4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 ARM ARM architecture is enabled.
44 AVR32 AVR32 architecture is enabled.
45 AX25 Appropriate AX.25 support is enabled.
46 BLACKFIN Blackfin architecture is enabled.
47 DRM Direct Rendering Management support is enabled.
48 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
49 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
50 EFI EFI Partitioning (GPT) is enabled
51 EIDE EIDE/ATAPI support is enabled.
52 EVM Extended Verification Module
53 FB The frame buffer device is enabled.
54 FTRACE Function tracing enabled.
55 GCOV GCOV profiling is enabled.
56 HW Appropriate hardware is enabled.
57 IA-64 IA-64 architecture is enabled.
58 IMA Integrity measurement architecture is enabled.
59 IOSCHED More than one I/O scheduler is enabled.
60 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
61 IPV6 IPv6 support is enabled.
62 ISAPNP ISA PnP code is enabled.
63 ISDN Appropriate ISDN support is enabled.
64 JOY Appropriate joystick support is enabled.
65 KGDB Kernel debugger support is enabled.
66 KVM Kernel Virtual Machine support is enabled.
67 LIBATA Libata driver is enabled
68 LP Printer support is enabled.
69 LOOP Loopback device support is enabled.
70 M68k M68k architecture is enabled.
71 These options have more detailed description inside of
72 Documentation/m68k/kernel-options.txt.
73 MCA MCA bus support is enabled.
74 MDA MDA console support is enabled.
75 MIPS MIPS architecture is enabled.
76 MOUSE Appropriate mouse support is enabled.
77 MSI Message Signaled Interrupts (PCI).
78 MTD MTD (Memory Technology Device) support is enabled.
79 NET Appropriate network support is enabled.
80 NUMA NUMA support is enabled.
81 NFS Appropriate NFS support is enabled.
82 OSS OSS sound support is enabled.
83 PV_OPS A paravirtualized kernel is enabled.
84 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
85 PARISC The PA-RISC architecture is enabled.
86 PCI PCI bus support is enabled.
87 PCIE PCI Express support is enabled.
88 PCMCIA The PCMCIA subsystem is enabled.
89 PNP Plug & Play support is enabled.
90 PPC PowerPC architecture is enabled.
91 PPT Parallel port support is enabled.
92 PS2 Appropriate PS/2 support is enabled.
93 RAM RAM disk support is enabled.
94 S390 S390 architecture is enabled.
95 SCSI Appropriate SCSI support is enabled.
96 A lot of drivers have their options described inside
97 the Documentation/scsi/ sub-directory.
98 SECURITY Different security models are enabled.
99 SELINUX SELinux support is enabled.
100 APPARMOR AppArmor support is enabled.
101 SERIAL Serial support is enabled.
102 SH SuperH architecture is enabled.
103 SMP The kernel is an SMP kernel.
104 SPARC Sparc architecture is enabled.
105 SWSUSP Software suspend (hibernation) is enabled.
106 SUSPEND System suspend states are enabled.
107 TPM TPM drivers are enabled.
108 TS Appropriate touchscreen support is enabled.
109 UMS USB Mass Storage support is enabled.
110 USB USB support is enabled.
111 USBHID USB Human Interface Device support is enabled.
112 V4L Video For Linux support is enabled.
113 VGA The VGA console has been enabled.
114 VT Virtual terminal support is enabled.
115 WDT Watchdog support is enabled.
116 XT IBM PC/XT MFM hard disk support is enabled.
117 X86-32 X86-32, aka i386 architecture is enabled.
118 X86-64 X86-64 architecture is enabled.
119 More X86-64 boot options can be found in
120 Documentation/x86/x86_64/boot-options.txt .
121 X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
122 XEN Xen support is enabled
124 In addition, the following text indicates that the option:
126 BUGS= Relates to possible processor bugs on the said processor.
127 KNL Is a kernel start-up parameter.
128 BOOT Is a boot loader parameter.
130 Parameters denoted with BOOT are actually interpreted by the boot
131 loader, and have no meaning to the kernel directly.
132 Do not modify the syntax of boot loader parameters without extreme
133 need or coordination with <Documentation/x86/boot.txt>.
135 There are also arch-specific kernel-parameters not documented here.
136 See for example <Documentation/x86/x86_64/boot-options.txt>.
138 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
139 a trailing = on the name of any parameter states that that parameter will
140 be entered as an environment variable, whereas its absence indicates that
141 it will appear as a kernel argument readable via /proc/cmdline by programs
142 running once the system is up.
144 The number of kernel parameters is not limited, but the length of the
145 complete command line (parameters including spaces etc.) is limited to
146 a fixed number of characters. This limit depends on the architecture
147 and is between 256 and 4096 characters. It is defined in the file
148 ./include/asm/setup.h as COMMAND_LINE_SIZE.
150 Finally, the [KMG] suffix is commonly described after a number of kernel
151 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
152 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
153 bytes respectively. Such letter suffixes can also be entirely omitted.
157 Advanced Configuration and Power Interface
158 Format: { force | off | strict | noirq | rsdt }
159 force -- enable ACPI if default was off
160 off -- disable ACPI if default was on
161 noirq -- do not use ACPI for IRQ routing
162 strict -- Be less tolerant of platforms that are not
163 strictly ACPI specification compliant.
164 rsdt -- prefer RSDT over (default) XSDT
165 copy_dsdt -- copy DSDT to memory
167 See also Documentation/power/runtime_pm.txt, pci=noacpi
169 acpi_rsdp= [ACPI,EFI,KEXEC]
170 Pass the RSDP address to the kernel, mostly used
171 on machines running EFI runtime service to boot the
172 second kernel for kdump.
174 acpi_apic_instance= [ACPI, IOAPIC]
176 2: use 2nd APIC table, if available
177 1,0: use 1st APIC table
180 acpi_backlight= [HW,ACPI]
181 acpi_backlight=vendor
183 If set to vendor, prefer vendor specific driver
184 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
185 of the ACPI video.ko driver.
187 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
188 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
190 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
191 debug output. Bits in debug_layer correspond to a
192 _COMPONENT in an ACPI source file, e.g.,
193 #define _COMPONENT ACPI_PCI_COMPONENT
194 Bits in debug_level correspond to a level in
195 ACPI_DEBUG_PRINT statements, e.g.,
196 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
197 The debug_level mask defaults to "info". See
198 Documentation/acpi/debug.txt for more information about
199 debug layers and levels.
201 Enable processor driver info messages:
202 acpi.debug_layer=0x20000000
203 Enable PCI/PCI interrupt routing info messages:
204 acpi.debug_layer=0x400000
205 Enable AML "Debug" output, i.e., stores to the Debug
206 object while interpreting AML:
207 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
208 Enable all messages related to ACPI hardware:
209 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
211 Some values produce so much output that the system is
212 unusable. The "log_buf_len" parameter may be useful
213 if you need to capture more output.
215 acpi_irq_balance [HW,ACPI]
216 ACPI will balance active IRQs
219 acpi_irq_nobalance [HW,ACPI]
220 ACPI will not move active IRQs (default)
223 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
224 Format: <irq>,<irq>...
226 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
228 Format: <irq>,<irq>...
230 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
232 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
233 Format: To spoof as Windows 98: ="Microsoft Windows"
235 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
236 acpi_osi="string1" # add string1 -- only one string
237 acpi_osi="!string2" # remove built-in string2
238 acpi_osi= # disable all strings
241 Override the pmtimer bug detection: force the kernel
242 to assume that this machine's pmtimer latches its value
243 and always returns good values.
245 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
246 Format: { level | edge | high | low }
248 acpi_serialize [HW,ACPI] force serialization of AML methods
250 acpi_skip_timer_override [HW,ACPI]
251 Recognize and ignore IRQ0/pin2 Interrupt Override.
252 For broken nForce2 BIOS resulting in XT-PIC timer.
254 acpi_sleep= [HW,ACPI] Sleep options
255 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
256 old_ordering, nonvs, sci_force_enable }
257 See Documentation/power/video.txt for information on
259 s3_beep is for debugging; it makes the PC's speaker beep
260 as soon as the kernel's real-mode entry point is called.
261 s4_nohwsig prevents ACPI hardware signature from being
262 used during resume from hibernation.
263 old_ordering causes the ACPI 1.0 ordering of the _PTS
264 control method, with respect to putting devices into
265 low power states, to be enforced (the ACPI 2.0 ordering
266 of _PTS is used by default).
267 nonvs prevents the kernel from saving/restoring the
268 ACPI NVS memory during suspend/hibernation and resume.
269 sci_force_enable causes the kernel to set SCI_EN directly
270 on resume from S1/S3 (which is against the ACPI spec,
271 but some broken systems don't work without it).
273 acpi_use_timer_override [HW,ACPI]
274 Use timer override. For some broken Nvidia NF5 boards
275 that require a timer override, but don't have HPET
277 acpi_enforce_resources= [ACPI]
278 { strict | lax | no }
279 Check for resource conflicts between native drivers
280 and ACPI OperationRegions (SystemIO and SystemMemory
281 only). IO ports and memory declared in ACPI might be
282 used by the ACPI subsystem in arbitrary AML code and
283 can interfere with legacy drivers.
284 strict (default): access to resources claimed by ACPI
285 is denied; legacy drivers trying to access reserved
286 resources will fail to bind to device using them.
287 lax: access to resources claimed by ACPI is allowed;
288 legacy drivers trying to access reserved resources
289 will bind successfully but a warning message is logged.
290 no: ACPI OperationRegions are not marked as reserved,
291 no further checks are performed.
293 add_efi_memmap [EFI; X86] Include EFI memory map in
294 kernel's map of available physical RAM.
297 { off | try_unsupported }
298 off: disable AGP support
299 try_unsupported: try to drive unsupported chipsets
300 (may crash computer or cause data corruption)
303 See Documentation/sound/alsa/alsa-parameters.txt
306 Allow the default userspace alignment fault handler
307 behaviour to be specified. Bit 0 enables warnings,
308 bit 1 enables fixups, and bit 2 sends a segfault.
310 align_va_addr= [X86-64]
311 Align virtual addresses by clearing slice [14:12] when
312 allocating a VMA at process creation time. This option
313 gives you up to 3% performance improvement on AMD F15h
314 machines (where it is enabled by default) for a
315 CPU-intensive style benchmark, and it can vary highly in
316 a microbenchmark depending on workload and compiler.
