kernel-parameters.txt 58 KB

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  1. Kernel Parameters
  2. ~~~~~~~~~~~~~~~~~
  3. The following is a consolidated list of the kernel parameters as implemented
  4. (mostly) by the __setup() macro and sorted into English Dictionary order
  5. (defined as ignoring all punctuation and sorting digits before letters in a
  6. case insensitive manner), and with descriptions where known.
  7. Module parameters for loadable modules are specified only as the
  8. parameter name with optional '=' and value as appropriate, such as:
  9. modprobe usbcore blinkenlights=1
  10. Module parameters for modules that are built into the kernel image
  11. are specified on the kernel command line with the module name plus
  12. '.' plus parameter name, with '=' and value if appropriate, such as:
  13. usbcore.blinkenlights=1
  14. This document may not be entirely up to date and comprehensive. The command
  15. "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
  16. module. Loadable modules, after being loaded into the running kernel, also
  17. reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
  18. parameters may be changed at runtime by the command
  19. "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
  20. The parameters listed below are only valid if certain kernel build options were
  21. enabled and if respective hardware is present. The text in square brackets at
  22. the beginning of each description states the restrictions within which a
  23. parameter is applicable:
  24. ACPI ACPI support is enabled.
  25. ALSA ALSA sound support is enabled.
  26. APIC APIC support is enabled.
  27. APM Advanced Power Management support is enabled.
  28. AX25 Appropriate AX.25 support is enabled.
  29. CD Appropriate CD support is enabled.
  30. DRM Direct Rendering Management support is enabled.
  31. EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
  32. EFI EFI Partitioning (GPT) is enabled
  33. EIDE EIDE/ATAPI support is enabled.
  34. FB The frame buffer device is enabled.
  35. HW Appropriate hardware is enabled.
  36. IA-32 IA-32 aka i386 architecture is enabled.
  37. IA-64 IA-64 architecture is enabled.
  38. IOSCHED More than one I/O scheduler is enabled.
  39. IP_PNP IP DHCP, BOOTP, or RARP is enabled.
  40. ISAPNP ISA PnP code is enabled.
  41. ISDN Appropriate ISDN support is enabled.
  42. JOY Appropriate joystick support is enabled.
  43. LIBATA Libata driver is enabled
  44. LP Printer support is enabled.
  45. LOOP Loopback device support is enabled.
  46. M68k M68k architecture is enabled.
  47. These options have more detailed description inside of
  48. Documentation/m68k/kernel-options.txt.
  49. MCA MCA bus support is enabled.
  50. MDA MDA console support is enabled.
  51. MOUSE Appropriate mouse support is enabled.
  52. MSI Message Signaled Interrupts (PCI).
  53. MTD MTD support is enabled.
  54. NET Appropriate network support is enabled.
  55. NUMA NUMA support is enabled.
  56. GENERIC_TIME The generic timeofday code is enabled.
  57. NFS Appropriate NFS support is enabled.
  58. OSS OSS sound support is enabled.
  59. PV_OPS A paravirtualized kernel
  60. PARIDE The ParIDE subsystem is enabled.
  61. PARISC The PA-RISC architecture is enabled.
  62. PCI PCI bus support is enabled.
  63. PCMCIA The PCMCIA subsystem is enabled.
  64. PNP Plug & Play support is enabled.
  65. PPC PowerPC architecture is enabled.
  66. PPT Parallel port support is enabled.
  67. PS2 Appropriate PS/2 support is enabled.
  68. RAM RAM disk support is enabled.
  69. S390 S390 architecture is enabled.
  70. SCSI Appropriate SCSI support is enabled.
  71. A lot of drivers has their options described inside of
  72. Documentation/scsi/.
  73. SELINUX SELinux support is enabled.
  74. SERIAL Serial support is enabled.
  75. SH SuperH architecture is enabled.
  76. SMP The kernel is an SMP kernel.
  77. SPARC Sparc architecture is enabled.
  78. SWSUSP Software suspend is enabled.
  79. TS Appropriate touchscreen support is enabled.
  80. USB USB support is enabled.
  81. USBHID USB Human Interface Device support is enabled.
  82. V4L Video For Linux support is enabled.
  83. VGA The VGA console has been enabled.
  84. VT Virtual terminal support is enabled.
  85. WDT Watchdog support is enabled.
  86. XT IBM PC/XT MFM hard disk support is enabled.
  87. X86-64 X86-64 architecture is enabled.
  88. More X86-64 boot options can be found in
  89. Documentation/x86_64/boot-options.txt .
  90. In addition, the following text indicates that the option:
  91. BUGS= Relates to possible processor bugs on the said processor.
  92. KNL Is a kernel start-up parameter.
  93. BOOT Is a boot loader parameter.
  94. Parameters denoted with BOOT are actually interpreted by the boot
  95. loader, and have no meaning to the kernel directly.
  96. Do not modify the syntax of boot loader parameters without extreme
  97. need or coordination with <Documentation/i386/boot.txt>.
  98. There are also arch-specific kernel-parameters not documented here.
  99. See for example <Documentation/x86_64/boot-options.txt>.
  100. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
  101. a trailing = on the name of any parameter states that that parameter will
  102. be entered as an environment variable, whereas its absence indicates that
  103. it will appear as a kernel argument readable via /proc/cmdline by programs
  104. running once the system is up.
  105. The number of kernel parameters is not limited, but the length of the
  106. complete command line (parameters including spaces etc.) is limited to
  107. a fixed number of characters. This limit depends on the architecture
  108. and is between 256 and 4096 characters. It is defined in the file
  109. ./include/asm/setup.h as COMMAND_LINE_SIZE.
  110. 53c7xx= [HW,SCSI] Amiga SCSI controllers
  111. See header of drivers/scsi/53c7xx.c.
  112. See also Documentation/scsi/ncr53c7xx.txt.
  113. acpi= [HW,ACPI,X86-64,i386]
  114. Advanced Configuration and Power Interface
  115. Format: { force | off | ht | strict | noirq }
  116. force -- enable ACPI if default was off
  117. off -- disable ACPI if default was on
  118. noirq -- do not use ACPI for IRQ routing
  119. ht -- run only enough ACPI to enable Hyper Threading
  120. strict -- Be less tolerant of platforms that are not
  121. strictly ACPI specification compliant.
  122. See also Documentation/pm.txt, pci=noacpi
  123. acpi_apic_instance= [ACPI, IOAPIC]
  124. Format: <int>
  125. 2: use 2nd APIC table, if available
  126. 1,0: use 1st APIC table
  127. default: 0
  128. acpi_sleep= [HW,ACPI] Sleep options
  129. Format: { s3_bios, s3_mode }
  130. See Documentation/power/video.txt
  131. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
  132. Format: { level | edge | high | low }
  133. acpi_irq_balance [HW,ACPI]
  134. ACPI will balance active IRQs
  135. default in APIC mode
  136. acpi_irq_nobalance [HW,ACPI]
  137. ACPI will not move active IRQs (default)
  138. default in PIC mode
  139. acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
  140. use by PCI
  141. Format: <irq>,<irq>...
  142. acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
  143. Format: <irq>,<irq>...
  144. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
  145. Format: To spoof as Windows 98: ="Microsoft Windows"
  146. acpi_osi= [HW,ACPI] empty param disables _OSI
  147. acpi_serialize [HW,ACPI] force serialization of AML methods
  148. acpi_skip_timer_override [HW,ACPI]
  149. Recognize and ignore IRQ0/pin2 Interrupt Override.
  150. For broken nForce2 BIOS resulting in XT-PIC timer.
  151. acpi_use_timer_override [HW,ACPI}
  152. Use timer override. For some broken Nvidia NF5 boards
  153. that require a timer override, but don't have
  154. HPET
  155. acpi.debug_layer= [HW,ACPI]
  156. Format: <int>
  157. Each bit of the <int> indicates an ACPI debug layer,
  158. 1: enable, 0: disable. It is useful for boot time
  159. debugging. After system has booted up, it can be set
  160. via /sys/module/acpi/parameters/debug_layer.
  161. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  162. Available bits (add the numbers together) to enable debug output
  163. for specific parts of the ACPI subsystem:
  164. 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
  165. 0x10 namespace 0x20 parser 0x40 dispatcher
  166. 0x80 executer 0x100 resources 0x200 acpica debugger
  167. 0x400 os services 0x800 acpica disassembler.
