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Commit | Line | Data |
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1 | Kernel Parameters | |
2 | ~~~~~~~~~~~~~~~~~ | |
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 | ||
20 | Hyphens (dashes) and underscores are equivalent in parameter names, so | |
21 | log_buf_len=1M print-fatal-signals=1 | |
22 | can also be entered as | |
23 | log-buf-len=1M print_fatal_signals=1 | |
24 | ||
25 | ||
26 | This document may not be entirely up to date and comprehensive. The command | |
27 | "modinfo -p ${modulename}" shows a current list of all parameters of a loadable | |
28 | module. Loadable modules, after being loaded into the running kernel, also | |
29 | reveal their parameters in /sys/module/${modulename}/parameters/. Some of these | |
30 | parameters may be changed at runtime by the command | |
31 | "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}". | |
32 | ||
33 | The parameters listed below are only valid if certain kernel build options were | |
34 | enabled and if respective hardware is present. The text in square brackets at | |
35 | the beginning of each description states the restrictions within which a | |
36 | parameter is applicable: | |
37 | ||
38 | ACPI ACPI support is enabled. | |
39 | AGP AGP (Accelerated Graphics Port) is enabled. | |
40 | ALSA ALSA sound support is enabled. | |
41 | APIC APIC support is enabled. | |
42 | APM Advanced Power Management support is enabled. | |
43 | ARM ARM architecture is enabled. | |
44 | AVR32 AVR32 architecture is enabled. | |
45 | AX25 Appropriate AX.25 support is enabled. | |
46 | BLACKFIN Blackfin architecture is enabled. | |
47 | CLK Common clock infrastructure is enabled. | |
48 | CMA Contiguous Memory Area support is enabled. | |
49 | DRM Direct Rendering Management support is enabled. | |
50 | DYNAMIC_DEBUG Build in debug messages and enable them at runtime | |
51 | EDD BIOS Enhanced Disk Drive Services (EDD) is enabled | |
52 | EFI EFI Partitioning (GPT) is enabled | |
53 | EIDE EIDE/ATAPI support is enabled. | |
54 | EVM Extended Verification Module | |
55 | FB The frame buffer device is enabled. | |
56 | FTRACE Function tracing enabled. | |
57 | GCOV GCOV profiling is enabled. | |
58 | HW Appropriate hardware is enabled. | |
59 | IA-64 IA-64 architecture is enabled. | |
60 | IMA Integrity measurement architecture is enabled. | |
61 | IOSCHED More than one I/O scheduler is enabled. | |
62 | IP_PNP IP DHCP, BOOTP, or RARP is enabled. | |
63 | IPV6 IPv6 support is enabled. | |
64 | ISAPNP ISA PnP code is enabled. | |
65 | ISDN Appropriate ISDN support is enabled. | |
66 | JOY Appropriate joystick support is enabled. | |
67 | KGDB Kernel debugger support is enabled. | |
68 | KVM Kernel Virtual Machine support is enabled. | |
69 | LIBATA Libata driver is enabled | |
70 | LP Printer support is enabled. | |
71 | LOOP Loopback device support is enabled. | |
72 | M68k M68k architecture is enabled. | |
73 | These options have more detailed description inside of | |
74 | Documentation/m68k/kernel-options.txt. | |
75 | MDA MDA console support is enabled. | |
76 | MIPS MIPS architecture is enabled. | |
77 | MOUSE Appropriate mouse support is enabled. | |
78 | MSI Message Signaled Interrupts (PCI). | |
79 | MTD MTD (Memory Technology Device) support is enabled. | |
80 | NET Appropriate network support is enabled. | |
81 | NUMA NUMA support is enabled. | |
82 | NFS Appropriate NFS support is enabled. | |
83 | OSS OSS sound support is enabled. | |
84 | PV_OPS A paravirtualized kernel is enabled. | |
85 | PARIDE The ParIDE (parallel port IDE) subsystem is enabled. | |
86 | PARISC The PA-RISC architecture is enabled. | |
87 | PCI PCI bus support is enabled. | |
88 | PCIE PCI Express support is enabled. | |
89 | PCMCIA The PCMCIA subsystem is enabled. | |
90 | PNP Plug & Play support is enabled. | |
91 | PPC PowerPC architecture is enabled. | |
92 | PPT Parallel port support is enabled. | |
93 | PS2 Appropriate PS/2 support is enabled. | |
94 | RAM RAM disk support is enabled. | |
95 | S390 S390 architecture is enabled. | |
96 | SCSI Appropriate SCSI support is enabled. | |
97 | A lot of drivers have their options described inside | |
98 | the Documentation/scsi/ sub-directory. | |
99 | SECURITY Different security models are enabled. | |
100 | SELINUX SELinux support is enabled. | |
101 | APPARMOR AppArmor support is enabled. | |
102 | SERIAL Serial support is enabled. | |
103 | SH SuperH architecture is enabled. | |
104 | SMP The kernel is an SMP kernel. | |
105 | SPARC Sparc architecture is enabled. | |
106 | SWSUSP Software suspend (hibernation) is enabled. | |
107 | SUSPEND System suspend states are enabled. | |
108 | TPM TPM drivers are enabled. | |
109 | TS Appropriate touchscreen support is enabled. | |
110 | UMS USB Mass Storage support is enabled. | |
111 | USB USB support is enabled. | |
112 | USBHID USB Human Interface Device support is enabled. | |
113 | V4L Video For Linux support is enabled. | |
114 | VMMIO Driver for memory mapped virtio devices is enabled. | |
115 | VGA The VGA console has been enabled. | |
116 | VT Virtual terminal support is enabled. | |
117 | WDT Watchdog support is enabled. | |
118 | XT IBM PC/XT MFM hard disk support is enabled. | |
119 | X86-32 X86-32, aka i386 architecture is enabled. | |
120 | X86-64 X86-64 architecture is enabled. | |
121 | More X86-64 boot options can be found in | |
122 | Documentation/x86/x86_64/boot-options.txt . | |
123 | X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64) | |
124 | XEN Xen support is enabled | |
125 | ||
126 | In addition, the following text indicates that the option: | |
127 | ||
128 | BUGS= Relates to possible processor bugs on the said processor. | |
129 | KNL Is a kernel start-up parameter. | |
130 | BOOT Is a boot loader parameter. | |
131 | ||
132 | Parameters denoted with BOOT are actually interpreted by the boot | |
133 | loader, and have no meaning to the kernel directly. | |
134 | Do not modify the syntax of boot loader parameters without extreme | |
135 | need or coordination with <Documentation/x86/boot.txt>. | |
136 | ||
137 | There are also arch-specific kernel-parameters not documented here. | |
138 | See for example <Documentation/x86/x86_64/boot-options.txt>. | |
139 | ||
140 | Note that ALL kernel parameters listed below are CASE SENSITIVE, and that | |
141 | a trailing = on the name of any parameter states that that parameter will | |
142 | be entered as an environment variable, whereas its absence indicates that | |
143 | it will appear as a kernel argument readable via /proc/cmdline by programs | |
144 | running once the system is up. | |
145 | ||
146 | The number of kernel parameters is not limited, but the length of the | |
147 | complete command line (parameters including spaces etc.) is limited to | |
148 | a fixed number of characters. This limit depends on the architecture | |
149 | and is between 256 and 4096 characters. It is defined in the file | |
150 | ./include/asm/setup.h as COMMAND_LINE_SIZE. | |
151 | ||
152 | Finally, the [KMG] suffix is commonly described after a number of kernel | |
153 | parameter values. These 'K', 'M', and 'G' letters represent the _binary_ | |
154 | multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30 | |
155 | bytes respectively. Such letter suffixes can also be entirely omitted. | |
156 | ||
157 | ||
158 | acpi= [HW,ACPI,X86] | |
159 | Advanced Configuration and Power Interface | |
160 | Format: { force | off | strict | noirq | rsdt } | |
161 | force -- enable ACPI if default was off | |
162 | off -- disable ACPI if default was on | |
163 | noirq -- do not use ACPI for IRQ routing | |
164 | strict -- Be less tolerant of platforms that are not | |
165 | strictly ACPI specification compliant. | |
166 | rsdt -- prefer RSDT over (default) XSDT | |
167 | copy_dsdt -- copy DSDT to memory | |
168 | ||
169 | See also Documentation/power/runtime_pm.txt, pci=noacpi | |
170 | ||
171 | acpi_rsdp= [ACPI,EFI,KEXEC] | |
172 | Pass the RSDP address to the kernel, mostly used | |
173 | on machines running EFI runtime service to boot the | |
174 | second kernel for kdump. | |
175 | ||
176 | acpi_apic_instance= [ACPI, IOAPIC] | |
177 | Format: <int> | |
178 | 2: use 2nd APIC table, if available | |
179 | 1,0: use 1st APIC table | |
180 | default: 0 | |
181 | ||
182 | acpi_backlight= [HW,ACPI] | |
183 | acpi_backlight=vendor | |
184 | acpi_backlight=video | |
185 | If set to vendor, prefer vendor specific driver | |
186 | (e.g. thinkpad_acpi, sony_acpi, etc.) instead | |
187 | of the ACPI video.ko driver. | |
188 | ||
189 | acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] | |
190 | acpi.debug_level= [HW,ACPI,ACPI_DEBUG] | |
191 | Format: <int> | |
192 | CONFIG_ACPI_DEBUG must be enabled to produce any ACPI | |
193 | debug output. Bits in debug_layer correspond to a | |
194 | _COMPONENT in an ACPI source file, e.g., | |
195 | #define _COMPONENT ACPI_PCI_COMPONENT | |
196 | Bits in debug_level correspond to a level in | |
197 | ACPI_DEBUG_PRINT statements, e.g., | |
198 | ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... | |
199 | The debug_level mask defaults to "info". See | |
200 | Documentation/acpi/debug.txt for more information about | |
201 | debug layers and levels. | |
202 | ||
203 | Enable processor driver info messages: | |
204 | acpi.debug_layer=0x20000000 | |
205 | Enable PCI/PCI interrupt routing info messages: | |
206 | acpi.debug_layer=0x400000 | |
207 | Enable AML "Debug" output, i.e., stores to the Debug | |
208 | object while interpreting AML: | |
209 | acpi.debug_layer=0xffffffff acpi.debug_level=0x2 | |
210 | Enable all messages related to ACPI hardware: | |
211 | acpi.debug_layer=0x2 acpi.debug_level=0xffffffff | |
212 | ||
213 | Some values produce so much output that the system is | |
214 | unusable. The "log_buf_len" parameter may be useful | |
215 | if you need to capture more output. | |
216 | ||
217 | acpi_irq_balance [HW,ACPI] | |
218 | ACPI will balance active IRQs | |
219 | default in APIC mode | |
220 | ||
221 | acpi_irq_nobalance [HW,ACPI] | |
222 | ACPI will not move active IRQs (default) | |
223 | default in PIC mode | |
224 | ||
225 | acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA | |
226 | Format: <irq>,<irq>... | |
227 | ||
228 | acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for | |
229 | use by PCI | |
230 | Format: <irq>,<irq>... | |
231 | ||
232 | acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT | |
233 | ||
234 | acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS | |
235 | Format: To spoof as Windows 98: ="Microsoft Windows" | |
236 | ||
237 | acpi_osi= [HW,ACPI] Modify list of supported OS interface strings | |
238 | acpi_osi="string1" # add string1 | |
239 | acpi_osi="!string2" # remove string2 | |
240 | acpi_osi=!* # remove all strings | |
241 | acpi_osi=! # disable all built-in OS vendor | |
242 | strings | |
243 | acpi_osi= # disable all strings | |
244 | ||
245 | 'acpi_osi=!' can be used in combination with single or | |
246 | multiple 'acpi_osi="string1"' to support specific OS | |
247 | vendor string(s). Note that such command can only | |
248 | affect the default state of the OS vendor strings, thus | |
249 | it cannot affect the default state of the feature group | |
250 | strings and the current state of the OS vendor strings, | |
251 | specifying it multiple times through kernel command line | |
252 | is meaningless. This command is useful when one do not | |
253 | care about the state of the feature group strings which | |
254 | should be controlled by the OSPM. | |
255 | Examples: | |
256 | 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent | |
257 | to 'acpi_osi="Windows 2000" acpi_osi=!', they all | |
258 | can make '_OSI("Windows 2000")' TRUE. | |
259 | ||
260 | 'acpi_osi=' cannot be used in combination with other | |
261 | 'acpi_osi=' command lines, the _OSI method will not | |
262 | exist in the ACPI namespace. NOTE that such command can | |
263 | only affect the _OSI support state, thus specifying it | |
264 | multiple times through kernel command line is also | |
265 | meaningless. | |
266 | Examples: | |
267 | 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' | |
268 | FALSE. | |
269 | ||
270 | 'acpi_osi=!*' can be used in combination with single or | |
271 | multiple 'acpi_osi="string1"' to support specific | |
272 | string(s). Note that such command can affect the | |
273 | current state of both the OS vendor strings and the | |
274 | feature group strings, thus specifying it multiple times | |
275 | through kernel command line is meaningful. But it may | |
276 | still not able to affect the final state of a string if | |
277 | there are quirks related to this string. This command | |
278 | is useful when one want to control the state of the | |
279 | feature group strings to debug BIOS issues related to | |
280 | the OSPM features. | |
281 | Examples: | |
282 | 1. 'acpi_osi="Module Device" acpi_osi=!*' can make | |
283 | '_OSI("Module Device")' FALSE. | |
284 | 2. 'acpi_osi=!* acpi_osi="Module Device"' can make | |
285 | '_OSI("Module Device")' TRUE. | |
286 | 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is | |
287 | equivalent to | |
288 | 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' | |
289 | and | |
290 | 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', | |
291 | they all will make '_OSI("Windows 2000")' TRUE. | |
292 | ||
293 | acpi_pm_good [X86] | |
294 | Override the pmtimer bug detection: force the kernel | |
295 | to assume that this machine's pmtimer latches its value | |
296 | and always returns good values. | |
297 | ||
298 | acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode | |
299 | Format: { level | edge | high | low } | |
300 | ||
301 | acpi_serialize [HW,ACPI] force serialization of AML methods | |
302 | ||
303 | acpi_skip_timer_override [HW,ACPI] | |
304 | Recognize and ignore IRQ0/pin2 Interrupt Override. | |
305 | For broken nForce2 BIOS resulting in XT-PIC timer. | |
306 | ||
307 | acpi_sleep= [HW,ACPI] Sleep options | |
308 | Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, | |
309 | old_ordering, nonvs, sci_force_enable } | |
310 | See Documentation/power/video.txt for information on | |
311 | s3_bios and s3_mode. | |
312 | s3_beep is for debugging; it makes the PC's speaker beep | |
313 | as soon as the kernel's real-mode entry point is called. | |
314 | s4_nohwsig prevents ACPI hardware signature from being | |
315 | used during resume from hibernation. | |
316 | old_ordering causes the ACPI 1.0 ordering of the _PTS | |
317 | control method, with respect to putting devices into | |
318 | low power states, to be enforced (the ACPI 2.0 ordering | |
319 | of _PTS is used by default). | |
320 | nonvs prevents the kernel from saving/restoring the | |
321 | ACPI NVS memory during suspend/hibernation and resume. | |
322 | sci_force_enable causes the kernel to set SCI_EN directly | |
323 | on resume from S1/S3 (which is against the ACPI spec, | |
324 | but some broken systems don't work without it). | |
325 | ||
326 | acpi_use_timer_override [HW,ACPI] | |
327 | Use timer override. For some broken Nvidia NF5 boards | |
328 | that require a timer override, but don't have HPET | |
329 | ||
330 | acpi_enforce_resources= [ACPI] | |
331 | { strict | lax | no } | |
332 | Check for resource conflicts between native drivers | |
333 | and ACPI OperationRegions (SystemIO and SystemMemory | |
334 | only). IO ports and memory declared in ACPI might be | |
335 | used by the ACPI subsystem in arbitrary AML code and | |
336 | can interfere with legacy drivers. | |
337 | strict (default): access to resources claimed by ACPI | |
338 | is denied; legacy drivers trying to access reserved | |
339 | resources will fail to bind to device using them. | |
340 | lax: access to resources claimed by ACPI is allowed; | |
341 | legacy drivers trying to access reserved resources | |
342 | will bind successfully but a warning message is logged. | |
343 | no: ACPI OperationRegions are not marked as reserved, | |
344 | no further checks are performed. | |
345 | ||
346 | add_efi_memmap [EFI; X86] Include EFI memory map in | |
347 | kernel's map of available physical RAM. | |
348 | ||
349 | agp= [AGP] | |
350 | { off | try_unsupported } | |
351 | off: disable AGP support | |
352 | try_unsupported: try to drive unsupported chipsets | |
353 | (may crash computer or cause data corruption) | |
354 | ||
355 | ALSA [HW,ALSA] | |
356 | See Documentation/sound/alsa/alsa-parameters.txt | |
357 | ||
358 | alignment= [KNL,ARM] | |
359 | Allow the default userspace alignment fault handler | |
360 | behaviour to be specified. Bit 0 enables warnings, | |
361 | bit 1 enables fixups, and bit 2 sends a segfault. | |
362 | ||
363 | align_va_addr= [X86-64] | |
364 | Align virtual addresses by clearing slice [14:12] when | |
365 | allocating a VMA at process creation time. This option | |
366 | gives you up to 3% performance improvement on AMD F15h | |
367 | machines (where it is enabled by default) for a | |
368 | CPU-intensive style benchmark, and it can vary highly in | |
369 | a microbenchmark depending on workload and compiler. | |
370 | ||
371 | 32: only for 32-bit processes | |
372 | 64: only for 64-bit processes | |
373 | on: enable for both 32- and 64-bit processes | |
374 | off: disable for both 32- and 64-bit processes | |
375 | ||
376 | alloc_snapshot [FTRACE] | |
377 | Allocate the ftrace snapshot buffer on boot up when the | |
378 | main buffer is allocated. This is handy if debugging | |
379 | and you need to use tracing_snapshot() on boot up, and | |
380 | do not want to use tracing_snapshot_alloc() as it needs | |
381 | to be done where GFP_KERNEL allocations are allowed. | |
382 | ||
383 | amd_iommu= [HW,X86-64] | |
384 | Pass parameters to the AMD IOMMU driver in the system. | |
385 | Possible values are: | |
386 | fullflush - enable flushing of IO/TLB entries when | |
387 | they are unmapped. Otherwise they are | |
388 | flushed before they will be reused, which | |
389 | is a lot of faster | |
390 | off - do not initialize any AMD IOMMU found in | |
391 | the system | |
392 | force_isolation - Force device isolation for all | |
393 | devices. The IOMMU driver is not | |
394 | allowed anymore to lift isolation | |
395 | requirements as needed. This option | |
396 | does not override iommu=pt | |
397 | ||
398 | amd_iommu_dump= [HW,X86-64] | |
399 | Enable AMD IOMMU driver option to dump the ACPI table | |
400 | for AMD IOMMU. With this option enabled, AMD IOMMU | |
401 | driver will print ACPI tables for AMD IOMMU during | |
402 | IOMMU initialization. | |
403 | ||
404 | amijoy.map= [HW,JOY] Amiga joystick support | |
405 | Map of devices attached to JOY0DAT and JOY1DAT | |
406 | Format: <a>,<b> | |
