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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
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 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AX25 Appropriate AX.25 support is enabled.
38 BLACKFIN Blackfin architecture is enabled.
39 DRM Direct Rendering Management support is enabled.
40 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
41 EFI EFI Partitioning (GPT) is enabled
42 EIDE EIDE/ATAPI support is enabled.
43 FB The frame buffer device is enabled.
44 HW Appropriate hardware is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LIBATA Libata driver is enabled
52 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
60 MSI Message Signaled Interrupts (PCI).
61 MTD MTD (Memory Technology Device) support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
64 GENERIC_TIME The generic timeofday code is enabled.
65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PV_OPS A paravirtualized kernel is enabled.
68 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCIE PCI Express support is enabled.
72 PCMCIA The PCMCIA subsystem is enabled.
73 PNP Plug & Play support is enabled.
74 PPC PowerPC architecture is enabled.
75 PPT Parallel port support is enabled.
76 PS2 Appropriate PS/2 support is enabled.
77 RAM RAM disk support is enabled.
78 ROOTPLUG The example Root Plug LSM is enabled.
79 S390 S390 architecture is enabled.
80 SCSI Appropriate SCSI support is enabled.
81 A lot of drivers has their options described inside of
82 Documentation/scsi/.
83 SECURITY Different security models are enabled.
84 SELINUX SELinux support is enabled.
85 SERIAL Serial support is enabled.
86 SH SuperH architecture is enabled.
87 SMP The kernel is an SMP kernel.
88 SPARC Sparc architecture is enabled.
89 SWSUSP Software suspend is enabled.
90 TS Appropriate touchscreen support is enabled.
91 USB USB support is enabled.
92 USBHID USB Human Interface Device support is enabled.
93 V4L Video For Linux support is enabled.
94 VGA The VGA console has been enabled.
95 VT Virtual terminal support is enabled.
96 WDT Watchdog support is enabled.
97 XT IBM PC/XT MFM hard disk support is enabled.
98 X86-32 X86-32, aka i386 architecture is enabled.
99 X86-64 X86-64 architecture is enabled.
100 More X86-64 boot options can be found in
101 Documentation/x86_64/boot-options.txt .
103 In addition, the following text indicates that the option:
105 BUGS= Relates to possible processor bugs on the said processor.
106 KNL Is a kernel start-up parameter.
107 BOOT Is a boot loader parameter.
109 Parameters denoted with BOOT are actually interpreted by the boot
110 loader, and have no meaning to the kernel directly.
111 Do not modify the syntax of boot loader parameters without extreme
112 need or coordination with <Documentation/i386/boot.txt>.
114 There are also arch-specific kernel-parameters not documented here.
115 See for example <Documentation/x86_64/boot-options.txt>.
117 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
118 a trailing = on the name of any parameter states that that parameter will
119 be entered as an environment variable, whereas its absence indicates that
120 it will appear as a kernel argument readable via /proc/cmdline by programs
121 running once the system is up.
123 The number of kernel parameters is not limited, but the length of the
124 complete command line (parameters including spaces etc.) is limited to
125 a fixed number of characters. This limit depends on the architecture
126 and is between 256 and 4096 characters. It is defined in the file
127 ./include/asm/setup.h as COMMAND_LINE_SIZE.
130 acpi= [HW,ACPI,X86-64,i386]
131 Advanced Configuration and Power Interface
132 Format: { force | off | ht | strict | noirq }
133 force -- enable ACPI if default was off
134 off -- disable ACPI if default was on
135 noirq -- do not use ACPI for IRQ routing
136 ht -- run only enough ACPI to enable Hyper Threading
137 strict -- Be less tolerant of platforms that are not
138 strictly ACPI specification compliant.
140 See also Documentation/pm.txt, pci=noacpi
142 acpi_apic_instance= [ACPI, IOAPIC]
143 Format: <int>
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
146 default: 0
148 acpi_sleep= [HW,ACPI] Sleep options
149 Format: { s3_bios, s3_mode }
150 See Documentation/power/video.txt
152 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
153 Format: { level | edge | high | low }
155 acpi_irq_balance [HW,ACPI]
156 ACPI will balance active IRQs
157 default in APIC mode
159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
161 default in PIC mode
163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
164 use by PCI
165 Format: <irq>,<irq>...
167 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
168 Format: <irq>,<irq>...
170 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
172 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
173 Format: To spoof as Windows 98: ="Microsoft Windows"
175 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
176 acpi_osi="string1" # add string1 -- only one string
177 acpi_osi="!string2" # remove built-in string2
178 acpi_osi= # disable all strings
180 acpi_serialize [HW,ACPI] force serialization of AML methods
182 acpi_skip_timer_override [HW,ACPI]
183 Recognize and ignore IRQ0/pin2 Interrupt Override.
184 For broken nForce2 BIOS resulting in XT-PIC timer.
185 acpi_use_timer_override [HW,ACPI}
186 Use timer override. For some broken Nvidia NF5 boards
187 that require a timer override, but don't have
188 HPET
190 acpi.debug_layer= [HW,ACPI]
191 Format: <int>
192 Each bit of the <int> indicates an ACPI debug layer,
193 1: enable, 0: disable. It is useful for boot time
194 debugging. After system has booted up, it can be set
195 via /sys/module/acpi/parameters/debug_layer.
196 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
197 Available bits (add the numbers together) to enable debug output
198 for specific parts of the ACPI subsystem:
199 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
200 0x10 namespace 0x20 parser 0x40 dispatcher
201 0x80 executer 0x100 resources 0x200 acpica debugger
202 0x400 os services 0x800 acpica disassembler.
203 The number can be in decimal or prefixed with 0x in hex.
204 Warning: Many of these options can produce a lot of
205 output and make your system unusable. Be very careful.
207 acpi.debug_level= [HW,ACPI]
208 Format: <int>
209 Each bit of the <int> indicates an ACPI debug level,
210 1: enable, 0: disable. It is useful for boot time
211 debugging. After system has booted up, it can be set
212 via /sys/module/acpi/parameters/debug_level.
213 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
214 Available bits (add the numbers together) to enable different
215 debug output levels of the ACPI subsystem:
216 0x01 error 0x02 warn 0x04 init 0x08 debug object
217 0x10 info 0x20 init names 0x40 parse 0x80 load
218 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
219 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
220 0x10000 resources 0x20000 user requests 0x40000 package.
221 The number can be in decimal or prefixed with 0x in hex.
222 Warning: Many of these options can produce a lot of
223 output and make your system unusable. Be very careful.
225 acpi_pm_good [X86-32,X86-64]
226 Override the pmtimer bug detection: force the kernel
227 to assume that this machine's pmtimer latches its value
228 and always returns good values.
230 agp= [AGP]
231 { off | try_unsupported }
232 off: disable AGP support
233 try_unsupported: try to drive unsupported chipsets
234 (may crash computer or cause data corruption)
236 enable_timer_pin_1 [i386,x86-64]
237 Enable PIN 1 of APIC timer
238 Can be useful to work around chipset bugs
239 (in particular on some ATI chipsets).