  168. The number can be in decimal or prefixed with 0x in hex.
  169. Warning: Many of these options can produce a lot of
  170. output and make your system unusable. Be very careful.
  171. acpi.debug_level= [HW,ACPI]
  172. Format: <int>
  173. Each bit of the <int> indicates an ACPI debug level,
  174. 1: enable, 0: disable. It is useful for boot time
  175. debugging. After system has booted up, it can be set
  176. via /sys/module/acpi/parameters/debug_level.
  177. CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
  178. Available bits (add the numbers together) to enable different
  179. debug output levels of the ACPI subsystem:
  180. 0x01 error 0x02 warn 0x04 init 0x08 debug object
  181. 0x10 info 0x20 init names 0x40 parse 0x80 load
  182. 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
  183. 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
  184. 0x10000 resources 0x20000 user requests 0x40000 package.
  185. The number can be in decimal or prefixed with 0x in hex.
  186. Warning: Many of these options can produce a lot of
  187. output and make your system unusable. Be very careful.
  188. acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
  189. acpi_generic_hotkey [HW,ACPI]
  190. Allow consolidated generic hotkey driver to
  191. override platform specific driver.
  192. See also Documentation/acpi-hotkey.txt.
  193. acpi_pm_good [IA-32,X86-64]
  194. Override the pmtimer bug detection: force the kernel
  195. to assume that this machine's pmtimer latches its value
  196. and always returns good values.
  197. enable_timer_pin_1 [i386,x86-64]
  198. Enable PIN 1 of APIC timer
  199. Can be useful to work around chipset bugs
  200. (in particular on some ATI chipsets).
  201. The kernel tries to set a reasonable default.
  202. disable_timer_pin_1 [i386,x86-64]
  203. Disable PIN 1 of APIC timer
  204. Can be useful to work around chipset bugs.
  205. ad1816= [HW,OSS]
  206. Format: <io>,<irq>,<dma>,<dma2>
  207. See also Documentation/sound/oss/AD1816.
  208. ad1848= [HW,OSS]
  209. Format: <io>,<irq>,<dma>,<dma2>,<type>
  210. adlib= [HW,OSS]
  211. Format: <io>
  212. advansys= [HW,SCSI]
  213. See header of drivers/scsi/advansys.c.
  214. advwdt= [HW,WDT] Advantech WDT
  215. Format: <iostart>,<iostop>
  216. aedsp16= [HW,OSS] Audio Excel DSP 16
  217. Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
  218. See also header of sound/oss/aedsp16.c.
  219. aha152x= [HW,SCSI]
  220. See Documentation/scsi/aha152x.txt.
  221. aha1542= [HW,SCSI]
  222. Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
  223. aic7xxx= [HW,SCSI]
  224. See Documentation/scsi/aic7xxx.txt.
  225. aic79xx= [HW,SCSI]
  226. See Documentation/scsi/aic79xx.txt.
  227. amijoy.map= [HW,JOY] Amiga joystick support
  228. Map of devices attached to JOY0DAT and JOY1DAT
  229. Format: <a>,<b>
  230. See also Documentation/kernel/input/joystick.txt
  231. analog.map= [HW,JOY] Analog joystick and gamepad support
  232. Specifies type or capabilities of an analog joystick
  233. connected to one of 16 gameports
  234. Format: <type1>,<type2>,..<type16>
  235. apc= [HW,SPARC]
  236. Power management functions (SPARCstation-4/5 + deriv.)
  237. Format: noidle
  238. Disable APC CPU standby support. SPARCstation-Fox does
  239. not play well with APC CPU idle - disable it if you have
  240. APC and your system crashes randomly.
  241. apic= [APIC,i386] Change the output verbosity whilst booting
  242. Format: { quiet (default) | verbose | debug }
  243. Change the amount of debugging information output
  244. when initialising the APIC and IO-APIC components.
  245. apm= [APM] Advanced Power Management
  246. See header of arch/i386/kernel/apm.c.
  247. applicom= [HW]
  248. Format: <mem>,<irq>
  249. arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
  250. Format: <io>,<irq>,<nodeID>
  251. ataflop= [HW,M68k]
  252. atarimouse= [HW,MOUSE] Atari Mouse
  253. atascsi= [HW,SCSI] Atari SCSI
  254. atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
  255. EzKey and similar keyboards
  256. atkbd.reset= [HW] Reset keyboard during initialization
  257. atkbd.set= [HW] Select keyboard code set
  258. Format: <int> (2 = AT (default), 3 = PS/2)
  259. atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
  260. keyboards
  261. atkbd.softraw= [HW] Choose between synthetic and real raw mode
  262. Format: <bool> (0 = real, 1 = synthetic (default))
  263. atkbd.softrepeat= [HW]
  264. Use software keyboard repeat
  265. autotest [IA64]
  266. aztcd= [HW,CD] Aztech CD268 CDROM driver
  267. Format: <io>,0x79 (?)
  268. baycom_epp= [HW,AX25]
  269. Format: <io>,<mode>
  270. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
  271. Format: <io>,<mode>
  272. See header of drivers/net/hamradio/baycom_par.c.
  273. baycom_ser_fdx= [HW,AX25]
  274. BayCom Serial Port AX.25 Modem (Full Duplex Mode)
  275. Format: <io>,<irq>,<mode>[,<baud>]
  276. See header of drivers/net/hamradio/baycom_ser_fdx.c.
  277. baycom_ser_hdx= [HW,AX25]
  278. BayCom Serial Port AX.25 Modem (Half Duplex Mode)
  279. Format: <io>,<irq>,<mode>
  280. See header of drivers/net/hamradio/baycom_ser_hdx.c.
  281. blkmtd_device= [HW,MTD]
  282. blkmtd_erasesz=
  283. blkmtd_ro=
  284. blkmtd_bs=
  285. blkmtd_count=
  286. bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
  287. bttv.radio= Most important insmod options are available as
  288. kernel args too.
  289. bttv.pll= See Documentation/video4linux/bttv/Insmod-options
  290. bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
  291. BusLogic= [HW,SCSI]
  292. See drivers/scsi/BusLogic.c, comment before function
  293. BusLogic_ParseDriverOptions().
  294. c101= [NET] Moxa C101 synchronous serial card
  295. cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
  296. Sometimes CPU hardware bugs make them report the cache
  297. size incorrectly. The kernel will attempt work arounds
  298. to fix known problems, but for some CPUs it is not
  299. possible to determine what the correct size should be.
  300. This option provides an override for these situations.
  301. cdu31a= [HW,CD]
  302. Format: <io>,<irq>[,PAS]
  303. See header of drivers/cdrom/cdu31a.c.
  304. chandev= [HW,NET] Generic channel device initialisation
  305. checkreqprot [SELINUX] Set initial checkreqprot flag value.
  306. Format: { "0" | "1" }
  307. See security/selinux/Kconfig help text.
  308. 0 -- check protection applied by kernel (includes
  309. any implied execute protection).
  310. 1 -- check protection requested by application.
  311. Default value is set via a kernel config option.
  312. Value can be changed at runtime via
  313. /selinux/checkreqprot.
  314. clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
  315. [Deprecated]
  316. Forces specified clocksource (if available) to be used
  317. when calculating gettimeofday(). If specified
  318. clocksource is not available, it defaults to PIT.
  319. Format: { pit | tsc | cyclone | pmtmr }
  320. code_bytes [IA32] How many bytes of object code to print in an
  321. oops report.
  322. Range: 0 - 8192
  323. Default: 64
  324. disable_8254_timer
  325. enable_8254_timer
  326. [IA32/X86_64] Disable/Enable interrupt 0 timer routing
  327. over the 8254 in addition to over the IO-APIC. The
  328. kernel tries to set a sensible default.
  329. hpet= [IA-32,HPET] option to disable HPET and use PIT.
  330. Format: disable
  331. cm206= [HW,CD]
  332. Format: { auto | [<io>,][<irq>] }
  333. com20020= [HW,NET] ARCnet - COM20020 chipset
  334. Format:
  335. <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
  336. com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
  337. Format: <io>[,<irq>]
  338. com90xx= [HW,NET]
  339. ARCnet - COM90xx chipset (memory-mapped buffers)
  340. Format: <io>[,<irq>[,<memstart>]]
  341. condev= [HW,S390] console device
  342. conmode=
  343. console= [KNL] Output console device and options.
  344. tty<n> Use the virtual console device <n>.
