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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 | |
5 | implemented by the __setup(), core_param() and module_param() macros | |
6 | and sorted into English Dictionary order (defined as ignoring all | |
7 | punctuation and sorting digits before letters in a case insensitive | |
8 | manner), and with descriptions where known. | |
9 | ||
10 | The kernel parses parameters from the kernel command line up to "--"; | |
11 | if it doesn't recognize a parameter and it doesn't contain a '.', the | |
12 | parameter gets passed to init: parameters with '=' go into init's | |
13 | environment, others are passed as command line arguments to init. | |
14 | Everything after "--" is passed as an argument to init. | |
15 | ||
16 | Module parameters can be specified in two ways: via the kernel command | |
17 | line with a module name prefix, or via modprobe, e.g.: | |
18 | ||
19 | (kernel command line) usbcore.blinkenlights=1 | |
20 | (modprobe command line) modprobe usbcore blinkenlights=1 | |
21 | ||
22 | Parameters for modules which are built into the kernel need to be | |
23 | specified on the kernel command line. modprobe looks through the | |
24 | kernel command line (/proc/cmdline) and collects module parameters | |
25 | when it loads a module, so the kernel command line can be used for | |
26 | loadable modules too. | |
27 | ||
28 | Hyphens (dashes) and underscores are equivalent in parameter names, so | |
29 | log_buf_len=1M print-fatal-signals=1 | |
30 | can also be entered as | |
31 | log-buf-len=1M print_fatal_signals=1 | |
32 | ||
33 | Double-quotes can be used to protect spaces in values, e.g.: | |
34 | param="spaces in here" | |
35 | ||
36 | This document may not be entirely up to date and comprehensive. The command | |
37 | "modinfo -p ${modulename}" shows a current list of all parameters of a loadable | |
38 | module. Loadable modules, after being loaded into the running kernel, also | |
39 | reveal their parameters in /sys/module/${modulename}/parameters/. Some of these | |
40 | parameters may be changed at runtime by the command | |
41 | "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}". | |
42 | ||
43 | The parameters listed below are only valid if certain kernel build options were | |
44 | enabled and if respective hardware is present. The text in square brackets at | |
45 | the beginning of each description states the restrictions within which a | |
46 | parameter is applicable: | |
47 | ||
48 | ACPI ACPI support is enabled. | |
49 | AGP AGP (Accelerated Graphics Port) is enabled. | |
50 | ALSA ALSA sound support is enabled. | |
51 | APIC APIC support is enabled. | |
52 | APM Advanced Power Management support is enabled. | |
53 | ARM ARM architecture is enabled. | |
54 | AVR32 AVR32 architecture is enabled. | |
55 | AX25 Appropriate AX.25 support is enabled. | |
56 | BLACKFIN Blackfin architecture is enabled. | |
57 | CLK Common clock infrastructure is enabled. | |
58 | CMA Contiguous Memory Area support is enabled. | |
59 | DRM Direct Rendering Management support is enabled. | |
60 | DYNAMIC_DEBUG Build in debug messages and enable them at runtime | |
61 | EDD BIOS Enhanced Disk Drive Services (EDD) is enabled | |
62 | EFI EFI Partitioning (GPT) is enabled | |
63 | EIDE EIDE/ATAPI support is enabled. | |
64 | EVM Extended Verification Module | |
65 | FB The frame buffer device is enabled. | |
66 | FTRACE Function tracing enabled. | |
67 | GCOV GCOV profiling is enabled. | |
68 | HW Appropriate hardware is enabled. | |
69 | IA-64 IA-64 architecture is enabled. | |
70 | IMA Integrity measurement architecture is enabled. | |
71 | IOSCHED More than one I/O scheduler is enabled. | |
72 | IP_PNP IP DHCP, BOOTP, or RARP is enabled. | |
73 | IPV6 IPv6 support is enabled. | |
74 | ISAPNP ISA PnP code is enabled. | |
75 | ISDN Appropriate ISDN support is enabled. | |
76 | JOY Appropriate joystick support is enabled. | |
77 | KGDB Kernel debugger support is enabled. | |
78 | KVM Kernel Virtual Machine support is enabled. | |
79 | LIBATA Libata driver is enabled | |
80 | LP Printer support is enabled. | |
81 | LOOP Loopback device support is enabled. | |
82 | M68k M68k architecture is enabled. | |
83 | These options have more detailed description inside of | |
84 | Documentation/m68k/kernel-options.txt. | |
85 | MDA MDA console support is enabled. | |
86 | MIPS MIPS architecture is enabled. | |
87 | MOUSE Appropriate mouse support is enabled. | |
88 | MSI Message Signaled Interrupts (PCI). | |
89 | MTD MTD (Memory Technology Device) support is enabled. | |
90 | NET Appropriate network support is enabled. | |
91 | NUMA NUMA support is enabled. | |
92 | NFS Appropriate NFS support is enabled. | |
93 | OSS OSS sound support is enabled. | |
94 | PV_OPS A paravirtualized kernel is enabled. | |
95 | PARIDE The ParIDE (parallel port IDE) subsystem is enabled. | |
96 | PARISC The PA-RISC architecture is enabled. | |
97 | PCI PCI bus support is enabled. | |
98 | PCIE PCI Express support is enabled. | |
99 | PCMCIA The PCMCIA subsystem is enabled. | |
100 | PNP Plug & Play support is enabled. | |
101 | PPC PowerPC architecture is enabled. | |
102 | PPT Parallel port support is enabled. | |
103 | PS2 Appropriate PS/2 support is enabled. | |
104 | RAM RAM disk support is enabled. | |
105 | S390 S390 architecture is enabled. | |
106 | SCSI Appropriate SCSI support is enabled. | |
107 | A lot of drivers have their options described inside | |
108 | the Documentation/scsi/ sub-directory. | |
109 | SECURITY Different security models are enabled. | |
110 | SELINUX SELinux support is enabled. | |
111 | APPARMOR AppArmor support is enabled. | |
112 | SERIAL Serial support is enabled. | |
113 | SH SuperH architecture is enabled. | |
114 | SMP The kernel is an SMP kernel. | |
115 | SPARC Sparc architecture is enabled. | |
116 | SWSUSP Software suspend (hibernation) is enabled. | |
117 | SUSPEND System suspend states are enabled. | |
118 | TPM TPM drivers are enabled. | |
119 | TS Appropriate touchscreen support is enabled. | |
120 | UMS USB Mass Storage support is enabled. | |
121 | USB USB support is enabled. | |
122 | USBHID USB Human Interface Device support is enabled. | |
123 | V4L Video For Linux support is enabled. | |
124 | VMMIO Driver for memory mapped virtio devices is enabled. | |
125 | VGA The VGA console has been enabled. | |
126 | VT Virtual terminal support is enabled. | |
127 | WDT Watchdog support is enabled. | |
128 | XT IBM PC/XT MFM hard disk support is enabled. | |
129 | X86-32 X86-32, aka i386 architecture is enabled. | |
130 | X86-64 X86-64 architecture is enabled. | |
131 | More X86-64 boot options can be found in | |
132 | Documentation/x86/x86_64/boot-options.txt . | |
133 | X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64) | |
134 | XEN Xen support is enabled | |
135 | ||
136 | In addition, the following text indicates that the option: | |
137 | ||
138 | BUGS= Relates to possible processor bugs on the said processor. | |
139 | KNL Is a kernel start-up parameter. | |
140 | BOOT Is a boot loader parameter. | |
141 | ||
142 | Parameters denoted with BOOT are actually interpreted by the boot | |
143 | loader, and have no meaning to the kernel directly. | |
144 | Do not modify the syntax of boot loader parameters without extreme | |
145 | need or coordination with <Documentation/x86/boot.txt>. | |
146 | ||
147 | There are also arch-specific kernel-parameters not documented here. | |
148 | See for example <Documentation/x86/x86_64/boot-options.txt>. | |
149 | ||
150 | Note that ALL kernel parameters listed below are CASE SENSITIVE, and that | |
151 | a trailing = on the name of any parameter states that that parameter will | |
152 | be entered as an environment variable, whereas its absence indicates that | |
153 | it will appear as a kernel argument readable via /proc/cmdline by programs | |
154 | running once the system is up. | |
155 | ||
156 | The number of kernel parameters is not limited, but the length of the | |
157 | complete command line (parameters including spaces etc.) is limited to | |
158 | a fixed number of characters. This limit depends on the architecture | |
159 | and is between 256 and 4096 characters. It is defined in the file | |
160 | ./include/asm/setup.h as COMMAND_LINE_SIZE. | |
161 | ||
162 | Finally, the [KMG] suffix is commonly described after a number of kernel | |
163 | parameter values. These 'K', 'M', and 'G' letters represent the _binary_ | |
164 | multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30 | |
165 | bytes respectively. Such letter suffixes can also be entirely omitted. | |
166 | ||
167 | ||
168 | acpi= [HW,ACPI,X86,ARM64] | |
169 | Advanced Configuration and Power Interface | |
170 | Format: { force | off | strict | noirq | rsdt | | |
171 | copy_dsdt } | |
172 | force -- enable ACPI if default was off | |
173 | off -- disable ACPI if default was on | |
174 | noirq -- do not use ACPI for IRQ routing | |
175 | strict -- Be less tolerant of platforms that are not | |
176 | strictly ACPI specification compliant. | |
177 | rsdt -- prefer RSDT over (default) XSDT | |
178 | copy_dsdt -- copy DSDT to memory | |
179 | For ARM64, ONLY "acpi=off" or "acpi=force" are available | |
180 | ||
181 | See also Documentation/power/runtime_pm.txt, pci=noacpi | |
182 | ||
183 | acpi_apic_instance= [ACPI, IOAPIC] | |
184 | Format: <int> | |
185 | 2: use 2nd APIC table, if available | |
186 | 1,0: use 1st APIC table | |
187 | default: 0 | |
188 | ||
189 | acpi_backlight= [HW,ACPI] | |
190 | acpi_backlight=vendor | |
191 | acpi_backlight=video | |
192 | If set to vendor, prefer vendor specific driver | |
193 | (e.g. thinkpad_acpi, sony_acpi, etc.) instead | |
194 | of the ACPI video.ko driver. | |
195 | ||
196 | acpica_no_return_repair [HW, ACPI] | |
197 | Disable AML predefined validation mechanism | |
198 | This mechanism can repair the evaluation result to make | |
199 | the return objects more ACPI specification compliant. | |
200 | This option is useful for developers to identify the | |
201 | root cause of an AML interpreter issue when the issue | |
202 | has something to do with the repair mechanism. | |
203 | ||
204 | acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] | |
205 | acpi.debug_level= [HW,ACPI,ACPI_DEBUG] | |
206 | Format: <int> | |
207 | CONFIG_ACPI_DEBUG must be enabled to produce any ACPI | |
208 | debug output. Bits in debug_layer correspond to a | |
209 | _COMPONENT in an ACPI source file, e.g., | |
210 | #define _COMPONENT ACPI_PCI_COMPONENT | |
211 | Bits in debug_level correspond to a level in | |
212 | ACPI_DEBUG_PRINT statements, e.g., | |
213 | ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... | |
214 | The debug_level mask defaults to "info". See | |
215 | Documentation/acpi/debug.txt for more information about | |
216 | debug layers and levels. | |
217 | ||
218 | Enable processor driver info messages: | |
219 | acpi.debug_layer=0x20000000 | |
220 | Enable PCI/PCI interrupt routing info messages: | |
221 | acpi.debug_layer=0x400000 | |
222 | Enable AML "Debug" output, i.e., stores to the Debug | |
223 | object while interpreting AML: | |
224 | acpi.debug_layer=0xffffffff acpi.debug_level=0x2 | |
225 | Enable all messages related to ACPI hardware: | |
226 | acpi.debug_layer=0x2 acpi.debug_level=0xffffffff | |
227 | ||
228 | Some values produce so much output that the system is | |
229 | unusable. The "log_buf_len" parameter may be useful | |
230 | if you need to capture more output. | |
231 | ||
232 | acpi_enforce_resources= [ACPI] | |
233 | { strict | lax | no } | |
234 | Check for resource conflicts between native drivers | |
235 | and ACPI OperationRegions (SystemIO and SystemMemory | |
236 | only). IO ports and memory declared in ACPI might be | |
237 | used by the ACPI subsystem in arbitrary AML code and | |
238 | can interfere with legacy drivers. | |
239 | strict (default): access to resources claimed by ACPI | |
240 | is denied; legacy drivers trying to access reserved | |
241 | resources will fail to bind to device using them. | |
242 | lax: access to resources claimed by ACPI is allowed; | |
243 | legacy drivers trying to access reserved resources | |
244 | will bind successfully but a warning message is logged. | |
245 | no: ACPI OperationRegions are not marked as reserved, | |
246 | no further checks are performed. | |
247 | ||
248 | acpi_force_table_verification [HW,ACPI] | |
249 | Enable table checksum verification during early stage. | |
250 | By default, this is disabled due to x86 early mapping | |
251 | size limitation. | |
252 | ||
253 | acpi_irq_balance [HW,ACPI] | |
254 | ACPI will balance active IRQs | |
255 | default in APIC mode | |
256 | ||
257 | acpi_irq_nobalance [HW,ACPI] | |
258 | ACPI will not move active IRQs (default) | |
259 | default in PIC mode | |
260 | ||
261 | acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA | |
262 | Format: <irq>,<irq>... | |
263 | ||
264 | acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for | |
265 | use by PCI | |
266 | Format: <irq>,<irq>... | |
267 | ||
268 | acpi_no_auto_serialize [HW,ACPI] | |
269 | Disable auto-serialization of AML methods | |
270 | AML control methods that contain the opcodes to create | |
271 | named objects will be marked as "Serialized" by the | |
272 | auto-serialization feature. | |
273 | This feature is enabled by default. | |
274 | This option allows to turn off the feature. | |
275 | ||
276 | acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump | |
277 | kernels. | |
278 | ||
279 | acpi_no_static_ssdt [HW,ACPI] | |
280 | Disable installation of static SSDTs at early boot time | |
281 | By default, SSDTs contained in the RSDT/XSDT will be | |
282 | installed automatically and they will appear under | |
283 | /sys/firmware/acpi/tables. | |
284 | This option turns off this feature. | |
285 | Note that specifying this option does not affect | |
286 | dynamic table installation which will install SSDT | |
287 | tables to /sys/firmware/acpi/tables/dynamic. | |
288 | ||
289 | acpi_rsdp= [ACPI,EFI,KEXEC] | |
290 | Pass the RSDP address to the kernel, mostly used | |
291 | on machines running EFI runtime service to boot the | |
292 | second kernel for kdump. | |
293 | ||
294 | acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS | |
295 | Format: To spoof as Windows 98: ="Microsoft Windows" | |
296 | ||
297 | acpi_rev_override [ACPI] Override the _REV object to return 5 (instead | |
298 | of 2 which is mandated by ACPI 6) as the supported ACPI | |
299 | specification revision (when using this switch, it may | |
300 | be necessary to carry out a cold reboot _twice_ in a | |
301 | row to make it take effect on the platform firmware). | |
302 | ||
303 | acpi_osi= [HW,ACPI] Modify list of supported OS interface strings | |
304 | acpi_osi="string1" # add string1 | |
305 | acpi_osi="!string2" # remove string2 | |
306 | acpi_osi=!* # remove all strings | |
307 | acpi_osi=! # disable all built-in OS vendor | |
308 | strings | |
309 | acpi_osi= # disable all strings | |
310 | ||
311 | 'acpi_osi=!' can be used in combination with single or | |
312 | multiple 'acpi_osi="string1"' to support specific OS | |
313 | vendor string(s). Note that such command can only | |
314 | affect the default state of the OS vendor strings, thus | |
315 | it cannot affect the default state of the feature group | |
316 | strings and the current state of the OS vendor strings, | |
317 | specifying it multiple times through kernel command line | |
318 | is meaningless. This command is useful when one do not | |
319 | care about the state of the feature group strings which | |
320 | should be controlled by the OSPM. | |
321 | Examples: | |
322 | 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent | |
323 | to 'acpi_osi="Windows 2000" acpi_osi=!', they all | |
324 | can make '_OSI("Windows 2000")' TRUE. | |
325 | ||
326 | 'acpi_osi=' cannot be used in combination with other | |
327 | 'acpi_osi=' command lines, the _OSI method will not | |
328 | exist in the ACPI namespace. NOTE that such command can | |
329 | only affect the _OSI support state, thus specifying it | |
330 | multiple times through kernel command line is also | |
331 | meaningless. | |
332 | Examples: | |
333 | 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' | |
334 | FALSE. | |
335 | ||
336 | 'acpi_osi=!*' can be used in combination with single or | |
337 | multiple 'acpi_osi="string1"' to support specific | |
338 | string(s). Note that such command can affect the | |
339 | current state of both the OS vendor strings and the | |
340 | feature group strings, thus specifying it multiple times | |
341 | through kernel command line is meaningful. But it may | |
342 | still not able to affect the final state of a string if | |
343 | there are quirks related to this string. This command | |
344 | is useful when one want to control the state of the | |
345 | feature group strings to debug BIOS issues related to | |
346 | the OSPM features. | |
347 | Examples: | |
348 | 1. 'acpi_osi="Module Device" acpi_osi=!*' can make | |
349 | '_OSI("Module Device")' FALSE. | |
350 | 2. 'acpi_osi=!* acpi_osi="Module Device"' can make | |
351 | '_OSI("Module Device")' TRUE. | |
352 | 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is | |
353 | equivalent to | |
354 | 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' | |
355 | and | |
356 | 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', | |
357 | they all will make '_OSI("Windows 2000")' TRUE. | |
358 | ||
359 | acpi_pm_good [X86] | |
360 | Override the pmtimer bug detection: force the kernel | |
361 | to assume that this machine's pmtimer latches its value | |
362 | and always returns good values. | |
363 | ||
364 | acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode | |
365 | Format: { level | edge | high | low } | |
366 | ||
367 | acpi_skip_timer_override [HW,ACPI] | |
368 | Recognize and ignore IRQ0/pin2 Interrupt Override. | |
369 | For broken nForce2 BIOS resulting in XT-PIC timer. | |
370 | ||
371 | acpi_sleep= [HW,ACPI] Sleep options | |
372 | Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, | |
373 | old_ordering, nonvs, sci_force_enable } | |
374 | See Documentation/power/video.txt for information on | |
375 | s3_bios and s3_mode. | |
376 | s3_beep is for debugging; it makes the PC's speaker beep | |
377 | as soon as the kernel's real-mode entry point is called. | |
378 | s4_nohwsig prevents ACPI hardware signature from being | |
379 | used during resume from hibernation. | |
380 | old_ordering causes the ACPI 1.0 ordering of the _PTS | |
381 | control method, with respect to putting devices into | |
382 | low power states, to be enforced (the ACPI 2.0 ordering | |
383 | of _PTS is used by default). | |
384 | nonvs prevents the kernel from saving/restoring the | |
385 | ACPI NVS memory during suspend/hibernation and resume. | |
386 | sci_force_enable causes the kernel to set SCI_EN directly | |
387 | on resume from S1/S3 (which is against the ACPI spec, | |
388 | but some broken systems don't work without it). | |
389 | ||
390 | acpi_use_timer_override [HW,ACPI] | |
391 | Use timer override. For some broken Nvidia NF5 boards | |
392 | that require a timer override, but don't have HPET | |
393 | ||
394 | add_efi_memmap [EFI; X86] Include EFI memory map in | |
395 | kernel's map of available physical RAM. | |
396 | ||
397 | agp= [AGP] | |
398 | { off | try_unsupported } | |
399 | off: disable AGP support | |
400 | try_unsupported: try to drive unsupported chipsets | |
401 | (may crash computer or cause data corruption) | |
402 | ||
403 | ALSA [HW,ALSA] | |
404 | See Documentation/sound/alsa/alsa-parameters.txt | |
405 | ||
406 | alignment= [KNL,ARM] | |
407 | Allow the default userspace alignment fault handler | |
408 | behaviour to be specified. Bit 0 enables warnings, | |
409 | bit 1 enables fixups, and bit 2 sends a segfault. | |
410 | ||
411 | align_va_addr= [X86-64] | |
412 | Align virtual addresses by clearing slice [14:12] when | |
413 | allocating a VMA at process creation time. This option | |
414 | gives you up to 3% performance improvement on AMD F15h | |
415 | machines (where it is enabled by default) for a | |
416 | CPU-intensive style benchmark, and it can vary highly in | |
417 | a microbenchmark depending on workload and compiler. | |
418 | ||
419 | 32: only for 32-bit processes | |
420 | 64: only for 64-bit processes | |
421 | on: enable for both 32- and 64-bit processes | |
422 | off: disable for both 32- and 64-bit processes | |
423 | ||
424 | alloc_snapshot [FTRACE] | |
425 | Allocate the ftrace snapshot buffer on boot up when the | |
426 | main buffer is allocated. This is handy if debugging | |
427 | and you need to use tracing_snapshot() on boot up, and | |
428 | do not want to use tracing_snapshot_alloc() as it needs | |
429 | to be done where GFP_KERNEL allocations are allowed. | |
430 | ||
431 | amd_iommu= [HW,X86-64] | |
432 | Pass parameters to the AMD IOMMU driver in the system. | |
433 | Possible values are: | |
434 | fullflush - enable flushing of IO/TLB entries when | |
435 | they are unmapped. Otherwise they are | |
436 | flushed before they will be reused, which | |
437 | is a lot of faster | |
438 | off - do not initialize any AMD IOMMU found in | |
439 | the system | |
440 | force_isolation - Force device isolation for all | |
441 | devices. The IOMMU driver is not | |
442 | allowed anymore to lift isolation | |
443 | requirements as needed. This option | |
444 | does not override iommu=pt | |
445 | ||
446 | amd_iommu_dump= [HW,X86-64] | |
447 | Enable AMD IOMMU driver option to dump the ACPI table | |
448 | for AMD IOMMU. With this option enabled, AMD IOMMU | |
449 | driver will print ACPI tables for AMD IOMMU during | |
450 | IOMMU initialization. | |
451 | ||
452 | amijoy.map= [HW,JOY] Amiga joystick support | |
453 | Map of devices attached to JOY0DAT and JOY1DAT | |
454 | Format: <a>,<b> | |
455 | See also Documentation/input/joystick.txt | |
456 | ||
457 | analog.map= [HW,JOY] Analog joystick and gamepad support | |
458 | Specifies type or capabilities of an analog joystick | |
459 | connected to one of 16 gameports | |
460 | Format: <type1>,<type2>,..<type16> | |
461 | ||
462 | apc= [HW,SPARC] | |
463 | Power management functions (SPARCstation-4/5 + deriv.) | |