240 The kernel tries to set a reasonable default.
242 disable_timer_pin_1 [i386,x86-64]
243 Disable PIN 1 of APIC timer
244 Can be useful to work around chipset bugs.
246 ad1848= [HW,OSS]
247 Format: <io>,<irq>,<dma>,<dma2>,<type>
249 advansys= [HW,SCSI]
250 See header of drivers/scsi/advansys.c.
252 advwdt= [HW,WDT] Advantech WDT
253 Format: <iostart>,<iostop>
255 aedsp16= [HW,OSS] Audio Excel DSP 16
256 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
257 See also header of sound/oss/aedsp16.c.
259 aha152x= [HW,SCSI]
260 See Documentation/scsi/aha152x.txt.
262 aha1542= [HW,SCSI]
263 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
265 aic7xxx= [HW,SCSI]
266 See Documentation/scsi/aic7xxx.txt.
268 aic79xx= [HW,SCSI]
269 See Documentation/scsi/aic79xx.txt.
271 amijoy.map= [HW,JOY] Amiga joystick support
272 Map of devices attached to JOY0DAT and JOY1DAT
273 Format: <a>,<b>
274 See also Documentation/kernel/input/joystick.txt
276 analog.map= [HW,JOY] Analog joystick and gamepad support
277 Specifies type or capabilities of an analog joystick
278 connected to one of 16 gameports
279 Format: <type1>,<type2>,..<type16>
281 apc= [HW,SPARC]
282 Power management functions (SPARCstation-4/5 + deriv.)
283 Format: noidle
284 Disable APC CPU standby support. SPARCstation-Fox does
285 not play well with APC CPU idle - disable it if you have
286 APC and your system crashes randomly.
288 apic= [APIC,i386] Advanced Programmable Interrupt Controller
289 Change the output verbosity whilst booting
290 Format: { quiet (default) | verbose | debug }
291 Change the amount of debugging information output
292 when initialising the APIC and IO-APIC components.
294 apm= [APM] Advanced Power Management
295 See header of arch/i386/kernel/apm.c.
297 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
298 Format: <io>,<irq>,<nodeID>
300 ataflop= [HW,M68k]
302 atarimouse= [HW,MOUSE] Atari Mouse
304 atascsi= [HW,SCSI] Atari SCSI
306 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
307 EzKey and similar keyboards
309 atkbd.reset= [HW] Reset keyboard during initialization
311 atkbd.set= [HW] Select keyboard code set
312 Format: <int> (2 = AT (default), 3 = PS/2)
314 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
315 keyboards
317 atkbd.softraw= [HW] Choose between synthetic and real raw mode
318 Format: <bool> (0 = real, 1 = synthetic (default))
320 atkbd.softrepeat= [HW]
321 Use software keyboard repeat
323 autotest [IA64]
325 baycom_epp= [HW,AX25]
326 Format: <io>,<mode>
328 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
329 Format: <io>,<mode>
330 See header of drivers/net/hamradio/baycom_par.c.
332 baycom_ser_fdx= [HW,AX25]
333 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
334 Format: <io>,<irq>,<mode>[,<baud>]
335 See header of drivers/net/hamradio/baycom_ser_fdx.c.
337 baycom_ser_hdx= [HW,AX25]
338 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
339 Format: <io>,<irq>,<mode>
340 See header of drivers/net/hamradio/baycom_ser_hdx.c.
342 boot_delay= Milliseconds to delay each printk during boot.
343 Values larger than 10 seconds (10000) are changed to
344 no delay (0).
345 Format: integer
347 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
348 bttv.radio= Most important insmod options are available as
349 kernel args too.
350 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
351 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
353 BusLogic= [HW,SCSI]
354 See drivers/scsi/BusLogic.c, comment before function
355 BusLogic_ParseDriverOptions().
357 c101= [NET] Moxa C101 synchronous serial card
359 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
360 Sometimes CPU hardware bugs make them report the cache
361 size incorrectly. The kernel will attempt work arounds
362 to fix known problems, but for some CPUs it is not
363 possible to determine what the correct size should be.
364 This option provides an override for these situations.
366 capability.disable=
367 [SECURITY] Disable capabilities. This would normally
368 be used only if an alternative security model is to be
369 configured. Potentially dangerous and should only be
370 used if you are entirely sure of the consequences.
372 chandev= [HW,NET] Generic channel device initialisation
374 checkreqprot [SELINUX] Set initial checkreqprot flag value.
375 Format: { "0" | "1" }
376 See security/selinux/Kconfig help text.
377 0 -- check protection applied by kernel (includes
378 any implied execute protection).
379 1 -- check protection requested by application.
380 Default value is set via a kernel config option.
381 Value can be changed at runtime via
382 /selinux/checkreqprot.
384 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
385 [Deprecated]
386 Forces specified clocksource (if available) to be used
387 when calculating gettimeofday(). If specified
388 clocksource is not available, it defaults to PIT.
389 Format: { pit | tsc | cyclone | pmtmr }
391 clocksource= [GENERIC_TIME] Override the default clocksource
392 Format: <string>
393 Override the default clocksource and use the clocksource
394 with the name specified.
395 Some clocksource names to choose from, depending on
396 the platform:
397 [all] jiffies (this is the base, fallback clocksource)
398 [ACPI] acpi_pm
399 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
400 pxa_timer,timer3,32k_counter,timer0_1
401 [AVR32] avr32
402 [X86-32] pit,hpet,tsc,vmi-timer;
403 scx200_hrt on Geode; cyclone on IBM x440
404 [MIPS] MIPS
405 [PARISC] cr16
406 [S390] tod
407 [SH] SuperH
408 [SPARC64] tick
409 [X86-64] hpet,tsc
411 code_bytes [IA32] How many bytes of object code to print in an
412 oops report.
413 Range: 0 - 8192
414 Default: 64
416 disable_8254_timer
417 enable_8254_timer
418 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
419 over the 8254 in addition to over the IO-APIC. The
420 kernel tries to set a sensible default.
422 hpet= [X86-32,HPET] option to disable HPET and use PIT.
423 Format: disable
425 com20020= [HW,NET] ARCnet - COM20020 chipset
426 Format:
427 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
429 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
430 Format: <io>[,<irq>]
432 com90xx= [HW,NET]
433 ARCnet - COM90xx chipset (memory-mapped buffers)
434 Format: <io>[,<irq>[,<memstart>]]
436 condev= [HW,S390] console device
437 conmode=
439 console= [KNL] Output console device and options.
441 tty<n> Use the virtual console device <n>.
443 ttyS<n>[,options]
444 ttyUSB0[,options]
445 Use the specified serial port. The options are of
446 the form "bbbbpnf", where "bbbb" is the baud rate,
447 "p" is parity ("n", "o", or "e"), "n" is number of
448 bits, and "f" is flow control ("r" for RTS or
449 omit it). Default is "9600n8".
451 See Documentation/serial-console.txt for more
452 information. See
453 Documentation/networking/netconsole.txt for an
454 alternative.
456 uart[8250],io,<addr>[,options]
457 uart[8250],mmio,<addr>[,options]
458 Start an early, polled-mode console on the 8250/16550
459 UART at the specified I/O port or MMIO address,
460 switching to the matching ttyS device later. The
461 options are the same as for ttyS, above.
463 earlycon= [KNL] Output early console device and options.
464 uart[8250],io,<addr>[,options]
465 uart[8250],mmio,<addr>[,options]
466 Start an early, polled-mode console on the 8250/16550
467 UART at the specified I/O port or MMIO address.
468 The options are the same as for ttyS, above.
470 no_console_suspend
471 [HW] Never suspend the console
472 Disable suspending of consoles during suspend and
473 hibernate operations. Once disabled, debugging
474 messages can reach various consoles while the rest
475 of the system is being put to sleep (ie, while
476 debugging driver suspend/resume hooks). This may
477 not work reliably with all consoles, but is known
478 to work with serial and VGA consoles.
480 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
481 Format:
482 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
484 crashkernel=nn[KMG]@ss[KMG]
485 [KNL] Reserve a chunk of physical memory to
486 hold a kernel to switch to with kexec on panic.