318 32: only for 32-bit processes
319 64: only for 64-bit processes
320 on: enable for both 32- and 64-bit processes
321 off: disable for both 32- and 64-bit processes
323 amd_iommu= [HW,X86-64]
324 Pass parameters to the AMD IOMMU driver in the system.
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
330 off - do not initialize any AMD IOMMU found in
333 amijoy.map= [HW,JOY] Amiga joystick support
334 Map of devices attached to JOY0DAT and JOY1DAT
336 See also Documentation/input/joystick.txt
338 analog.map= [HW,JOY] Analog joystick and gamepad support
339 Specifies type or capabilities of an analog joystick
340 connected to one of 16 gameports
341 Format: <type1>,<type2>,..<type16>
344 Power management functions (SPARCstation-4/5 + deriv.)
346 Disable APC CPU standby support. SPARCstation-Fox does
347 not play well with APC CPU idle - disable it if you have
348 APC and your system crashes randomly.
350 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
351 Change the output verbosity whilst booting
352 Format: { quiet (default) | verbose | debug }
353 Change the amount of debugging information output
354 when initialising the APIC and IO-APIC components.
357 See Documentation/networking/ipv6.txt.
359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
368 apm= [APM] Advanced Power Management
369 See header of arch/x86/kernel/apm_32.c.
371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
376 atarimouse= [HW,MOUSE] Atari Mouse
378 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
379 EzKey and similar keyboards
381 atkbd.reset= [HW] Reset keyboard during initialization
383 atkbd.set= [HW] Select keyboard code set
384 Format: <int> (2 = AT (default), 3 = PS/2)
386 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 atkbd.softraw= [HW] Choose between synthetic and real raw mode
390 Format: <bool> (0 = real, 1 = synthetic (default))
392 atkbd.softrepeat= [HW]
393 Use software keyboard repeat
397 baycom_epp= [HW,AX25]
400 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
402 See header of drivers/net/hamradio/baycom_par.c.
404 baycom_ser_fdx= [HW,AX25]
405 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
406 Format: <io>,<irq>,<mode>[,<baud>]
407 See header of drivers/net/hamradio/baycom_ser_fdx.c.
409 baycom_ser_hdx= [HW,AX25]
410 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
411 Format: <io>,<irq>,<mode>
412 See header of drivers/net/hamradio/baycom_ser_hdx.c.
414 boot_delay= Milliseconds to delay each printk during boot.
415 Values larger than 10 seconds (10000) are changed to
419 bootmem_debug [KNL] Enable bootmem allocator debug messages.
421 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
422 bttv.radio= Most important insmod options are available as
424 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bulk_remove=off [PPC] This parameter disables the use of the pSeries
428 firmware feature for flushing multiple hpte entries
431 c101= [NET] Moxa C101 synchronous serial card
433 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
434 Sometimes CPU hardware bugs make them report the cache
435 size incorrectly. The kernel will attempt work arounds
436 to fix known problems, but for some CPUs it is not
437 possible to determine what the correct size should be.
438 This option provides an override for these situations.
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
460 Value can be changed at runtime via
461 /selinux/checkreqprot.
464 See Documentation/s390/CommonIO for details.
466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
468 Forces specified clocksource (if available) to be used
469 when calculating gettimeofday(). If specified
470 clocksource is not available, it defaults to PIT.
471 Format: { pit | tsc | cyclone | pmtmr }
473 clocksource= Override the default clocksource
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
479 [all] jiffies (this is the base, fallback clocksource)
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
484 [X86-32] pit,hpet,tsc;
485 scx200_hrt on Geode; cyclone on IBM x440
493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
495 arch/x86/include/asm/cpufeature.h for the valid bit
496 numbers. Note the Linux specific bits are not necessarily
497 stable over kernel options, but the vendor specific
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
506 cmo_free_hint= [PPC] Format: { yes | no }
507 Specify whether pages are marked as being inactive
508 when they are freed. This is used in CMO environments
509 to determine OS memory pressure for page stealing by
513 code_bytes [X86] How many bytes of object code to print
518 com20020= [HW,NET] ARCnet - COM20020 chipset
520 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
522 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
526 ARCnet - COM90xx chipset (memory-mapped buffers)
527 Format: <io>[,<irq>[,<memstart>]]
529 condev= [HW,S390] console device
532 console= [KNL] Output console device and options.
534 tty<n> Use the virtual console device <n>.
538 Use the specified serial port. The options are of
539 the form "bbbbpnf", where "bbbb" is the baud rate,
540 "p" is parity ("n", "o", or "e"), "n" is number of
541 bits, and "f" is flow control ("r" for RTS or
542 omit it). Default is "9600n8".
544 See Documentation/serial-console.txt for more
546 Documentation/networking/netconsole.txt for an
549 uart[8250],io,<addr>[,options]
550 uart[8250],mmio,<addr>[,options]
551 Start an early, polled-mode console on the 8250/16550
552 UART at the specified I/O port or MMIO address,
553 switching to the matching ttyS device later. The
554 options are the same as for ttyS, above.
556 If the device connected to the port is not a TTY but a braille
557 device, prepend "brl," before the device type, for instance
559 For now, only VisioBraille is supported.
561 consoleblank= [KNL] The console blank (screen saver) timeout in
562 seconds. Defaults to 10*60 = 10mins. A value of 0
563 disables the blank timer.
566 [KNL] Change the default value for
567 /proc/<pid>/coredump_filter.
568 See also Documentation/filesystems/proc.txt.
570 cpuidle.off=1 [CPU_IDLE]
571 disable the cpuidle sub-system
573 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
575 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
577 crashkernel=size[KMG][@offset[KMG]]
578 [KNL] Using kexec, Linux can switch to a 'crash kernel'
579 upon panic. This parameter reserves the physical
580 memory region [offset, offset + size] for that kernel
581 image. If '@offset' is omitted, then a suitable offset
582 is selected automatically. Check
583 Documentation/kdump/kdump.txt for further details.
585 crashkernel=range1:size1[,range2:size2,...][@offset]
586 [KNL] Same as above, but depends on the memory
587 in the running system. The syntax of range is
588 start-[end] where start and end are both
589 a memory unit (amount[KMG]). See also
590 Documentation/kdump/kdump.txt for an example.
595 cs89x0_media= [HW,NET]
596 Format: { rj45 | aui | bnc }
599 See header of drivers/s390/block/dasd_devmap.c.
601 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
602 (one device per port)
603 Format: <port#>,<type>
604 See also Documentation/input/joystick-parport.txt
606 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
607 time. See Documentation/dynamic-debug-howto.txt for
610 debug [KNL] Enable kernel debugging (events log level).
613 [KNL] verbose self-tests
615 Print debugging info while doing the locking API
617 We default to 0 (no extra messages), setting it to
618 1 will print _a lot_ more information - normally
619 only useful to kernel developers.
621 debug_objects [KNL] Enable object debugging
624 [KNL] Disable object debugging
626 debug_guardpage_minorder=
627 [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
628 parameter allows control of the order of pages that will
629 be intentionally kept free (and hence protected) by the
630 buddy allocator. Bigger value increase the probability
631 of catching random memory corruption, but reduce the
632 amount of memory for normal system use. The maximum
633 possible value is MAX_ORDER/2. Setting this parameter
634 to 1 or 2 should be enough to identify most random
635 memory corruption problems caused by bugs in kernel or
636 driver code when a CPU writes to (or reads from) a
637 random memory location. Note that there exists a class
638 of memory corruptions problems caused by buggy H/W or
639 F/W or by drivers badly programing DMA (basically when
640 memory is written at bus level and the CPU MMU is
641 bypassed) which are not detectable by
642 CONFIG_DEBUG_PAGEALLOC, hence this option will not help
643 tracking down these problems.
645 debugpat [X86] Enable PAT debugging
647 decnet.addr= [HW,NET]
648 Format: <area>[,<node>]
649 See also Documentation/networking/decnet.txt.
652 [same as hugepagesz=] The size of the default
653 HugeTLB page size. This is the size represented by
654 the legacy /proc/ hugepages APIs, used for SHM, and
655 default size when mounting hugetlbfs filesystems.
656 Defaults to the default architecture's huge page size
660 Set number of hash buckets for dentry cache.
663 IO parameters + enable/disable command.
665 digiepca= [HW,SERIAL]
666 See drivers/char/README.epca and
667 Documentation/serial/digiepca.txt.
670 See Documentation/networking/ipv6.txt.
672 disable_ddw [PPC/PSERIES]
673 Disable Dynamic DMA Window support. Use this if
674 to workaround buggy firmware.
677 See Documentation/networking/ipv6.txt.
679 disable_mtrr_cleanup [X86]
680 The kernel tries to adjust MTRR layout from continuous
681 to discrete, to make X server driver able to add WB
682 entry later. This parameter disables that.
684 disable_mtrr_trim [X86, Intel and AMD only]
685 By default the kernel will trim any uncacheable
686 memory out of your available memory pool based on
687 MTRR settings. This parameter disables that behavior,
688 possibly causing your machine to run very slowly.
690 disable_timer_pin_1 [X86]
691 Disable PIN 1 of APIC timer
692 Can be useful to work around chipset bugs.
694 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
695 this option disables the debugging code at boot.
697 dma_debug_entries=<number>
698 This option allows to tune the number of preallocated
699 entries for DMA-API debugging code. One entry is
700 required per DMA-API allocation. Use this if the
701 DMA-API debugging code disables itself because the
702 architectural default is too low.
704 dma_debug_driver=<driver_name>
705 With this option the DMA-API debugging driver
706 filter feature can be enabled at boot time. Just
707 pass the driver to filter for as the parameter.
708 The filter can be disabled or changed to another
709 driver later using sysfs.
713 earlycon= [KNL] Output early console device and options.
714 uart[8250],io,<addr>[,options]
715 uart[8250],mmio,<addr>[,options]
716 uart[8250],mmio32,<addr>[,options]
717 Start an early, polled-mode console on the 8250/16550
718 UART at the specified I/O port or MMIO address.
719 MMIO inter-register address stride is either 8-bit
720 (mmio) or 32-bit (mmio32).
721 The options are the same as for ttyS, above.
723 earlyprintk= [X86,SH,BLACKFIN]
725 earlyprintk=serial[,ttySn[,baudrate]]
726 earlyprintk=ttySn[,baudrate]
727 earlyprintk=dbgp[debugController#]
729 Append ",keep" to not disable it when the real console
732 Only vga or serial or usb debug port at a time.
734 Currently only ttyS0 and ttyS1 are supported.
736 Interaction with the standard serial driver is not
739 The VGA output is eventually overwritten by the real
742 ekgdboc= [X86,KGDB] Allow early kernel console debugging
745 This is designed to be used in conjunction with
746 the boot argument: earlyprintk=vga
749 Format: {"off" | "on" | "skip[mbr]"}
751 eisa_irq_edge= [PARISC,HW]
752 See header of drivers/parisc/eisa.c.
755 See comment before function elanfreq_setup() in
756 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
759 Format: {"cfq" | "deadline" | "noop"}
760 See Documentation/block/cfq-iosched.txt and
761 Documentation/block/deadline-iosched.txt for details.
763 elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
764 Specifies physical address of start of kernel core
765 image elf header and optionally the size. Generally
766 kexec loader will pass this option to capture kernel.