  345. ttyS<n>[,options]
  346. ttyUSB0[,options]
  347. Use the specified serial port. The options are of
  348. the form "bbbbpnf", where "bbbb" is the baud rate,
  349. "p" is parity ("n", "o", or "e"), "n" is number of
  350. bits, and "f" is flow control ("r" for RTS or
  351. omit it). Default is "9600n8".
  352. See Documentation/serial-console.txt for more
  353. information. See
  354. Documentation/networking/netconsole.txt for an
  355. alternative.
  356. uart,io,<addr>[,options]
  357. uart,mmio,<addr>[,options]
  358. Start an early, polled-mode console on the 8250/16550
  359. UART at the specified I/O port or MMIO address,
  360. switching to the matching ttyS device later. The
  361. options are the same as for ttyS, above.
  362. cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
  363. Format:
  364. <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
  365. cpia_pp= [HW,PPT]
  366. Format: { parport<nr> | auto | none }
  367. crashkernel=nn[KMG]@ss[KMG]
  368. [KNL] Reserve a chunk of physical memory to
  369. hold a kernel to switch to with kexec on panic.
  370. cs4232= [HW,OSS]
  371. Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
  372. cs89x0_dma= [HW,NET]
  373. Format: <dma>
  374. cs89x0_media= [HW,NET]
  375. Format: { rj45 | aui | bnc }
  376. cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
  377. dasd= [HW,NET]
  378. See header of drivers/s390/block/dasd_devmap.c.
  379. db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
  380. (one device per port)
  381. Format: <port#>,<type>
  382. See also Documentation/input/joystick-parport.txt
  383. debug [KNL] Enable kernel debugging (events log level).
  384. debug_locks_verbose=
  385. [KNL] verbose self-tests
  386. Format=<0|1>
  387. Print debugging info while doing the locking API
  388. self-tests.
  389. We default to 0 (no extra messages), setting it to
  390. 1 will print _a lot_ more information - normally
  391. only useful to kernel developers.
  392. decnet= [HW,NET]
  393. Format: <area>[,<node>]
  394. See also Documentation/networking/decnet.txt.
  395. default_blu= [VT]
  396. Format: <blue0>,<blue1>,<blue2>,...,<blue15>
  397. Change the default blue palette of the console.
  398. This is a 16-member array composed of values
  399. ranging from 0-255.
  400. default_grn= [VT]
  401. Format: <green0>,<green1>,<green2>,...,<green15>
  402. Change the default green palette of the console.
  403. This is a 16-member array composed of values
  404. ranging from 0-255.
  405. default_red= [VT]
  406. Format: <red0>,<red1>,<red2>,...,<red15>
  407. Change the default red palette of the console.
  408. This is a 16-member array composed of values
  409. ranging from 0-255.
  410. default_utf8= [VT]
  411. Format=<0|1>
  412. Set system-wide default UTF-8 mode for all tty's.
  413. Default is 0 and by setting to 1, it enables UTF-8
  414. mode for all newly opened or allocated terminals.
  415. dhash_entries= [KNL]
  416. Set number of hash buckets for dentry cache.
  417. digi= [HW,SERIAL]
  418. IO parameters + enable/disable command.
  419. digiepca= [HW,SERIAL]
  420. See drivers/char/README.epca and
  421. Documentation/digiepca.txt.
  422. dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
  423. support available.
  424. Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
  425. dmasound= [HW,OSS] Sound subsystem buffers
  426. dscc4.setup= [NET]
  427. dtc3181e= [HW,SCSI]
  428. earlyprintk= [IA-32,X86-64,SH]
  429. earlyprintk=vga
  430. earlyprintk=serial[,ttySn[,baudrate]]
  431. Append ",keep" to not disable it when the real console
  432. takes over.
  433. Only vga or serial at a time, not both.
  434. Currently only ttyS0 and ttyS1 are supported.
  435. Interaction with the standard serial driver is not
  436. very good.
  437. The VGA output is eventually overwritten by the real
  438. console.
  439. eata= [HW,SCSI]
  440. ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
  441. Format: <int>
  442. 0: polling mode
  443. non-0: interrupt mode (default)
  444. eda= [HW,PS2]
  445. edb= [HW,PS2]
  446. edd= [EDD]
  447. Format: {"of[f]" | "sk[ipmbr]"}
  448. See comment in arch/i386/boot/edd.S
  449. eicon= [HW,ISDN]
  450. Format: <id>,<membase>,<irq>
  451. eisa_irq_edge= [PARISC,HW]
  452. See header of drivers/parisc/eisa.c.
  453. elanfreq= [IA-32]
  454. See comment before function elanfreq_setup() in
  455. arch/i386/kernel/cpu/cpufreq/elanfreq.c.
  456. elevator= [IOSCHED]
  457. Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
  458. See Documentation/block/as-iosched.txt and
  459. Documentation/block/deadline-iosched.txt for details.
  460. elfcorehdr= [IA-32, X86_64]
  461. Specifies physical address of start of kernel core
  462. image elf header. Generally kexec loader will
  463. pass this option to capture kernel.
  464. See Documentation/kdump/kdump.txt for details.
  465. enforcing [SELINUX] Set initial enforcing status.
  466. Format: {"0" | "1"}
  467. See security/selinux/Kconfig help text.
  468. 0 -- permissive (log only, no denials).
  469. 1 -- enforcing (deny and log).
  470. Default value is 0.
  471. Value can be changed at runtime via /selinux/enforce.
  472. es1371= [HW,OSS]
  473. Format: <spdif>,[<nomix>,[<amplifier>]]
  474. See also header of sound/oss/es1371.c.
  475. ether= [HW,NET] Ethernet cards parameters
  476. This option is obsoleted by the "netdev=" option, which
  477. has equivalent usage. See its documentation for details.
  478. eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
  479. Format: <io>[,<irq>]
  480. failslab=
  481. fail_page_alloc=
  482. fail_make_request=[KNL]
  483. General fault injection mechanism.
  484. Format: <interval>,<probability>,<space>,<times>
  485. See also /Documentation/fault-injection/.
  486. fd_mcs= [HW,SCSI]
  487. See header of drivers/scsi/fd_mcs.c.
  488. fdomain= [HW,SCSI]
  489. See header of drivers/scsi/fdomain.c.
  490. floppy= [HW]
  491. See Documentation/floppy.txt.
  492. gamecon.map[2|3]=
  493. [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
  494. support via parallel port (up to 5 devices per port)
  495. Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
  496. See also Documentation/input/joystick-parport.txt
  497. gamma= [HW,DRM]
  498. gdth= [HW,SCSI]
  499. See header of drivers/scsi/gdth.c.
  500. gpt [EFI] Forces disk with valid GPT signature but
  501. invalid Protective MBR to be treated as GPT.
  502. gscd= [HW,CD]
  503. Format: <io>
  504. gvp11= [HW,SCSI]
  505. hashdist= [KNL,NUMA] Large hashes allocated during boot
  506. are distributed across NUMA nodes. Defaults on
  507. for IA-64, off otherwise.
  508. Format: 0 | 1 (for off | on)
  509. hcl= [IA-64] SGI's Hardware Graph compatibility layer
  510. hd= [EIDE] (E)IDE hard drive subsystem geometry
  511. Format: <cyl>,<head>,<sect>
  512. hd?= [HW] (E)IDE subsystem
  513. hd?lun= See Documentation/ide.txt.
  514. highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
  515. size of <nn>. This works even on boxes that have no
  516. highmem otherwise. This also works to reduce highmem
  517. size on bigger boxes.
  518. highres= [KNL] Enable/disable high resolution timer mode.
  519. Valid parameters: "on", "off"
  520. Default: "on"
  521. hisax= [HW,ISDN]
  522. See Documentation/isdn/README.HiSax.
  523. hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
  524. i8042.direct [HW] Put keyboard port into non-translated mode
  525. i8042.dumbkbd [HW] Pretend that controller can only read data from
  526. keyboard and cannot control its state
  527. (Don't attempt to blink the leds)
  528. i8042.noaux [HW] Don't check for auxiliary (== mouse) port
  529. i8042.nokbd [HW] Don't check/create keyboard port
  530. i8042.nomux [HW] Don't check presence of an active multiplexing
  531. controller
  532. i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
  533. controllers
  534. i8042.panicblink=
  535. [HW] Frequency with which keyboard LEDs should blink
  536. when kernel panics (default is 0.5 sec)
  537. i8042.reset [HW] Reset the controller during init and cleanup
  538. i8042.unlock [HW] Unlock (ignore) the keylock
  539. i810= [HW,DRM]
  540. i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
  541. indicates that the driver is running on unsupported
  542. hardware.