488 crashkernel=range1:size1[,range2:size2,...][@offset]
489 [KNL] Same as above, but depends on the memory
490 in the running system. The syntax of range is
491 start-[end] where start and end are both
492 a memory unit (amount[KMG]). See also
493 Documentation/kdump/kdump.txt for a example.
495 cs4232= [HW,OSS]
496 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
498 cs89x0_dma= [HW,NET]
499 Format: <dma>
501 cs89x0_media= [HW,NET]
502 Format: { rj45 | aui | bnc }
504 dasd= [HW,NET]
505 See header of drivers/s390/block/dasd_devmap.c.
507 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
508 (one device per port)
509 Format: <port#>,<type>
510 See also Documentation/input/joystick-parport.txt
512 debug [KNL] Enable kernel debugging (events log level).
514 debug_locks_verbose=
515 [KNL] verbose self-tests
516 Format=<0|1>
517 Print debugging info while doing the locking API
518 self-tests.
519 We default to 0 (no extra messages), setting it to
520 1 will print _a lot_ more information - normally
521 only useful to kernel developers.
523 decnet= [HW,NET]
524 Format: <area>[,<node>]
525 See also Documentation/networking/decnet.txt.
527 default_blu= [VT]
528 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
529 Change the default blue palette of the console.
530 This is a 16-member array composed of values
531 ranging from 0-255.
533 default_grn= [VT]
534 Format: <green0>,<green1>,<green2>,...,<green15>
535 Change the default green palette of the console.
536 This is a 16-member array composed of values
537 ranging from 0-255.
539 default_red= [VT]
540 Format: <red0>,<red1>,<red2>,...,<red15>
541 Change the default red palette of the console.
542 This is a 16-member array composed of values
543 ranging from 0-255.
545 default_utf8= [VT]
546 Format=<0|1>
547 Set system-wide default UTF-8 mode for all tty's.
548 Default is 0 and by setting to 1, it enables UTF-8
549 mode for all newly opened or allocated terminals.
551 dhash_entries= [KNL]
552 Set number of hash buckets for dentry cache.
554 digi= [HW,SERIAL]
555 IO parameters + enable/disable command.
557 digiepca= [HW,SERIAL]
558 See drivers/char/README.epca and
559 Documentation/digiepca.txt.
561 dmasound= [HW,OSS] Sound subsystem buffers
563 dscc4.setup= [NET]
565 dtc3181e= [HW,SCSI]
567 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
568 earlyprintk=vga
569 earlyprintk=serial[,ttySn[,baudrate]]
571 Append ",keep" to not disable it when the real console
572 takes over.
574 Only vga or serial at a time, not both.
576 Currently only ttyS0 and ttyS1 are supported.
578 Interaction with the standard serial driver is not
579 very good.
581 The VGA output is eventually overwritten by the real
582 console.
584 eata= [HW,SCSI]
586 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
587 Format: <int>
588 0: polling mode
589 non-0: interrupt mode (default)
591 edd= [EDD]
592 Format: {"of[f]" | "sk[ipmbr]"}
593 See comment in arch/i386/boot/edd.S
595 eisa_irq_edge= [PARISC,HW]
596 See header of drivers/parisc/eisa.c.
598 elanfreq= [X86-32]
599 See comment before function elanfreq_setup() in
600 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
602 elevator= [IOSCHED]
603 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
604 See Documentation/block/as-iosched.txt and
605 Documentation/block/deadline-iosched.txt for details.
607 elfcorehdr= [X86-32, X86_64]
608 Specifies physical address of start of kernel core
609 image elf header. Generally kexec loader will
610 pass this option to capture kernel.
611 See Documentation/kdump/kdump.txt for details.
613 enforcing [SELINUX] Set initial enforcing status.
614 Format: {"0" | "1"}
615 See security/selinux/Kconfig help text.
616 0 -- permissive (log only, no denials).
617 1 -- enforcing (deny and log).
618 Default value is 0.
619 Value can be changed at runtime via /selinux/enforce.
621 es1371= [HW,OSS]
622 Format: <spdif>,[<nomix>,[<amplifier>]]
623 See also header of sound/oss/es1371.c.
625 ether= [HW,NET] Ethernet cards parameters
626 This option is obsoleted by the "netdev=" option, which
627 has equivalent usage. See its documentation for details.
629 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
630 Format: <io>[,<irq>]
632 failslab=
633 fail_page_alloc=
634 fail_make_request=[KNL]
635 General fault injection mechanism.
636 Format: <interval>,<probability>,<space>,<times>
637 See also /Documentation/fault-injection/.
639 fd_mcs= [HW,SCSI]
640 See header of drivers/scsi/fd_mcs.c.
642 fdomain= [HW,SCSI]
643 See header of drivers/scsi/fdomain.c.
645 floppy= [HW]
646 See Documentation/floppy.txt.
648 gamecon.map[2|3]=
649 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
650 support via parallel port (up to 5 devices per port)
651 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
652 See also Documentation/input/joystick-parport.txt
654 gamma= [HW,DRM]
656 gdth= [HW,SCSI]
657 See header of drivers/scsi/gdth.c.
659 gpt [EFI] Forces disk with valid GPT signature but
660 invalid Protective MBR to be treated as GPT.
662 gvp11= [HW,SCSI]
664 hashdist= [KNL,NUMA] Large hashes allocated during boot
665 are distributed across NUMA nodes. Defaults on
666 for IA-64, off otherwise.
667 Format: 0 | 1 (for off | on)
669 hcl= [IA-64] SGI's Hardware Graph compatibility layer
671 hd= [EIDE] (E)IDE hard drive subsystem geometry
672 Format: <cyl>,<head>,<sect>
674 hd?= [HW] (E)IDE subsystem
675 hd?lun= See Documentation/ide.txt.
677 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
678 size of <nn>. This works even on boxes that have no
679 highmem otherwise. This also works to reduce highmem
680 size on bigger boxes.
682 highres= [KNL] Enable/disable high resolution timer mode.
683 Valid parameters: "on", "off"
684 Default: "on"
686 hisax= [HW,ISDN]
687 See Documentation/isdn/README.HiSax.
689 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
691 i8042.direct [HW] Put keyboard port into non-translated mode
692 i8042.dumbkbd [HW] Pretend that controller can only read data from
693 keyboard and cannot control its state
694 (Don't attempt to blink the leds)
695 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
696 i8042.nokbd [HW] Don't check/create keyboard port
697 i8042.nomux [HW] Don't check presence of an active multiplexing
698 controller
699 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
700 controllers
701 i8042.panicblink=
702 [HW] Frequency with which keyboard LEDs should blink
703 when kernel panics (default is 0.5 sec)
704 i8042.reset [HW] Reset the controller during init and cleanup
705 i8042.unlock [HW] Unlock (ignore) the keylock
707 i810= [HW,DRM]
709 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
710 indicates that the driver is running on unsupported
711 hardware.
712 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
713 does not match list of supported models.
714 i8k.power_status
715 [HW] Report power status in /proc/i8k
716 (disabled by default)
717 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
718 capability is set.
720 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
721 See Documentation/mca.txt.
723 icn= [HW,ISDN]
724 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
726 ide= [HW] (E)IDE subsystem
727 Format: ide=nodma or ide=doubler or ide=reverse
728 See Documentation/ide.txt.
730 ide?= [HW] (E)IDE subsystem
731 Format: ide?=noprobe or chipset specific parameters.
732 See Documentation/ide.txt.
734 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
735 See Documentation/ide.txt.
737 idle= [X86]
738 Format: idle=poll or idle=mwait
739 Poll forces a polling idle loop that can slightly improves the performance
740 of waking up a idle CPU, but will use a lot of power and make the system
741 run hot. Not recommended.
742 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
743 to not use it because it doesn't save as much power as a normal idle
744 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
745 as idle=poll.
747 ignore_loglevel [KNL]
748 Ignore loglevel setting - this will print /all/
749 kernel messages to the console. Useful for debugging.
751 ihash_entries= [KNL]
752 Set number of hash buckets for inode cache.
754 in2000= [HW,SCSI]
755 See header of drivers/scsi/in2000.c.
757 init= [KNL]
758 Format: <full_path>
759 Run specified binary instead of /sbin/init as init
760 process.