767 See Documentation/kdump/kdump.txt for details.
769 enable_mtrr_cleanup [X86]
770 The kernel tries to adjust MTRR layout from continuous
771 to discrete, to make X server driver able to add WB
772 entry later. This parameter enables that.
774 enable_timer_pin_1 [X86]
775 Enable PIN 1 of APIC timer
776 Can be useful to work around chipset bugs
777 (in particular on some ATI chipsets).
778 The kernel tries to set a reasonable default.
780 enforcing [SELINUX] Set initial enforcing status.
782 See security/selinux/Kconfig help text.
783 0 -- permissive (log only, no denials).
784 1 -- enforcing (deny and log).
786 Value can be changed at runtime via /selinux/enforce.
789 Disable Error Record Serialization Table (ERST)
792 ether= [HW,NET] Ethernet cards parameters
793 This option is obsoleted by the "netdev=" option, which
794 has equivalent usage. See its documentation for details.
798 Permit 'security.evm' to be updated regardless of
799 current integrity status.
803 fail_make_request=[KNL]
804 General fault injection mechanism.
805 Format: <interval>,<probability>,<space>,<times>
806 See also Documentation/fault-injection/.
809 See Documentation/blockdev/floppy.txt.
811 force_pal_cache_flush
812 [IA-64] Avoid check_sal_cache_flush which may hang on
813 buggy SAL_CACHE_FLUSH implementations. Using this
814 parameter will force ia64_sal_cache_flush to call
815 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
818 [FTRACE] will set and start the specified tracer
819 as early as possible in order to facilitate early
822 ftrace_dump_on_oops[=orig_cpu]
823 [FTRACE] will dump the trace buffers on oops.
824 If no parameter is passed, ftrace will dump
825 buffers of all CPUs, but if you pass orig_cpu, it will
826 dump only the buffer of the CPU that triggered the
829 ftrace_filter=[function-list]
830 [FTRACE] Limit the functions traced by the function
831 tracer at boot up. function-list is a comma separated
832 list of functions. This list can be changed at run
833 time by the set_ftrace_filter file in the debugfs
836 ftrace_notrace=[function-list]
837 [FTRACE] Do not trace the functions specified in
838 function-list. This list can be changed at run time
839 by the set_ftrace_notrace file in the debugfs
842 ftrace_graph_filter=[function-list]
843 [FTRACE] Limit the top level callers functions traced
844 by the function graph tracer at boot up.
845 function-list is a comma separated list of functions
846 that can be changed at run time by the
847 set_graph_function file in the debugfs tracing directory.
850 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
851 support via parallel port (up to 5 devices per port)
852 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
853 See also Documentation/input/joystick-parport.txt
857 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
861 gcov_persist= [GCOV] When non-zero (default), profiling data for
862 kernel modules is saved and remains accessible via
863 debugfs, even when the module is unloaded/reloaded.
864 When zero, profiling data is discarded and associated
865 debugfs files are removed at module unload time.
867 gpt [EFI] Forces disk with valid GPT signature but
868 invalid Protective MBR to be treated as GPT.
870 hashdist= [KNL,NUMA] Large hashes allocated during boot
871 are distributed across NUMA nodes. Defaults on
872 for 64-bit NUMA, off otherwise.
873 Format: 0 | 1 (for off | on)
875 hcl= [IA-64] SGI's Hardware Graph compatibility layer
877 hd= [EIDE] (E)IDE hard drive subsystem geometry
878 Format: <cyl>,<head>,<sect>
881 Disable Hardware Error Source Table (HEST) support;
882 corresponding firmware-first mode error processing
883 logic will be disabled.
885 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
886 size of <nn>. This works even on boxes that have no
887 highmem otherwise. This also works to reduce highmem
888 size on bigger boxes.
890 highres= [KNL] Enable/disable high resolution timer mode.
891 Valid parameters: "on", "off"
895 See Documentation/isdn/README.HiSax.
899 hpet= [X86-32,HPET] option to control HPET usage
900 Format: { enable (default) | disable | force |
902 disable: disable HPET and use PIT instead
903 force: allow force enabled of undocumented chips (ICH4,
905 verbose: show contents of HPET registers during setup
907 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
908 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
909 On x86-64 and powerpc, this option can be specified
910 multiple times interleaved with hugepages= to reserve
911 huge pages of different sizes. Valid pages sizes on
912 x86-64 are 2M (when the CPU supports "pse") and 1G
913 (when the CPU supports the "pdpe1gb" cpuinfo flag)
914 Note that 1GB pages can only be allocated at boot time
915 using hugepages= and not freed afterwards.
917 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
918 terminal devices. Valid values: 0..8
919 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
920 If specified, z/VM IUCV HVC accepts connections
921 from listed z/VM user IDs only.
924 Do not unregister boot console at start. This is only
925 useful for debugging when something happens in the window
926 between unregistering the boot console and initializing
929 i2c_bus= [HW] Override the default board specific I2C bus speed
930 or register an additional I2C bus that is not
931 registered from board initialization code.
935 i8042.debug [HW] Toggle i8042 debug mode
936 i8042.direct [HW] Put keyboard port into non-translated mode
937 i8042.dumbkbd [HW] Pretend that controller can only read data from
938 keyboard and cannot control its state
939 (Don't attempt to blink the leds)
940 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
941 i8042.nokbd [HW] Don't check/create keyboard port
942 i8042.noloop [HW] Disable the AUX Loopback command while probing
944 i8042.nomux [HW] Don't check presence of an active multiplexing
946 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
948 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
949 i8042.reset [HW] Reset the controller during init and cleanup
950 i8042.unlock [HW] Unlock (ignore) the keylock
954 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
955 indicates that the driver is running on unsupported
957 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
958 does not match list of supported models.
960 [HW] Report power status in /proc/i8k
961 (disabled by default)
962 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
966 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
968 ide-core.nodma= [HW] (E)IDE subsystem
969 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
970 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
971 .cdrom .chs .ignore_cable are additional options
972 See Documentation/ide/ide.txt.
974 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
975 Claim all unknown PCI IDE storage controllers.
978 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
979 Poll forces a polling idle loop that can slightly
980 improve the performance of waking up a idle CPU, but
981 will use a lot of power and make the system run hot.
983 idle=mwait: On systems which support MONITOR/MWAIT but
984 the kernel chose to not use it because it doesn't save
985 as much power as a normal idle loop, use the
986 MONITOR/MWAIT idle loop anyways. Performance should be
987 the same as idle=poll.
988 idle=halt: Halt is forced to be used for CPU idle.
989 In such case C2/C3 won't be used again.
990 idle=nomwait: Disable mwait for CPU C-states
992 ignore_loglevel [KNL]
993 Ignore loglevel setting - this will print /all/
994 kernel messages to the console. Useful for debugging.
995 We also add it as printk module parameter, so users
996 could change it dynamically, usually by
997 /sys/module/printk/parameters/ignore_loglevel.
1000 Set number of hash buckets for inode cache.
1003 Format: { "0" | "1" }
1004 0 -- integrity auditing messages. (Default)
1005 1 -- enable informational integrity auditing messages.
1008 Format: { "sha1" | "md5" }
1012 Load a policy which meets the needs of the Trusted
1013 Computing Base. This means IMA will measure all
1014 programs exec'd, files mmap'd for exec, and all files
1015 opened for read by uid=0.
1019 Run specified binary instead of /sbin/init as init
1022 initcall_debug [KNL] Trace initcalls as they are executed. Useful
1023 for working out where the kernel is dying during
1026 initrd= [BOOT] Specify the location of the initial ramdisk
1028 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1031 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1033 Enable intel iommu driver.
1035 Disable intel iommu driver.
1036 igfx_off [Default Off]
1037 By default, gfx is mapped as normal device. If a gfx
1038 device has a dedicated DMAR unit, the DMAR unit is
1039 bypassed by not enabling DMAR with this option. In
1040 this case, gfx device will use physical address for
1043 With this option iommu will not optimize to look
1044 for io virtual address below 32-bit forcing dual
1045 address cycle on pci bus for cards supporting greater
1046 than 32-bit addressing. The default is to look
1047 for translation below 32-bit and if not available
1048 then look in the higher range.
1049 strict [Default Off]
1050 With this option on every unmap_single operation will
1051 result in a hardware IOTLB flush operation as opposed
1052 to batching them for performance.
1053 sp_off [Default Off]
1054 By default, super page will be supported if Intel IOMMU
1055 has the capability. With this option, super page will
1057 intremap= [X86-64, Intel-IOMMU]
1058 on enable Interrupt Remapping (default)
1059 off disable Interrupt Remapping
1060 nosid disable Source ID checking
1062 BIOS x2APIC opt-out request will be ignored
1066 iomem= Disable strict checking of access to MMIO memory
1067 strict regions from userspace.
1082 group_mf [x86, IA-64]
1085 io7= [HW] IO7 for Marvel based alpha systems
1086 See comment before marvel_specify_io7 in
1087 arch/alpha/kernel/core_marvel.c.
1089 io_delay= [X86] I/O delay method
1091 Standard port 0x80 based delay
1093 Alternate port 0xed based delay (needed on some systems)
1095 Simple two microseconds delay
1100 See Documentation/filesystems/nfs/nfsroot.txt.
1102 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1103 See comment before ip2_setup() in
1104 drivers/char/ip2/ip2base.c.
1107 When an interrupt is not handled search all handlers
1108 for it. Intended to get systems with badly broken
1112 When an interrupt is not handled search all handlers
1113 for it. Also check all handlers each timer
1114 interrupt. Intended to get systems with badly broken
1118 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1120 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1122 <cpu number>,...,<cpu number>
1124 <cpu number>-<cpu number>
1125 (must be a positive range in ascending order)
1127 <cpu number>,...,<cpu number>-<cpu number>
1129 This option can be used to specify one or more CPUs
1130 to isolate from the general SMP balancing and scheduling
1131 algorithms. You can move a process onto or off an
1132 "isolated" CPU via the CPU affinity syscalls or cpuset.
1133 <cpu number> begins at 0 and the maximum value is
1134 "number of CPUs in system - 1".
1136 This option is the preferred way to isolate CPUs. The
1137 alternative -- manually setting the CPU mask of all
1138 tasks in the system -- can cause problems and
1139 suboptimal load balancer performance.
1143 js= [HW,JOY] Analog joystick
1144 See Documentation/input/joystick.txt.
1148 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1149 specifies the amount of memory usable by the kernel
1150 for non-movable allocations. The requested amount is
1151 spread evenly throughout all nodes in the system. The
1152 remaining memory in each node is used for Movable
1153 pages. In the event, a node is too small to have both
1154 kernelcore and Movable pages, kernelcore pages will
1155 take priority and other nodes will have a larger number
1156 of kernelcore pages. The Movable zone is used for the
1157 allocation of pages that may be reclaimed or moved
1158 by the page migration subsystem. This means that
1159 HugeTLB pages may not be allocated from this zone.
1160 Note that allocations like PTEs-from-HighMem still
1161 use the HighMem zone if it exists, and the Normal
1162 zone if it does not.