  543. i8k.force [HW] Activate i8k driver even if SMM BIOS signature
  544. does not match list of supported models.
  545. i8k.power_status
  546. [HW] Report power status in /proc/i8k
  547. (disabled by default)
  548. i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
  549. capability is set.
  550. ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
  551. See Documentation/mca.txt.
  552. icn= [HW,ISDN]
  553. Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
  554. ide= [HW] (E)IDE subsystem
  555. Format: ide=nodma or ide=doubler or ide=reverse
  556. See Documentation/ide.txt.
  557. ide?= [HW] (E)IDE subsystem
  558. Format: ide?=noprobe or chipset specific parameters.
  559. See Documentation/ide.txt.
  560. idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
  561. See Documentation/ide.txt.
  562. idle= [X86]
  563. Format: idle=poll or idle=mwait
  564. Poll forces a polling idle loop that can slightly improves the performance
  565. of waking up a idle CPU, but will use a lot of power and make the system
  566. run hot. Not recommended.
  567. idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
  568. to not use it because it doesn't save as much power as a normal idle
  569. loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
  570. as idle=poll.
  571. ignore_loglevel [KNL]
  572. Ignore loglevel setting - this will print /all/
  573. kernel messages to the console. Useful for debugging.
  574. ihash_entries= [KNL]
  575. Set number of hash buckets for inode cache.
  576. in2000= [HW,SCSI]
  577. See header of drivers/scsi/in2000.c.
  578. init= [KNL]
  579. Format: <full_path>
  580. Run specified binary instead of /sbin/init as init
  581. process.
  582. initcall_debug [KNL] Trace initcalls as they are executed. Useful
  583. for working out where the kernel is dying during
  584. startup.
  585. initrd= [BOOT] Specify the location of the initial ramdisk
  586. inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
  587. Format: <irq>
  588. inttest= [IA64]
  589. io7= [HW] IO7 for Marvel based alpha systems
  590. See comment before marvel_specify_io7 in
  591. arch/alpha/kernel/core_marvel.c.
  592. ip= [IP_PNP]
  593. See Documentation/nfsroot.txt.
  594. ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
  595. See comment before ip2_setup() in drivers/char/ip2.c.
  596. ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
  597. See header of drivers/scsi/ips.c.
  598. ports= [IP_VS_FTP] IPVS ftp helper module
  599. Default is 21.
  600. Up to 8 (IP_VS_APP_MAX_PORTS) ports
  601. may be specified.
  602. Format: <port>,<port>....
  603. irqfixup [HW]
  604. When an interrupt is not handled search all handlers
  605. for it. Intended to get systems with badly broken
  606. firmware running.
  607. irqpoll [HW]
  608. When an interrupt is not handled search all handlers
  609. for it. Also check all handlers each timer
  610. interrupt. Intended to get systems with badly broken
  611. firmware running.
  612. isapnp= [ISAPNP]
  613. Format: <RDP>,<reset>,<pci_scan>,<verbosity>
  614. isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
  615. Format:
  616. <cpu number>,...,<cpu number>
  617. or
  618. <cpu number>-<cpu number> (must be a positive range in ascending order)
  619. or a mixture
  620. <cpu number>,...,<cpu number>-<cpu number>
  621. This option can be used to specify one or more CPUs
  622. to isolate from the general SMP balancing and scheduling
  623. algorithms. The only way to move a process onto or off
  624. an "isolated" CPU is via the CPU affinity syscalls.
  625. <cpu number> begins at 0 and the maximum value is
  626. "number of CPUs in system - 1".
  627. This option is the preferred way to isolate CPUs. The
  628. alternative -- manually setting the CPU mask of all
  629. tasks in the system -- can cause problems and
  630. suboptimal load balancer performance.
  631. isp16= [HW,CD]
  632. Format: <io>,<irq>,<dma>,<setup>
  633. iucv= [HW,NET]
  634. js= [HW,JOY] Analog joystick
  635. See Documentation/input/joystick.txt.
  636. keepinitrd [HW,ARM]
  637. kstack=N [IA-32,X86-64] Print N words from the kernel stack
  638. in oops dumps.
  639. l2cr= [PPC]
  640. lapic [IA-32,APIC] Enable the local APIC even if BIOS
  641. disabled it.
  642. lapic_timer_c2_ok [IA-32,x86-64,APIC] trust the local apic timer in
  643. C2 power state.
  644. lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
  645. Format: addr:<io>,irq:<irq>
  646. legacy_serial.force [HW,IA-32,X86-64]
  647. Probe for COM ports at legacy addresses even
  648. if PNPBIOS or ACPI should describe them. This
  649. is for working around firmware defects.
  650. llsc*= [IA64] See function print_params() in
  651. arch/ia64/sn/kernel/llsc4.c.
  652. load_ramdisk= [RAM] List of ramdisks to load from floppy
  653. See Documentation/ramdisk.txt.
  654. lockd.nlm_grace_period=P [NFS] Assign grace period.
  655. Format: <integer>
  656. lockd.nlm_tcpport=N [NFS] Assign TCP port.
  657. Format: <integer>
  658. lockd.nlm_timeout=T [NFS] Assign timeout value.
  659. Format: <integer>
  660. lockd.nlm_udpport=M [NFS] Assign UDP port.
  661. Format: <integer>
  662. logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
  663. Format: <irq>
  664. loglevel= All Kernel Messages with a loglevel smaller than the
  665. console loglevel will be printed to the console. It can
  666. also be changed with klogd or other programs. The
  667. loglevels are defined as follows:
  668. 0 (KERN_EMERG) system is unusable
  669. 1 (KERN_ALERT) action must be taken immediately
  670. 2 (KERN_CRIT) critical conditions
  671. 3 (KERN_ERR) error conditions
  672. 4 (KERN_WARNING) warning conditions
  673. 5 (KERN_NOTICE) normal but significant condition
  674. 6 (KERN_INFO) informational
  675. 7 (KERN_DEBUG) debug-level messages
  676. log_buf_len=n Sets the size of the printk ring buffer, in bytes.
  677. Format: { n | nk | nM }
  678. n must be a power of two. The default size
  679. is set in the kernel config file.
  680. lp=0 [LP] Specify parallel ports to use, e.g,
  681. lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
  682. lp=reset first parallel port). 'lp=0' disables the
  683. lp=auto printer driver. 'lp=reset' (which can be
  684. specified in addition to the ports) causes
  685. attached printers to be reset. Using
  686. lp=port1,port2,... specifies the parallel ports
  687. to associate lp devices with, starting with
  688. lp0. A port specification may be 'none' to skip
  689. that lp device, or a parport name such as
  690. 'parport0'. Specifying 'lp=auto' instead of a
  691. port specification list means that device IDs
  692. from each port should be examined, to see if
  693. an IEEE 1284-compliant printer is attached; if
  694. so, the driver will manage that printer.
  695. See also header of drivers/char/lp.c.
  696. lpj=n [KNL]
  697. Sets loops_per_jiffy to given constant, thus avoiding
  698. time-consuming boot-time autodetection (up to 250 ms per
  699. CPU). 0 enables autodetection (default). To determine
  700. the correct value for your kernel, boot with normal
  701. autodetection and see what value is printed. Note that
  702. on SMP systems the preset will be applied to all CPUs,
  703. which is likely to cause problems if your CPUs need
  704. significantly divergent settings. An incorrect value
  705. will cause delays in the kernel to be wrong, leading to
  706. unpredictable I/O errors and other breakage. Although
  707. unlikely, in the extreme case this might damage your
  708. hardware.
  709. ltpc= [NET]
  710. Format: <io>,<irq>,<dma>
  711. mac5380= [HW,SCSI] Format:
  712. <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  713. mac53c9x= [HW,SCSI] Format:
  714. <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
  715. machvec= [IA64] Force the use of a particular machine-vector
  716. (machvec) in a generic kernel.
  717. Example: machvec=hpzx1_swiotlb
  718. max_loop= [LOOP] Maximum number of loopback devices that can
  719. be mounted
  720. Format: <1-256>
  721. maxcpus= [SMP] Maximum number of processors that an SMP kernel
  722. should make use of.
  723. Using "nosmp" or "maxcpus=0" will disable SMP
  724. entirely (the MPS table probe still happens, though).
  725. A command-line option of "maxcpus=<NUM>", where <NUM>
  726. is an integer greater than 0, limits the maximum number
  727. of CPUs activated in SMP mode to <NUM>.