762 initcall_debug [KNL] Trace initcalls as they are executed. Useful
763 for working out where the kernel is dying during
764 startup.
766 initrd= [BOOT] Specify the location of the initial ramdisk
768 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
769 Format: <irq>
771 inttest= [IA64]
773 io7= [HW] IO7 for Marvel based alpha systems
774 See comment before marvel_specify_io7 in
775 arch/alpha/kernel/core_marvel.c.
777 ip= [IP_PNP]
778 See Documentation/nfsroot.txt.
780 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
781 See comment before ip2_setup() in
782 drivers/char/ip2/ip2base.c.
784 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
785 See header of drivers/scsi/ips.c.
787 ports= [IP_VS_FTP] IPVS ftp helper module
788 Default is 21.
789 Up to 8 (IP_VS_APP_MAX_PORTS) ports
790 may be specified.
791 Format: <port>,<port>....
793 irqfixup [HW]
794 When an interrupt is not handled search all handlers
795 for it. Intended to get systems with badly broken
796 firmware running.
798 irqpoll [HW]
799 When an interrupt is not handled search all handlers
800 for it. Also check all handlers each timer
801 interrupt. Intended to get systems with badly broken
802 firmware running.
804 isapnp= [ISAPNP]
805 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
807 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
808 Format:
809 <cpu number>,...,<cpu number>
810 or
811 <cpu number>-<cpu number> (must be a positive range in ascending order)
812 or a mixture
813 <cpu number>,...,<cpu number>-<cpu number>
814 This option can be used to specify one or more CPUs
815 to isolate from the general SMP balancing and scheduling
816 algorithms. The only way to move a process onto or off
817 an "isolated" CPU is via the CPU affinity syscalls.
818 <cpu number> begins at 0 and the maximum value is
819 "number of CPUs in system - 1".
821 This option is the preferred way to isolate CPUs. The
822 alternative -- manually setting the CPU mask of all
823 tasks in the system -- can cause problems and
824 suboptimal load balancer performance.
826 iucv= [HW,NET]
828 js= [HW,JOY] Analog joystick
829 See Documentation/input/joystick.txt.
831 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
832 specifies the amount of memory usable by the kernel
833 for non-movable allocations. The requested amount is
834 spread evenly throughout all nodes in the system. The
835 remaining memory in each node is used for Movable
836 pages. In the event, a node is too small to have both
837 kernelcore and Movable pages, kernelcore pages will
838 take priority and other nodes will have a larger number
839 of kernelcore pages. The Movable zone is used for the
840 allocation of pages that may be reclaimed or moved
841 by the page migration subsystem. This means that
842 HugeTLB pages may not be allocated from this zone.
843 Note that allocations like PTEs-from-HighMem still
844 use the HighMem zone if it exists, and the Normal
845 zone if it does not.
847 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
848 is similar to kernelcore except it specifies the
849 amount of memory used for migratable allocations.
850 If both kernelcore and movablecore is specified,
851 then kernelcore will be at *least* the specified
852 value but may be more. If movablecore on its own
853 is specified, the administrator must be careful
854 that the amount of memory usable for all allocations
855 is not too small.
857 keepinitrd [HW,ARM]
859 kstack=N [X86-32,X86-64] Print N words from the kernel stack
860 in oops dumps.
862 l2cr= [PPC]
864 lapic [X86-32,APIC] Enable the local APIC even if BIOS
865 disabled it.
867 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
868 C2 power state.
870 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
871 when set.
872 Format: <int>
874 load_ramdisk= [RAM] List of ramdisks to load from floppy
875 See Documentation/ramdisk.txt.
877 lockd.nlm_grace_period=P [NFS] Assign grace period.
878 Format: <integer>
880 lockd.nlm_tcpport=N [NFS] Assign TCP port.
881 Format: <integer>
883 lockd.nlm_timeout=T [NFS] Assign timeout value.
884 Format: <integer>
886 lockd.nlm_udpport=M [NFS] Assign UDP port.
887 Format: <integer>
889 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
890 Format: <irq>
892 loglevel= All Kernel Messages with a loglevel smaller than the
893 console loglevel will be printed to the console. It can
894 also be changed with klogd or other programs. The
895 loglevels are defined as follows:
897 0 (KERN_EMERG) system is unusable
898 1 (KERN_ALERT) action must be taken immediately
899 2 (KERN_CRIT) critical conditions
900 3 (KERN_ERR) error conditions
901 4 (KERN_WARNING) warning conditions
902 5 (KERN_NOTICE) normal but significant condition
903 6 (KERN_INFO) informational
904 7 (KERN_DEBUG) debug-level messages
906 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
907 Format: { n | nk | nM }
908 n must be a power of two. The default size
909 is set in the kernel config file.
911 logo.nologo [FB] Disables display of the built-in Linux logo.
912 This may be used to provide more screen space for
913 kernel log messages and is useful when debugging
914 kernel boot problems.
916 lp=0 [LP] Specify parallel ports to use, e.g,
917 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
918 lp=reset first parallel port). 'lp=0' disables the
919 lp=auto printer driver. 'lp=reset' (which can be
920 specified in addition to the ports) causes
921 attached printers to be reset. Using
922 lp=port1,port2,... specifies the parallel ports
923 to associate lp devices with, starting with
924 lp0. A port specification may be 'none' to skip
925 that lp device, or a parport name such as
926 'parport0'. Specifying 'lp=auto' instead of a
927 port specification list means that device IDs
928 from each port should be examined, to see if
929 an IEEE 1284-compliant printer is attached; if
930 so, the driver will manage that printer.
931 See also header of drivers/char/lp.c.
933 lpj=n [KNL]
934 Sets loops_per_jiffy to given constant, thus avoiding
935 time-consuming boot-time autodetection (up to 250 ms per
936 CPU). 0 enables autodetection (default). To determine
937 the correct value for your kernel, boot with normal
938 autodetection and see what value is printed. Note that
939 on SMP systems the preset will be applied to all CPUs,
940 which is likely to cause problems if your CPUs need
941 significantly divergent settings. An incorrect value
942 will cause delays in the kernel to be wrong, leading to
943 unpredictable I/O errors and other breakage. Although
944 unlikely, in the extreme case this might damage your
945 hardware.
947 ltpc= [NET]
948 Format: <io>,<irq>,<dma>
950 mac5380= [HW,SCSI] Format:
951 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
953 mac53c9x= [HW,SCSI] Format:
954 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
956 machvec= [IA64] Force the use of a particular machine-vector
957 (machvec) in a generic kernel.
958 Example: machvec=hpzx1_swiotlb
960 max_loop= [LOOP] Maximum number of loopback devices that can
961 be mounted
962 Format: <1-256>
964 maxcpus= [SMP] Maximum number of processors that an SMP kernel
965 should make use of. maxcpus=n : n >= 0 limits the
966 kernel to using 'n' processors. n=0 is a special case,
967 it is equivalent to "nosmp", which also disables
968 the IO APIC.
970 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
971 equal to this physical address is ignored.
973 max_luns= [SCSI] Maximum number of LUNs to probe.
974 Should be between 1 and 2^32-1.
976 max_report_luns=
977 [SCSI] Maximum number of LUNs received.
978 Should be between 1 and 16384.
980 mca-pentium [BUGS=X86-32]
982 mcatest= [IA-64]
984 mce [X86-32] Machine Check Exception
986 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
988 md= [HW] RAID subsystems devices and level
989 See Documentation/md.txt.
991 mdacon= [MDA]
992 Format: <first>,<last>
993 Specifies range of consoles to be captured by the MDA.
995 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
996 Amount of memory to be used when the kernel is not able
997 to see the whole system memory or for test.