1164 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1165 Format: <Controller#>[,poll interval]
1166 The controller # is the number of the ehci usb debug
1167 port as it is probed via PCI. The poll interval is
1168 optional and is the number seconds in between
1169 each poll cycle to the debug port in case you need
1170 the functionality for interrupting the kernel with
1171 gdb or control-c on the dbgp connection. When
1172 not using this parameter you use sysrq-g to break into
1173 the kernel debugger.
1175 kgdboc= [KGDB,HW] kgdb over consoles.
1176 Requires a tty driver that supports console polling,
1177 or a supported polling keyboard driver (non-usb).
1178 Serial only format: <serial_device>[,baud]
1179 keyboard only format: kbd
1180 keyboard and serial format: kbd,<serial_device>[,baud]
1181 Optional Kernel mode setting:
1182 kms, kbd format: kms,kbd
1183 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1185 kgdbwait [KGDB] Stop kernel execution and enter the
1186 kernel debugger at the earliest opportunity.
1188 kmac= [MIPS] korina ethernet MAC address.
1189 Configure the RouterBoard 532 series on-chip
1190 Ethernet adapter MAC address.
1192 kmemleak= [KNL] Boot-time kmemleak enable/disable
1193 Valid arguments: on, off
1196 kstack=N [X86] Print N words from the kernel stack
1199 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1200 Default is 0 (don't ignore, but inject #GP)
1202 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1203 Default is 1 (enabled)
1205 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1209 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1210 Default is 1 (enabled)
1212 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1214 Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
1216 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1217 (virtualized MMU) support on capable Intel chips.
1218 Default is 1 (enabled)
1220 kvm-intel.emulate_invalid_guest_state=
1221 [KVM,Intel] Enable emulation of invalid guest states
1222 Default is 0 (disabled)
1224 kvm-intel.flexpriority=
1225 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1226 Default is 1 (enabled)
1229 [KVM,Intel] Enable VMX nesting (nVMX).
1230 Default is 0 (disabled)
1232 kvm-intel.unrestricted_guest=
1233 [KVM,Intel] Disable unrestricted guest feature
1234 (virtualized real and unpaged mode) on capable
1235 Intel chips. Default is 1 (enabled)
1237 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1238 feature (tagged TLBs) on capable Intel chips.
1239 Default is 1 (enabled)
1245 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1248 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1251 libata.dma= [LIBATA] DMA control
1252 libata.dma=0 Disable all PATA and SATA DMA
1253 libata.dma=1 PATA and SATA Disk DMA only
1254 libata.dma=2 ATAPI (CDROM) DMA only
1255 libata.dma=4 Compact Flash DMA only
1256 Combinations also work, so libata.dma=3 enables DMA
1257 for disks and CDROMs, but not CFs.
1259 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1260 libata.ignore_hpa=0 keep BIOS limits (default)
1261 libata.ignore_hpa=1 ignore limits, using full disk
1263 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1267 libata.force= [LIBATA] Force configurations. The format is comma
1268 separated list of "[ID:]VAL" where ID is
1269 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1270 matching port, link or device. Basically, it matches
1271 the ATA ID string printed on console by libata. If
1272 the whole ID part is omitted, the last PORT and DEVICE
1273 values are used. If ID hasn't been specified yet, the
1274 configuration applies to all ports, links and devices.
1276 If only DEVICE is omitted, the parameter applies to
1277 the port and all links and devices behind it. DEVICE
1278 number of 0 either selects the first device or the
1279 first fan-out link behind PMP device. It does not
1280 select the host link. DEVICE number of 15 selects the
1281 host link and device attached to it.
1283 The VAL specifies the configuration to force. As long
1284 as there's no ambiguity shortcut notation is allowed.
1285 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1286 The following configurations can be forced.
1288 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1289 Any ID with matching PORT is used.
1291 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1293 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1294 udma[/][16,25,33,44,66,100,133] notation is also
1297 * [no]ncq: Turn on or off NCQ.
1299 * nohrst, nosrst, norst: suppress hard, soft
1302 * dump_id: dump IDENTIFY data.
1304 If there are multiple matching configurations changing
1305 the same attribute, the last one is used.
1307 memblock=debug [KNL] Enable memblock debug messages.
1309 load_ramdisk= [RAM] List of ramdisks to load from floppy
1310 See Documentation/blockdev/ramdisk.txt.
1312 lockd.nlm_grace_period=P [NFS] Assign grace period.
1315 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1318 lockd.nlm_timeout=T [NFS] Assign timeout value.
1321 lockd.nlm_udpport=M [NFS] Assign UDP port.
1324 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1327 loglevel= All Kernel Messages with a loglevel smaller than the
1328 console loglevel will be printed to the console. It can
1329 also be changed with klogd or other programs. The
1330 loglevels are defined as follows:
1332 0 (KERN_EMERG) system is unusable
1333 1 (KERN_ALERT) action must be taken immediately
1334 2 (KERN_CRIT) critical conditions
1335 3 (KERN_ERR) error conditions
1336 4 (KERN_WARNING) warning conditions
1337 5 (KERN_NOTICE) normal but significant condition
1338 6 (KERN_INFO) informational
1339 7 (KERN_DEBUG) debug-level messages
1341 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1342 in bytes. n must be a power of two. The default
1343 size is set in the kernel config file.
1345 logo.nologo [FB] Disables display of the built-in Linux logo.
1346 This may be used to provide more screen space for
1347 kernel log messages and is useful when debugging
1348 kernel boot problems.
1350 lp=0 [LP] Specify parallel ports to use, e.g,
1351 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1352 lp=reset first parallel port). 'lp=0' disables the
1353 lp=auto printer driver. 'lp=reset' (which can be
1354 specified in addition to the ports) causes
1355 attached printers to be reset. Using
1356 lp=port1,port2,... specifies the parallel ports
1357 to associate lp devices with, starting with
1358 lp0. A port specification may be 'none' to skip
1359 that lp device, or a parport name such as
1360 'parport0'. Specifying 'lp=auto' instead of a
1361 port specification list means that device IDs
1362 from each port should be examined, to see if
1363 an IEEE 1284-compliant printer is attached; if
1364 so, the driver will manage that printer.
1365 See also header of drivers/char/lp.c.
1368 Sets loops_per_jiffy to given constant, thus avoiding
1369 time-consuming boot-time autodetection (up to 250 ms per
1370 CPU). 0 enables autodetection (default). To determine
1371 the correct value for your kernel, boot with normal
1372 autodetection and see what value is printed. Note that
1373 on SMP systems the preset will be applied to all CPUs,
1374 which is likely to cause problems if your CPUs need
1375 significantly divergent settings. An incorrect value
1376 will cause delays in the kernel to be wrong, leading to
1377 unpredictable I/O errors and other breakage. Although
1378 unlikely, in the extreme case this might damage your
1382 Format: <io>,<irq>,<dma>
1384 machvec= [IA-64] Force the use of a particular machine-vector
1385 (machvec) in a generic kernel.
1386 Example: machvec=hpzx1_swiotlb
1388 machtype= [Loongson] Share the same kernel image file between different
1390 Example: machtype=lemote-yeeloong-2f-7inch
1392 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1393 than or equal to this physical address is ignored.
1395 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1396 should make use of. maxcpus=n : n >= 0 limits the
1397 kernel to using 'n' processors. n=0 is a special case,
1398 it is equivalent to "nosmp", which also disables
1401 max_loop= [LOOP] The number of loop block devices that get
1402 (loop.max_loop) unconditionally pre-created at init time. The default
1403 number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
1404 of statically allocating a predefined number, loop
1405 devices can be requested on-demand with the
1406 /dev/loop-control interface.
1410 mce [X86-32] Machine Check Exception
1412 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1414 md= [HW] RAID subsystems devices and level
1415 See Documentation/md.txt.
1418 Format: <first>,<last>
1419 Specifies range of consoles to be captured by the MDA.
1421 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1422 Amount of memory to be used when the kernel is not able
1423 to see the whole system memory or for test.
1424 [X86-32] Use together with memmap= to avoid physical
1425 address space collisions. Without memmap= PCI devices
1426 could be placed at addresses belonging to unused RAM.
1428 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1432 [KNL,SH] Allow user to override the default size for
1433 per-device physically contiguous DMA buffers.
1435 memmap=exactmap [KNL,X86] Enable setting of an exact
1436 E820 memory map, as specified by the user.
1437 Such memmap=exactmap lines can be constructed based on
1438 BIOS output or other requirements. See the memmap=nn@ss
1441 memmap=nn[KMG]@ss[KMG]
1442 [KNL] Force usage of a specific region of memory
1443 Region of memory to be used, from ss to ss+nn.
1445 memmap=nn[KMG]#ss[KMG]
1446 [KNL,ACPI] Mark specific memory as ACPI data.
1447 Region of memory to be used, from ss to ss+nn.
1449 memmap=nn[KMG]$ss[KMG]
1450 [KNL,ACPI] Mark specific memory as reserved.
1451 Region of memory to be used, from ss to ss+nn.
1452 Example: Exclude memory from 0x18690000-0x1869ffff
1453 memmap=64K$0x18690000
1455 memmap=0x10000$0x18690000
1457 memory_corruption_check=0/1 [X86]
1458 Some BIOSes seem to corrupt the first 64k of
1459 memory when doing things like suspend/resume.
1460 Setting this option will scan the memory
1461 looking for corruption. Enabling this will
1462 both detect corruption and prevent the kernel
1463 from using the memory being corrupted.
1464 However, its intended as a diagnostic tool; if
1465 repeatable BIOS-originated corruption always
1466 affects the same memory, you can use memmap=
1467 to prevent the kernel from using that memory.
1469 memory_corruption_check_size=size [X86]
1470 By default it checks for corruption in the low
1471 64k, making this memory unavailable for normal
1472 use. Use this parameter to scan for
1473 corruption in more or less memory.
1475 memory_corruption_check_period=seconds [X86]
1476 By default it checks for corruption every 60
1477 seconds. Use this parameter to check at some
1478 other rate. 0 disables periodic checking.
1480 memtest= [KNL,X86] Enable memtest
1482 default : 0 <disable>
1483 Specifies the number of memtest passes to be
1484 performed. Each pass selects another test
1485 pattern from a given set of patterns. Memtest
1486 fills the memory with this pattern, validates
1487 memory contents and reserves bad memory
1488 regions that are detected.