  728. Using "maxcpus=1" on an SMP kernel is the trivial
  729. case of an SMP kernel with only one CPU.
  730. max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
  731. equal to this physical address is ignored.
  732. max_luns= [SCSI] Maximum number of LUNs to probe.
  733. Should be between 1 and 2^32-1.
  734. max_report_luns=
  735. [SCSI] Maximum number of LUNs received.
  736. Should be between 1 and 16384.
  737. mca-pentium [BUGS=IA-32]
  738. mcatest= [IA-64]
  739. mcd= [HW,CD]
  740. Format: <port>,<irq>,<mitsumi_bug_93_wait>
  741. mcdx= [HW,CD]
  742. mce [IA-32] Machine Check Exception
  743. md= [HW] RAID subsystems devices and level
  744. See Documentation/md.txt.
  745. mdacon= [MDA]
  746. Format: <first>,<last>
  747. Specifies range of consoles to be captured by the MDA.
  748. mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
  749. Amount of memory to be used when the kernel is not able
  750. to see the whole system memory or for test.
  751. [IA-32] Use together with memmap= to avoid physical
  752. address space collisions. Without memmap= PCI devices
  753. could be placed at addresses belonging to unused RAM.
  754. mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
  755. memory.
  756. memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
  757. E820 memory map, as specified by the user.
  758. Such memmap=exactmap lines can be constructed based on
  759. BIOS output or other requirements. See the memmap=nn@ss
  760. option description.
  761. memmap=nn[KMG]@ss[KMG]
  762. [KNL] Force usage of a specific region of memory
  763. Region of memory to be used, from ss to ss+nn.
  764. memmap=nn[KMG]#ss[KMG]
  765. [KNL,ACPI] Mark specific memory as ACPI data.
  766. Region of memory to be used, from ss to ss+nn.
  767. memmap=nn[KMG]$ss[KMG]
  768. [KNL,ACPI] Mark specific memory as reserved.
  769. Region of memory to be used, from ss to ss+nn.
  770. meye.*= [HW] Set MotionEye Camera parameters
  771. See Documentation/video4linux/meye.txt.
  772. mga= [HW,DRM]
  773. migration_cost=
  774. [KNL,SMP] debug: override scheduler migration costs
  775. Format: <level-1-usecs>,<level-2-usecs>,...
  776. This debugging option can be used to override the
  777. default scheduler migration cost matrix. The numbers
  778. are indexed by 'CPU domain distance'.
  779. E.g. migration_cost=1000,2000,3000 on an SMT NUMA
  780. box will set up an intra-core migration cost of
  781. 1 msec, an inter-core migration cost of 2 msecs,
  782. and an inter-node migration cost of 3 msecs.
  783. WARNING: using the wrong values here can break
  784. scheduler performance, so it's only for scheduler
  785. development purposes, not production environments.
  786. migration_debug=
  787. [KNL,SMP] migration cost auto-detect verbosity
  788. Format=<0|1|2>
  789. If a system's migration matrix reported at bootup
  790. seems erroneous then this option can be used to
  791. increase verbosity of the detection process.
  792. We default to 0 (no extra messages), 1 will print
  793. some more information, and 2 will be really
  794. verbose (probably only useful if you also have a
  795. serial console attached to the system).
  796. migration_factor=
  797. [KNL,SMP] multiply/divide migration costs by a factor
  798. Format=<percent>
  799. This debug option can be used to proportionally
  800. increase or decrease the auto-detected migration
  801. costs for all entries of the migration matrix.
  802. E.g. migration_factor=150 will increase migration
  803. costs by 50%. (and thus the scheduler will be less
  804. eager migrating cache-hot tasks)
  805. migration_factor=80 will decrease migration costs
  806. by 20%. (thus the scheduler will be more eager to
  807. migrate tasks)
  808. WARNING: using the wrong values here can break
  809. scheduler performance, so it's only for scheduler
  810. development purposes, not production environments.
  811. mousedev.tap_time=
  812. [MOUSE] Maximum time between finger touching and
  813. leaving touchpad surface for touch to be considered
  814. a tap and be reported as a left button click (for
  815. touchpads working in absolute mode only).
  816. Format: <msecs>
  817. mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
  818. reporting absolute coordinates, such as tablets
  819. mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
  820. reporting absolute coordinates, such as tablets
  821. mpu401= [HW,OSS]
  822. Format: <io>,<irq>
  823. MTD_Partition= [MTD]
  824. Format: <name>,<region-number>,<size>,<offset>
  825. MTD_Region= [MTD] Format:
  826. <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
  827. mtdparts= [MTD]
  828. See drivers/mtd/cmdline.c.
  829. mtouchusb.raw_coordinates=
  830. [HW] Make the MicroTouch USB driver use raw coordinates
  831. ('y', default) or cooked coordinates ('n')
  832. n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
  833. NCR_D700= [HW,SCSI]
  834. See header of drivers/scsi/NCR_D700.c.
  835. ncr5380= [HW,SCSI]
  836. ncr53c400= [HW,SCSI]
  837. ncr53c400a= [HW,SCSI]
  838. ncr53c406a= [HW,SCSI]
  839. ncr53c8xx= [HW,SCSI]
  840. netdev= [NET] Network devices parameters
  841. Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
  842. Note that mem_start is often overloaded to mean
  843. something different and driver-specific.
  844. This usage is only documented in each driver source
  845. file if at all.
  846. nfsaddrs= [NFS]
  847. See Documentation/nfsroot.txt.
  848. nfsroot= [NFS] nfs root filesystem for disk-less boxes.
  849. See Documentation/nfsroot.txt.
  850. nfs.callback_tcpport=
  851. [NFS] set the TCP port on which the NFSv4 callback
  852. channel should listen.
  853. nfs.idmap_cache_timeout=
  854. [NFS] set the maximum lifetime for idmapper cache
  855. entries.
  856. nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
  857. no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
  858. emulation library even if a 387 maths coprocessor
  859. is present.
  860. noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
  861. when set.
  862. Format: <int>
  863. noaliencache [MM, NUMA] Disables the allcoation of alien caches in
  864. the slab allocator. Saves per-node memory, but will
  865. impact performance on real NUMA hardware.
  866. noalign [KNL,ARM]
  867. noapic [SMP,APIC] Tells the kernel to not make use of any
  868. IOAPICs that may be present in the system.
  869. noasync [HW,M68K] Disables async and sync negotiation for
  870. all devices.
  871. nobats [PPC] Do not use BATs for mapping kernel lowmem
  872. on "Classic" PPC cores.
  873. nocache [ARM]
  874. nodelayacct [KNL] Disable per-task delay accounting
  875. nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
  876. noexec [IA-64]
  877. noexec [IA-32,X86-64]
  878. noexec=on: enable non-executable mappings (default)
  879. noexec=off: disable nn-executable mappings
  880. nofxsr [BUGS=IA-32] Disables x86 floating point extended
  881. register save and restore. The kernel will only save
  882. legacy floating-point registers on task switch.
  883. nohlt [BUGS=ARM]
  884. no-hlt [BUGS=IA-32] Tells the kernel that the hlt
  885. instruction doesn't work correctly and not to
  886. use it.
  887. nohalt [IA-64] Tells the kernel not to use the power saving
  888. function PAL_HALT_LIGHT when idle. This increases
  889. power-consumption. On the positive side, it reduces
  890. interrupt wake-up latency, which may improve performance
  891. in certain environments such as networked servers or
  892. real-time systems.
  893. nohz= [KNL] Boottime enable/disable dynamic ticks
  894. Valid arguments: on, off
  895. Default: on
  896. noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
  897. noirqdebug [IA-32] Disables the code which attempts to detect and
  898. disable unhandled interrupt sources.
  899. no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
  900. broken timer IRQ sources.
  901. noisapnp [ISAPNP] Disables ISA PnP code.
  902. noinitrd [RAM] Tells the kernel not to load any configured
  903. initial RAM disk.
  904. nointroute [IA-64]
  905. nolapic [IA-32,APIC] Do not enable or use the local APIC.
  906. nolapic_timer [IA-32,APIC] Do not use the local APIC timer.
  907. noltlbs [PPC] Do not use large page/tlb entries for kernel
  908. lowmem mapping on PPC40x.