998 [X86-32] Use together with memmap= to avoid physical
999 address space collisions. Without memmap= PCI devices
1000 could be placed at addresses belonging to unused RAM.
1002 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1003 memory.
1005 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1006 E820 memory map, as specified by the user.
1007 Such memmap=exactmap lines can be constructed based on
1008 BIOS output or other requirements. See the memmap=nn@ss
1009 option description.
1011 memmap=nn[KMG]@ss[KMG]
1012 [KNL] Force usage of a specific region of memory
1013 Region of memory to be used, from ss to ss+nn.
1015 memmap=nn[KMG]#ss[KMG]
1016 [KNL,ACPI] Mark specific memory as ACPI data.
1017 Region of memory to be used, from ss to ss+nn.
1019 memmap=nn[KMG]$ss[KMG]
1020 [KNL,ACPI] Mark specific memory as reserved.
1021 Region of memory to be used, from ss to ss+nn.
1023 meye.*= [HW] Set MotionEye Camera parameters
1024 See Documentation/video4linux/meye.txt.
1026 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1027 Multi-Function General Purpose Timers on AMD Geode
1028 platforms.
1030 mga= [HW,DRM]
1032 mousedev.tap_time=
1033 [MOUSE] Maximum time between finger touching and
1034 leaving touchpad surface for touch to be considered
1035 a tap and be reported as a left button click (for
1036 touchpads working in absolute mode only).
1037 Format: <msecs>
1038 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1039 reporting absolute coordinates, such as tablets
1040 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1041 reporting absolute coordinates, such as tablets
1043 mpu401= [HW,OSS]
1044 Format: <io>,<irq>
1046 MTD_Partition= [MTD]
1047 Format: <name>,<region-number>,<size>,<offset>
1049 MTD_Region= [MTD] Format:
1050 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1052 mtdparts= [MTD]
1053 See drivers/mtd/cmdlinepart.c.
1055 mtouchusb.raw_coordinates=
1056 [HW] Make the MicroTouch USB driver use raw coordinates
1057 ('y', default) or cooked coordinates ('n')
1059 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1061 NCR_D700= [HW,SCSI]
1062 See header of drivers/scsi/NCR_D700.c.
1064 ncr5380= [HW,SCSI]
1066 ncr53c400= [HW,SCSI]
1068 ncr53c400a= [HW,SCSI]
1070 ncr53c406a= [HW,SCSI]
1072 ncr53c8xx= [HW,SCSI]
1074 netdev= [NET] Network devices parameters
1075 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1076 Note that mem_start is often overloaded to mean
1077 something different and driver-specific.
1078 This usage is only documented in each driver source
1079 file if at all.
1081 nfsaddrs= [NFS]
1082 See Documentation/nfsroot.txt.
1084 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1085 See Documentation/nfsroot.txt.
1087 nfs.callback_tcpport=
1088 [NFS] set the TCP port on which the NFSv4 callback
1089 channel should listen.
1091 nfs.idmap_cache_timeout=
1092 [NFS] set the maximum lifetime for idmapper cache
1093 entries.
1095 nfs.enable_ino64=
1096 [NFS] enable 64-bit inode numbers.
1097 If zero, the NFS client will fake up a 32-bit inode
1098 number for the readdir() and stat() syscalls instead
1099 of returning the full 64-bit number.
1100 The default is to return 64-bit inode numbers.
1102 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1104 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1105 emulation library even if a 387 maths coprocessor
1106 is present.
1108 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1109 caches in the slab allocator. Saves per-node memory,
1110 but will impact performance.
1112 noalign [KNL,ARM]
1114 noapic [SMP,APIC] Tells the kernel to not make use of any
1115 IOAPICs that may be present in the system.
1117 nobats [PPC] Do not use BATs for mapping kernel lowmem
1118 on "Classic" PPC cores.
1120 nocache [ARM]
1122 nodelayacct [KNL] Disable per-task delay accounting
1124 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1126 noexec [IA-64]
1128 noexec [X86-32,X86-64]
1129 noexec=on: enable non-executable mappings (default)
1130 noexec=off: disable nn-executable mappings
1132 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1133 register save and restore. The kernel will only save
1134 legacy floating-point registers on task switch.
1136 nohlt [BUGS=ARM]
1138 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1139 instruction doesn't work correctly and not to
1140 use it.
1142 nohalt [IA-64] Tells the kernel not to use the power saving
1143 function PAL_HALT_LIGHT when idle. This increases
1144 power-consumption. On the positive side, it reduces
1145 interrupt wake-up latency, which may improve performance
1146 in certain environments such as networked servers or
1147 real-time systems.
1149 nohz= [KNL] Boottime enable/disable dynamic ticks
1150 Valid arguments: on, off
1151 Default: on
1153 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1155 noirqdebug [X86-32] Disables the code which attempts to detect and
1156 disable unhandled interrupt sources.
1158 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1159 broken timer IRQ sources.
1161 noisapnp [ISAPNP] Disables ISA PnP code.
1163 noinitrd [RAM] Tells the kernel not to load any configured
1164 initial RAM disk.
1166 nointroute [IA-64]
1168 nojitter [IA64] Disables jitter checking for ITC timers.
1170 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1172 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1174 noltlbs [PPC] Do not use large page/tlb entries for kernel
1175 lowmem mapping on PPC40x.
1177 nomca [IA-64] Disable machine check abort handling
1179 nomce [X86-32] Machine Check Exception
1181 nomfgpt [X86-32] Disable Multi-Function General Purpose
1182 Timer usage (for AMD Geode machines).
1184 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1186 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1187 with UP alternatives
1189 noresidual [PPC] Don't use residual data on PReP machines.
1191 noresume [SWSUSP] Disables resume and restores original swap
1192 space.
1194 no-scroll [VGA] Disables scrollback.
1195 This is required for the Braillex ib80-piezo Braille
1196 reader made by F.H. Papenmeier (Germany).
1198 nosbagart [IA-64]
1200 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1202 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1203 and disable the IO APIC. legacy for "maxcpus=0".
1205 nosoftlockup [KNL] Disable the soft-lockup detector.
1207 nosync [HW,M68K] Disables sync negotiation for all devices.
1209 notsc [BUGS=X86-32] Disable Time Stamp Counter
1211 nousb [USB] Disable the USB subsystem
1213 nowb [ARM]
1215 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1216 one of ['zone', 'node', 'default'] can be specified
1217 This can be set from sysctl after boot.
1218 See Documentation/sysctl/vm.txt for details.
1220 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1222 opl3= [HW,OSS]
1223 Format: <io>
1225 oprofile.timer= [HW]
1226 Use timer interrupt instead of performance counters
1228 osst= [HW,SCSI] SCSI Tape Driver
1229 Format: <buffer_size>,<write_threshold>
1230 See also Documentation/scsi/st.txt.
1232 panic= [KNL] Kernel behaviour on panic
1233 Format: <timeout>
1235 parkbd.port= [HW] Parallel port number the keyboard adapter is
1236 connected to, default is 0.
1237 Format: <parport#>
1238 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1239 0 for XT, 1 for AT (default is AT).
1240 Format: <mode>
1242 parport= [HW,PPT] Specify parallel ports. 0 disables.
1243 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1244 Use 'auto' to force the driver to use any
1245 IRQ/DMA settings detected (the default is to
1246 ignore detected IRQ/DMA settings because of
1247 possible conflicts). You can specify the base
1248 address, IRQ, and DMA settings; IRQ and DMA
1249 should be numbers, or 'auto' (for using detected
1250 settings on that particular port), or 'nofifo'
1251 (to avoid using a FIFO even if it is detected).
1252 Parallel ports are assigned in the order they
1253 are specified on the command line, starting
1254 with parport0.
