Commit | Line | Data |
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e53dd083 MCC |
1 | Kernel Parameters |
2 | ~~~~~~~~~~~~~~~~~ | |
1da177e4 LT |
3 | |
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. | |
8 | ||
9 | Module parameters for loadable modules are specified only as the | |
10 | parameter name with optional '=' and value as appropriate, such as: | |
11 | ||
12 | modprobe usbcore blinkenlights=1 | |
13 | ||
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: | |
17 | ||
18 | usbcore.blinkenlights=1 | |
19 | ||
a901ebb9 SR |
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}". | |
26 | ||
6585fa8a SR |
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: | |
1da177e4 LT |
31 | |
32 | ACPI ACPI support is enabled. | |
c99c108a | 33 | AGP AGP (Accelerated Graphics Port) is enabled. |
1da177e4 LT |
34 | ALSA ALSA sound support is enabled. |
35 | APIC APIC support is enabled. | |
36 | APM Advanced Power Management support is enabled. | |
e7ba176b | 37 | AVR32 AVR32 architecture is enabled. |
1da177e4 | 38 | AX25 Appropriate AX.25 support is enabled. |
0ae53640 | 39 | BLACKFIN Blackfin architecture is enabled. |
a9913044 | 40 | DRM Direct Rendering Management support is enabled. |
1da177e4 LT |
41 | EDD BIOS Enhanced Disk Drive Services (EDD) is enabled |
42 | EFI EFI Partitioning (GPT) is enabled | |
43 | EIDE EIDE/ATAPI support is enabled. | |
44 | FB The frame buffer device is enabled. | |
45 | HW Appropriate hardware is enabled. | |
1da177e4 LT |
46 | IA-64 IA-64 architecture is enabled. |
47 | IOSCHED More than one I/O scheduler is enabled. | |
41e2e8be | 48 | IP_PNP IP DHCP, BOOTP, or RARP is enabled. |
1da177e4 LT |
49 | ISAPNP ISA PnP code is enabled. |
50 | ISDN Appropriate ISDN support is enabled. | |
51 | JOY Appropriate joystick support is enabled. | |
11ef697b | 52 | LIBATA Libata driver is enabled |
1da177e4 LT |
53 | LP Printer support is enabled. |
54 | LOOP Loopback device support is enabled. | |
55 | M68k M68k architecture is enabled. | |
56 | These options have more detailed description inside of | |
57 | Documentation/m68k/kernel-options.txt. | |
58 | MCA MCA bus support is enabled. | |
59 | MDA MDA console support is enabled. | |
60 | MOUSE Appropriate mouse support is enabled. | |
309e57df | 61 | MSI Message Signaled Interrupts (PCI). |
c8facbb6 | 62 | MTD MTD (Memory Technology Device) support is enabled. |
1da177e4 LT |
63 | NET Appropriate network support is enabled. |
64 | NUMA NUMA support is enabled. | |
734efb46 | 65 | GENERIC_TIME The generic timeofday code is enabled. |
1da177e4 LT |
66 | NFS Appropriate NFS support is enabled. |
67 | OSS OSS sound support is enabled. | |
c8facbb6 RD |
68 | PV_OPS A paravirtualized kernel is enabled. |
69 | PARIDE The ParIDE (parallel port IDE) subsystem is enabled. | |
1da177e4 LT |
70 | PARISC The PA-RISC architecture is enabled. |
71 | PCI PCI bus support is enabled. | |
7f785763 | 72 | PCIE PCI Express support is enabled. |
1da177e4 LT |
73 | PCMCIA The PCMCIA subsystem is enabled. |
74 | PNP Plug & Play support is enabled. | |
75 | PPC PowerPC architecture is enabled. | |
76 | PPT Parallel port support is enabled. | |
77 | PS2 Appropriate PS/2 support is enabled. | |
78 | RAM RAM disk support is enabled. | |
20510f2f | 79 | ROOTPLUG The example Root Plug LSM is enabled. |
1da177e4 LT |
80 | S390 S390 architecture is enabled. |
81 | SCSI Appropriate SCSI support is enabled. | |
82 | A lot of drivers has their options described inside of | |
83 | Documentation/scsi/. | |
20510f2f | 84 | SECURITY Different security models are enabled. |
1da177e4 LT |
85 | SELINUX SELinux support is enabled. |
86 | SERIAL Serial support is enabled. | |
e523d93c | 87 | SH SuperH architecture is enabled. |
1da177e4 LT |
88 | SMP The kernel is an SMP kernel. |
89 | SPARC Sparc architecture is enabled. | |
77437fd4 DB |
90 | SWSUSP Software suspend (hibernation) is enabled. |
91 | SUSPEND System suspend states are enabled. | |
1da177e4 LT |
92 | TS Appropriate touchscreen support is enabled. |
93 | USB USB support is enabled. | |
94 | USBHID USB Human Interface Device support is enabled. | |
95 | V4L Video For Linux support is enabled. | |
96 | VGA The VGA console has been enabled. | |
97 | VT Virtual terminal support is enabled. | |
98 | WDT Watchdog support is enabled. | |
99 | XT IBM PC/XT MFM hard disk support is enabled. | |
cd4f0ef7 | 100 | X86-32 X86-32, aka i386 architecture is enabled. |
1da177e4 LT |
101 | X86-64 X86-64 architecture is enabled. |
102 | More X86-64 boot options can be found in | |
103 | Documentation/x86_64/boot-options.txt . | |
104 | ||
105 | In addition, the following text indicates that the option: | |
106 | ||
107 | BUGS= Relates to possible processor bugs on the said processor. | |
108 | KNL Is a kernel start-up parameter. | |
109 | BOOT Is a boot loader parameter. | |
110 | ||
111 | Parameters denoted with BOOT are actually interpreted by the boot | |
112 | loader, and have no meaning to the kernel directly. | |
113 | Do not modify the syntax of boot loader parameters without extreme | |
114 | need or coordination with <Documentation/i386/boot.txt>. | |
115 | ||
5558870b KW |
116 | There are also arch-specific kernel-parameters not documented here. |
117 | See for example <Documentation/x86_64/boot-options.txt>. | |
118 | ||
1da177e4 LT |
119 | Note that ALL kernel parameters listed below are CASE SENSITIVE, and that |
120 | a trailing = on the name of any parameter states that that parameter will | |
121 | be entered as an environment variable, whereas its absence indicates that | |
122 | it will appear as a kernel argument readable via /proc/cmdline by programs | |
123 | running once the system is up. | |
124 | ||
9c4751fd | 125 | The number of kernel parameters is not limited, but the length of the |
126 | complete command line (parameters including spaces etc.) is limited to | |
127 | a fixed number of characters. This limit depends on the architecture | |
128 | and is between 256 and 4096 characters. It is defined in the file | |
129 | ./include/asm/setup.h as COMMAND_LINE_SIZE. | |
130 | ||
131 | ||
03d926f8 BW |
132 | acpi= [HW,ACPI,X86-64,i386] |
133 | Advanced Configuration and Power Interface | |
a9913044 | 134 | Format: { force | off | ht | strict | noirq } |
1da177e4 LT |
135 | force -- enable ACPI if default was off |
136 | off -- disable ACPI if default was on | |
137 | noirq -- do not use ACPI for IRQ routing | |
138 | ht -- run only enough ACPI to enable Hyper Threading | |
a9913044 | 139 | strict -- Be less tolerant of platforms that are not |
1da177e4 LT |
140 | strictly ACPI specification compliant. |
141 | ||
53471121 | 142 | See also Documentation/power/pm.txt, pci=noacpi |
1da177e4 | 143 | |
a1fdcc0d LB |
144 | acpi_apic_instance= [ACPI, IOAPIC] |
145 | Format: <int> | |
146 | 2: use 2nd APIC table, if available | |
147 | 1,0: use 1st APIC table | |
4e381a4f | 148 | default: 0 |
a1fdcc0d | 149 | |
1da177e4 | 150 | acpi_sleep= [HW,ACPI] Sleep options |
bdfe6b7c | 151 | Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering } |
23b168d4 PM |
152 | See Documentation/power/video.txt for s3_bios and s3_mode. |
153 | s3_beep is for debugging; it makes the PC's speaker beep | |
154 | as soon as the kernel's real-mode entry point is called. | |
bdfe6b7c SL |
155 | s4_nohwsig prevents ACPI hardware signature from being |
156 | used during resume from hibernation. | |
d8f3de0d RW |
157 | old_ordering causes the ACPI 1.0 ordering of the _PTS |
158 | control method, wrt putting devices into low power | |
159 | states, to be enforced (the ACPI 2.0 ordering of _PTS is | |
160 | used by default). | |
a9913044 | 161 | |
1da177e4 | 162 | acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode |
a9913044 | 163 | Format: { level | edge | high | low } |
1da177e4 | 164 | |
a9913044 RD |
165 | acpi_irq_balance [HW,ACPI] |
166 | ACPI will balance active IRQs | |
167 | default in APIC mode | |
1da177e4 | 168 | |
a9913044 RD |
169 | acpi_irq_nobalance [HW,ACPI] |
170 | ACPI will not move active IRQs (default) | |
171 | default in PIC mode | |
1da177e4 | 172 | |
a9913044 RD |
173 | acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for |
174 | use by PCI | |
1da177e4 LT |
175 | Format: <irq>,<irq>... |
176 | ||
a9913044 | 177 | acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA |
1da177e4 LT |
178 | Format: <irq>,<irq>... |
179 | ||
67effe8f LB |
180 | acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT |
181 | ||
a1f9e65e LB |
182 | acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS |
183 | Format: To spoof as Windows 98: ="Microsoft Windows" | |
184 | ||
ae00d812 LB |
185 | acpi_osi= [HW,ACPI] Modify list of supported OS interface strings |
186 | acpi_osi="string1" # add string1 -- only one string | |
187 | acpi_osi="!string2" # remove built-in string2 | |
188 | acpi_osi= # disable all strings | |
1da177e4 LT |
189 | |
190 | acpi_serialize [HW,ACPI] force serialization of AML methods | |
191 | ||
192 | acpi_skip_timer_override [HW,ACPI] | |
193 | Recognize and ignore IRQ0/pin2 Interrupt Override. | |
194 | For broken nForce2 BIOS resulting in XT-PIC timer. | |
fa18f477 AK |
195 | acpi_use_timer_override [HW,ACPI} |
196 | Use timer override. For some broken Nvidia NF5 boards | |
197 | that require a timer override, but don't have | |
198 | HPET | |
1da177e4 | 199 | |
f989106c | 200 | acpi.debug_layer= [HW,ACPI] |
1da177e4 | 201 | Format: <int> |
a9913044 | 202 | Each bit of the <int> indicates an ACPI debug layer, |
1da177e4 LT |
203 | 1: enable, 0: disable. It is useful for boot time |
204 | debugging. After system has booted up, it can be set | |
f989106c ZR |
205 | via /sys/module/acpi/parameters/debug_layer. |
206 | CONFIG_ACPI_DEBUG must be enabled for this to produce any output. | |
207 | Available bits (add the numbers together) to enable debug output | |
208 | for specific parts of the ACPI subsystem: | |
209 | 0x01 utilities 0x02 hardware 0x04 events 0x08 tables | |
210 | 0x10 namespace 0x20 parser 0x40 dispatcher | |
211 | 0x80 executer 0x100 resources 0x200 acpica debugger | |
212 | 0x400 os services 0x800 acpica disassembler. | |
213 | The number can be in decimal or prefixed with 0x in hex. | |
214 | Warning: Many of these options can produce a lot of | |
215 | output and make your system unusable. Be very careful. | |
216 | ||
217 | acpi.debug_level= [HW,ACPI] | |
1da177e4 | 218 | Format: <int> |
a9913044 | 219 | Each bit of the <int> indicates an ACPI debug level, |
1da177e4 LT |
220 | 1: enable, 0: disable. It is useful for boot time |
221 | debugging. After system has booted up, it can be set | |
f989106c ZR |
222 | via /sys/module/acpi/parameters/debug_level. |
223 | CONFIG_ACPI_DEBUG must be enabled for this to produce any output. | |
224 | Available bits (add the numbers together) to enable different | |
225 | debug output levels of the ACPI subsystem: | |
226 | 0x01 error 0x02 warn 0x04 init 0x08 debug object | |
227 | 0x10 info 0x20 init names 0x40 parse 0x80 load | |
228 | 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region | |
229 | 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects | |
230 | 0x10000 resources 0x20000 user requests 0x40000 package. | |
231 | The number can be in decimal or prefixed with 0x in hex. | |
232 | Warning: Many of these options can produce a lot of | |
233 | output and make your system unusable. Be very careful. | |
234 | ||
cd4f0ef7 | 235 | acpi_pm_good [X86-32,X86-64] |
5d0cf410 | 236 | Override the pmtimer bug detection: force the kernel |
237 | to assume that this machine's pmtimer latches its value | |
238 | and always returns good values. | |
239 | ||
c99c108a CE |
240 | agp= [AGP] |
241 | { off | try_unsupported } | |
242 | off: disable AGP support | |
243 | try_unsupported: try to drive unsupported chipsets | |
244 | (may crash computer or cause data corruption) | |
245 | ||
66759a01 CE |
246 | enable_timer_pin_1 [i386,x86-64] |
247 | Enable PIN 1 of APIC timer | |
a9913044 RD |
248 | Can be useful to work around chipset bugs |
249 | (in particular on some ATI chipsets). | |
66759a01 CE |
250 | The kernel tries to set a reasonable default. |