464 | Format: noidle | |
465 | Disable APC CPU standby support. SPARCstation-Fox does | |
466 | not play well with APC CPU idle - disable it if you have | |
467 | APC and your system crashes randomly. | |
468 | ||
469 | apic= [APIC,X86-32] Advanced Programmable Interrupt Controller | |
470 | Change the output verbosity whilst booting | |
471 | Format: { quiet (default) | verbose | debug } | |
472 | Change the amount of debugging information output | |
473 | when initialising the APIC and IO-APIC components. | |
474 | ||
475 | autoconf= [IPV6] | |
476 | See Documentation/networking/ipv6.txt. | |
477 | ||
478 | show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller | |
479 | Limit apic dumping. The parameter defines the maximal | |
480 | number of local apics being dumped. Also it is possible | |
481 | to set it to "all" by meaning -- no limit here. | |
482 | Format: { 1 (default) | 2 | ... | all }. | |
483 | The parameter valid if only apic=debug or | |
484 | apic=verbose is specified. | |
485 | Example: apic=debug show_lapic=all | |
486 | ||
487 | apm= [APM] Advanced Power Management | |
488 | See header of arch/x86/kernel/apm_32.c. | |
489 | ||
490 | arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards | |
491 | Format: <io>,<irq>,<nodeID> | |
492 | ||
493 | ataflop= [HW,M68k] | |
494 | ||
495 | atarimouse= [HW,MOUSE] Atari Mouse | |
496 | ||
497 | atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, | |
498 | EzKey and similar keyboards | |
499 | ||
500 | atkbd.reset= [HW] Reset keyboard during initialization | |
501 | ||
502 | atkbd.set= [HW] Select keyboard code set | |
503 | Format: <int> (2 = AT (default), 3 = PS/2) | |
504 | ||
505 | atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar | |
506 | keyboards | |
507 | ||
508 | atkbd.softraw= [HW] Choose between synthetic and real raw mode | |
509 | Format: <bool> (0 = real, 1 = synthetic (default)) | |
510 | ||
511 | atkbd.softrepeat= [HW] | |
512 | Use software keyboard repeat | |
513 | ||
514 | audit= [KNL] Enable the audit sub-system | |
515 | Format: { "0" | "1" } (0 = disabled, 1 = enabled) | |
516 | 0 - kernel audit is disabled and can not be enabled | |
517 | until the next reboot | |
518 | unset - kernel audit is initialized but disabled and | |
519 | will be fully enabled by the userspace auditd. | |
520 | 1 - kernel audit is initialized and partially enabled, | |
521 | storing at most audit_backlog_limit messages in | |
522 | RAM until it is fully enabled by the userspace | |
523 | auditd. | |
524 | Default: unset | |
525 | ||
526 | audit_backlog_limit= [KNL] Set the audit queue size limit. | |
527 | Format: <int> (must be >=0) | |
528 | Default: 64 | |
529 | ||
530 | baycom_epp= [HW,AX25] | |
531 | Format: <io>,<mode> | |
532 | ||
533 | baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem | |
534 | Format: <io>,<mode> | |
535 | See header of drivers/net/hamradio/baycom_par.c. | |
536 | ||
537 | baycom_ser_fdx= [HW,AX25] | |
538 | BayCom Serial Port AX.25 Modem (Full Duplex Mode) | |
539 | Format: <io>,<irq>,<mode>[,<baud>] | |
540 | See header of drivers/net/hamradio/baycom_ser_fdx.c. | |
541 | ||
542 | baycom_ser_hdx= [HW,AX25] | |
543 | BayCom Serial Port AX.25 Modem (Half Duplex Mode) | |
544 | Format: <io>,<irq>,<mode> | |
545 | See header of drivers/net/hamradio/baycom_ser_hdx.c. | |
546 | ||
547 | blkdevparts= Manual partition parsing of block device(s) for | |
548 | embedded devices based on command line input. | |
549 | See Documentation/block/cmdline-partition.txt | |
550 | ||
551 | boot_delay= Milliseconds to delay each printk during boot. | |
552 | Values larger than 10 seconds (10000) are changed to | |
553 | no delay (0). | |
554 | Format: integer | |
555 | ||
556 | bootmem_debug [KNL] Enable bootmem allocator debug messages. | |
557 | ||
558 | bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) | |
559 | bttv.radio= Most important insmod options are available as | |
560 | kernel args too. | |
561 | bttv.pll= See Documentation/video4linux/bttv/Insmod-options | |
562 | bttv.tuner= | |
563 | ||
564 | bulk_remove=off [PPC] This parameter disables the use of the pSeries | |
565 | firmware feature for flushing multiple hpte entries | |
566 | at a time. | |
567 | ||
568 | c101= [NET] Moxa C101 synchronous serial card | |
569 | ||
570 | cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. | |
571 | Sometimes CPU hardware bugs make them report the cache | |
572 | size incorrectly. The kernel will attempt work arounds | |
573 | to fix known problems, but for some CPUs it is not | |
574 | possible to determine what the correct size should be. | |
575 | This option provides an override for these situations. | |
576 | ||
577 | ca_keys= [KEYS] This parameter identifies a specific key(s) on | |
578 | the system trusted keyring to be used for certificate | |
579 | trust validation. | |
580 | format: { id:<keyid> | builtin } | |
581 | ||
582 | cca= [MIPS] Override the kernel pages' cache coherency | |
583 | algorithm. Accepted values range from 0 to 7 | |
584 | inclusive. See arch/mips/include/asm/pgtable-bits.h | |
585 | for platform specific values (SB1, Loongson3 and | |
586 | others). | |
587 | ||
588 | ccw_timeout_log [S390] | |
589 | See Documentation/s390/CommonIO for details. | |
590 | ||
591 | cgroup_disable= [KNL] Disable a particular controller | |
592 | Format: {name of the controller(s) to disable} | |
593 | The effects of cgroup_disable=foo are: | |
594 | - foo isn't auto-mounted if you mount all cgroups in | |
595 | a single hierarchy | |
596 | - foo isn't visible as an individually mountable | |
597 | subsystem | |
598 | {Currently only "memory" controller deal with this and | |
599 | cut the overhead, others just disable the usage. So | |
600 | only cgroup_disable=memory is actually worthy} | |
601 | ||
602 | checkreqprot [SELINUX] Set initial checkreqprot flag value. | |
603 | Format: { "0" | "1" } | |
604 | See security/selinux/Kconfig help text. | |
605 | 0 -- check protection applied by kernel (includes | |
606 | any implied execute protection). | |
607 | 1 -- check protection requested by application. | |
608 | Default value is set via a kernel config option. | |
609 | Value can be changed at runtime via | |
610 | /selinux/checkreqprot. | |
611 | ||
612 | cio_ignore= [S390] | |
613 | See Documentation/s390/CommonIO for details. | |
614 | clk_ignore_unused | |
615 | [CLK] | |
616 | Prevents the clock framework from automatically gating | |
617 | clocks that have not been explicitly enabled by a Linux | |
618 | device driver but are enabled in hardware at reset or | |
619 | by the bootloader/firmware. Note that this does not | |
620 | force such clocks to be always-on nor does it reserve | |
621 | those clocks in any way. This parameter is useful for | |
622 | debug and development, but should not be needed on a | |
623 | platform with proper driver support. For more | |
624 | information, see Documentation/clk.txt. | |
625 | ||
626 | clock= [BUGS=X86-32, HW] gettimeofday clocksource override. | |
627 | [Deprecated] | |
628 | Forces specified clocksource (if available) to be used | |
629 | when calculating gettimeofday(). If specified | |
630 | clocksource is not available, it defaults to PIT. | |
631 | Format: { pit | tsc | cyclone | pmtmr } | |
632 | ||
633 | clocksource= Override the default clocksource | |
634 | Format: <string> | |
635 | Override the default clocksource and use the clocksource | |
636 | with the name specified. | |
637 | Some clocksource names to choose from, depending on | |
638 | the platform: | |
639 | [all] jiffies (this is the base, fallback clocksource) | |
640 | [ACPI] acpi_pm | |
641 | [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, | |
642 | pxa_timer,timer3,32k_counter,timer0_1 | |
643 | [AVR32] avr32 | |
644 | [X86-32] pit,hpet,tsc; | |
645 | scx200_hrt on Geode; cyclone on IBM x440 | |
646 | [MIPS] MIPS | |
647 | [PARISC] cr16 | |
648 | [S390] tod | |
649 | [SH] SuperH | |
650 | [SPARC64] tick | |
651 | [X86-64] hpet,tsc | |
652 | ||
653 | clearcpuid=BITNUM [X86] | |
654 | Disable CPUID feature X for the kernel. See | |
655 | arch/x86/include/asm/cpufeature.h for the valid bit | |
656 | numbers. Note the Linux specific bits are not necessarily | |
657 | stable over kernel options, but the vendor specific | |
658 | ones should be. | |
659 | Also note that user programs calling CPUID directly | |
660 | or using the feature without checking anything | |
661 | will still see it. This just prevents it from | |
662 | being used by the kernel or shown in /proc/cpuinfo. | |
663 | Also note the kernel might malfunction if you disable | |
664 | some critical bits. | |
665 | ||
666 | cma=nn[MG]@[start[MG][-end[MG]]] | |
667 | [ARM,X86,KNL] | |
668 | Sets the size of kernel global memory area for | |
669 | contiguous memory allocations and optionally the | |
670 | placement constraint by the physical address range of | |
671 | memory allocations. A value of 0 disables CMA | |
672 | altogether. For more information, see | |
673 | include/linux/dma-contiguous.h | |
674 | ||
675 | cmo_free_hint= [PPC] Format: { yes | no } | |
676 | Specify whether pages are marked as being inactive | |
677 | when they are freed. This is used in CMO environments | |
678 | to determine OS memory pressure for page stealing by | |
679 | a hypervisor. | |
680 | Default: yes | |
681 | ||
682 | coherent_pool=nn[KMG] [ARM,KNL] | |
683 | Sets the size of memory pool for coherent, atomic dma | |
684 | allocations, by default set to 256K. | |
685 | ||
686 | code_bytes [X86] How many bytes of object code to print | |
687 | in an oops report. | |
688 | Range: 0 - 8192 | |
689 | Default: 64 | |
690 | ||
691 | com20020= [HW,NET] ARCnet - COM20020 chipset | |
692 | Format: | |
693 | <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] | |
694 | ||
695 | com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) | |
696 | Format: <io>[,<irq>] | |
697 | ||
698 | com90xx= [HW,NET] | |
699 | ARCnet - COM90xx chipset (memory-mapped buffers) | |
700 | Format: <io>[,<irq>[,<memstart>]] | |
701 | ||
702 | condev= [HW,S390] console device | |
703 | conmode= | |
704 | ||
705 | console= [KNL] Output console device and options. | |
706 | ||
707 | tty<n> Use the virtual console device <n>. | |
708 | ||
709 | ttyS<n>[,options] | |
710 | ttyUSB0[,options] | |
711 | Use the specified serial port. The options are of | |
712 | the form "bbbbpnf", where "bbbb" is the baud rate, | |
713 | "p" is parity ("n", "o", or "e"), "n" is number of | |
714 | bits, and "f" is flow control ("r" for RTS or | |
715 | omit it). Default is "9600n8". | |
716 | ||
717 | See Documentation/serial-console.txt for more | |
718 | information. See | |
719 | Documentation/networking/netconsole.txt for an | |
720 | alternative. | |
721 | ||
722 | uart[8250],io,<addr>[,options] | |
723 | uart[8250],mmio,<addr>[,options] | |
724 | uart[8250],mmio32,<addr>[,options] | |
725 | uart[8250],0x<addr>[,options] | |
726 | Start an early, polled-mode console on the 8250/16550 | |
727 | UART at the specified I/O port or MMIO address, | |
728 | switching to the matching ttyS device later. | |
729 | MMIO inter-register address stride is either 8-bit | |
730 | (mmio) or 32-bit (mmio32). | |
731 | If none of [io|mmio|mmio32], <addr> is assumed to be | |
732 | equivalent to 'mmio'. 'options' are specified in the | |
733 | same format described for ttyS above; if unspecified, | |
734 | the h/w is not re-initialized. | |
735 | ||
736 | hvc<n> Use the hypervisor console device <n>. This is for | |
737 | both Xen and PowerPC hypervisors. | |
738 | ||
739 | If the device connected to the port is not a TTY but a braille | |
740 | device, prepend "brl," before the device type, for instance | |
741 | console=brl,ttyS0 | |
742 | For now, only VisioBraille is supported. | |
743 | ||
744 | consoleblank= [KNL] The console blank (screen saver) timeout in | |
745 | seconds. Defaults to 10*60 = 10mins. A value of 0 | |
746 | disables the blank timer. | |
747 | ||
748 | coredump_filter= | |
749 | [KNL] Change the default value for | |
750 | /proc/<pid>/coredump_filter. | |
751 | See also Documentation/filesystems/proc.txt. | |
752 | ||
753 | cpuidle.off=1 [CPU_IDLE] | |
754 | disable the cpuidle sub-system | |
755 | ||
756 | cpu_init_udelay=N | |
757 | [X86] Delay for N microsec between assert and de-assert | |
758 | of APIC INIT to start processors. This delay occurs | |
759 | on every CPU online, such as boot, and resume from suspend. | |
760 | Default: 10000 | |
761 | ||
762 | cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver | |
763 | Format: | |
764 | <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] | |
765 | ||
766 | crashkernel=size[KMG][@offset[KMG]] | |
767 | [KNL] Using kexec, Linux can switch to a 'crash kernel' | |
768 | upon panic. This parameter reserves the physical | |
769 | memory region [offset, offset + size] for that kernel | |
770 | image. If '@offset' is omitted, then a suitable offset | |
771 | is selected automatically. Check | |
772 | Documentation/kdump/kdump.txt for further details. | |
773 | ||
774 | crashkernel=range1:size1[,range2:size2,...][@offset] | |
775 | [KNL] Same as above, but depends on the memory | |
776 | in the running system. The syntax of range is | |
777 | start-[end] where start and end are both | |
778 | a memory unit (amount[KMG]). See also | |
779 | Documentation/kdump/kdump.txt for an example. | |
780 | ||
781 | crashkernel=size[KMG],high | |
782 | [KNL, x86_64] range could be above 4G. Allow kernel | |
783 | to allocate physical memory region from top, so could | |
784 | be above 4G if system have more than 4G ram installed. | |
785 | Otherwise memory region will be allocated below 4G, if | |
786 | available. | |
787 | It will be ignored if crashkernel=X is specified. | |
788 | crashkernel=size[KMG],low | |
789 | [KNL, x86_64] range under 4G. When crashkernel=X,high | |
790 | is passed, kernel could allocate physical memory region | |
791 | above 4G, that cause second kernel crash on system | |
792 | that require some amount of low memory, e.g. swiotlb | |
793 | requires at least 64M+32K low memory, also enough extra | |
794 | low memory is needed to make sure DMA buffers for 32-bit | |
795 | devices won't run out. Kernel would try to allocate at | |
796 | at least 256M below 4G automatically. | |
797 | This one let user to specify own low range under 4G | |
798 | for second kernel instead. | |
799 | 0: to disable low allocation. | |
800 | It will be ignored when crashkernel=X,high is not used | |
801 | or memory reserved is below 4G. | |
802 | ||
803 | cs89x0_dma= [HW,NET] | |
804 | Format: <dma> | |
805 | ||
806 | cs89x0_media= [HW,NET] | |
807 | Format: { rj45 | aui | bnc } | |
808 | ||
809 | dasd= [HW,NET] | |
810 | See header of drivers/s390/block/dasd_devmap.c. | |
811 | ||
812 | db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port | |
813 | (one device per port) | |
814 | Format: <port#>,<type> | |
815 | See also Documentation/input/joystick-parport.txt | |
816 | ||
817 | ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot | |
818 | time. See Documentation/dynamic-debug-howto.txt for | |
819 | details. Deprecated, see dyndbg. | |
820 | ||
821 | debug [KNL] Enable kernel debugging (events log level). | |
822 | ||
823 | debug_locks_verbose= | |
824 | [KNL] verbose self-tests | |
825 | Format=<0|1> | |
826 | Print debugging info while doing the locking API | |
827 | self-tests. | |
828 | We default to 0 (no extra messages), setting it to | |
829 | 1 will print _a lot_ more information - normally | |
830 | only useful to kernel developers. | |
831 | ||
832 | debug_objects [KNL] Enable object debugging | |
833 | ||
834 | no_debug_objects | |
835 | [KNL] Disable object debugging | |
836 | ||
837 | debug_guardpage_minorder= | |
838 | [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this | |
839 | parameter allows control of the order of pages that will | |
840 | be intentionally kept free (and hence protected) by the | |
841 | buddy allocator. Bigger value increase the probability | |
842 | of catching random memory corruption, but reduce the | |
843 | amount of memory for normal system use. The maximum | |
844 | possible value is MAX_ORDER/2. Setting this parameter | |
845 | to 1 or 2 should be enough to identify most random | |
846 | memory corruption problems caused by bugs in kernel or | |
847 | driver code when a CPU writes to (or reads from) a | |
848 | random memory location. Note that there exists a class | |
849 | of memory corruptions problems caused by buggy H/W or | |
850 | F/W or by drivers badly programing DMA (basically when | |
851 | memory is written at bus level and the CPU MMU is | |
852 | bypassed) which are not detectable by | |
853 | CONFIG_DEBUG_PAGEALLOC, hence this option will not help | |
854 | tracking down these problems. | |
855 | ||
856 | debug_pagealloc= | |
857 | [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this | |
858 | parameter enables the feature at boot time. In | |
859 | default, it is disabled. We can avoid allocating huge | |
860 | chunk of memory for debug pagealloc if we don't enable | |
861 | it at boot time and the system will work mostly same | |
862 | with the kernel built without CONFIG_DEBUG_PAGEALLOC. | |
863 | on: enable the feature | |
864 | ||
865 | debugpat [X86] Enable PAT debugging | |
866 | ||
867 | decnet.addr= [HW,NET] | |
868 | Format: <area>[,<node>] | |
869 | See also Documentation/networking/decnet.txt. | |
870 | ||
871 | default_hugepagesz= | |
872 | [same as hugepagesz=] The size of the default | |
873 | HugeTLB page size. This is the size represented by | |
874 | the legacy /proc/ hugepages APIs, used for SHM, and | |
875 | default size when mounting hugetlbfs filesystems. | |
876 | Defaults to the default architecture's huge page size | |
877 | if not specified. | |
878 | ||
879 | dhash_entries= [KNL] | |
880 | Set number of hash buckets for dentry cache. | |
881 | ||
882 | disable= [IPV6] | |
883 | See Documentation/networking/ipv6.txt. | |
884 | ||
885 | disable_cpu_apicid= [X86,APIC,SMP] | |
886 | Format: <int> | |
887 | The number of initial APIC ID for the | |
888 | corresponding CPU to be disabled at boot, | |
889 | mostly used for the kdump 2nd kernel to | |
890 | disable BSP to wake up multiple CPUs without | |
891 | causing system reset or hang due to sending | |
892 | INIT from AP to BSP. | |
893 | ||
894 | disable_ddw [PPC/PSERIES] | |
895 | Disable Dynamic DMA Window support. Use this if | |
896 | to workaround buggy firmware. | |
897 | ||
898 | disable_ipv6= [IPV6] | |
899 | See Documentation/networking/ipv6.txt. | |
900 | ||
901 | disable_mtrr_cleanup [X86] | |
902 | The kernel tries to adjust MTRR layout from continuous | |
903 | to discrete, to make X server driver able to add WB | |
904 | entry later. This parameter disables that. | |
905 | ||
906 | disable_mtrr_trim [X86, Intel and AMD only] | |
907 | By default the kernel will trim any uncacheable | |
908 | memory out of your available memory pool based on | |
909 | MTRR settings. This parameter disables that behavior, | |
910 | possibly causing your machine to run very slowly. | |
911 | ||
912 | disable_timer_pin_1 [X86] | |
913 | Disable PIN 1 of APIC timer | |
914 | Can be useful to work around chipset bugs. | |
915 | ||
916 | dis_ucode_ldr [X86] Disable the microcode loader. | |
917 | ||
918 | dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, | |
919 | this option disables the debugging code at boot. | |
920 | ||
921 | dma_debug_entries=<number> | |
922 | This option allows to tune the number of preallocated | |
923 | entries for DMA-API debugging code. One entry is | |
924 | required per DMA-API allocation. Use this if the | |
925 | DMA-API debugging code disables itself because the | |
926 | architectural default is too low. | |
927 | ||
928 | dma_debug_driver=<driver_name> | |
929 | With this option the DMA-API debugging driver | |
930 | filter feature can be enabled at boot time. Just | |
931 | pass the driver to filter for as the parameter. | |
932 | The filter can be disabled or changed to another | |
933 | driver later using sysfs. | |
934 | ||
935 | drm_kms_helper.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] | |
936 | Broken monitors, graphic adapters, KVMs and EDIDless | |
937 | panels may send no or incorrect EDID data sets. | |
938 | This parameter allows to specify an EDID data sets | |
939 | in the /lib/firmware directory that are used instead. | |
940 | Generic built-in EDID data sets are used, if one of | |
941 | edid/1024x768.bin, edid/1280x1024.bin, | |
942 | edid/1680x1050.bin, or edid/1920x1080.bin is given | |
943 | and no file with the same name exists. Details and | |
944 | instructions how to build your own EDID data are | |
945 | available in Documentation/EDID/HOWTO.txt. An EDID | |
946 | data set will only be used for a particular connector, | |
947 | if its name and a colon are prepended to the EDID | |
948 | name. Each connector may use a unique EDID data | |
949 | set by separating the files with a comma. An EDID | |
950 | data set with no connector name will be used for | |
951 | any connectors not explicitly specified. | |
952 | ||
953 | dscc4.setup= [NET] | |
954 | ||
955 | dyndbg[="val"] [KNL,DYNAMIC_DEBUG] | |
956 | module.dyndbg[="val"] | |
957 | Enable debug messages at boot time. See | |
958 | Documentation/dynamic-debug-howto.txt for details. | |
959 | ||
960 | nompx [X86] Disables Intel Memory Protection Extensions. | |
961 | See Documentation/x86/intel_mpx.txt for more | |
962 | information about the feature. | |
963 | ||
964 | eagerfpu= [X86] | |
965 | on enable eager fpu restore | |
966 | off disable eager fpu restore | |
967 | auto selects the default scheme, which automatically | |
968 | enables eagerfpu restore for xsaveopt. | |
969 | ||
970 | module.async_probe [KNL] | |
971 | Enable asynchronous probe on this module. | |
972 | ||
973 | early_ioremap_debug [KNL] | |
974 | Enable debug messages in early_ioremap support. This | |
975 | is useful for tracking down temporary early mappings | |
976 | which are not unmapped. | |
977 | ||
978 | earlycon= [KNL] Output early console device and options. | |
979 | ||
980 | When used with no options, the early console is | |
981 | determined by the stdout-path property in device | |
982 | tree's chosen node. | |