  909. nomca [IA-64] Disable machine check abort handling
  910. nomce [IA-32] Machine Check Exception
  911. noreplace-paravirt [IA-32,PV_OPS] Don't patch paravirt_ops
  912. noreplace-smp [IA-32,SMP] Don't replace SMP instructions
  913. with UP alternatives
  914. noresidual [PPC] Don't use residual data on PReP machines.
  915. noresume [SWSUSP] Disables resume and restores original swap
  916. space.
  917. no-scroll [VGA] Disables scrollback.
  918. This is required for the Braillex ib80-piezo Braille
  919. reader made by F.H. Papenmeier (Germany).
  920. nosbagart [IA-64]
  921. nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
  922. nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
  923. nosync [HW,M68K] Disables sync negotiation for all devices.
  924. notsc [BUGS=IA-32] Disable Time Stamp Counter
  925. nousb [USB] Disable the USB subsystem
  926. nowb [ARM]
  927. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
  928. opl3= [HW,OSS]
  929. Format: <io>
  930. opl3sa2= [HW,OSS] Format:
  931. <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
  932. oprofile.timer= [HW]
  933. Use timer interrupt instead of performance counters
  934. optcd= [HW,CD]
  935. Format: <io>
  936. osst= [HW,SCSI] SCSI Tape Driver
  937. Format: <buffer_size>,<write_threshold>
  938. See also Documentation/scsi/st.txt.
  939. panic= [KNL] Kernel behaviour on panic
  940. Format: <timeout>
  941. parkbd.port= [HW] Parallel port number the keyboard adapter is
  942. connected to, default is 0.
  943. Format: <parport#>
  944. parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
  945. 0 for XT, 1 for AT (default is AT).
  946. Format: <mode>
  947. parport= [HW,PPT] Specify parallel ports. 0 disables.
  948. Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
  949. Use 'auto' to force the driver to use any
  950. IRQ/DMA settings detected (the default is to
  951. ignore detected IRQ/DMA settings because of
  952. possible conflicts). You can specify the base
  953. address, IRQ, and DMA settings; IRQ and DMA
  954. should be numbers, or 'auto' (for using detected
  955. settings on that particular port), or 'nofifo'
  956. (to avoid using a FIFO even if it is detected).
  957. Parallel ports are assigned in the order they
  958. are specified on the command line, starting
  959. with parport0.
  960. parport_init_mode= [HW,PPT]
  961. Configure VIA parallel port to operate in
  962. a specific mode. This is necessary on Pegasos
  963. computer where firmware has no options for setting
  964. up parallel port mode and sets it to spp.
  965. Currently this function knows 686a and 8231 chips.
  966. Format: [spp|ps2|epp|ecp|ecpepp]
  967. pas2= [HW,OSS] Format:
  968. <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
  969. pas16= [HW,SCSI]
  970. See header of drivers/scsi/pas16.c.
  971. pause_on_oops=
  972. Halt all CPUs after the first oops has been printed for
  973. the specified number of seconds. This is to be used if
  974. your oopses keep scrolling off the screen.
  975. pcbit= [HW,ISDN]
  976. pcd. [PARIDE]
  977. See header of drivers/block/paride/pcd.c.
  978. See also Documentation/paride.txt.
  979. pci=option[,option...] [PCI] various PCI subsystem options:
  980. off [IA-32] don't probe for the PCI bus
  981. bios [IA-32] force use of PCI BIOS, don't access
  982. the hardware directly. Use this if your machine
  983. has a non-standard PCI host bridge.
  984. nobios [IA-32] disallow use of PCI BIOS, only direct
  985. hardware access methods are allowed. Use this
  986. if you experience crashes upon bootup and you
  987. suspect they are caused by the BIOS.
  988. conf1 [IA-32] Force use of PCI Configuration
  989. Mechanism 1.
  990. conf2 [IA-32] Force use of PCI Configuration
  991. Mechanism 2.
  992. nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
  993. Configuration
  994. nomsi [MSI] If the PCI_MSI kernel config parameter is
  995. enabled, this kernel boot option can be used to
  996. disable the use of MSI interrupts system-wide.
  997. nosort [IA-32] Don't sort PCI devices according to
  998. order given by the PCI BIOS. This sorting is
  999. done to get a device order compatible with
  1000. older kernels.
  1001. biosirq [IA-32] Use PCI BIOS calls to get the interrupt
  1002. routing table. These calls are known to be buggy
  1003. on several machines and they hang the machine
  1004. when used, but on other computers it's the only
  1005. way to get the interrupt routing table. Try
  1006. this option if the kernel is unable to allocate
  1007. IRQs or discover secondary PCI buses on your
  1008. motherboard.
  1009. rom [IA-32] Assign address space to expansion ROMs.
  1010. Use with caution as certain devices share
  1011. address decoders between ROMs and other
  1012. resources.
  1013. irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
  1014. assigned automatically to PCI devices. You can
  1015. make the kernel exclude IRQs of your ISA cards
  1016. this way.
  1017. pirqaddr=0xAAAAA [IA-32] Specify the physical address
  1018. of the PIRQ table (normally generated
  1019. by the BIOS) if it is outside the
  1020. F0000h-100000h range.
  1021. lastbus=N [IA-32] Scan all buses thru bus #N. Can be
  1022. useful if the kernel is unable to find your
  1023. secondary buses and you want to tell it
  1024. explicitly which ones they are.
  1025. assign-busses [IA-32] Always assign all PCI bus
  1026. numbers ourselves, overriding
  1027. whatever the firmware may have done.
  1028. usepirqmask [IA-32] Honor the possible IRQ mask stored
  1029. in the BIOS $PIR table. This is needed on
  1030. some systems with broken BIOSes, notably
  1031. some HP Pavilion N5400 and Omnibook XE3
  1032. notebooks. This will have no effect if ACPI
  1033. IRQ routing is enabled.
  1034. noacpi [IA-32] Do not use ACPI for IRQ routing
  1035. or for PCI scanning.
  1036. routeirq Do IRQ routing for all PCI devices.
  1037. This is normally done in pci_enable_device(),
  1038. so this option is a temporary workaround
  1039. for broken drivers that don't call it.
  1040. firmware [ARM] Do not re-enumerate the bus but instead
  1041. just use the configuration from the
  1042. bootloader. This is currently used on
  1043. IXP2000 systems where the bus has to be
  1044. configured a certain way for adjunct CPUs.
  1045. noearly [X86] Don't do any early type 1 scanning.
  1046. This might help on some broken boards which
  1047. machine check when some devices' config space
  1048. is read. But various workarounds are disabled
  1049. and some IOMMU drivers will not work.
  1050. bfsort Sort PCI devices into breadth-first order.
  1051. This sorting is done to get a device
  1052. order compatible with older (<= 2.4) kernels.
  1053. nobfsort Don't sort PCI devices into breadth-first order.
  1054. cbiosize=nn[KMG] The fixed amount of bus space which is
  1055. reserved for the CardBus bridge's IO window.
  1056. The default value is 256 bytes.
  1057. cbmemsize=nn[KMG] The fixed amount of bus space which is
  1058. reserved for the CardBus bridge's memory
  1059. window. The default value is 64 megabytes.
  1060. pcmv= [HW,PCMCIA] BadgePAD 4
  1061. pd. [PARIDE]
  1062. See Documentation/paride.txt.
  1063. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
  1064. boot time.
  1065. Format: { 0 | 1 }
  1066. See arch/parisc/kernel/pdc_chassis.c
  1067. pf. [PARIDE]
  1068. See Documentation/paride.txt.
  1069. pg. [PARIDE]
  1070. See Documentation/paride.txt.
  1071. pirq= [SMP,APIC] Manual mp-table setup
  1072. See Documentation/i386/IO-APIC.txt.
  1073. plip= [PPT,NET] Parallel port network link
  1074. Format: { parport<nr> | timid | 0 }
  1075. See also Documentation/parport.txt.
  1076. pnpacpi= [ACPI]
  1077. { off }
  1078. pnpbios= [ISAPNP]
  1079. { on | off | curr | res | no-curr | no-res }
  1080. pnp_reserve_irq=
  1081. [ISAPNP] Exclude IRQs for the autoconfiguration
  1082. pnp_reserve_dma=
  1083. [ISAPNP] Exclude DMAs for the autoconfiguration
  1084. pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
  1085. Ranges are in pairs (I/O port base and size).
  1086. pnp_reserve_mem=
  1087. [ISAPNP] Exclude memory regions for the
  1088. autoconfiguration.