407 | See also Documentation/input/joystick.txt | |
408 | ||
409 | analog.map= [HW,JOY] Analog joystick and gamepad support | |
410 | Specifies type or capabilities of an analog joystick | |
411 | connected to one of 16 gameports | |
412 | Format: <type1>,<type2>,..<type16> | |
413 | ||
414 | apc= [HW,SPARC] | |
415 | Power management functions (SPARCstation-4/5 + deriv.) | |
416 | Format: noidle | |
417 | Disable APC CPU standby support. SPARCstation-Fox does | |
418 | not play well with APC CPU idle - disable it if you have | |
419 | APC and your system crashes randomly. | |
420 | ||
421 | apic= [APIC,X86-32] Advanced Programmable Interrupt Controller | |
422 | Change the output verbosity whilst booting | |
423 | Format: { quiet (default) | verbose | debug } | |
424 | Change the amount of debugging information output | |
425 | when initialising the APIC and IO-APIC components. | |
426 | ||
427 | autoconf= [IPV6] | |
428 | See Documentation/networking/ipv6.txt. | |
429 | ||
430 | show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller | |
431 | Limit apic dumping. The parameter defines the maximal | |
432 | number of local apics being dumped. Also it is possible | |
433 | to set it to "all" by meaning -- no limit here. | |
434 | Format: { 1 (default) | 2 | ... | all }. | |
435 | The parameter valid if only apic=debug or | |
436 | apic=verbose is specified. | |
437 | Example: apic=debug show_lapic=all | |
438 | ||
439 | apm= [APM] Advanced Power Management | |
440 | See header of arch/x86/kernel/apm_32.c. | |
441 | ||
442 | arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards | |
443 | Format: <io>,<irq>,<nodeID> | |
444 | ||
445 | ataflop= [HW,M68k] | |
446 | ||
447 | atarimouse= [HW,MOUSE] Atari Mouse | |
448 | ||
449 | atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, | |
450 | EzKey and similar keyboards | |
451 | ||
452 | atkbd.reset= [HW] Reset keyboard during initialization | |
453 | ||
454 | atkbd.set= [HW] Select keyboard code set | |
455 | Format: <int> (2 = AT (default), 3 = PS/2) | |
456 | ||
457 | atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar | |
458 | keyboards | |
459 | ||
460 | atkbd.softraw= [HW] Choose between synthetic and real raw mode | |
461 | Format: <bool> (0 = real, 1 = synthetic (default)) | |
462 | ||
463 | atkbd.softrepeat= [HW] | |
464 | Use software keyboard repeat | |
465 | ||
466 | baycom_epp= [HW,AX25] | |
467 | Format: <io>,<mode> | |
468 | ||
469 | baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem | |
470 | Format: <io>,<mode> | |
471 | See header of drivers/net/hamradio/baycom_par.c. | |
472 | ||
473 | baycom_ser_fdx= [HW,AX25] | |
474 | BayCom Serial Port AX.25 Modem (Full Duplex Mode) | |
475 | Format: <io>,<irq>,<mode>[,<baud>] | |
476 | See header of drivers/net/hamradio/baycom_ser_fdx.c. | |
477 | ||
478 | baycom_ser_hdx= [HW,AX25] | |
479 | BayCom Serial Port AX.25 Modem (Half Duplex Mode) | |
480 | Format: <io>,<irq>,<mode> | |
481 | See header of drivers/net/hamradio/baycom_ser_hdx.c. | |
482 | ||
483 | boot_delay= Milliseconds to delay each printk during boot. | |
484 | Values larger than 10 seconds (10000) are changed to | |
485 | no delay (0). | |
486 | Format: integer | |
487 | ||
488 | bootmem_debug [KNL] Enable bootmem allocator debug messages. | |
489 | ||
490 | bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) | |
491 | bttv.radio= Most important insmod options are available as | |
492 | kernel args too. | |
493 | bttv.pll= See Documentation/video4linux/bttv/Insmod-options | |
494 | bttv.tuner= | |
495 | ||
496 | bulk_remove=off [PPC] This parameter disables the use of the pSeries | |
497 | firmware feature for flushing multiple hpte entries | |
498 | at a time. | |
499 | ||
500 | c101= [NET] Moxa C101 synchronous serial card | |
501 | ||
502 | cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. | |
503 | Sometimes CPU hardware bugs make them report the cache | |
504 | size incorrectly. The kernel will attempt work arounds | |
505 | to fix known problems, but for some CPUs it is not | |
506 | possible to determine what the correct size should be. | |
507 | This option provides an override for these situations. | |
508 | ||
509 | ccw_timeout_log [S390] | |
510 | See Documentation/s390/CommonIO for details. | |
511 | ||
512 | cgroup_disable= [KNL] Disable a particular controller | |
513 | Format: {name of the controller(s) to disable} | |
514 | {Currently supported controllers - "memory"} | |
515 | ||
516 | checkreqprot [SELINUX] Set initial checkreqprot flag value. | |
517 | Format: { "0" | "1" } | |
518 | See security/selinux/Kconfig help text. | |
519 | 0 -- check protection applied by kernel (includes | |
520 | any implied execute protection). | |
521 | 1 -- check protection requested by application. | |
522 | Default value is set via a kernel config option. | |
523 | Value can be changed at runtime via | |
524 | /selinux/checkreqprot. | |
525 | ||
526 | cio_ignore= [S390] | |
527 | See Documentation/s390/CommonIO for details. | |
528 | clk_ignore_unused | |
529 | [CLK] | |
530 | Keep all clocks already enabled by bootloader on, | |
531 | even if no driver has claimed them. This is useful | |
532 | for debug and development, but should not be | |
533 | needed on a platform with proper driver support. | |
534 | For more information, see Documentation/clk.txt. | |
535 | ||
536 | clock= [BUGS=X86-32, HW] gettimeofday clocksource override. | |
537 | [Deprecated] | |
538 | Forces specified clocksource (if available) to be used | |
539 | when calculating gettimeofday(). If specified | |
540 | clocksource is not available, it defaults to PIT. | |
541 | Format: { pit | tsc | cyclone | pmtmr } | |
542 | ||
543 | clocksource= Override the default clocksource | |
544 | Format: <string> | |
545 | Override the default clocksource and use the clocksource | |
546 | with the name specified. | |
547 | Some clocksource names to choose from, depending on | |
548 | the platform: | |
549 | [all] jiffies (this is the base, fallback clocksource) | |
550 | [ACPI] acpi_pm | |
551 | [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, | |
552 | pxa_timer,timer3,32k_counter,timer0_1 | |
553 | [AVR32] avr32 | |
554 | [X86-32] pit,hpet,tsc; | |
555 | scx200_hrt on Geode; cyclone on IBM x440 | |
556 | [MIPS] MIPS | |
557 | [PARISC] cr16 | |
558 | [S390] tod | |
559 | [SH] SuperH | |
560 | [SPARC64] tick | |
561 | [X86-64] hpet,tsc | |
562 | ||
563 | clearcpuid=BITNUM [X86] | |
564 | Disable CPUID feature X for the kernel. See | |
565 | arch/x86/include/asm/cpufeature.h for the valid bit | |
566 | numbers. Note the Linux specific bits are not necessarily | |
567 | stable over kernel options, but the vendor specific | |
568 | ones should be. | |
569 | Also note that user programs calling CPUID directly | |
570 | or using the feature without checking anything | |
571 | will still see it. This just prevents it from | |
572 | being used by the kernel or shown in /proc/cpuinfo. | |
573 | Also note the kernel might malfunction if you disable | |
574 | some critical bits. | |
575 | ||
576 | cma=nn[MG] [ARM,KNL] | |
577 | Sets the size of kernel global memory area for contiguous | |
578 | memory allocations. For more information, see | |
579 | include/linux/dma-contiguous.h | |
580 | ||
581 | cmo_free_hint= [PPC] Format: { yes | no } | |
582 | Specify whether pages are marked as being inactive | |
583 | when they are freed. This is used in CMO environments | |
584 | to determine OS memory pressure for page stealing by | |
585 | a hypervisor. | |
586 | Default: yes | |
587 | ||
588 | coherent_pool=nn[KMG] [ARM,KNL] | |
589 | Sets the size of memory pool for coherent, atomic dma | |
590 | allocations, by default set to 256K. | |
591 | ||
592 | code_bytes [X86] How many bytes of object code to print | |
593 | in an oops report. | |
594 | Range: 0 - 8192 | |
595 | Default: 64 | |
596 | ||
597 | com20020= [HW,NET] ARCnet - COM20020 chipset | |
598 | Format: | |
599 | <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] | |
600 | ||
601 | com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) | |
602 | Format: <io>[,<irq>] | |
603 | ||
604 | com90xx= [HW,NET] | |
605 | ARCnet - COM90xx chipset (memory-mapped buffers) | |
606 | Format: <io>[,<irq>[,<memstart>]] | |
607 | ||
608 | condev= [HW,S390] console device | |
609 | conmode= | |
610 | ||
611 | console= [KNL] Output console device and options. | |
612 | ||
613 | tty<n> Use the virtual console device <n>. | |
614 | ||
615 | ttyS<n>[,options] | |
616 | ttyUSB0[,options] | |
617 | Use the specified serial port. The options are of | |
618 | the form "bbbbpnf", where "bbbb" is the baud rate, | |
619 | "p" is parity ("n", "o", or "e"), "n" is number of | |
620 | bits, and "f" is flow control ("r" for RTS or | |
621 | omit it). Default is "9600n8". | |
622 | ||
623 | See Documentation/serial-console.txt for more | |
624 | information. See | |
625 | Documentation/networking/netconsole.txt for an | |
626 | alternative. | |
627 | ||
628 | uart[8250],io,<addr>[,options] | |
629 | uart[8250],mmio,<addr>[,options] | |
630 | Start an early, polled-mode console on the 8250/16550 | |
631 | UART at the specified I/O port or MMIO address, | |
632 | switching to the matching ttyS device later. The | |
633 | options are the same as for ttyS, above. | |
634 | hvc<n> Use the hypervisor console device <n>. This is for | |
635 | both Xen and PowerPC hypervisors. | |
636 | ||
637 | If the device connected to the port is not a TTY but a braille | |
638 | device, prepend "brl," before the device type, for instance | |
639 | console=brl,ttyS0 | |
640 | For now, only VisioBraille is supported. | |
641 | ||
642 | consoleblank= [KNL] The console blank (screen saver) timeout in | |
643 | seconds. Defaults to 10*60 = 10mins. A value of 0 | |
644 | disables the blank timer. | |
645 | ||
646 | coredump_filter= | |
647 | [KNL] Change the default value for | |
648 | /proc/<pid>/coredump_filter. | |
649 | See also Documentation/filesystems/proc.txt. | |
650 | ||
651 | cpuidle.off=1 [CPU_IDLE] | |
652 | disable the cpuidle sub-system | |
653 | ||
654 | cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver | |
655 | Format: | |
656 | <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] | |
657 | ||
658 | crashkernel=size[KMG][@offset[KMG]] | |
659 | [KNL] Using kexec, Linux can switch to a 'crash kernel' | |
660 | upon panic. This parameter reserves the physical | |
661 | memory region [offset, offset + size] for that kernel | |
662 | image. If '@offset' is omitted, then a suitable offset | |
663 | is selected automatically. Check | |
664 | Documentation/kdump/kdump.txt for further details. | |
665 | ||
666 | crashkernel=range1:size1[,range2:size2,...][@offset] | |
667 | [KNL] Same as above, but depends on the memory | |
668 | in the running system. The syntax of range is | |
669 | start-[end] where start and end are both | |
670 | a memory unit (amount[KMG]). See also | |
671 | Documentation/kdump/kdump.txt for an example. | |
672 | ||
673 | crashkernel=size[KMG],high | |
674 | [KNL, x86_64] range could be above 4G. Allow kernel | |
675 | to allocate physical memory region from top, so could | |
676 | be above 4G if system have more than 4G ram installed. | |
677 | Otherwise memory region will be allocated below 4G, if | |
678 | available. | |
679 | It will be ignored if crashkernel=X is specified. | |
680 | crashkernel=size[KMG],low | |
681 | [KNL, x86_64] range under 4G. When crashkernel=X,high | |
682 | is passed, kernel could allocate physical memory region | |
683 | above 4G, that cause second kernel crash on system | |
684 | that require some amount of low memory, e.g. swiotlb | |
685 | requires at least 64M+32K low memory. Kernel would | |
686 | try to allocate 72M below 4G automatically. | |
687 | This one let user to specify own low range under 4G | |
688 | for second kernel instead. | |
689 | 0: to disable low allocation. | |
690 | It will be ignored when crashkernel=X,high is not used | |
691 | or memory reserved is below 4G. | |
692 | ||
693 | cs89x0_dma= [HW,NET] | |
694 | Format: <dma> | |
695 | ||
696 | cs89x0_media= [HW,NET] | |
697 | Format: { rj45 | aui | bnc } | |
698 | ||
699 | dasd= [HW,NET] | |
700 | See header of drivers/s390/block/dasd_devmap.c. | |
701 | ||
702 | db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port | |
703 | (one device per port) | |
704 | Format: <port#>,<type> | |
705 | See also Documentation/input/joystick-parport.txt | |
706 | ||
707 | ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot | |
708 | time. See Documentation/dynamic-debug-howto.txt for | |
709 | details. Deprecated, see dyndbg. | |
710 | ||
711 | debug [KNL] Enable kernel debugging (events log level). | |
712 | ||
713 | debug_locks_verbose= | |
714 | [KNL] verbose self-tests | |
715 | Format=<0|1> | |
716 | Print debugging info while doing the locking API | |
717 | self-tests. | |
718 | We default to 0 (no extra messages), setting it to | |
719 | 1 will print _a lot_ more information - normally | |
720 | only useful to kernel developers. | |
721 | ||
722 | debug_objects [KNL] Enable object debugging | |
723 | ||
724 | no_debug_objects | |
725 | [KNL] Disable object debugging | |
726 | ||
727 | debug_guardpage_minorder= | |
728 | [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this | |
729 | parameter allows control of the order of pages that will | |
730 | be intentionally kept free (and hence protected) by the | |
731 | buddy allocator. Bigger value increase the probability | |
732 | of catching random memory corruption, but reduce the | |
733 | amount of memory for normal system use. The maximum | |
734 | possible value is MAX_ORDER/2. Setting this parameter | |
735 | to 1 or 2 should be enough to identify most random | |
736 | memory corruption problems caused by bugs in kernel or | |
737 | driver code when a CPU writes to (or reads from) a | |
738 | random memory location. Note that there exists a class | |
739 | of memory corruptions problems caused by buggy H/W or | |
740 | F/W or by drivers badly programing DMA (basically when | |
741 | memory is written at bus level and the CPU MMU is | |
742 | bypassed) which are not detectable by | |
743 | CONFIG_DEBUG_PAGEALLOC, hence this option will not help | |
744 | tracking down these problems. | |
745 | ||
746 | debugpat [X86] Enable PAT debugging | |
747 | ||
748 | decnet.addr= [HW,NET] | |
749 | Format: <area>[,<node>] | |
750 | See also Documentation/networking/decnet.txt. | |
751 | ||
752 | default_hugepagesz= | |
753 | [same as hugepagesz=] The size of the default | |
754 | HugeTLB page size. This is the size represented by | |
755 | the legacy /proc/ hugepages APIs, used for SHM, and | |
756 | default size when mounting hugetlbfs filesystems. | |
757 | Defaults to the default architecture's huge page size | |
758 | if not specified. | |
759 | ||
760 | dhash_entries= [KNL] | |
761 | Set number of hash buckets for dentry cache. | |
762 | ||
763 | digi= [HW,SERIAL] | |
764 | IO parameters + enable/disable command. | |
765 | ||
766 | digiepca= [HW,SERIAL] | |
767 | See drivers/char/README.epca and | |
768 | Documentation/serial/digiepca.txt. | |
769 | ||
770 | disable= [IPV6] | |
771 | See Documentation/networking/ipv6.txt. | |
772 | ||
773 | disable_ddw [PPC/PSERIES] | |
774 | Disable Dynamic DMA Window support. Use this if | |
775 | to workaround buggy firmware. | |
776 | ||
777 | disable_ipv6= [IPV6] | |
778 | See Documentation/networking/ipv6.txt. | |
779 | ||
780 | disable_mtrr_cleanup [X86] | |
781 | The kernel tries to adjust MTRR layout from continuous | |
782 | to discrete, to make X server driver able to add WB | |
783 | entry later. This parameter disables that. | |
784 | ||
785 | disable_mtrr_trim [X86, Intel and AMD only] | |
786 | By default the kernel will trim any uncacheable | |
787 | memory out of your available memory pool based on | |
788 | MTRR settings. This parameter disables that behavior, | |
789 | possibly causing your machine to run very slowly. | |
790 | ||
791 | disable_timer_pin_1 [X86] | |
792 | Disable PIN 1 of APIC timer | |
793 | Can be useful to work around chipset bugs. | |
794 | ||
795 | dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, | |
796 | this option disables the debugging code at boot. | |
797 | ||
798 | dma_debug_entries=<number> | |
799 | This option allows to tune the number of preallocated | |
800 | entries for DMA-API debugging code. One entry is | |
801 | required per DMA-API allocation. Use this if the | |
802 | DMA-API debugging code disables itself because the | |
803 | architectural default is too low. | |
804 | ||
805 | dma_debug_driver=<driver_name> | |
806 | With this option the DMA-API debugging driver | |
807 | filter feature can be enabled at boot time. Just | |
808 | pass the driver to filter for as the parameter. | |
809 | The filter can be disabled or changed to another | |
810 | driver later using sysfs. | |
811 | ||
812 | drm_kms_helper.edid_firmware=[<connector>:]<file> | |
813 | Broken monitors, graphic adapters and KVMs may | |
814 | send no or incorrect EDID data sets. This parameter | |
815 | allows to specify an EDID data set in the | |
816 | /lib/firmware directory that is used instead. | |
817 | Generic built-in EDID data sets are used, if one of | |
818 | edid/1024x768.bin, edid/1280x1024.bin, | |
819 | edid/1680x1050.bin, or edid/1920x1080.bin is given | |
820 | and no file with the same name exists. Details and | |
821 | instructions how to build your own EDID data are | |
822 | available in Documentation/EDID/HOWTO.txt. An EDID | |
823 | data set will only be used for a particular connector, | |
824 | if its name and a colon are prepended to the EDID | |
825 | name. | |
826 | ||
827 | dscc4.setup= [NET] | |
828 | ||
829 | dyndbg[="val"] [KNL,DYNAMIC_DEBUG] | |
830 | module.dyndbg[="val"] | |
831 | Enable debug messages at boot time. See | |
832 | Documentation/dynamic-debug-howto.txt for details. | |
833 | ||
834 | earlycon= [KNL] Output early console device and options. | |
835 | uart[8250],io,<addr>[,options] | |
836 | uart[8250],mmio,<addr>[,options] | |
837 | uart[8250],mmio32,<addr>[,options] | |
838 | Start an early, polled-mode console on the 8250/16550 | |
839 | UART at the specified I/O port or MMIO address. | |
840 | MMIO inter-register address stride is either 8-bit | |
841 | (mmio) or 32-bit (mmio32). | |
842 | The options are the same as for ttyS, above. | |
843 | ||
844 | earlyprintk= [X86,SH,BLACKFIN,ARM] | |
845 | earlyprintk=vga | |
846 | earlyprintk=xen | |
847 | earlyprintk=serial[,ttySn[,baudrate]] | |
848 | earlyprintk=serial[,0x...[,baudrate]] | |
849 | earlyprintk=ttySn[,baudrate] | |
850 | earlyprintk=dbgp[debugController#] | |
851 | ||
852 | earlyprintk is useful when the kernel crashes before | |
853 | the normal console is initialized. It is not enabled by | |