983 | ||
984 | cdns,<addr> | |
985 | Start an early, polled-mode console on a cadence serial | |
986 | port at the specified address. The cadence serial port | |
987 | must already be setup and configured. Options are not | |
988 | yet supported. | |
989 | ||
990 | uart[8250],io,<addr>[,options] | |
991 | uart[8250],mmio,<addr>[,options] | |
992 | uart[8250],mmio32,<addr>[,options] | |
993 | uart[8250],mmio32be,<addr>[,options] | |
994 | uart[8250],0x<addr>[,options] | |
995 | Start an early, polled-mode console on the 8250/16550 | |
996 | UART at the specified I/O port or MMIO address. | |
997 | MMIO inter-register address stride is either 8-bit | |
998 | (mmio) or 32-bit (mmio32 or mmio32be). | |
999 | If none of [io|mmio|mmio32|mmio32be], <addr> is assumed | |
1000 | to be equivalent to 'mmio'. 'options' are specified | |
1001 | in the same format described for "console=ttyS<n>"; if | |
1002 | unspecified, the h/w is not initialized. | |
1003 | ||
1004 | pl011,<addr> | |
1005 | Start an early, polled-mode console on a pl011 serial | |
1006 | port at the specified address. The pl011 serial port | |
1007 | must already be setup and configured. Options are not | |
1008 | yet supported. | |
1009 | ||
1010 | msm_serial,<addr> | |
1011 | Start an early, polled-mode console on an msm serial | |
1012 | port at the specified address. The serial port | |
1013 | must already be setup and configured. Options are not | |
1014 | yet supported. | |
1015 | ||
1016 | msm_serial_dm,<addr> | |
1017 | Start an early, polled-mode console on an msm serial | |
1018 | dm port at the specified address. The serial port | |
1019 | must already be setup and configured. Options are not | |
1020 | yet supported. | |
1021 | ||
1022 | smh Use ARM semihosting calls for early console. | |
1023 | ||
1024 | s3c2410,<addr> | |
1025 | s3c2412,<addr> | |
1026 | s3c2440,<addr> | |
1027 | s3c6400,<addr> | |
1028 | s5pv210,<addr> | |
1029 | exynos4210,<addr> | |
1030 | Use early console provided by serial driver available | |
1031 | on Samsung SoCs, requires selecting proper type and | |
1032 | a correct base address of the selected UART port. The | |
1033 | serial port must already be setup and configured. | |
1034 | Options are not yet supported. | |
1035 | ||
1036 | lpuart,<addr> | |
1037 | lpuart32,<addr> | |
1038 | Use early console provided by Freescale LP UART driver | |
1039 | found on Freescale Vybrid and QorIQ LS1021A processors. | |
1040 | A valid base address must be provided, and the serial | |
1041 | port must already be setup and configured. | |
1042 | ||
1043 | earlyprintk= [X86,SH,BLACKFIN,ARM,M68k] | |
1044 | earlyprintk=vga | |
1045 | earlyprintk=efi | |
1046 | earlyprintk=xen | |
1047 | earlyprintk=serial[,ttySn[,baudrate]] | |
1048 | earlyprintk=serial[,0x...[,baudrate]] | |
1049 | earlyprintk=ttySn[,baudrate] | |
1050 | earlyprintk=dbgp[debugController#] | |
1051 | earlyprintk=pciserial,bus:device.function[,baudrate] | |
1052 | ||
1053 | earlyprintk is useful when the kernel crashes before | |
1054 | the normal console is initialized. It is not enabled by | |
1055 | default because it has some cosmetic problems. | |
1056 | ||
1057 | Append ",keep" to not disable it when the real console | |
1058 | takes over. | |
1059 | ||
1060 | Only one of vga, efi, serial, or usb debug port can | |
1061 | be used at a time. | |
1062 | ||
1063 | Currently only ttyS0 and ttyS1 may be specified by | |
1064 | name. Other I/O ports may be explicitly specified | |
1065 | on some architectures (x86 and arm at least) by | |
1066 | replacing ttySn with an I/O port address, like this: | |
1067 | earlyprintk=serial,0x1008,115200 | |
1068 | You can find the port for a given device in | |
1069 | /proc/tty/driver/serial: | |
1070 | 2: uart:ST16650V2 port:00001008 irq:18 ... | |
1071 | ||
1072 | Interaction with the standard serial driver is not | |
1073 | very good. | |
1074 | ||
1075 | The VGA and EFI output is eventually overwritten by | |
1076 | the real console. | |
1077 | ||
1078 | The xen output can only be used by Xen PV guests. | |
1079 | ||
1080 | edac_report= [HW,EDAC] Control how to report EDAC event | |
1081 | Format: {"on" | "off" | "force"} | |
1082 | on: enable EDAC to report H/W event. May be overridden | |
1083 | by other higher priority error reporting module. | |
1084 | off: disable H/W event reporting through EDAC. | |
1085 | force: enforce the use of EDAC to report H/W event. | |
1086 | default: on. | |
1087 | ||
1088 | ekgdboc= [X86,KGDB] Allow early kernel console debugging | |
1089 | ekgdboc=kbd | |
1090 | ||
1091 | This is designed to be used in conjunction with | |
1092 | the boot argument: earlyprintk=vga | |
1093 | ||
1094 | edd= [EDD] | |
1095 | Format: {"off" | "on" | "skip[mbr]"} | |
1096 | ||
1097 | efi= [EFI] | |
1098 | Format: { "old_map", "nochunk", "noruntime", "debug" } | |
1099 | old_map [X86-64]: switch to the old ioremap-based EFI | |
1100 | runtime services mapping. 32-bit still uses this one by | |
1101 | default. | |
1102 | nochunk: disable reading files in "chunks" in the EFI | |
1103 | boot stub, as chunking can cause problems with some | |
1104 | firmware implementations. | |
1105 | noruntime : disable EFI runtime services support | |
1106 | debug: enable misc debug output | |
1107 | ||
1108 | efi_no_storage_paranoia [EFI; X86] | |
1109 | Using this parameter you can use more than 50% of | |
1110 | your efi variable storage. Use this parameter only if | |
1111 | you are really sure that your UEFI does sane gc and | |
1112 | fulfills the spec otherwise your board may brick. | |
1113 | ||
1114 | efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86] | |
1115 | Add arbitrary attribute to specific memory range by | |
1116 | updating original EFI memory map. | |
1117 | Region of memory which aa attribute is added to is | |
1118 | from ss to ss+nn. | |
1119 | If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000 | |
1120 | is specified, EFI_MEMORY_MORE_RELIABLE(0x10000) | |
1121 | attribute is added to range 0x100000000-0x180000000 and | |
1122 | 0x10a0000000-0x1120000000. | |
1123 | ||
1124 | Using this parameter you can do debugging of EFI memmap | |
1125 | related feature. For example, you can do debugging of | |
1126 | Address Range Mirroring feature even if your box | |
1127 | doesn't support it. | |
1128 | ||
1129 | eisa_irq_edge= [PARISC,HW] | |
1130 | See header of drivers/parisc/eisa.c. | |
1131 | ||
1132 | elanfreq= [X86-32] | |
1133 | See comment before function elanfreq_setup() in | |
1134 | arch/x86/kernel/cpu/cpufreq/elanfreq.c. | |
1135 | ||
1136 | elevator= [IOSCHED] | |
1137 | Format: {"cfq" | "deadline" | "noop"} | |
1138 | See Documentation/block/cfq-iosched.txt and | |
1139 | Documentation/block/deadline-iosched.txt for details. | |
1140 | ||
1141 | elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] | |
1142 | Specifies physical address of start of kernel core | |
1143 | image elf header and optionally the size. Generally | |
1144 | kexec loader will pass this option to capture kernel. | |
1145 | See Documentation/kdump/kdump.txt for details. | |
1146 | ||
1147 | enable_mtrr_cleanup [X86] | |
1148 | The kernel tries to adjust MTRR layout from continuous | |
1149 | to discrete, to make X server driver able to add WB | |
1150 | entry later. This parameter enables that. | |
1151 | ||
1152 | enable_timer_pin_1 [X86] | |
1153 | Enable PIN 1 of APIC timer | |
1154 | Can be useful to work around chipset bugs | |
1155 | (in particular on some ATI chipsets). | |
1156 | The kernel tries to set a reasonable default. | |
1157 | ||
1158 | enforcing [SELINUX] Set initial enforcing status. | |
1159 | Format: {"0" | "1"} | |
1160 | See security/selinux/Kconfig help text. | |
1161 | 0 -- permissive (log only, no denials). | |
1162 | 1 -- enforcing (deny and log). | |
1163 | Default value is 0. | |
1164 | Value can be changed at runtime via /selinux/enforce. | |
1165 | ||
1166 | erst_disable [ACPI] | |
1167 | Disable Error Record Serialization Table (ERST) | |
1168 | support. | |
1169 | ||
1170 | ether= [HW,NET] Ethernet cards parameters | |
1171 | This option is obsoleted by the "netdev=" option, which | |
1172 | has equivalent usage. See its documentation for details. | |
1173 | ||
1174 | evm= [EVM] | |
1175 | Format: { "fix" } | |
1176 | Permit 'security.evm' to be updated regardless of | |
1177 | current integrity status. | |
1178 | ||
1179 | failslab= | |
1180 | fail_page_alloc= | |
1181 | fail_make_request=[KNL] | |
1182 | General fault injection mechanism. | |
1183 | Format: <interval>,<probability>,<space>,<times> | |
1184 | See also Documentation/fault-injection/. | |
1185 | ||
1186 | floppy= [HW] | |
1187 | See Documentation/blockdev/floppy.txt. | |
1188 | ||
1189 | force_pal_cache_flush | |
1190 | [IA-64] Avoid check_sal_cache_flush which may hang on | |
1191 | buggy SAL_CACHE_FLUSH implementations. Using this | |
1192 | parameter will force ia64_sal_cache_flush to call | |
1193 | ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. | |
1194 | ||
1195 | forcepae [X86-32] | |
1196 | Forcefully enable Physical Address Extension (PAE). | |
1197 | Many Pentium M systems disable PAE but may have a | |
1198 | functionally usable PAE implementation. | |
1199 | Warning: use of this parameter will taint the kernel | |
1200 | and may cause unknown problems. | |
1201 | ||
1202 | ftrace=[tracer] | |
1203 | [FTRACE] will set and start the specified tracer | |
1204 | as early as possible in order to facilitate early | |
1205 | boot debugging. | |
1206 | ||
1207 | ftrace_dump_on_oops[=orig_cpu] | |
1208 | [FTRACE] will dump the trace buffers on oops. | |
1209 | If no parameter is passed, ftrace will dump | |
1210 | buffers of all CPUs, but if you pass orig_cpu, it will | |
1211 | dump only the buffer of the CPU that triggered the | |
1212 | oops. | |
1213 | ||
1214 | ftrace_filter=[function-list] | |
1215 | [FTRACE] Limit the functions traced by the function | |
1216 | tracer at boot up. function-list is a comma separated | |
1217 | list of functions. This list can be changed at run | |
1218 | time by the set_ftrace_filter file in the debugfs | |
1219 | tracing directory. | |
1220 | ||
1221 | ftrace_notrace=[function-list] | |
1222 | [FTRACE] Do not trace the functions specified in | |
1223 | function-list. This list can be changed at run time | |
1224 | by the set_ftrace_notrace file in the debugfs | |
1225 | tracing directory. | |
1226 | ||
1227 | ftrace_graph_filter=[function-list] | |
1228 | [FTRACE] Limit the top level callers functions traced | |
1229 | by the function graph tracer at boot up. | |
1230 | function-list is a comma separated list of functions | |
1231 | that can be changed at run time by the | |
1232 | set_graph_function file in the debugfs tracing directory. | |
1233 | ||
1234 | ftrace_graph_notrace=[function-list] | |
1235 | [FTRACE] Do not trace from the functions specified in | |
1236 | function-list. This list is a comma separated list of | |
1237 | functions that can be changed at run time by the | |
1238 | set_graph_notrace file in the debugfs tracing directory. | |
1239 | ||
1240 | gamecon.map[2|3]= | |
1241 | [HW,JOY] Multisystem joystick and NES/SNES/PSX pad | |
1242 | support via parallel port (up to 5 devices per port) | |
1243 | Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> | |
1244 | See also Documentation/input/joystick-parport.txt | |
1245 | ||
1246 | gamma= [HW,DRM] | |
1247 | ||
1248 | gart_fix_e820= [X86_64] disable the fix e820 for K8 GART | |
1249 | Format: off | on | |
1250 | default: on | |
1251 | ||
1252 | gcov_persist= [GCOV] When non-zero (default), profiling data for | |
1253 | kernel modules is saved and remains accessible via | |
1254 | debugfs, even when the module is unloaded/reloaded. | |
1255 | When zero, profiling data is discarded and associated | |
1256 | debugfs files are removed at module unload time. | |
1257 | ||
1258 | gpt [EFI] Forces disk with valid GPT signature but | |
1259 | invalid Protective MBR to be treated as GPT. If the | |
1260 | primary GPT is corrupted, it enables the backup/alternate | |
1261 | GPT to be used instead. | |
1262 | ||
1263 | grcan.enable0= [HW] Configuration of physical interface 0. Determines | |
1264 | the "Enable 0" bit of the configuration register. | |
1265 | Format: 0 | 1 | |
1266 | Default: 0 | |
1267 | grcan.enable1= [HW] Configuration of physical interface 1. Determines | |
1268 | the "Enable 0" bit of the configuration register. | |
1269 | Format: 0 | 1 | |
1270 | Default: 0 | |
1271 | grcan.select= [HW] Select which physical interface to use. | |
1272 | Format: 0 | 1 | |
1273 | Default: 0 | |
1274 | grcan.txsize= [HW] Sets the size of the tx buffer. | |
1275 | Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0. | |
1276 | Default: 1024 | |
1277 | grcan.rxsize= [HW] Sets the size of the rx buffer. | |
1278 | Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. | |
1279 | Default: 1024 | |
1280 | ||
1281 | hardlockup_all_cpu_backtrace= | |
1282 | [KNL] Should the hard-lockup detector generate | |
1283 | backtraces on all cpus. | |
1284 | Format: <integer> | |
1285 | ||
1286 | hashdist= [KNL,NUMA] Large hashes allocated during boot | |
1287 | are distributed across NUMA nodes. Defaults on | |
1288 | for 64-bit NUMA, off otherwise. | |
1289 | Format: 0 | 1 (for off | on) | |
1290 | ||
1291 | hcl= [IA-64] SGI's Hardware Graph compatibility layer | |
1292 | ||
1293 | hd= [EIDE] (E)IDE hard drive subsystem geometry | |
1294 | Format: <cyl>,<head>,<sect> | |
1295 | ||
1296 | hest_disable [ACPI] | |
1297 | Disable Hardware Error Source Table (HEST) support; | |
1298 | corresponding firmware-first mode error processing | |
1299 | logic will be disabled. | |
1300 | ||
1301 | highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact | |
1302 | size of <nn>. This works even on boxes that have no | |
1303 | highmem otherwise. This also works to reduce highmem | |
1304 | size on bigger boxes. | |
1305 | ||
1306 | highres= [KNL] Enable/disable high resolution timer mode. | |
1307 | Valid parameters: "on", "off" | |
1308 | Default: "on" | |
1309 | ||
1310 | hisax= [HW,ISDN] | |
1311 | See Documentation/isdn/README.HiSax. | |
1312 | ||
1313 | hlt [BUGS=ARM,SH] | |
1314 | ||
1315 | hpet= [X86-32,HPET] option to control HPET usage | |
1316 | Format: { enable (default) | disable | force | | |
1317 | verbose } | |
1318 | disable: disable HPET and use PIT instead | |
1319 | force: allow force enabled of undocumented chips (ICH4, | |
1320 | VIA, nVidia) | |
1321 | verbose: show contents of HPET registers during setup | |
1322 | ||
1323 | hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET | |
1324 | registers. Default set by CONFIG_HPET_MMAP_DEFAULT. | |
1325 | ||
1326 | hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. | |
1327 | hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. | |
1328 | On x86-64 and powerpc, this option can be specified | |
1329 | multiple times interleaved with hugepages= to reserve | |
1330 | huge pages of different sizes. Valid pages sizes on | |
1331 | x86-64 are 2M (when the CPU supports "pse") and 1G | |
1332 | (when the CPU supports the "pdpe1gb" cpuinfo flag). | |
1333 | ||
1334 | hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) | |
1335 | terminal devices. Valid values: 0..8 | |
1336 | hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. | |
1337 | If specified, z/VM IUCV HVC accepts connections | |
1338 | from listed z/VM user IDs only. | |
1339 | ||
1340 | hwthread_map= [METAG] Comma-separated list of Linux cpu id to | |
1341 | hardware thread id mappings. | |
1342 | Format: <cpu>:<hwthread> | |
1343 | ||
1344 | keep_bootcon [KNL] | |
1345 | Do not unregister boot console at start. This is only | |
1346 | useful for debugging when something happens in the window | |
1347 | between unregistering the boot console and initializing | |
1348 | the real console. | |
1349 | ||
1350 | i2c_bus= [HW] Override the default board specific I2C bus speed | |
1351 | or register an additional I2C bus that is not | |
1352 | registered from board initialization code. | |
1353 | Format: | |
1354 | <bus_id>,<clkrate> | |
1355 | ||
1356 | i8042.debug [HW] Toggle i8042 debug mode | |
1357 | i8042.unmask_kbd_data | |
1358 | [HW] Enable printing of interrupt data from the KBD port | |
1359 | (disabled by default, and as a pre-condition | |
1360 | requires that i8042.debug=1 be enabled) | |
1361 | i8042.direct [HW] Put keyboard port into non-translated mode | |
1362 | i8042.dumbkbd [HW] Pretend that controller can only read data from | |
1363 | keyboard and cannot control its state | |
1364 | (Don't attempt to blink the leds) | |
1365 | i8042.noaux [HW] Don't check for auxiliary (== mouse) port | |
1366 | i8042.nokbd [HW] Don't check/create keyboard port | |
1367 | i8042.noloop [HW] Disable the AUX Loopback command while probing | |
1368 | for the AUX port | |
1369 | i8042.nomux [HW] Don't check presence of an active multiplexing | |
1370 | controller | |
1371 | i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX | |
1372 | controllers | |
1373 | i8042.notimeout [HW] Ignore timeout condition signalled by controller | |
1374 | i8042.reset [HW] Reset the controller during init and cleanup | |
1375 | i8042.unlock [HW] Unlock (ignore) the keylock | |
1376 | i8042.kbdreset [HW] Reset device connected to KBD port | |
1377 | ||
1378 | i810= [HW,DRM] | |
1379 | ||
1380 | i8k.ignore_dmi [HW] Continue probing hardware even if DMI data | |
1381 | indicates that the driver is running on unsupported | |
1382 | hardware. | |
1383 | i8k.force [HW] Activate i8k driver even if SMM BIOS signature | |
1384 | does not match list of supported models. | |
1385 | i8k.power_status | |
1386 | [HW] Report power status in /proc/i8k | |
1387 | (disabled by default) | |
1388 | i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN | |
1389 | capability is set. | |
1390 | ||
1391 | i915.invert_brightness= | |
1392 | [DRM] Invert the sense of the variable that is used to | |
1393 | set the brightness of the panel backlight. Normally a | |
1394 | brightness value of 0 indicates backlight switched off, | |
1395 | and the maximum of the brightness value sets the backlight | |
1396 | to maximum brightness. If this parameter is set to 0 | |
1397 | (default) and the machine requires it, or this parameter | |
1398 | is set to 1, a brightness value of 0 sets the backlight | |
1399 | to maximum brightness, and the maximum of the brightness | |
1400 | value switches the backlight off. | |
1401 | -1 -- never invert brightness | |
1402 | 0 -- machine default | |
1403 | 1 -- force brightness inversion | |
1404 | ||
1405 | icn= [HW,ISDN] | |
1406 | Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] | |
1407 | ||
1408 | ide-core.nodma= [HW] (E)IDE subsystem | |
1409 | Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc | |
1410 | .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr | |
1411 | .cdrom .chs .ignore_cable are additional options | |
1412 | See Documentation/ide/ide.txt. | |
1413 | ||
1414 | ide-generic.probe-mask= [HW] (E)IDE subsystem | |
1415 | Format: <int> | |
1416 | Probe mask for legacy ISA IDE ports. Depending on | |
1417 | platform up to 6 ports are supported, enabled by | |
1418 | setting corresponding bits in the mask to 1. The | |
1419 | default value is 0x0, which has a special meaning. | |
1420 | On systems that have PCI, it triggers scanning the | |
1421 | PCI bus for the first and the second port, which | |
1422 | are then probed. On systems without PCI the value | |
1423 | of 0x0 enables probing the two first ports as if it | |
1424 | was 0x3. | |
1425 | ||
1426 | ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem | |
1427 | Claim all unknown PCI IDE storage controllers. | |
1428 | ||
1429 | idle= [X86] | |
1430 | Format: idle=poll, idle=halt, idle=nomwait | |
1431 | Poll forces a polling idle loop that can slightly | |
1432 | improve the performance of waking up a idle CPU, but | |
1433 | will use a lot of power and make the system run hot. | |
1434 | Not recommended. | |
1435 | idle=halt: Halt is forced to be used for CPU idle. | |
1436 | In such case C2/C3 won't be used again. | |
1437 | idle=nomwait: Disable mwait for CPU C-states | |
1438 | ||
1439 | ignore_loglevel [KNL] | |
1440 | Ignore loglevel setting - this will print /all/ | |
1441 | kernel messages to the console. Useful for debugging. | |
1442 | We also add it as printk module parameter, so users | |
1443 | could change it dynamically, usually by | |
1444 | /sys/module/printk/parameters/ignore_loglevel. | |
1445 | ||
1446 | ihash_entries= [KNL] | |
1447 | Set number of hash buckets for inode cache. | |
1448 | ||
1449 | ima_appraise= [IMA] appraise integrity measurements | |
1450 | Format: { "off" | "enforce" | "fix" | "log" } | |
1451 | default: "enforce" | |
1452 | ||
1453 | ima_appraise_tcb [IMA] | |
1454 | The builtin appraise policy appraises all files | |
1455 | owned by uid=0. | |
1456 | ||
1457 | ima_hash= [IMA] | |
1458 | Format: { md5 | sha1 | rmd160 | sha256 | sha384 | |
1459 | | sha512 | ... } | |
1460 | default: "sha1" | |
1461 | ||
1462 | The list of supported hash algorithms is defined | |
1463 | in crypto/hash_info.h. | |
1464 | ||
1465 | ima_policy= [IMA] | |
1466 | The builtin measurement policy to load during IMA | |
1467 | setup. Specyfing "tcb" as the value, measures all | |
1468 | programs exec'd, files mmap'd for exec, and all files | |
1469 | opened with the read mode bit set by either the | |
1470 | effective uid (euid=0) or uid=0. | |
1471 | Format: "tcb" | |
1472 | ||
1473 | ima_tcb [IMA] Deprecated. Use ima_policy= instead. | |
1474 | Load a policy which meets the needs of the Trusted | |
1475 | Computing Base. This means IMA will measure all | |
1476 | programs exec'd, files mmap'd for exec, and all files | |
1477 | opened for read by uid=0. | |
1478 | ||
1479 | ima_template= [IMA] | |
1480 | Select one of defined IMA measurements template formats. | |
1481 | Formats: { "ima" | "ima-ng" | "ima-sig" } | |
1482 | Default: "ima-ng" | |
1483 | ||
1484 | ima_template_fmt= | |
1485 | [IMA] Define a custom template format. | |
1486 | Format: { "field1|...|fieldN" } | |
1487 | ||
1488 | ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage | |
1489 | Format: <min_file_size> | |
1490 | Set the minimal file size for using asynchronous hash. | |