1256 parport_init_mode= [HW,PPT]
1257 Configure VIA parallel port to operate in
1258 a specific mode. This is necessary on Pegasos
1259 computer where firmware has no options for setting
1260 up parallel port mode and sets it to spp.
1261 Currently this function knows 686a and 8231 chips.
1262 Format: [spp|ps2|epp|ecp|ecpepp]
1264 pas2= [HW,OSS] Format:
1265 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1267 pas16= [HW,SCSI]
1268 See header of drivers/scsi/pas16.c.
1270 pause_on_oops=
1271 Halt all CPUs after the first oops has been printed for
1272 the specified number of seconds. This is to be used if
1273 your oopses keep scrolling off the screen.
1275 pcbit= [HW,ISDN]
1277 pcd. [PARIDE]
1278 See header of drivers/block/paride/pcd.c.
1279 See also Documentation/paride.txt.
1281 pci=option[,option...] [PCI] various PCI subsystem options:
1282 off [X86-32] don't probe for the PCI bus
1283 bios [X86-32] force use of PCI BIOS, don't access
1284 the hardware directly. Use this if your machine
1285 has a non-standard PCI host bridge.
1286 nobios [X86-32] disallow use of PCI BIOS, only direct
1287 hardware access methods are allowed. Use this
1288 if you experience crashes upon bootup and you
1289 suspect they are caused by the BIOS.
1290 conf1 [X86-32] Force use of PCI Configuration
1291 Mechanism 1.
1292 conf2 [X86-32] Force use of PCI Configuration
1293 Mechanism 2.
1294 noaer [PCIE] If the PCIEAER kernel config parameter is
1295 enabled, this kernel boot option can be used to
1296 disable the use of PCIE advanced error reporting.
1297 nodomains [PCI] Disable support for multiple PCI
1298 root domains (aka PCI segments, in ACPI-speak).
1299 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1300 Configuration
1301 nomsi [MSI] If the PCI_MSI kernel config parameter is
1302 enabled, this kernel boot option can be used to
1303 disable the use of MSI interrupts system-wide.
1304 nosort [X86-32] Don't sort PCI devices according to
1305 order given by the PCI BIOS. This sorting is
1306 done to get a device order compatible with
1307 older kernels.
1308 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1309 routing table. These calls are known to be buggy
1310 on several machines and they hang the machine
1311 when used, but on other computers it's the only
1312 way to get the interrupt routing table. Try
1313 this option if the kernel is unable to allocate
1314 IRQs or discover secondary PCI buses on your
1315 motherboard.
1316 rom [X86-32] Assign address space to expansion ROMs.
1317 Use with caution as certain devices share
1318 address decoders between ROMs and other
1319 resources.
1320 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1321 assigned automatically to PCI devices. You can
1322 make the kernel exclude IRQs of your ISA cards
1323 this way.
1324 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1325 of the PIRQ table (normally generated
1326 by the BIOS) if it is outside the
1327 F0000h-100000h range.
1328 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1329 useful if the kernel is unable to find your
1330 secondary buses and you want to tell it
1331 explicitly which ones they are.
1332 assign-busses [X86-32] Always assign all PCI bus
1333 numbers ourselves, overriding
1334 whatever the firmware may have done.
1335 usepirqmask [X86-32] Honor the possible IRQ mask stored
1336 in the BIOS $PIR table. This is needed on
1337 some systems with broken BIOSes, notably
1338 some HP Pavilion N5400 and Omnibook XE3
1339 notebooks. This will have no effect if ACPI
1340 IRQ routing is enabled.
1341 noacpi [X86-32] Do not use ACPI for IRQ routing
1342 or for PCI scanning.
1343 use_crs [X86-32] Use _CRS for PCI resource
1344 allocation.
1345 routeirq Do IRQ routing for all PCI devices.
1346 This is normally done in pci_enable_device(),
1347 so this option is a temporary workaround
1348 for broken drivers that don't call it.
1349 firmware [ARM] Do not re-enumerate the bus but instead
1350 just use the configuration from the
1351 bootloader. This is currently used on
1352 IXP2000 systems where the bus has to be
1353 configured a certain way for adjunct CPUs.
1354 noearly [X86] Don't do any early type 1 scanning.
1355 This might help on some broken boards which
1356 machine check when some devices' config space
1357 is read. But various workarounds are disabled
1358 and some IOMMU drivers will not work.
1359 bfsort Sort PCI devices into breadth-first order.
1360 This sorting is done to get a device
1361 order compatible with older (<= 2.4) kernels.
1362 nobfsort Don't sort PCI devices into breadth-first order.
1363 cbiosize=nn[KMG] The fixed amount of bus space which is
1364 reserved for the CardBus bridge's IO window.
1365 The default value is 256 bytes.
1366 cbmemsize=nn[KMG] The fixed amount of bus space which is
1367 reserved for the CardBus bridge's memory
1368 window. The default value is 64 megabytes.
1370 pcmv= [HW,PCMCIA] BadgePAD 4
1372 pd. [PARIDE]
1373 See Documentation/paride.txt.
1375 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1376 boot time.
1377 Format: { 0 | 1 }
1378 See arch/parisc/kernel/pdc_chassis.c
1380 pf. [PARIDE]
1381 See Documentation/paride.txt.
1383 pg. [PARIDE]
1384 See Documentation/paride.txt.
1386 pirq= [SMP,APIC] Manual mp-table setup
1387 See Documentation/i386/IO-APIC.txt.
1389 plip= [PPT,NET] Parallel port network link
1390 Format: { parport<nr> | timid | 0 }
1391 See also Documentation/parport.txt.
1393 pnpacpi= [ACPI]
1394 { off }
1396 pnpbios= [ISAPNP]
1397 { on | off | curr | res | no-curr | no-res }
1399 pnp_reserve_irq=
1400 [ISAPNP] Exclude IRQs for the autoconfiguration
1402 pnp_reserve_dma=
1403 [ISAPNP] Exclude DMAs for the autoconfiguration
1405 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1406 Ranges are in pairs (I/O port base and size).
1408 pnp_reserve_mem=
1409 [ISAPNP] Exclude memory regions for the
1410 autoconfiguration.
1411 Ranges are in pairs (memory base and size).
1413 print-fatal-signals=
1414 [KNL] debug: print fatal signals
1415 print-fatal-signals=1: print segfault info to
1416 the kernel console.
1417 default: off.
1419 printk.time= Show timing data prefixed to each printk message line
1420 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1422 profile= [KNL] Enable kernel profiling via /proc/profile
1423 Format: [schedule,]<number>
1424 Param: "schedule" - profile schedule points.
1425 Param: <number> - step/bucket size as a power of 2 for
1426 statistical time based profiling.
1427 Param: "sleep" - profile D-state sleeping (millisecs)
1429 processor.max_cstate= [HW,ACPI]
1430 Limit processor to maximum C-state
1431 max_cstate=9 overrides any DMI blacklist limit.
1433 processor.nocst [HW,ACPI]
1434 Ignore the _CST method to determine C-states,
1435 instead using the legacy FADT method
1437 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1438 before loading.
1439 See Documentation/ramdisk.txt.
1441 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1442 probe for; one of (bare|imps|exps|lifebook|any).
1443 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1444 per second.
1445 psmouse.resetafter= [HW,MOUSE]
1446 Try to reset the device after so many bad packets
1447 (0 = never).
1448 psmouse.resolution=
1449 [HW,MOUSE] Set desired mouse resolution, in dpi.
1450 psmouse.smartscroll=
1451 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1452 0 = disabled, 1 = enabled (default).
1454 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1455 Format:
1456 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1458 pt. [PARIDE]
1459 See Documentation/paride.txt.
1461 pty.legacy_count=
1462 [KNL] Number of legacy pty's. Overwrites compiled-in
1463 default number.