  1089. Ranges are in pairs (memory base and size).
  1090. profile= [KNL] Enable kernel profiling via /proc/profile
  1091. Format: [schedule,]<number>
  1092. Param: "schedule" - profile schedule points.
  1093. Param: <number> - step/bucket size as a power of 2 for
  1094. statistical time based profiling.
  1095. Param: "sleep" - profile D-state sleeping (millisecs)
  1096. processor.max_cstate= [HW,ACPI]
  1097. Limit processor to maximum C-state
  1098. max_cstate=9 overrides any DMI blacklist limit.
  1099. processor.nocst [HW,ACPI]
  1100. Ignore the _CST method to determine C-states,
  1101. instead using the legacy FADT method
  1102. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
  1103. before loading.
  1104. See Documentation/ramdisk.txt.
  1105. psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
  1106. probe for; one of (bare|imps|exps|lifebook|any).
  1107. psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
  1108. per second.
  1109. psmouse.resetafter= [HW,MOUSE]
  1110. Try to reset the device after so many bad packets
  1111. (0 = never).
  1112. psmouse.resolution=
  1113. [HW,MOUSE] Set desired mouse resolution, in dpi.
  1114. psmouse.smartscroll=
  1115. [HW,MOUSE] Controls Logitech smartscroll autorepeat.
  1116. 0 = disabled, 1 = enabled (default).
  1117. pss= [HW,OSS] Personal Sound System (ECHO ESC614)
  1118. Format:
  1119. <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
  1120. pt. [PARIDE]
  1121. See Documentation/paride.txt.
  1122. quiet [KNL] Disable most log messages
  1123. r128= [HW,DRM]
  1124. raid= [HW,RAID]
  1125. See Documentation/md.txt.
  1126. ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
  1127. See Documentation/ramdisk.txt.
  1128. ramdisk_blocksize= [RAM]
  1129. See Documentation/ramdisk.txt.
  1130. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
  1131. New name for the ramdisk parameter.
  1132. See Documentation/ramdisk.txt.
  1133. rcu.blimit= [KNL,BOOT] Set maximum number of finished
  1134. RCU callbacks to process in one batch.
  1135. rcu.qhimark= [KNL,BOOT] Set threshold of queued
  1136. RCU callbacks over which batch limiting is disabled.
  1137. rcu.qlowmark= [KNL,BOOT] Set threshold of queued
  1138. RCU callbacks below which batch limiting is re-enabled.
  1139. rdinit= [KNL]
  1140. Format: <full_path>
  1141. Run specified binary instead of /init from the ramdisk,
  1142. used for early userspace startup. See initrd.
  1143. reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
  1144. Format: <reboot_mode>[,<reboot_mode2>[,...]]
  1145. See arch/*/kernel/reboot.c or arch/*/kernel/process.c
  1146. reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
  1147. reservetop= [IA-32]
  1148. Format: nn[KMG]
  1149. Reserves a hole at the top of the kernel virtual
  1150. address space.
  1151. reset_devices [KNL] Force drivers to reset the underlying device
  1152. during initialization.
  1153. resume= [SWSUSP]
  1154. Specify the partition device for software suspend
  1155. resume_offset= [SWSUSP]
  1156. Specify the offset from the beginning of the partition
  1157. given by "resume=" at which the swap header is located,
  1158. in <PAGE_SIZE> units (needed only for swap files).
  1159. See Documentation/power/swsusp-and-swap-files.txt
  1160. retain_initrd [RAM] Keep initrd memory after extraction
  1161. rhash_entries= [KNL,NET]
  1162. Set number of hash buckets for route cache
  1163. riscom8= [HW,SERIAL]
  1164. Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
  1165. ro [KNL] Mount root device read-only on boot
  1166. root= [KNL] Root filesystem
  1167. rootdelay= [KNL] Delay (in seconds) to pause before attempting to
  1168. mount the root filesystem
  1169. rootflags= [KNL] Set root filesystem mount option string
  1170. rootfstype= [KNL] Set root filesystem type
  1171. rw [KNL] Mount root device read-write on boot
  1172. S [KNL] Run init in single mode
  1173. sa1100ir [NET]
  1174. See drivers/net/irda/sa1100_ir.c.
  1175. sb= [HW,OSS]
  1176. Format: <io>,<irq>,<dma>,<dma2>
  1177. sbni= [NET] Granch SBNI12 leased line adapter
  1178. sbpcd= [HW,CD] Soundblaster CD adapter
  1179. Format: <io>,<type>
  1180. See a comment before function sbpcd_setup() in
  1181. drivers/cdrom/sbpcd.c.
  1182. sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
  1183. Format: <io>[,<timeout>[,<isapnp>]]
  1184. scsi_debug_*= [SCSI]
  1185. See drivers/scsi/scsi_debug.c.
  1186. scsi_default_dev_flags=
  1187. [SCSI] SCSI default device flags
  1188. Format: <integer>
  1189. scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
  1190. Format: <vendor>:<model>:<flags>
  1191. (flags are integer value)
  1192. scsi_logging= [SCSI]
  1193. scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
  1194. discovered. async scans them in kernel threads,
  1195. allowing boot to proceed. none ignores them, expecting
  1196. user space to do the scan.
  1197. selinux [SELINUX] Disable or enable SELinux at boot time.
  1198. Format: { "0" | "1" }
  1199. See security/selinux/Kconfig help text.
  1200. 0 -- disable.
  1201. 1 -- enable.
  1202. Default value is set via kernel config option.
  1203. If enabled at boot time, /selinux/disable can be used
  1204. later to disable prior to initial policy load.
  1205. selinux_compat_net =
  1206. [SELINUX] Set initial selinux_compat_net flag value.
  1207. Format: { "0" | "1" }
  1208. 0 -- use new secmark-based packet controls
  1209. 1 -- use legacy packet controls
  1210. Default value is 0 (preferred).
  1211. Value can be changed at runtime via
  1212. /selinux/compat_net.
  1213. serialnumber [BUGS=IA-32]
  1214. sg_def_reserved_size= [SCSI]
  1215. shapers= [NET]
  1216. Maximal number of shapers.
  1217. sim710= [SCSI,HW]
  1218. See header of drivers/scsi/sim710.c.
  1219. simeth= [IA-64]
  1220. simscsi=
  1221. sjcd= [HW,CD]
  1222. Format: <io>,<irq>,<dma>
  1223. See header of drivers/cdrom/sjcd.c.
  1224. slram= [HW,MTD]
  1225. smart2= [HW]
  1226. Format: <io1>[,<io2>[,...,<io8>]]
  1227. smp-alt-once [IA-32,SMP] On a hotplug CPU system, only
  1228. attempt to substitute SMP alternatives once at boot.