251 | ||
252 | disable_timer_pin_1 [i386,x86-64] | |
253 | Disable PIN 1 of APIC timer | |
254 | Can be useful to work around chipset bugs. | |
255 | ||
1da177e4 LT |
256 | ad1848= [HW,OSS] |
257 | Format: <io>,<irq>,<dma>,<dma2>,<type> | |
258 | ||
1da177e4 LT |
259 | advansys= [HW,SCSI] |
260 | See header of drivers/scsi/advansys.c. | |
261 | ||
262 | advwdt= [HW,WDT] Advantech WDT | |
263 | Format: <iostart>,<iostop> | |
264 | ||
265 | aedsp16= [HW,OSS] Audio Excel DSP 16 | |
266 | Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq> | |
267 | See also header of sound/oss/aedsp16.c. | |
a9913044 | 268 | |
1da177e4 LT |
269 | aha152x= [HW,SCSI] |
270 | See Documentation/scsi/aha152x.txt. | |
271 | ||
272 | aha1542= [HW,SCSI] | |
273 | Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]] | |
274 | ||
275 | aic7xxx= [HW,SCSI] | |
276 | See Documentation/scsi/aic7xxx.txt. | |
277 | ||
278 | aic79xx= [HW,SCSI] | |
279 | See Documentation/scsi/aic79xx.txt. | |
280 | ||
54b4cbd2 JR |
281 | amd_iommu= [HW,X86-84] |
282 | Pass parameters to the AMD IOMMU driver in the system. | |
283 | Possible values are: | |
54b4cbd2 JR |
284 | isolate - enable device isolation (each device, as far |
285 | as possible, will get its own protection | |
286 | domain) | |
287 | amd_iommu_size= [HW,X86-64] | |
288 | Define the size of the aperture for the AMD IOMMU | |
289 | driver. Possible values are: | |
290 | '32M', '64M' (default), '128M', '256M', '512M', '1G' | |
291 | ||
1da177e4 LT |
292 | amijoy.map= [HW,JOY] Amiga joystick support |
293 | Map of devices attached to JOY0DAT and JOY1DAT | |
294 | Format: <a>,<b> | |
295 | See also Documentation/kernel/input/joystick.txt | |
296 | ||
297 | analog.map= [HW,JOY] Analog joystick and gamepad support | |
298 | Specifies type or capabilities of an analog joystick | |
299 | connected to one of 16 gameports | |
300 | Format: <type1>,<type2>,..<type16> | |
301 | ||
a9913044 RD |
302 | apc= [HW,SPARC] |
303 | Power management functions (SPARCstation-4/5 + deriv.) | |
1da177e4 LT |
304 | Format: noidle |
305 | Disable APC CPU standby support. SPARCstation-Fox does | |
306 | not play well with APC CPU idle - disable it if you have | |
307 | APC and your system crashes randomly. | |
308 | ||
c8facbb6 RD |
309 | apic= [APIC,i386] Advanced Programmable Interrupt Controller |
310 | Change the output verbosity whilst booting | |
1da177e4 LT |
311 | Format: { quiet (default) | verbose | debug } |
312 | Change the amount of debugging information output | |
313 | when initialising the APIC and IO-APIC components. | |
a9913044 | 314 | |
1da177e4 | 315 | apm= [APM] Advanced Power Management |
71f77055 | 316 | See header of arch/x86/kernel/apm_32.c. |
1da177e4 | 317 | |
1da177e4 LT |
318 | arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards |
319 | Format: <io>,<irq>,<nodeID> | |
320 | ||
321 | ataflop= [HW,M68k] | |
322 | ||
323 | atarimouse= [HW,MOUSE] Atari Mouse | |
324 | ||
325 | atascsi= [HW,SCSI] Atari SCSI | |
326 | ||
327 | atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, | |
328 | EzKey and similar keyboards | |
329 | ||
330 | atkbd.reset= [HW] Reset keyboard during initialization | |
331 | ||
a9913044 RD |
332 | atkbd.set= [HW] Select keyboard code set |
333 | Format: <int> (2 = AT (default), 3 = PS/2) | |
1da177e4 LT |
334 | |
335 | atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar | |
336 | keyboards | |
337 | ||
338 | atkbd.softraw= [HW] Choose between synthetic and real raw mode | |
339 | Format: <bool> (0 = real, 1 = synthetic (default)) | |
a9913044 RD |
340 | |
341 | atkbd.softrepeat= [HW] | |
342 | Use software keyboard repeat | |
1da177e4 LT |
343 | |
344 | autotest [IA64] | |
345 | ||
1da177e4 LT |
346 | baycom_epp= [HW,AX25] |
347 | Format: <io>,<mode> | |
a9913044 | 348 | |
1da177e4 LT |
349 | baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem |
350 | Format: <io>,<mode> | |
351 | See header of drivers/net/hamradio/baycom_par.c. | |
352 | ||
a9913044 RD |
353 | baycom_ser_fdx= [HW,AX25] |
354 | BayCom Serial Port AX.25 Modem (Full Duplex Mode) | |
1da177e4 LT |
355 | Format: <io>,<irq>,<mode>[,<baud>] |
356 | See header of drivers/net/hamradio/baycom_ser_fdx.c. | |
357 | ||
a9913044 RD |
358 | baycom_ser_hdx= [HW,AX25] |
359 | BayCom Serial Port AX.25 Modem (Half Duplex Mode) | |
1da177e4 LT |
360 | Format: <io>,<irq>,<mode> |
361 | See header of drivers/net/hamradio/baycom_ser_hdx.c. | |
362 | ||
bfe8df3d RD |
363 | boot_delay= Milliseconds to delay each printk during boot. |
364 | Values larger than 10 seconds (10000) are changed to | |
365 | no delay (0). | |
366 | Format: integer | |
367 | ||
1da177e4 | 368 | bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) |
a9913044 RD |
369 | bttv.radio= Most important insmod options are available as |
370 | kernel args too. | |
1da177e4 LT |
371 | bttv.pll= See Documentation/video4linux/bttv/Insmod-options |
372 | bttv.tuner= and Documentation/video4linux/bttv/CARDLIST | |
373 | ||
374 | BusLogic= [HW,SCSI] | |
375 | See drivers/scsi/BusLogic.c, comment before function | |
376 | BusLogic_ParseDriverOptions(). | |
377 | ||
378 | c101= [NET] Moxa C101 synchronous serial card | |
379 | ||
cd4f0ef7 | 380 | cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. |
1da177e4 LT |
381 | Sometimes CPU hardware bugs make them report the cache |
382 | size incorrectly. The kernel will attempt work arounds | |
383 | to fix known problems, but for some CPUs it is not | |
384 | possible to determine what the correct size should be. | |
385 | This option provides an override for these situations. | |
386 | ||
076c54c5 AD |
387 | security= [SECURITY] Choose a security module to enable at boot. |
388 | If this boot parameter is not specified, only the first | |
389 | security module asking for security registration will be | |
390 | loaded. An invalid security module name will be treated | |
391 | as if no module has been chosen. | |
392 | ||
20510f2f JM |
393 | capability.disable= |
394 | [SECURITY] Disable capabilities. This would normally | |
395 | be used only if an alternative security model is to be | |
396 | configured. Potentially dangerous and should only be | |
397 | used if you are entirely sure of the consequences. | |
398 | ||
14ff56bb SO |
399 | ccw_timeout_log [S390] |
400 | See Documentation/s390/CommonIO for details. | |
1da177e4 | 401 | |
8bab8dde PM |
402 | cgroup_disable= [KNL] Disable a particular controller |
403 | Format: {name of the controller(s) to disable} | |
404 | {Currently supported controllers - "memory"} | |
405 | ||
1da177e4 LT |
406 | checkreqprot [SELINUX] Set initial checkreqprot flag value. |
407 | Format: { "0" | "1" } | |
408 | See security/selinux/Kconfig help text. | |
a9913044 RD |
409 | 0 -- check protection applied by kernel (includes |
410 | any implied execute protection). | |
1da177e4 LT |
411 | 1 -- check protection requested by application. |
412 | Default value is set via a kernel config option. | |
a9913044 RD |
413 | Value can be changed at runtime via |
414 | /selinux/checkreqprot. | |
415 | ||
661ca0da SO |
416 | cio_ignore= [S390] |
417 | See Documentation/s390/CommonIO for details. | |
418 | ||
cd4f0ef7 | 419 | clock= [BUGS=X86-32, HW] gettimeofday clocksource override. |
734efb46 | 420 | [Deprecated] |
3f6dee9b | 421 | Forces specified clocksource (if available) to be used |
734efb46 | 422 | when calculating gettimeofday(). If specified |
3f6dee9b | 423 | clocksource is not available, it defaults to PIT. |
1da177e4 LT |
424 | Format: { pit | tsc | cyclone | pmtmr } |
425 | ||
3d6ac984 RD |
426 | clocksource= [GENERIC_TIME] Override the default clocksource |
427 | Format: <string> | |
428 | Override the default clocksource and use the clocksource | |
429 | with the name specified. | |
430 | Some clocksource names to choose from, depending on | |
431 | the platform: | |
432 | [all] jiffies (this is the base, fallback clocksource) | |
433 | [ACPI] acpi_pm | |
434 | [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, | |
435 | pxa_timer,timer3,32k_counter,timer0_1 | |
436 | [AVR32] avr32 | |
cd4f0ef7 | 437 | [X86-32] pit,hpet,tsc,vmi-timer; |
3d6ac984 RD |
438 | scx200_hrt on Geode; cyclone on IBM x440 |
439 | [MIPS] MIPS | |
440 | [PARISC] cr16 | |
441 | [S390] tod | |
442 | [SH] SuperH | |
443 | [SPARC64] tick | |
444 | [X86-64] hpet,tsc | |
445 | ||
ac72e788 AK |
446 | clearcpuid=BITNUM [X86] |
447 | Disable CPUID feature X for the kernel. See | |
448 | include/asm-x86/cpufeature.h for the valid bit numbers. | |
449 | Note the Linux specific bits are not necessarily | |
450 | stable over kernel options, but the vendor specific | |
451 | ones should be. | |
452 | Also note that user programs calling CPUID directly | |
453 | or using the feature without checking anything | |
454 | will still see it. This just prevents it from | |
455 | being used by the kernel or shown in /proc/cpuinfo. | |
456 | Also note the kernel might malfunction if you disable | |
457 | some critical bits. | |
458 | ||
a25bd949 AV |
459 | code_bytes [IA32/X86_64] How many bytes of object code to print |
460 | in an oops report. | |
86c41837 CE |
461 | Range: 0 - 8192 |
462 | Default: 64 | |
463 | ||
f9262c12 AK |
464 | disable_8254_timer |
465 | enable_8254_timer | |
466 | [IA32/X86_64] Disable/Enable interrupt 0 timer routing | |
467 | over the 8254 in addition to over the IO-APIC. The | |
468 | kernel tries to set a sensible default. | |
469 | ||
b17530bd TG |
470 | hpet= [X86-32,HPET] option to control HPET usage |
471 | Format: { enable (default) | disable | force } | |
472 | disable: disable HPET and use PIT instead | |
d79a5f80 CC |
473 | force: allow force enabled of undocumented chips (ICH4, |
474 | VIA, nVidia) | |
1da177e4 | 475 | |
1da177e4 | 476 | com20020= [HW,NET] ARCnet - COM20020 chipset |
a9913044 RD |
477 | Format: |
478 | <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] | |
1da177e4 LT |
479 | |
480 | com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) | |
481 | Format: <io>[,<irq>] | |
482 | ||
a9913044 RD |
483 | com90xx= [HW,NET] |
484 | ARCnet - COM90xx chipset (memory-mapped buffers) | |
1da177e4 LT |
485 | Format: <io>[,<irq>[,<memstart>]] |
486 | ||
487 | condev= [HW,S390] console device | |
488 | conmode= | |
a9913044 | 489 | |
1da177e4 LT |
490 | console= [KNL] Output console device and options. |
491 | ||
492 | tty<n> Use the virtual console device <n>. | |
493 | ||
494 | ttyS<n>[,options] | |
f1a1c2dc | 495 | ttyUSB0[,options] |
1da177e4 | 496 | Use the specified serial port. The options are of |
f1a1c2dc RD |
497 | the form "bbbbpnf", where "bbbb" is the baud rate, |
498 | "p" is parity ("n", "o", or "e"), "n" is number of | |
499 | bits, and "f" is flow control ("r" for RTS or | |
500 | omit it). Default is "9600n8". | |
501 | ||
502 | See Documentation/serial-console.txt for more | |
503 | information. See | |
504 | Documentation/networking/netconsole.txt for an | |
505 | alternative. | |
1da177e4 | 506 | |
18a8bd94 YL |
507 | uart[8250],io,<addr>[,options] |
508 | uart[8250],mmio,<addr>[,options] | |
1da177e4 LT |
509 | Start an early, polled-mode console on the 8250/16550 |
510 | UART at the specified I/O port or MMIO address, | |
511 | switching to the matching ttyS device later. The | |
512 | options are the same as for ttyS, above. | |
513 | ||
f7511d5f ST |
514 | If the device connected to the port is not a TTY but a braille |
515 | device, prepend "brl," before the device type, for instance | |
516 | console=brl,ttyS0 | |
517 | For now, only VisioBraille is supported. | |
518 | ||
18a8bd94 YL |
519 | earlycon= [KNL] Output early console device and options. |
520 | uart[8250],io,<addr>[,options] | |
521 | uart[8250],mmio,<addr>[,options] | |
522 | Start an early, polled-mode console on the 8250/16550 | |
523 | UART at the specified I/O port or MMIO address. | |
524 | The options are the same as for ttyS, above. | |
525 | ||
8f4ce8c3 AS |
526 | no_console_suspend |
527 | [HW] Never suspend the console | |
528 | Disable suspending of consoles during suspend and | |
529 | hibernate operations. Once disabled, debugging | |
530 | messages can reach various consoles while the rest | |