1490 meye.*= [HW] Set MotionEye Camera parameters
1491 See Documentation/video4linux/meye.txt.
1493 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1494 Multi-Function General Purpose Timers on AMD Geode
1497 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1498 the BIOS has incorrectly applied a workaround. TinyBIOS
1499 version 0.98 is known to be affected, 0.99 fixes the
1500 problem by letting the user disable the workaround.
1504 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1505 physical address is ignored.
1507 mini2440= [ARM,HW,KNL]
1508 Format:[0..2][b][c][t]
1510 MINI2440 configuration specification:
1511 0 - The attached screen is the 3.5" TFT
1512 1 - The attached screen is the 7" TFT
1513 2 - The VGA Shield is attached (1024x768)
1514 Leaving out the screen size parameter will not load
1515 the TFT driver, and the framebuffer will be left
1517 b - Enable backlight. The TFT backlight pin will be
1518 linked to the kernel VESA blanking code and a GPIO
1519 LED. This parameter is not necessary when using the
1521 c - Enable the s3c camera interface.
1522 t - Reserved for enabling touchscreen support. The
1523 touchscreen support is not enabled in the mainstream
1524 kernel as of 2.6.30, a preliminary port can be found
1525 in the "bleeding edge" mini2440 support kernel at
1526 http://repo.or.cz/w/linux-2.6/mini2440.git
1529 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1530 parameter allows control of the logging verbosity for
1531 the additional memory initialisation checks. A value
1532 of 0 disables mminit logging and a level of 4 will
1533 log everything. Information is printed at KERN_DEBUG
1534 so loglevel=8 may also need to be specified.
1537 [MOUSE] Maximum time between finger touching and
1538 leaving touchpad surface for touch to be considered
1539 a tap and be reported as a left button click (for
1540 touchpads working in absolute mode only).
1542 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1543 reporting absolute coordinates, such as tablets
1544 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1545 reporting absolute coordinates, such as tablets
1547 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1548 is similar to kernelcore except it specifies the
1549 amount of memory used for migratable allocations.
1550 If both kernelcore and movablecore is specified,
1551 then kernelcore will be at *least* the specified
1552 value but may be more. If movablecore on its own
1553 is specified, the administrator must be careful
1554 that the amount of memory usable for all allocations
1557 MTD_Partition= [MTD]
1558 Format: <name>,<region-number>,<size>,<offset>
1560 MTD_Region= [MTD] Format:
1561 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1564 See drivers/mtd/cmdlinepart.c.
1566 multitce=off [PPC] This parameter disables the use of the pSeries
1567 firmware feature for updating multiple TCE entries
1570 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1572 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1574 boundary - index of last SLC block on Flex-OneNAND.
1575 The remaining blocks are configured as MLC blocks.
1576 lock - Configure if Flex-OneNAND boundary should be locked.
1577 Once locked, the boundary cannot be changed.
1578 1 indicates lock status, 0 indicates unlock status.
1581 ARM/S3C2412 JIVE boot control
1583 See arch/arm/mach-s3c2412/mach-jive.c
1585 mtouchusb.raw_coordinates=
1586 [HW] Make the MicroTouch USB driver use raw coordinates
1587 ('y', default) or cooked coordinates ('n')
1589 mtrr_chunk_size=nn[KMG] [X86]
1590 used for mtrr cleanup. It is largest continuous chunk
1591 that could hold holes aka. UC entries.
1593 mtrr_gran_size=nn[KMG] [X86]
1594 Used for mtrr cleanup. It is granularity of mtrr block.
1596 Large value could prevent small alignment from
1599 mtrr_spare_reg_nr=n [X86]
1601 Range: 0,7 : spare reg number
1603 Used for mtrr cleanup. It is spare mtrr entries number.
1604 Set to 2 or more if your graphical card needs more.
1606 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1608 netdev= [NET] Network devices parameters
1609 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1610 Note that mem_start is often overloaded to mean
1611 something different and driver-specific.
1612 This usage is only documented in each driver source
1616 [NETFILTER] Enable connection tracking flow accounting
1617 0 to disable accounting
1618 1 to enable accounting
1621 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1622 See Documentation/filesystems/nfs/nfsroot.txt.
1624 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1625 See Documentation/filesystems/nfs/nfsroot.txt.
1627 nfsrootdebug [NFS] enable nfsroot debugging messages.
1628 See Documentation/filesystems/nfs/nfsroot.txt.
1630 nfs.callback_tcpport=
1631 [NFS] set the TCP port on which the NFSv4 callback
1632 channel should listen.
1635 [NFS] sets the pathname to the program which is used
1636 to update the NFS client cache entries.
1638 nfs.cache_getent_timeout=
1639 [NFS] sets the timeout after which an attempt to
1640 update a cache entry is deemed to have failed.
1642 nfs.idmap_cache_timeout=
1643 [NFS] set the maximum lifetime for idmapper cache
1647 [NFS] enable 64-bit inode numbers.
1648 If zero, the NFS client will fake up a 32-bit inode
1649 number for the readdir() and stat() syscalls instead
1650 of returning the full 64-bit number.
1651 The default is to return 64-bit inode numbers.
1653 nfs.nfs4_disable_idmapping=
1654 [NFSv4] When set, this option disables the NFSv4
1655 idmapper on the client, but only if the mount
1656 is using the 'sec=sys' security flavour. This may
1657 make migration from legacy NFSv2/v3 systems easier
1658 provided that the server has the appropriate support.
1659 The default is to always enable NFSv4 idmapping.
1661 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1662 when a NMI is triggered.
1663 Format: [state][,regs][,debounce][,die]
1665 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1666 Format: [panic,][nopanic,][num]
1668 0 - turn nmi_watchdog off
1669 When panic is specified, panic when an NMI watchdog
1670 timeout occurs (or 'nopanic' to override the opposite
1672 This is useful when you use a panic=... timeout and
1673 need the box quickly up again.
1675 netpoll.carrier_timeout=
1676 [NET] Specifies amount of time (in seconds) that
1677 netpoll should wait for a carrier. By default netpoll
1680 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1681 emulation library even if a 387 maths coprocessor
1685 [HW] Never suspend the console
1686 Disable suspending of consoles during suspend and
1687 hibernate operations. Once disabled, debugging
1688 messages can reach various consoles while the rest
1689 of the system is being put to sleep (ie, while
1690 debugging driver suspend/resume hooks). This may
1691 not work reliably with all consoles, but is known
1692 to work with serial and VGA consoles.
1693 To facilitate more flexible debugging, we also add
1694 console_suspend, a printk module parameter to control
1695 it. Users could use console_suspend (usually
1696 /sys/module/printk/parameters/console_suspend) to
1697 turn on/off it dynamically.
1699 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1700 caches in the slab allocator. Saves per-node memory,
1701 but will impact performance.
1705 noapic [SMP,APIC] Tells the kernel to not make use of any
1706 IOAPICs that may be present in the system.
1708 noautogroup Disable scheduler automatic task group creation.
1710 nobats [PPC] Do not use BATs for mapping kernel lowmem
1711 on "Classic" PPC cores.
1715 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1717 nodelayacct [KNL] Disable per-task delay accounting
1719 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1721 nodsp [SH] Disable hardware DSP at boot time.
1723 noefi [X86] Disable EFI runtime services support.
1728 On X86-32 available only on PAE configured kernels.
1729 noexec=on: enable non-executable mappings (default)
1730 noexec=off: disable non-executable mappings
1733 Disable SMEP (Supervisor Mode Execution Protection)
1734 even if it is supported by processor.
1737 This affects only 32-bit executables.
1738 noexec32=on: enable non-executable mappings (default)
1739 read doesn't imply executable mappings
1740 noexec32=off: disable non-executable mappings
1741 read implies executable mappings
1743 nofpu [SH] Disable hardware FPU at boot time.
1745 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1746 register save and restore. The kernel will only save
1747 legacy floating-point registers on task switch.
1749 noxsave [BUGS=X86] Disables x86 extended register state save
1750 and restore using xsave. The kernel will fallback to
1751 enabling legacy floating-point and sse state.
1753 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1754 wfi(ARM) instruction doesn't work correctly and not to
1755 use it. This is also useful when using JTAG debugger.
1757 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1758 instruction doesn't work correctly and not to
1761 no_file_caps Tells the kernel not to honor file capabilities. The
1762 only way then for a file to be executed with privilege
1763 is to be setuid root or executed by root.
1765 nohalt [IA-64] Tells the kernel not to use the power saving
1766 function PAL_HALT_LIGHT when idle. This increases
1767 power-consumption. On the positive side, it reduces
1768 interrupt wake-up latency, which may improve performance
1769 in certain environments such as networked servers or
1772 nohz= [KNL] Boottime enable/disable dynamic ticks
1773 Valid arguments: on, off
1776 noiotrap [SH] Disables trapped I/O port accesses.
1778 noirqdebug [X86-32] Disables the code which attempts to detect and
1779 disable unhandled interrupt sources.
1781 no_timer_check [X86,APIC] Disables the code which tests for
1782 broken timer IRQ sources.
1784 noisapnp [ISAPNP] Disables ISA PnP code.
1786 noinitrd [RAM] Tells the kernel not to load any configured
1789 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1791 [Deprecated - use intremap=off]
1795 nojitter [IA-64] Disables jitter checking for ITC timers.
1797 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1799 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1802 no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
1803 steal time is computed, but won't influence scheduler
1806 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1808 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1810 noltlbs [PPC] Do not use large page/tlb entries for kernel
1811 lowmem mapping on PPC40x.
1813 nomca [IA-64] Disable machine check abort handling
1815 nomce [X86-32] Machine Check Exception
1817 nomfgpt [X86-32] Disable Multi-Function General Purpose
1818 Timer usage (for AMD Geode machines).
1820 nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
1821 shutdown the other cpus. Instead use the REBOOT_VECTOR
1824 nopat [X86] Disable PAT (page attribute table extension of
1825 pagetables) support.
1827 norandmaps Don't use address space randomization. Equivalent to
1828 echo 0 > /proc/sys/kernel/randomize_va_space
1830 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1832 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1833 with UP alternatives
1835 noresidual [PPC] Don't use residual data on PReP machines.
1837 nordrand [X86] Disable the direct use of the RDRAND
1838 instruction even if it is supported by the
1839 processor. RDRAND is still available to user
1842 noresume [SWSUSP] Disables resume and restores original swap
1845 no-scroll [VGA] Disables scrollback.
1846 This is required for the Braillex ib80-piezo Braille
1847 reader made by F.H. Papenmeier (Germany).
1851 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1853 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1854 and disable the IO APIC. legacy for "maxcpus=0".
1856 nosoftlockup [KNL] Disable the soft-lockup detector.
1858 nosync [HW,M68K] Disables sync negotiation for all devices.