  1229. smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
  1230. smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
  1231. smsc-ircc2.ircc_sir= [HW] SIR base I/O port
  1232. smsc-ircc2.ircc_fir= [HW] FIR base I/O port
  1233. smsc-ircc2.ircc_irq= [HW] IRQ line
  1234. smsc-ircc2.ircc_dma= [HW] DMA channel
  1235. smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
  1236. 0: Toshiba Satellite 1800 (GP data pin select)
  1237. 1: Fast pin select (default)
  1238. 2: ATC IRMode
  1239. snd-ad1816a= [HW,ALSA]
  1240. snd-ad1848= [HW,ALSA]
  1241. snd-ali5451= [HW,ALSA]
  1242. snd-als100= [HW,ALSA]
  1243. snd-als4000= [HW,ALSA]
  1244. snd-azt2320= [HW,ALSA]
  1245. snd-cmi8330= [HW,ALSA]
  1246. snd-cmipci= [HW,ALSA]
  1247. snd-cs4231= [HW,ALSA]
  1248. snd-cs4232= [HW,ALSA]
  1249. snd-cs4236= [HW,ALSA]
  1250. snd-cs4281= [HW,ALSA]
  1251. snd-cs46xx= [HW,ALSA]
  1252. snd-dt019x= [HW,ALSA]
  1253. snd-dummy= [HW,ALSA]
  1254. snd-emu10k1= [HW,ALSA]
  1255. snd-ens1370= [HW,ALSA]
  1256. snd-ens1371= [HW,ALSA]
  1257. snd-es968= [HW,ALSA]
  1258. snd-es1688= [HW,ALSA]
  1259. snd-es18xx= [HW,ALSA]
  1260. snd-es1938= [HW,ALSA]
  1261. snd-es1968= [HW,ALSA]
  1262. snd-fm801= [HW,ALSA]
  1263. snd-gusclassic= [HW,ALSA]
  1264. snd-gusextreme= [HW,ALSA]
  1265. snd-gusmax= [HW,ALSA]
  1266. snd-hdsp= [HW,ALSA]
  1267. snd-ice1712= [HW,ALSA]
  1268. snd-intel8x0= [HW,ALSA]
  1269. snd-interwave= [HW,ALSA]
  1270. snd-interwave-stb=
  1271. [HW,ALSA]
  1272. snd-korg1212= [HW,ALSA]
  1273. snd-maestro3= [HW,ALSA]
  1274. snd-mpu401= [HW,ALSA]
  1275. snd-mtpav= [HW,ALSA]
  1276. snd-nm256= [HW,ALSA]
  1277. snd-opl3sa2= [HW,ALSA]
  1278. snd-opti92x-ad1848=
  1279. [HW,ALSA]
  1280. snd-opti92x-cs4231=
  1281. [HW,ALSA]
  1282. snd-opti93x= [HW,ALSA]
  1283. snd-pmac= [HW,ALSA]
  1284. snd-rme32= [HW,ALSA]
  1285. snd-rme96= [HW,ALSA]
  1286. snd-rme9652= [HW,ALSA]
  1287. snd-sb8= [HW,ALSA]
  1288. snd-sb16= [HW,ALSA]
  1289. snd-sbawe= [HW,ALSA]
  1290. snd-serial= [HW,ALSA]
  1291. snd-sgalaxy= [HW,ALSA]
  1292. snd-sonicvibes= [HW,ALSA]
  1293. snd-sun-amd7930=
  1294. [HW,ALSA]
  1295. snd-sun-cs4231= [HW,ALSA]
  1296. snd-trident= [HW,ALSA]
  1297. snd-usb-audio= [HW,ALSA,USB]
  1298. snd-via82xx= [HW,ALSA]
  1299. snd-virmidi= [HW,ALSA]
  1300. snd-wavefront= [HW,ALSA]
  1301. snd-ymfpci= [HW,ALSA]
  1302. sonycd535= [HW,CD]
  1303. Format: <io>[,<irq>]
  1304. sonypi.*= [HW] Sony Programmable I/O Control Device driver
  1305. See Documentation/sonypi.txt
  1306. specialix= [HW,SERIAL] Specialix multi-serial port adapter
  1307. See Documentation/specialix.txt.
  1308. spia_io_base= [HW,MTD]
  1309. spia_fio_base=
  1310. spia_pedr=
  1311. spia_peddr=
  1312. sscape= [HW,OSS]
  1313. Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
  1314. st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
  1315. See Documentation/scsi/st.txt.
  1316. st0x= [HW,SCSI]
  1317. See header of drivers/scsi/seagate.c.
  1318. sti= [PARISC,HW]
  1319. Format: <num>
  1320. Set the STI (builtin display/keyboard on the HP-PARISC
  1321. machines) console (graphic card) which should be used
  1322. as the initial boot-console.
  1323. See also comment in drivers/video/console/sticore.c.
  1324. sti_font= [HW]
  1325. See comment in drivers/video/console/sticore.c.
  1326. stifb= [HW]
  1327. Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
  1328. sunrpc.pool_mode=
  1329. [NFS]
  1330. Control how the NFS server code allocates CPUs to
  1331. service thread pools. Depending on how many NICs
  1332. you have and where their interrupts are bound, this
  1333. option will affect which CPUs will do NFS serving.
  1334. Note: this parameter cannot be changed while the
  1335. NFS server is running.
  1336. auto the server chooses an appropriate mode
  1337. automatically using heuristics
  1338. global a single global pool contains all CPUs
  1339. percpu one pool for each CPU
  1340. pernode one pool for each NUMA node (equivalent
  1341. to global on non-NUMA machines)
  1342. swiotlb= [IA-64] Number of I/O TLB slabs
  1343. switches= [HW,M68k]
  1344. sym53c416= [HW,SCSI]
  1345. See header of drivers/scsi/sym53c416.c.
  1346. sysrq_always_enabled
  1347. [KNL]
  1348. Ignore sysrq setting - this boot parameter will
  1349. neutralize any effect of /proc/sys/kernel/sysrq.
  1350. Useful for debugging.
  1351. t128= [HW,SCSI]
  1352. See header of drivers/scsi/t128.c.
  1353. tdfx= [HW,DRM]
  1354. thash_entries= [KNL,NET]
  1355. Set number of hash buckets for TCP connection
  1356. time Show timing data prefixed to each printk message line
  1357. clocksource= [GENERIC_TIME] Override the default clocksource
  1358. Override the default clocksource and use the clocksource
  1359. with the name specified.
  1360. tipar.timeout= [HW,PPT]
  1361. Set communications timeout in tenths of a second
  1362. (default 15).
  1363. tipar.delay= [HW,PPT]
  1364. Set inter-bit delay in microseconds (default 10).
  1365. tmc8xx= [HW,SCSI]
  1366. See header of drivers/scsi/seagate.c.
  1367. tmscsim= [HW,SCSI]
  1368. See comment before function dc390_setup() in
  1369. drivers/scsi/tmscsim.c.
  1370. tp720= [HW,PS2]
  1371. trix= [HW,OSS] MediaTrix AudioTrix Pro
  1372. Format:
  1373. <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
  1374. tsdev.xres= [TS] Horizontal screen resolution.
  1375. tsdev.yres= [TS] Vertical screen resolution.
  1376. turbografx.map[2|3]= [HW,JOY]
  1377. TurboGraFX parallel port interface
  1378. Format:
  1379. <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
  1380. See also Documentation/input/joystick-parport.txt
  1381. u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
  1382. See header of drivers/scsi/u14-34f.c.
  1383. uart401= [HW,OSS]
  1384. Format: <io>,<irq>
  1385. uart6850= [HW,OSS]
  1386. Format: <io>,<irq>
  1387. uhci-hcd.ignore_oc=
  1388. [USB] Ignore overcurrent events (default N).
  1389. Some badly-designed motherboards generate lots of
  1390. bogus events, for ports that aren't wired to
  1391. anything. Set this parameter to avoid log spamming.
  1392. Note that genuine overcurrent events won't be
  1393. reported either.
  1394. usbcore.autosuspend=
  1395. [USB] The autosuspend time delay (in seconds) used
  1396. for newly-detected USB devices (default 2). This
  1397. is the time required before an idle device will be
  1398. autosuspended. Devices for which the delay is set
  1399. to a negative value won't be autosuspended at all.
  1400. usbhid.mousepoll=
  1401. [USBHID] The interval which mice are to be polled at.
  1402. vdso= [IA-32,SH]
  1403. vdso=2: enable compat VDSO (default with COMPAT_VDSO)
  1404. vdso=1: enable VDSO (default)
  1405. vdso=0: disable VDSO mapping
  1406. video= [FB] Frame buffer configuration
  1407. See Documentation/fb/modedb.txt.
  1408. vga= [BOOT,IA-32] Select a particular video mode
  1409. See Documentation/i386/boot.txt and
  1410. Documentation/svga.txt.
  1411. Use vga=ask for menu.
  1412. This is actually a boot loader parameter; the value is
  1413. passed to the kernel using a special protocol.
  1414. vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
  1415. size of <nn>. This can be used to increase the
  1416. minimum size (128MB on x86). It can also be used to
  1417. decrease the size and leave more room for directly
  1418. mapped kernel RAM.
  1419. vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
  1420. Format: <command>
  1421. vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
  1422. Format: <command>
  1423. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
  1424. Format: <command>
  1425. waveartist= [HW,OSS]
  1426. Format: <io>,<irq>,<dma>,<dma2>
  1427. wd33c93= [HW,SCSI]
  1428. See header of drivers/scsi/wd33c93.c.
  1429. wd7000= [HW,SCSI]
  1430. See header of drivers/scsi/wd7000.c.
  1431. wdt= [WDT] Watchdog
  1432. See Documentation/watchdog/watchdog.txt.
  1433. xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
  1434. xd_geo= See header of drivers/block/xd.c.
  1435. xirc2ps_cs= [NET,PCMCIA]
  1436. Format:
  1437. <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
  1438. norandmaps Don't use address space randomization
  1439. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
  1440. unwind_debug=N N > 0 will enable dwarf2 unwinder debugging
  1441. This is useful to get more information why
  1442. you got a "dwarf2 unwinder stuck"
  1443. ______________________________________________________________________
  1444. TODO:
  1445. Add documentation for ALSA options.
  1446. Add more DRM drivers.