531 | of the system is being put to sleep (ie, while | |
532 | debugging driver suspend/resume hooks). This may | |
533 | not work reliably with all consoles, but is known | |
534 | to work with serial and VGA consoles. | |
535 | ||
1da177e4 | 536 | cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver |
a9913044 RD |
537 | Format: |
538 | <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] | |
1da177e4 | 539 | |
dc009d92 EB |
540 | crashkernel=nn[KMG]@ss[KMG] |
541 | [KNL] Reserve a chunk of physical memory to | |
542 | hold a kernel to switch to with kexec on panic. | |
543 | ||
fb391599 BW |
544 | crashkernel=range1:size1[,range2:size2,...][@offset] |
545 | [KNL] Same as above, but depends on the memory | |
546 | in the running system. The syntax of range is | |
547 | start-[end] where start and end are both | |
548 | a memory unit (amount[KMG]). See also | |
549 | Documentation/kdump/kdump.txt for a example. | |
550 | ||
1da177e4 LT |
551 | cs4232= [HW,OSS] |
552 | Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq> | |
553 | ||
554 | cs89x0_dma= [HW,NET] | |
555 | Format: <dma> | |
556 | ||
557 | cs89x0_media= [HW,NET] | |
558 | Format: { rj45 | aui | bnc } | |
a9913044 | 559 | |
a9913044 | 560 | dasd= [HW,NET] |
1da177e4 LT |
561 | See header of drivers/s390/block/dasd_devmap.c. |
562 | ||
563 | db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port | |
564 | (one device per port) | |
565 | Format: <port#>,<type> | |
566 | See also Documentation/input/joystick-parport.txt | |
567 | ||
568 | debug [KNL] Enable kernel debugging (events log level). | |
569 | ||
cae2ed9a IM |
570 | debug_locks_verbose= |
571 | [KNL] verbose self-tests | |
572 | Format=<0|1> | |
573 | Print debugging info while doing the locking API | |
574 | self-tests. | |
575 | We default to 0 (no extra messages), setting it to | |
576 | 1 will print _a lot_ more information - normally | |
577 | only useful to kernel developers. | |
578 | ||
3ac7fe5a TG |
579 | debug_objects [KNL] Enable object debugging |
580 | ||
d3af01f1 TG |
581 | debugpat [X86] Enable PAT debugging |
582 | ||
2d27a966 | 583 | decnet.addr= [HW,NET] |
1da177e4 LT |
584 | Format: <area>[,<node>] |
585 | See also Documentation/networking/decnet.txt. | |
586 | ||
ecb77fa9 | 587 | vt.default_blu= [VT] |
55ff9780 AD |
588 | Format: <blue0>,<blue1>,<blue2>,...,<blue15> |
589 | Change the default blue palette of the console. | |
590 | This is a 16-member array composed of values | |
591 | ranging from 0-255. | |
592 | ||
ecb77fa9 | 593 | vt.default_grn= [VT] |
55ff9780 AD |
594 | Format: <green0>,<green1>,<green2>,...,<green15> |
595 | Change the default green palette of the console. | |
596 | This is a 16-member array composed of values | |
597 | ranging from 0-255. | |
598 | ||
ecb77fa9 | 599 | vt.default_red= [VT] |
55ff9780 AD |
600 | Format: <red0>,<red1>,<red2>,...,<red15> |
601 | Change the default red palette of the console. | |
602 | This is a 16-member array composed of values | |
603 | ranging from 0-255. | |
604 | ||
ecb77fa9 ST |
605 | vt.default_utf8= |
606 | [VT] | |
55ff9780 AD |
607 | Format=<0|1> |
608 | Set system-wide default UTF-8 mode for all tty's. | |
ecb77fa9 ST |
609 | Default is 1, i.e. UTF-8 mode is enabled for all |
610 | newly opened terminals. | |
55ff9780 | 611 | |
1da177e4 LT |
612 | dhash_entries= [KNL] |
613 | Set number of hash buckets for dentry cache. | |
a9913044 | 614 | |
1da177e4 LT |
615 | digi= [HW,SERIAL] |
616 | IO parameters + enable/disable command. | |
617 | ||
618 | digiepca= [HW,SERIAL] | |
619 | See drivers/char/README.epca and | |
620 | Documentation/digiepca.txt. | |
621 | ||
95ffa243 YL |
622 | disable_mtrr_cleanup [X86] |
623 | enable_mtrr_cleanup [X86] | |
624 | The kernel tries to adjust MTRR layout from continuous | |
625 | to discrete, to make X server driver able to add WB | |
626 | entry later. This parameter enables/disables that. | |
627 | ||
628 | mtrr_chunk_size=nn[KMG] [X86] | |
629 | used for mtrr cleanup. It is largest continous chunk | |
630 | that could hold holes aka. UC entries. | |
631 | ||
632 | mtrr_gran_size=nn[KMG] [X86] | |
12031a62 YL |
633 | Used for mtrr cleanup. It is granularity of mtrr block. |
634 | Default is 1. | |
635 | Large value could prevent small alignment from | |
636 | using up MTRRs. | |
637 | ||
638 | mtrr_spare_reg_nr=n [X86] | |
639 | Format: <integer> | |
640 | Range: 0,7 : spare reg number | |
641 | Default : 1 | |
642 | Used for mtrr cleanup. It is spare mtrr entries number. | |
643 | Set to 2 or more if your graphical card needs more. | |
95ffa243 | 644 | |
093af8d7 | 645 | disable_mtrr_trim [X86, Intel and AMD only] |
99fc8d42 JB |
646 | By default the kernel will trim any uncacheable |
647 | memory out of your available memory pool based on | |
648 | MTRR settings. This parameter disables that behavior, | |
649 | possibly causing your machine to run very slowly. | |
650 | ||
1da177e4 LT |
651 | dmasound= [HW,OSS] Sound subsystem buffers |
652 | ||
653 | dscc4.setup= [NET] | |
654 | ||
655 | dtc3181e= [HW,SCSI] | |
656 | ||
0ae53640 | 657 | earlyprintk= [X86-32,X86-64,SH,BLACKFIN] |
1da177e4 LT |
658 | earlyprintk=vga |
659 | earlyprintk=serial[,ttySn[,baudrate]] | |
660 | ||
a9913044 | 661 | Append ",keep" to not disable it when the real console |
1da177e4 LT |
662 | takes over. |
663 | ||
664 | Only vga or serial at a time, not both. | |
665 | ||
666 | Currently only ttyS0 and ttyS1 are supported. | |
667 | ||
668 | Interaction with the standard serial driver is not | |
669 | very good. | |
670 | ||
671 | The VGA output is eventually overwritten by the real | |
672 | console. | |
673 | ||
674 | eata= [HW,SCSI] | |
675 | ||
1da177e4 | 676 | edd= [EDD] |
8c4dd606 | 677 | Format: {"off" | "on" | "skip[mbr]"} |
1da177e4 | 678 | |
1da177e4 LT |
679 | eisa_irq_edge= [PARISC,HW] |
680 | See header of drivers/parisc/eisa.c. | |
681 | ||
cd4f0ef7 | 682 | elanfreq= [X86-32] |
1da177e4 | 683 | See comment before function elanfreq_setup() in |
71f77055 | 684 | arch/x86/kernel/cpu/cpufreq/elanfreq.c. |
1da177e4 LT |
685 | |
686 | elevator= [IOSCHED] | |
16ab3adf | 687 | Format: {"anticipatory" | "cfq" | "deadline" | "noop"} |
a9913044 RD |
688 | See Documentation/block/as-iosched.txt and |
689 | Documentation/block/deadline-iosched.txt for details. | |
690 | ||
cd4f0ef7 | 691 | elfcorehdr= [X86-32, X86_64] |
a9913044 | 692 | Specifies physical address of start of kernel core |
aac04b32 VG |
693 | image elf header. Generally kexec loader will |
694 | pass this option to capture kernel. | |
695 | See Documentation/kdump/kdump.txt for details. | |
1da177e4 LT |
696 | |
697 | enforcing [SELINUX] Set initial enforcing status. | |
698 | Format: {"0" | "1"} | |
699 | See security/selinux/Kconfig help text. | |
700 | 0 -- permissive (log only, no denials). | |
701 | 1 -- enforcing (deny and log). | |
702 | Default value is 0. | |
703 | Value can be changed at runtime via /selinux/enforce. | |
704 | ||
1da177e4 LT |
705 | es1371= [HW,OSS] |
706 | Format: <spdif>,[<nomix>,[<amplifier>]] | |
707 | See also header of sound/oss/es1371.c. | |
a9913044 | 708 | |
1da177e4 LT |
709 | ether= [HW,NET] Ethernet cards parameters |
710 | This option is obsoleted by the "netdev=" option, which | |
711 | has equivalent usage. See its documentation for details. | |
712 | ||
713 | eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog. | |
714 | Format: <io>[,<irq>] | |
715 | ||
de1ba09b AM |
716 | failslab= |
717 | fail_page_alloc= | |
718 | fail_make_request=[KNL] | |
719 | General fault injection mechanism. | |
720 | Format: <interval>,<probability>,<space>,<times> | |
721 | See also /Documentation/fault-injection/. | |
722 | ||
1da177e4 LT |
723 | fd_mcs= [HW,SCSI] |
724 | See header of drivers/scsi/fd_mcs.c. | |
725 | ||
726 | fdomain= [HW,SCSI] | |
727 | See header of drivers/scsi/fdomain.c. | |
728 | ||
729 | floppy= [HW] | |
730 | See Documentation/floppy.txt. | |
731 | ||
f13ae30e AC |
732 | force_pal_cache_flush |
733 | [IA-64] Avoid check_sal_cache_flush which may hang on | |
734 | buggy SAL_CACHE_FLUSH implementations. Using this | |
735 | parameter will force ia64_sal_cache_flush to call | |
736 | ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. | |
737 | ||
1da177e4 LT |
738 | gamecon.map[2|3]= |
739 | [HW,JOY] Multisystem joystick and NES/SNES/PSX pad | |
740 | support via parallel port (up to 5 devices per port) | |
741 | Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> | |
742 | See also Documentation/input/joystick-parport.txt | |
743 | ||
744 | gamma= [HW,DRM] | |
745 | ||
aaf23042 YL |
746 | gart_fix_e820= [X86_64] disable the fix e820 for K8 GART |
747 | Format: off | on | |
748 | default: on | |
749 | ||
1da177e4 LT |
750 | gdth= [HW,SCSI] |
751 | See header of drivers/scsi/gdth.c. | |
752 | ||
753 | gpt [EFI] Forces disk with valid GPT signature but | |
754 | invalid Protective MBR to be treated as GPT. | |
755 | ||
1da177e4 LT |
756 | gvp11= [HW,SCSI] |
757 | ||
758 | hashdist= [KNL,NUMA] Large hashes allocated during boot | |
759 | are distributed across NUMA nodes. Defaults on | |
760 | for IA-64, off otherwise. | |
a9913044 | 761 | Format: 0 | 1 (for off | on) |
1da177e4 LT |
762 | |
763 | hcl= [IA-64] SGI's Hardware Graph compatibility layer | |
764 | ||
765 | hd= [EIDE] (E)IDE hard drive subsystem geometry | |
766 | Format: <cyl>,<head>,<sect> | |
767 | ||
1da177e4 LT |
768 | highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact |
769 | size of <nn>. This works even on boxes that have no | |
770 | highmem otherwise. This also works to reduce highmem | |
771 | size on bigger boxes. | |
772 | ||
54cdfdb4 TG |
773 | highres= [KNL] Enable/disable high resolution timer mode. |
774 | Valid parameters: "on", "off" | |
775 | Default: "on" | |
776 | ||
1da177e4 LT |
777 | hisax= [HW,ISDN] |
778 | See Documentation/isdn/README.HiSax. | |
779 | ||
b4718e62 AK |
780 | hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. |
781 | hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. | |
0d9ea754 JT |
782 | On x86-64 and powerpc, this option can be specified |
783 | multiple times interleaved with hugepages= to reserve | |
784 | huge pages of different sizes. Valid pages sizes on | |
785 | x86-64 are 2M (when the CPU supports "pse") and 1G | |
786 | (when the CPU supports the "pdpe1gb" cpuinfo flag) | |
b4718e62 AK |
787 | Note that 1GB pages can only be allocated at boot time |
788 | using hugepages= and not freed afterwards. | |
e11bfbfc NP |
789 | default_hugepagesz= |
790 | [same as hugepagesz=] The size of the default | |
791 | HugeTLB page size. This is the size represented by | |
792 | the legacy /proc/ hugepages APIs, used for SHM, and | |
793 | default size when mounting hugetlbfs filesystems. | |
794 | Defaults to the default architecture's huge page size | |
795 | if not specified. | |
1da177e4 | 796 | |
1da177e4 | 797 | i8042.direct [HW] Put keyboard port into non-translated mode |
84eb8d06 ML |
798 | i8042.dumbkbd [HW] Pretend that controller can only read data from |
799 | keyboard and cannot control its state | |
1da177e4 LT |
800 | (Don't attempt to blink the leds) |
801 | i8042.noaux [HW] Don't check for auxiliary (== mouse) port | |
945ef0d4 | 802 | i8042.nokbd [HW] Don't check/create keyboard port |
75d08c78 JK |
803 | i8042.noloop [HW] Disable the AUX Loopback command while probing |
804 | for the AUX port | |
1da177e4 LT |
805 | i8042.nomux [HW] Don't check presence of an active multiplexing |
806 | controller | |
807 | i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX | |
808 | controllers | |
809 | i8042.panicblink= | |
810 | [HW] Frequency with which keyboard LEDs should blink | |
811 | when kernel panics (default is 0.5 sec) | |
812 | i8042.reset [HW] Reset the controller during init and cleanup | |
813 | i8042.unlock [HW] Unlock (ignore) the keylock | |
814 | ||
815 | i810= [HW,DRM] | |
816 | ||
e70c9d5e DT |
817 | i8k.ignore_dmi [HW] Continue probing hardware even if DMI data |
818 | indicates that the driver is running on unsupported | |
819 | hardware. | |
1da177e4 LT |
820 | i8k.force [HW] Activate i8k driver even if SMM BIOS signature |