1491 | If left unspecified, ahash usage is disabled. | |
1492 | ||
1493 | ahash performance varies for different data sizes on | |
1494 | different crypto accelerators. This option can be used | |
1495 | to achieve the best performance for a particular HW. | |
1496 | ||
1497 | ima.ahash_bufsize= [IMA] Asynchronous hash buffer size | |
1498 | Format: <bufsize> | |
1499 | Set hashing buffer size. Default: 4k. | |
1500 | ||
1501 | ahash performance varies for different chunk sizes on | |
1502 | different crypto accelerators. This option can be used | |
1503 | to achieve best performance for particular HW. | |
1504 | ||
1505 | init= [KNL] | |
1506 | Format: <full_path> | |
1507 | Run specified binary instead of /sbin/init as init | |
1508 | process. | |
1509 | ||
1510 | initcall_debug [KNL] Trace initcalls as they are executed. Useful | |
1511 | for working out where the kernel is dying during | |
1512 | startup. | |
1513 | ||
1514 | initcall_blacklist= [KNL] Do not execute a comma-separated list of | |
1515 | initcall functions. Useful for debugging built-in | |
1516 | modules and initcalls. | |
1517 | ||
1518 | initrd= [BOOT] Specify the location of the initial ramdisk | |
1519 | ||
1520 | inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver | |
1521 | Format: <irq> | |
1522 | ||
1523 | int_pln_enable [x86] Enable power limit notification interrupt | |
1524 | ||
1525 | integrity_audit=[IMA] | |
1526 | Format: { "0" | "1" } | |
1527 | 0 -- basic integrity auditing messages. (Default) | |
1528 | 1 -- additional integrity auditing messages. | |
1529 | ||
1530 | intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option | |
1531 | on | |
1532 | Enable intel iommu driver. | |
1533 | off | |
1534 | Disable intel iommu driver. | |
1535 | igfx_off [Default Off] | |
1536 | By default, gfx is mapped as normal device. If a gfx | |
1537 | device has a dedicated DMAR unit, the DMAR unit is | |
1538 | bypassed by not enabling DMAR with this option. In | |
1539 | this case, gfx device will use physical address for | |
1540 | DMA. | |
1541 | forcedac [x86_64] | |
1542 | With this option iommu will not optimize to look | |
1543 | for io virtual address below 32-bit forcing dual | |
1544 | address cycle on pci bus for cards supporting greater | |
1545 | than 32-bit addressing. The default is to look | |
1546 | for translation below 32-bit and if not available | |
1547 | then look in the higher range. | |
1548 | strict [Default Off] | |
1549 | With this option on every unmap_single operation will | |
1550 | result in a hardware IOTLB flush operation as opposed | |
1551 | to batching them for performance. | |
1552 | sp_off [Default Off] | |
1553 | By default, super page will be supported if Intel IOMMU | |
1554 | has the capability. With this option, super page will | |
1555 | not be supported. | |
1556 | ecs_off [Default Off] | |
1557 | By default, extended context tables will be supported if | |
1558 | the hardware advertises that it has support both for the | |
1559 | extended tables themselves, and also PASID support. With | |
1560 | this option set, extended tables will not be used even | |
1561 | on hardware which claims to support them. | |
1562 | ||
1563 | intel_idle.max_cstate= [KNL,HW,ACPI,X86] | |
1564 | 0 disables intel_idle and fall back on acpi_idle. | |
1565 | 1 to 6 specify maximum depth of C-state. | |
1566 | ||
1567 | intel_pstate= [X86] | |
1568 | disable | |
1569 | Do not enable intel_pstate as the default | |
1570 | scaling driver for the supported processors | |
1571 | force | |
1572 | Enable intel_pstate on systems that prohibit it by default | |
1573 | in favor of acpi-cpufreq. Forcing the intel_pstate driver | |
1574 | instead of acpi-cpufreq may disable platform features, such | |
1575 | as thermal controls and power capping, that rely on ACPI | |
1576 | P-States information being indicated to OSPM and therefore | |
1577 | should be used with caution. This option does not work with | |
1578 | processors that aren't supported by the intel_pstate driver | |
1579 | or on platforms that use pcc-cpufreq instead of acpi-cpufreq. | |
1580 | no_hwp | |
1581 | Do not enable hardware P state control (HWP) | |
1582 | if available. | |
1583 | hwp_only | |
1584 | Only load intel_pstate on systems which support | |
1585 | hardware P state control (HWP) if available. | |
1586 | ||
1587 | intremap= [X86-64, Intel-IOMMU] | |
1588 | on enable Interrupt Remapping (default) | |
1589 | off disable Interrupt Remapping | |
1590 | nosid disable Source ID checking | |
1591 | no_x2apic_optout | |
1592 | BIOS x2APIC opt-out request will be ignored | |
1593 | nopost disable Interrupt Posting | |
1594 | ||
1595 | iomem= Disable strict checking of access to MMIO memory | |
1596 | strict regions from userspace. | |
1597 | relaxed | |
1598 | ||
1599 | iommu= [x86] | |
1600 | off | |
1601 | force | |
1602 | noforce | |
1603 | biomerge | |
1604 | panic | |
1605 | nopanic | |
1606 | merge | |
1607 | nomerge | |
1608 | forcesac | |
1609 | soft | |
1610 | pt [x86, IA-64] | |
1611 | nobypass [PPC/POWERNV] | |
1612 | Disable IOMMU bypass, using IOMMU for PCI devices. | |
1613 | ||
1614 | ||
1615 | io7= [HW] IO7 for Marvel based alpha systems | |
1616 | See comment before marvel_specify_io7 in | |
1617 | arch/alpha/kernel/core_marvel.c. | |
1618 | ||
1619 | io_delay= [X86] I/O delay method | |
1620 | 0x80 | |
1621 | Standard port 0x80 based delay | |
1622 | 0xed | |
1623 | Alternate port 0xed based delay (needed on some systems) | |
1624 | udelay | |
1625 | Simple two microseconds delay | |
1626 | none | |
1627 | No delay | |
1628 | ||
1629 | ip= [IP_PNP] | |
1630 | See Documentation/filesystems/nfs/nfsroot.txt. | |
1631 | ||
1632 | irqfixup [HW] | |
1633 | When an interrupt is not handled search all handlers | |
1634 | for it. Intended to get systems with badly broken | |
1635 | firmware running. | |
1636 | ||
1637 | irqpoll [HW] | |
1638 | When an interrupt is not handled search all handlers | |
1639 | for it. Also check all handlers each timer | |
1640 | interrupt. Intended to get systems with badly broken | |
1641 | firmware running. | |
1642 | ||
1643 | isapnp= [ISAPNP] | |
1644 | Format: <RDP>,<reset>,<pci_scan>,<verbosity> | |
1645 | ||
1646 | isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. | |
1647 | Format: | |
1648 | <cpu number>,...,<cpu number> | |
1649 | or | |
1650 | <cpu number>-<cpu number> | |
1651 | (must be a positive range in ascending order) | |
1652 | or a mixture | |
1653 | <cpu number>,...,<cpu number>-<cpu number> | |
1654 | ||
1655 | This option can be used to specify one or more CPUs | |
1656 | to isolate from the general SMP balancing and scheduling | |
1657 | algorithms. You can move a process onto or off an | |
1658 | "isolated" CPU via the CPU affinity syscalls or cpuset. | |
1659 | <cpu number> begins at 0 and the maximum value is | |
1660 | "number of CPUs in system - 1". | |
1661 | ||
1662 | This option is the preferred way to isolate CPUs. The | |
1663 | alternative -- manually setting the CPU mask of all | |
1664 | tasks in the system -- can cause problems and | |
1665 | suboptimal load balancer performance. | |
1666 | ||
1667 | iucv= [HW,NET] | |
1668 | ||
1669 | ivrs_ioapic [HW,X86_64] | |
1670 | Provide an override to the IOAPIC-ID<->DEVICE-ID | |
1671 | mapping provided in the IVRS ACPI table. For | |
1672 | example, to map IOAPIC-ID decimal 10 to | |
1673 | PCI device 00:14.0 write the parameter as: | |
1674 | ivrs_ioapic[10]=00:14.0 | |
1675 | ||
1676 | ivrs_hpet [HW,X86_64] | |
1677 | Provide an override to the HPET-ID<->DEVICE-ID | |
1678 | mapping provided in the IVRS ACPI table. For | |
1679 | example, to map HPET-ID decimal 0 to | |
1680 | PCI device 00:14.0 write the parameter as: | |
1681 | ivrs_hpet[0]=00:14.0 | |
1682 | ||
1683 | js= [HW,JOY] Analog joystick | |
1684 | See Documentation/input/joystick.txt. | |
1685 | ||
1686 | kaslr/nokaslr [X86] | |
1687 | Enable/disable kernel and module base offset ASLR | |
1688 | (Address Space Layout Randomization) if built into | |
1689 | the kernel. When CONFIG_HIBERNATION is selected, | |
1690 | kASLR is disabled by default. When kASLR is enabled, | |
1691 | hibernation will be disabled. | |
1692 | ||
1693 | keepinitrd [HW,ARM] | |
1694 | ||
1695 | kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter | |
1696 | specifies the amount of memory usable by the kernel | |
1697 | for non-movable allocations. The requested amount is | |
1698 | spread evenly throughout all nodes in the system. The | |
1699 | remaining memory in each node is used for Movable | |
1700 | pages. In the event, a node is too small to have both | |
1701 | kernelcore and Movable pages, kernelcore pages will | |
1702 | take priority and other nodes will have a larger number | |
1703 | of Movable pages. The Movable zone is used for the | |
1704 | allocation of pages that may be reclaimed or moved | |
1705 | by the page migration subsystem. This means that | |
1706 | HugeTLB pages may not be allocated from this zone. | |
1707 | Note that allocations like PTEs-from-HighMem still | |
1708 | use the HighMem zone if it exists, and the Normal | |
1709 | zone if it does not. | |
1710 | ||
1711 | kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. | |
1712 | Format: <Controller#>[,poll interval] | |
1713 | The controller # is the number of the ehci usb debug | |
1714 | port as it is probed via PCI. The poll interval is | |
1715 | optional and is the number seconds in between | |
1716 | each poll cycle to the debug port in case you need | |
1717 | the functionality for interrupting the kernel with | |
1718 | gdb or control-c on the dbgp connection. When | |
1719 | not using this parameter you use sysrq-g to break into | |
1720 | the kernel debugger. | |
1721 | ||
1722 | kgdboc= [KGDB,HW] kgdb over consoles. | |
1723 | Requires a tty driver that supports console polling, | |
1724 | or a supported polling keyboard driver (non-usb). | |
1725 | Serial only format: <serial_device>[,baud] | |
1726 | keyboard only format: kbd | |
1727 | keyboard and serial format: kbd,<serial_device>[,baud] | |
1728 | Optional Kernel mode setting: | |
1729 | kms, kbd format: kms,kbd | |
1730 | kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] | |
1731 | ||
1732 | kgdbwait [KGDB] Stop kernel execution and enter the | |
1733 | kernel debugger at the earliest opportunity. | |
1734 | ||
1735 | kmac= [MIPS] korina ethernet MAC address. | |
1736 | Configure the RouterBoard 532 series on-chip | |
1737 | Ethernet adapter MAC address. | |
1738 | ||
1739 | kmemleak= [KNL] Boot-time kmemleak enable/disable | |
1740 | Valid arguments: on, off | |
1741 | Default: on | |
1742 | Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, | |
1743 | the default is off. | |
1744 | ||
1745 | kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode | |
1746 | Valid arguments: 0, 1, 2 | |
1747 | kmemcheck=0 (disabled) | |
1748 | kmemcheck=1 (enabled) | |
1749 | kmemcheck=2 (one-shot mode) | |
1750 | Default: 2 (one-shot mode) | |
1751 | ||
1752 | kstack=N [X86] Print N words from the kernel stack | |
1753 | in oops dumps. | |
1754 | ||
1755 | kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. | |
1756 | Default is 0 (don't ignore, but inject #GP) | |
1757 | ||
1758 | kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit | |
1759 | KVM MMU at runtime. | |
1760 | Default is 0 (off) | |
1761 | ||
1762 | kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. | |
1763 | Default is 1 (enabled) | |
1764 | ||
1765 | kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) | |
1766 | for all guests. | |
1767 | Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. | |
1768 | ||
1769 | kvm-intel.ept= [KVM,Intel] Disable extended page tables | |
1770 | (virtualized MMU) support on capable Intel chips. | |
1771 | Default is 1 (enabled) | |
1772 | ||
1773 | kvm-intel.emulate_invalid_guest_state= | |
1774 | [KVM,Intel] Enable emulation of invalid guest states | |
1775 | Default is 0 (disabled) | |
1776 | ||
1777 | kvm-intel.flexpriority= | |
1778 | [KVM,Intel] Disable FlexPriority feature (TPR shadow). | |
1779 | Default is 1 (enabled) | |
1780 | ||
1781 | kvm-intel.nested= | |
1782 | [KVM,Intel] Enable VMX nesting (nVMX). | |
1783 | Default is 0 (disabled) | |
1784 | ||
1785 | kvm-intel.unrestricted_guest= | |
1786 | [KVM,Intel] Disable unrestricted guest feature | |
1787 | (virtualized real and unpaged mode) on capable | |
1788 | Intel chips. Default is 1 (enabled) | |
1789 | ||
1790 | kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification | |
1791 | feature (tagged TLBs) on capable Intel chips. | |
1792 | Default is 1 (enabled) | |
1793 | ||
1794 | l2cr= [PPC] | |
1795 | ||
1796 | l3cr= [PPC] | |
1797 | ||
1798 | lapic [X86-32,APIC] Enable the local APIC even if BIOS | |
1799 | disabled it. | |
1800 | ||
1801 | lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline | |
1802 | value for LAPIC timer one-shot implementation. Default | |
1803 | back to the programmable timer unit in the LAPIC. | |
1804 | ||
1805 | lapic_timer_c2_ok [X86,APIC] trust the local apic timer | |
1806 | in C2 power state. | |
1807 | ||
1808 | libata.dma= [LIBATA] DMA control | |
1809 | libata.dma=0 Disable all PATA and SATA DMA | |
1810 | libata.dma=1 PATA and SATA Disk DMA only | |
1811 | libata.dma=2 ATAPI (CDROM) DMA only | |
1812 | libata.dma=4 Compact Flash DMA only | |
1813 | Combinations also work, so libata.dma=3 enables DMA | |
1814 | for disks and CDROMs, but not CFs. | |
1815 | ||
1816 | libata.ignore_hpa= [LIBATA] Ignore HPA limit | |
1817 | libata.ignore_hpa=0 keep BIOS limits (default) | |
1818 | libata.ignore_hpa=1 ignore limits, using full disk | |
1819 | ||
1820 | libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume | |
1821 | when set. | |
1822 | Format: <int> | |
1823 | ||
1824 | libata.force= [LIBATA] Force configurations. The format is comma | |
1825 | separated list of "[ID:]VAL" where ID is | |
1826 | PORT[.DEVICE]. PORT and DEVICE are decimal numbers | |
1827 | matching port, link or device. Basically, it matches | |
1828 | the ATA ID string printed on console by libata. If | |
1829 | the whole ID part is omitted, the last PORT and DEVICE | |
1830 | values are used. If ID hasn't been specified yet, the | |
1831 | configuration applies to all ports, links and devices. | |
1832 | ||
1833 | If only DEVICE is omitted, the parameter applies to | |
1834 | the port and all links and devices behind it. DEVICE | |
1835 | number of 0 either selects the first device or the | |
1836 | first fan-out link behind PMP device. It does not | |
1837 | select the host link. DEVICE number of 15 selects the | |
1838 | host link and device attached to it. | |
1839 | ||
1840 | The VAL specifies the configuration to force. As long | |
1841 | as there's no ambiguity shortcut notation is allowed. | |
1842 | For example, both 1.5 and 1.5G would work for 1.5Gbps. | |
1843 | The following configurations can be forced. | |
1844 | ||
1845 | * Cable type: 40c, 80c, short40c, unk, ign or sata. | |
1846 | Any ID with matching PORT is used. | |
1847 | ||
1848 | * SATA link speed limit: 1.5Gbps or 3.0Gbps. | |
1849 | ||
1850 | * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. | |
1851 | udma[/][16,25,33,44,66,100,133] notation is also | |
1852 | allowed. | |
1853 | ||
1854 | * [no]ncq: Turn on or off NCQ. | |
1855 | ||
1856 | * [no]ncqtrim: Turn off queued DSM TRIM. | |
1857 | ||
1858 | * nohrst, nosrst, norst: suppress hard, soft | |
1859 | and both resets. | |
1860 | ||
1861 | * rstonce: only attempt one reset during | |
1862 | hot-unplug link recovery | |
1863 | ||
1864 | * dump_id: dump IDENTIFY data. | |
1865 | ||
1866 | * atapi_dmadir: Enable ATAPI DMADIR bridge support | |
1867 | ||
1868 | * disable: Disable this device. | |
1869 | ||
1870 | If there are multiple matching configurations changing | |
1871 | the same attribute, the last one is used. | |
1872 | ||
1873 | memblock=debug [KNL] Enable memblock debug messages. | |
1874 | ||
1875 | load_ramdisk= [RAM] List of ramdisks to load from floppy | |
1876 | See Documentation/blockdev/ramdisk.txt. | |
1877 | ||
1878 | lockd.nlm_grace_period=P [NFS] Assign grace period. | |
1879 | Format: <integer> | |
1880 | ||
1881 | lockd.nlm_tcpport=N [NFS] Assign TCP port. | |
1882 | Format: <integer> | |
1883 | ||
1884 | lockd.nlm_timeout=T [NFS] Assign timeout value. | |
1885 | Format: <integer> | |
1886 | ||
1887 | lockd.nlm_udpport=M [NFS] Assign UDP port. | |
1888 | Format: <integer> | |
1889 | ||
1890 | locktorture.nreaders_stress= [KNL] | |
1891 | Set the number of locking read-acquisition kthreads. | |
1892 | Defaults to being automatically set based on the | |
1893 | number of online CPUs. | |
1894 | ||
1895 | locktorture.nwriters_stress= [KNL] | |
1896 | Set the number of locking write-acquisition kthreads. | |
1897 | ||
1898 | locktorture.onoff_holdoff= [KNL] | |
1899 | Set time (s) after boot for CPU-hotplug testing. | |
1900 | ||
1901 | locktorture.onoff_interval= [KNL] | |
1902 | Set time (s) between CPU-hotplug operations, or | |
1903 | zero to disable CPU-hotplug testing. | |
1904 | ||
1905 | locktorture.shuffle_interval= [KNL] | |
1906 | Set task-shuffle interval (jiffies). Shuffling | |
1907 | tasks allows some CPUs to go into dyntick-idle | |
1908 | mode during the locktorture test. | |
1909 | ||
1910 | locktorture.shutdown_secs= [KNL] | |
1911 | Set time (s) after boot system shutdown. This | |
1912 | is useful for hands-off automated testing. | |
1913 | ||
1914 | locktorture.stat_interval= [KNL] | |
1915 | Time (s) between statistics printk()s. | |
1916 | ||
1917 | locktorture.stutter= [KNL] | |
1918 | Time (s) to stutter testing, for example, | |
1919 | specifying five seconds causes the test to run for | |
1920 | five seconds, wait for five seconds, and so on. | |
1921 | This tests the locking primitive's ability to | |
1922 | transition abruptly to and from idle. | |
1923 | ||
1924 | locktorture.torture_runnable= [BOOT] | |
1925 | Start locktorture running at boot time. | |
1926 | ||
1927 | locktorture.torture_type= [KNL] | |
1928 | Specify the locking implementation to test. | |
1929 | ||
1930 | locktorture.verbose= [KNL] | |
1931 | Enable additional printk() statements. | |
1932 | ||
1933 | logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver | |
1934 | Format: <irq> | |
1935 | ||
1936 | loglevel= All Kernel Messages with a loglevel smaller than the | |
1937 | console loglevel will be printed to the console. It can | |
1938 | also be changed with klogd or other programs. The | |
1939 | loglevels are defined as follows: | |
1940 | ||
1941 | 0 (KERN_EMERG) system is unusable | |
1942 | 1 (KERN_ALERT) action must be taken immediately | |
1943 | 2 (KERN_CRIT) critical conditions | |
1944 | 3 (KERN_ERR) error conditions | |
1945 | 4 (KERN_WARNING) warning conditions | |
1946 | 5 (KERN_NOTICE) normal but significant condition | |
1947 | 6 (KERN_INFO) informational | |
1948 | 7 (KERN_DEBUG) debug-level messages | |
1949 | ||
1950 | log_buf_len=n[KMG] Sets the size of the printk ring buffer, | |
1951 | in bytes. n must be a power of two and greater | |
1952 | than the minimal size. The minimal size is defined | |
1953 | by LOG_BUF_SHIFT kernel config parameter. There is | |
1954 | also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter | |
1955 | that allows to increase the default size depending on | |
1956 | the number of CPUs. See init/Kconfig for more details. | |
1957 | ||
1958 | logo.nologo [FB] Disables display of the built-in Linux logo. | |
1959 | This may be used to provide more screen space for | |
1960 | kernel log messages and is useful when debugging | |
1961 | kernel boot problems. | |
1962 | ||
1963 | lp=0 [LP] Specify parallel ports to use, e.g, | |
1964 | lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses | |
1965 | lp=reset first parallel port). 'lp=0' disables the | |
1966 | lp=auto printer driver. 'lp=reset' (which can be | |
1967 | specified in addition to the ports) causes | |
1968 | attached printers to be reset. Using | |
1969 | lp=port1,port2,... specifies the parallel ports | |
1970 | to associate lp devices with, starting with | |
1971 | lp0. A port specification may be 'none' to skip | |
1972 | that lp device, or a parport name such as | |
1973 | 'parport0'. Specifying 'lp=auto' instead of a | |
1974 | port specification list means that device IDs | |
1975 | from each port should be examined, to see if | |
1976 | an IEEE 1284-compliant printer is attached; if | |
1977 | so, the driver will manage that printer. | |
1978 | See also header of drivers/char/lp.c. | |
1979 | ||
1980 | lpj=n [KNL] | |
1981 | Sets loops_per_jiffy to given constant, thus avoiding | |
1982 | time-consuming boot-time autodetection (up to 250 ms per | |
1983 | CPU). 0 enables autodetection (default). To determine | |
1984 | the correct value for your kernel, boot with normal | |
1985 | autodetection and see what value is printed. Note that | |
1986 | on SMP systems the preset will be applied to all CPUs, | |
1987 | which is likely to cause problems if your CPUs need | |
1988 | significantly divergent settings. An incorrect value | |
1989 | will cause delays in the kernel to be wrong, leading to | |
1990 | unpredictable I/O errors and other breakage. Although | |
1991 | unlikely, in the extreme case this might damage your | |
1992 | hardware. | |
1993 | ||
1994 | ltpc= [NET] | |
1995 | Format: <io>,<irq>,<dma> | |
1996 | ||
1997 | machvec= [IA-64] Force the use of a particular machine-vector | |
1998 | (machvec) in a generic kernel. | |
1999 | Example: machvec=hpzx1_swiotlb | |
2000 | ||
2001 | machtype= [Loongson] Share the same kernel image file between different | |
2002 | yeeloong laptop. | |
2003 | Example: machtype=lemote-yeeloong-2f-7inch | |
2004 | ||
2005 | max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater | |
2006 | than or equal to this physical address is ignored. | |
2007 | ||
2008 | maxcpus= [SMP] Maximum number of processors that an SMP kernel | |
2009 | should make use of. maxcpus=n : n >= 0 limits the | |
2010 | kernel to using 'n' processors. n=0 is a special case, | |
2011 | it is equivalent to "nosmp", which also disables | |
2012 | the IO APIC. | |
2013 | ||
2014 | max_loop= [LOOP] The number of loop block devices that get | |