1860 notsc [BUGS=X86-32] Disable Time Stamp Counter
1862 nousb [USB] Disable the USB subsystem
1864 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1868 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1870 nptcg= [IA-64] Override max number of concurrent global TLB
1871 purges which is reported from either PAL_VM_SUMMARY or
1874 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1875 could support. nr_cpus=n : n >= 1 limits the kernel to
1876 supporting 'n' processors. Later in runtime you can not
1877 use hotplug cpu feature to put more cpu back to online.
1878 just like you compile the kernel NR_CPUS=n
1880 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1882 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1883 one of ['zone', 'node', 'default'] can be specified
1884 This can be set from sysctl after boot.
1885 See Documentation/sysctl/vm.txt for details.
1887 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1888 See Documentation/debugging-via-ohci1394.txt for more
1891 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1892 Rather than timing out after 20 ms if an EC
1893 command is not properly ACKed, override the length
1894 of the timeout. We have interrupts disabled while
1895 waiting for the ACK, so if this is set too high
1896 interrupts *may* be lost!
1898 omap_mux= [OMAP] Override bootloader pin multiplexing.
1899 Format: <mux_mode0.mode_name=value>...
1900 For example, to override I2C bus2:
1901 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1903 oprofile.timer= [HW]
1904 Use timer interrupt instead of performance counters
1906 oprofile.cpu_type= Force an oprofile cpu type
1907 This might be useful if you have an older oprofile
1908 userland or if you want common events.
1909 Format: { arch_perfmon }
1910 arch_perfmon: [X86] Force use of architectural
1911 perfmon on Intel CPUs instead of the
1912 CPU specific event set.
1913 timer: [X86] Force use of architectural NMI
1914 timer mode (see also oprofile.timer
1915 for generic hr timer mode)
1916 [s390] Force legacy basic mode sampling
1917 (report cpu_type "timer")
1919 oops=panic Always panic on oopses. Default is to just kill the
1920 process, but there is a small probability of
1921 deadlocking the machine.
1922 This will also cause panics on machine check exceptions.
1923 Useful together with panic=30 to trigger a reboot.
1926 See Documentation/sound/oss/oss-parameters.txt
1928 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1929 timeout > 0: seconds before rebooting
1930 timeout = 0: wait forever
1931 timeout < 0: reboot immediately
1934 parkbd.port= [HW] Parallel port number the keyboard adapter is
1935 connected to, default is 0.
1937 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1938 0 for XT, 1 for AT (default is AT).
1941 parport= [HW,PPT] Specify parallel ports. 0 disables.
1942 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1943 Use 'auto' to force the driver to use any
1944 IRQ/DMA settings detected (the default is to
1945 ignore detected IRQ/DMA settings because of
1946 possible conflicts). You can specify the base
1947 address, IRQ, and DMA settings; IRQ and DMA
1948 should be numbers, or 'auto' (for using detected
1949 settings on that particular port), or 'nofifo'
1950 (to avoid using a FIFO even if it is detected).
1951 Parallel ports are assigned in the order they
1952 are specified on the command line, starting
1955 parport_init_mode= [HW,PPT]
1956 Configure VIA parallel port to operate in
1957 a specific mode. This is necessary on Pegasos
1958 computer where firmware has no options for setting
1959 up parallel port mode and sets it to spp.
1960 Currently this function knows 686a and 8231 chips.
1961 Format: [spp|ps2|epp|ecp|ecpepp]
1964 Halt all CPUs after the first oops has been printed for
1965 the specified number of seconds. This is to be used if
1966 your oopses keep scrolling off the screen.
1971 See header of drivers/block/paride/pcd.c.
1972 See also Documentation/blockdev/paride.txt.
1974 pci=option[,option...] [PCI] various PCI subsystem options:
1975 earlydump [X86] dump PCI config space before the kernel
1977 off [X86] don't probe for the PCI bus
1978 bios [X86-32] force use of PCI BIOS, don't access
1979 the hardware directly. Use this if your machine
1980 has a non-standard PCI host bridge.
1981 nobios [X86-32] disallow use of PCI BIOS, only direct
1982 hardware access methods are allowed. Use this
1983 if you experience crashes upon bootup and you
1984 suspect they are caused by the BIOS.
1985 conf1 [X86] Force use of PCI Configuration
1987 conf2 [X86] Force use of PCI Configuration
1989 noaer [PCIE] If the PCIEAER kernel config parameter is
1990 enabled, this kernel boot option can be used to
1991 disable the use of PCIE advanced error reporting.
1992 nodomains [PCI] Disable support for multiple PCI
1993 root domains (aka PCI segments, in ACPI-speak).
1994 nommconf [X86] Disable use of MMCONFIG for PCI
1996 check_enable_amd_mmconf [X86] check for and enable
1997 properly configured MMIO access to PCI
1998 config space on AMD family 10h CPU
1999 nomsi [MSI] If the PCI_MSI kernel config parameter is
2000 enabled, this kernel boot option can be used to
2001 disable the use of MSI interrupts system-wide.
2002 noioapicquirk [APIC] Disable all boot interrupt quirks.
2003 Safety option to keep boot IRQs enabled. This
2004 should never be necessary.
2005 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
2006 primary IO-APIC for bridges that cannot disable
2007 boot IRQs. This fixes a source of spurious IRQs
2008 when the system masks IRQs.
2009 noioapicreroute [APIC] Disable workaround that uses the
2010 boot IRQ equivalent of an IRQ that connects to
2011 a chipset where boot IRQs cannot be disabled.
2012 The opposite of ioapicreroute.
2013 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
2014 routing table. These calls are known to be buggy
2015 on several machines and they hang the machine
2016 when used, but on other computers it's the only
2017 way to get the interrupt routing table. Try
2018 this option if the kernel is unable to allocate
2019 IRQs or discover secondary PCI buses on your
2021 rom [X86] Assign address space to expansion ROMs.
2022 Use with caution as certain devices share
2023 address decoders between ROMs and other
2025 norom [X86] Do not assign address space to
2026 expansion ROMs that do not already have
2027 BIOS assigned address ranges.
2028 nobar [X86] Do not assign address space to the
2029 BARs that weren't assigned by the BIOS.
2030 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
2031 assigned automatically to PCI devices. You can
2032 make the kernel exclude IRQs of your ISA cards
2034 pirqaddr=0xAAAAA [X86] Specify the physical address
2035 of the PIRQ table (normally generated
2036 by the BIOS) if it is outside the
2037 F0000h-100000h range.
2038 lastbus=N [X86] Scan all buses thru bus #N. Can be
2039 useful if the kernel is unable to find your
2040 secondary buses and you want to tell it
2041 explicitly which ones they are.
2042 assign-busses [X86] Always assign all PCI bus
2043 numbers ourselves, overriding
2044 whatever the firmware may have done.
2045 usepirqmask [X86] Honor the possible IRQ mask stored
2046 in the BIOS $PIR table. This is needed on
2047 some systems with broken BIOSes, notably
2048 some HP Pavilion N5400 and Omnibook XE3
2049 notebooks. This will have no effect if ACPI
2050 IRQ routing is enabled.
2051 noacpi [X86] Do not use ACPI for IRQ routing
2052 or for PCI scanning.
2053 use_crs [X86] Use PCI host bridge window information
2054 from ACPI. On BIOSes from 2008 or later, this
2055 is enabled by default. If you need to use this,
2056 please report a bug.
2057 nocrs [X86] Ignore PCI host bridge windows from ACPI.
2058 If you need to use this, please report a bug.
2059 routeirq Do IRQ routing for all PCI devices.
2060 This is normally done in pci_enable_device(),
2061 so this option is a temporary workaround
2062 for broken drivers that don't call it.
2063 skip_isa_align [X86] do not align io start addr, so can
2064 handle more pci cards
2065 firmware [ARM] Do not re-enumerate the bus but instead
2066 just use the configuration from the
2067 bootloader. This is currently used on
2068 IXP2000 systems where the bus has to be
2069 configured a certain way for adjunct CPUs.
2070 noearly [X86] Don't do any early type 1 scanning.
2071 This might help on some broken boards which
2072 machine check when some devices' config space
2073 is read. But various workarounds are disabled
2074 and some IOMMU drivers will not work.
2075 bfsort Sort PCI devices into breadth-first order.
2076 This sorting is done to get a device
2077 order compatible with older (<= 2.4) kernels.
2078 nobfsort Don't sort PCI devices into breadth-first order.
2079 cbiosize=nn[KMG] The fixed amount of bus space which is
2080 reserved for the CardBus bridge's IO window.
2081 The default value is 256 bytes.
2082 cbmemsize=nn[KMG] The fixed amount of bus space which is
2083 reserved for the CardBus bridge's memory
2084 window. The default value is 64 megabytes.
2087 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2088 Specifies alignment and device to reassign
2089 aligned memory resources.
2090 If <order of align> is not specified,
2091 PAGE_SIZE is used as alignment.
2092 PCI-PCI bridge can be specified, if resource
2093 windows need to be expanded.
2094 ecrc= Enable/disable PCIe ECRC (transaction layer
2095 end-to-end CRC checking).
2096 bios: Use BIOS/firmware settings. This is the
2100 realloc reallocate PCI resources if allocations done by BIOS
2103 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2106 force Enable ASPM even on devices that claim not to support it.
2107 WARNING: Forcing ASPM on may cause system lockups.
2109 pcie_ports= [PCIE] PCIe ports handling:
2110 auto Ask the BIOS whether or not to use native PCIe services
2111 associated with PCIe ports (PME, hot-plug, AER). Use
2112 them only if that is allowed by the BIOS.
2113 native Use native PCIe services associated with PCIe ports
2115 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2118 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2119 nomsi Do not use MSI for native PCIe PME signaling (this makes
2120 all PCIe root ports use INTx for all services).
2122 pcmv= [HW,PCMCIA] BadgePAD 4
2125 See Documentation/blockdev/paride.txt.
2127 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2130 See arch/parisc/kernel/pdc_chassis.c
2132 percpu_alloc= Select which percpu first chunk allocator to use.
2133 Currently supported values are "embed" and "page".
2134 Archs may support subset or none of the selections.
2135 See comments in mm/percpu.c for details on each
2136 allocator. This parameter is primarily for debugging
2137 and performance comparison.
2140 See Documentation/blockdev/paride.txt.
2143 See Documentation/blockdev/paride.txt.
2145 pirq= [SMP,APIC] Manual mp-table setup
2146 See Documentation/x86/i386/IO-APIC.txt.
2148 plip= [PPT,NET] Parallel port network link
2149 Format: { parport<nr> | timid | 0 }
2150 See also Documentation/parport.txt.
2152 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2153 Override pmtimer IOPort with a hex value.
2157 Enable PNP debug messages (depends on the
2158 CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
2159 via /sys/module/pnp/parameters/debug. We always show
2160 current resource usage; turning this on also shows
2161 possible settings and some assignment information.