854 | default because it has some cosmetic problems. | |
855 | ||
856 | Append ",keep" to not disable it when the real console | |
857 | takes over. | |
858 | ||
859 | Only vga or serial or usb debug port at a time. | |
860 | ||
861 | Currently only ttyS0 and ttyS1 may be specified by | |
862 | name. Other I/O ports may be explicitly specified | |
863 | on some architectures (x86 and arm at least) by | |
864 | replacing ttySn with an I/O port address, like this: | |
865 | earlyprintk=serial,0x1008,115200 | |
866 | You can find the port for a given device in | |
867 | /proc/tty/driver/serial: | |
868 | 2: uart:ST16650V2 port:00001008 irq:18 ... | |
869 | ||
870 | Interaction with the standard serial driver is not | |
871 | very good. | |
872 | ||
873 | The VGA output is eventually overwritten by the real | |
874 | console. | |
875 | ||
876 | The xen output can only be used by Xen PV guests. | |
877 | ||
878 | ekgdboc= [X86,KGDB] Allow early kernel console debugging | |
879 | ekgdboc=kbd | |
880 | ||
881 | This is designed to be used in conjunction with | |
882 | the boot argument: earlyprintk=vga | |
883 | ||
884 | edd= [EDD] | |
885 | Format: {"off" | "on" | "skip[mbr]"} | |
886 | ||
887 | efi_no_storage_paranoia [EFI; X86] | |
888 | Using this parameter you can use more than 50% of | |
889 | your efi variable storage. Use this parameter only if | |
890 | you are really sure that your UEFI does sane gc and | |
891 | fulfills the spec otherwise your board may brick. | |
892 | ||
893 | eisa_irq_edge= [PARISC,HW] | |
894 | See header of drivers/parisc/eisa.c. | |
895 | ||
896 | elanfreq= [X86-32] | |
897 | See comment before function elanfreq_setup() in | |
898 | arch/x86/kernel/cpu/cpufreq/elanfreq.c. | |
899 | ||
900 | elevator= [IOSCHED] | |
901 | Format: {"cfq" | "deadline" | "noop"} | |
902 | See Documentation/block/cfq-iosched.txt and | |
903 | Documentation/block/deadline-iosched.txt for details. | |
904 | ||
905 | elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] | |
906 | Specifies physical address of start of kernel core | |
907 | image elf header and optionally the size. Generally | |
908 | kexec loader will pass this option to capture kernel. | |
909 | See Documentation/kdump/kdump.txt for details. | |
910 | ||
911 | enable_mtrr_cleanup [X86] | |
912 | The kernel tries to adjust MTRR layout from continuous | |
913 | to discrete, to make X server driver able to add WB | |
914 | entry later. This parameter enables that. | |
915 | ||
916 | enable_timer_pin_1 [X86] | |
917 | Enable PIN 1 of APIC timer | |
918 | Can be useful to work around chipset bugs | |
919 | (in particular on some ATI chipsets). | |
920 | The kernel tries to set a reasonable default. | |
921 | ||
922 | enforcing [SELINUX] Set initial enforcing status. | |
923 | Format: {"0" | "1"} | |
924 | See security/selinux/Kconfig help text. | |
925 | 0 -- permissive (log only, no denials). | |
926 | 1 -- enforcing (deny and log). | |
927 | Default value is 0. | |
928 | Value can be changed at runtime via /selinux/enforce. | |
929 | ||
930 | erst_disable [ACPI] | |
931 | Disable Error Record Serialization Table (ERST) | |
932 | support. | |
933 | ||
934 | ether= [HW,NET] Ethernet cards parameters | |
935 | This option is obsoleted by the "netdev=" option, which | |
936 | has equivalent usage. See its documentation for details. | |
937 | ||
938 | evm= [EVM] | |
939 | Format: { "fix" } | |
940 | Permit 'security.evm' to be updated regardless of | |
941 | current integrity status. | |
942 | ||
943 | failslab= | |
944 | fail_page_alloc= | |
945 | fail_make_request=[KNL] | |
946 | General fault injection mechanism. | |
947 | Format: <interval>,<probability>,<space>,<times> | |
948 | See also Documentation/fault-injection/. | |
949 | ||
950 | floppy= [HW] | |
951 | See Documentation/blockdev/floppy.txt. | |
952 | ||
953 | force_pal_cache_flush | |
954 | [IA-64] Avoid check_sal_cache_flush which may hang on | |
955 | buggy SAL_CACHE_FLUSH implementations. Using this | |
956 | parameter will force ia64_sal_cache_flush to call | |
957 | ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. | |
958 | ||
959 | ftrace=[tracer] | |
960 | [FTRACE] will set and start the specified tracer | |
961 | as early as possible in order to facilitate early | |
962 | boot debugging. | |
963 | ||
964 | ftrace_dump_on_oops[=orig_cpu] | |
965 | [FTRACE] will dump the trace buffers on oops. | |
966 | If no parameter is passed, ftrace will dump | |
967 | buffers of all CPUs, but if you pass orig_cpu, it will | |
968 | dump only the buffer of the CPU that triggered the | |
969 | oops. | |
970 | ||
971 | ftrace_filter=[function-list] | |
972 | [FTRACE] Limit the functions traced by the function | |
973 | tracer at boot up. function-list is a comma separated | |
974 | list of functions. This list can be changed at run | |
975 | time by the set_ftrace_filter file in the debugfs | |
976 | tracing directory. | |
977 | ||
978 | ftrace_notrace=[function-list] | |
979 | [FTRACE] Do not trace the functions specified in | |
980 | function-list. This list can be changed at run time | |
981 | by the set_ftrace_notrace file in the debugfs | |
982 | tracing directory. | |
983 | ||
984 | ftrace_graph_filter=[function-list] | |
985 | [FTRACE] Limit the top level callers functions traced | |
986 | by the function graph tracer at boot up. | |
987 | function-list is a comma separated list of functions | |
988 | that can be changed at run time by the | |
989 | set_graph_function file in the debugfs tracing directory. | |
990 | ||
991 | gamecon.map[2|3]= | |
992 | [HW,JOY] Multisystem joystick and NES/SNES/PSX pad | |
993 | support via parallel port (up to 5 devices per port) | |
994 | Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> | |
995 | See also Documentation/input/joystick-parport.txt | |
996 | ||
997 | gamma= [HW,DRM] | |
998 | ||
999 | gart_fix_e820= [X86_64] disable the fix e820 for K8 GART | |
1000 | Format: off | on | |
1001 | default: on | |
1002 | ||
1003 | gcov_persist= [GCOV] When non-zero (default), profiling data for | |
1004 | kernel modules is saved and remains accessible via | |
1005 | debugfs, even when the module is unloaded/reloaded. | |
1006 | When zero, profiling data is discarded and associated | |
1007 | debugfs files are removed at module unload time. | |
1008 | ||
1009 | gpt [EFI] Forces disk with valid GPT signature but | |
1010 | invalid Protective MBR to be treated as GPT. | |
1011 | ||
1012 | grcan.enable0= [HW] Configuration of physical interface 0. Determines | |
1013 | the "Enable 0" bit of the configuration register. | |
1014 | Format: 0 | 1 | |
1015 | Default: 0 | |
1016 | grcan.enable1= [HW] Configuration of physical interface 1. Determines | |
1017 | the "Enable 0" bit of the configuration register. | |
1018 | Format: 0 | 1 | |
1019 | Default: 0 | |
1020 | grcan.select= [HW] Select which physical interface to use. | |
1021 | Format: 0 | 1 | |
1022 | Default: 0 | |
1023 | grcan.txsize= [HW] Sets the size of the tx buffer. | |
1024 | Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0. | |
1025 | Default: 1024 | |
1026 | grcan.rxsize= [HW] Sets the size of the rx buffer. | |
1027 | Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. | |
1028 | Default: 1024 | |
1029 | ||
1030 | hashdist= [KNL,NUMA] Large hashes allocated during boot | |
1031 | are distributed across NUMA nodes. Defaults on | |
1032 | for 64-bit NUMA, off otherwise. | |
1033 | Format: 0 | 1 (for off | on) | |
1034 | ||
1035 | hcl= [IA-64] SGI's Hardware Graph compatibility layer | |
1036 | ||
1037 | hd= [EIDE] (E)IDE hard drive subsystem geometry | |
1038 | Format: <cyl>,<head>,<sect> | |
1039 | ||
1040 | hest_disable [ACPI] | |
1041 | Disable Hardware Error Source Table (HEST) support; | |
1042 | corresponding firmware-first mode error processing | |
1043 | logic will be disabled. | |
1044 | ||
1045 | highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact | |
1046 | size of <nn>. This works even on boxes that have no | |
1047 | highmem otherwise. This also works to reduce highmem | |
1048 | size on bigger boxes. | |
1049 | ||
1050 | highres= [KNL] Enable/disable high resolution timer mode. | |
1051 | Valid parameters: "on", "off" | |
1052 | Default: "on" | |
1053 | ||
1054 | hisax= [HW,ISDN] | |
1055 | See Documentation/isdn/README.HiSax. | |
1056 | ||
1057 | hlt [BUGS=ARM,SH] | |
1058 | ||
1059 | hpet= [X86-32,HPET] option to control HPET usage | |
1060 | Format: { enable (default) | disable | force | | |
1061 | verbose } | |
1062 | disable: disable HPET and use PIT instead | |
1063 | force: allow force enabled of undocumented chips (ICH4, | |
1064 | VIA, nVidia) | |
1065 | verbose: show contents of HPET registers during setup | |
1066 | ||
1067 | hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. | |
1068 | hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. | |
1069 | On x86-64 and powerpc, this option can be specified | |
1070 | multiple times interleaved with hugepages= to reserve | |
1071 | huge pages of different sizes. Valid pages sizes on | |
1072 | x86-64 are 2M (when the CPU supports "pse") and 1G | |
1073 | (when the CPU supports the "pdpe1gb" cpuinfo flag) | |
1074 | Note that 1GB pages can only be allocated at boot time | |
1075 | using hugepages= and not freed afterwards. | |
1076 | ||
1077 | hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) | |
1078 | terminal devices. Valid values: 0..8 | |
1079 | hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. | |
1080 | If specified, z/VM IUCV HVC accepts connections | |
1081 | from listed z/VM user IDs only. | |
1082 | ||
1083 | hwthread_map= [METAG] Comma-separated list of Linux cpu id to | |
1084 | hardware thread id mappings. | |
1085 | Format: <cpu>:<hwthread> | |
1086 | ||
1087 | keep_bootcon [KNL] | |
1088 | Do not unregister boot console at start. This is only | |
1089 | useful for debugging when something happens in the window | |
1090 | between unregistering the boot console and initializing | |
1091 | the real console. | |
1092 | ||
1093 | i2c_bus= [HW] Override the default board specific I2C bus speed | |
1094 | or register an additional I2C bus that is not | |
1095 | registered from board initialization code. | |
1096 | Format: | |
1097 | <bus_id>,<clkrate> | |
1098 | ||
1099 | i8042.debug [HW] Toggle i8042 debug mode | |
1100 | i8042.direct [HW] Put keyboard port into non-translated mode | |
1101 | i8042.dumbkbd [HW] Pretend that controller can only read data from | |
1102 | keyboard and cannot control its state | |
1103 | (Don't attempt to blink the leds) | |
1104 | i8042.noaux [HW] Don't check for auxiliary (== mouse) port | |
1105 | i8042.nokbd [HW] Don't check/create keyboard port | |
1106 | i8042.noloop [HW] Disable the AUX Loopback command while probing | |
1107 | for the AUX port | |
1108 | i8042.nomux [HW] Don't check presence of an active multiplexing | |
1109 | controller | |
1110 | i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX | |
1111 | controllers | |
1112 | i8042.notimeout [HW] Ignore timeout condition signalled by controller | |
1113 | i8042.reset [HW] Reset the controller during init and cleanup | |
1114 | i8042.unlock [HW] Unlock (ignore) the keylock | |
1115 | ||
1116 | i810= [HW,DRM] | |
1117 | ||
1118 | i8k.ignore_dmi [HW] Continue probing hardware even if DMI data | |
1119 | indicates that the driver is running on unsupported | |
1120 | hardware. | |
1121 | i8k.force [HW] Activate i8k driver even if SMM BIOS signature | |
1122 | does not match list of supported models. | |
1123 | i8k.power_status | |
1124 | [HW] Report power status in /proc/i8k | |
1125 | (disabled by default) | |
1126 | i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN | |
1127 | capability is set. | |
1128 | ||
1129 | i915.invert_brightness= | |
1130 | [DRM] Invert the sense of the variable that is used to | |
1131 | set the brightness of the panel backlight. Normally a | |
1132 | brightness value of 0 indicates backlight switched off, | |
1133 | and the maximum of the brightness value sets the backlight | |
1134 | to maximum brightness. If this parameter is set to 0 | |
1135 | (default) and the machine requires it, or this parameter | |
1136 | is set to 1, a brightness value of 0 sets the backlight | |
1137 | to maximum brightness, and the maximum of the brightness | |
1138 | value switches the backlight off. | |
1139 | -1 -- never invert brightness | |
1140 | 0 -- machine default | |
1141 | 1 -- force brightness inversion | |
1142 | ||
1143 | icn= [HW,ISDN] | |
1144 | Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] | |
1145 | ||
1146 | ide-core.nodma= [HW] (E)IDE subsystem | |
1147 | Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc | |
1148 | .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr | |
1149 | .cdrom .chs .ignore_cable are additional options | |
1150 | See Documentation/ide/ide.txt. | |
1151 | ||
1152 | ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem | |
1153 | Claim all unknown PCI IDE storage controllers. | |
1154 | ||
1155 | idle= [X86] | |
1156 | Format: idle=poll, idle=halt, idle=nomwait | |
1157 | Poll forces a polling idle loop that can slightly | |
1158 | improve the performance of waking up a idle CPU, but | |
1159 | will use a lot of power and make the system run hot. | |
1160 | Not recommended. | |
1161 | idle=halt: Halt is forced to be used for CPU idle. | |
1162 | In such case C2/C3 won't be used again. | |
1163 | idle=nomwait: Disable mwait for CPU C-states | |
1164 | ||
1165 | ignore_loglevel [KNL] | |
1166 | Ignore loglevel setting - this will print /all/ | |
1167 | kernel messages to the console. Useful for debugging. | |
1168 | We also add it as printk module parameter, so users | |
1169 | could change it dynamically, usually by | |
1170 | /sys/module/printk/parameters/ignore_loglevel. | |
1171 | ||
1172 | ihash_entries= [KNL] | |
1173 | Set number of hash buckets for inode cache. | |
1174 | ||
1175 | ima_appraise= [IMA] appraise integrity measurements | |
1176 | Format: { "off" | "enforce" | "fix" } | |
1177 | default: "enforce" | |
1178 | ||
1179 | ima_appraise_tcb [IMA] | |
1180 | The builtin appraise policy appraises all files | |
1181 | owned by uid=0. | |
1182 | ||
1183 | ima_hash= [IMA] | |
1184 | Format: { "sha1" | "md5" } | |
1185 | default: "sha1" | |
1186 | ||
1187 | ima_tcb [IMA] | |
1188 | Load a policy which meets the needs of the Trusted | |
1189 | Computing Base. This means IMA will measure all | |
1190 | programs exec'd, files mmap'd for exec, and all files | |
1191 | opened for read by uid=0. | |
1192 | ||
1193 | init= [KNL] | |
1194 | Format: <full_path> | |
1195 | Run specified binary instead of /sbin/init as init | |
1196 | process. | |
1197 | ||
1198 | initcall_debug [KNL] Trace initcalls as they are executed. Useful | |
1199 | for working out where the kernel is dying during | |
1200 | startup. | |
1201 | ||
1202 | initrd= [BOOT] Specify the location of the initial ramdisk | |
1203 | ||
1204 | inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver | |
1205 | Format: <irq> | |
1206 | ||
1207 | int_pln_enable [x86] Enable power limit notification interrupt | |
1208 | ||
1209 | integrity_audit=[IMA] | |
1210 | Format: { "0" | "1" } | |
1211 | 0 -- basic integrity auditing messages. (Default) | |
1212 | 1 -- additional integrity auditing messages. | |
1213 | ||
1214 | intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option | |
1215 | on | |
1216 | Enable intel iommu driver. | |
1217 | off | |
1218 | Disable intel iommu driver. | |
1219 | igfx_off [Default Off] | |
1220 | By default, gfx is mapped as normal device. If a gfx | |
1221 | device has a dedicated DMAR unit, the DMAR unit is | |
1222 | bypassed by not enabling DMAR with this option. In | |
1223 | this case, gfx device will use physical address for | |
1224 | DMA. | |
1225 | forcedac [x86_64] | |
1226 | With this option iommu will not optimize to look | |
1227 | for io virtual address below 32-bit forcing dual | |
1228 | address cycle on pci bus for cards supporting greater | |
1229 | than 32-bit addressing. The default is to look | |
1230 | for translation below 32-bit and if not available | |
1231 | then look in the higher range. | |
1232 | strict [Default Off] | |
1233 | With this option on every unmap_single operation will | |
1234 | result in a hardware IOTLB flush operation as opposed | |
1235 | to batching them for performance. | |
1236 | sp_off [Default Off] | |
1237 | By default, super page will be supported if Intel IOMMU | |
1238 | has the capability. With this option, super page will | |
1239 | not be supported. | |
1240 | ||
1241 | intel_idle.max_cstate= [KNL,HW,ACPI,X86] | |
1242 | 0 disables intel_idle and fall back on acpi_idle. | |
1243 | 1 to 6 specify maximum depth of C-state. | |
1244 | ||
1245 | intel_pstate= [X86] | |
1246 | disable | |
1247 | Do not enable intel_pstate as the default | |
1248 | scaling driver for the supported processors | |
1249 | ||
1250 | intremap= [X86-64, Intel-IOMMU] | |
1251 | on enable Interrupt Remapping (default) | |
1252 | off disable Interrupt Remapping | |
1253 | nosid disable Source ID checking | |
1254 | no_x2apic_optout | |
1255 | BIOS x2APIC opt-out request will be ignored | |
1256 | ||
1257 | iomem= Disable strict checking of access to MMIO memory | |
1258 | strict regions from userspace. | |
1259 | relaxed | |
1260 | ||
1261 | iommu= [x86] | |
1262 | off | |
1263 | force | |
1264 | noforce | |
1265 | biomerge | |
1266 | panic | |
1267 | nopanic | |
1268 | merge | |
1269 | nomerge | |
1270 | forcesac | |
1271 | soft | |
1272 | pt [x86, IA-64] | |
1273 | ||
1274 | ||
1275 | io7= [HW] IO7 for Marvel based alpha systems | |
1276 | See comment before marvel_specify_io7 in | |
1277 | arch/alpha/kernel/core_marvel.c. | |
1278 | ||
1279 | io_delay= [X86] I/O delay method | |
1280 | 0x80 | |
1281 | Standard port 0x80 based delay | |
1282 | 0xed | |
1283 | Alternate port 0xed based delay (needed on some systems) | |
1284 | udelay | |
1285 | Simple two microseconds delay | |
1286 | none | |
1287 | No delay | |
1288 | ||
1289 | ip= [IP_PNP] | |
1290 | See Documentation/filesystems/nfs/nfsroot.txt. | |
1291 | ||
1292 | ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards | |
1293 | See comment before ip2_setup() in | |
1294 | drivers/char/ip2/ip2base.c. | |
1295 | ||
1296 | irqfixup [HW] | |
1297 | When an interrupt is not handled search all handlers | |
1298 | for it. Intended to get systems with badly broken | |
1299 | firmware running. | |
1300 | ||
1301 | irqpoll [HW] | |
1302 | When an interrupt is not handled search all handlers | |
1303 | for it. Also check all handlers each timer | |
1304 | interrupt. Intended to get systems with badly broken | |
1305 | firmware running. | |
1306 | ||
1307 | isapnp= [ISAPNP] | |
1308 | Format: <RDP>,<reset>,<pci_scan>,<verbosity> | |