2015 | (loop.max_loop) unconditionally pre-created at init time. The default | |
2016 | number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead | |
2017 | of statically allocating a predefined number, loop | |
2018 | devices can be requested on-demand with the | |
2019 | /dev/loop-control interface. | |
2020 | ||
2021 | mce [X86-32] Machine Check Exception | |
2022 | ||
2023 | mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt | |
2024 | ||
2025 | md= [HW] RAID subsystems devices and level | |
2026 | See Documentation/md.txt. | |
2027 | ||
2028 | mdacon= [MDA] | |
2029 | Format: <first>,<last> | |
2030 | Specifies range of consoles to be captured by the MDA. | |
2031 | ||
2032 | mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory | |
2033 | Amount of memory to be used when the kernel is not able | |
2034 | to see the whole system memory or for test. | |
2035 | [X86] Work as limiting max address. Use together | |
2036 | with memmap= to avoid physical address space collisions. | |
2037 | Without memmap= PCI devices could be placed at addresses | |
2038 | belonging to unused RAM. | |
2039 | ||
2040 | mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel | |
2041 | memory. | |
2042 | ||
2043 | memchunk=nn[KMG] | |
2044 | [KNL,SH] Allow user to override the default size for | |
2045 | per-device physically contiguous DMA buffers. | |
2046 | ||
2047 | memmap=exactmap [KNL,X86] Enable setting of an exact | |
2048 | E820 memory map, as specified by the user. | |
2049 | Such memmap=exactmap lines can be constructed based on | |
2050 | BIOS output or other requirements. See the memmap=nn@ss | |
2051 | option description. | |
2052 | ||
2053 | memmap=nn[KMG]@ss[KMG] | |
2054 | [KNL] Force usage of a specific region of memory. | |
2055 | Region of memory to be used is from ss to ss+nn. | |
2056 | ||
2057 | memmap=nn[KMG]#ss[KMG] | |
2058 | [KNL,ACPI] Mark specific memory as ACPI data. | |
2059 | Region of memory to be marked is from ss to ss+nn. | |
2060 | ||
2061 | memmap=nn[KMG]$ss[KMG] | |
2062 | [KNL,ACPI] Mark specific memory as reserved. | |
2063 | Region of memory to be reserved is from ss to ss+nn. | |
2064 | Example: Exclude memory from 0x18690000-0x1869ffff | |
2065 | memmap=64K$0x18690000 | |
2066 | or | |
2067 | memmap=0x10000$0x18690000 | |
2068 | ||
2069 | memmap=nn[KMG]!ss[KMG] | |
2070 | [KNL,X86] Mark specific memory as protected. | |
2071 | Region of memory to be used, from ss to ss+nn. | |
2072 | The memory region may be marked as e820 type 12 (0xc) | |
2073 | and is NVDIMM or ADR memory. | |
2074 | ||
2075 | memory_corruption_check=0/1 [X86] | |
2076 | Some BIOSes seem to corrupt the first 64k of | |
2077 | memory when doing things like suspend/resume. | |
2078 | Setting this option will scan the memory | |
2079 | looking for corruption. Enabling this will | |
2080 | both detect corruption and prevent the kernel | |
2081 | from using the memory being corrupted. | |
2082 | However, its intended as a diagnostic tool; if | |
2083 | repeatable BIOS-originated corruption always | |
2084 | affects the same memory, you can use memmap= | |
2085 | to prevent the kernel from using that memory. | |
2086 | ||
2087 | memory_corruption_check_size=size [X86] | |
2088 | By default it checks for corruption in the low | |
2089 | 64k, making this memory unavailable for normal | |
2090 | use. Use this parameter to scan for | |
2091 | corruption in more or less memory. | |
2092 | ||
2093 | memory_corruption_check_period=seconds [X86] | |
2094 | By default it checks for corruption every 60 | |
2095 | seconds. Use this parameter to check at some | |
2096 | other rate. 0 disables periodic checking. | |
2097 | ||
2098 | memtest= [KNL,X86,ARM] Enable memtest | |
2099 | Format: <integer> | |
2100 | default : 0 <disable> | |
2101 | Specifies the number of memtest passes to be | |
2102 | performed. Each pass selects another test | |
2103 | pattern from a given set of patterns. Memtest | |
2104 | fills the memory with this pattern, validates | |
2105 | memory contents and reserves bad memory | |
2106 | regions that are detected. | |
2107 | ||
2108 | meye.*= [HW] Set MotionEye Camera parameters | |
2109 | See Documentation/video4linux/meye.txt. | |
2110 | ||
2111 | mfgpt_irq= [IA-32] Specify the IRQ to use for the | |
2112 | Multi-Function General Purpose Timers on AMD Geode | |
2113 | platforms. | |
2114 | ||
2115 | mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when | |
2116 | the BIOS has incorrectly applied a workaround. TinyBIOS | |
2117 | version 0.98 is known to be affected, 0.99 fixes the | |
2118 | problem by letting the user disable the workaround. | |
2119 | ||
2120 | mga= [HW,DRM] | |
2121 | ||
2122 | min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this | |
2123 | physical address is ignored. | |
2124 | ||
2125 | mini2440= [ARM,HW,KNL] | |
2126 | Format:[0..2][b][c][t] | |
2127 | Default: "0tb" | |
2128 | MINI2440 configuration specification: | |
2129 | 0 - The attached screen is the 3.5" TFT | |
2130 | 1 - The attached screen is the 7" TFT | |
2131 | 2 - The VGA Shield is attached (1024x768) | |
2132 | Leaving out the screen size parameter will not load | |
2133 | the TFT driver, and the framebuffer will be left | |
2134 | unconfigured. | |
2135 | b - Enable backlight. The TFT backlight pin will be | |
2136 | linked to the kernel VESA blanking code and a GPIO | |
2137 | LED. This parameter is not necessary when using the | |
2138 | VGA shield. | |
2139 | c - Enable the s3c camera interface. | |
2140 | t - Reserved for enabling touchscreen support. The | |
2141 | touchscreen support is not enabled in the mainstream | |
2142 | kernel as of 2.6.30, a preliminary port can be found | |
2143 | in the "bleeding edge" mini2440 support kernel at | |
2144 | http://repo.or.cz/w/linux-2.6/mini2440.git | |
2145 | ||
2146 | mminit_loglevel= | |
2147 | [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this | |
2148 | parameter allows control of the logging verbosity for | |
2149 | the additional memory initialisation checks. A value | |
2150 | of 0 disables mminit logging and a level of 4 will | |
2151 | log everything. Information is printed at KERN_DEBUG | |
2152 | so loglevel=8 may also need to be specified. | |
2153 | ||
2154 | module.sig_enforce | |
2155 | [KNL] When CONFIG_MODULE_SIG is set, this means that | |
2156 | modules without (valid) signatures will fail to load. | |
2157 | Note that if CONFIG_MODULE_SIG_FORCE is set, that | |
2158 | is always true, so this option does nothing. | |
2159 | ||
2160 | mousedev.tap_time= | |
2161 | [MOUSE] Maximum time between finger touching and | |
2162 | leaving touchpad surface for touch to be considered | |
2163 | a tap and be reported as a left button click (for | |
2164 | touchpads working in absolute mode only). | |
2165 | Format: <msecs> | |
2166 | mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices | |
2167 | reporting absolute coordinates, such as tablets | |
2168 | mousedev.yres= [MOUSE] Vertical screen resolution, used for devices | |
2169 | reporting absolute coordinates, such as tablets | |
2170 | ||
2171 | movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter | |
2172 | is similar to kernelcore except it specifies the | |
2173 | amount of memory used for migratable allocations. | |
2174 | If both kernelcore and movablecore is specified, | |
2175 | then kernelcore will be at *least* the specified | |
2176 | value but may be more. If movablecore on its own | |
2177 | is specified, the administrator must be careful | |
2178 | that the amount of memory usable for all allocations | |
2179 | is not too small. | |
2180 | ||
2181 | movable_node [KNL,X86] Boot-time switch to enable the effects | |
2182 | of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details. | |
2183 | ||
2184 | MTD_Partition= [MTD] | |
2185 | Format: <name>,<region-number>,<size>,<offset> | |
2186 | ||
2187 | MTD_Region= [MTD] Format: | |
2188 | <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] | |
2189 | ||
2190 | mtdparts= [MTD] | |
2191 | See drivers/mtd/cmdlinepart.c. | |
2192 | ||
2193 | multitce=off [PPC] This parameter disables the use of the pSeries | |
2194 | firmware feature for updating multiple TCE entries | |
2195 | at a time. | |
2196 | ||
2197 | onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration | |
2198 | ||
2199 | Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] | |
2200 | ||
2201 | boundary - index of last SLC block on Flex-OneNAND. | |
2202 | The remaining blocks are configured as MLC blocks. | |
2203 | lock - Configure if Flex-OneNAND boundary should be locked. | |
2204 | Once locked, the boundary cannot be changed. | |
2205 | 1 indicates lock status, 0 indicates unlock status. | |
2206 | ||
2207 | mtdset= [ARM] | |
2208 | ARM/S3C2412 JIVE boot control | |
2209 | ||
2210 | See arch/arm/mach-s3c2412/mach-jive.c | |
2211 | ||
2212 | mtouchusb.raw_coordinates= | |
2213 | [HW] Make the MicroTouch USB driver use raw coordinates | |
2214 | ('y', default) or cooked coordinates ('n') | |
2215 | ||
2216 | mtrr_chunk_size=nn[KMG] [X86] | |
2217 | used for mtrr cleanup. It is largest continuous chunk | |
2218 | that could hold holes aka. UC entries. | |
2219 | ||
2220 | mtrr_gran_size=nn[KMG] [X86] | |
2221 | Used for mtrr cleanup. It is granularity of mtrr block. | |
2222 | Default is 1. | |
2223 | Large value could prevent small alignment from | |
2224 | using up MTRRs. | |
2225 | ||
2226 | mtrr_spare_reg_nr=n [X86] | |
2227 | Format: <integer> | |
2228 | Range: 0,7 : spare reg number | |
2229 | Default : 1 | |
2230 | Used for mtrr cleanup. It is spare mtrr entries number. | |
2231 | Set to 2 or more if your graphical card needs more. | |
2232 | ||
2233 | n2= [NET] SDL Inc. RISCom/N2 synchronous serial card | |
2234 | ||
2235 | netdev= [NET] Network devices parameters | |
2236 | Format: <irq>,<io>,<mem_start>,<mem_end>,<name> | |
2237 | Note that mem_start is often overloaded to mean | |
2238 | something different and driver-specific. | |
2239 | This usage is only documented in each driver source | |
2240 | file if at all. | |
2241 | ||
2242 | nf_conntrack.acct= | |
2243 | [NETFILTER] Enable connection tracking flow accounting | |
2244 | 0 to disable accounting | |
2245 | 1 to enable accounting | |
2246 | Default value is 0. | |
2247 | ||
2248 | nfsaddrs= [NFS] Deprecated. Use ip= instead. | |
2249 | See Documentation/filesystems/nfs/nfsroot.txt. | |
2250 | ||
2251 | nfsroot= [NFS] nfs root filesystem for disk-less boxes. | |
2252 | See Documentation/filesystems/nfs/nfsroot.txt. | |
2253 | ||
2254 | nfsrootdebug [NFS] enable nfsroot debugging messages. | |
2255 | See Documentation/filesystems/nfs/nfsroot.txt. | |
2256 | ||
2257 | nfs.callback_tcpport= | |
2258 | [NFS] set the TCP port on which the NFSv4 callback | |
2259 | channel should listen. | |
2260 | ||
2261 | nfs.cache_getent= | |
2262 | [NFS] sets the pathname to the program which is used | |
2263 | to update the NFS client cache entries. | |
2264 | ||
2265 | nfs.cache_getent_timeout= | |
2266 | [NFS] sets the timeout after which an attempt to | |
2267 | update a cache entry is deemed to have failed. | |
2268 | ||
2269 | nfs.idmap_cache_timeout= | |
2270 | [NFS] set the maximum lifetime for idmapper cache | |
2271 | entries. | |
2272 | ||
2273 | nfs.enable_ino64= | |
2274 | [NFS] enable 64-bit inode numbers. | |
2275 | If zero, the NFS client will fake up a 32-bit inode | |
2276 | number for the readdir() and stat() syscalls instead | |
2277 | of returning the full 64-bit number. | |
2278 | The default is to return 64-bit inode numbers. | |
2279 | ||
2280 | nfs.max_session_slots= | |
2281 | [NFSv4.1] Sets the maximum number of session slots | |
2282 | the client will attempt to negotiate with the server. | |
2283 | This limits the number of simultaneous RPC requests | |
2284 | that the client can send to the NFSv4.1 server. | |
2285 | Note that there is little point in setting this | |
2286 | value higher than the max_tcp_slot_table_limit. | |
2287 | ||
2288 | nfs.nfs4_disable_idmapping= | |
2289 | [NFSv4] When set to the default of '1', this option | |
2290 | ensures that both the RPC level authentication | |
2291 | scheme and the NFS level operations agree to use | |
2292 | numeric uids/gids if the mount is using the | |
2293 | 'sec=sys' security flavour. In effect it is | |
2294 | disabling idmapping, which can make migration from | |
2295 | legacy NFSv2/v3 systems to NFSv4 easier. | |
2296 | Servers that do not support this mode of operation | |
2297 | will be autodetected by the client, and it will fall | |
2298 | back to using the idmapper. | |
2299 | To turn off this behaviour, set the value to '0'. | |
2300 | nfs.nfs4_unique_id= | |
2301 | [NFS4] Specify an additional fixed unique ident- | |
2302 | ification string that NFSv4 clients can insert into | |
2303 | their nfs_client_id4 string. This is typically a | |
2304 | UUID that is generated at system install time. | |
2305 | ||
2306 | nfs.send_implementation_id = | |
2307 | [NFSv4.1] Send client implementation identification | |
2308 | information in exchange_id requests. | |
2309 | If zero, no implementation identification information | |
2310 | will be sent. | |
2311 | The default is to send the implementation identification | |
2312 | information. | |
2313 | ||
2314 | nfs.recover_lost_locks = | |
2315 | [NFSv4] Attempt to recover locks that were lost due | |
2316 | to a lease timeout on the server. Please note that | |
2317 | doing this risks data corruption, since there are | |
2318 | no guarantees that the file will remain unchanged | |
2319 | after the locks are lost. | |
2320 | If you want to enable the kernel legacy behaviour of | |
2321 | attempting to recover these locks, then set this | |
2322 | parameter to '1'. | |
2323 | The default parameter value of '0' causes the kernel | |
2324 | not to attempt recovery of lost locks. | |
2325 | ||
2326 | nfs4.layoutstats_timer = | |
2327 | [NFSv4.2] Change the rate at which the kernel sends | |
2328 | layoutstats to the pNFS metadata server. | |
2329 | ||
2330 | Setting this to value to 0 causes the kernel to use | |
2331 | whatever value is the default set by the layout | |
2332 | driver. A non-zero value sets the minimum interval | |
2333 | in seconds between layoutstats transmissions. | |
2334 | ||
2335 | nfsd.nfs4_disable_idmapping= | |
2336 | [NFSv4] When set to the default of '1', the NFSv4 | |
2337 | server will return only numeric uids and gids to | |
2338 | clients using auth_sys, and will accept numeric uids | |
2339 | and gids from such clients. This is intended to ease | |
2340 | migration from NFSv2/v3. | |
2341 | ||
2342 | objlayoutdriver.osd_login_prog= | |
2343 | [NFS] [OBJLAYOUT] sets the pathname to the program which | |
2344 | is used to automatically discover and login into new | |
2345 | osd-targets. Please see: | |
2346 | Documentation/filesystems/pnfs.txt for more explanations | |
2347 | ||
2348 | nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take | |
2349 | when a NMI is triggered. | |
2350 | Format: [state][,regs][,debounce][,die] | |
2351 | ||
2352 | nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels | |
2353 | Format: [panic,][nopanic,][num] | |
2354 | Valid num: 0 or 1 | |
2355 | 0 - turn hardlockup detector in nmi_watchdog off | |
2356 | 1 - turn hardlockup detector in nmi_watchdog on | |
2357 | When panic is specified, panic when an NMI watchdog | |
2358 | timeout occurs (or 'nopanic' to override the opposite | |
2359 | default). To disable both hard and soft lockup detectors, | |
2360 | please see 'nowatchdog'. | |
2361 | This is useful when you use a panic=... timeout and | |
2362 | need the box quickly up again. | |
2363 | ||
2364 | netpoll.carrier_timeout= | |
2365 | [NET] Specifies amount of time (in seconds) that | |
2366 | netpoll should wait for a carrier. By default netpoll | |
2367 | waits 4 seconds. | |
2368 | ||
2369 | no387 [BUGS=X86-32] Tells the kernel to use the 387 maths | |
2370 | emulation library even if a 387 maths coprocessor | |
2371 | is present. | |
2372 | ||
2373 | no_console_suspend | |
2374 | [HW] Never suspend the console | |
2375 | Disable suspending of consoles during suspend and | |
2376 | hibernate operations. Once disabled, debugging | |
2377 | messages can reach various consoles while the rest | |
2378 | of the system is being put to sleep (ie, while | |
2379 | debugging driver suspend/resume hooks). This may | |
2380 | not work reliably with all consoles, but is known | |
2381 | to work with serial and VGA consoles. | |
2382 | To facilitate more flexible debugging, we also add | |
2383 | console_suspend, a printk module parameter to control | |
2384 | it. Users could use console_suspend (usually | |
2385 | /sys/module/printk/parameters/console_suspend) to | |
2386 | turn on/off it dynamically. | |
2387 | ||
2388 | noaliencache [MM, NUMA, SLAB] Disables the allocation of alien | |
2389 | caches in the slab allocator. Saves per-node memory, | |
2390 | but will impact performance. | |
2391 | ||
2392 | noalign [KNL,ARM] | |
2393 | ||
2394 | noapic [SMP,APIC] Tells the kernel to not make use of any | |
2395 | IOAPICs that may be present in the system. | |
2396 | ||
2397 | noautogroup Disable scheduler automatic task group creation. | |
2398 | ||
2399 | nobats [PPC] Do not use BATs for mapping kernel lowmem | |
2400 | on "Classic" PPC cores. | |
2401 | ||
2402 | nocache [ARM] | |
2403 | ||
2404 | noclflush [BUGS=X86] Don't use the CLFLUSH instruction | |
2405 | ||
2406 | nodelayacct [KNL] Disable per-task delay accounting | |
2407 | ||
2408 | nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. | |
2409 | ||
2410 | nodsp [SH] Disable hardware DSP at boot time. | |
2411 | ||
2412 | noefi Disable EFI runtime services support. | |
2413 | ||
2414 | noexec [IA-64] | |
2415 | ||
2416 | noexec [X86] | |
2417 | On X86-32 available only on PAE configured kernels. | |
2418 | noexec=on: enable non-executable mappings (default) | |
2419 | noexec=off: disable non-executable mappings | |
2420 | ||
2421 | nosmap [X86] | |
2422 | Disable SMAP (Supervisor Mode Access Prevention) | |
2423 | even if it is supported by processor. | |
2424 | ||
2425 | nosmep [X86] | |
2426 | Disable SMEP (Supervisor Mode Execution Prevention) | |
2427 | even if it is supported by processor. | |
2428 | ||
2429 | noexec32 [X86-64] | |
2430 | This affects only 32-bit executables. | |
2431 | noexec32=on: enable non-executable mappings (default) | |
2432 | read doesn't imply executable mappings | |
2433 | noexec32=off: disable non-executable mappings | |
2434 | read implies executable mappings | |
2435 | ||
2436 | nofpu [MIPS,SH] Disable hardware FPU at boot time. | |
2437 | ||
2438 | nofxsr [BUGS=X86-32] Disables x86 floating point extended | |
2439 | register save and restore. The kernel will only save | |
2440 | legacy floating-point registers on task switch. | |
2441 | ||
2442 | nohugeiomap [KNL,x86] Disable kernel huge I/O mappings. | |
2443 | ||
2444 | noxsave [BUGS=X86] Disables x86 extended register state save | |
2445 | and restore using xsave. The kernel will fallback to | |
2446 | enabling legacy floating-point and sse state. | |
2447 | ||
2448 | noxsaveopt [X86] Disables xsaveopt used in saving x86 extended | |
2449 | register states. The kernel will fall back to use | |
2450 | xsave to save the states. By using this parameter, | |
2451 | performance of saving the states is degraded because | |
2452 | xsave doesn't support modified optimization while | |
2453 | xsaveopt supports it on xsaveopt enabled systems. | |
2454 | ||
2455 | noxsaves [X86] Disables xsaves and xrstors used in saving and | |
2456 | restoring x86 extended register state in compacted | |
2457 | form of xsave area. The kernel will fall back to use | |
2458 | xsaveopt and xrstor to save and restore the states | |
2459 | in standard form of xsave area. By using this | |
2460 | parameter, xsave area per process might occupy more | |
2461 | memory on xsaves enabled systems. | |
2462 | ||
2463 | nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or | |
2464 | wfi(ARM) instruction doesn't work correctly and not to | |
2465 | use it. This is also useful when using JTAG debugger. | |
2466 | ||
2467 | no_file_caps Tells the kernel not to honor file capabilities. The | |
2468 | only way then for a file to be executed with privilege | |
2469 | is to be setuid root or executed by root. | |
2470 | ||
2471 | nohalt [IA-64] Tells the kernel not to use the power saving | |
2472 | function PAL_HALT_LIGHT when idle. This increases | |
2473 | power-consumption. On the positive side, it reduces | |
2474 | interrupt wake-up latency, which may improve performance | |
2475 | in certain environments such as networked servers or | |
2476 | real-time systems. | |
2477 | ||
2478 | nohibernate [HIBERNATION] Disable hibernation and resume. | |
2479 | ||
2480 | nohz= [KNL] Boottime enable/disable dynamic ticks | |
2481 | Valid arguments: on, off | |
2482 | Default: on | |
2483 | ||
2484 | nohz_full= [KNL,BOOT] | |
2485 | In kernels built with CONFIG_NO_HZ_FULL=y, set | |
2486 | the specified list of CPUs whose tick will be stopped | |
2487 | whenever possible. The boot CPU will be forced outside | |
2488 | the range to maintain the timekeeping. | |
2489 | The CPUs in this range must also be included in the | |
2490 | rcu_nocbs= set. | |
2491 | ||
2492 | noiotrap [SH] Disables trapped I/O port accesses. | |
2493 | ||
2494 | noirqdebug [X86-32] Disables the code which attempts to detect and | |
2495 | disable unhandled interrupt sources. | |
2496 | ||
2497 | no_timer_check [X86,APIC] Disables the code which tests for | |
2498 | broken timer IRQ sources. | |
2499 | ||
2500 | noisapnp [ISAPNP] Disables ISA PnP code. | |
2501 | ||
2502 | noinitrd [RAM] Tells the kernel not to load any configured | |
2503 | initial RAM disk. | |
2504 | ||
2505 | nointremap [X86-64, Intel-IOMMU] Do not enable interrupt | |
2506 | remapping. | |
2507 | [Deprecated - use intremap=off] | |
2508 | ||
2509 | nointroute [IA-64] | |
2510 | ||
2511 | nojitter [IA-64] Disables jitter checking for ITC timers. | |
2512 | ||
2513 | no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver | |
2514 | ||
2515 | no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page | |
2516 | fault handling. | |
2517 | ||
2518 | no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. | |