1465 quiet [KNL] Disable most log messages
1467 r128= [HW,DRM]
1469 raid= [HW,RAID]
1470 See Documentation/md.txt.
1472 ramdisk_blocksize= [RAM]
1473 See Documentation/ramdisk.txt.
1475 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1476 See Documentation/ramdisk.txt.
1478 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1479 RCU callbacks to process in one batch.
1481 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1482 RCU callbacks over which batch limiting is disabled.
1484 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1485 RCU callbacks below which batch limiting is re-enabled.
1487 rdinit= [KNL]
1488 Format: <full_path>
1489 Run specified binary instead of /init from the ramdisk,
1490 used for early userspace startup. See initrd.
1492 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1493 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1494 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1496 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1498 reservetop= [X86-32]
1499 Format: nn[KMG]
1500 Reserves a hole at the top of the kernel virtual
1501 address space.
1503 reset_devices [KNL] Force drivers to reset the underlying device
1504 during initialization.
1506 resume= [SWSUSP]
1507 Specify the partition device for software suspend
1509 resume_offset= [SWSUSP]
1510 Specify the offset from the beginning of the partition
1511 given by "resume=" at which the swap header is located,
1512 in <PAGE_SIZE> units (needed only for swap files).
1513 See Documentation/power/swsusp-and-swap-files.txt
1515 retain_initrd [RAM] Keep initrd memory after extraction
1517 rhash_entries= [KNL,NET]
1518 Set number of hash buckets for route cache
1520 riscom8= [HW,SERIAL]
1521 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1523 ro [KNL] Mount root device read-only on boot
1525 root= [KNL] Root filesystem
1527 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1528 mount the root filesystem
1530 rootflags= [KNL] Set root filesystem mount option string
1532 rootfstype= [KNL] Set root filesystem type
1534 rootwait [KNL] Wait (indefinitely) for root device to show up.
1535 Useful for devices that are detected asynchronously
1536 (e.g. USB and MMC devices).
1538 root_plug.vendor_id=
1539 [ROOTPLUG] Override the default vendor ID
1541 root_plug.product_id=
1542 [ROOTPLUG] Override the default product ID
1544 root_plug.debug=
1545 [ROOTPLUG] Enable debugging output
1547 rw [KNL] Mount root device read-write on boot
1549 S [KNL] Run init in single mode
1551 sa1100ir [NET]
1552 See drivers/net/irda/sa1100_ir.c.
1554 sbni= [NET] Granch SBNI12 leased line adapter
1556 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1557 Format: <io>[,<timeout>[,<isapnp>]]
1559 scsi_debug_*= [SCSI]
1560 See drivers/scsi/scsi_debug.c.
1562 scsi_default_dev_flags=
1563 [SCSI] SCSI default device flags
1564 Format: <integer>
1566 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1567 Format: <vendor>:<model>:<flags>
1568 (flags are integer value)
1570 scsi_logging= [SCSI]
1572 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1573 discovered. async scans them in kernel threads,
1574 allowing boot to proceed. none ignores them, expecting
1575 user space to do the scan.
1577 selinux [SELINUX] Disable or enable SELinux at boot time.
1578 Format: { "0" | "1" }
1579 See security/selinux/Kconfig help text.
1580 0 -- disable.
1581 1 -- enable.
1582 Default value is set via kernel config option.
1583 If enabled at boot time, /selinux/disable can be used
1584 later to disable prior to initial policy load.
1586 selinux_compat_net =
1587 [SELINUX] Set initial selinux_compat_net flag value.
1588 Format: { "0" | "1" }
1589 0 -- use new secmark-based packet controls
1590 1 -- use legacy packet controls
1591 Default value is 0 (preferred).
1592 Value can be changed at runtime via
1593 /selinux/compat_net.
1595 serialnumber [BUGS=X86-32]
1597 shapers= [NET]
1598 Maximal number of shapers.
1600 sim710= [SCSI,HW]
1601 See header of drivers/scsi/sim710.c.
1603 simeth= [IA-64]
1604 simscsi=
1606 slram= [HW,MTD]
1608 slub_debug[=options[,slabs]] [MM, SLUB]
1609 Enabling slub_debug allows one to determine the
1610 culprit if slab objects become corrupted. Enabling
1611 slub_debug can create guard zones around objects and
1612 may poison objects when not in use. Also tracks the
1613 last alloc / free. For more information see
1614 Documentation/vm/slub.txt.
1616 slub_max_order= [MM, SLUB]
1617 Determines the maximum allowed order for slabs.
1618 A high setting may cause OOMs due to memory
1619 fragmentation. For more information see
1620 Documentation/vm/slub.txt.
1622 slub_min_objects= [MM, SLUB]
1623 The minimum number of objects per slab. SLUB will
1624 increase the slab order up to slub_max_order to
1625 generate a sufficiently large slab able to contain
1626 the number of objects indicated. The higher the number
1627 of objects the smaller the overhead of tracking slabs
1628 and the less frequently locks need to be acquired.
1629 For more information see Documentation/vm/slub.txt.
1631 slub_min_order= [MM, SLUB]
1632 Determines the mininum page order for slabs. Must be
1633 lower than slub_max_order.
1634 For more information see Documentation/vm/slub.txt.
1636 slub_nomerge [MM, SLUB]
1637 Disable merging of slabs with similar size. May be
1638 necessary if there is some reason to distinguish
1639 allocs to different slabs. Debug options disable
1640 merging on their own.
1641 For more information see Documentation/vm/slub.txt.
1643 smart2= [HW]
1644 Format: <io1>[,<io2>[,...,<io8>]]
1646 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1647 attempt to substitute SMP alternatives once at boot.
1649 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1650 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1651 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1652 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1653 smsc-ircc2.ircc_irq= [HW] IRQ line
1654 smsc-ircc2.ircc_dma= [HW] DMA channel
1655 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1656 0: Toshiba Satellite 1800 (GP data pin select)
1657 1: Fast pin select (default)
1658 2: ATC IRMode
1660 snd-ad1816a= [HW,ALSA]
1662 snd-ad1848= [HW,ALSA]
1664 snd-ali5451= [HW,ALSA]
1666 snd-als100= [HW,ALSA]
1668 snd-als4000= [HW,ALSA]
1670 snd-azt2320= [HW,ALSA]
1672 snd-cmi8330= [HW,ALSA]
1674 snd-cmipci= [HW,ALSA]
1676 snd-cs4231= [HW,ALSA]
1678 snd-cs4232= [HW,ALSA]
1680 snd-cs4236= [HW,ALSA]
1682 snd-cs4281= [HW,ALSA]
1684 snd-cs46xx= [HW,ALSA]
1686 snd-dt019x= [HW,ALSA]
1688 snd-dummy= [HW,ALSA]
1690 snd-emu10k1= [HW,ALSA]
1692 snd-ens1370= [HW,ALSA]
1694 snd-ens1371= [HW,ALSA]
1696 snd-es968= [HW,ALSA]
1698 snd-es1688= [HW,ALSA]
1700 snd-es18xx= [HW,ALSA]
1702 snd-es1938= [HW,ALSA]
1704 snd-es1968= [HW,ALSA]
1706 snd-fm801= [HW,ALSA]
1708 snd-gusclassic= [HW,ALSA]
1710 snd-gusextreme= [HW,ALSA]
1712 snd-gusmax= [HW,ALSA]
1714 snd-hdsp= [HW,ALSA]
1716 snd-ice1712= [HW,ALSA]
1718 snd-intel8x0= [HW,ALSA]
1720 snd-interwave= [HW,ALSA]
1722 snd-interwave-stb=
1723 [HW,ALSA]
1725 snd-korg1212= [HW,ALSA]
1727 snd-maestro3= [HW,ALSA]
1729 snd-mpu401= [HW,ALSA]
1731 snd-mtpav= [HW,ALSA]
1733 snd-nm256= [HW,ALSA]
1735 snd-opl3sa2= [HW,ALSA]
1737 snd-opti92x-ad1848=
1738 [HW,ALSA]
1740 snd-opti92x-cs4231=
1741 [HW,ALSA]
1743 snd-opti93x= [HW,ALSA]
1745 snd-pmac= [HW,ALSA]
1747 snd-rme32= [HW,ALSA]
1749 snd-rme96= [HW,ALSA]
1751 snd-rme9652= [HW,ALSA]
1753 snd-sb8= [HW,ALSA]
1755 snd-sb16= [HW,ALSA]
1757 snd-sbawe= [HW,ALSA]
1759 snd-serial= [HW,ALSA]
1761 snd-sgalaxy= [HW,ALSA]
1763 snd-sonicvibes= [HW,ALSA]
1765 snd-sun-amd7930=
1766 [HW,ALSA]
1768 snd-sun-cs4231= [HW,ALSA]
1770 snd-trident= [HW,ALSA]
1772 snd-usb-audio= [HW,ALSA,USB]
1774 snd-via82xx= [HW,ALSA]
1776 snd-virmidi= [HW,ALSA]
1778 snd-wavefront= [HW,ALSA]
1780 snd-ymfpci= [HW,ALSA]
1782 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1783 See Documentation/sonypi.txt
1785 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1786 See Documentation/specialix.txt.