821 | does not match list of supported models. | |
822 | i8k.power_status | |
823 | [HW] Report power status in /proc/i8k | |
824 | (disabled by default) | |
825 | i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN | |
826 | capability is set. | |
827 | ||
828 | ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter | |
829 | See Documentation/mca.txt. | |
830 | ||
831 | icn= [HW,ISDN] | |
832 | Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] | |
833 | ||
834 | ide= [HW] (E)IDE subsystem | |
a594eeb1 | 835 | Format: ide=nodma or ide=doubler |
1c10e938 | 836 | See Documentation/ide/ide.txt. |
1da177e4 | 837 | |
1da177e4 | 838 | idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed |
1c10e938 | 839 | See Documentation/ide/ide.txt. |
1da177e4 | 840 | |
f039b754 | 841 | idle= [X86] |
da5e09a1 | 842 | Format: idle=poll or idle=mwait, idle=halt, idle=nomwait |
f039b754 AK |
843 | Poll forces a polling idle loop that can slightly improves the performance |
844 | of waking up a idle CPU, but will use a lot of power and make the system | |
845 | run hot. Not recommended. | |
846 | idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose | |
847 | to not use it because it doesn't save as much power as a normal idle | |
848 | loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same | |
849 | as idle=poll. | |
c1e3b377 ZY |
850 | idle=halt. Halt is forced to be used for CPU idle. |
851 | In such case C2/C3 won't be used again. | |
da5e09a1 | 852 | idle=nomwait. Disable mwait for CPU C-states |
a9913044 | 853 | |
594765a7 DC |
854 | ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem |
855 | Claim all unknown PCI IDE storage controllers. | |
856 | ||
79290822 IM |
857 | ignore_loglevel [KNL] |
858 | Ignore loglevel setting - this will print /all/ | |
859 | kernel messages to the console. Useful for debugging. | |
860 | ||
1da177e4 LT |
861 | ihash_entries= [KNL] |
862 | Set number of hash buckets for inode cache. | |
863 | ||
864 | in2000= [HW,SCSI] | |
865 | See header of drivers/scsi/in2000.c. | |
866 | ||
867 | init= [KNL] | |
868 | Format: <full_path> | |
869 | Run specified binary instead of /sbin/init as init | |
870 | process. | |
871 | ||
872 | initcall_debug [KNL] Trace initcalls as they are executed. Useful | |
873 | for working out where the kernel is dying during | |
874 | startup. | |
875 | ||
876 | initrd= [BOOT] Specify the location of the initial ramdisk | |
877 | ||
878 | inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver | |
879 | Format: <irq> | |
880 | ||
881 | inttest= [IA64] | |
882 | ||
b552da87 PM |
883 | iommu= [x86] |
884 | off | |
885 | force | |
886 | noforce | |
887 | biomerge | |
888 | panic | |
889 | nopanic | |
890 | merge | |
891 | nomerge | |
892 | forcesac | |
893 | soft | |
894 | ||
895 | ||
ba395927 KA |
896 | intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option |
897 | off | |
898 | Disable intel iommu driver. | |
899 | igfx_off [Default Off] | |
900 | By default, gfx is mapped as normal device. If a gfx | |
901 | device has a dedicated DMAR unit, the DMAR unit is | |
902 | bypassed by not enabling DMAR with this option. In | |
903 | this case, gfx device will use physical address for | |
904 | DMA. | |
7d3b03ce KA |
905 | forcedac [x86_64] |
906 | With this option iommu will not optimize to look | |
907 | for io virtual address below 32 bit forcing dual | |
908 | address cycle on pci bus for cards supporting greater | |
909 | than 32 bit addressing. The default is to look | |
910 | for translation below 32 bit and if not available | |
911 | then look in the higher range. | |
5e0d2a6f | 912 | strict [Default Off] |
913 | With this option on every unmap_single operation will | |
914 | result in a hardware IOTLB flush operation as opposed | |
915 | to batching them for performance. | |
ba395927 | 916 | |
b02aae9c | 917 | io_delay= [X86-32,X86-64] I/O delay method |
6e7c4025 IM |
918 | 0x80 |
919 | Standard port 0x80 based delay | |
920 | 0xed | |
921 | Alternate port 0xed based delay (needed on some systems) | |
b02aae9c | 922 | udelay |
6e7c4025 IM |
923 | Simple two microseconds delay |
924 | none | |
925 | No delay | |
b02aae9c | 926 | |
1da177e4 LT |
927 | io7= [HW] IO7 for Marvel based alpha systems |
928 | See comment before marvel_specify_io7 in | |
929 | arch/alpha/kernel/core_marvel.c. | |
930 | ||
931 | ip= [IP_PNP] | |
6ded55da | 932 | See Documentation/filesystems/nfsroot.txt. |
1da177e4 LT |
933 | |
934 | ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards | |
c8facbb6 RD |
935 | See comment before ip2_setup() in |
936 | drivers/char/ip2/ip2base.c. | |
1da177e4 LT |
937 | |
938 | ips= [HW,SCSI] Adaptec / IBM ServeRAID controller | |
939 | See header of drivers/scsi/ips.c. | |
940 | ||
72c4a13a SH |
941 | ports= [IP_VS_FTP] IPVS ftp helper module |
942 | Default is 21. | |
943 | Up to 8 (IP_VS_APP_MAX_PORTS) ports | |
944 | may be specified. | |
945 | Format: <port>,<port>.... | |
946 | ||
200803df AC |
947 | irqfixup [HW] |
948 | When an interrupt is not handled search all handlers | |
949 | for it. Intended to get systems with badly broken | |
950 | firmware running. | |
951 | ||
952 | irqpoll [HW] | |
953 | When an interrupt is not handled search all handlers | |
954 | for it. Also check all handlers each timer | |
955 | interrupt. Intended to get systems with badly broken | |
956 | firmware running. | |
957 | ||
1da177e4 | 958 | isapnp= [ISAPNP] |
a9913044 | 959 | Format: <RDP>,<reset>,<pci_scan>,<verbosity> |
1da177e4 LT |
960 | |
961 | isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. | |
22f2e280 DF |
962 | Format: |
963 | <cpu number>,...,<cpu number> | |
964 | or | |
965 | <cpu number>-<cpu number> (must be a positive range in ascending order) | |
966 | or a mixture | |
967 | <cpu number>,...,<cpu number>-<cpu number> | |
1da177e4 LT |
968 | This option can be used to specify one or more CPUs |
969 | to isolate from the general SMP balancing and scheduling | |
970 | algorithms. The only way to move a process onto or off | |
971 | an "isolated" CPU is via the CPU affinity syscalls. | |
972 | <cpu number> begins at 0 and the maximum value is | |
973 | "number of CPUs in system - 1". | |
974 | ||
975 | This option is the preferred way to isolate CPUs. The | |
a9913044 RD |
976 | alternative -- manually setting the CPU mask of all |
977 | tasks in the system -- can cause problems and | |
978 | suboptimal load balancer performance. | |
1da177e4 | 979 | |
a9913044 | 980 | iucv= [HW,NET] |
1da177e4 LT |
981 | |
982 | js= [HW,JOY] Analog joystick | |
983 | See Documentation/input/joystick.txt. | |
984 | ||
cd4f0ef7 | 985 | kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter |
ed7ed365 MG |
986 | specifies the amount of memory usable by the kernel |
987 | for non-movable allocations. The requested amount is | |
988 | spread evenly throughout all nodes in the system. The | |
989 | remaining memory in each node is used for Movable | |
990 | pages. In the event, a node is too small to have both | |
991 | kernelcore and Movable pages, kernelcore pages will | |
992 | take priority and other nodes will have a larger number | |
993 | of kernelcore pages. The Movable zone is used for the | |
994 | allocation of pages that may be reclaimed or moved | |
995 | by the page migration subsystem. This means that | |
996 | HugeTLB pages may not be allocated from this zone. | |
997 | Note that allocations like PTEs-from-HighMem still | |
998 | use the HighMem zone if it exists, and the Normal | |
999 | zone if it does not. | |
1000 | ||
cd4f0ef7 | 1001 | movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter |
7e63efef MG |
1002 | is similar to kernelcore except it specifies the |
1003 | amount of memory used for migratable allocations. | |
1004 | If both kernelcore and movablecore is specified, | |
1005 | then kernelcore will be at *least* the specified | |
1006 | value but may be more. If movablecore on its own | |
1007 | is specified, the administrator must be careful | |
1008 | that the amount of memory usable for all allocations | |
1009 | is not too small. | |
1010 | ||
1da177e4 LT |
1011 | keepinitrd [HW,ARM] |
1012 | ||
cd4f0ef7 | 1013 | kstack=N [X86-32,X86-64] Print N words from the kernel stack |
1da177e4 LT |
1014 | in oops dumps. |
1015 | ||
6cdf6e06 JW |
1016 | kgdboc= [HW] kgdb over consoles. |
1017 | Requires a tty driver that supports console polling. | |
1018 | (only serial suported for now) | |
1019 | Format: <serial_device>[,baud] | |
1020 | ||
1da177e4 LT |
1021 | l2cr= [PPC] |
1022 | ||
a78bfbfc RB |
1023 | l3cr= [PPC] |
1024 | ||
cd4f0ef7 | 1025 | lapic [X86-32,APIC] Enable the local APIC even if BIOS |
a9913044 | 1026 | disabled it. |
1da177e4 | 1027 | |
cd4f0ef7 | 1028 | lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in |
e585bef8 TG |
1029 | C2 power state. |
1030 | ||
fcb71f6f FC |
1031 | libata.dma= [LIBATA] DMA control |
1032 | libata.dma=0 Disable all PATA and SATA DMA | |
1033 | libata.dma=1 PATA and SATA Disk DMA only | |
1034 | libata.dma=2 ATAPI (CDROM) DMA only | |
1035 | libata.dma=4 Compact Flash DMA only | |
1036 | Combinations also work, so libata.dma=3 enables DMA | |
1037 | for disks and CDROMs, but not CFs. | |
1038 | ||
78e70c23 DJ |
1039 | libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume |
1040 | when set. | |
1041 | Format: <int> | |
1042 | ||
33267325 TH |
1043 | libata.force= [LIBATA] Force configurations. The format is comma |
1044 | separated list of "[ID:]VAL" where ID is | |
1045 | PORT[:DEVICE]. PORT and DEVICE are decimal numbers | |
1046 | matching port, link or device. Basically, it matches | |
1047 | the ATA ID string printed on console by libata. If | |
1048 | the whole ID part is omitted, the last PORT and DEVICE | |
1049 | values are used. If ID hasn't been specified yet, the | |
1050 | configuration applies to all ports, links and devices. | |
1051 | ||
1052 | If only DEVICE is omitted, the parameter applies to | |
1053 | the port and all links and devices behind it. DEVICE | |
1054 | number of 0 either selects the first device or the | |
1055 | first fan-out link behind PMP device. It does not | |
1056 | select the host link. DEVICE number of 15 selects the | |
1057 | host link and device attached to it. | |
1058 | ||
1059 | The VAL specifies the configuration to force. As long | |
1060 | as there's no ambiguity shortcut notation is allowed. | |
1061 | For example, both 1.5 and 1.5G would work for 1.5Gbps. | |
1062 | The following configurations can be forced. | |
1063 | ||
1064 | * Cable type: 40c, 80c, short40c, unk, ign or sata. | |
1065 | Any ID with matching PORT is used. | |
1066 | ||
1067 | * SATA link speed limit: 1.5Gbps or 3.0Gbps. | |
1068 | ||
1069 | * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. | |
1070 | udma[/][16,25,33,44,66,100,133] notation is also | |
1071 | allowed. | |
1072 | ||
1073 | * [no]ncq: Turn on or off NCQ. | |
1074 | ||
1075 | If there are multiple matching configurations changing | |
1076 | the same attribute, the last one is used. | |
1077 | ||
1da177e4 LT |
1078 | load_ramdisk= [RAM] List of ramdisks to load from floppy |
1079 | See Documentation/ramdisk.txt. | |
1080 | ||
a6b25b67 RD |
1081 | lockd.nlm_grace_period=P [NFS] Assign grace period. |
1082 | Format: <integer> | |
1da177e4 | 1083 | |
a6b25b67 RD |
1084 | lockd.nlm_tcpport=N [NFS] Assign TCP port. |
1085 | Format: <integer> | |
1086 | ||
1087 | lockd.nlm_timeout=T [NFS] Assign timeout value. | |
1088 | Format: <integer> | |
1089 | ||
1090 | lockd.nlm_udpport=M [NFS] Assign UDP port. | |
1091 | Format: <integer> | |
1da177e4 LT |
1092 | |
1093 | logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver | |
1094 | Format: <irq> | |
1095 | ||
1096 | loglevel= All Kernel Messages with a loglevel smaller than the | |
1097 | console loglevel will be printed to the console. It can | |
1098 | also be changed with klogd or other programs. The | |
1099 | loglevels are defined as follows: | |
1100 | ||
1101 | 0 (KERN_EMERG) system is unusable | |
1102 | 1 (KERN_ALERT) action must be taken immediately | |
1103 | 2 (KERN_CRIT) critical conditions | |