2519 | steal time is computed, but won't influence scheduler | |
2520 | behaviour | |
2521 | ||
2522 | nolapic [X86-32,APIC] Do not enable or use the local APIC. | |
2523 | ||
2524 | nolapic_timer [X86-32,APIC] Do not use the local APIC timer. | |
2525 | ||
2526 | noltlbs [PPC] Do not use large page/tlb entries for kernel | |
2527 | lowmem mapping on PPC40x. | |
2528 | ||
2529 | nomca [IA-64] Disable machine check abort handling | |
2530 | ||
2531 | nomce [X86-32] Disable Machine Check Exception | |
2532 | ||
2533 | nomfgpt [X86-32] Disable Multi-Function General Purpose | |
2534 | Timer usage (for AMD Geode machines). | |
2535 | ||
2536 | nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to | |
2537 | shutdown the other cpus. Instead use the REBOOT_VECTOR | |
2538 | irq. | |
2539 | ||
2540 | nomodule Disable module load | |
2541 | ||
2542 | nopat [X86] Disable PAT (page attribute table extension of | |
2543 | pagetables) support. | |
2544 | ||
2545 | norandmaps Don't use address space randomization. Equivalent to | |
2546 | echo 0 > /proc/sys/kernel/randomize_va_space | |
2547 | ||
2548 | noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops | |
2549 | ||
2550 | noreplace-smp [X86-32,SMP] Don't replace SMP instructions | |
2551 | with UP alternatives | |
2552 | ||
2553 | nordrand [X86] Disable kernel use of the RDRAND and | |
2554 | RDSEED instructions even if they are supported | |
2555 | by the processor. RDRAND and RDSEED are still | |
2556 | available to user space applications. | |
2557 | ||
2558 | noresume [SWSUSP] Disables resume and restores original swap | |
2559 | space. | |
2560 | ||
2561 | no-scroll [VGA] Disables scrollback. | |
2562 | This is required for the Braillex ib80-piezo Braille | |
2563 | reader made by F.H. Papenmeier (Germany). | |
2564 | ||
2565 | nosbagart [IA-64] | |
2566 | ||
2567 | nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. | |
2568 | ||
2569 | nosmp [SMP] Tells an SMP kernel to act as a UP kernel, | |
2570 | and disable the IO APIC. legacy for "maxcpus=0". | |
2571 | ||
2572 | nosoftlockup [KNL] Disable the soft-lockup detector. | |
2573 | ||
2574 | nosync [HW,M68K] Disables sync negotiation for all devices. | |
2575 | ||
2576 | notsc [BUGS=X86-32] Disable Time Stamp Counter | |
2577 | ||
2578 | nousb [USB] Disable the USB subsystem | |
2579 | ||
2580 | nowatchdog [KNL] Disable both lockup detectors, i.e. | |
2581 | soft-lockup and NMI watchdog (hard-lockup). | |
2582 | ||
2583 | nowb [ARM] | |
2584 | ||
2585 | nox2apic [X86-64,APIC] Do not enable x2APIC mode. | |
2586 | ||
2587 | cpu0_hotplug [X86] Turn on CPU0 hotplug feature when | |
2588 | CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. | |
2589 | Some features depend on CPU0. Known dependencies are: | |
2590 | 1. Resume from suspend/hibernate depends on CPU0. | |
2591 | Suspend/hibernate will fail if CPU0 is offline and you | |
2592 | need to online CPU0 before suspend/hibernate. | |
2593 | 2. PIC interrupts also depend on CPU0. CPU0 can't be | |
2594 | removed if a PIC interrupt is detected. | |
2595 | It's said poweroff/reboot may depend on CPU0 on some | |
2596 | machines although I haven't seen such issues so far | |
2597 | after CPU0 is offline on a few tested machines. | |
2598 | If the dependencies are under your control, you can | |
2599 | turn on cpu0_hotplug. | |
2600 | ||
2601 | nptcg= [IA-64] Override max number of concurrent global TLB | |
2602 | purges which is reported from either PAL_VM_SUMMARY or | |
2603 | SAL PALO. | |
2604 | ||
2605 | nr_cpus= [SMP] Maximum number of processors that an SMP kernel | |
2606 | could support. nr_cpus=n : n >= 1 limits the kernel to | |
2607 | supporting 'n' processors. Later in runtime you can not | |
2608 | use hotplug cpu feature to put more cpu back to online. | |
2609 | just like you compile the kernel NR_CPUS=n | |
2610 | ||
2611 | nr_uarts= [SERIAL] maximum number of UARTs to be registered. | |
2612 | ||
2613 | numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. | |
2614 | Allowed values are enable and disable | |
2615 | ||
2616 | numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. | |
2617 | one of ['zone', 'node', 'default'] can be specified | |
2618 | This can be set from sysctl after boot. | |
2619 | See Documentation/sysctl/vm.txt for details. | |
2620 | ||
2621 | ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. | |
2622 | See Documentation/debugging-via-ohci1394.txt for more | |
2623 | info. | |
2624 | ||
2625 | olpc_ec_timeout= [OLPC] ms delay when issuing EC commands | |
2626 | Rather than timing out after 20 ms if an EC | |
2627 | command is not properly ACKed, override the length | |
2628 | of the timeout. We have interrupts disabled while | |
2629 | waiting for the ACK, so if this is set too high | |
2630 | interrupts *may* be lost! | |
2631 | ||
2632 | omap_mux= [OMAP] Override bootloader pin multiplexing. | |
2633 | Format: <mux_mode0.mode_name=value>... | |
2634 | For example, to override I2C bus2: | |
2635 | omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 | |
2636 | ||
2637 | oprofile.timer= [HW] | |
2638 | Use timer interrupt instead of performance counters | |
2639 | ||
2640 | oprofile.cpu_type= Force an oprofile cpu type | |
2641 | This might be useful if you have an older oprofile | |
2642 | userland or if you want common events. | |
2643 | Format: { arch_perfmon } | |
2644 | arch_perfmon: [X86] Force use of architectural | |
2645 | perfmon on Intel CPUs instead of the | |
2646 | CPU specific event set. | |
2647 | timer: [X86] Force use of architectural NMI | |
2648 | timer mode (see also oprofile.timer | |
2649 | for generic hr timer mode) | |
2650 | [s390] Force legacy basic mode sampling | |
2651 | (report cpu_type "timer") | |
2652 | ||
2653 | oops=panic Always panic on oopses. Default is to just kill the | |
2654 | process, but there is a small probability of | |
2655 | deadlocking the machine. | |
2656 | This will also cause panics on machine check exceptions. | |
2657 | Useful together with panic=30 to trigger a reboot. | |
2658 | ||
2659 | OSS [HW,OSS] | |
2660 | See Documentation/sound/oss/oss-parameters.txt | |
2661 | ||
2662 | page_owner= [KNL] Boot-time page_owner enabling option. | |
2663 | Storage of the information about who allocated | |
2664 | each page is disabled in default. With this switch, | |
2665 | we can turn it on. | |
2666 | on: enable the feature | |
2667 | ||
2668 | panic= [KNL] Kernel behaviour on panic: delay <timeout> | |
2669 | timeout > 0: seconds before rebooting | |
2670 | timeout = 0: wait forever | |
2671 | timeout < 0: reboot immediately | |
2672 | Format: <timeout> | |
2673 | ||
2674 | panic_on_warn panic() instead of WARN(). Useful to cause kdump | |
2675 | on a WARN(). | |
2676 | ||
2677 | crash_kexec_post_notifiers | |
2678 | Run kdump after running panic-notifiers and dumping | |
2679 | kmsg. This only for the users who doubt kdump always | |
2680 | succeeds in any situation. | |
2681 | Note that this also increases risks of kdump failure, | |
2682 | because some panic notifiers can make the crashed | |
2683 | kernel more unstable. | |
2684 | ||
2685 | parkbd.port= [HW] Parallel port number the keyboard adapter is | |
2686 | connected to, default is 0. | |
2687 | Format: <parport#> | |
2688 | parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, | |
2689 | 0 for XT, 1 for AT (default is AT). | |
2690 | Format: <mode> | |
2691 | ||
2692 | parport= [HW,PPT] Specify parallel ports. 0 disables. | |
2693 | Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } | |
2694 | Use 'auto' to force the driver to use any | |
2695 | IRQ/DMA settings detected (the default is to | |
2696 | ignore detected IRQ/DMA settings because of | |
2697 | possible conflicts). You can specify the base | |
2698 | address, IRQ, and DMA settings; IRQ and DMA | |
2699 | should be numbers, or 'auto' (for using detected | |
2700 | settings on that particular port), or 'nofifo' | |
2701 | (to avoid using a FIFO even if it is detected). | |
2702 | Parallel ports are assigned in the order they | |
2703 | are specified on the command line, starting | |
2704 | with parport0. | |
2705 | ||
2706 | parport_init_mode= [HW,PPT] | |
2707 | Configure VIA parallel port to operate in | |
2708 | a specific mode. This is necessary on Pegasos | |
2709 | computer where firmware has no options for setting | |
2710 | up parallel port mode and sets it to spp. | |
2711 | Currently this function knows 686a and 8231 chips. | |
2712 | Format: [spp|ps2|epp|ecp|ecpepp] | |
2713 | ||
2714 | pause_on_oops= | |
2715 | Halt all CPUs after the first oops has been printed for | |
2716 | the specified number of seconds. This is to be used if | |
2717 | your oopses keep scrolling off the screen. | |
2718 | ||
2719 | pcbit= [HW,ISDN] | |
2720 | ||
2721 | pcd. [PARIDE] | |
2722 | See header of drivers/block/paride/pcd.c. | |
2723 | See also Documentation/blockdev/paride.txt. | |
2724 | ||
2725 | pci=option[,option...] [PCI] various PCI subsystem options: | |
2726 | earlydump [X86] dump PCI config space before the kernel | |
2727 | changes anything | |
2728 | off [X86] don't probe for the PCI bus | |
2729 | bios [X86-32] force use of PCI BIOS, don't access | |
2730 | the hardware directly. Use this if your machine | |
2731 | has a non-standard PCI host bridge. | |
2732 | nobios [X86-32] disallow use of PCI BIOS, only direct | |
2733 | hardware access methods are allowed. Use this | |
2734 | if you experience crashes upon bootup and you | |
2735 | suspect they are caused by the BIOS. | |
2736 | conf1 [X86] Force use of PCI Configuration | |
2737 | Mechanism 1. | |
2738 | conf2 [X86] Force use of PCI Configuration | |
2739 | Mechanism 2. | |
2740 | noaer [PCIE] If the PCIEAER kernel config parameter is | |
2741 | enabled, this kernel boot option can be used to | |
2742 | disable the use of PCIE advanced error reporting. | |
2743 | nodomains [PCI] Disable support for multiple PCI | |
2744 | root domains (aka PCI segments, in ACPI-speak). | |
2745 | nommconf [X86] Disable use of MMCONFIG for PCI | |
2746 | Configuration | |
2747 | check_enable_amd_mmconf [X86] check for and enable | |
2748 | properly configured MMIO access to PCI | |
2749 | config space on AMD family 10h CPU | |
2750 | nomsi [MSI] If the PCI_MSI kernel config parameter is | |
2751 | enabled, this kernel boot option can be used to | |
2752 | disable the use of MSI interrupts system-wide. | |
2753 | noioapicquirk [APIC] Disable all boot interrupt quirks. | |
2754 | Safety option to keep boot IRQs enabled. This | |
2755 | should never be necessary. | |
2756 | ioapicreroute [APIC] Enable rerouting of boot IRQs to the | |
2757 | primary IO-APIC for bridges that cannot disable | |
2758 | boot IRQs. This fixes a source of spurious IRQs | |
2759 | when the system masks IRQs. | |
2760 | noioapicreroute [APIC] Disable workaround that uses the | |
2761 | boot IRQ equivalent of an IRQ that connects to | |
2762 | a chipset where boot IRQs cannot be disabled. | |
2763 | The opposite of ioapicreroute. | |
2764 | biosirq [X86-32] Use PCI BIOS calls to get the interrupt | |
2765 | routing table. These calls are known to be buggy | |
2766 | on several machines and they hang the machine | |
2767 | when used, but on other computers it's the only | |
2768 | way to get the interrupt routing table. Try | |
2769 | this option if the kernel is unable to allocate | |
2770 | IRQs or discover secondary PCI buses on your | |
2771 | motherboard. | |
2772 | rom [X86] Assign address space to expansion ROMs. | |
2773 | Use with caution as certain devices share | |
2774 | address decoders between ROMs and other | |
2775 | resources. | |
2776 | norom [X86] Do not assign address space to | |
2777 | expansion ROMs that do not already have | |
2778 | BIOS assigned address ranges. | |
2779 | nobar [X86] Do not assign address space to the | |
2780 | BARs that weren't assigned by the BIOS. | |
2781 | irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be | |
2782 | assigned automatically to PCI devices. You can | |
2783 | make the kernel exclude IRQs of your ISA cards | |
2784 | this way. | |
2785 | pirqaddr=0xAAAAA [X86] Specify the physical address | |
2786 | of the PIRQ table (normally generated | |
2787 | by the BIOS) if it is outside the | |
2788 | F0000h-100000h range. | |
2789 | lastbus=N [X86] Scan all buses thru bus #N. Can be | |
2790 | useful if the kernel is unable to find your | |
2791 | secondary buses and you want to tell it | |
2792 | explicitly which ones they are. | |
2793 | assign-busses [X86] Always assign all PCI bus | |
2794 | numbers ourselves, overriding | |
2795 | whatever the firmware may have done. | |
2796 | usepirqmask [X86] Honor the possible IRQ mask stored | |
2797 | in the BIOS $PIR table. This is needed on | |
2798 | some systems with broken BIOSes, notably | |
2799 | some HP Pavilion N5400 and Omnibook XE3 | |
2800 | notebooks. This will have no effect if ACPI | |
2801 | IRQ routing is enabled. | |
2802 | noacpi [X86] Do not use ACPI for IRQ routing | |
2803 | or for PCI scanning. | |
2804 | use_crs [X86] Use PCI host bridge window information | |
2805 | from ACPI. On BIOSes from 2008 or later, this | |
2806 | is enabled by default. If you need to use this, | |
2807 | please report a bug. | |
2808 | nocrs [X86] Ignore PCI host bridge windows from ACPI. | |
2809 | If you need to use this, please report a bug. | |
2810 | routeirq Do IRQ routing for all PCI devices. | |
2811 | This is normally done in pci_enable_device(), | |
2812 | so this option is a temporary workaround | |
2813 | for broken drivers that don't call it. | |
2814 | skip_isa_align [X86] do not align io start addr, so can | |
2815 | handle more pci cards | |
2816 | firmware [ARM] Do not re-enumerate the bus but instead | |
2817 | just use the configuration from the | |
2818 | bootloader. This is currently used on | |
2819 | IXP2000 systems where the bus has to be | |
2820 | configured a certain way for adjunct CPUs. | |
2821 | noearly [X86] Don't do any early type 1 scanning. | |
2822 | This might help on some broken boards which | |
2823 | machine check when some devices' config space | |
2824 | is read. But various workarounds are disabled | |
2825 | and some IOMMU drivers will not work. | |
2826 | bfsort Sort PCI devices into breadth-first order. | |
2827 | This sorting is done to get a device | |
2828 | order compatible with older (<= 2.4) kernels. | |
2829 | nobfsort Don't sort PCI devices into breadth-first order. | |
2830 | pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) | |
2831 | tuning and use the BIOS-configured MPS defaults. | |
2832 | pcie_bus_safe Set every device's MPS to the largest value | |
2833 | supported by all devices below the root complex. | |
2834 | pcie_bus_perf Set device MPS to the largest allowable MPS | |
2835 | based on its parent bus. Also set MRRS (Max | |
2836 | Read Request Size) to the largest supported | |
2837 | value (no larger than the MPS that the device | |
2838 | or bus can support) for best performance. | |
2839 | pcie_bus_peer2peer Set every device's MPS to 128B, which | |
2840 | every device is guaranteed to support. This | |
2841 | configuration allows peer-to-peer DMA between | |
2842 | any pair of devices, possibly at the cost of | |
2843 | reduced performance. This also guarantees | |
2844 | that hot-added devices will work. | |
2845 | cbiosize=nn[KMG] The fixed amount of bus space which is | |
2846 | reserved for the CardBus bridge's IO window. | |
2847 | The default value is 256 bytes. | |
2848 | cbmemsize=nn[KMG] The fixed amount of bus space which is | |
2849 | reserved for the CardBus bridge's memory | |
2850 | window. The default value is 64 megabytes. | |
2851 | resource_alignment= | |
2852 | Format: | |
2853 | [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] | |
2854 | Specifies alignment and device to reassign | |
2855 | aligned memory resources. | |
2856 | If <order of align> is not specified, | |
2857 | PAGE_SIZE is used as alignment. | |
2858 | PCI-PCI bridge can be specified, if resource | |
2859 | windows need to be expanded. | |
2860 | ecrc= Enable/disable PCIe ECRC (transaction layer | |
2861 | end-to-end CRC checking). | |
2862 | bios: Use BIOS/firmware settings. This is the | |
2863 | the default. | |
2864 | off: Turn ECRC off | |
2865 | on: Turn ECRC on. | |
2866 | hpiosize=nn[KMG] The fixed amount of bus space which is | |
2867 | reserved for hotplug bridge's IO window. | |
2868 | Default size is 256 bytes. | |
2869 | hpmemsize=nn[KMG] The fixed amount of bus space which is | |
2870 | reserved for hotplug bridge's memory window. | |
2871 | Default size is 2 megabytes. | |
2872 | realloc= Enable/disable reallocating PCI bridge resources | |
2873 | if allocations done by BIOS are too small to | |
2874 | accommodate resources required by all child | |
2875 | devices. | |
2876 | off: Turn realloc off | |
2877 | on: Turn realloc on | |
2878 | realloc same as realloc=on | |
2879 | noari do not use PCIe ARI. | |
2880 | pcie_scan_all Scan all possible PCIe devices. Otherwise we | |
2881 | only look for one device below a PCIe downstream | |
2882 | port. | |
2883 | ||
2884 | pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power | |
2885 | Management. | |
2886 | off Disable ASPM. | |
2887 | force Enable ASPM even on devices that claim not to support it. | |
2888 | WARNING: Forcing ASPM on may cause system lockups. | |
2889 | ||
2890 | pcie_hp= [PCIE] PCI Express Hotplug driver options: | |
2891 | nomsi Do not use MSI for PCI Express Native Hotplug (this | |
2892 | makes all PCIe ports use INTx for hotplug services). | |
2893 | ||
2894 | pcie_ports= [PCIE] PCIe ports handling: | |
2895 | auto Ask the BIOS whether or not to use native PCIe services | |
2896 | associated with PCIe ports (PME, hot-plug, AER). Use | |
2897 | them only if that is allowed by the BIOS. | |
2898 | native Use native PCIe services associated with PCIe ports | |
2899 | unconditionally. | |
2900 | compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe | |
2901 | ports driver. | |
2902 | ||
2903 | pcie_pme= [PCIE,PM] Native PCIe PME signaling options: | |
2904 | nomsi Do not use MSI for native PCIe PME signaling (this makes | |
2905 | all PCIe root ports use INTx for all services). | |
2906 | ||
2907 | pcmv= [HW,PCMCIA] BadgePAD 4 | |
2908 | ||
2909 | pd_ignore_unused | |
2910 | [PM] | |
2911 | Keep all power-domains already enabled by bootloader on, | |
2912 | even if no driver has claimed them. This is useful | |
2913 | for debug and development, but should not be | |
2914 | needed on a platform with proper driver support. | |
2915 | ||
2916 | pd. [PARIDE] | |
2917 | See Documentation/blockdev/paride.txt. | |
2918 | ||
2919 | pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at | |
2920 | boot time. | |
2921 | Format: { 0 | 1 } | |
2922 | See arch/parisc/kernel/pdc_chassis.c | |
2923 | ||
2924 | percpu_alloc= Select which percpu first chunk allocator to use. | |
2925 | Currently supported values are "embed" and "page". | |
2926 | Archs may support subset or none of the selections. | |
2927 | See comments in mm/percpu.c for details on each | |
2928 | allocator. This parameter is primarily for debugging | |
2929 | and performance comparison. | |
2930 | ||
2931 | pf. [PARIDE] | |
2932 | See Documentation/blockdev/paride.txt. | |
2933 | ||
2934 | pg. [PARIDE] | |
2935 | See Documentation/blockdev/paride.txt. | |
2936 | ||
2937 | pirq= [SMP,APIC] Manual mp-table setup | |
2938 | See Documentation/x86/i386/IO-APIC.txt. | |
2939 | ||
2940 | plip= [PPT,NET] Parallel port network link | |
2941 | Format: { parport<nr> | timid | 0 } | |
2942 | See also Documentation/parport.txt. | |
2943 | ||
2944 | pmtmr= [X86] Manual setup of pmtmr I/O Port. | |
2945 | Override pmtimer IOPort with a hex value. | |
2946 | e.g. pmtmr=0x508 | |
2947 | ||
2948 | pnp.debug=1 [PNP] | |
2949 | Enable PNP debug messages (depends on the | |
2950 | CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time | |
2951 | via /sys/module/pnp/parameters/debug. We always show | |
2952 | current resource usage; turning this on also shows | |
2953 | possible settings and some assignment information. | |
2954 | ||
2955 | pnpacpi= [ACPI] | |
2956 | { off } | |
2957 | ||
2958 | pnpbios= [ISAPNP] | |
2959 | { on | off | curr | res | no-curr | no-res } | |
2960 | ||
2961 | pnp_reserve_irq= | |
2962 | [ISAPNP] Exclude IRQs for the autoconfiguration | |
2963 | ||
2964 | pnp_reserve_dma= | |
2965 | [ISAPNP] Exclude DMAs for the autoconfiguration | |
2966 | ||
2967 | pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration | |
2968 | Ranges are in pairs (I/O port base and size). | |
2969 | ||
2970 | pnp_reserve_mem= | |
2971 | [ISAPNP] Exclude memory regions for the | |
2972 | autoconfiguration. | |
2973 | Ranges are in pairs (memory base and size). | |
2974 | ||
2975 | ports= [IP_VS_FTP] IPVS ftp helper module | |
2976 | Default is 21. | |
2977 | Up to 8 (IP_VS_APP_MAX_PORTS) ports | |
2978 | may be specified. | |
2979 | Format: <port>,<port>.... | |
2980 | ||
2981 | print-fatal-signals= | |
2982 | [KNL] debug: print fatal signals | |
2983 | ||
2984 | If enabled, warn about various signal handling | |
2985 | related application anomalies: too many signals, | |
2986 | too many POSIX.1 timers, fatal signals causing a | |
2987 | coredump - etc. | |
2988 | ||
2989 | If you hit the warning due to signal overflow, | |
2990 | you might want to try "ulimit -i unlimited". | |
2991 | ||
2992 | default: off. | |
2993 | ||
2994 | printk.always_kmsg_dump= | |
2995 | Trigger kmsg_dump for cases other than kernel oops or | |
2996 | panics | |
2997 | Format: <bool> (1/Y/y=enable, 0/N/n=disable) | |
2998 | default: disabled | |
2999 | ||
3000 | printk.time= Show timing data prefixed to each printk message line | |
3001 | Format: <bool> (1/Y/y=enable, 0/N/n=disable) | |
3002 | ||
3003 | processor.max_cstate= [HW,ACPI] | |
3004 | Limit processor to maximum C-state | |
3005 | max_cstate=9 overrides any DMI blacklist limit. | |
3006 | ||
3007 | processor.nocst [HW,ACPI] | |
3008 | Ignore the _CST method to determine C-states, | |
3009 | instead using the legacy FADT method | |
3010 | ||
3011 | profile= [KNL] Enable kernel profiling via /proc/profile | |
3012 | Format: [schedule,]<number> | |
3013 | Param: "schedule" - profile schedule points. | |