2167 { on | off | curr | res | no-curr | no-res }
2170 [ISAPNP] Exclude IRQs for the autoconfiguration
2173 [ISAPNP] Exclude DMAs for the autoconfiguration
2175 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2176 Ranges are in pairs (I/O port base and size).
2179 [ISAPNP] Exclude memory regions for the
2181 Ranges are in pairs (memory base and size).
2183 ports= [IP_VS_FTP] IPVS ftp helper module
2185 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2187 Format: <port>,<port>....
2189 print-fatal-signals=
2190 [KNL] debug: print fatal signals
2192 If enabled, warn about various signal handling
2193 related application anomalies: too many signals,
2194 too many POSIX.1 timers, fatal signals causing a
2197 If you hit the warning due to signal overflow,
2198 you might want to try "ulimit -i unlimited".
2202 printk.time= Show timing data prefixed to each printk message line
2203 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2205 processor.max_cstate= [HW,ACPI]
2206 Limit processor to maximum C-state
2207 max_cstate=9 overrides any DMI blacklist limit.
2209 processor.nocst [HW,ACPI]
2210 Ignore the _CST method to determine C-states,
2211 instead using the legacy FADT method
2213 profile= [KNL] Enable kernel profiling via /proc/profile
2214 Format: [schedule,]<number>
2215 Param: "schedule" - profile schedule points.
2216 Param: <number> - step/bucket size as a power of 2 for
2217 statistical time based profiling.
2218 Param: "sleep" - profile D-state sleeping (millisecs).
2219 Requires CONFIG_SCHEDSTATS
2220 Param: "kvm" - profile VM exits.
2222 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2224 See Documentation/blockdev/ramdisk.txt.
2226 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2227 probe for; one of (bare|imps|exps|lifebook|any).
2228 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2230 psmouse.resetafter= [HW,MOUSE]
2231 Try to reset the device after so many bad packets
2234 [HW,MOUSE] Set desired mouse resolution, in dpi.
2235 psmouse.smartscroll=
2236 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2237 0 = disabled, 1 = enabled (default).
2239 pstore.backend= Specify the name of the pstore backend to use
2242 See Documentation/blockdev/paride.txt.
2245 [KNL] Number of legacy pty's. Overwrites compiled-in
2248 quiet [KNL] Disable most log messages
2253 See Documentation/md.txt.
2255 ramdisk_blocksize= [RAM]
2256 See Documentation/blockdev/ramdisk.txt.
2258 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2259 See Documentation/blockdev/ramdisk.txt.
2261 rcupdate.blimit= [KNL,BOOT]
2262 Set maximum number of finished RCU callbacks to process
2265 rcupdate.qhimark= [KNL,BOOT]
2266 Set threshold of queued
2267 RCU callbacks over which batch limiting is disabled.
2269 rcupdate.qlowmark= [KNL,BOOT]
2270 Set threshold of queued RCU callbacks below which
2271 batch limiting is re-enabled.
2275 Run specified binary instead of /init from the ramdisk,
2276 used for early userspace startup. See initrd.
2278 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2279 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2280 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2283 [KNL, SMP] Set scheduler's default relax_domain_level.
2284 See Documentation/cgroups/cpusets.txt.
2286 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2288 reservetop= [X86-32]
2290 Reserves a hole at the top of the kernel virtual
2295 Set the amount of memory to reserve for BIOS at
2296 the bottom of the address space.
2298 reset_devices [KNL] Force drivers to reset the underlying device
2299 during initialization.
2302 Specify the partition device for software suspend
2304 resume_offset= [SWSUSP]
2305 Specify the offset from the beginning of the partition
2306 given by "resume=" at which the swap header is located,
2307 in <PAGE_SIZE> units (needed only for swap files).
2308 See Documentation/power/swsusp-and-swap-files.txt
2310 resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
2311 read the resume files
2313 resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
2314 Useful for devices that are detected asynchronously
2315 (e.g. USB and MMC devices).
2317 hibernate= [HIBERNATION]
2318 noresume Don't check if there's a hibernation image
2319 present during boot.
2320 nocompress Don't compress/decompress hibernation images.
2322 retain_initrd [RAM] Keep initrd memory after extraction
2324 rhash_entries= [KNL,NET]
2325 Set number of hash buckets for route cache
2327 riscom8= [HW,SERIAL]
2328 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2330 ro [KNL] Mount root device read-only on boot
2332 root= [KNL] Root filesystem
2333 See name_to_dev_t comment in init/do_mounts.c.
2335 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2336 mount the root filesystem
2338 rootflags= [KNL] Set root filesystem mount option string
2340 rootfstype= [KNL] Set root filesystem type
2342 rootwait [KNL] Wait (indefinitely) for root device to show up.
2343 Useful for devices that are detected asynchronously
2344 (e.g. USB and MMC devices).
2346 rw [KNL] Mount root device read-write on boot
2348 S [KNL] Run init in single mode
2351 See drivers/net/irda/sa1100_ir.c.
2353 sbni= [NET] Granch SBNI12 leased line adapter
2355 sched_debug [KNL] Enables verbose scheduler debug messages.
2357 security= [SECURITY] Choose a security module to enable at boot.
2358 If this boot parameter is not specified, only the first
2359 security module asking for security registration will be
2360 loaded. An invalid security module name will be treated
2361 as if no module has been chosen.
2363 selinux= [SELINUX] Disable or enable SELinux at boot time.
2364 Format: { "0" | "1" }
2365 See security/selinux/Kconfig help text.
2368 Default value is set via kernel config option.
2369 If enabled at boot time, /selinux/disable can be used
2370 later to disable prior to initial policy load.
2372 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2373 Format: { "0" | "1" }
2374 See security/apparmor/Kconfig help text
2377 Default value is set via kernel config option.
2379 serialnumber [BUGS=X86-32]
2382 Maximal number of shapers.
2384 show_msr= [x86] show boot-time MSR settings
2385 Format: { <integer> }
2386 Show boot-time (BIOS-initialized) MSR settings.
2387 The parameter means the number of CPUs to show,
2388 for example 1 means boot CPU only.
2395 slab_max_order= [MM, SLAB]
2396 Determines the maximum allowed order for slabs.
2397 A high setting may cause OOMs due to memory
2398 fragmentation. Defaults to 1 for systems with
2399 more than 32MB of RAM, 0 otherwise.
2401 slub_debug[=options[,slabs]] [MM, SLUB]
2402 Enabling slub_debug allows one to determine the
2403 culprit if slab objects become corrupted. Enabling
2404 slub_debug can create guard zones around objects and
2405 may poison objects when not in use. Also tracks the
2406 last alloc / free. For more information see
2407 Documentation/vm/slub.txt.
2409 slub_max_order= [MM, SLUB]
2410 Determines the maximum allowed order for slabs.
2411 A high setting may cause OOMs due to memory
2412 fragmentation. For more information see
2413 Documentation/vm/slub.txt.
2415 slub_min_objects= [MM, SLUB]
2416 The minimum number of objects per slab. SLUB will
2417 increase the slab order up to slub_max_order to
2418 generate a sufficiently large slab able to contain
2419 the number of objects indicated. The higher the number
2420 of objects the smaller the overhead of tracking slabs
2421 and the less frequently locks need to be acquired.
2422 For more information see Documentation/vm/slub.txt.
2424 slub_min_order= [MM, SLUB]
2425 Determines the mininum page order for slabs. Must be
2426 lower than slub_max_order.
2427 For more information see Documentation/vm/slub.txt.
2429 slub_nomerge [MM, SLUB]
2430 Disable merging of slabs with similar size. May be
2431 necessary if there is some reason to distinguish
2432 allocs to different slabs. Debug options disable
2433 merging on their own.
2434 For more information see Documentation/vm/slub.txt.
2437 Format: <io1>[,<io2>[,...,<io8>]]
2439 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2440 attempt to substitute SMP alternatives once at boot.
2442 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2443 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2444 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2445 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2446 smsc-ircc2.ircc_irq= [HW] IRQ line
2447 smsc-ircc2.ircc_dma= [HW] DMA channel
2448 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2449 0: Toshiba Satellite 1800 (GP data pin select)
2450 1: Fast pin select (default)
2454 [KNL] Should the soft-lockup detector generate panics.
2457 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2458 See Documentation/laptops/sonypi.txt
2460 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2461 See Documentation/serial/specialix.txt.
2463 spia_io_base= [HW,MTD]
2469 Enabled the stack tracer on boot up.
2473 Set the STI (builtin display/keyboard on the HP-PARISC
2474 machines) console (graphic card) which should be used
2475 as the initial boot-console.
2476 See also comment in drivers/video/console/sticore.c.
2479 See comment in drivers/video/console/sticore.c.
2482 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2484 sunrpc.min_resvport=
2485 sunrpc.max_resvport=
2487 SunRPC servers often require that client requests
2488 originate from a privileged port (i.e. a port in the
2489 range 0 < portnr < 1024).
2490 An administrator who wishes to reserve some of these
2491 ports for other uses may adjust the range that the
2492 kernel's sunrpc client considers to be privileged
2493 using these two parameters to set the minimum and
2494 maximum port values.
2498 Control how the NFS server code allocates CPUs to
2499 service thread pools. Depending on how many NICs
2500 you have and where their interrupts are bound, this
2501 option will affect which CPUs will do NFS serving.
2502 Note: this parameter cannot be changed while the
2503 NFS server is running.
2505 auto the server chooses an appropriate mode
2506 automatically using heuristics
2507 global a single global pool contains all CPUs
2508 percpu one pool for each CPU
2509 pernode one pool for each NUMA node (equivalent
2510 to global on non-NUMA machines)
2512 sunrpc.tcp_slot_table_entries=
2513 sunrpc.udp_slot_table_entries=
2515 Sets the upper limit on the number of simultaneous
2516 RPC calls that can be sent from the client to a
2517 server. Increasing these values may allow you to
2518 improve throughput, but will also increase the
2519 amount of memory reserved for use by the client.
2522 [KNL] Enable accounting of swap in memory resource
2523 controller if no parameter or 1 is given or disable
2524 it if 0 is given (See Documentation/cgroups/memory.txt)
2526 swiotlb= [IA-64] Number of I/O TLB slabs
2530 sysfs.deprecated=0|1 [KNL]
2531 Enable/disable old style sysfs layout for old udev
2532 on older distributions. When this option is enabled
2533 very new udev will not work anymore. When this option
2534 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2535 in older udev will not work anymore.
2536 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2537 the kernel configuration.
2539 sysrq_always_enabled
2541 Ignore sysrq setting - this boot parameter will
2542 neutralize any effect of /proc/sys/kernel/sysrq.