1104 | 3 (KERN_ERR) error conditions | |
1105 | 4 (KERN_WARNING) warning conditions | |
1106 | 5 (KERN_NOTICE) normal but significant condition | |
1107 | 6 (KERN_INFO) informational | |
1108 | 7 (KERN_DEBUG) debug-level messages | |
1109 | ||
1110 | log_buf_len=n Sets the size of the printk ring buffer, in bytes. | |
a9913044 RD |
1111 | Format: { n | nk | nM } |
1112 | n must be a power of two. The default size | |
1113 | is set in the kernel config file. | |
1da177e4 | 1114 | |
accaa24c RD |
1115 | logo.nologo [FB] Disables display of the built-in Linux logo. |
1116 | This may be used to provide more screen space for | |
1117 | kernel log messages and is useful when debugging | |
1118 | kernel boot problems. | |
1119 | ||
1da177e4 LT |
1120 | lp=0 [LP] Specify parallel ports to use, e.g, |
1121 | lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses | |
1122 | lp=reset first parallel port). 'lp=0' disables the | |
1123 | lp=auto printer driver. 'lp=reset' (which can be | |
1124 | specified in addition to the ports) causes | |
1125 | attached printers to be reset. Using | |
1126 | lp=port1,port2,... specifies the parallel ports | |
1127 | to associate lp devices with, starting with | |
1128 | lp0. A port specification may be 'none' to skip | |
1129 | that lp device, or a parport name such as | |
1130 | 'parport0'. Specifying 'lp=auto' instead of a | |
1131 | port specification list means that device IDs | |
1132 | from each port should be examined, to see if | |
1133 | an IEEE 1284-compliant printer is attached; if | |
1134 | so, the driver will manage that printer. | |
1135 | See also header of drivers/char/lp.c. | |
1136 | ||
1137 | lpj=n [KNL] | |
1138 | Sets loops_per_jiffy to given constant, thus avoiding | |
1139 | time-consuming boot-time autodetection (up to 250 ms per | |
1140 | CPU). 0 enables autodetection (default). To determine | |
1141 | the correct value for your kernel, boot with normal | |
1142 | autodetection and see what value is printed. Note that | |
1143 | on SMP systems the preset will be applied to all CPUs, | |
1144 | which is likely to cause problems if your CPUs need | |
1145 | significantly divergent settings. An incorrect value | |
1146 | will cause delays in the kernel to be wrong, leading to | |
1147 | unpredictable I/O errors and other breakage. Although | |
1148 | unlikely, in the extreme case this might damage your | |
1149 | hardware. | |
1150 | ||
1151 | ltpc= [NET] | |
1152 | Format: <io>,<irq>,<dma> | |
1153 | ||
a9913044 RD |
1154 | mac5380= [HW,SCSI] Format: |
1155 | <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags> | |
1da177e4 | 1156 | |
a9913044 RD |
1157 | machvec= [IA64] Force the use of a particular machine-vector |
1158 | (machvec) in a generic kernel. | |
1159 | Example: machvec=hpzx1_swiotlb | |
1da177e4 | 1160 | |
a9913044 | 1161 | max_loop= [LOOP] Maximum number of loopback devices that can |
1da177e4 LT |
1162 | be mounted |
1163 | Format: <1-256> | |
1164 | ||
1165 | maxcpus= [SMP] Maximum number of processors that an SMP kernel | |
61ec7567 LB |
1166 | should make use of. maxcpus=n : n >= 0 limits the |
1167 | kernel to using 'n' processors. n=0 is a special case, | |
1168 | it is equivalent to "nosmp", which also disables | |
1169 | the IO APIC. | |
1da177e4 | 1170 | |
2b2c3750 BP |
1171 | max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or |
1172 | equal to this physical address is ignored. | |
1173 | ||
a9913044 | 1174 | max_luns= [SCSI] Maximum number of LUNs to probe. |
1da177e4 LT |
1175 | Should be between 1 and 2^32-1. |
1176 | ||
1177 | max_report_luns= | |
a9913044 | 1178 | [SCSI] Maximum number of LUNs received. |
1da177e4 LT |
1179 | Should be between 1 and 16384. |
1180 | ||
1da177e4 LT |
1181 | mcatest= [IA-64] |
1182 | ||
cd4f0ef7 | 1183 | mce [X86-32] Machine Check Exception |
1da177e4 | 1184 | |
909dd324 AK |
1185 | mce=option [X86-64] See Documentation/x86_64/boot-options.txt |
1186 | ||
1da177e4 LT |
1187 | md= [HW] RAID subsystems devices and level |
1188 | See Documentation/md.txt. | |
a9913044 | 1189 | |
1da177e4 LT |
1190 | mdacon= [MDA] |
1191 | Format: <first>,<last> | |
1192 | Specifies range of consoles to be captured by the MDA. | |
a9913044 | 1193 | |
1da177e4 LT |
1194 | mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory |
1195 | Amount of memory to be used when the kernel is not able | |
1196 | to see the whole system memory or for test. | |
cd4f0ef7 | 1197 | [X86-32] Use together with memmap= to avoid physical |
1da177e4 LT |
1198 | address space collisions. Without memmap= PCI devices |
1199 | could be placed at addresses belonging to unused RAM. | |
1200 | ||
cd4f0ef7 | 1201 | mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel |
1da177e4 LT |
1202 | memory. |
1203 | ||
cd4f0ef7 | 1204 | memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact |
1da177e4 LT |
1205 | E820 memory map, as specified by the user. |
1206 | Such memmap=exactmap lines can be constructed based on | |
1207 | BIOS output or other requirements. See the memmap=nn@ss | |
1208 | option description. | |
1209 | ||
1210 | memmap=nn[KMG]@ss[KMG] | |
1211 | [KNL] Force usage of a specific region of memory | |
1212 | Region of memory to be used, from ss to ss+nn. | |
1213 | ||
1214 | memmap=nn[KMG]#ss[KMG] | |
1215 | [KNL,ACPI] Mark specific memory as ACPI data. | |
1216 | Region of memory to be used, from ss to ss+nn. | |
1217 | ||
1218 | memmap=nn[KMG]$ss[KMG] | |
1219 | [KNL,ACPI] Mark specific memory as reserved. | |
1220 | Region of memory to be used, from ss to ss+nn. | |
1312848e PM |
1221 | Example: Exclude memory from 0x18690000-0x1869ffff |
1222 | memmap=64K$0x18690000 | |
1223 | or | |
1224 | memmap=0x10000$0x18690000 | |
1da177e4 | 1225 | |
caadbdce | 1226 | memtest= [KNL,X86] Enable memtest |
c64df707 YL |
1227 | Format: <integer> |
1228 | range: 0,4 : pattern number | |
1229 | default : 0 <disable> | |
1230 | ||
1da177e4 LT |
1231 | meye.*= [HW] Set MotionEye Camera parameters |
1232 | See Documentation/video4linux/meye.txt. | |
1233 | ||
8f36881b AS |
1234 | mfgpt_irq= [IA-32] Specify the IRQ to use for the |
1235 | Multi-Function General Purpose Timers on AMD Geode | |
1236 | platforms. | |
1237 | ||
e6c4dc6c WT |
1238 | mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when |
1239 | the BIOS has incorrectly applied a workaround. TinyBIOS | |
1240 | version 0.98 is known to be affected, 0.99 fixes the | |
1241 | problem by letting the user disable the workaround. | |
1242 | ||
1da177e4 LT |
1243 | mga= [HW,DRM] |
1244 | ||
6b74ab97 MG |
1245 | mminit_loglevel= |
1246 | [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this | |
1247 | parameter allows control of the logging verbosity for | |
1248 | the additional memory initialisation checks. A value | |
1249 | of 0 disables mminit logging and a level of 4 will | |
1250 | log everything. Information is printed at KERN_DEBUG | |
1251 | so loglevel=8 may also need to be specified. | |
1252 | ||
1da177e4 LT |
1253 | mousedev.tap_time= |
1254 | [MOUSE] Maximum time between finger touching and | |
1255 | leaving touchpad surface for touch to be considered | |
1256 | a tap and be reported as a left button click (for | |
1257 | touchpads working in absolute mode only). | |
1258 | Format: <msecs> | |
1259 | mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices | |
1260 | reporting absolute coordinates, such as tablets | |
1261 | mousedev.yres= [MOUSE] Vertical screen resolution, used for devices | |
1262 | reporting absolute coordinates, such as tablets | |
1263 | ||
1264 | mpu401= [HW,OSS] | |
1265 | Format: <io>,<irq> | |
1266 | ||
1267 | MTD_Partition= [MTD] | |
1268 | Format: <name>,<region-number>,<size>,<offset> | |
1269 | ||
a9913044 RD |
1270 | MTD_Region= [MTD] Format: |
1271 | <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] | |
1da177e4 LT |
1272 | |
1273 | mtdparts= [MTD] | |
c8facbb6 | 1274 | See drivers/mtd/cmdlinepart.c. |
1da177e4 | 1275 | |
9db829f4 BD |
1276 | mtdset= [ARM] |
1277 | ARM/S3C2412 JIVE boot control | |
1278 | ||
1279 | See arch/arm/mach-s3c2412/mach-jive.c | |
1280 | ||
1da177e4 | 1281 | mtouchusb.raw_coordinates= |
a9913044 RD |
1282 | [HW] Make the MicroTouch USB driver use raw coordinates |
1283 | ('y', default) or cooked coordinates ('n') | |
1da177e4 LT |
1284 | |
1285 | n2= [NET] SDL Inc. RISCom/N2 synchronous serial card | |
1286 | ||
1287 | NCR_D700= [HW,SCSI] | |
1288 | See header of drivers/scsi/NCR_D700.c. | |
1289 | ||
1290 | ncr5380= [HW,SCSI] | |
1291 | ||
1292 | ncr53c400= [HW,SCSI] | |
1293 | ||
1294 | ncr53c400a= [HW,SCSI] | |
1295 | ||
1296 | ncr53c406a= [HW,SCSI] | |
1297 | ||
1298 | ncr53c8xx= [HW,SCSI] | |
1299 | ||
1300 | netdev= [NET] Network devices parameters | |
1301 | Format: <irq>,<io>,<mem_start>,<mem_end>,<name> | |
1302 | Note that mem_start is often overloaded to mean | |
1303 | something different and driver-specific. | |
a9913044 RD |
1304 | This usage is only documented in each driver source |
1305 | file if at all. | |
1306 | ||
58401572 KPO |
1307 | nf_conntrack.acct= |
1308 | [NETFILTER] Enable connection tracking flow accounting | |
1309 | 0 to disable accounting | |
1310 | 1 to enable accounting | |
1311 | Default value depends on CONFIG_NF_CT_ACCT that is | |
1312 | going to be removed in 2.6.29. | |
1313 | ||
1da177e4 | 1314 | nfsaddrs= [NFS] |
6ded55da | 1315 | See Documentation/filesystems/nfsroot.txt. |
1da177e4 LT |
1316 | |
1317 | nfsroot= [NFS] nfs root filesystem for disk-less boxes. | |
6ded55da | 1318 | See Documentation/filesystems/nfsroot.txt. |
1da177e4 | 1319 | |
a72b4422 TM |
1320 | nfs.callback_tcpport= |
1321 | [NFS] set the TCP port on which the NFSv4 callback | |
1322 | channel should listen. | |
1323 | ||
58df095b TM |
1324 | nfs.idmap_cache_timeout= |
1325 | [NFS] set the maximum lifetime for idmapper cache | |
1326 | entries. | |
1327 | ||
f43bf0be TM |
1328 | nfs.enable_ino64= |
1329 | [NFS] enable 64-bit inode numbers. | |
1330 | If zero, the NFS client will fake up a 32-bit inode | |
1331 | number for the readdir() and stat() syscalls instead | |
1332 | of returning the full 64-bit number. | |
1333 | The default is to return 64-bit inode numbers. | |
1334 | ||
e7ba176b HS |
1335 | nmi_debug= [KNL,AVR32] Specify one or more actions to take |
1336 | when a NMI is triggered. | |
1337 | Format: [state][,regs][,debounce][,die] | |
1338 | ||
cd4f0ef7 | 1339 | nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels |
1da177e4 | 1340 | |
cd4f0ef7 | 1341 | no387 [BUGS=X86-32] Tells the kernel to use the 387 maths |
1da177e4 LT |
1342 | emulation library even if a 387 maths coprocessor |
1343 | is present. | |
1344 | ||
c1aee215 CL |
1345 | noaliencache [MM, NUMA, SLAB] Disables the allocation of alien |
1346 | caches in the slab allocator. Saves per-node memory, | |
1347 | but will impact performance. | |
3395ee05 | 1348 | |
a9913044 RD |
1349 | noalign [KNL,ARM] |
1350 | ||
1da177e4 LT |
1351 | noapic [SMP,APIC] Tells the kernel to not make use of any |
1352 | IOAPICs that may be present in the system. | |
1353 | ||
1da177e4 LT |
1354 | nobats [PPC] Do not use BATs for mapping kernel lowmem |
1355 | on "Classic" PPC cores. | |
1356 | ||
1357 | nocache [ARM] | |
a9913044 | 1358 | |
163ecdff SN |
1359 | nodelayacct [KNL] Disable per-task delay accounting |
1360 | ||
1da177e4 LT |
1361 | nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. |
1362 | ||
8b2cb7a8 HY |
1363 | noefi [X86-32,X86-64] Disable EFI runtime services support. |
1364 | ||
1da177e4 LT |
1365 | noexec [IA-64] |
1366 | ||
cd4f0ef7 | 1367 | noexec [X86-32,X86-64] |
f5a1b191 | 1368 | On X86-32 available only on PAE configured kernels. |
1da177e4 | 1369 | noexec=on: enable non-executable mappings (default) |
f5a1b191 JS |
1370 | noexec=off: disable non-executable mappings |
1371 | ||
1372 | noexec32 [X86-64] | |
1373 | This affects only 32-bit executables. | |
1374 | noexec32=on: enable non-executable mappings (default) | |
1375 | read doesn't imply executable mappings | |
1376 | noexec32=off: disable non-executable mappings | |
1377 | read implies executable mappings | |
1da177e4 | 1378 | |
