red palette of the console.
4002 This is a 16-member array composed of values
4008 Set system-wide default UTF-8 mode for all tty's.
4009 Default is 1, i.e. UTF-8 mode is enabled for all
4010 newly opened terminals.
4012 vt.global_cursor_default=
4015 Set system-wide default for whether a cursor
4016 is shown on new VTs. Default is -1,
4017 i.e. cursors will be created by default unless
4018 overridden by individual drivers. 0 will hide
4019 cursors, 1 will display them.
4021 vt.italic= [VT] Default color for italic text; 0-15.
4024 vt.underline= [VT] Default color for underlined text; 0-15.
4027 watchdog timers [HW,WDT] For information on watchdog timers,
4028 see Documentation/watchdog/watchdog-parameters.txt
4029 or other driver-specific files in the
4030 Documentation/watchdog/ directory.
4032 workqueue.disable_numa
4033 By default, all work items queued to unbound
4034 workqueues are affine to the NUMA nodes they're
4035 issued on, which results in better behavior in
4036 general. If NUMA affinity needs to be disabled for
4037 whatever reason, this option can be used. Note
4038 that this also can be controlled per-workqueue for
4039 workqueues visible under /sys/bus/workqueue/.
4041 workqueue.power_efficient
4042 Per-cpu workqueues are generally preferred because
4043 they show better performance thanks to cache
4044 locality; unfortunately, per-cpu workqueues tend to
4045 be more power hungry than unbound workqueues.
4047 Enabling this makes the per-cpu workqueues which
4048 were observed to contribute significantly to power
4049 consumption unbound, leading to measurably lower
4050 power usage at the cost of small performance
4053 The default value of this parameter is determined by
4054 the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
4056 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
4057 default x2apic cluster mode on platforms
4060 x86_intel_mid_timer= [X86-32,APBT]
4061 Choose timer option for x86 Intel MID platform.
4062 Two valid options are apbt timer only and lapic timer
4063 plus one apbt timer for broadcast timer.
4064 x86_intel_mid_timer=apbt_only | lapic_and_apbt
4066 xen_emul_unplug= [HW,X86,XEN]
4067 Unplug Xen emulated devices
4068 Format: [unplug0,][unplug1]
4069 ide-disks -- unplug primary master IDE devices
4070 aux-ide-disks -- unplug non-primary-master IDE devices
4071 nics -- unplug network devices
4072 all -- unplug all emulated devices (NICs and IDE disks)
4073 unnecessary -- unplugging emulated devices is
4074 unnecessary even if the host did not respond to
4076 never -- do not unplug even if version check succeeds
4078 xen_nopvspin [X86,XEN]
4079 Disables the ticketlock slowpath using Xen PV
4083 Disables the PV optimizations forcing the HVM guest to
4084 run as generic HVM guest with no PV drivers.
4086 xirc2ps_cs= [NET,PCMCIA]
4088 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
4090 ______________________________________________________________________
4094 Add more DRM drivers.
projects / firefly-linux-kernel-4.4.55.git / blob