1309 | ||
1310 | isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. | |
1311 | Format: | |
1312 | <cpu number>,...,<cpu number> | |
1313 | or | |
1314 | <cpu number>-<cpu number> | |
1315 | (must be a positive range in ascending order) | |
1316 | or a mixture | |
1317 | <cpu number>,...,<cpu number>-<cpu number> | |
1318 | ||
1319 | This option can be used to specify one or more CPUs | |
1320 | to isolate from the general SMP balancing and scheduling | |
1321 | algorithms. You can move a process onto or off an | |
1322 | "isolated" CPU via the CPU affinity syscalls or cpuset. | |
1323 | <cpu number> begins at 0 and the maximum value is | |
1324 | "number of CPUs in system - 1". | |
1325 | ||
1326 | This option is the preferred way to isolate CPUs. The | |
1327 | alternative -- manually setting the CPU mask of all | |
1328 | tasks in the system -- can cause problems and | |
1329 | suboptimal load balancer performance. | |
1330 | ||
1331 | iucv= [HW,NET] | |
1332 | ||
1333 | ivrs_ioapic [HW,X86_64] | |
1334 | Provide an override to the IOAPIC-ID<->DEVICE-ID | |
1335 | mapping provided in the IVRS ACPI table. For | |
1336 | example, to map IOAPIC-ID decimal 10 to | |
1337 | PCI device 00:14.0 write the parameter as: | |
1338 | ivrs_ioapic[10]=00:14.0 | |
1339 | ||
1340 | ivrs_hpet [HW,X86_64] | |
1341 | Provide an override to the HPET-ID<->DEVICE-ID | |
1342 | mapping provided in the IVRS ACPI table. For | |
1343 | example, to map HPET-ID decimal 0 to | |
1344 | PCI device 00:14.0 write the parameter as: | |
1345 | ivrs_hpet[0]=00:14.0 | |
1346 | ||
1347 | js= [HW,JOY] Analog joystick | |
1348 | See Documentation/input/joystick.txt. | |
1349 | ||
1350 | keepinitrd [HW,ARM] | |
1351 | ||
1352 | kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter | |
1353 | specifies the amount of memory usable by the kernel | |
1354 | for non-movable allocations. The requested amount is | |
1355 | spread evenly throughout all nodes in the system. The | |
1356 | remaining memory in each node is used for Movable | |
1357 | pages. In the event, a node is too small to have both | |
1358 | kernelcore and Movable pages, kernelcore pages will | |
1359 | take priority and other nodes will have a larger number | |
1360 | of kernelcore pages. The Movable zone is used for the | |
1361 | allocation of pages that may be reclaimed or moved | |
1362 | by the page migration subsystem. This means that | |
1363 | HugeTLB pages may not be allocated from this zone. | |
1364 | Note that allocations like PTEs-from-HighMem still | |
1365 | use the HighMem zone if it exists, and the Normal | |
1366 | zone if it does not. | |
1367 | ||
1368 | kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. | |
1369 | Format: <Controller#>[,poll interval] | |
1370 | The controller # is the number of the ehci usb debug | |
1371 | port as it is probed via PCI. The poll interval is | |
1372 | optional and is the number seconds in between | |
1373 | each poll cycle to the debug port in case you need | |
1374 | the functionality for interrupting the kernel with | |
1375 | gdb or control-c on the dbgp connection. When | |
1376 | not using this parameter you use sysrq-g to break into | |
1377 | the kernel debugger. | |
1378 | ||
1379 | kgdboc= [KGDB,HW] kgdb over consoles. | |
1380 | Requires a tty driver that supports console polling, | |
1381 | or a supported polling keyboard driver (non-usb). | |
1382 | Serial only format: <serial_device>[,baud] | |
1383 | keyboard only format: kbd | |
1384 | keyboard and serial format: kbd,<serial_device>[,baud] | |
1385 | Optional Kernel mode setting: | |
1386 | kms, kbd format: kms,kbd | |
1387 | kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] | |
1388 | ||
1389 | kgdbwait [KGDB] Stop kernel execution and enter the | |
1390 | kernel debugger at the earliest opportunity. | |
1391 | ||
1392 | kmac= [MIPS] korina ethernet MAC address. | |
1393 | Configure the RouterBoard 532 series on-chip | |
1394 | Ethernet adapter MAC address. | |
1395 | ||
1396 | kmemleak= [KNL] Boot-time kmemleak enable/disable | |
1397 | Valid arguments: on, off | |
1398 | Default: on | |
1399 | ||
1400 | kstack=N [X86] Print N words from the kernel stack | |
1401 | in oops dumps. | |
1402 | ||
1403 | kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. | |
1404 | Default is 0 (don't ignore, but inject #GP) | |
1405 | ||
1406 | kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit | |
1407 | KVM MMU at runtime. | |
1408 | Default is 0 (off) | |
1409 | ||
1410 | kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. | |
1411 | Default is 1 (enabled) | |
1412 | ||
1413 | kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) | |
1414 | for all guests. | |
1415 | Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. | |
1416 | ||
1417 | kvm-intel.ept= [KVM,Intel] Disable extended page tables | |
1418 | (virtualized MMU) support on capable Intel chips. | |
1419 | Default is 1 (enabled) | |
1420 | ||
1421 | kvm-intel.emulate_invalid_guest_state= | |
1422 | [KVM,Intel] Enable emulation of invalid guest states | |
1423 | Default is 0 (disabled) | |
1424 | ||
1425 | kvm-intel.flexpriority= | |
1426 | [KVM,Intel] Disable FlexPriority feature (TPR shadow). | |
1427 | Default is 1 (enabled) | |
1428 | ||
1429 | kvm-intel.nested= | |
1430 | [KVM,Intel] Enable VMX nesting (nVMX). | |
1431 | Default is 0 (disabled) | |
1432 | ||
1433 | kvm-intel.unrestricted_guest= | |
1434 | [KVM,Intel] Disable unrestricted guest feature | |
1435 | (virtualized real and unpaged mode) on capable | |
1436 | Intel chips. Default is 1 (enabled) | |
1437 | ||
1438 | kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification | |
1439 | feature (tagged TLBs) on capable Intel chips. | |
1440 | Default is 1 (enabled) | |
1441 | ||
1442 | l2cr= [PPC] | |
1443 | ||
1444 | l3cr= [PPC] | |
1445 | ||
1446 | lapic [X86-32,APIC] Enable the local APIC even if BIOS | |
1447 | disabled it. | |
1448 | ||
1449 | lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline | |
1450 | value for LAPIC timer one-shot implementation. Default | |
1451 | back to the programmable timer unit in the LAPIC. | |
1452 | ||
1453 | lapic_timer_c2_ok [X86,APIC] trust the local apic timer | |
1454 | in C2 power state. | |
1455 | ||
1456 | libata.dma= [LIBATA] DMA control | |
1457 | libata.dma=0 Disable all PATA and SATA DMA | |
1458 | libata.dma=1 PATA and SATA Disk DMA only | |
1459 | libata.dma=2 ATAPI (CDROM) DMA only | |
1460 | libata.dma=4 Compact Flash DMA only | |
1461 | Combinations also work, so libata.dma=3 enables DMA | |
1462 | for disks and CDROMs, but not CFs. | |
1463 | ||
1464 | libata.ignore_hpa= [LIBATA] Ignore HPA limit | |
1465 | libata.ignore_hpa=0 keep BIOS limits (default) | |
1466 | libata.ignore_hpa=1 ignore limits, using full disk | |
1467 | ||
1468 | libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume | |
1469 | when set. | |
1470 | Format: <int> | |
1471 | ||
1472 | libata.force= [LIBATA] Force configurations. The format is comma | |
1473 | separated list of "[ID:]VAL" where ID is | |
1474 | PORT[.DEVICE]. PORT and DEVICE are decimal numbers | |
1475 | matching port, link or device. Basically, it matches | |
1476 | the ATA ID string printed on console by libata. If | |
1477 | the whole ID part is omitted, the last PORT and DEVICE | |
1478 | values are used. If ID hasn't been specified yet, the | |
1479 | configuration applies to all ports, links and devices. | |
1480 | ||
1481 | If only DEVICE is omitted, the parameter applies to | |
1482 | the port and all links and devices behind it. DEVICE | |
1483 | number of 0 either selects the first device or the | |
1484 | first fan-out link behind PMP device. It does not | |
1485 | select the host link. DEVICE number of 15 selects the | |
1486 | host link and device attached to it. | |
1487 | ||
1488 | The VAL specifies the configuration to force. As long | |
1489 | as there's no ambiguity shortcut notation is allowed. | |
1490 | For example, both 1.5 and 1.5G would work for 1.5Gbps. | |
1491 | The following configurations can be forced. | |
1492 | ||
1493 | * Cable type: 40c, 80c, short40c, unk, ign or sata. | |
1494 | Any ID with matching PORT is used. | |
1495 | ||
1496 | * SATA link speed limit: 1.5Gbps or 3.0Gbps. | |
1497 | ||
1498 | * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. | |
1499 | udma[/][16,25,33,44,66,100,133] notation is also | |
1500 | allowed. | |
1501 | ||
1502 | * [no]ncq: Turn on or off NCQ. | |
1503 | ||
1504 | * nohrst, nosrst, norst: suppress hard, soft | |
1505 | and both resets. | |
1506 | ||
1507 | * rstonce: only attempt one reset during | |
1508 | hot-unplug link recovery | |
1509 | ||
1510 | * dump_id: dump IDENTIFY data. | |
1511 | ||
1512 | * atapi_dmadir: Enable ATAPI DMADIR bridge support | |
1513 | ||
1514 | If there are multiple matching configurations changing | |
1515 | the same attribute, the last one is used. | |
1516 | ||
1517 | memblock=debug [KNL] Enable memblock debug messages. | |
1518 | ||
1519 | load_ramdisk= [RAM] List of ramdisks to load from floppy | |
1520 | See Documentation/blockdev/ramdisk.txt. | |
1521 | ||
1522 | lockd.nlm_grace_period=P [NFS] Assign grace period. | |
1523 | Format: <integer> | |
1524 | ||
1525 | lockd.nlm_tcpport=N [NFS] Assign TCP port. | |
1526 | Format: <integer> | |
1527 | ||
1528 | lockd.nlm_timeout=T [NFS] Assign timeout value. | |
1529 | Format: <integer> | |
1530 | ||
1531 | lockd.nlm_udpport=M [NFS] Assign UDP port. | |
1532 | Format: <integer> | |
1533 | ||
1534 | logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver | |
1535 | Format: <irq> | |
1536 | ||
1537 | loglevel= All Kernel Messages with a loglevel smaller than the | |
1538 | console loglevel will be printed to the console. It can | |
1539 | also be changed with klogd or other programs. The | |
1540 | loglevels are defined as follows: | |
1541 | ||
1542 | 0 (KERN_EMERG) system is unusable | |
1543 | 1 (KERN_ALERT) action must be taken immediately | |
1544 | 2 (KERN_CRIT) critical conditions | |
1545 | 3 (KERN_ERR) error conditions | |
1546 | 4 (KERN_WARNING) warning conditions | |
1547 | 5 (KERN_NOTICE) normal but significant condition | |
1548 | 6 (KERN_INFO) informational | |
1549 | 7 (KERN_DEBUG) debug-level messages | |
1550 | ||
1551 | log_buf_len=n[KMG] Sets the size of the printk ring buffer, | |
1552 | in bytes. n must be a power of two. The default | |
1553 | size is set in the kernel config file. | |
1554 | ||
1555 | logo.nologo [FB] Disables display of the built-in Linux logo. | |
1556 | This may be used to provide more screen space for | |
1557 | kernel log messages and is useful when debugging | |
1558 | kernel boot problems. | |
1559 | ||
1560 | lp=0 [LP] Specify parallel ports to use, e.g, | |
1561 | lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses | |
1562 | lp=reset first parallel port). 'lp=0' disables the | |
1563 | lp=auto printer driver. 'lp=reset' (which can be | |
1564 | specified in addition to the ports) causes | |
1565 | attached printers to be reset. Using | |
1566 | lp=port1,port2,... specifies the parallel ports | |
1567 | to associate lp devices with, starting with | |
1568 | lp0. A port specification may be 'none' to skip | |
1569 | that lp device, or a parport name such as | |
1570 | 'parport0'. Specifying 'lp=auto' instead of a | |
1571 | port specification list means that device IDs | |
1572 | from each port should be examined, to see if | |
1573 | an IEEE 1284-compliant printer is attached; if | |
1574 | so, the driver will manage that printer. | |
1575 | See also header of drivers/char/lp.c. | |
1576 | ||
1577 | lpj=n [KNL] | |
1578 | Sets loops_per_jiffy to given constant, thus avoiding | |
1579 | time-consuming boot-time autodetection (up to 250 ms per | |
1580 | CPU). 0 enables autodetection (default). To determine | |
1581 | the correct value for your kernel, boot with normal | |
1582 | autodetection and see what value is printed. Note that | |
1583 | on SMP systems the preset will be applied to all CPUs, | |
1584 | which is likely to cause problems if your CPUs need | |
1585 | significantly divergent settings. An incorrect value | |
1586 | will cause delays in the kernel to be wrong, leading to | |
1587 | unpredictable I/O errors and other breakage. Although | |
1588 | unlikely, in the extreme case this might damage your | |
1589 | hardware. | |
1590 | ||
1591 | ltpc= [NET] | |
1592 | Format: <io>,<irq>,<dma> | |
1593 | ||
1594 | machvec= [IA-64] Force the use of a particular machine-vector | |
1595 | (machvec) in a generic kernel. | |
1596 | Example: machvec=hpzx1_swiotlb | |
1597 | ||
1598 | machtype= [Loongson] Share the same kernel image file between different | |
1599 | yeeloong laptop. | |
1600 | Example: machtype=lemote-yeeloong-2f-7inch | |
1601 | ||
1602 | max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater | |
1603 | than or equal to this physical address is ignored. | |
1604 | ||
1605 | maxcpus= [SMP] Maximum number of processors that an SMP kernel | |
1606 | should make use of. maxcpus=n : n >= 0 limits the | |
1607 | kernel to using 'n' processors. n=0 is a special case, | |
1608 | it is equivalent to "nosmp", which also disables | |
1609 | the IO APIC. | |
1610 | ||
1611 | max_loop= [LOOP] The number of loop block devices that get | |
1612 | (loop.max_loop) unconditionally pre-created at init time. The default | |
1613 | number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead | |
1614 | of statically allocating a predefined number, loop | |
1615 | devices can be requested on-demand with the | |
1616 | /dev/loop-control interface. | |
1617 | ||
1618 | mce [X86-32] Machine Check Exception | |
1619 | ||
1620 | mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt | |
1621 | ||
1622 | md= [HW] RAID subsystems devices and level | |
1623 | See Documentation/md.txt. | |
1624 | ||
1625 | mdacon= [MDA] | |
1626 | Format: <first>,<last> | |
1627 | Specifies range of consoles to be captured by the MDA. | |
1628 | ||
1629 | mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory | |
1630 | Amount of memory to be used when the kernel is not able | |
1631 | to see the whole system memory or for test. | |
1632 | [X86] Work as limiting max address. Use together | |
1633 | with memmap= to avoid physical address space collisions. | |
1634 | Without memmap= PCI devices could be placed at addresses | |
1635 | belonging to unused RAM. | |
1636 | ||
1637 | mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel | |
1638 | memory. | |
1639 | ||
1640 | memchunk=nn[KMG] | |
1641 | [KNL,SH] Allow user to override the default size for | |
1642 | per-device physically contiguous DMA buffers. | |
1643 | ||
1644 | memmap=exactmap [KNL,X86] Enable setting of an exact | |
1645 | E820 memory map, as specified by the user. | |
1646 | Such memmap=exactmap lines can be constructed based on | |
1647 | BIOS output or other requirements. See the memmap=nn@ss | |
1648 | option description. | |
1649 | ||
1650 | memmap=nn[KMG]@ss[KMG] | |
1651 | [KNL] Force usage of a specific region of memory | |
1652 | Region of memory to be used, from ss to ss+nn. | |
1653 | ||
1654 | memmap=nn[KMG]#ss[KMG] | |
1655 | [KNL,ACPI] Mark specific memory as ACPI data. | |
1656 | Region of memory to be used, from ss to ss+nn. | |
1657 | ||
1658 | memmap=nn[KMG]$ss[KMG] | |
1659 | [KNL,ACPI] Mark specific memory as reserved. | |
1660 | Region of memory to be used, from ss to ss+nn. | |
1661 | Example: Exclude memory from 0x18690000-0x1869ffff | |
1662 | memmap=64K$0x18690000 | |
1663 | or | |
1664 | memmap=0x10000$0x18690000 | |
1665 | ||
1666 | memory_corruption_check=0/1 [X86] | |
1667 | Some BIOSes seem to corrupt the first 64k of | |
1668 | memory when doing things like suspend/resume. | |
1669 | Setting this option will scan the memory | |
1670 | looking for corruption. Enabling this will | |
1671 | both detect corruption and prevent the kernel | |
1672 | from using the memory being corrupted. | |
1673 | However, its intended as a diagnostic tool; if | |
1674 | repeatable BIOS-originated corruption always | |
1675 | affects the same memory, you can use memmap= | |
1676 | to prevent the kernel from using that memory. | |
1677 | ||
1678 | memory_corruption_check_size=size [X86] | |
1679 | By default it checks for corruption in the low | |
1680 | 64k, making this memory unavailable for normal | |
1681 | use. Use this parameter to scan for | |
1682 | corruption in more or less memory. | |
1683 | ||
1684 | memory_corruption_check_period=seconds [X86] | |
1685 | By default it checks for corruption every 60 | |
1686 | seconds. Use this parameter to check at some | |
1687 | other rate. 0 disables periodic checking. | |
1688 | ||
1689 | memtest= [KNL,X86] Enable memtest | |
1690 | Format: <integer> | |
1691 | default : 0 <disable> | |
1692 | Specifies the number of memtest passes to be | |
1693 | performed. Each pass selects another test | |
1694 | pattern from a given set of patterns. Memtest | |
1695 | fills the memory with this pattern, validates | |
1696 | memory contents and reserves bad memory | |
1697 | regions that are detected. | |
1698 | ||
1699 | meye.*= [HW] Set MotionEye Camera parameters | |
1700 | See Documentation/video4linux/meye.txt. | |
1701 | ||
1702 | mfgpt_irq= [IA-32] Specify the IRQ to use for the | |
1703 | Multi-Function General Purpose Timers on AMD Geode | |
1704 | platforms. | |
1705 | ||
1706 | mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when | |
1707 | the BIOS has incorrectly applied a workaround. TinyBIOS | |
1708 | version 0.98 is known to be affected, 0.99 fixes the | |
1709 | problem by letting the user disable the workaround. | |
1710 | ||
1711 | mga= [HW,DRM] | |
1712 | ||
1713 | min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this | |
1714 | physical address is ignored. | |
1715 | ||
1716 | mini2440= [ARM,HW,KNL] | |
1717 | Format:[0..2][b][c][t] | |
1718 | Default: "0tb" | |
1719 | MINI2440 configuration specification: | |
1720 | 0 - The attached screen is the 3.5" TFT | |
1721 | 1 - The attached screen is the 7" TFT | |
1722 | 2 - The VGA Shield is attached (1024x768) | |
1723 | Leaving out the screen size parameter will not load | |
1724 | the TFT driver, and the framebuffer will be left | |
1725 | unconfigured. | |
1726 | b - Enable backlight. The TFT backlight pin will be | |
1727 | linked to the kernel VESA blanking code and a GPIO | |
1728 | LED. This parameter is not necessary when using the | |
1729 | VGA shield. | |
1730 | c - Enable the s3c camera interface. | |
1731 | t - Reserved for enabling touchscreen support. The | |
1732 | touchscreen support is not enabled in the mainstream | |
1733 | kernel as of 2.6.30, a preliminary port can be found | |
1734 | in the "bleeding edge" mini2440 support kernel at | |
1735 | http://repo.or.cz/w/linux-2.6/mini2440.git | |
1736 | ||