3014 | Param: <number> - step/bucket size as a power of 2 for | |
3015 | statistical time based profiling. | |
3016 | Param: "sleep" - profile D-state sleeping (millisecs). | |
3017 | Requires CONFIG_SCHEDSTATS | |
3018 | Param: "kvm" - profile VM exits. | |
3019 | ||
3020 | prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk | |
3021 | before loading. | |
3022 | See Documentation/blockdev/ramdisk.txt. | |
3023 | ||
3024 | psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to | |
3025 | probe for; one of (bare|imps|exps|lifebook|any). | |
3026 | psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports | |
3027 | per second. | |
3028 | psmouse.resetafter= [HW,MOUSE] | |
3029 | Try to reset the device after so many bad packets | |
3030 | (0 = never). | |
3031 | psmouse.resolution= | |
3032 | [HW,MOUSE] Set desired mouse resolution, in dpi. | |
3033 | psmouse.smartscroll= | |
3034 | [HW,MOUSE] Controls Logitech smartscroll autorepeat. | |
3035 | 0 = disabled, 1 = enabled (default). | |
3036 | ||
3037 | pstore.backend= Specify the name of the pstore backend to use | |
3038 | ||
3039 | pt. [PARIDE] | |
3040 | See Documentation/blockdev/paride.txt. | |
3041 | ||
3042 | pty.legacy_count= | |
3043 | [KNL] Number of legacy pty's. Overwrites compiled-in | |
3044 | default number. | |
3045 | ||
3046 | quiet [KNL] Disable most log messages | |
3047 | ||
3048 | r128= [HW,DRM] | |
3049 | ||
3050 | raid= [HW,RAID] | |
3051 | See Documentation/md.txt. | |
3052 | ||
3053 | ramdisk_blocksize= [RAM] | |
3054 | See Documentation/blockdev/ramdisk.txt. | |
3055 | ||
3056 | ramdisk_size= [RAM] Sizes of RAM disks in kilobytes | |
3057 | See Documentation/blockdev/ramdisk.txt. | |
3058 | ||
3059 | rcu_nocbs= [KNL] | |
3060 | In kernels built with CONFIG_RCU_NOCB_CPU=y, set | |
3061 | the specified list of CPUs to be no-callback CPUs. | |
3062 | Invocation of these CPUs' RCU callbacks will | |
3063 | be offloaded to "rcuox/N" kthreads created for | |
3064 | that purpose, where "x" is "b" for RCU-bh, "p" | |
3065 | for RCU-preempt, and "s" for RCU-sched, and "N" | |
3066 | is the CPU number. This reduces OS jitter on the | |
3067 | offloaded CPUs, which can be useful for HPC and | |
3068 | real-time workloads. It can also improve energy | |
3069 | efficiency for asymmetric multiprocessors. | |
3070 | ||
3071 | rcu_nocb_poll [KNL] | |
3072 | Rather than requiring that offloaded CPUs | |
3073 | (specified by rcu_nocbs= above) explicitly | |
3074 | awaken the corresponding "rcuoN" kthreads, | |
3075 | make these kthreads poll for callbacks. | |
3076 | This improves the real-time response for the | |
3077 | offloaded CPUs by relieving them of the need to | |
3078 | wake up the corresponding kthread, but degrades | |
3079 | energy efficiency by requiring that the kthreads | |
3080 | periodically wake up to do the polling. | |
3081 | ||
3082 | rcutree.blimit= [KNL] | |
3083 | Set maximum number of finished RCU callbacks to | |
3084 | process in one batch. | |
3085 | ||
3086 | rcutree.dump_tree= [KNL] | |
3087 | Dump the structure of the rcu_node combining tree | |
3088 | out at early boot. This is used for diagnostic | |
3089 | purposes, to verify correct tree setup. | |
3090 | ||
3091 | rcutree.gp_cleanup_delay= [KNL] | |
3092 | Set the number of jiffies to delay each step of | |
3093 | RCU grace-period cleanup. This only has effect | |
3094 | when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set. | |
3095 | ||
3096 | rcutree.gp_init_delay= [KNL] | |
3097 | Set the number of jiffies to delay each step of | |
3098 | RCU grace-period initialization. This only has | |
3099 | effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT | |
3100 | is set. | |
3101 | ||
3102 | rcutree.gp_preinit_delay= [KNL] | |
3103 | Set the number of jiffies to delay each step of | |
3104 | RCU grace-period pre-initialization, that is, | |
3105 | the propagation of recent CPU-hotplug changes up | |
3106 | the rcu_node combining tree. This only has effect | |
3107 | when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set. | |
3108 | ||
3109 | rcutree.rcu_fanout_exact= [KNL] | |
3110 | Disable autobalancing of the rcu_node combining | |
3111 | tree. This is used by rcutorture, and might | |
3112 | possibly be useful for architectures having high | |
3113 | cache-to-cache transfer latencies. | |
3114 | ||
3115 | rcutree.rcu_fanout_leaf= [KNL] | |
3116 | Change the number of CPUs assigned to each | |
3117 | leaf rcu_node structure. Useful for very | |
3118 | large systems, which will choose the value 64, | |
3119 | and for NUMA systems with large remote-access | |
3120 | latencies, which will choose a value aligned | |
3121 | with the appropriate hardware boundaries. | |
3122 | ||
3123 | rcutree.jiffies_till_sched_qs= [KNL] | |
3124 | Set required age in jiffies for a | |
3125 | given grace period before RCU starts | |
3126 | soliciting quiescent-state help from | |
3127 | rcu_note_context_switch(). | |
3128 | ||
3129 | rcutree.jiffies_till_first_fqs= [KNL] | |
3130 | Set delay from grace-period initialization to | |
3131 | first attempt to force quiescent states. | |
3132 | Units are jiffies, minimum value is zero, | |
3133 | and maximum value is HZ. | |
3134 | ||
3135 | rcutree.jiffies_till_next_fqs= [KNL] | |
3136 | Set delay between subsequent attempts to force | |
3137 | quiescent states. Units are jiffies, minimum | |
3138 | value is one, and maximum value is HZ. | |
3139 | ||
3140 | rcutree.kthread_prio= [KNL,BOOT] | |
3141 | Set the SCHED_FIFO priority of the RCU per-CPU | |
3142 | kthreads (rcuc/N). This value is also used for | |
3143 | the priority of the RCU boost threads (rcub/N) | |
3144 | and for the RCU grace-period kthreads (rcu_bh, | |
3145 | rcu_preempt, and rcu_sched). If RCU_BOOST is | |
3146 | set, valid values are 1-99 and the default is 1 | |
3147 | (the least-favored priority). Otherwise, when | |
3148 | RCU_BOOST is not set, valid values are 0-99 and | |
3149 | the default is zero (non-realtime operation). | |
3150 | ||
3151 | rcutree.rcu_nocb_leader_stride= [KNL] | |
3152 | Set the number of NOCB kthread groups, which | |
3153 | defaults to the square root of the number of | |
3154 | CPUs. Larger numbers reduces the wakeup overhead | |
3155 | on the per-CPU grace-period kthreads, but increases | |
3156 | that same overhead on each group's leader. | |
3157 | ||
3158 | rcutree.qhimark= [KNL] | |
3159 | Set threshold of queued RCU callbacks beyond which | |
3160 | batch limiting is disabled. | |
3161 | ||
3162 | rcutree.qlowmark= [KNL] | |
3163 | Set threshold of queued RCU callbacks below which | |
3164 | batch limiting is re-enabled. | |
3165 | ||
3166 | rcutree.rcu_idle_gp_delay= [KNL] | |
3167 | Set wakeup interval for idle CPUs that have | |
3168 | RCU callbacks (RCU_FAST_NO_HZ=y). | |
3169 | ||
3170 | rcutree.rcu_idle_lazy_gp_delay= [KNL] | |
3171 | Set wakeup interval for idle CPUs that have | |
3172 | only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). | |
3173 | Lazy RCU callbacks are those which RCU can | |
3174 | prove do nothing more than free memory. | |
3175 | ||
3176 | rcutorture.cbflood_inter_holdoff= [KNL] | |
3177 | Set holdoff time (jiffies) between successive | |
3178 | callback-flood tests. | |
3179 | ||
3180 | rcutorture.cbflood_intra_holdoff= [KNL] | |
3181 | Set holdoff time (jiffies) between successive | |
3182 | bursts of callbacks within a given callback-flood | |
3183 | test. | |
3184 | ||
3185 | rcutorture.cbflood_n_burst= [KNL] | |
3186 | Set the number of bursts making up a given | |
3187 | callback-flood test. Set this to zero to | |
3188 | disable callback-flood testing. | |
3189 | ||
3190 | rcutorture.cbflood_n_per_burst= [KNL] | |
3191 | Set the number of callbacks to be registered | |
3192 | in a given burst of a callback-flood test. | |
3193 | ||
3194 | rcutorture.fqs_duration= [KNL] | |
3195 | Set duration of force_quiescent_state bursts | |
3196 | in microseconds. | |
3197 | ||
3198 | rcutorture.fqs_holdoff= [KNL] | |
3199 | Set holdoff time within force_quiescent_state bursts | |
3200 | in microseconds. | |
3201 | ||
3202 | rcutorture.fqs_stutter= [KNL] | |
3203 | Set wait time between force_quiescent_state bursts | |
3204 | in seconds. | |
3205 | ||
3206 | rcutorture.gp_cond= [KNL] | |
3207 | Use conditional/asynchronous update-side | |
3208 | primitives, if available. | |
3209 | ||
3210 | rcutorture.gp_exp= [KNL] | |
3211 | Use expedited update-side primitives, if available. | |
3212 | ||
3213 | rcutorture.gp_normal= [KNL] | |
3214 | Use normal (non-expedited) asynchronous | |
3215 | update-side primitives, if available. | |
3216 | ||
3217 | rcutorture.gp_sync= [KNL] | |
3218 | Use normal (non-expedited) synchronous | |
3219 | update-side primitives, if available. If all | |
3220 | of rcutorture.gp_cond=, rcutorture.gp_exp=, | |
3221 | rcutorture.gp_normal=, and rcutorture.gp_sync= | |
3222 | are zero, rcutorture acts as if is interpreted | |
3223 | they are all non-zero. | |
3224 | ||
3225 | rcutorture.n_barrier_cbs= [KNL] | |
3226 | Set callbacks/threads for rcu_barrier() testing. | |
3227 | ||
3228 | rcutorture.nfakewriters= [KNL] | |
3229 | Set number of concurrent RCU writers. These just | |
3230 | stress RCU, they don't participate in the actual | |
3231 | test, hence the "fake". | |
3232 | ||
3233 | rcutorture.nreaders= [KNL] | |
3234 | Set number of RCU readers. The value -1 selects | |
3235 | N-1, where N is the number of CPUs. A value | |
3236 | "n" less than -1 selects N-n-2, where N is again | |
3237 | the number of CPUs. For example, -2 selects N | |
3238 | (the number of CPUs), -3 selects N+1, and so on. | |
3239 | ||
3240 | rcutorture.object_debug= [KNL] | |
3241 | Enable debug-object double-call_rcu() testing. | |
3242 | ||
3243 | rcutorture.onoff_holdoff= [KNL] | |
3244 | Set time (s) after boot for CPU-hotplug testing. | |
3245 | ||
3246 | rcutorture.onoff_interval= [KNL] | |
3247 | Set time (s) between CPU-hotplug operations, or | |
3248 | zero to disable CPU-hotplug testing. | |
3249 | ||
3250 | rcutorture.shuffle_interval= [KNL] | |
3251 | Set task-shuffle interval (s). Shuffling tasks | |
3252 | allows some CPUs to go into dyntick-idle mode | |
3253 | during the rcutorture test. | |
3254 | ||
3255 | rcutorture.shutdown_secs= [KNL] | |
3256 | Set time (s) after boot system shutdown. This | |
3257 | is useful for hands-off automated testing. | |
3258 | ||
3259 | rcutorture.stall_cpu= [KNL] | |
3260 | Duration of CPU stall (s) to test RCU CPU stall | |
3261 | warnings, zero to disable. | |
3262 | ||
3263 | rcutorture.stall_cpu_holdoff= [KNL] | |
3264 | Time to wait (s) after boot before inducing stall. | |
3265 | ||
3266 | rcutorture.stat_interval= [KNL] | |
3267 | Time (s) between statistics printk()s. | |
3268 | ||
3269 | rcutorture.stutter= [KNL] | |
3270 | Time (s) to stutter testing, for example, specifying | |
3271 | five seconds causes the test to run for five seconds, | |
3272 | wait for five seconds, and so on. This tests RCU's | |
3273 | ability to transition abruptly to and from idle. | |
3274 | ||
3275 | rcutorture.test_boost= [KNL] | |
3276 | Test RCU priority boosting? 0=no, 1=maybe, 2=yes. | |
3277 | "Maybe" means test if the RCU implementation | |
3278 | under test support RCU priority boosting. | |
3279 | ||
3280 | rcutorture.test_boost_duration= [KNL] | |
3281 | Duration (s) of each individual boost test. | |
3282 | ||
3283 | rcutorture.test_boost_interval= [KNL] | |
3284 | Interval (s) between each boost test. | |
3285 | ||
3286 | rcutorture.test_no_idle_hz= [KNL] | |
3287 | Test RCU's dyntick-idle handling. See also the | |
3288 | rcutorture.shuffle_interval parameter. | |
3289 | ||
3290 | rcutorture.torture_runnable= [BOOT] | |
3291 | Start rcutorture running at boot time. | |
3292 | ||
3293 | rcutorture.torture_type= [KNL] | |
3294 | Specify the RCU implementation to test. | |
3295 | ||
3296 | rcutorture.verbose= [KNL] | |
3297 | Enable additional printk() statements. | |
3298 | ||
3299 | rcupdate.rcu_expedited= [KNL] | |
3300 | Use expedited grace-period primitives, for | |
3301 | example, synchronize_rcu_expedited() instead | |
3302 | of synchronize_rcu(). This reduces latency, | |
3303 | but can increase CPU utilization, degrade | |
3304 | real-time latency, and degrade energy efficiency. | |
3305 | ||
3306 | rcupdate.rcu_cpu_stall_suppress= [KNL] | |
3307 | Suppress RCU CPU stall warning messages. | |
3308 | ||
3309 | rcupdate.rcu_cpu_stall_timeout= [KNL] | |
3310 | Set timeout for RCU CPU stall warning messages. | |
3311 | ||
3312 | rcupdate.rcu_task_stall_timeout= [KNL] | |
3313 | Set timeout in jiffies for RCU task stall warning | |
3314 | messages. Disable with a value less than or equal | |
3315 | to zero. | |
3316 | ||
3317 | rcupdate.rcu_self_test= [KNL] | |
3318 | Run the RCU early boot self tests | |
3319 | ||
3320 | rcupdate.rcu_self_test_bh= [KNL] | |
3321 | Run the RCU bh early boot self tests | |
3322 | ||
3323 | rcupdate.rcu_self_test_sched= [KNL] | |
3324 | Run the RCU sched early boot self tests | |
3325 | ||
3326 | rdinit= [KNL] | |
3327 | Format: <full_path> | |
3328 | Run specified binary instead of /init from the ramdisk, | |
3329 | used for early userspace startup. See initrd. | |
3330 | ||
3331 | reboot= [KNL] | |
3332 | Format (x86 or x86_64): | |
3333 | [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ | |
3334 | [[,]s[mp]#### \ | |
3335 | [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ | |
3336 | [[,]f[orce] | |
3337 | Where reboot_mode is one of warm (soft) or cold (hard) or gpio, | |
3338 | reboot_type is one of bios, acpi, kbd, triple, efi, or pci, | |
3339 | reboot_force is either force or not specified, | |
3340 | reboot_cpu is s[mp]#### with #### being the processor | |
3341 | to be used for rebooting. | |
3342 | ||
3343 | relax_domain_level= | |
3344 | [KNL, SMP] Set scheduler's default relax_domain_level. | |
3345 | See Documentation/cgroups/cpusets.txt. | |
3346 | ||
3347 | relative_sleep_states= | |
3348 | [SUSPEND] Use sleep state labeling where the deepest | |
3349 | state available other than hibernation is always "mem". | |
3350 | Format: { "0" | "1" } | |
3351 | 0 -- Traditional sleep state labels. | |
3352 | 1 -- Relative sleep state labels. | |
3353 | ||
3354 | reserve= [KNL,BUGS] Force the kernel to ignore some iomem area | |
3355 | ||
3356 | reservetop= [X86-32] | |
3357 | Format: nn[KMG] | |
3358 | Reserves a hole at the top of the kernel virtual | |
3359 | address space. | |
3360 | ||
3361 | reservelow= [X86] | |
3362 | Format: nn[K] | |
3363 | Set the amount of memory to reserve for BIOS at | |
3364 | the bottom of the address space. | |
3365 | ||
3366 | reset_devices [KNL] Force drivers to reset the underlying device | |
3367 | during initialization. | |
3368 | ||
3369 | resume= [SWSUSP] | |
3370 | Specify the partition device for software suspend | |
3371 | Format: | |
3372 | {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>} | |
3373 | ||
3374 | resume_offset= [SWSUSP] | |
3375 | Specify the offset from the beginning of the partition | |
3376 | given by "resume=" at which the swap header is located, | |
3377 | in <PAGE_SIZE> units (needed only for swap files). | |
3378 | See Documentation/power/swsusp-and-swap-files.txt | |
3379 | ||
3380 | resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to | |
3381 | read the resume files | |
3382 | ||
3383 | resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up. | |
3384 | Useful for devices that are detected asynchronously | |
3385 | (e.g. USB and MMC devices). | |
3386 | ||
3387 | hibernate= [HIBERNATION] | |
3388 | noresume Don't check if there's a hibernation image | |
3389 | present during boot. | |
3390 | nocompress Don't compress/decompress hibernation images. | |
3391 | no Disable hibernation and resume. | |
3392 | ||
3393 | retain_initrd [RAM] Keep initrd memory after extraction | |
3394 | ||
3395 | rfkill.default_state= | |
3396 | 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm, | |
3397 | etc. communication is blocked by default. | |
3398 | 1 Unblocked. | |
3399 | ||
3400 | rfkill.master_switch_mode= | |
3401 | 0 The "airplane mode" button does nothing. | |
3402 | 1 The "airplane mode" button toggles between everything | |
3403 | blocked and the previous configuration. | |
3404 | 2 The "airplane mode" button toggles between everything | |
3405 | blocked and everything unblocked. | |
3406 | ||
3407 | rhash_entries= [KNL,NET] | |
3408 | Set number of hash buckets for route cache | |
3409 | ||
3410 | ro [KNL] Mount root device read-only on boot | |
3411 | ||
3412 | root= [KNL] Root filesystem | |
3413 | See name_to_dev_t comment in init/do_mounts.c. | |
3414 | ||
3415 | rootdelay= [KNL] Delay (in seconds) to pause before attempting to | |
3416 | mount the root filesystem | |
3417 | ||
3418 | rootflags= [KNL] Set root filesystem mount option string | |
3419 | ||
3420 | rootfstype= [KNL] Set root filesystem type | |
3421 | ||
3422 | rootwait [KNL] Wait (indefinitely) for root device to show up. | |
3423 | Useful for devices that are detected asynchronously | |
3424 | (e.g. USB and MMC devices). | |
3425 | ||
3426 | rproc_mem=nn[KMG][@address] | |
3427 | [KNL,ARM,CMA] Remoteproc physical memory block. | |
3428 | Memory area to be used by remote processor image, | |
3429 | managed by CMA. | |
3430 | ||
3431 | rw [KNL] Mount root device read-write on boot | |
3432 | ||
3433 | S [KNL] Run init in single mode | |
3434 | ||
3435 | s390_iommu= [HW,S390] | |
3436 | Set s390 IOTLB flushing mode | |
3437 | strict | |
3438 | With strict flushing every unmap operation will result in | |
3439 | an IOTLB flush. Default is lazy flushing before reuse, | |
3440 | which is faster. | |
3441 | ||
3442 | sa1100ir [NET] | |
3443 | See drivers/net/irda/sa1100_ir.c. | |
3444 | ||
3445 | sbni= [NET] Granch SBNI12 leased line adapter | |
3446 | ||
3447 | sched_debug [KNL] Enables verbose scheduler debug messages. | |
3448 | ||
3449 | skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate | |
3450 | xtime_lock contention on larger systems, and/or RCU lock | |
3451 | contention on all systems with CONFIG_MAXSMP set. | |
3452 | Format: { "0" | "1" } | |
3453 | 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" | |
3454 | 1 -- enable. | |
3455 | Note: increases power consumption, thus should only be | |
3456 | enabled if running jitter sensitive (HPC/RT) workloads. | |
3457 | ||
3458 | security= [SECURITY] Choose a security module to enable at boot. | |
3459 | If this boot parameter is not specified, only the first | |
3460 | security module asking for security registration will be | |
3461 | loaded. An invalid security module name will be treated | |
3462 | as if no module has been chosen. | |
3463 | ||
3464 | selinux= [SELINUX] Disable or enable SELinux at boot time. | |
3465 | Format: { "0" | "1" } | |
3466 | See security/selinux/Kconfig help text. | |
3467 | 0 -- disable. | |
3468 | 1 -- enable. | |
3469 | Default value is set via kernel config option. | |
3470 | If enabled at boot time, /selinux/disable can be used | |
3471 | later to disable prior to initial policy load. | |
3472 | ||
3473 | apparmor= [APPARMOR] Disable or enable AppArmor at boot time | |
3474 | Format: { "0" | "1" } | |
3475 | See security/apparmor/Kconfig help text | |
3476 | 0 -- disable. | |
3477 | 1 -- enable. | |
3478 | Default value is set via kernel config option. | |
3479 | ||
3480 | serialnumber [BUGS=X86-32] | |
3481 | ||
3482 | shapers= [NET] | |
3483 | Maximal number of shapers. | |
3484 | ||
3485 | show_msr= [x86] show boot-time MSR settings | |
3486 | Format: { <integer> } | |
3487 | Show boot-time (BIOS-initialized) MSR settings. | |
3488 | The parameter means the number of CPUs to show, | |
3489 | for example 1 means boot CPU only. | |
3490 | ||
3491 | simeth= [IA-64] | |
3492 | simscsi= | |
3493 | ||
3494 | slram= [HW,MTD] | |
3495 | ||
3496 | slab_nomerge [MM] | |
3497 | Disable merging of slabs with similar size. May be | |
3498 | necessary if there is some reason to distinguish | |
3499 | allocs to different slabs. Debug options disable | |
3500 | merging on their own. | |
3501 | For more information see Documentation/vm/slub.txt. | |
3502 | ||
3503 | slab_max_order= [MM, SLAB] | |
3504 | Determines the maximum allowed order for slabs. | |
3505 | A high setting may cause OOMs due to memory | |
3506 | fragmentation. Defaults to 1 for systems with | |
3507 | more than 32MB of RAM, 0 otherwise. | |
3508 | ||
3509 | slub_debug[=options[,slabs]] [MM, SLUB] | |
3510 | Enabling slub_debug allows one to determine the | |
3511 | culprit if slab objects become corrupted. Enabling | |
3512 | slub_debug can create guard zones around objects and | |
3513 | may poison objects when not in use. Also tracks the | |
3514 | last alloc / free. For more information see | |
3515 | Documentation/vm/slub.txt. | |
3516 | ||
3517 | slub_max_order= [MM, SLUB] | |
3518 | Determines the maximum allowed order for slabs. | |
3519 | A high setting may cause OOMs due to memory | |
3520 | fragmentation. For more information see | |
3521 | Documentation/vm/slub.txt. | |
3522 | ||
3523 | slub_min_objects= [MM, SLUB] | |
3524 | The minimum number of objects per slab. SLUB will | |
3525 | increase the slab order up to slub_max_order to | |
3526 | generate a sufficiently large slab able to contain | |
3527 | the number of objects indicated. The higher the number | |
3528 | of objects the smaller the overhead of tracking slabs | |
3529 | and the less frequently locks need to be acquired. | |
3530 | For more information see Documentation/vm/slub.txt. | |
3531 | ||
3532 | slub_min_order= [MM, SLUB] | |
3533 | Determines the minimum page order for slabs. Must be | |
3534 | lower than slub_max_order. | |
3535 | For more information see Documentation/vm/slub.txt. | |
3536 | ||
3537 | slub_nomerge [MM, SLUB] | |
3538 | Same with slab_nomerge. This is supported for legacy. | |
3539 | See slab_nomerge for more information. | |
3540 | ||
3541 | smart2= [HW] | |
3542 | Format: <io1>[,<io2>[,...,<io8>]] | |
3543 | ||
3544 | smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices | |
3545 | smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port | |
3546 | smsc-ircc2.ircc_sir= [HW] SIR base I/O port | |
3547 | smsc-ircc2.ircc_fir= [HW] FIR base I/O port | |
3548 | smsc-ircc2.ircc_irq= [HW] IRQ line | |
3549 | smsc-ircc2.ircc_dma= [HW] DMA channel | |