1788 spia_io_base= [HW,MTD]
1789 spia_fio_base=
1790 spia_pedr=
1791 spia_peddr=
1793 sscape= [HW,OSS]
1794 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1796 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1797 See Documentation/scsi/st.txt.
1799 st0x= [HW,SCSI]
1800 See header of drivers/scsi/seagate.c.
1802 sti= [PARISC,HW]
1803 Format: <num>
1804 Set the STI (builtin display/keyboard on the HP-PARISC
1805 machines) console (graphic card) which should be used
1806 as the initial boot-console.
1807 See also comment in drivers/video/console/sticore.c.
1809 sti_font= [HW]
1810 See comment in drivers/video/console/sticore.c.
1812 stifb= [HW]
1813 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1815 sunrpc.pool_mode=
1816 [NFS]
1817 Control how the NFS server code allocates CPUs to
1818 service thread pools. Depending on how many NICs
1819 you have and where their interrupts are bound, this
1820 option will affect which CPUs will do NFS serving.
1821 Note: this parameter cannot be changed while the
1822 NFS server is running.
1824 auto the server chooses an appropriate mode
1825 automatically using heuristics
1826 global a single global pool contains all CPUs
1827 percpu one pool for each CPU
1828 pernode one pool for each NUMA node (equivalent
1829 to global on non-NUMA machines)
1831 swiotlb= [IA-64] Number of I/O TLB slabs
1833 switches= [HW,M68k]
1835 sym53c416= [HW,SCSI]
1836 See header of drivers/scsi/sym53c416.c.
1838 sysrq_always_enabled
1839 [KNL]
1840 Ignore sysrq setting - this boot parameter will
1841 neutralize any effect of /proc/sys/kernel/sysrq.
1842 Useful for debugging.
1844 t128= [HW,SCSI]
1845 See header of drivers/scsi/t128.c.
1847 tdfx= [HW,DRM]
1849 thash_entries= [KNL,NET]
1850 Set number of hash buckets for TCP connection
1852 thermal.act= [HW,ACPI]
1853 -1: disable all active trip points in all thermal zones
1854 <degrees C>: override all lowest active trip points
1856 thermal.crt= [HW,ACPI]
1857 -1: disable all critical trip points in all thermal zones
1858 <degrees C>: lower all critical trip points
1860 thermal.nocrt= [HW,ACPI]
1861 Set to disable actions on ACPI thermal zone
1862 critical and hot trip points.
1864 thermal.off= [HW,ACPI]
1865 1: disable ACPI thermal control
1867 thermal.psv= [HW,ACPI]
1868 -1: disable all passive trip points
1869 <degrees C>: override all passive trip points to this value
1871 thermal.tzp= [HW,ACPI]
1872 Specify global default ACPI thermal zone polling rate
1873 <deci-seconds>: poll all this frequency
1874 0: no polling (default)
1876 time Show timing data prefixed to each printk message line
1877 [deprecated, see 'printk.time']
1879 tipar.timeout= [HW,PPT]
1880 Set communications timeout in tenths of a second
1881 (default 15).
1883 tipar.delay= [HW,PPT]
1884 Set inter-bit delay in microseconds (default 10).
1886 tmc8xx= [HW,SCSI]
1887 See header of drivers/scsi/seagate.c.
1889 tmscsim= [HW,SCSI]
1890 See comment before function dc390_setup() in
1891 drivers/scsi/tmscsim.c.
1893 tp720= [HW,PS2]
1895 trix= [HW,OSS] MediaTrix AudioTrix Pro
1896 Format:
1897 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1899 turbografx.map[2|3]= [HW,JOY]
1900 TurboGraFX parallel port interface
1901 Format:
1902 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1903 See also Documentation/input/joystick-parport.txt
1905 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1906 See header of drivers/scsi/u14-34f.c.
1908 uart401= [HW,OSS]
1909 Format: <io>,<irq>
1911 uart6850= [HW,OSS]
1912 Format: <io>,<irq>
1914 uhci-hcd.ignore_oc=
1915 [USB] Ignore overcurrent events (default N).
1916 Some badly-designed motherboards generate lots of
1917 bogus events, for ports that aren't wired to
1918 anything. Set this parameter to avoid log spamming.
1919 Note that genuine overcurrent events won't be
1920 reported either.
1922 usbcore.autosuspend=
1923 [USB] The autosuspend time delay (in seconds) used
1924 for newly-detected USB devices (default 2). This
1925 is the time required before an idle device will be
1926 autosuspended. Devices for which the delay is set
1927 to a negative value won't be autosuspended at all.
1929 usbhid.mousepoll=
1930 [USBHID] The interval which mice are to be polled at.
1932 vdso= [X86-32,SH,x86-64]
1933 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1934 vdso=1: enable VDSO (default)
1935 vdso=0: disable VDSO mapping
1937 vector= [IA-64,SMP]
1938 vector=percpu: enable percpu vector domain
1940 video= [FB] Frame buffer configuration
1941 See Documentation/fb/modedb.txt.
1943 vga= [BOOT,X86-32] Select a particular video mode
1944 See Documentation/i386/boot.txt and
1945 Documentation/svga.txt.
1946 Use vga=ask for menu.
1947 This is actually a boot loader parameter; the value is
1948 passed to the kernel using a special protocol.
1950 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1951 size of <nn>. This can be used to increase the
1952 minimum size (128MB on x86). It can also be used to
1953 decrease the size and leave more room for directly
1954 mapped kernel RAM.
1956 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1957 Format: <command>
1959 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1960 Format: <command>
1962 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1963 Format: <command>
1965 waveartist= [HW,OSS]
1966 Format: <io>,<irq>,<dma>,<dma2>
1968 wd33c93= [HW,SCSI]
1969 See header of drivers/scsi/wd33c93.c.
1971 wd7000= [HW,SCSI]
1972 See header of drivers/scsi/wd7000.c.
1974 wdt= [WDT] Watchdog
1975 See Documentation/watchdog/wdt.txt.
1977 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1978 xd_geo= See header of drivers/block/xd.c.
1980 xirc2ps_cs= [NET,PCMCIA]
1981 Format:
1982 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1984 norandmaps Don't use address space randomization
1985 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1987 ______________________________________________________________________
1989 TODO:
1991 Add documentation for ALSA options.
1992 Add more DRM drivers.