cd4f0ef7 | 1379 | nofxsr [BUGS=X86-32] Disables x86 floating point extended |
4f886511 CE |
1380 | register save and restore. The kernel will only save |
1381 | legacy floating-point registers on task switch. | |
1da177e4 | 1382 | |
191679fd AK |
1383 | noclflush [BUGS=X86] Don't use the CLFLUSH instruction |
1384 | ||
1da177e4 | 1385 | nohlt [BUGS=ARM] |
a9913044 | 1386 | |
cd4f0ef7 | 1387 | no-hlt [BUGS=X86-32] Tells the kernel that the hlt |
1da177e4 LT |
1388 | instruction doesn't work correctly and not to |
1389 | use it. | |
1390 | ||
1391 | nohalt [IA-64] Tells the kernel not to use the power saving | |
1392 | function PAL_HALT_LIGHT when idle. This increases | |
1393 | power-consumption. On the positive side, it reduces | |
1394 | interrupt wake-up latency, which may improve performance | |
1395 | in certain environments such as networked servers or | |
1396 | real-time systems. | |
1397 | ||
79bf2bb3 TG |
1398 | nohz= [KNL] Boottime enable/disable dynamic ticks |
1399 | Valid arguments: on, off | |
1400 | Default: on | |
1401 | ||
cd4f0ef7 | 1402 | noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing |
8542b200 | 1403 | |
cd4f0ef7 | 1404 | noirqdebug [X86-32] Disables the code which attempts to detect and |
1da177e4 LT |
1405 | disable unhandled interrupt sources. |
1406 | ||
cd4f0ef7 | 1407 | no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for |
8542b200 ZA |
1408 | broken timer IRQ sources. |
1409 | ||
1da177e4 LT |
1410 | noisapnp [ISAPNP] Disables ISA PnP code. |
1411 | ||
1412 | noinitrd [RAM] Tells the kernel not to load any configured | |
1413 | initial RAM disk. | |
1414 | ||
1415 | nointroute [IA-64] | |
1416 | ||
0aa366f3 TL |
1417 | nojitter [IA64] Disables jitter checking for ITC timers. |
1418 | ||
cd4f0ef7 | 1419 | nolapic [X86-32,APIC] Do not enable or use the local APIC. |
1da177e4 | 1420 | |
cd4f0ef7 | 1421 | nolapic_timer [X86-32,APIC] Do not use the local APIC timer. |
ad62ca2b | 1422 | |
1da177e4 LT |
1423 | noltlbs [PPC] Do not use large page/tlb entries for kernel |
1424 | lowmem mapping on PPC40x. | |
1425 | ||
312f1f01 H |
1426 | nomca [IA-64] Disable machine check abort handling |
1427 | ||
cd4f0ef7 | 1428 | nomce [X86-32] Machine Check Exception |
abe37e5a | 1429 | |
83d7384f AS |
1430 | nomfgpt [X86-32] Disable Multi-Function General Purpose |
1431 | Timer usage (for AMD Geode machines). | |
1432 | ||
cd4f0ef7 | 1433 | noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops |
959b4fdf | 1434 | |
cd4f0ef7 | 1435 | noreplace-smp [X86-32,SMP] Don't replace SMP instructions |
b7fb4af0 JF |
1436 | with UP alternatives |
1437 | ||
1da177e4 LT |
1438 | noresidual [PPC] Don't use residual data on PReP machines. |
1439 | ||
a9913044 RD |
1440 | noresume [SWSUSP] Disables resume and restores original swap |
1441 | space. | |
1442 | ||
1da177e4 LT |
1443 | no-scroll [VGA] Disables scrollback. |
1444 | This is required for the Braillex ib80-piezo Braille | |
1445 | reader made by F.H. Papenmeier (Germany). | |
1446 | ||
1447 | nosbagart [IA-64] | |
1448 | ||
cd4f0ef7 | 1449 | nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. |
4f886511 | 1450 | |
61ec7567 LB |
1451 | nosmp [SMP] Tells an SMP kernel to act as a UP kernel, |
1452 | and disable the IO APIC. legacy for "maxcpus=0". | |
1da177e4 | 1453 | |
97842216 DJ |
1454 | nosoftlockup [KNL] Disable the soft-lockup detector. |
1455 | ||
1da177e4 LT |
1456 | nosync [HW,M68K] Disables sync negotiation for all devices. |
1457 | ||
cd4f0ef7 | 1458 | notsc [BUGS=X86-32] Disable Time Stamp Counter |
1da177e4 LT |
1459 | |
1460 | nousb [USB] Disable the USB subsystem | |
1461 | ||
1462 | nowb [ARM] | |
a9913044 | 1463 | |
a6c75b86 FY |
1464 | nptcg= [IA64] Override max number of concurrent global TLB |
1465 | purges which is reported from either PAL_VM_SUMMARY or | |
1466 | SAL PALO. | |
1467 | ||
f0c0b2b8 KH |
1468 | numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. |
1469 | one of ['zone', 'node', 'default'] can be specified | |
1470 | This can be set from sysctl after boot. | |
1471 | See Documentation/sysctl/vm.txt for details. | |
1472 | ||
a61c2d78 DJ |
1473 | nr_uarts= [SERIAL] maximum number of UARTs to be registered. |
1474 | ||
3ef0e1f8 AS |
1475 | olpc_ec_timeout= [OLPC] ms delay when issuing EC commands |
1476 | Rather than timing out after 20 ms if an EC | |
1477 | command is not properly ACKed, override the length | |
1478 | of the timeout. We have interrupts disabled while | |
1479 | waiting for the ACK, so if this is set too high | |
1480 | interrupts *may* be lost! | |
1481 | ||
1da177e4 LT |
1482 | opl3= [HW,OSS] |
1483 | Format: <io> | |
1484 | ||
1da177e4 LT |
1485 | oprofile.timer= [HW] |
1486 | Use timer interrupt instead of performance counters | |
1487 | ||
1da177e4 LT |
1488 | osst= [HW,SCSI] SCSI Tape Driver |
1489 | Format: <buffer_size>,<write_threshold> | |
1490 | See also Documentation/scsi/st.txt. | |
1491 | ||
1492 | panic= [KNL] Kernel behaviour on panic | |
1493 | Format: <timeout> | |
1494 | ||
1495 | parkbd.port= [HW] Parallel port number the keyboard adapter is | |
1496 | connected to, default is 0. | |
1497 | Format: <parport#> | |
1498 | parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, | |
1499 | 0 for XT, 1 for AT (default is AT). | |
a9913044 RD |
1500 | Format: <mode> |
1501 | ||
1502 | parport= [HW,PPT] Specify parallel ports. 0 disables. | |
1503 | Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } | |
1504 | Use 'auto' to force the driver to use any | |
1505 | IRQ/DMA settings detected (the default is to | |
1506 | ignore detected IRQ/DMA settings because of | |
1507 | possible conflicts). You can specify the base | |
1508 | address, IRQ, and DMA settings; IRQ and DMA | |
1509 | should be numbers, or 'auto' (for using detected | |
1510 | settings on that particular port), or 'nofifo' | |
1511 | (to avoid using a FIFO even if it is detected). | |
1512 | Parallel ports are assigned in the order they | |
1513 | are specified on the command line, starting | |
1514 | with parport0. | |
1515 | ||
1516 | parport_init_mode= [HW,PPT] | |
1517 | Configure VIA parallel port to operate in | |
1518 | a specific mode. This is necessary on Pegasos | |
1519 | computer where firmware has no options for setting | |
1520 | up parallel port mode and sets it to spp. | |
1521 | Currently this function knows 686a and 8231 chips. | |
1da177e4 LT |
1522 | Format: [spp|ps2|epp|ecp|ecpepp] |
1523 | ||
a9913044 RD |
1524 | pas2= [HW,OSS] Format: |
1525 | <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16> | |
1526 | ||
1da177e4 LT |
1527 | pas16= [HW,SCSI] |
1528 | See header of drivers/scsi/pas16.c. | |
1529 | ||
dd287796 AM |
1530 | pause_on_oops= |
1531 | Halt all CPUs after the first oops has been printed for | |
1532 | the specified number of seconds. This is to be used if | |
1533 | your oopses keep scrolling off the screen. | |
1534 | ||
1da177e4 LT |
1535 | pcbit= [HW,ISDN] |
1536 | ||
1537 | pcd. [PARIDE] | |
1538 | See header of drivers/block/paride/pcd.c. | |
1539 | See also Documentation/paride.txt. | |
1540 | ||
a9913044 | 1541 | pci=option[,option...] [PCI] various PCI subsystem options: |
cd4f0ef7 AC |
1542 | off [X86-32] don't probe for the PCI bus |
1543 | bios [X86-32] force use of PCI BIOS, don't access | |
a9913044 RD |
1544 | the hardware directly. Use this if your machine |
1545 | has a non-standard PCI host bridge. | |
cd4f0ef7 | 1546 | nobios [X86-32] disallow use of PCI BIOS, only direct |
a9913044 RD |
1547 | hardware access methods are allowed. Use this |
1548 | if you experience crashes upon bootup and you | |
1549 | suspect they are caused by the BIOS. | |
cd4f0ef7 | 1550 | conf1 [X86-32] Force use of PCI Configuration |
a9913044 | 1551 | Mechanism 1. |
cd4f0ef7 | 1552 | conf2 [X86-32] Force use of PCI Configuration |
a9913044 | 1553 | Mechanism 2. |
7f785763 RD |
1554 | noaer [PCIE] If the PCIEAER kernel config parameter is |
1555 | enabled, this kernel boot option can be used to | |
1556 | disable the use of PCIE advanced error reporting. | |
32a2eea7 JG |
1557 | nodomains [PCI] Disable support for multiple PCI |
1558 | root domains (aka PCI segments, in ACPI-speak). | |
cd4f0ef7 | 1559 | nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI |
61be6d66 | 1560 | Configuration |
309e57df MW |
1561 | nomsi [MSI] If the PCI_MSI kernel config parameter is |
1562 | enabled, this kernel boot option can be used to | |
1563 | disable the use of MSI interrupts system-wide. | |
cd4f0ef7 | 1564 | biosirq [X86-32] Use PCI BIOS calls to get the interrupt |
a9913044 RD |
1565 | routing table. These calls are known to be buggy |
1566 | on several machines and they hang the machine | |
1567 | when used, but on other computers it's the only | |
1568 | way to get the interrupt routing table. Try | |
1569 | this option if the kernel is unable to allocate | |
1570 | IRQs or discover secondary PCI buses on your | |
1571 | motherboard. | |
cd4f0ef7 | 1572 | rom [X86-32] Assign address space to expansion ROMs. |
a9913044 RD |
1573 | Use with caution as certain devices share |
1574 | address decoders between ROMs and other | |
1575 | resources. | |
bb71ad88 GH |
1576 | norom [X86-32,X86_64] Do not assign address space to |
1577 | expansion ROMs that do not already have | |
1578 | BIOS assigned address ranges. | |
cd4f0ef7 | 1579 | irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be |
a9913044 RD |
1580 | assigned automatically to PCI devices. You can |
1581 | make the kernel exclude IRQs of your ISA cards | |
1582 | this way. | |
cd4f0ef7 | 1583 | pirqaddr=0xAAAAA [X86-32] Specify the physical address |
a9913044 RD |
1584 | of the PIRQ table (normally generated |
1585 | by the BIOS) if it is outside the | |
1586 | F0000h-100000h range. | |
cd4f0ef7 | 1587 | lastbus=N [X86-32] Scan all buses thru bus #N. Can be |
a9913044 RD |
1588 | useful if the kernel is unable to find your |
1589 | secondary buses and you want to tell it | |
1590 | explicitly which ones they are. | |
cd4f0ef7 | 1591 | assign-busses [X86-32] Always assign all PCI bus |
a9913044 RD |
1592 | numbers ourselves, overriding |
1593 | whatever the firmware may have done. | |
cd4f0ef7 | 1594 | usepirqmask [X86-32] Honor the possible IRQ mask stored |
a9913044 RD |
1595 | in the BIOS $PIR table. This is needed on |
1596 | some systems with broken BIOSes, notably | |
1597 | some HP Pavilion N5400 and Omnibook XE3 | |
1598 | notebooks. This will have no effect if ACPI | |
1599 | IRQ routing is enabled. | |
cd4f0ef7 | 1600 | noacpi [X86-32] Do not use ACPI for IRQ routing |
a9913044 | 1601 | or for PCI scanning. |
62f420f8 GH |
1602 | use_crs [X86-32] Use _CRS for PCI resource |
1603 | allocation. | |
a9913044 RD |
1604 | routeirq Do IRQ routing for all PCI devices. |
1605 | This is normally done in pci_enable_device(), | |
1606 | so this option is a temporary workaround | |
1607 | for broken drivers that don't call it. | |
13a6ddb0 YL |
1608 | skip_isa_align [X86] do not align io start addr, so can |
1609 | handle more pci cards | |
a9913044 RD |
1610 | firmware [ARM] Do not re-enumerate the bus but instead |
1611 | just use the configuration from the | |
1612 | bootloader. This is currently used on | |
1613 | IXP2000 systems where the bus has to be | |
1614 | configured a certain way for adjunct CPUs. | |
0637a70a AK |
1615 | noearly [X86] Don't do any early type 1 scanning. |
1616 | This might help on some broken boards which | |
1617 | machine check when some devices' config space | |
1618 | is read. But various workarounds are disabled | |
1619 | and some IOMMU drivers will not work. | |
6b4b78fe MD |
1620 | bfsort Sort PCI devices into breadth-first order. |
1621 | This sorting is done to get a device | |
1622 | order compatible with older (<= 2.4) kernels. | |
1623 | nobfsort Don't sort PCI devices into breadth-first order. | |
4516a618 AN |
1624 | cbiosize=nn[KMG] The fixed amount of bus space which is |
1625 | reserved for the CardBus bridge's IO window. | |
1626 | The default value is 256 bytes. | |
1627 | cbmemsize=nn[KMG] The fixed amount of bus space which is | |
1628 | reserved for the CardBus bridge's memory | |
1629 | window. The default value is 64 megabytes. | |