1737 | mminit_loglevel= | |
1738 | [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this | |
1739 | parameter allows control of the logging verbosity for | |
1740 | the additional memory initialisation checks. A value | |
1741 | of 0 disables mminit logging and a level of 4 will | |
1742 | log everything. Information is printed at KERN_DEBUG | |
1743 | so loglevel=8 may also need to be specified. | |
1744 | ||
1745 | module.sig_enforce | |
1746 | [KNL] When CONFIG_MODULE_SIG is set, this means that | |
1747 | modules without (valid) signatures will fail to load. | |
1748 | Note that if CONFIG_MODULE_SIG_FORCE is set, that | |
1749 | is always true, so this option does nothing. | |
1750 | ||
1751 | mousedev.tap_time= | |
1752 | [MOUSE] Maximum time between finger touching and | |
1753 | leaving touchpad surface for touch to be considered | |
1754 | a tap and be reported as a left button click (for | |
1755 | touchpads working in absolute mode only). | |
1756 | Format: <msecs> | |
1757 | mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices | |
1758 | reporting absolute coordinates, such as tablets | |
1759 | mousedev.yres= [MOUSE] Vertical screen resolution, used for devices | |
1760 | reporting absolute coordinates, such as tablets | |
1761 | ||
1762 | movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter | |
1763 | is similar to kernelcore except it specifies the | |
1764 | amount of memory used for migratable allocations. | |
1765 | If both kernelcore and movablecore is specified, | |
1766 | then kernelcore will be at *least* the specified | |
1767 | value but may be more. If movablecore on its own | |
1768 | is specified, the administrator must be careful | |
1769 | that the amount of memory usable for all allocations | |
1770 | is not too small. | |
1771 | ||
1772 | MTD_Partition= [MTD] | |
1773 | Format: <name>,<region-number>,<size>,<offset> | |
1774 | ||
1775 | MTD_Region= [MTD] Format: | |
1776 | <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] | |
1777 | ||
1778 | mtdparts= [MTD] | |
1779 | See drivers/mtd/cmdlinepart.c. | |
1780 | ||
1781 | multitce=off [PPC] This parameter disables the use of the pSeries | |
1782 | firmware feature for updating multiple TCE entries | |
1783 | at a time. | |
1784 | ||
1785 | onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration | |
1786 | ||
1787 | Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] | |
1788 | ||
1789 | boundary - index of last SLC block on Flex-OneNAND. | |
1790 | The remaining blocks are configured as MLC blocks. | |
1791 | lock - Configure if Flex-OneNAND boundary should be locked. | |
1792 | Once locked, the boundary cannot be changed. | |
1793 | 1 indicates lock status, 0 indicates unlock status. | |
1794 | ||
1795 | mtdset= [ARM] | |
1796 | ARM/S3C2412 JIVE boot control | |
1797 | ||
1798 | See arch/arm/mach-s3c2412/mach-jive.c | |
1799 | ||
1800 | mtouchusb.raw_coordinates= | |
1801 | [HW] Make the MicroTouch USB driver use raw coordinates | |
1802 | ('y', default) or cooked coordinates ('n') | |
1803 | ||
1804 | mtrr_chunk_size=nn[KMG] [X86] | |
1805 | used for mtrr cleanup. It is largest continuous chunk | |
1806 | that could hold holes aka. UC entries. | |
1807 | ||
1808 | mtrr_gran_size=nn[KMG] [X86] | |
1809 | Used for mtrr cleanup. It is granularity of mtrr block. | |
1810 | Default is 1. | |
1811 | Large value could prevent small alignment from | |
1812 | using up MTRRs. | |
1813 | ||
1814 | mtrr_spare_reg_nr=n [X86] | |
1815 | Format: <integer> | |
1816 | Range: 0,7 : spare reg number | |
1817 | Default : 1 | |
1818 | Used for mtrr cleanup. It is spare mtrr entries number. | |
1819 | Set to 2 or more if your graphical card needs more. | |
1820 | ||
1821 | n2= [NET] SDL Inc. RISCom/N2 synchronous serial card | |
1822 | ||
1823 | netdev= [NET] Network devices parameters | |
1824 | Format: <irq>,<io>,<mem_start>,<mem_end>,<name> | |
1825 | Note that mem_start is often overloaded to mean | |
1826 | something different and driver-specific. | |
1827 | This usage is only documented in each driver source | |
1828 | file if at all. | |
1829 | ||
1830 | nf_conntrack.acct= | |
1831 | [NETFILTER] Enable connection tracking flow accounting | |
1832 | 0 to disable accounting | |
1833 | 1 to enable accounting | |
1834 | Default value is 0. | |
1835 | ||
1836 | nfsaddrs= [NFS] Deprecated. Use ip= instead. | |
1837 | See Documentation/filesystems/nfs/nfsroot.txt. | |
1838 | ||
1839 | nfsroot= [NFS] nfs root filesystem for disk-less boxes. | |
1840 | See Documentation/filesystems/nfs/nfsroot.txt. | |
1841 | ||
1842 | nfsrootdebug [NFS] enable nfsroot debugging messages. | |
1843 | See Documentation/filesystems/nfs/nfsroot.txt. | |
1844 | ||
1845 | nfs.callback_tcpport= | |
1846 | [NFS] set the TCP port on which the NFSv4 callback | |
1847 | channel should listen. | |
1848 | ||
1849 | nfs.cache_getent= | |
1850 | [NFS] sets the pathname to the program which is used | |
1851 | to update the NFS client cache entries. | |
1852 | ||
1853 | nfs.cache_getent_timeout= | |
1854 | [NFS] sets the timeout after which an attempt to | |
1855 | update a cache entry is deemed to have failed. | |
1856 | ||
1857 | nfs.idmap_cache_timeout= | |
1858 | [NFS] set the maximum lifetime for idmapper cache | |
1859 | entries. | |
1860 | ||
1861 | nfs.enable_ino64= | |
1862 | [NFS] enable 64-bit inode numbers. | |
1863 | If zero, the NFS client will fake up a 32-bit inode | |
1864 | number for the readdir() and stat() syscalls instead | |
1865 | of returning the full 64-bit number. | |
1866 | The default is to return 64-bit inode numbers. | |
1867 | ||
1868 | nfs.max_session_slots= | |
1869 | [NFSv4.1] Sets the maximum number of session slots | |
1870 | the client will attempt to negotiate with the server. | |
1871 | This limits the number of simultaneous RPC requests | |
1872 | that the client can send to the NFSv4.1 server. | |
1873 | Note that there is little point in setting this | |
1874 | value higher than the max_tcp_slot_table_limit. | |
1875 | ||
1876 | nfs.nfs4_disable_idmapping= | |
1877 | [NFSv4] When set to the default of '1', this option | |
1878 | ensures that both the RPC level authentication | |
1879 | scheme and the NFS level operations agree to use | |
1880 | numeric uids/gids if the mount is using the | |
1881 | 'sec=sys' security flavour. In effect it is | |
1882 | disabling idmapping, which can make migration from | |
1883 | legacy NFSv2/v3 systems to NFSv4 easier. | |
1884 | Servers that do not support this mode of operation | |
1885 | will be autodetected by the client, and it will fall | |
1886 | back to using the idmapper. | |
1887 | To turn off this behaviour, set the value to '0'. | |
1888 | nfs.nfs4_unique_id= | |
1889 | [NFS4] Specify an additional fixed unique ident- | |
1890 | ification string that NFSv4 clients can insert into | |
1891 | their nfs_client_id4 string. This is typically a | |
1892 | UUID that is generated at system install time. | |
1893 | ||
1894 | nfs.send_implementation_id = | |
1895 | [NFSv4.1] Send client implementation identification | |
1896 | information in exchange_id requests. | |
1897 | If zero, no implementation identification information | |
1898 | will be sent. | |
1899 | The default is to send the implementation identification | |
1900 | information. | |
1901 | ||
1902 | nfs.recover_lost_locks = | |
1903 | [NFSv4] Attempt to recover locks that were lost due | |
1904 | to a lease timeout on the server. Please note that | |
1905 | doing this risks data corruption, since there are | |
1906 | no guarantees that the file will remain unchanged | |
1907 | after the locks are lost. | |
1908 | If you want to enable the kernel legacy behaviour of | |
1909 | attempting to recover these locks, then set this | |
1910 | parameter to '1'. | |
1911 | The default parameter value of '0' causes the kernel | |
1912 | not to attempt recovery of lost locks. | |
1913 | ||
1914 | nfsd.nfs4_disable_idmapping= | |
1915 | [NFSv4] When set to the default of '1', the NFSv4 | |
1916 | server will return only numeric uids and gids to | |
1917 | clients using auth_sys, and will accept numeric uids | |
1918 | and gids from such clients. This is intended to ease | |
1919 | migration from NFSv2/v3. | |
1920 | ||
1921 | objlayoutdriver.osd_login_prog= | |
1922 | [NFS] [OBJLAYOUT] sets the pathname to the program which | |
1923 | is used to automatically discover and login into new | |
1924 | osd-targets. Please see: | |
1925 | Documentation/filesystems/pnfs.txt for more explanations | |
1926 | ||
1927 | nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take | |
1928 | when a NMI is triggered. | |
1929 | Format: [state][,regs][,debounce][,die] | |
1930 | ||
1931 | nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels | |
1932 | Format: [panic,][nopanic,][num] | |
1933 | Valid num: 0 | |
1934 | 0 - turn nmi_watchdog off | |
1935 | When panic is specified, panic when an NMI watchdog | |
1936 | timeout occurs (or 'nopanic' to override the opposite | |
1937 | default). | |
1938 | This is useful when you use a panic=... timeout and | |
1939 | need the box quickly up again. | |
1940 | ||
1941 | netpoll.carrier_timeout= | |
1942 | [NET] Specifies amount of time (in seconds) that | |
1943 | netpoll should wait for a carrier. By default netpoll | |
1944 | waits 4 seconds. | |
1945 | ||
1946 | no387 [BUGS=X86-32] Tells the kernel to use the 387 maths | |
1947 | emulation library even if a 387 maths coprocessor | |
1948 | is present. | |
1949 | ||
1950 | no_console_suspend | |
1951 | [HW] Never suspend the console | |
1952 | Disable suspending of consoles during suspend and | |
1953 | hibernate operations. Once disabled, debugging | |
1954 | messages can reach various consoles while the rest | |
1955 | of the system is being put to sleep (ie, while | |
1956 | debugging driver suspend/resume hooks). This may | |
1957 | not work reliably with all consoles, but is known | |
1958 | to work with serial and VGA consoles. | |
1959 | To facilitate more flexible debugging, we also add | |
1960 | console_suspend, a printk module parameter to control | |
1961 | it. Users could use console_suspend (usually | |
1962 | /sys/module/printk/parameters/console_suspend) to | |
1963 | turn on/off it dynamically. | |
1964 | ||
1965 | noaliencache [MM, NUMA, SLAB] Disables the allocation of alien | |
1966 | caches in the slab allocator. Saves per-node memory, | |
1967 | but will impact performance. | |
1968 | ||
1969 | noalign [KNL,ARM] | |
1970 | ||
1971 | noapic [SMP,APIC] Tells the kernel to not make use of any | |
1972 | IOAPICs that may be present in the system. | |
1973 | ||
1974 | noautogroup Disable scheduler automatic task group creation. | |
1975 | ||
1976 | nobats [PPC] Do not use BATs for mapping kernel lowmem | |
1977 | on "Classic" PPC cores. | |
1978 | ||
1979 | nocache [ARM] | |
1980 | ||
1981 | noclflush [BUGS=X86] Don't use the CLFLUSH instruction | |
1982 | ||
1983 | nodelayacct [KNL] Disable per-task delay accounting | |
1984 | ||
1985 | nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. | |
1986 | ||
1987 | nodsp [SH] Disable hardware DSP at boot time. | |
1988 | ||
1989 | noefi [X86] Disable EFI runtime services support. | |
1990 | ||
1991 | noexec [IA-64] | |
1992 | ||
1993 | noexec [X86] | |
1994 | On X86-32 available only on PAE configured kernels. | |
1995 | noexec=on: enable non-executable mappings (default) | |
1996 | noexec=off: disable non-executable mappings | |
1997 | ||
1998 | nosmap [X86] | |
1999 | Disable SMAP (Supervisor Mode Access Prevention) | |
2000 | even if it is supported by processor. | |
2001 | ||
2002 | nosmep [X86] | |
2003 | Disable SMEP (Supervisor Mode Execution Prevention) | |
2004 | even if it is supported by processor. | |
2005 | ||
2006 | noexec32 [X86-64] | |
2007 | This affects only 32-bit executables. | |
2008 | noexec32=on: enable non-executable mappings (default) | |
2009 | read doesn't imply executable mappings | |
2010 | noexec32=off: disable non-executable mappings | |
2011 | read implies executable mappings | |
2012 | ||
2013 | nofpu [SH] Disable hardware FPU at boot time. | |
2014 | ||
2015 | nofxsr [BUGS=X86-32] Disables x86 floating point extended | |
2016 | register save and restore. The kernel will only save | |
2017 | legacy floating-point registers on task switch. | |
2018 | ||
2019 | noxsave [BUGS=X86] Disables x86 extended register state save | |
2020 | and restore using xsave. The kernel will fallback to | |
2021 | enabling legacy floating-point and sse state. | |
2022 | ||
2023 | eagerfpu= [X86] | |
2024 | on enable eager fpu restore | |
2025 | off disable eager fpu restore | |
2026 | auto selects the default scheme, which automatically | |
2027 | enables eagerfpu restore for xsaveopt. | |
2028 | ||
2029 | nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or | |
2030 | wfi(ARM) instruction doesn't work correctly and not to | |
2031 | use it. This is also useful when using JTAG debugger. | |
2032 | ||
2033 | no_file_caps Tells the kernel not to honor file capabilities. The | |
2034 | only way then for a file to be executed with privilege | |
2035 | is to be setuid root or executed by root. | |
2036 | ||
2037 | nohalt [IA-64] Tells the kernel not to use the power saving | |
2038 | function PAL_HALT_LIGHT when idle. This increases | |
2039 | power-consumption. On the positive side, it reduces | |
2040 | interrupt wake-up latency, which may improve performance | |
2041 | in certain environments such as networked servers or | |
2042 | real-time systems. | |
2043 | ||
2044 | nohz= [KNL] Boottime enable/disable dynamic ticks | |
2045 | Valid arguments: on, off | |
2046 | Default: on | |
2047 | ||
2048 | nohz_full= [KNL,BOOT] | |
2049 | In kernels built with CONFIG_NO_HZ_FULL=y, set | |
2050 | the specified list of CPUs whose tick will be stopped | |
2051 | whenever possible. The boot CPU will be forced outside | |
2052 | the range to maintain the timekeeping. | |
2053 | The CPUs in this range must also be included in the | |
2054 | rcu_nocbs= set. | |
2055 | ||
2056 | noiotrap [SH] Disables trapped I/O port accesses. | |
2057 | ||
2058 | noirqdebug [X86-32] Disables the code which attempts to detect and | |
2059 | disable unhandled interrupt sources. | |
2060 | ||
2061 | no_timer_check [X86,APIC] Disables the code which tests for | |
2062 | broken timer IRQ sources. | |
2063 | ||
2064 | noisapnp [ISAPNP] Disables ISA PnP code. | |
2065 | ||
2066 | noinitrd [RAM] Tells the kernel not to load any configured | |
2067 | initial RAM disk. | |
2068 | ||
2069 | nointremap [X86-64, Intel-IOMMU] Do not enable interrupt | |
2070 | remapping. | |
2071 | [Deprecated - use intremap=off] | |
2072 | ||
2073 | nointroute [IA-64] | |
2074 | ||
2075 | nojitter [IA-64] Disables jitter checking for ITC timers. | |
2076 | ||
2077 | no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver | |
2078 | ||
2079 | no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page | |
2080 | fault handling. | |
2081 | ||
2082 | no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. | |
2083 | steal time is computed, but won't influence scheduler | |
2084 | behaviour | |
2085 | ||
2086 | nolapic [X86-32,APIC] Do not enable or use the local APIC. | |
2087 | ||
2088 | nolapic_timer [X86-32,APIC] Do not use the local APIC timer. | |
2089 | ||
2090 | noltlbs [PPC] Do not use large page/tlb entries for kernel | |
2091 | lowmem mapping on PPC40x. | |
2092 | ||
2093 | nomca [IA-64] Disable machine check abort handling | |
2094 | ||
2095 | nomce [X86-32] Machine Check Exception | |
2096 | ||
2097 | nomfgpt [X86-32] Disable Multi-Function General Purpose | |
2098 | Timer usage (for AMD Geode machines). | |
2099 | ||
2100 | nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to | |
2101 | shutdown the other cpus. Instead use the REBOOT_VECTOR | |
2102 | irq. | |
2103 | ||
2104 | nomodule Disable module load | |
2105 | ||
2106 | nopat [X86] Disable PAT (page attribute table extension of | |
2107 | pagetables) support. | |
2108 | ||
2109 | norandmaps Don't use address space randomization. Equivalent to | |
2110 | echo 0 > /proc/sys/kernel/randomize_va_space | |
2111 | ||
2112 | noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops | |
2113 | ||
2114 | noreplace-smp [X86-32,SMP] Don't replace SMP instructions | |
2115 | with UP alternatives | |
2116 | ||
2117 | nordrand [X86] Disable the direct use of the RDRAND | |
2118 | instruction even if it is supported by the | |
2119 | processor. RDRAND is still available to user | |
2120 | space applications. | |
2121 | ||
2122 | noresume [SWSUSP] Disables resume and restores original swap | |
2123 | space. | |
2124 | ||
2125 | no-scroll [VGA] Disables scrollback. | |
2126 | This is required for the Braillex ib80-piezo Braille | |
2127 | reader made by F.H. Papenmeier (Germany). | |
2128 | ||
2129 | nosbagart [IA-64] | |
2130 | ||
2131 | nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. | |
2132 | ||
2133 | nosmp [SMP] Tells an SMP kernel to act as a UP kernel, | |
2134 | and disable the IO APIC. legacy for "maxcpus=0". | |
2135 | ||
2136 | nosoftlockup [KNL] Disable the soft-lockup detector. | |
2137 | ||
2138 | nosync [HW,M68K] Disables sync negotiation for all devices. | |
2139 | ||
2140 | notsc [BUGS=X86-32] Disable Time Stamp Counter | |
2141 | ||
2142 | nousb [USB] Disable the USB subsystem | |
2143 | ||
2144 | nowatchdog [KNL] Disable the lockup detector (NMI watchdog). | |
2145 | ||
2146 | nowb [ARM] | |
2147 | ||
2148 | nox2apic [X86-64,APIC] Do not enable x2APIC mode. | |
2149 | ||
2150 | cpu0_hotplug [X86] Turn on CPU0 hotplug feature when | |
2151 | CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. | |
2152 | Some features depend on CPU0. Known dependencies are: | |
2153 | 1. Resume from suspend/hibernate depends on CPU0. | |
2154 | Suspend/hibernate will fail if CPU0 is offline and you | |
2155 | need to online CPU0 before suspend/hibernate. | |
2156 | 2. PIC interrupts also depend on CPU0. CPU0 can't be | |
2157 | removed if a PIC interrupt is detected. | |
2158 | It's said poweroff/reboot may depend on CPU0 on some | |
2159 | machines although I haven't seen such issues so far | |
2160 | after CPU0 is offline on a few tested machines. | |
2161 | If the dependencies are under your control, you can | |
2162 | turn on cpu0_hotplug. | |
2163 | ||
2164 | nptcg= [IA-64] Override max number of concurrent global TLB | |
2165 | purges which is reported from either PAL_VM_SUMMARY or | |
2166 | SAL PALO. | |
2167 | ||
2168 | nr_cpus= [SMP] Maximum number of processors that an SMP kernel | |
2169 | could support. nr_cpus=n : n >= 1 limits the kernel to | |
2170 | supporting 'n' processors. Later in runtime you can not | |
2171 | use hotplug cpu feature to put more cpu back to online. | |
2172 | just like you compile the kernel NR_CPUS=n | |
2173 | ||