2543 Useful for debugging.
2547 test_suspend= [SUSPEND]
2548 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2549 standby suspend) as the system sleep state to briefly
2550 enter during system startup. The system is woken from
2551 this state using a wakeup-capable RTC alarm.
2553 thash_entries= [KNL,NET]
2554 Set number of hash buckets for TCP connection
2556 thermal.act= [HW,ACPI]
2557 -1: disable all active trip points in all thermal zones
2558 <degrees C>: override all lowest active trip points
2560 thermal.crt= [HW,ACPI]
2561 -1: disable all critical trip points in all thermal zones
2562 <degrees C>: override all critical trip points
2564 thermal.nocrt= [HW,ACPI]
2565 Set to disable actions on ACPI thermal zone
2566 critical and hot trip points.
2568 thermal.off= [HW,ACPI]
2569 1: disable ACPI thermal control
2571 thermal.psv= [HW,ACPI]
2572 -1: disable all passive trip points
2573 <degrees C>: override all passive trip points to this
2576 thermal.tzp= [HW,ACPI]
2577 Specify global default ACPI thermal zone polling rate
2578 <deci-seconds>: poll all this frequency
2579 0: no polling (default)
2582 Force threading of all interrupt handlers except those
2583 marked explicitely IRQF_NO_THREAD.
2587 Specify if the kernel should make use of the cpu
2588 topology information if the hardware supports this.
2589 The scheduler will make use of this information and
2590 e.g. base its process migration decisions on it.
2595 tpm_suspend_pcr=[HW,TPM]
2596 Format: integer pcr id
2597 Specify that at suspend time, the tpm driver
2598 should extend the specified pcr with zeros,
2599 as a workaround for some chips which fail to
2600 flush the last written pcr on TPM_SaveState.
2601 This will guarantee that all the other pcrs
2604 trace_buf_size=nn[KMG]
2605 [FTRACE] will set tracing buffer size.
2607 trace_event=[event-list]
2608 [FTRACE] Set and start specified trace events in order
2609 to facilitate early boot debugging.
2610 See also Documentation/trace/events.txt
2612 tsc= Disable clocksource stability checks for TSC.
2614 [x86] reliable: mark tsc clocksource as reliable, this
2615 disables clocksource verification at runtime, as well
2616 as the stability checks done at bootup. Used to enable
2617 high-resolution timer mode on older hardware, and in
2618 virtualized environment.
2619 [x86] noirqtime: Do not use TSC to do irq accounting.
2620 Used to run time disable IRQ_TIME_ACCOUNTING on any
2621 platforms where RDTSC is slow and this accounting
2624 turbografx.map[2|3]= [HW,JOY]
2625 TurboGraFX parallel port interface
2627 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2628 See also Documentation/input/joystick-parport.txt
2630 udbg-immortal [PPC] When debugging early kernel crashes that
2631 happen after console_init() and before a proper
2632 console driver takes over, this boot options might
2633 help "seeing" what's going on.
2635 uhash_entries= [KNL,NET]
2636 Set number of hash buckets for UDP/UDP-Lite connections
2639 [USB] Ignore overcurrent events (default N).
2640 Some badly-designed motherboards generate lots of
2641 bogus events, for ports that aren't wired to
2642 anything. Set this parameter to avoid log spamming.
2643 Note that genuine overcurrent events won't be
2647 [X86] Cause panic on unknown NMI.
2649 usbcore.authorized_default=
2650 [USB] Default USB device authorization:
2651 (default -1 = authorized except for wireless USB,
2652 0 = not authorized, 1 = authorized)
2654 usbcore.autosuspend=
2655 [USB] The autosuspend time delay (in seconds) used
2656 for newly-detected USB devices (default 2). This
2657 is the time required before an idle device will be
2658 autosuspended. Devices for which the delay is set
2659 to a negative value won't be autosuspended at all.
2661 usbcore.usbfs_snoop=
2662 [USB] Set to log all usbfs traffic (default 0 = off).
2664 usbcore.blinkenlights=
2665 [USB] Set to cycle leds on hubs (default 0 = off).
2667 usbcore.old_scheme_first=
2668 [USB] Start with the old device initialization
2669 scheme (default 0 = off).
2671 usbcore.usbfs_memory_mb=
2672 [USB] Memory limit (in MB) for buffers allocated by
2673 usbfs (default = 16, 0 = max = 2047).
2675 usbcore.use_both_schemes=
2676 [USB] Try the other device initialization scheme
2677 if the first one fails (default 1 = enabled).
2679 usbcore.initial_descriptor_timeout=
2680 [USB] Specifies timeout for the initial 64-byte
2681 USB_REQ_GET_DESCRIPTOR request in milliseconds
2682 (default 5000 = 5.0 seconds).
2685 [USBHID] The interval which mice are to be polled at.
2687 usb-storage.delay_use=
2688 [UMS] The delay in seconds before a new device is
2689 scanned for Logical Units (default 5).
2692 [UMS] A list of quirks entries to supplement or
2693 override the built-in unusual_devs list. List
2694 entries are separated by commas. Each entry has
2695 the form VID:PID:Flags where VID and PID are Vendor
2696 and Product ID values (4-digit hex numbers) and
2697 Flags is a set of characters, each corresponding
2698 to a common usb-storage quirk flag as follows:
2699 a = SANE_SENSE (collect more than 18 bytes
2701 b = BAD_SENSE (don't collect more than 18
2702 bytes of sense data);
2703 c = FIX_CAPACITY (decrease the reported
2704 device capacity by one sector);
2705 d = NO_READ_DISC_INFO (don't use
2706 READ_DISC_INFO command);
2707 e = NO_READ_CAPACITY_16 (don't use
2708 READ_CAPACITY_16 command);
2709 h = CAPACITY_HEURISTICS (decrease the
2710 reported device capacity by one
2711 sector if the number is odd);
2712 i = IGNORE_DEVICE (don't bind to this
2714 l = NOT_LOCKABLE (don't try to lock and
2715 unlock ejectable media);
2716 m = MAX_SECTORS_64 (don't transfer more
2717 than 64 sectors = 32 KB at a time);
2718 n = INITIAL_READ10 (force a retry of the
2719 initial READ(10) command);
2720 o = CAPACITY_OK (accept the capacity
2721 reported by the device);
2722 r = IGNORE_RESIDUE (the device reports
2723 bogus residue values);
2724 s = SINGLE_LUN (the device has only one
2726 w = NO_WP_DETECT (don't test whether the
2727 medium is write-protected).
2728 Example: quirks=0419:aaf5:rl,0421:0433:rc
2730 user_debug= [KNL,ARM]
2732 See arch/arm/Kconfig.debug help text.
2733 1 - undefined instruction events
2735 4 - invalid data aborts
2738 Example: user_debug=31
2741 [X86] Flags controlling user PTE allocations.
2743 nohigh = do not allocate PTE pages in
2744 HIGHMEM regardless of setting
2748 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2749 vdso=1: enable VDSO (default)
2750 vdso=0: disable VDSO mapping
2753 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2754 vdso32=1: enable 32-bit VDSO (default)
2755 vdso32=0: disable 32-bit VDSO mapping
2758 vector=percpu: enable percpu vector domain
2760 video= [FB] Frame buffer configuration
2761 See Documentation/fb/modedb.txt.
2763 vga= [BOOT,X86-32] Select a particular video mode
2764 See Documentation/x86/boot.txt and
2765 Documentation/svga.txt.
2766 Use vga=ask for menu.
2767 This is actually a boot loader parameter; the value is
2768 passed to the kernel using a special protocol.
2770 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2771 size of <nn>. This can be used to increase the
2772 minimum size (128MB on x86). It can also be used to
2773 decrease the size and leave more room for directly
2776 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2779 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2782 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2786 Controls the behavior of vsyscalls (i.e. calls to
2787 fixed addresses of 0xffffffffff600x00 from legacy
2788 code). Most statically-linked binaries and older
2789 versions of glibc use these calls. Because these
2790 functions are at fixed addresses, they make nice
2791 targets for exploits that can control RIP.
2793 emulate [default] Vsyscalls turn into traps and are
2794 emulated reasonably safely.
2796 native Vsyscalls are native syscall instructions.
2797 This is a little bit faster than trapping
2798 and makes a few dynamic recompilers work
2799 better than they would in emulation mode.
2800 It also makes exploits much easier to write.
2802 none Vsyscalls don't work at all. This makes
2803 them quite hard to use for exploits but
2804 might break your system.
2806 vt.cur_default= [VT] Default cursor shape.
2807 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2808 the parameters of the <Esc>[?A;B;Cc escape sequence;
2809 see VGA-softcursor.txt. Default: 2 = underline.
2811 vt.default_blu= [VT]
2812 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2813 Change the default blue palette of the console.
2814 This is a 16-member array composed of values
2817 vt.default_grn= [VT]
2818 Format: <green0>,<green1>,<green2>,...,<green15>
2819 Change the default green palette of the console.
2820 This is a 16-member array composed of values
2823 vt.default_red= [VT]
2824 Format: <red0>,<red1>,<red2>,...,<red15>
2825 Change the default red palette of the console.
2826 This is a 16-member array composed of values
2832 Set system-wide default UTF-8 mode for all tty's.
2833 Default is 1, i.e. UTF-8 mode is enabled for all
2834 newly opened terminals.
2836 vt.global_cursor_default=
2839 Set system-wide default for whether a cursor
2840 is shown on new VTs. Default is -1,
2841 i.e. cursors will be created by default unless
2842 overridden by individual drivers. 0 will hide
2843 cursors, 1 will display them.
2845 watchdog timers [HW,WDT] For information on watchdog timers,
2846 see Documentation/watchdog/watchdog-parameters.txt
2847 or other driver-specific files in the
2848 Documentation/watchdog/ directory.
2850 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2851 default x2apic cluster mode on platforms
2854 x86_mrst_timer= [X86-32,APBT]
2855 Choose timer option for x86 Moorestown MID platform.
2856 Two valid options are apbt timer only and lapic timer
2857 plus one apbt timer for broadcast timer.
2858 x86_mrst_timer=apbt_only | lapic_and_apbt
2860 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2861 xd_geo= See header of drivers/block/xd.c.
2863 xen_emul_unplug= [HW,X86,XEN]
2864 Unplug Xen emulated devices
2865 Format: [unplug0,][unplug1]
2866 ide-disks -- unplug primary master IDE devices
2867 aux-ide-disks -- unplug non-primary-master IDE devices
2868 nics -- unplug network devices
2869 all -- unplug all emulated devices (NICs and IDE disks)
2870 unnecessary -- unplugging emulated devices is
2871 unnecessary even if the host did not respond to
2873 never -- do not unplug even if version check succeeds
2875 xirc2ps_cs= [NET,PCMCIA]
2877 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2879 ______________________________________________________________________
2883 Add more DRM drivers.
projects / karo-tx-linux.git / blob