6b4b78fe | 1630 | |
1da177e4 LT |
1631 | pcmv= [HW,PCMCIA] BadgePAD 4 |
1632 | ||
1633 | pd. [PARIDE] | |
1634 | See Documentation/paride.txt. | |
1635 | ||
1636 | pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at | |
1637 | boot time. | |
1638 | Format: { 0 | 1 } | |
1639 | See arch/parisc/kernel/pdc_chassis.c | |
1640 | ||
1641 | pf. [PARIDE] | |
1642 | See Documentation/paride.txt. | |
1643 | ||
1644 | pg. [PARIDE] | |
1645 | See Documentation/paride.txt. | |
1646 | ||
1647 | pirq= [SMP,APIC] Manual mp-table setup | |
1648 | See Documentation/i386/IO-APIC.txt. | |
1649 | ||
1650 | plip= [PPT,NET] Parallel port network link | |
1651 | Format: { parport<nr> | timid | 0 } | |
1652 | See also Documentation/parport.txt. | |
1653 | ||
de32a243 TG |
1654 | pmtmr= [X86] Manual setup of pmtmr I/O Port. |
1655 | Override pmtimer IOPort with a hex value. | |
1656 | e.g. pmtmr=0x508 | |
1657 | ||
1da177e4 LT |
1658 | pnpacpi= [ACPI] |
1659 | { off } | |
1660 | ||
1661 | pnpbios= [ISAPNP] | |
1662 | { on | off | curr | res | no-curr | no-res } | |
1663 | ||
1664 | pnp_reserve_irq= | |
1665 | [ISAPNP] Exclude IRQs for the autoconfiguration | |
1666 | ||
1667 | pnp_reserve_dma= | |
1668 | [ISAPNP] Exclude DMAs for the autoconfiguration | |
1669 | ||
1670 | pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration | |
a9913044 | 1671 | Ranges are in pairs (I/O port base and size). |
1da177e4 LT |
1672 | |
1673 | pnp_reserve_mem= | |
a9913044 RD |
1674 | [ISAPNP] Exclude memory regions for the |
1675 | autoconfiguration. | |
1da177e4 LT |
1676 | Ranges are in pairs (memory base and size). |
1677 | ||
45807a1d IM |
1678 | print-fatal-signals= |
1679 | [KNL] debug: print fatal signals | |
1680 | print-fatal-signals=1: print segfault info to | |
1681 | the kernel console. | |
1682 | default: off. | |
1683 | ||
e84845c4 RD |
1684 | printk.time= Show timing data prefixed to each printk message line |
1685 | Format: <bool> (1/Y/y=enable, 0/N/n=disable) | |
1686 | ||
1da177e4 | 1687 | profile= [KNL] Enable kernel profiling via /proc/profile |
a9913044 RD |
1688 | Format: [schedule,]<number> |
1689 | Param: "schedule" - profile schedule points. | |
1690 | Param: <number> - step/bucket size as a power of 2 for | |
1691 | statistical time based profiling. | |
b3da2a73 MG |
1692 | Param: "sleep" - profile D-state sleeping (millisecs). |
1693 | Requires CONFIG_SCHEDSTATS | |
c0fe2e69 | 1694 | Param: "kvm" - profile VM exits. |
1da177e4 | 1695 | |
a9913044 | 1696 | processor.max_cstate= [HW,ACPI] |
1da177e4 LT |
1697 | Limit processor to maximum C-state |
1698 | max_cstate=9 overrides any DMI blacklist limit. | |
1699 | ||
41c0d868 LB |
1700 | processor.nocst [HW,ACPI] |
1701 | Ignore the _CST method to determine C-states, | |
1702 | instead using the legacy FADT method | |
1703 | ||
1da177e4 LT |
1704 | prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk |
1705 | before loading. | |
1706 | See Documentation/ramdisk.txt. | |
1707 | ||
a9913044 RD |
1708 | psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to |
1709 | probe for; one of (bare|imps|exps|lifebook|any). | |
1da177e4 LT |
1710 | psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports |
1711 | per second. | |
a9913044 RD |
1712 | psmouse.resetafter= [HW,MOUSE] |
1713 | Try to reset the device after so many bad packets | |
1da177e4 LT |
1714 | (0 = never). |
1715 | psmouse.resolution= | |
1716 | [HW,MOUSE] Set desired mouse resolution, in dpi. | |
1717 | psmouse.smartscroll= | |
a9913044 | 1718 | [HW,MOUSE] Controls Logitech smartscroll autorepeat. |
1da177e4 LT |
1719 | 0 = disabled, 1 = enabled (default). |
1720 | ||
1721 | pss= [HW,OSS] Personal Sound System (ECHO ESC614) | |
a9913044 RD |
1722 | Format: |
1723 | <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq> | |
1da177e4 LT |
1724 | |
1725 | pt. [PARIDE] | |
1726 | See Documentation/paride.txt. | |
1727 | ||
dc8c8587 KS |
1728 | pty.legacy_count= |
1729 | [KNL] Number of legacy pty's. Overwrites compiled-in | |
1730 | default number. | |
1731 | ||
7d2c502f | 1732 | quiet [KNL] Disable most log messages |
a9913044 | 1733 | |
1da177e4 LT |
1734 | r128= [HW,DRM] |
1735 | ||
1736 | raid= [HW,RAID] | |
1737 | See Documentation/md.txt. | |
1738 | ||
a9913044 | 1739 | ramdisk_blocksize= [RAM] |
1da177e4 | 1740 | See Documentation/ramdisk.txt. |
a9913044 | 1741 | |
1da177e4 | 1742 | ramdisk_size= [RAM] Sizes of RAM disks in kilobytes |
1da177e4 LT |
1743 | See Documentation/ramdisk.txt. |
1744 | ||
24aaef8d RD |
1745 | rcupdate.blimit= [KNL,BOOT] |
1746 | Set maximum number of finished RCU callbacks to process | |
1747 | in one batch. | |
21a1ea9e | 1748 | |
24aaef8d RD |
1749 | rcupdate.qhimark= [KNL,BOOT] |
1750 | Set threshold of queued | |
21a1ea9e DS |
1751 | RCU callbacks over which batch limiting is disabled. |
1752 | ||
24aaef8d RD |
1753 | rcupdate.qlowmark= [KNL,BOOT] |
1754 | Set threshold of queued RCU callbacks below which | |
1755 | batch limiting is re-enabled. | |
21a1ea9e | 1756 | |
ffdfc409 OJ |
1757 | rdinit= [KNL] |
1758 | Format: <full_path> | |
1759 | Run specified binary instead of /init from the ramdisk, | |
1760 | used for early userspace startup. See initrd. | |
1761 | ||
cd4f0ef7 | 1762 | reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode |
1da177e4 | 1763 | Format: <reboot_mode>[,<reboot_mode2>[,...]] |
e53dd083 | 1764 | See arch/*/kernel/reboot.c or arch/*/kernel/process.c |
1da177e4 | 1765 | |
46b6d94e PJ |
1766 | relax_domain_level= |
1767 | [KNL, SMP] Set scheduler's default relax_domain_level. | |
1768 | See Documentation/cpusets.txt. | |
1769 | ||
1da177e4 LT |
1770 | reserve= [KNL,BUGS] Force the kernel to ignore some iomem area |
1771 | ||
cd4f0ef7 | 1772 | reservetop= [X86-32] |
461a9aff ZA |
1773 | Format: nn[KMG] |
1774 | Reserves a hole at the top of the kernel virtual | |
1775 | address space. | |
1776 | ||
7e96287d VG |
1777 | reset_devices [KNL] Force drivers to reset the underlying device |
1778 | during initialization. | |
1779 | ||
a9913044 RD |
1780 | resume= [SWSUSP] |
1781 | Specify the partition device for software suspend | |
1da177e4 | 1782 | |
ecbd0da1 RW |
1783 | resume_offset= [SWSUSP] |
1784 | Specify the offset from the beginning of the partition | |
1785 | given by "resume=" at which the swap header is located, | |
1786 | in <PAGE_SIZE> units (needed only for swap files). | |
1787 | See Documentation/power/swsusp-and-swap-files.txt | |
1788 | ||
0a7b35cb MN |
1789 | retain_initrd [RAM] Keep initrd memory after extraction |
1790 | ||
1da177e4 LT |
1791 | rhash_entries= [KNL,NET] |
1792 | Set number of hash buckets for route cache | |
1793 | ||
1794 | riscom8= [HW,SERIAL] | |
1795 | Format: <io_board1>[,<io_board2>[,...<io_boardN>]] | |
1796 | ||
1797 | ro [KNL] Mount root device read-only on boot | |
1798 | ||
1799 | root= [KNL] Root filesystem | |
1800 | ||
1801 | rootdelay= [KNL] Delay (in seconds) to pause before attempting to | |
1802 | mount the root filesystem | |
1803 | ||
1804 | rootflags= [KNL] Set root filesystem mount option string | |
1805 | ||
1806 | rootfstype= [KNL] Set root filesystem type | |
1807 | ||
cc1ed754 PO |
1808 | rootwait [KNL] Wait (indefinitely) for root device to show up. |
1809 | Useful for devices that are detected asynchronously | |
1810 | (e.g. USB and MMC devices). | |
1811 | ||
20510f2f JM |
1812 | root_plug.vendor_id= |
1813 | [ROOTPLUG] Override the default vendor ID | |
1814 | ||
1815 | root_plug.product_id= | |
1816 | [ROOTPLUG] Override the default product ID | |
1817 | ||
1818 | root_plug.debug= | |
1819 | [ROOTPLUG] Enable debugging output | |
1820 | ||
1da177e4 LT |
1821 | rw [KNL] Mount root device read-write on boot |
1822 | ||
1823 | S [KNL] Run init in single mode | |
1824 | ||
1825 | sa1100ir [NET] | |
1826 | See drivers/net/irda/sa1100_ir.c. | |
1827 | ||
1da177e4 | 1828 | sbni= [NET] Granch SBNI12 leased line adapter |
a9913044 | 1829 | |
1da177e4 LT |
1830 | sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver |
1831 | Format: <io>[,<timeout>[,<isapnp>]] | |
1832 | ||
1833 | scsi_debug_*= [SCSI] | |
1834 | See drivers/scsi/scsi_debug.c. | |
1835 | ||
1836 | scsi_default_dev_flags= | |
1837 | [SCSI] SCSI default device flags | |
1838 | Format: <integer> | |
1839 | ||
1840 | scsi_dev_flags= [SCSI] Black/white list entry for vendor and model | |
1841 | Format: <vendor>:<model>:<flags> | |
1842 | (flags are integer value) | |
1843 | ||
6af6632a RD |
1844 | scsi_logging_level= [SCSI] a bit mask of logging levels |
1845 | See drivers/scsi/scsi_logging.h for bits. Also | |
1846 | settable via sysctl at dev.scsi.logging_level | |
1847 | (/proc/sys/dev/scsi/logging_level). | |
1848 | There is also a nice 'scsi_logging_level' script in the | |
1849 | S390-tools package, available for download at | |
1850 | http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html | |
1da177e4 | 1851 | |
3e082a91 MW |
1852 | scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are |
1853 | discovered. async scans them in kernel threads, | |
1854 | allowing boot to proceed. none ignores them, expecting | |
1855 | user space to do the scan. | |
1856 | ||
1da177e4 LT |
1857 | selinux [SELINUX] Disable or enable SELinux at boot time. |
1858 | Format: { "0" | "1" } | |
1859 | See security/selinux/Kconfig help text. | |
1860 | 0 -- disable. | |
1861 | 1 -- enable. | |
1862 | Default value is set via kernel config option. | |
1863 | If enabled at boot time, /selinux/disable can be used | |
1864 | later to disable prior to initial policy load. | |
1865 | ||
4e5ab4cb JM |
1866 | selinux_compat_net = |
1867 | [SELINUX] Set initial selinux_compat_net flag value. | |
e53dd083 MCC |
1868 | Format: { "0" | "1" } |
1869 | 0 -- use new secmark-based packet controls | |
1870 | 1 -- use legacy packet controls | |
1871 | Default value is 0 (preferred). | |
1872 | Value can be changed at runtime via | |
1873 | /selinux/compat_net. | |
4e5ab4cb | 1874 | |
cd4f0ef7 | 1875 | serialnumber [BUGS=X86-32] |
1da177e4 | 1876 | |
1da177e4 LT |
1877 | shapers= [NET] |
1878 | Maximal number of shapers. | |
a9913044 | 1879 | |
1da177e4 LT |
1880 | sim710= [SCSI,HW] |
1881 | See header of drivers/scsi/sim710.c. | |
1882 | ||
1883 | simeth= [IA-64] | |
1884 | simscsi= | |
a9913044 | 1885 | |
1da177e4 LT |
1886 | slram= [HW,MTD] |
1887 | ||
f0630fff CL |
1888 | slub_debug[=options[,slabs]] [MM, SLUB] |
1889 | Enabling slub_debug allows one to determine the | |
1890 | culprit if slab objects become corrupted. Enabling | |
1891 | slub_debug can create guard zones around objects and | |
1892 | may poison objects when not in use. Also tracks the | |
1893 | last alloc / free. For more information see | |
1894 | Documentation/vm/slub.txt. | |
c1aee215 CL |
1895 | |
1896 | slub_max_order= [MM, SLUB] | |
f0630fff CL |
1897 | Determines the maximum allowed order for slabs. |
1898 | A high setting may cause OOMs due to memory | |
1899 | fragmentation. For more information see | |
1900 | Documentation/vm/slub.txt. | |
c1aee215 CL |
1901 | |
1902 | slub_min_objects= [MM, SLUB] | |
f0630fff CL |
1903 | The minimum number of objects per slab. SLUB will |
1904 | increase the slab order up to slub_max_order to | |
1905 | generate a sufficiently large slab able to contain | |
1906 | the number of objects indicated. The higher the number | |
1907 | of objects the smaller the overhead of tracking slabs | |
1908 | and the less frequently locks need to be acquired. | |
c1aee215 CL |
1909 | For more information see Documentation/vm/slub.txt. |
1910 | ||
1911 | slub_min_order= [MM, SLUB] | |
1912 | Determines the mininum page order for slabs. Must be | |
f0630fff | 1913 | lower than slub_max_order. |
c1aee215 CL |
1914 | For more information see Documentation/vm/slub.txt. |
1915 | ||
1916 | slub_nomerge [MM, SLUB] | |
f0630fff | 1917 | Disable merging of slabs with similar size. May be |
c1aee215 | 1918 | necessary if there is some reason to distinguish |
f0630fff CL |
1919 | allocs to different slabs. Debug options disable |
1920 | merging on their own. | |
c1aee215 CL |
1921 | For more information see Documentation/vm/slub.txt. |
1922 | ||
1da177e4 LT |
1923 | smart2= [HW] |