2174 | nr_uarts= [SERIAL] maximum number of UARTs to be registered. | |
2175 | ||
2176 | numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. | |
2177 | Allowed values are enable and disable | |
2178 | ||
2179 | numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. | |
2180 | one of ['zone', 'node', 'default'] can be specified | |
2181 | This can be set from sysctl after boot. | |
2182 | See Documentation/sysctl/vm.txt for details. | |
2183 | ||
2184 | ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. | |
2185 | See Documentation/debugging-via-ohci1394.txt for more | |
2186 | info. | |
2187 | ||
2188 | olpc_ec_timeout= [OLPC] ms delay when issuing EC commands | |
2189 | Rather than timing out after 20 ms if an EC | |
2190 | command is not properly ACKed, override the length | |
2191 | of the timeout. We have interrupts disabled while | |
2192 | waiting for the ACK, so if this is set too high | |
2193 | interrupts *may* be lost! | |
2194 | ||
2195 | omap_mux= [OMAP] Override bootloader pin multiplexing. | |
2196 | Format: <mux_mode0.mode_name=value>... | |
2197 | For example, to override I2C bus2: | |
2198 | omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 | |
2199 | ||
2200 | oprofile.timer= [HW] | |
2201 | Use timer interrupt instead of performance counters | |
2202 | ||
2203 | oprofile.cpu_type= Force an oprofile cpu type | |
2204 | This might be useful if you have an older oprofile | |
2205 | userland or if you want common events. | |
2206 | Format: { arch_perfmon } | |
2207 | arch_perfmon: [X86] Force use of architectural | |
2208 | perfmon on Intel CPUs instead of the | |
2209 | CPU specific event set. | |
2210 | timer: [X86] Force use of architectural NMI | |
2211 | timer mode (see also oprofile.timer | |
2212 | for generic hr timer mode) | |
2213 | [s390] Force legacy basic mode sampling | |
2214 | (report cpu_type "timer") | |
2215 | ||
2216 | oops=panic Always panic on oopses. Default is to just kill the | |
2217 | process, but there is a small probability of | |
2218 | deadlocking the machine. | |
2219 | This will also cause panics on machine check exceptions. | |
2220 | Useful together with panic=30 to trigger a reboot. | |
2221 | ||
2222 | OSS [HW,OSS] | |
2223 | See Documentation/sound/oss/oss-parameters.txt | |
2224 | ||
2225 | panic= [KNL] Kernel behaviour on panic: delay <timeout> | |
2226 | timeout > 0: seconds before rebooting | |
2227 | timeout = 0: wait forever | |
2228 | timeout < 0: reboot immediately | |
2229 | Format: <timeout> | |
2230 | ||
2231 | parkbd.port= [HW] Parallel port number the keyboard adapter is | |
2232 | connected to, default is 0. | |
2233 | Format: <parport#> | |
2234 | parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, | |
2235 | 0 for XT, 1 for AT (default is AT). | |
2236 | Format: <mode> | |
2237 | ||
2238 | parport= [HW,PPT] Specify parallel ports. 0 disables. | |
2239 | Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } | |
2240 | Use 'auto' to force the driver to use any | |
2241 | IRQ/DMA settings detected (the default is to | |
2242 | ignore detected IRQ/DMA settings because of | |
2243 | possible conflicts). You can specify the base | |
2244 | address, IRQ, and DMA settings; IRQ and DMA | |
2245 | should be numbers, or 'auto' (for using detected | |
2246 | settings on that particular port), or 'nofifo' | |
2247 | (to avoid using a FIFO even if it is detected). | |
2248 | Parallel ports are assigned in the order they | |
2249 | are specified on the command line, starting | |
2250 | with parport0. | |
2251 | ||
2252 | parport_init_mode= [HW,PPT] | |
2253 | Configure VIA parallel port to operate in | |
2254 | a specific mode. This is necessary on Pegasos | |
2255 | computer where firmware has no options for setting | |
2256 | up parallel port mode and sets it to spp. | |
2257 | Currently this function knows 686a and 8231 chips. | |
2258 | Format: [spp|ps2|epp|ecp|ecpepp] | |
2259 | ||
2260 | pause_on_oops= | |
2261 | Halt all CPUs after the first oops has been printed for | |
2262 | the specified number of seconds. This is to be used if | |
2263 | your oopses keep scrolling off the screen. | |
2264 | ||
2265 | pcbit= [HW,ISDN] | |
2266 | ||
2267 | pcd. [PARIDE] | |
2268 | See header of drivers/block/paride/pcd.c. | |
2269 | See also Documentation/blockdev/paride.txt. | |
2270 | ||
2271 | pci=option[,option...] [PCI] various PCI subsystem options: | |
2272 | earlydump [X86] dump PCI config space before the kernel | |
2273 | changes anything | |
2274 | off [X86] don't probe for the PCI bus | |
2275 | bios [X86-32] force use of PCI BIOS, don't access | |
2276 | the hardware directly. Use this if your machine | |
2277 | has a non-standard PCI host bridge. | |
2278 | nobios [X86-32] disallow use of PCI BIOS, only direct | |
2279 | hardware access methods are allowed. Use this | |
2280 | if you experience crashes upon bootup and you | |
2281 | suspect they are caused by the BIOS. | |
2282 | conf1 [X86] Force use of PCI Configuration | |
2283 | Mechanism 1. | |
2284 | conf2 [X86] Force use of PCI Configuration | |
2285 | Mechanism 2. | |
2286 | noaer [PCIE] If the PCIEAER kernel config parameter is | |
2287 | enabled, this kernel boot option can be used to | |
2288 | disable the use of PCIE advanced error reporting. | |
2289 | nodomains [PCI] Disable support for multiple PCI | |
2290 | root domains (aka PCI segments, in ACPI-speak). | |
2291 | nommconf [X86] Disable use of MMCONFIG for PCI | |
2292 | Configuration | |
2293 | check_enable_amd_mmconf [X86] check for and enable | |
2294 | properly configured MMIO access to PCI | |
2295 | config space on AMD family 10h CPU | |
2296 | nomsi [MSI] If the PCI_MSI kernel config parameter is | |
2297 | enabled, this kernel boot option can be used to | |
2298 | disable the use of MSI interrupts system-wide. | |
2299 | noioapicquirk [APIC] Disable all boot interrupt quirks. | |
2300 | Safety option to keep boot IRQs enabled. This | |
2301 | should never be necessary. | |
2302 | ioapicreroute [APIC] Enable rerouting of boot IRQs to the | |
2303 | primary IO-APIC for bridges that cannot disable | |
2304 | boot IRQs. This fixes a source of spurious IRQs | |
2305 | when the system masks IRQs. | |
2306 | noioapicreroute [APIC] Disable workaround that uses the | |
2307 | boot IRQ equivalent of an IRQ that connects to | |
2308 | a chipset where boot IRQs cannot be disabled. | |
2309 | The opposite of ioapicreroute. | |
2310 | biosirq [X86-32] Use PCI BIOS calls to get the interrupt | |
2311 | routing table. These calls are known to be buggy | |
2312 | on several machines and they hang the machine | |
2313 | when used, but on other computers it's the only | |
2314 | way to get the interrupt routing table. Try | |
2315 | this option if the kernel is unable to allocate | |
2316 | IRQs or discover secondary PCI buses on your | |
2317 | motherboard. | |
2318 | rom [X86] Assign address space to expansion ROMs. | |
2319 | Use with caution as certain devices share | |
2320 | address decoders between ROMs and other | |
2321 | resources. | |
2322 | norom [X86] Do not assign address space to | |
2323 | expansion ROMs that do not already have | |
2324 | BIOS assigned address ranges. | |
2325 | nobar [X86] Do not assign address space to the | |
2326 | BARs that weren't assigned by the BIOS. | |
2327 | irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be | |
2328 | assigned automatically to PCI devices. You can | |
2329 | make the kernel exclude IRQs of your ISA cards | |
2330 | this way. | |
2331 | pirqaddr=0xAAAAA [X86] Specify the physical address | |
2332 | of the PIRQ table (normally generated | |
2333 | by the BIOS) if it is outside the | |
2334 | F0000h-100000h range. | |
2335 | lastbus=N [X86] Scan all buses thru bus #N. Can be | |
2336 | useful if the kernel is unable to find your | |
2337 | secondary buses and you want to tell it | |
2338 | explicitly which ones they are. | |
2339 | assign-busses [X86] Always assign all PCI bus | |
2340 | numbers ourselves, overriding | |
2341 | whatever the firmware may have done. | |
2342 | usepirqmask [X86] Honor the possible IRQ mask stored | |
2343 | in the BIOS $PIR table. This is needed on | |
2344 | some systems with broken BIOSes, notably | |
2345 | some HP Pavilion N5400 and Omnibook XE3 | |
2346 | notebooks. This will have no effect if ACPI | |
2347 | IRQ routing is enabled. | |
2348 | noacpi [X86] Do not use ACPI for IRQ routing | |
2349 | or for PCI scanning. | |
2350 | use_crs [X86] Use PCI host bridge window information | |
2351 | from ACPI. On BIOSes from 2008 or later, this | |
2352 | is enabled by default. If you need to use this, | |
2353 | please report a bug. | |
2354 | nocrs [X86] Ignore PCI host bridge windows from ACPI. | |
2355 | If you need to use this, please report a bug. | |
2356 | routeirq Do IRQ routing for all PCI devices. | |
2357 | This is normally done in pci_enable_device(), | |
2358 | so this option is a temporary workaround | |
2359 | for broken drivers that don't call it. | |
2360 | skip_isa_align [X86] do not align io start addr, so can | |
2361 | handle more pci cards | |
2362 | firmware [ARM] Do not re-enumerate the bus but instead | |
2363 | just use the configuration from the | |
2364 | bootloader. This is currently used on | |
2365 | IXP2000 systems where the bus has to be | |
2366 | configured a certain way for adjunct CPUs. | |
2367 | noearly [X86] Don't do any early type 1 scanning. | |
2368 | This might help on some broken boards which | |
2369 | machine check when some devices' config space | |
2370 | is read. But various workarounds are disabled | |
2371 | and some IOMMU drivers will not work. | |
2372 | bfsort Sort PCI devices into breadth-first order. | |
2373 | This sorting is done to get a device | |
2374 | order compatible with older (<= 2.4) kernels. | |
2375 | nobfsort Don't sort PCI devices into breadth-first order. | |
2376 | pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) | |
2377 | tuning and use the BIOS-configured MPS defaults. | |
2378 | pcie_bus_safe Set every device's MPS to the largest value | |
2379 | supported by all devices below the root complex. | |
2380 | pcie_bus_perf Set device MPS to the largest allowable MPS | |
2381 | based on its parent bus. Also set MRRS (Max | |
2382 | Read Request Size) to the largest supported | |
2383 | value (no larger than the MPS that the device | |
2384 | or bus can support) for best performance. | |
2385 | pcie_bus_peer2peer Set every device's MPS to 128B, which | |
2386 | every device is guaranteed to support. This | |
2387 | configuration allows peer-to-peer DMA between | |
2388 | any pair of devices, possibly at the cost of | |
2389 | reduced performance. This also guarantees | |
2390 | that hot-added devices will work. | |
2391 | cbiosize=nn[KMG] The fixed amount of bus space which is | |
2392 | reserved for the CardBus bridge's IO window. | |
2393 | The default value is 256 bytes. | |
2394 | cbmemsize=nn[KMG] The fixed amount of bus space which is | |
2395 | reserved for the CardBus bridge's memory | |
2396 | window. The default value is 64 megabytes. | |
2397 | resource_alignment= | |
2398 | Format: | |
2399 | [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] | |
2400 | Specifies alignment and device to reassign | |
2401 | aligned memory resources. | |
2402 | If <order of align> is not specified, | |
2403 | PAGE_SIZE is used as alignment. | |
2404 | PCI-PCI bridge can be specified, if resource | |
2405 | windows need to be expanded. | |
2406 | ecrc= Enable/disable PCIe ECRC (transaction layer | |
2407 | end-to-end CRC checking). | |
2408 | bios: Use BIOS/firmware settings. This is the | |
2409 | the default. | |
2410 | off: Turn ECRC off | |
2411 | on: Turn ECRC on. | |
2412 | hpiosize=nn[KMG] The fixed amount of bus space which is | |
2413 | reserved for hotplug bridge's IO window. | |
2414 | Default size is 256 bytes. | |
2415 | hpmemsize=nn[KMG] The fixed amount of bus space which is | |
2416 | reserved for hotplug bridge's memory window. | |
2417 | Default size is 2 megabytes. | |
2418 | realloc= Enable/disable reallocating PCI bridge resources | |
2419 | if allocations done by BIOS are too small to | |
2420 | accommodate resources required by all child | |
2421 | devices. | |
2422 | off: Turn realloc off | |
2423 | on: Turn realloc on | |
2424 | realloc same as realloc=on | |
2425 | noari do not use PCIe ARI. | |
2426 | pcie_scan_all Scan all possible PCIe devices. Otherwise we | |
2427 | only look for one device below a PCIe downstream | |
2428 | port. | |
2429 | ||
2430 | pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power | |
2431 | Management. | |
2432 | off Disable ASPM. | |
2433 | force Enable ASPM even on devices that claim not to support it. | |
2434 | WARNING: Forcing ASPM on may cause system lockups. | |
2435 | ||
2436 | pcie_hp= [PCIE] PCI Express Hotplug driver options: | |
2437 | nomsi Do not use MSI for PCI Express Native Hotplug (this | |
2438 | makes all PCIe ports use INTx for hotplug services). | |
2439 | ||
2440 | pcie_ports= [PCIE] PCIe ports handling: | |
2441 | auto Ask the BIOS whether or not to use native PCIe services | |
2442 | associated with PCIe ports (PME, hot-plug, AER). Use | |
2443 | them only if that is allowed by the BIOS. | |
2444 | native Use native PCIe services associated with PCIe ports | |
2445 | unconditionally. | |
2446 | compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe | |
2447 | ports driver. | |
2448 | ||
2449 | pcie_pme= [PCIE,PM] Native PCIe PME signaling options: | |
2450 | nomsi Do not use MSI for native PCIe PME signaling (this makes | |
2451 | all PCIe root ports use INTx for all services). | |
2452 | ||
2453 | pcmv= [HW,PCMCIA] BadgePAD 4 | |
2454 | ||
2455 | pd. [PARIDE] | |
2456 | See Documentation/blockdev/paride.txt. | |
2457 | ||
2458 | pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at | |
2459 | boot time. | |
2460 | Format: { 0 | 1 } | |
2461 | See arch/parisc/kernel/pdc_chassis.c | |
2462 | ||
2463 | percpu_alloc= Select which percpu first chunk allocator to use. | |
2464 | Currently supported values are "embed" and "page". | |
2465 | Archs may support subset or none of the selections. | |
2466 | See comments in mm/percpu.c for details on each | |
2467 | allocator. This parameter is primarily for debugging | |
2468 | and performance comparison. | |
2469 | ||
2470 | pf. [PARIDE] | |
2471 | See Documentation/blockdev/paride.txt. | |
2472 | ||
2473 | pg. [PARIDE] | |
2474 | See Documentation/blockdev/paride.txt. | |
2475 | ||
2476 | pirq= [SMP,APIC] Manual mp-table setup | |
2477 | See Documentation/x86/i386/IO-APIC.txt. | |
2478 | ||
2479 | plip= [PPT,NET] Parallel port network link | |
2480 | Format: { parport<nr> | timid | 0 } | |
2481 | See also Documentation/parport.txt. | |
2482 | ||
2483 | pmtmr= [X86] Manual setup of pmtmr I/O Port. | |
2484 | Override pmtimer IOPort with a hex value. | |
2485 | e.g. pmtmr=0x508 | |
2486 | ||
2487 | pnp.debug=1 [PNP] | |
2488 | Enable PNP debug messages (depends on the | |
2489 | CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time | |
2490 | via /sys/module/pnp/parameters/debug. We always show | |
2491 | current resource usage; turning this on also shows | |
2492 | possible settings and some assignment information. | |
2493 | ||
2494 | pnpacpi= [ACPI] | |
2495 | { off } | |
2496 | ||
2497 | pnpbios= [ISAPNP] | |
2498 | { on | off | curr | res | no-curr | no-res } | |
2499 | ||
2500 | pnp_reserve_irq= | |
2501 | [ISAPNP] Exclude IRQs for the autoconfiguration | |
2502 | ||
2503 | pnp_reserve_dma= | |
2504 | [ISAPNP] Exclude DMAs for the autoconfiguration | |
2505 | ||
2506 | pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration | |
2507 | Ranges are in pairs (I/O port base and size). | |
2508 | ||
2509 | pnp_reserve_mem= | |
2510 | [ISAPNP] Exclude memory regions for the | |
2511 | autoconfiguration. | |
2512 | Ranges are in pairs (memory base and size). | |
2513 | ||
2514 | ports= [IP_VS_FTP] IPVS ftp helper module | |
2515 | Default is 21. | |
2516 | Up to 8 (IP_VS_APP_MAX_PORTS) ports | |
2517 | may be specified. | |
2518 | Format: <port>,<port>.... | |
2519 | ||
2520 | print-fatal-signals= | |
2521 | [KNL] debug: print fatal signals | |
2522 | ||
2523 | If enabled, warn about various signal handling | |
2524 | related application anomalies: too many signals, | |
2525 | too many POSIX.1 timers, fatal signals causing a | |
2526 | coredump - etc. | |
2527 | ||
2528 | If you hit the warning due to signal overflow, | |
2529 | you might want to try "ulimit -i unlimited". | |
2530 | ||
2531 | default: off. | |
2532 | ||
2533 | printk.always_kmsg_dump= | |
2534 | Trigger kmsg_dump for cases other than kernel oops or | |
2535 | panics | |
2536 | Format: <bool> (1/Y/y=enable, 0/N/n=disable) | |
2537 | default: disabled | |
2538 | ||
2539 | printk.time= Show timing data prefixed to each printk message line | |
2540 | Format: <bool> (1/Y/y=enable, 0/N/n=disable) | |
2541 | ||
2542 | processor.max_cstate= [HW,ACPI] | |
2543 | Limit processor to maximum C-state | |
2544 | max_cstate=9 overrides any DMI blacklist limit. | |
2545 | ||
2546 | processor.nocst [HW,ACPI] | |
2547 | Ignore the _CST method to determine C-states, | |
2548 | instead using the legacy FADT method | |
2549 | ||
2550 | profile= [KNL] Enable kernel profiling via /proc/profile | |
2551 | Format: [schedule,]<number> | |
2552 | Param: "schedule" - profile schedule points. | |
2553 | Param: <number> - step/bucket size as a power of 2 for | |
2554 | statistical time based profiling. | |
2555 | Param: "sleep" - profile D-state sleeping (millisecs). | |
2556 | Requires CONFIG_SCHEDSTATS | |
2557 | Param: "kvm" - profile VM exits. | |
2558 | ||
2559 | prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk | |
2560 | before loading. | |
2561 | See Documentation/blockdev/ramdisk.txt. | |
2562 | ||
2563 | psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to | |
2564 | probe for; one of (bare|imps|exps|lifebook|any). | |
2565 | psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports | |
2566 | per second. | |
2567 | psmouse.resetafter= [HW,MOUSE] | |
2568 | Try to reset the device after so many bad packets | |
2569 | (0 = never). | |
2570 | psmouse.resolution= | |
2571 | [HW,MOUSE] Set desired mouse resolution, in dpi. | |
2572 | psmouse.smartscroll= | |
2573 | [HW,MOUSE] Controls Logitech smartscroll autorepeat. | |
2574 | 0 = disabled, 1 = enabled (default). | |
2575 | ||
2576 | pstore.backend= Specify the name of the pstore backend to use | |
2577 | ||
2578 | pt. [PARIDE] | |
2579 | See Documentation/blockdev/paride.txt. | |
2580 | ||
2581 | pty.legacy_count= | |
2582 | [KNL] Number of legacy pty's. Overwrites compiled-in | |
2583 | default number. | |
2584 | ||
2585 | quiet [KNL] Disable most log messages | |
2586 | ||
2587 | r128= [HW,DRM] | |
2588 | ||
2589 | raid= [HW,RAID] | |
2590 | See Documentation/md.txt. | |
2591 | ||
2592 | ramdisk_blocksize= [RAM] | |
2593 | See Documentation/blockdev/ramdisk.txt. | |
2594 | ||
2595 | ramdisk_size= [RAM] Sizes of RAM disks in kilobytes | |
2596 | See Documentation/blockdev/ramdisk.txt. | |
2597 | ||
2598 | rcu_nocbs= [KNL,BOOT] | |
2599 | In kernels built with CONFIG_RCU_NOCB_CPU=y, set | |
2600 | the specified list of CPUs to be no-callback CPUs. | |
2601 | Invocation of these CPUs' RCU callbacks will | |
2602 | be offloaded to "rcuox/N" kthreads created for | |
2603 | that purpose, where "x" is "b" for RCU-bh, "p" | |
2604 | for RCU-preempt, and "s" for RCU-sched, and "N" | |
2605 | is the CPU number. This reduces OS jitter on the | |
2606 | offloaded CPUs, which can be useful for HPC and | |
2607 | ||
2608 | real-time workloads. It can also improve energy | |
2609 | efficiency for asymmetric multiprocessors. | |
2610 | ||
2611 | rcu_nocb_poll [KNL,BOOT] | |
2612 | Rather than requiring that offloaded CPUs | |
2613 | (specified by rcu_nocbs= above) explicitly | |
2614 | awaken the corresponding "rcuoN" kthreads, | |
2615 | make these kthreads poll for callbacks. | |
2616 | This improves the real-time response for the | |
2617 | offloaded CPUs by relieving them of the need to | |
2618 | wake up the corresponding kthread, but degrades | |
2619 | energy efficiency by requiring that the kthreads | |
2620 | periodically wake up to do the polling. | |
2621 | ||
2622 | rcutree.blimit= [KNL,BOOT] | |
2623 | Set maximum number of finished RCU callbacks to process | |
2624 | in one batch. | |
2625 | ||
2626 | rcutree.fanout_leaf= [KNL,BOOT] | |
2627 | Increase the number of CPUs assigned to each | |
2628 | leaf rcu_node structure. Useful for very large | |
2629 | systems. | |
2630 | ||
2631 | rcutree.jiffies_till_first_fqs= [KNL,BOOT] | |
2632 | Set delay from grace-period initialization to | |
2633 | first attempt to force quiescent states. | |
2634 | Units are jiffies, minimum value is zero, | |
2635 | and maximum value is HZ. | |
2636 | ||
2637 | rcutree.jiffies_till_next_fqs= [KNL,BOOT] | |
2638 | Set delay between subsequent attempts to force | |
2639 | quiescent states. Units are jiffies, minimum | |
2640 | value is one, and maximum value is HZ. | |
2641 | ||
2642 | rcutree.qhimark= [KNL,BOOT] | |
2643 | Set threshold of queued | |
2644 | RCU callbacks over which batch limiting is disabled. | |
2645 | ||
2646 | rcutree.qlowmark= [KNL,BOOT] | |
2647 | Set threshold of queued RCU callbacks below which | |
2648 | batch limiting is re-enabled. | |
2649 | ||
2650 | rcutree.rcu_cpu_stall_suppress= [KNL,BOOT] | |
2651 | Suppress RCU CPU stall warning messages. | |
2652 | ||
2653 | rcutree.rcu_cpu_stall_timeout= [KNL,BOOT] | |
2654 | Set timeout for RCU CPU stall warning messages. | |
2655 | ||
2656 | rcutree.rcu_idle_gp_delay= [KNL,BOOT] | |
2657 | Set wakeup interval for idle CPUs that have | |
2658 | RCU callbacks (RCU_FAST_NO_HZ=y). | |
2659 | ||
2660 | rcutree.rcu_idle_lazy_gp_delay= [KNL,BOOT] | |
2661 | Set wakeup interval for idle CPUs that have | |
2662 | only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). | |
2663 | Lazy RCU callbacks are those which RCU can | |
2664 | prove do nothing more than free memory. | |
2665 | ||
2666 | rcutorture.fqs_duration= [KNL,BOOT] | |
2667 | Set duration of force_quiescent_state bursts. | |
2668 | ||
2669 | rcutorture.fqs_holdoff= [KNL,BOOT] | |
2670 | Set holdoff time within force_quiescent_state bursts. | |
2671 | ||
2672 | rcutorture.fqs_stutter= [KNL,BOOT] | |
2673 | Set wait time between force_quiescent_state bursts. | |
2674 | ||
2675 | rcutorture.irqreader= [KNL,BOOT] | |
2676 | Test RCU readers from irq handlers. | |
2677 | ||
2678 | rcutorture.n_barrier_cbs= [KNL,BOOT] | |
2679 | Set callbacks/threads for rcu_barrier() testing. | |
2680 | ||
2681 | rcutorture.nfakewriters= [KNL,BOOT] | |
2682 | Set number of concurrent RCU writers. These just | |
2683 | stress RCU, they don't participate in the actual | |
2684 | test, hence the "fake". | |
2685 | ||
2686 | rcutorture.nreaders= [KNL,BOOT] | |
2687 | Set number of RCU readers. | |
2688 | ||
2689 | rcutorture.onoff_holdoff= [KNL,BOOT] | |
2690 | Set time (s) after boot for CPU-hotplug testing. | |
2691 | ||
2692 | rcutorture.onoff_interval= [KNL,BOOT] | |
2693 | Set time (s) between CPU-hotplug operations, or | |
2694 | zero to disable CPU-hotplug testing. | |
2695 | ||
2696 | rcutorture.shuffle_interval= [KNL,BOOT] | |
2697 | Set task-shuffle interval (s). Shuffling tasks | |
2698 | allows some CPUs to go into dyntick-idle mode | |
2699 | during the rcutorture test. | |
2700 | ||
2701 | rcutorture.shutdown_secs= [KNL,BOOT] | |
2702 | Set time (s) after boot system shutdown. This | |
2703 | is useful for hands-off automated testing. | |
2704 | ||
2705 | rcutorture.stall_cpu= [KNL,BOOT] | |
2706 | Duration of CPU stall (s) to test RCU CPU stall | |
2707 | warnings, zero to disable. | |
2708 | ||
2709 | rcutorture.stall_cpu_holdoff= [KNL,BOOT] | |
2710 | Time to wait (s) after boot before inducing stall. | |
2711 | ||
2712 | rcutorture.stat_interval= [KNL,BOOT] | |
2713 | Time (s) between statistics printk()s. | |
2714 | ||
2715 | rcutorture.stutter= [KNL,BOOT] | |
2716 | Time (s) to stutter testing, for example, specifying | |
2717 | five seconds causes the test to run for five seconds, | |
2718 | wait for five seconds, and so on. This tests RCU's | |
2719 | ability to transition abruptly to and from idle. | |
2720 | ||
2721 | rcutorture.test_boost= [KNL,BOOT] | |
2722 | Test RCU priority boosting? 0=no, 1=maybe, 2=yes. | |
2723 | "Maybe" means test if the RCU implementation | |
2724 | under test support RCU priority boosting. | |
2725 | ||
2726 | rcutorture.test_boost_duration= [KNL,BOOT] | |
2727 | Duration (s) of each individual boost test. | |
2728 | ||
2729 | rcutorture.test_boost_interval= [KNL,BOOT] | |
2730 | Interval (s) between each boost test. | |
2731 | ||
2732 | rcutorture.test_no_idle_hz= [KNL,BOOT] | |
2733 | Test RCU's dyntick-idle handling. See also the | |
2734 | rcutorture.shuffle_interval parameter. | |
2735 | ||
2736 | rcutorture.torture_type= [KNL,BOOT] | |
2737 | Specify the RCU implementation to test. | |
2738 | ||
2739 | rcutorture.verbose= [KNL,BOOT] | |
2740 | Enable additional printk() statements. | |
2741 | ||
2742 | rdinit= [KNL] | |
2743 | Format: <full_path> | |
2744 | Run specified binary instead of /init from the ramdisk, | |
2745 | used for early userspace startup. See initrd. | |
2746 | ||
2747 | reboot= [KNL] | |
2748 | Format (x86 or x86_64): | |
2749 | [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ | |
2750 | [[,]s[mp]#### \ | |
2751 | [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ | |
2752 | [[,]f[orce] | |
2753 | Where reboot_mode is one of warm (soft) or cold (hard) or gpio, | |
2754 | reboot_type is one of bios, acpi, kbd, triple, efi, or pci, | |
2755 | reboot_force is either force or not specified, | |
2756 | reboot_cpu is s[mp]#### with #### being the processor | |
2757 | to be used for rebooting. | |
2758 | ||
2759 | relax_domain_level= | |
2760 | [KNL, SMP] Set scheduler's default relax_domain_level. | |
2761 | See Documentation/cgroups/cpusets.txt. | |
2762 | ||
2763 | reserve= [KNL,BUGS] Force the kernel to ignore some iomem area | |
2764 | ||
2765 | reservetop= [X86-32] | |
2766 | Format: nn[KMG] | |
2767 | Reserves a hole at the top of the kernel virtual | |
2768 | address space. | |
2769 | ||
2770 | reservelow= [X86] | |
2771 | Format: nn[K] | |
2772 | Set the amount of memory to reserve for BIOS at | |
2773 | the bottom of the address space. | |
2774 | ||
2775 | reset_devices [KNL] Force drivers to reset the underlying device | |
2776 | during initialization. | |
2777 | ||
2778 | resume= [SWSUSP] | |
2779 | Specify the partition device for software suspend | |
2780 | Format: | |
2781 | {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>} | |
2782 | ||
2783 | resume_offset= [SWSUSP] | |
2784 | Specify the offset from the beginning of the partition | |
2785 | given by "resume=" at which the swap header is located, | |
2786 | in <PAGE_SIZE> units (needed only for swap files). | |
2787 | See Documentation/power/swsusp-and-swap-files.txt | |
2788 | ||
2789 | resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to | |
2790 | read the resume files | |
2791 | ||
2792 | resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up. | |
2793 | Useful for devices that are detected asynchronously | |
2794 | (e.g. USB and MMC devices). | |
2795 | ||
2796 | hibernate= [HIBERNATION] | |
2797 | noresume Don't check if there's a hibernation image | |
2798 | present during boot. | |
2799 | nocompress Don't compress/decompress hibernation images. | |
2800 | ||
2801 | retain_initrd [RAM] Keep initrd memory after extraction | |
2802 | ||
2803 | rhash_entries= [KNL,NET] | |
2804 | Set number of hash buckets for route cache | |
2805 | ||
2806 | riscom8= [HW,SERIAL] | |
2807 | Format: <io_board1>[,<io_board2>[,...<io_boardN>]] | |
2808 | ||
2809 | ro [KNL] Mount root device read-only on boot | |
2810 | ||
2811 | root= [KNL] Root filesystem | |
2812 | See name_to_dev_t comment in init/do_mounts.c. | |
2813 | ||
2814 | rootdelay= [KNL] Delay (in seconds) to pause before attempting to | |
2815 | mount the root filesystem | |
2816 | ||
2817 | rootflags= [KNL] Set root filesystem mount option string | |
2818 | ||
2819 | rootfstype= [KNL] Set root filesystem type | |
2820 | ||
2821 | rootwait [KNL] Wait (indefinitely) for root device to show up. | |
2822 | Useful for devices that are detected asynchronously | |
2823 | (e.g. USB and MMC devices). | |
2824 | ||
2825 | rproc_mem=nn[KMG][@address] | |
2826 | [KNL,ARM,CMA] Remoteproc physical memory block. | |
2827 | Memory area to be used by remote processor image, | |
2828 | managed by CMA. | |
2829 | ||
2830 | rw [KNL] Mount root device read-write on boot | |
2831 | ||
2832 | S [KNL] Run init in single mode | |
2833 | ||
2834 | sa1100ir [NET] | |
2835 | See drivers/net/irda/sa1100_ir.c. | |
2836 | ||
2837 | sbni= [NET] Granch SBNI12 leased line adapter | |
2838 | ||
2839 | sched_debug [KNL] Enables verbose scheduler debug messages. | |
2840 | ||
2841 | skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate | |
2842 | xtime_lock contention on larger systems, and/or RCU lock | |
2843 | contention on all systems with CONFIG_MAXSMP set. | |
2844 | Format: { "0" | "1" } | |
2845 | 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" | |
2846 | 1 -- enable. | |
2847 | Note: increases power consumption, thus should only be | |
2848 | enabled if running jitter sensitive (HPC/RT) workloads. | |
2849 | ||
2850 | security= [SECURITY] Choose a security module to enable at boot. | |
2851 | If this boot parameter is not specified, only the first | |
2852 | security module asking for security registration will be | |
2853 | loaded. An invalid security module name will be treated | |
2854 | as if no module has been chosen. | |
2855 | ||
2856 | selinux= [SELINUX] Disable or enable SELinux at boot time. | |
2857 | Format: { "0" | "1" } | |
2858 | See security/selinux/Kconfig help text. | |
2859 | 0 -- disable. | |
2860 | 1 -- enable. | |
2861 | Default value is set via kernel config option. | |
2862 | If enabled at boot time, /selinux/disable can be used | |
2863 | later to disable prior to initial policy load. | |
2864 | ||
2865 | apparmor= [APPARMOR] Disable or enable AppArmor at boot time | |
2866 | Format: { "0" | "1" } | |
2867 | See security/apparmor/Kconfig help text | |
2868 | 0 -- disable. | |
2869 | 1 -- enable. | |
2870 | Default value is set via kernel config option. | |
2871 | ||
2872 | serialnumber [BUGS=X86-32] | |
2873 | ||
2874 | shapers= [NET] | |
2875 | Maximal number of shapers. | |
2876 | ||
2877 | show_msr= [x86] show boot-time MSR settings | |
2878 | Format: { <integer> } | |
2879 | Show boot-time (BIOS-initialized) MSR settings. | |
2880 | The parameter means the number of CPUs to show, | |
2881 | for example 1 means boot CPU only. | |
2882 | ||
2883 | simeth= [IA-64] | |
2884 | simscsi= | |
2885 | ||
2886 | slram= [HW,MTD] | |
2887 | ||
2888 | slab_max_order= [MM, SLAB] | |
2889 | Determines the maximum allowed order for slabs. | |
2890 | A high setting may cause OOMs due to memory | |
2891 | fragmentation. Defaults to 1 for systems with | |
2892 | more than 32MB of RAM, 0 otherwise. | |
2893 | ||
2894 | slub_debug[=options[,slabs]] [MM, SLUB] | |
2895 | Enabling slub_debug allows one to determine the | |
2896 | culprit if slab objects become corrupted. Enabling | |
2897 | slub_debug can create guard zones around objects and | |
2898 | may poison objects when not in use. Also tracks the | |
2899 | last alloc / free. For more information see | |
2900 | Documentation/vm/slub.txt. | |
2901 | ||
2902 | slub_max_order= [MM, SLUB] | |
2903 | Determines the maximum allowed order for slabs. | |
2904 | A high setting may cause OOMs due to memory | |
2905 | fragmentation. For more information see | |
2906 | Documentation/vm/slub.txt. | |
2907 | ||
2908 | slub_min_objects= [MM, SLUB] | |
2909 | The minimum number of objects per slab. SLUB will | |
2910 | increase the slab order up to slub_max_order to | |
2911 | generate a sufficiently large slab able to contain | |
2912 | the number of objects indicated. The higher the number | |
2913 | of objects the smaller the overhead of tracking slabs | |
2914 | and the less frequently locks need to be acquired. | |
2915 | For more information see Documentation/vm/slub.txt. | |
2916 | ||
2917 | slub_min_order= [MM, SLUB] | |
2918 | Determines the minimum page order for slabs. Must be | |
2919 | lower than slub_max_order. | |
2920 | For more information see Documentation/vm/slub.txt. | |
2921 | ||
2922 | slub_nomerge [MM, SLUB] | |
2923 | Disable merging of slabs with similar size. May be | |
2924 | necessary if there is some reason to distinguish | |
2925 | allocs to different slabs. Debug options disable | |
2926 | merging on their own. | |
2927 | For more information see Documentation/vm/slub.txt. | |
2928 | ||
2929 | smart2= [HW] | |
2930 | Format: <io1>[,<io2>[,...,<io8>]] | |
2931 | ||
2932 | smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices | |
2933 | smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port | |
2934 | smsc-ircc2.ircc_sir= [HW] SIR base I/O port | |
2935 | smsc-ircc2.ircc_fir= [HW] FIR base I/O port | |
2936 | smsc-ircc2.ircc_irq= [HW] IRQ line | |
2937 | smsc-ircc2.ircc_dma= [HW] DMA channel | |
2938 | smsc-ircc2.ircc_transceiver= [HW] Transceiver type: | |
2939 | 0: Toshiba Satellite 1800 (GP data pin select) | |
2940 | 1: Fast pin select (default) | |
2941 | 2: ATC IRMode | |
2942 | ||
2943 | softlockup_panic= | |
2944 | [KNL] Should the soft-lockup detector generate panics. | |
2945 | Format: <integer> | |
2946 | ||
2947 | sonypi.*= [HW] Sony Programmable I/O Control Device driver | |
2948 | See Documentation/laptops/sonypi.txt | |
2949 | ||
2950 | specialix= [HW,SERIAL] Specialix multi-serial port adapter | |
2951 | See Documentation/serial/specialix.txt. | |
2952 | ||
2953 | spia_io_base= [HW,MTD] | |
2954 | spia_fio_base= | |
2955 | spia_pedr= | |
2956 | spia_peddr= | |
2957 | ||
2958 | stacktrace [FTRACE] | |
2959 | Enabled the stack tracer on boot up. | |
2960 | ||
2961 | stacktrace_filter=[function-list] | |
2962 | [FTRACE] Limit the functions that the stack tracer | |
2963 | will trace at boot up. function-list is a comma separated | |
2964 | list of functions. This list can be changed at run | |
2965 | time by the stack_trace_filter file in the debugfs | |
2966 | tracing directory. Note, this enables stack tracing | |
2967 | and the stacktrace above is not needed. | |
2968 | ||
2969 | sti= [PARISC,HW] | |
2970 | Format: <num> | |
2971 | Set the STI (builtin display/keyboard on the HP-PARISC | |
2972 | machines) console (graphic card) which should be used | |
2973 | as the initial boot-console. | |
2974 | See also comment in drivers/video/console/sticore.c. | |
2975 | ||
2976 | sti_font= [HW] | |
2977 | See comment in drivers/video/console/sticore.c. | |
2978 | ||
2979 | stifb= [HW] | |
2980 | Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] | |
2981 | ||
2982 | sunrpc.min_resvport= | |
2983 | sunrpc.max_resvport= | |
2984 | [NFS,SUNRPC] | |
2985 | SunRPC servers often require that client requests | |
2986 | originate from a privileged port (i.e. a port in the | |
2987 | range 0 < portnr < 1024). | |
2988 | An administrator who wishes to reserve some of these | |
2989 | ports for other uses may adjust the range that the | |
2990 | kernel's sunrpc client considers to be privileged | |
2991 | using these two parameters to set the minimum and | |
2992 | maximum port values. | |
2993 | ||
2994 | sunrpc.pool_mode= | |
2995 | [NFS] | |
2996 | Control how the NFS server code allocates CPUs to | |
2997 | service thread pools. Depending on how many NICs | |
2998 | you have and where their interrupts are bound, this | |
2999 | option will affect which CPUs will do NFS serving. | |
3000 | Note: this parameter cannot be changed while the | |
3001 | NFS server is running. | |
3002 | ||
3003 | auto the server chooses an appropriate mode | |
3004 | automatically using heuristics | |
3005 | global a single global pool contains all CPUs | |
3006 | percpu one pool for each CPU | |
3007 | pernode one pool for each NUMA node (equivalent | |
3008 | to global on non-NUMA machines) | |
3009 | ||
3010 | sunrpc.tcp_slot_table_entries= | |
3011 | sunrpc.udp_slot_table_entries= | |
3012 | [NFS,SUNRPC] | |
3013 | Sets the upper limit on the number of simultaneous | |
3014 | RPC calls that can be sent from the client to a | |
3015 | server. Increasing these values may allow you to | |
3016 | improve throughput, but will also increase the | |
3017 | amount of memory reserved for use by the client. | |
3018 | ||
3019 | swapaccount=[0|1] | |
3020 | [KNL] Enable accounting of swap in memory resource | |
3021 | controller if no parameter or 1 is given or disable | |
3022 | it if 0 is given (See Documentation/cgroups/memory.txt) | |
3023 | ||
3024 | swiotlb= [IA-64] Number of I/O TLB slabs | |
3025 | ||
3026 | switches= [HW,M68k] | |
3027 | ||
3028 | sysfs.deprecated=0|1 [KNL] | |
3029 | Enable/disable old style sysfs layout for old udev | |
3030 | on older distributions. When this option is enabled | |
3031 | very new udev will not work anymore. When this option | |
3032 | is disabled (or CONFIG_SYSFS_DEPRECATED not compiled) | |
3033 | in older udev will not work anymore. | |
3034 | Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in | |
3035 | the kernel configuration. | |
3036 | ||
3037 | sysrq_always_enabled | |
3038 | [KNL] | |
3039 | Ignore sysrq setting - this boot parameter will | |
3040 | neutralize any effect of /proc/sys/kernel/sysrq. | |