1924 | Format: <io1>[,<io2>[,...,<io8>]] | |
1925 | ||
cd4f0ef7 | 1926 | smp-alt-once [X86-32,SMP] On a hotplug CPU system, only |
b7fb4af0 JF |
1927 | attempt to substitute SMP alternatives once at boot. |
1928 | ||
d0d4f69b BH |
1929 | smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices |
1930 | smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port | |
1931 | smsc-ircc2.ircc_sir= [HW] SIR base I/O port | |
1932 | smsc-ircc2.ircc_fir= [HW] FIR base I/O port | |
1933 | smsc-ircc2.ircc_irq= [HW] IRQ line | |
1934 | smsc-ircc2.ircc_dma= [HW] DMA channel | |
1935 | smsc-ircc2.ircc_transceiver= [HW] Transceiver type: | |
1936 | 0: Toshiba Satellite 1800 (GP data pin select) | |
1937 | 1: Fast pin select (default) | |
1938 | 2: ATC IRMode | |
1939 | ||
1da177e4 LT |
1940 | snd-ad1816a= [HW,ALSA] |
1941 | ||
1942 | snd-ad1848= [HW,ALSA] | |
1943 | ||
1944 | snd-ali5451= [HW,ALSA] | |
1945 | ||
1946 | snd-als100= [HW,ALSA] | |
1947 | ||
1948 | snd-als4000= [HW,ALSA] | |
1949 | ||
1950 | snd-azt2320= [HW,ALSA] | |
1951 | ||
1952 | snd-cmi8330= [HW,ALSA] | |
1953 | ||
1954 | snd-cmipci= [HW,ALSA] | |
1955 | ||
1956 | snd-cs4231= [HW,ALSA] | |
1957 | ||
1958 | snd-cs4232= [HW,ALSA] | |
1959 | ||
1960 | snd-cs4236= [HW,ALSA] | |
1961 | ||
1962 | snd-cs4281= [HW,ALSA] | |
1963 | ||
1964 | snd-cs46xx= [HW,ALSA] | |
1965 | ||
1966 | snd-dt019x= [HW,ALSA] | |
1967 | ||
1968 | snd-dummy= [HW,ALSA] | |
1969 | ||
1970 | snd-emu10k1= [HW,ALSA] | |
1971 | ||
1972 | snd-ens1370= [HW,ALSA] | |
1973 | ||
1974 | snd-ens1371= [HW,ALSA] | |
1975 | ||
1976 | snd-es968= [HW,ALSA] | |
1977 | ||
1978 | snd-es1688= [HW,ALSA] | |
1979 | ||
1980 | snd-es18xx= [HW,ALSA] | |
1981 | ||
1982 | snd-es1938= [HW,ALSA] | |
1983 | ||
1984 | snd-es1968= [HW,ALSA] | |
1985 | ||
1986 | snd-fm801= [HW,ALSA] | |
1987 | ||
1988 | snd-gusclassic= [HW,ALSA] | |
1989 | ||
1990 | snd-gusextreme= [HW,ALSA] | |
1991 | ||
1992 | snd-gusmax= [HW,ALSA] | |
1993 | ||
1994 | snd-hdsp= [HW,ALSA] | |
1995 | ||
1996 | snd-ice1712= [HW,ALSA] | |
1997 | ||
1998 | snd-intel8x0= [HW,ALSA] | |
1999 | ||
2000 | snd-interwave= [HW,ALSA] | |
2001 | ||
2002 | snd-interwave-stb= | |
2003 | [HW,ALSA] | |
2004 | ||
2005 | snd-korg1212= [HW,ALSA] | |
2006 | ||
2007 | snd-maestro3= [HW,ALSA] | |
2008 | ||
2009 | snd-mpu401= [HW,ALSA] | |
2010 | ||
2011 | snd-mtpav= [HW,ALSA] | |
2012 | ||
2013 | snd-nm256= [HW,ALSA] | |
2014 | ||
2015 | snd-opl3sa2= [HW,ALSA] | |
2016 | ||
2017 | snd-opti92x-ad1848= | |
2018 | [HW,ALSA] | |
2019 | ||
2020 | snd-opti92x-cs4231= | |
2021 | [HW,ALSA] | |
2022 | ||
2023 | snd-opti93x= [HW,ALSA] | |
2024 | ||
2025 | snd-pmac= [HW,ALSA] | |
2026 | ||
2027 | snd-rme32= [HW,ALSA] | |
2028 | ||
2029 | snd-rme96= [HW,ALSA] | |
2030 | ||
2031 | snd-rme9652= [HW,ALSA] | |
2032 | ||
2033 | snd-sb8= [HW,ALSA] | |
2034 | ||
2035 | snd-sb16= [HW,ALSA] | |
2036 | ||
2037 | snd-sbawe= [HW,ALSA] | |
2038 | ||
2039 | snd-serial= [HW,ALSA] | |
2040 | ||
2041 | snd-sgalaxy= [HW,ALSA] | |
2042 | ||
2043 | snd-sonicvibes= [HW,ALSA] | |
2044 | ||
2045 | snd-sun-amd7930= | |
2046 | [HW,ALSA] | |
2047 | ||
2048 | snd-sun-cs4231= [HW,ALSA] | |
2049 | ||
2050 | snd-trident= [HW,ALSA] | |
2051 | ||
2052 | snd-usb-audio= [HW,ALSA,USB] | |
2053 | ||
2054 | snd-via82xx= [HW,ALSA] | |
2055 | ||
2056 | snd-virmidi= [HW,ALSA] | |
2057 | ||
2058 | snd-wavefront= [HW,ALSA] | |
2059 | ||
2060 | snd-ymfpci= [HW,ALSA] | |
a9913044 | 2061 | |
9c44bc03 IM |
2062 | softlockup_panic= |
2063 | [KNL] Should the soft-lockup detector generate panics. | |
2064 | ||
1da177e4 LT |
2065 | sonypi.*= [HW] Sony Programmable I/O Control Device driver |
2066 | See Documentation/sonypi.txt | |
2067 | ||
2068 | specialix= [HW,SERIAL] Specialix multi-serial port adapter | |
2069 | See Documentation/specialix.txt. | |
2070 | ||
2071 | spia_io_base= [HW,MTD] | |
2072 | spia_fio_base= | |
2073 | spia_pedr= | |
2074 | spia_peddr= | |
2075 | ||
2076 | sscape= [HW,OSS] | |
2077 | Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq> | |
a9913044 | 2078 | |
1da177e4 LT |
2079 | st= [HW,SCSI] SCSI tape parameters (buffers, etc.) |
2080 | See Documentation/scsi/st.txt. | |
2081 | ||
1da177e4 LT |
2082 | sti= [PARISC,HW] |
2083 | Format: <num> | |
2084 | Set the STI (builtin display/keyboard on the HP-PARISC | |
2085 | machines) console (graphic card) which should be used | |
2086 | as the initial boot-console. | |
2087 | See also comment in drivers/video/console/sticore.c. | |
2088 | ||
2089 | sti_font= [HW] | |
2090 | See comment in drivers/video/console/sticore.c. | |
2091 | ||
2092 | stifb= [HW] | |
2093 | Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] | |
2094 | ||
42a7fc4a GB |
2095 | sunrpc.pool_mode= |
2096 | [NFS] | |
2097 | Control how the NFS server code allocates CPUs to | |
2098 | service thread pools. Depending on how many NICs | |
2099 | you have and where their interrupts are bound, this | |
2100 | option will affect which CPUs will do NFS serving. | |
2101 | Note: this parameter cannot be changed while the | |
2102 | NFS server is running. | |
2103 | ||
2104 | auto the server chooses an appropriate mode | |
2105 | automatically using heuristics | |
2106 | global a single global pool contains all CPUs | |
2107 | percpu one pool for each CPU | |
2108 | pernode one pool for each NUMA node (equivalent | |
2109 | to global on non-NUMA machines) | |
2110 | ||
1da177e4 | 2111 | swiotlb= [IA-64] Number of I/O TLB slabs |
a9913044 | 2112 | |
1da177e4 LT |
2113 | switches= [HW,M68k] |
2114 | ||
2115 | sym53c416= [HW,SCSI] | |
2116 | See header of drivers/scsi/sym53c416.c. | |
2117 | ||
5d6f647f IM |
2118 | sysrq_always_enabled |
2119 | [KNL] | |
2120 | Ignore sysrq setting - this boot parameter will | |
2121 | neutralize any effect of /proc/sys/kernel/sysrq. | |
2122 | Useful for debugging. | |
2123 | ||
1da177e4 LT |
2124 | t128= [HW,SCSI] |
2125 | See header of drivers/scsi/t128.c. | |
2126 | ||
2127 | tdfx= [HW,DRM] | |
2128 | ||
77437fd4 DB |
2129 | test_suspend= [SUSPEND] |
2130 | Specify "mem" (for Suspend-to-RAM) or "standby" (for | |
2131 | standby suspend) as the system sleep state to briefly | |
2132 | enter during system startup. The system is woken from | |
2133 | this state using a wakeup-capable RTC alarm. | |
2134 | ||
1da177e4 LT |
2135 | thash_entries= [KNL,NET] |
2136 | Set number of hash buckets for TCP connection | |
2137 | ||
f8707ec9 LB |
2138 | thermal.act= [HW,ACPI] |
2139 | -1: disable all active trip points in all thermal zones | |
2140 | <degrees C>: override all lowest active trip points | |
2141 | ||
c52a7419 LB |
2142 | thermal.crt= [HW,ACPI] |
2143 | -1: disable all critical trip points in all thermal zones | |
2144 | <degrees C>: lower all critical trip points | |
2145 | ||
f5487145 LB |
2146 | thermal.nocrt= [HW,ACPI] |
2147 | Set to disable actions on ACPI thermal zone | |
2148 | critical and hot trip points. | |
2149 | ||
72b33ef8 LB |
2150 | thermal.off= [HW,ACPI] |
2151 | 1: disable ACPI thermal control | |
2152 | ||
a70cdc52 LB |
2153 | thermal.psv= [HW,ACPI] |
2154 | -1: disable all passive trip points | |
2155 | <degrees C>: override all passive trip points to this value | |
2156 | ||
730ff34d LB |
2157 | thermal.tzp= [HW,ACPI] |
2158 | Specify global default ACPI thermal zone polling rate | |
2159 | <deci-seconds>: poll all this frequency | |
2160 | 0: no polling (default) | |
2161 | ||
1da177e4 LT |
2162 | tmscsim= [HW,SCSI] |
2163 | See comment before function dc390_setup() in | |
2164 | drivers/scsi/tmscsim.c. | |
2165 | ||
2166 | tp720= [HW,PS2] | |
2167 | ||
2168 | trix= [HW,OSS] MediaTrix AudioTrix Pro | |
a9913044 RD |
2169 | Format: |
2170 | <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq> | |
2171 | ||
a9913044 RD |
2172 | turbografx.map[2|3]= [HW,JOY] |
2173 | TurboGraFX parallel port interface | |
2174 | Format: | |
2175 | <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> | |
1da177e4 LT |
2176 | See also Documentation/input/joystick-parport.txt |
2177 | ||
2178 | u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter | |
2179 | See header of drivers/scsi/u14-34f.c. | |
2180 | ||
2181 | uart401= [HW,OSS] | |
2182 | Format: <io>,<irq> | |
2183 | ||
2184 | uart6850= [HW,OSS] | |
2185 | Format: <io>,<irq> | |
2186 | ||
5f8364b7 AS |
2187 | uhci-hcd.ignore_oc= |
2188 | [USB] Ignore overcurrent events (default N). | |
2189 | Some badly-designed motherboards generate lots of | |
2190 | bogus events, for ports that aren't wired to | |
2191 | anything. Set this parameter to avoid log spamming. | |
2192 | Note that genuine overcurrent events won't be | |
2193 | reported either. | |
2194 | ||
e3a61b0a SA |
2195 | unknown_nmi_panic |
2196 | [X86-32,X86-64] | |
2197 | Set unknown_nmi_panic=1 early on boot. | |
2198 | ||
b5e795f8 AS |
2199 | usbcore.autosuspend= |
2200 | [USB] The autosuspend time delay (in seconds) used | |
2201 | for newly-detected USB devices (default 2). This | |
2202 | is the time required before an idle device will be | |
2203 | autosuspended. Devices for which the delay is set | |
eaafbc3a | 2204 | to a negative value won't be autosuspended at all. |
b5e795f8 | 2205 | |
1da177e4 LT |
2206 | usbhid.mousepoll= |
2207 | [USBHID] The interval which mice are to be polled at. | |
a9913044 | 2208 | |
200001eb PJ |
2209 | add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in |
2210 | kernel's map of available physical RAM. | |
2211 | ||
cd4f0ef7 | 2212 | vdso= [X86-32,SH,x86-64] |
1dbf527c | 2213 | vdso=2: enable compat VDSO (default with COMPAT_VDSO) |
e6e5494c IM |
2214 | vdso=1: enable VDSO (default) |
2215 | vdso=0: disable VDSO mapping | |
2216 | ||
af65d648 RM |
2217 | vdso32= [X86-32,X86-64] |
2218 | vdso32=2: enable compat VDSO (default with COMPAT_VDSO) | |
2219 | vdso32=1: enable 32-bit VDSO (default) | |
2220 | vdso32=0: disable 32-bit VDSO mapping | |
2221 | ||
d080d397 YI |
2222 | vector= [IA-64,SMP] |
2223 | vector=percpu: enable percpu vector domain | |
2224 | ||
1da177e4 LT |
2225 | video= [FB] Frame buffer configuration |
2226 | See Documentation/fb/modedb.txt. | |
2227 | ||
cd4f0ef7 | 2228 | vga= [BOOT,X86-32] Select a particular video mode |
a9913044 RD |
2229 | See Documentation/i386/boot.txt and |
2230 | Documentation/svga.txt. | |
1da177e4 LT |
2231 | Use vga=ask for menu. |
2232 | This is actually a boot loader parameter; the value is | |
2233 | passed to the kernel using a special protocol. | |
2234 | ||
a9913044 | 2235 | vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact |
1da177e4 LT |
2236 | size of <nn>. This can be used to increase the |
2237 | minimum size (128MB on x86). It can also be used to | |
2238 | decrease the size and leave more room for directly | |
2239 | mapped kernel RAM. | |
2240 | ||
585c3047 PO |
2241 | vmhalt= [KNL,S390] Perform z/VM CP command after system halt. |
2242 | Format: <command> | |
1da177e4 | 2243 | |
585c3047 PO |
2244 | vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. |
2245 | Format: <command> | |
2246 | ||
2247 | vmpoff= [KNL,S390] Perform z/VM CP command after power off. | |
2248 | Format: <command> | |
a9913044 | 2249 | |
1da177e4 LT |
2250 | waveartist= [HW,OSS] |
2251 | Format: <io>,<irq>,<dma>,<dma2> | |
a9913044 | 2252 | |
1da177e4 LT |
2253 | wd33c93= [HW,SCSI] |
2254 | See header of drivers/scsi/wd33c93.c. | |
2255 | ||
2256 | wd7000= [HW,SCSI] | |
2257 | See header of drivers/scsi/wd7000.c. | |
2258 | ||
2259 | wdt= [WDT] Watchdog | |
8dfe9c21 | 2260 | See Documentation/watchdog/wdt.txt. |
1da177e4 LT |
2261 | |
2262 | xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. | |
2263 | xd_geo= See header of drivers/block/xd.c. | |
2264 | ||
2265 | xirc2ps_cs= [NET,PCMCIA] | |
a9913044 RD |
2266 | Format: |
2267 | <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] | |
1da177e4 | 2268 | |
a62eaf15 AK |
2269 | norandmaps Don't use address space randomization |
2270 | Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space | |
2271 | ||
a9913044 | 2272 | ______________________________________________________________________ |
1da177e4 LT |
2273 | |
2274 | TODO: | |
2275 | ||
2276 | Add documentation for ALSA options. | |
2277 | Add more DRM drivers. |