3041 | Useful for debugging. | |
3042 | ||
3043 | tdfx= [HW,DRM] | |
3044 | ||
3045 | test_suspend= [SUSPEND] | |
3046 | Specify "mem" (for Suspend-to-RAM) or "standby" (for | |
3047 | standby suspend) as the system sleep state to briefly | |
3048 | enter during system startup. The system is woken from | |
3049 | this state using a wakeup-capable RTC alarm. | |
3050 | ||
3051 | thash_entries= [KNL,NET] | |
3052 | Set number of hash buckets for TCP connection | |
3053 | ||
3054 | thermal.act= [HW,ACPI] | |
3055 | -1: disable all active trip points in all thermal zones | |
3056 | <degrees C>: override all lowest active trip points | |
3057 | ||
3058 | thermal.crt= [HW,ACPI] | |
3059 | -1: disable all critical trip points in all thermal zones | |
3060 | <degrees C>: override all critical trip points | |
3061 | ||
3062 | thermal.nocrt= [HW,ACPI] | |
3063 | Set to disable actions on ACPI thermal zone | |
3064 | critical and hot trip points. | |
3065 | ||
3066 | thermal.off= [HW,ACPI] | |
3067 | 1: disable ACPI thermal control | |
3068 | ||
3069 | thermal.psv= [HW,ACPI] | |
3070 | -1: disable all passive trip points | |
3071 | <degrees C>: override all passive trip points to this | |
3072 | value | |
3073 | ||
3074 | thermal.tzp= [HW,ACPI] | |
3075 | Specify global default ACPI thermal zone polling rate | |
3076 | <deci-seconds>: poll all this frequency | |
3077 | 0: no polling (default) | |
3078 | ||
3079 | threadirqs [KNL] | |
3080 | Force threading of all interrupt handlers except those | |
3081 | marked explicitly IRQF_NO_THREAD. | |
3082 | ||
3083 | tmem [KNL,XEN] | |
3084 | Enable the Transcendent memory driver if built-in. | |
3085 | ||
3086 | tmem.cleancache=0|1 [KNL, XEN] | |
3087 | Default is on (1). Disable the usage of the cleancache | |
3088 | API to send anonymous pages to the hypervisor. | |
3089 | ||
3090 | tmem.frontswap=0|1 [KNL, XEN] | |
3091 | Default is on (1). Disable the usage of the frontswap | |
3092 | API to send swap pages to the hypervisor. If disabled | |
3093 | the selfballooning and selfshrinking are force disabled. | |
3094 | ||
3095 | tmem.selfballooning=0|1 [KNL, XEN] | |
3096 | Default is on (1). Disable the driving of swap pages | |
3097 | to the hypervisor. | |
3098 | ||
3099 | tmem.selfshrinking=0|1 [KNL, XEN] | |
3100 | Default is on (1). Partial swapoff that immediately | |
3101 | transfers pages from Xen hypervisor back to the | |
3102 | kernel based on different criteria. | |
3103 | ||
3104 | topology= [S390] | |
3105 | Format: {off | on} | |
3106 | Specify if the kernel should make use of the cpu | |
3107 | topology information if the hardware supports this. | |
3108 | The scheduler will make use of this information and | |
3109 | e.g. base its process migration decisions on it. | |
3110 | Default is on. | |
3111 | ||
3112 | tp720= [HW,PS2] | |
3113 | ||
3114 | tpm_suspend_pcr=[HW,TPM] | |
3115 | Format: integer pcr id | |
3116 | Specify that at suspend time, the tpm driver | |
3117 | should extend the specified pcr with zeros, | |
3118 | as a workaround for some chips which fail to | |
3119 | flush the last written pcr on TPM_SaveState. | |
3120 | This will guarantee that all the other pcrs | |
3121 | are saved. | |
3122 | ||
3123 | trace_buf_size=nn[KMG] | |
3124 | [FTRACE] will set tracing buffer size. | |
3125 | ||
3126 | trace_event=[event-list] | |
3127 | [FTRACE] Set and start specified trace events in order | |
3128 | to facilitate early boot debugging. | |
3129 | See also Documentation/trace/events.txt | |
3130 | ||
3131 | trace_options=[option-list] | |
3132 | [FTRACE] Enable or disable tracer options at boot. | |
3133 | The option-list is a comma delimited list of options | |
3134 | that can be enabled or disabled just as if you were | |
3135 | to echo the option name into | |
3136 | ||
3137 | /sys/kernel/debug/tracing/trace_options | |
3138 | ||
3139 | For example, to enable stacktrace option (to dump the | |
3140 | stack trace of each event), add to the command line: | |
3141 | ||
3142 | trace_options=stacktrace | |
3143 | ||
3144 | See also Documentation/trace/ftrace.txt "trace options" | |
3145 | section. | |
3146 | ||
3147 | traceoff_on_warning | |
3148 | [FTRACE] enable this option to disable tracing when a | |
3149 | warning is hit. This turns off "tracing_on". Tracing can | |
3150 | be enabled again by echoing '1' into the "tracing_on" | |
3151 | file located in /sys/kernel/debug/tracing/ | |
3152 | ||
3153 | This option is useful, as it disables the trace before | |
3154 | the WARNING dump is called, which prevents the trace to | |
3155 | be filled with content caused by the warning output. | |
3156 | ||
3157 | This option can also be set at run time via the sysctl | |
3158 | option: kernel/traceoff_on_warning | |
3159 | ||
3160 | transparent_hugepage= | |
3161 | [KNL] | |
3162 | Format: [always|madvise|never] | |
3163 | Can be used to control the default behavior of the system | |
3164 | with respect to transparent hugepages. | |
3165 | See Documentation/vm/transhuge.txt for more details. | |
3166 | ||
3167 | tsc= Disable clocksource stability checks for TSC. | |
3168 | Format: <string> | |
3169 | [x86] reliable: mark tsc clocksource as reliable, this | |
3170 | disables clocksource verification at runtime, as well | |
3171 | as the stability checks done at bootup. Used to enable | |
3172 | high-resolution timer mode on older hardware, and in | |
3173 | virtualized environment. | |
3174 | [x86] noirqtime: Do not use TSC to do irq accounting. | |
3175 | Used to run time disable IRQ_TIME_ACCOUNTING on any | |
3176 | platforms where RDTSC is slow and this accounting | |
3177 | can add overhead. | |
3178 | ||
3179 | turbografx.map[2|3]= [HW,JOY] | |
3180 | TurboGraFX parallel port interface | |
3181 | Format: | |
3182 | <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> | |
3183 | See also Documentation/input/joystick-parport.txt | |
3184 | ||
3185 | udbg-immortal [PPC] When debugging early kernel crashes that | |
3186 | happen after console_init() and before a proper | |
3187 | console driver takes over, this boot options might | |
3188 | help "seeing" what's going on. | |
3189 | ||
3190 | uhash_entries= [KNL,NET] | |
3191 | Set number of hash buckets for UDP/UDP-Lite connections | |
3192 | ||
3193 | uhci-hcd.ignore_oc= | |
3194 | [USB] Ignore overcurrent events (default N). | |
3195 | Some badly-designed motherboards generate lots of | |
3196 | bogus events, for ports that aren't wired to | |
3197 | anything. Set this parameter to avoid log spamming. | |
3198 | Note that genuine overcurrent events won't be | |
3199 | reported either. | |
3200 | ||
3201 | unknown_nmi_panic | |
3202 | [X86] Cause panic on unknown NMI. | |
3203 | ||
3204 | usbcore.authorized_default= | |
3205 | [USB] Default USB device authorization: | |
3206 | (default -1 = authorized except for wireless USB, | |
3207 | 0 = not authorized, 1 = authorized) | |
3208 | ||
3209 | usbcore.autosuspend= | |
3210 | [USB] The autosuspend time delay (in seconds) used | |
3211 | for newly-detected USB devices (default 2). This | |
3212 | is the time required before an idle device will be | |
3213 | autosuspended. Devices for which the delay is set | |
3214 | to a negative value won't be autosuspended at all. | |
3215 | ||
3216 | usbcore.usbfs_snoop= | |
3217 | [USB] Set to log all usbfs traffic (default 0 = off). | |
3218 | ||
3219 | usbcore.blinkenlights= | |
3220 | [USB] Set to cycle leds on hubs (default 0 = off). | |
3221 | ||
3222 | usbcore.old_scheme_first= | |
3223 | [USB] Start with the old device initialization | |
3224 | scheme (default 0 = off). | |
3225 | ||
3226 | usbcore.usbfs_memory_mb= | |
3227 | [USB] Memory limit (in MB) for buffers allocated by | |
3228 | usbfs (default = 16, 0 = max = 2047). | |
3229 | ||
3230 | usbcore.use_both_schemes= | |
3231 | [USB] Try the other device initialization scheme | |
3232 | if the first one fails (default 1 = enabled). | |
3233 | ||
3234 | usbcore.initial_descriptor_timeout= | |
3235 | [USB] Specifies timeout for the initial 64-byte | |
3236 | USB_REQ_GET_DESCRIPTOR request in milliseconds | |
3237 | (default 5000 = 5.0 seconds). | |
3238 | ||
3239 | usbhid.mousepoll= | |
3240 | [USBHID] The interval which mice are to be polled at. | |
3241 | ||
3242 | usb-storage.delay_use= | |
3243 | [UMS] The delay in seconds before a new device is | |
3244 | scanned for Logical Units (default 5). | |
3245 | ||
3246 | usb-storage.quirks= | |
3247 | [UMS] A list of quirks entries to supplement or | |
3248 | override the built-in unusual_devs list. List | |
3249 | entries are separated by commas. Each entry has | |
3250 | the form VID:PID:Flags where VID and PID are Vendor | |
3251 | and Product ID values (4-digit hex numbers) and | |
3252 | Flags is a set of characters, each corresponding | |
3253 | to a common usb-storage quirk flag as follows: | |
3254 | a = SANE_SENSE (collect more than 18 bytes | |
3255 | of sense data); | |
3256 | b = BAD_SENSE (don't collect more than 18 | |
3257 | bytes of sense data); | |
3258 | c = FIX_CAPACITY (decrease the reported | |
3259 | device capacity by one sector); | |
3260 | d = NO_READ_DISC_INFO (don't use | |
3261 | READ_DISC_INFO command); | |
3262 | e = NO_READ_CAPACITY_16 (don't use | |
3263 | READ_CAPACITY_16 command); | |
3264 | h = CAPACITY_HEURISTICS (decrease the | |
3265 | reported device capacity by one | |
3266 | sector if the number is odd); | |
3267 | i = IGNORE_DEVICE (don't bind to this | |
3268 | device); | |
3269 | l = NOT_LOCKABLE (don't try to lock and | |
3270 | unlock ejectable media); | |
3271 | m = MAX_SECTORS_64 (don't transfer more | |
3272 | than 64 sectors = 32 KB at a time); | |
3273 | n = INITIAL_READ10 (force a retry of the | |
3274 | initial READ(10) command); | |
3275 | o = CAPACITY_OK (accept the capacity | |
3276 | reported by the device); | |
3277 | p = WRITE_CACHE (the device cache is ON | |
3278 | by default); | |
3279 | r = IGNORE_RESIDUE (the device reports | |
3280 | bogus residue values); | |
3281 | s = SINGLE_LUN (the device has only one | |
3282 | Logical Unit); | |
3283 | w = NO_WP_DETECT (don't test whether the | |
3284 | medium is write-protected). | |
3285 | Example: quirks=0419:aaf5:rl,0421:0433:rc | |
3286 | ||
3287 | user_debug= [KNL,ARM] | |
3288 | Format: <int> | |
3289 | See arch/arm/Kconfig.debug help text. | |
3290 | 1 - undefined instruction events | |
3291 | 2 - system calls | |
3292 | 4 - invalid data aborts | |
3293 | 8 - SIGSEGV faults | |
3294 | 16 - SIGBUS faults | |
3295 | Example: user_debug=31 | |
3296 | ||
3297 | userpte= | |
3298 | [X86] Flags controlling user PTE allocations. | |
3299 | ||
3300 | nohigh = do not allocate PTE pages in | |
3301 | HIGHMEM regardless of setting | |
3302 | of CONFIG_HIGHPTE. | |
3303 | ||
3304 | vdso= [X86,SH] | |
3305 | vdso=2: enable compat VDSO (default with COMPAT_VDSO) | |
3306 | vdso=1: enable VDSO (default) | |
3307 | vdso=0: disable VDSO mapping | |
3308 | ||
3309 | vdso32= [X86] | |
3310 | vdso32=2: enable compat VDSO (default with COMPAT_VDSO) | |
3311 | vdso32=1: enable 32-bit VDSO (default) | |
3312 | vdso32=0: disable 32-bit VDSO mapping | |
3313 | ||
3314 | vector= [IA-64,SMP] | |
3315 | vector=percpu: enable percpu vector domain | |
3316 | ||
3317 | video= [FB] Frame buffer configuration | |
3318 | See Documentation/fb/modedb.txt. | |
3319 | ||
3320 | video.brightness_switch_enabled= [0,1] | |
3321 | If set to 1, on receiving an ACPI notify event | |
3322 | generated by hotkey, video driver will adjust brightness | |
3323 | level and then send out the event to user space through | |
3324 | the allocated input device; If set to 0, video driver | |
3325 | will only send out the event without touching backlight | |
3326 | brightness level. | |
3327 | default: 1 | |
3328 | ||
3329 | virtio_mmio.device= | |
3330 | [VMMIO] Memory mapped virtio (platform) device. | |
3331 | ||
3332 | <size>@<baseaddr>:<irq>[:<id>] | |
3333 | where: | |
3334 | <size> := size (can use standard suffixes | |
3335 | like K, M and G) | |
3336 | <baseaddr> := physical base address | |
3337 | <irq> := interrupt number (as passed to | |
3338 | request_irq()) | |
3339 | <id> := (optional) platform device id | |
3340 | example: | |
3341 | virtio_mmio.device=1K@0x100b0000:48:7 | |
3342 | ||
3343 | Can be used multiple times for multiple devices. | |
3344 | ||
3345 | vga= [BOOT,X86-32] Select a particular video mode | |
3346 | See Documentation/x86/boot.txt and | |
3347 | Documentation/svga.txt. | |
3348 | Use vga=ask for menu. | |
3349 | This is actually a boot loader parameter; the value is | |
3350 | passed to the kernel using a special protocol. | |
3351 | ||
3352 | vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact | |
3353 | size of <nn>. This can be used to increase the | |
3354 | minimum size (128MB on x86). It can also be used to | |
3355 | decrease the size and leave more room for directly | |
3356 | mapped kernel RAM. | |
3357 | ||
3358 | vmhalt= [KNL,S390] Perform z/VM CP command after system halt. | |
3359 | Format: <command> | |
3360 | ||
3361 | vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. | |
3362 | Format: <command> | |
3363 | ||
3364 | vmpoff= [KNL,S390] Perform z/VM CP command after power off. | |
3365 | Format: <command> | |
3366 | ||
3367 | vsyscall= [X86-64] | |
3368 | Controls the behavior of vsyscalls (i.e. calls to | |
3369 | fixed addresses of 0xffffffffff600x00 from legacy | |
3370 | code). Most statically-linked binaries and older | |
3371 | versions of glibc use these calls. Because these | |
3372 | functions are at fixed addresses, they make nice | |
3373 | targets for exploits that can control RIP. | |
3374 | ||
3375 | emulate [default] Vsyscalls turn into traps and are | |
3376 | emulated reasonably safely. | |
3377 | ||
3378 | native Vsyscalls are native syscall instructions. | |
3379 | This is a little bit faster than trapping | |
3380 | and makes a few dynamic recompilers work | |
3381 | better than they would in emulation mode. | |
3382 | It also makes exploits much easier to write. | |
3383 | ||
3384 | none Vsyscalls don't work at all. This makes | |
3385 | them quite hard to use for exploits but | |
3386 | might break your system. | |
3387 | ||
3388 | vt.color= [VT] Default text color. | |
3389 | Format: 0xYX, X = foreground, Y = background. | |
3390 | Default: 0x07 = light gray on black. | |
3391 | ||
3392 | vt.cur_default= [VT] Default cursor shape. | |
3393 | Format: 0xCCBBAA, where AA, BB, and CC are the same as | |
3394 | the parameters of the <Esc>[?A;B;Cc escape sequence; | |
3395 | see VGA-softcursor.txt. Default: 2 = underline. | |
3396 | ||
3397 | vt.default_blu= [VT] | |
3398 | Format: <blue0>,<blue1>,<blue2>,...,<blue15> | |
3399 | Change the default blue palette of the console. | |
3400 | This is a 16-member array composed of values | |
3401 | ranging from 0-255. | |
3402 | ||
3403 | vt.default_grn= [VT] | |
3404 | Format: <green0>,<green1>,<green2>,...,<green15> | |
3405 | Change the default green palette of the console. | |
3406 | This is a 16-member array composed of values | |
3407 | ranging from 0-255. | |
3408 | ||
3409 | vt.default_red= [VT] | |
3410 | Format: <red0>,<red1>,<red2>,...,<red15> | |
3411 | Change the default red palette of the console. | |
3412 | This is a 16-member array composed of values | |
3413 | ranging from 0-255. | |
3414 | ||
3415 | vt.default_utf8= | |
3416 | [VT] | |
3417 | Format=<0|1> | |
3418 | Set system-wide default UTF-8 mode for all tty's. | |
3419 | Default is 1, i.e. UTF-8 mode is enabled for all | |
3420 | newly opened terminals. | |
3421 | ||
3422 | vt.global_cursor_default= | |
3423 | [VT] | |
3424 | Format=<-1|0|1> | |
3425 | Set system-wide default for whether a cursor | |
3426 | is shown on new VTs. Default is -1, | |
3427 | i.e. cursors will be created by default unless | |
3428 | overridden by individual drivers. 0 will hide | |
3429 | cursors, 1 will display them. | |
3430 | ||
3431 | vt.italic= [VT] Default color for italic text; 0-15. | |
3432 | Default: 2 = green. | |
3433 | ||
3434 | vt.underline= [VT] Default color for underlined text; 0-15. | |
3435 | Default: 3 = cyan. | |
3436 | ||
3437 | watchdog timers [HW,WDT] For information on watchdog timers, | |
3438 | see Documentation/watchdog/watchdog-parameters.txt | |
3439 | or other driver-specific files in the | |
3440 | Documentation/watchdog/ directory. | |
3441 | ||
3442 | workqueue.disable_numa | |
3443 | By default, all work items queued to unbound | |
3444 | workqueues are affine to the NUMA nodes they're | |
3445 | issued on, which results in better behavior in | |
3446 | general. If NUMA affinity needs to be disabled for | |
3447 | whatever reason, this option can be used. Note | |
3448 | that this also can be controlled per-workqueue for | |
3449 | workqueues visible under /sys/bus/workqueue/. | |
3450 | ||
3451 | workqueue.power_efficient | |
3452 | Per-cpu workqueues are generally preferred because | |
3453 | they show better performance thanks to cache | |
3454 | locality; unfortunately, per-cpu workqueues tend to | |
3455 | be more power hungry than unbound workqueues. | |
3456 | ||
3457 | Enabling this makes the per-cpu workqueues which | |
3458 | were observed to contribute significantly to power | |
3459 | consumption unbound, leading to measurably lower | |
3460 | power usage at the cost of small performance | |
3461 | overhead. | |
3462 | ||
3463 | The default value of this parameter is determined by | |
3464 | the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. | |
3465 | ||
3466 | x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of | |
3467 | default x2apic cluster mode on platforms | |
3468 | supporting x2apic. | |
3469 | ||
3470 | x86_mrst_timer= [X86-32,APBT] | |
3471 | Choose timer option for x86 Moorestown MID platform. | |
3472 | Two valid options are apbt timer only and lapic timer | |
3473 | plus one apbt timer for broadcast timer. | |
3474 | x86_mrst_timer=apbt_only | lapic_and_apbt | |
3475 | ||
3476 | xen_emul_unplug= [HW,X86,XEN] | |
3477 | Unplug Xen emulated devices | |
3478 | Format: [unplug0,][unplug1] | |
3479 | ide-disks -- unplug primary master IDE devices | |
3480 | aux-ide-disks -- unplug non-primary-master IDE devices | |
3481 | nics -- unplug network devices | |
3482 | all -- unplug all emulated devices (NICs and IDE disks) | |
3483 | unnecessary -- unplugging emulated devices is | |
3484 | unnecessary even if the host did not respond to | |
3485 | the unplug protocol | |
3486 | never -- do not unplug even if version check succeeds | |
3487 | ||
3488 | xirc2ps_cs= [NET,PCMCIA] | |
3489 | Format: | |
3490 | <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] | |
3491 | ||
3492 | ______________________________________________________________________ | |
3493 | ||
3494 | TODO: | |
3495 | ||
3496 | Add more DRM drivers. |