3550 | smsc-ircc2.ircc_transceiver= [HW] Transceiver type: | |
3551 | 0: Toshiba Satellite 1800 (GP data pin select) | |
3552 | 1: Fast pin select (default) | |
3553 | 2: ATC IRMode | |
3554 | ||
3555 | softlockup_panic= | |
3556 | [KNL] Should the soft-lockup detector generate panics. | |
3557 | Format: <integer> | |
3558 | ||
3559 | softlockup_all_cpu_backtrace= | |
3560 | [KNL] Should the soft-lockup detector generate | |
3561 | backtraces on all cpus. | |
3562 | Format: <integer> | |
3563 | ||
3564 | sonypi.*= [HW] Sony Programmable I/O Control Device driver | |
3565 | See Documentation/laptops/sonypi.txt | |
3566 | ||
3567 | spia_io_base= [HW,MTD] | |
3568 | spia_fio_base= | |
3569 | spia_pedr= | |
3570 | spia_peddr= | |
3571 | ||
3572 | stacktrace [FTRACE] | |
3573 | Enabled the stack tracer on boot up. | |
3574 | ||
3575 | stacktrace_filter=[function-list] | |
3576 | [FTRACE] Limit the functions that the stack tracer | |
3577 | will trace at boot up. function-list is a comma separated | |
3578 | list of functions. This list can be changed at run | |
3579 | time by the stack_trace_filter file in the debugfs | |
3580 | tracing directory. Note, this enables stack tracing | |
3581 | and the stacktrace above is not needed. | |
3582 | ||
3583 | sti= [PARISC,HW] | |
3584 | Format: <num> | |
3585 | Set the STI (builtin display/keyboard on the HP-PARISC | |
3586 | machines) console (graphic card) which should be used | |
3587 | as the initial boot-console. | |
3588 | See also comment in drivers/video/console/sticore.c. | |
3589 | ||
3590 | sti_font= [HW] | |
3591 | See comment in drivers/video/console/sticore.c. | |
3592 | ||
3593 | stifb= [HW] | |
3594 | Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] | |
3595 | ||
3596 | sunrpc.min_resvport= | |
3597 | sunrpc.max_resvport= | |
3598 | [NFS,SUNRPC] | |
3599 | SunRPC servers often require that client requests | |
3600 | originate from a privileged port (i.e. a port in the | |
3601 | range 0 < portnr < 1024). | |
3602 | An administrator who wishes to reserve some of these | |
3603 | ports for other uses may adjust the range that the | |
3604 | kernel's sunrpc client considers to be privileged | |
3605 | using these two parameters to set the minimum and | |
3606 | maximum port values. | |
3607 | ||
3608 | sunrpc.pool_mode= | |
3609 | [NFS] | |
3610 | Control how the NFS server code allocates CPUs to | |
3611 | service thread pools. Depending on how many NICs | |
3612 | you have and where their interrupts are bound, this | |
3613 | option will affect which CPUs will do NFS serving. | |
3614 | Note: this parameter cannot be changed while the | |
3615 | NFS server is running. | |
3616 | ||
3617 | auto the server chooses an appropriate mode | |
3618 | automatically using heuristics | |
3619 | global a single global pool contains all CPUs | |
3620 | percpu one pool for each CPU | |
3621 | pernode one pool for each NUMA node (equivalent | |
3622 | to global on non-NUMA machines) | |
3623 | ||
3624 | sunrpc.tcp_slot_table_entries= | |
3625 | sunrpc.udp_slot_table_entries= | |
3626 | [NFS,SUNRPC] | |
3627 | Sets the upper limit on the number of simultaneous | |
3628 | RPC calls that can be sent from the client to a | |
3629 | server. Increasing these values may allow you to | |
3630 | improve throughput, but will also increase the | |
3631 | amount of memory reserved for use by the client. | |
3632 | ||
3633 | suspend.pm_test_delay= | |
3634 | [SUSPEND] | |
3635 | Sets the number of seconds to remain in a suspend test | |
3636 | mode before resuming the system (see | |
3637 | /sys/power/pm_test). Only available when CONFIG_PM_DEBUG | |
3638 | is set. Default value is 5. | |
3639 | ||
3640 | swapaccount=[0|1] | |
3641 | [KNL] Enable accounting of swap in memory resource | |
3642 | controller if no parameter or 1 is given or disable | |
3643 | it if 0 is given (See Documentation/cgroups/memory.txt) | |
3644 | ||
3645 | swiotlb= [ARM,IA-64,PPC,MIPS,X86] | |
3646 | Format: { <int> | force } | |
3647 | <int> -- Number of I/O TLB slabs | |
3648 | force -- force using of bounce buffers even if they | |
3649 | wouldn't be automatically used by the kernel | |
3650 | ||
3651 | switches= [HW,M68k] | |
3652 | ||
3653 | sysfs.deprecated=0|1 [KNL] | |
3654 | Enable/disable old style sysfs layout for old udev | |
3655 | on older distributions. When this option is enabled | |
3656 | very new udev will not work anymore. When this option | |
3657 | is disabled (or CONFIG_SYSFS_DEPRECATED not compiled) | |
3658 | in older udev will not work anymore. | |
3659 | Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in | |
3660 | the kernel configuration. | |
3661 | ||
3662 | sysrq_always_enabled | |
3663 | [KNL] | |
3664 | Ignore sysrq setting - this boot parameter will | |
3665 | neutralize any effect of /proc/sys/kernel/sysrq. | |
3666 | Useful for debugging. | |
3667 | ||
3668 | tcpmhash_entries= [KNL,NET] | |
3669 | Set the number of tcp_metrics_hash slots. | |
3670 | Default value is 8192 or 16384 depending on total | |
3671 | ram pages. This is used to specify the TCP metrics | |
3672 | cache size. See Documentation/networking/ip-sysctl.txt | |
3673 | "tcp_no_metrics_save" section for more details. | |
3674 | ||
3675 | tdfx= [HW,DRM] | |
3676 | ||
3677 | test_suspend= [SUSPEND][,N] | |
3678 | Specify "mem" (for Suspend-to-RAM) or "standby" (for | |
3679 | standby suspend) or "freeze" (for suspend type freeze) | |
3680 | as the system sleep state during system startup with | |
3681 | the optional capability to repeat N number of times. | |
3682 | The system is woken from this state using a | |
3683 | wakeup-capable RTC alarm. | |
3684 | ||
3685 | thash_entries= [KNL,NET] | |
3686 | Set number of hash buckets for TCP connection | |
3687 | ||
3688 | thermal.act= [HW,ACPI] | |
3689 | -1: disable all active trip points in all thermal zones | |
3690 | <degrees C>: override all lowest active trip points | |
3691 | ||
3692 | thermal.crt= [HW,ACPI] | |
3693 | -1: disable all critical trip points in all thermal zones | |
3694 | <degrees C>: override all critical trip points | |
3695 | ||
3696 | thermal.nocrt= [HW,ACPI] | |
3697 | Set to disable actions on ACPI thermal zone | |
3698 | critical and hot trip points. | |
3699 | ||
3700 | thermal.off= [HW,ACPI] | |
3701 | 1: disable ACPI thermal control | |
3702 | ||
3703 | thermal.psv= [HW,ACPI] | |
3704 | -1: disable all passive trip points | |
3705 | <degrees C>: override all passive trip points to this | |
3706 | value | |
3707 | ||
3708 | thermal.tzp= [HW,ACPI] | |
3709 | Specify global default ACPI thermal zone polling rate | |
3710 | <deci-seconds>: poll all this frequency | |
3711 | 0: no polling (default) | |
3712 | ||
3713 | threadirqs [KNL] | |
3714 | Force threading of all interrupt handlers except those | |
3715 | marked explicitly IRQF_NO_THREAD. | |
3716 | ||
3717 | tmem [KNL,XEN] | |
3718 | Enable the Transcendent memory driver if built-in. | |
3719 | ||
3720 | tmem.cleancache=0|1 [KNL, XEN] | |
3721 | Default is on (1). Disable the usage of the cleancache | |
3722 | API to send anonymous pages to the hypervisor. | |
3723 | ||
3724 | tmem.frontswap=0|1 [KNL, XEN] | |
3725 | Default is on (1). Disable the usage of the frontswap | |
3726 | API to send swap pages to the hypervisor. If disabled | |
3727 | the selfballooning and selfshrinking are force disabled. | |
3728 | ||
3729 | tmem.selfballooning=0|1 [KNL, XEN] | |
3730 | Default is on (1). Disable the driving of swap pages | |
3731 | to the hypervisor. | |
3732 | ||
3733 | tmem.selfshrinking=0|1 [KNL, XEN] | |
3734 | Default is on (1). Partial swapoff that immediately | |
3735 | transfers pages from Xen hypervisor back to the | |
3736 | kernel based on different criteria. | |
3737 | ||
3738 | topology= [S390] | |
3739 | Format: {off | on} | |
3740 | Specify if the kernel should make use of the cpu | |
3741 | topology information if the hardware supports this. | |
3742 | The scheduler will make use of this information and | |
3743 | e.g. base its process migration decisions on it. | |
3744 | Default is on. | |
3745 | ||
3746 | topology_updates= [KNL, PPC, NUMA] | |
3747 | Format: {off} | |
3748 | Specify if the kernel should ignore (off) | |
3749 | topology updates sent by the hypervisor to this | |
3750 | LPAR. | |
3751 | ||
3752 | tp720= [HW,PS2] | |
3753 | ||
3754 | tpm_suspend_pcr=[HW,TPM] | |
3755 | Format: integer pcr id | |
3756 | Specify that at suspend time, the tpm driver | |
3757 | should extend the specified pcr with zeros, | |
3758 | as a workaround for some chips which fail to | |
3759 | flush the last written pcr on TPM_SaveState. | |
3760 | This will guarantee that all the other pcrs | |
3761 | are saved. | |
3762 | ||
3763 | trace_buf_size=nn[KMG] | |
3764 | [FTRACE] will set tracing buffer size on each cpu. | |
3765 | ||
3766 | trace_event=[event-list] | |
3767 | [FTRACE] Set and start specified trace events in order | |
3768 | to facilitate early boot debugging. | |
3769 | See also Documentation/trace/events.txt | |
3770 | ||
3771 | trace_options=[option-list] | |
3772 | [FTRACE] Enable or disable tracer options at boot. | |
3773 | The option-list is a comma delimited list of options | |
3774 | that can be enabled or disabled just as if you were | |
3775 | to echo the option name into | |
3776 | ||
3777 | /sys/kernel/debug/tracing/trace_options | |
3778 | ||
3779 | For example, to enable stacktrace option (to dump the | |
3780 | stack trace of each event), add to the command line: | |
3781 | ||
3782 | trace_options=stacktrace | |
3783 | ||
3784 | See also Documentation/trace/ftrace.txt "trace options" | |
3785 | section. | |
3786 | ||
3787 | tp_printk[FTRACE] | |
3788 | Have the tracepoints sent to printk as well as the | |
3789 | tracing ring buffer. This is useful for early boot up | |
3790 | where the system hangs or reboots and does not give the | |
3791 | option for reading the tracing buffer or performing a | |
3792 | ftrace_dump_on_oops. | |
3793 | ||
3794 | To turn off having tracepoints sent to printk, | |
3795 | echo 0 > /proc/sys/kernel/tracepoint_printk | |
3796 | Note, echoing 1 into this file without the | |
3797 | tracepoint_printk kernel cmdline option has no effect. | |
3798 | ||
3799 | ** CAUTION ** | |
3800 | ||
3801 | Having tracepoints sent to printk() and activating high | |
3802 | frequency tracepoints such as irq or sched, can cause | |
3803 | the system to live lock. | |
3804 | ||
3805 | traceoff_on_warning | |
3806 | [FTRACE] enable this option to disable tracing when a | |
3807 | warning is hit. This turns off "tracing_on". Tracing can | |
3808 | be enabled again by echoing '1' into the "tracing_on" | |
3809 | file located in /sys/kernel/debug/tracing/ | |
3810 | ||
3811 | This option is useful, as it disables the trace before | |
3812 | the WARNING dump is called, which prevents the trace to | |
3813 | be filled with content caused by the warning output. | |
3814 | ||
3815 | This option can also be set at run time via the sysctl | |
3816 | option: kernel/traceoff_on_warning | |
3817 | ||
3818 | transparent_hugepage= | |
3819 | [KNL] | |
3820 | Format: [always|madvise|never] | |
3821 | Can be used to control the default behavior of the system | |
3822 | with respect to transparent hugepages. | |
3823 | See Documentation/vm/transhuge.txt for more details. | |
3824 | ||
3825 | tsc= Disable clocksource stability checks for TSC. | |
3826 | Format: <string> | |
3827 | [x86] reliable: mark tsc clocksource as reliable, this | |
3828 | disables clocksource verification at runtime, as well | |
3829 | as the stability checks done at bootup. Used to enable | |
3830 | high-resolution timer mode on older hardware, and in | |
3831 | virtualized environment. | |
3832 | [x86] noirqtime: Do not use TSC to do irq accounting. | |
3833 | Used to run time disable IRQ_TIME_ACCOUNTING on any | |
3834 | platforms where RDTSC is slow and this accounting | |
3835 | can add overhead. | |
3836 | ||
3837 | turbografx.map[2|3]= [HW,JOY] | |
3838 | TurboGraFX parallel port interface | |
3839 | Format: | |
3840 | <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> | |
3841 | See also Documentation/input/joystick-parport.txt | |
3842 | ||
3843 | udbg-immortal [PPC] When debugging early kernel crashes that | |
3844 | happen after console_init() and before a proper | |
3845 | console driver takes over, this boot options might | |
3846 | help "seeing" what's going on. | |
3847 | ||
3848 | uhash_entries= [KNL,NET] | |
3849 | Set number of hash buckets for UDP/UDP-Lite connections | |
3850 | ||
3851 | uhci-hcd.ignore_oc= | |
3852 | [USB] Ignore overcurrent events (default N). | |
3853 | Some badly-designed motherboards generate lots of | |
3854 | bogus events, for ports that aren't wired to | |
3855 | anything. Set this parameter to avoid log spamming. | |
3856 | Note that genuine overcurrent events won't be | |
3857 | reported either. | |
3858 | ||
3859 | unknown_nmi_panic | |
3860 | [X86] Cause panic on unknown NMI. | |
3861 | ||
3862 | usbcore.authorized_default= | |
3863 | [USB] Default USB device authorization: | |
3864 | (default -1 = authorized except for wireless USB, | |
3865 | 0 = not authorized, 1 = authorized) | |
3866 | ||
3867 | usbcore.autosuspend= | |
3868 | [USB] The autosuspend time delay (in seconds) used | |
3869 | for newly-detected USB devices (default 2). This | |
3870 | is the time required before an idle device will be | |
3871 | autosuspended. Devices for which the delay is set | |
3872 | to a negative value won't be autosuspended at all. | |
3873 | ||
3874 | usbcore.usbfs_snoop= | |
3875 | [USB] Set to log all usbfs traffic (default 0 = off). | |
3876 | ||
3877 | usbcore.usbfs_snoop_max= | |
3878 | [USB] Maximum number of bytes to snoop in each URB | |
3879 | (default = 65536). | |
3880 | ||
3881 | usbcore.blinkenlights= | |
3882 | [USB] Set to cycle leds on hubs (default 0 = off). | |
3883 | ||
3884 | usbcore.old_scheme_first= | |
3885 | [USB] Start with the old device initialization | |
3886 | scheme (default 0 = off). | |
3887 | ||
3888 | usbcore.usbfs_memory_mb= | |
3889 | [USB] Memory limit (in MB) for buffers allocated by | |
3890 | usbfs (default = 16, 0 = max = 2047). | |
3891 | ||
3892 | usbcore.use_both_schemes= | |
3893 | [USB] Try the other device initialization scheme | |
3894 | if the first one fails (default 1 = enabled). | |
3895 | ||
3896 | usbcore.initial_descriptor_timeout= | |
3897 | [USB] Specifies timeout for the initial 64-byte | |
3898 | USB_REQ_GET_DESCRIPTOR request in milliseconds | |
3899 | (default 5000 = 5.0 seconds). | |
3900 | ||
3901 | usbhid.mousepoll= | |
3902 | [USBHID] The interval which mice are to be polled at. | |
3903 | ||
3904 | usb-storage.delay_use= | |
3905 | [UMS] The delay in seconds before a new device is | |
3906 | scanned for Logical Units (default 1). | |
3907 | ||
3908 | usb-storage.quirks= | |
3909 | [UMS] A list of quirks entries to supplement or | |
3910 | override the built-in unusual_devs list. List | |
3911 | entries are separated by commas. Each entry has | |
3912 | the form VID:PID:Flags where VID and PID are Vendor | |
3913 | and Product ID values (4-digit hex numbers) and | |
3914 | Flags is a set of characters, each corresponding | |
3915 | to a common usb-storage quirk flag as follows: | |
3916 | a = SANE_SENSE (collect more than 18 bytes | |
3917 | of sense data); | |
3918 | b = BAD_SENSE (don't collect more than 18 | |
3919 | bytes of sense data); | |
3920 | c = FIX_CAPACITY (decrease the reported | |
3921 | device capacity by one sector); | |
3922 | d = NO_READ_DISC_INFO (don't use | |
3923 | READ_DISC_INFO command); | |
3924 | e = NO_READ_CAPACITY_16 (don't use | |
3925 | READ_CAPACITY_16 command); | |
3926 | f = NO_REPORT_OPCODES (don't use report opcodes | |
3927 | command, uas only); | |
3928 | g = MAX_SECTORS_240 (don't transfer more than | |
3929 | 240 sectors at a time, uas only); | |
3930 | h = CAPACITY_HEURISTICS (decrease the | |
3931 | reported device capacity by one | |
3932 | sector if the number is odd); | |
3933 | i = IGNORE_DEVICE (don't bind to this | |
3934 | device); | |
3935 | l = NOT_LOCKABLE (don't try to lock and | |
3936 | unlock ejectable media); | |
3937 | m = MAX_SECTORS_64 (don't transfer more | |
3938 | than 64 sectors = 32 KB at a time); | |
3939 | n = INITIAL_READ10 (force a retry of the | |
3940 | initial READ(10) command); | |
3941 | o = CAPACITY_OK (accept the capacity | |
3942 | reported by the device); | |
3943 | p = WRITE_CACHE (the device cache is ON | |
3944 | by default); | |
3945 | r = IGNORE_RESIDUE (the device reports | |
3946 | bogus residue values); | |
3947 | s = SINGLE_LUN (the device has only one | |
3948 | Logical Unit); | |
3949 | t = NO_ATA_1X (don't allow ATA(12) and ATA(16) | |
3950 | commands, uas only); | |
3951 | u = IGNORE_UAS (don't bind to the uas driver); | |
3952 | w = NO_WP_DETECT (don't test whether the | |
3953 | medium is write-protected). | |
3954 | Example: quirks=0419:aaf5:rl,0421:0433:rc | |
3955 | ||
3956 | user_debug= [KNL,ARM] | |
3957 | Format: <int> | |
3958 | See arch/arm/Kconfig.debug help text. | |
3959 | 1 - undefined instruction events | |
3960 | 2 - system calls | |
3961 | 4 - invalid data aborts | |
3962 | 8 - SIGSEGV faults | |
3963 | 16 - SIGBUS faults | |
3964 | Example: user_debug=31 | |
3965 | ||
3966 | userpte= | |
3967 | [X86] Flags controlling user PTE allocations. | |
3968 | ||
3969 | nohigh = do not allocate PTE pages in | |
3970 | HIGHMEM regardless of setting | |
3971 | of CONFIG_HIGHPTE. | |
3972 | ||
3973 | vdso= [X86,SH] | |
3974 | On X86_32, this is an alias for vdso32=. Otherwise: | |
3975 | ||
3976 | vdso=1: enable VDSO (the default) | |
3977 | vdso=0: disable VDSO mapping | |
3978 | ||
3979 | vdso32= [X86] Control the 32-bit vDSO | |
3980 | vdso32=1: enable 32-bit VDSO | |
3981 | vdso32=0 or vdso32=2: disable 32-bit VDSO | |
3982 | ||
3983 | See the help text for CONFIG_COMPAT_VDSO for more | |
3984 | details. If CONFIG_COMPAT_VDSO is set, the default is | |
3985 | vdso32=0; otherwise, the default is vdso32=1. | |
3986 | ||
3987 | For compatibility with older kernels, vdso32=2 is an | |
3988 | alias for vdso32=0. | |
3989 | ||
3990 | Try vdso32=0 if you encounter an error that says: | |
3991 | dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! | |
3992 | ||
3993 | vector= [IA-64,SMP] | |
3994 | vector=percpu: enable percpu vector domain | |
3995 | ||
3996 | video= [FB] Frame buffer configuration | |
3997 | See Documentation/fb/modedb.txt. | |
3998 | ||
3999 | video.brightness_switch_enabled= [0,1] | |
4000 | If set to 1, on receiving an ACPI notify event | |
4001 | generated by hotkey, video driver will adjust brightness | |
4002 | level and then send out the event to user space through | |
4003 | the allocated input device; If set to 0, video driver | |
4004 | will only send out the event without touching backlight | |
4005 | brightness level. | |
4006 | default: 1 | |
4007 | ||
4008 | virtio_mmio.device= | |
4009 | [VMMIO] Memory mapped virtio (platform) device. | |
4010 | ||
4011 | <size>@<baseaddr>:<irq>[:<id>] | |
4012 | where: | |
4013 | <size> := size (can use standard suffixes | |
4014 | like K, M and G) | |
4015 | <baseaddr> := physical base address | |
4016 | <irq> := interrupt number (as passed to | |
4017 | request_irq()) | |
4018 | <id> := (optional) platform device id | |
4019 | example: | |
4020 | virtio_mmio.device=1K@0x100b0000:48:7 | |
4021 | ||
4022 | Can be used multiple times for multiple devices. | |
4023 | ||
4024 | vga= [BOOT,X86-32] Select a particular video mode | |
4025 | See Documentation/x86/boot.txt and | |
4026 | Documentation/svga.txt. | |
4027 | Use vga=ask for menu. | |
4028 | This is actually a boot loader parameter; the value is | |
4029 | passed to the kernel using a special protocol. | |
4030 | ||
4031 | vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact | |
4032 | size of <nn>. This can be used to increase the | |
4033 | minimum size (128MB on x86). It can also be used to | |
4034 | decrease the size and leave more room for directly | |
4035 | mapped kernel RAM. | |
4036 | ||
4037 | vmhalt= [KNL,S390] Perform z/VM CP command after system halt. | |
4038 | Format: <command> | |
4039 | ||
4040 | vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. | |
4041 | Format: <command> | |
4042 | ||
4043 | vmpoff= [KNL,S390] Perform z/VM CP command after power off. | |
4044 | Format: <command> | |
4045 | ||
4046 | vsyscall= [X86-64] | |
4047 | Controls the behavior of vsyscalls (i.e. calls to | |
4048 | fixed addresses of 0xffffffffff600x00 from legacy | |
4049 | code). Most statically-linked binaries and older | |
4050 | versions of glibc use these calls. Because these | |
4051 | functions are at fixed addresses, they make nice | |
4052 | targets for exploits that can control RIP. | |
4053 | ||
4054 | emulate [default] Vsyscalls turn into traps and are | |
4055 | emulated reasonably safely. | |
4056 | ||
4057 | native Vsyscalls are native syscall instructions. | |
4058 | This is a little bit faster than trapping | |
4059 | and makes a few dynamic recompilers work | |
4060 | better than they would in emulation mode. | |
4061 | It also makes exploits much easier to write. | |
4062 | ||
4063 | none Vsyscalls don't work at all. This makes | |
4064 | them quite hard to use for exploits but | |
4065 | might break your system. | |
4066 | ||
4067 | vt.color= [VT] Default text color. | |
4068 | Format: 0xYX, X = foreground, Y = background. | |
4069 | Default: 0x07 = light gray on black. | |
4070 | ||
4071 | vt.cur_default= [VT] Default cursor shape. | |
4072 | Format: 0xCCBBAA, where AA, BB, and CC are the same as | |
4073 | the parameters of the <Esc>[?A;B;Cc escape sequence; | |
4074 | see VGA-softcursor.txt. Default: 2 = underline. | |
4075 | ||
4076 | vt.default_blu= [VT] | |
4077 | Format: <blue0>,<blue1>,<blue2>,...,<blue15> | |
4078 | Change the default blue palette of the console. | |
4079 | This is a 16-member array composed of values | |
4080 | ranging from 0-255. | |
4081 | ||
4082 | vt.default_grn= [VT] | |
4083 | Format: <green0>,<green1>,<green2>,...,<green15> | |
4084 | Change the default green palette of the console. | |
4085 | This is a 16-member array composed of values | |
4086 | ranging from 0-255. | |
4087 | ||
4088 | vt.default_red= [VT] | |
4089 | Format: <red0>,<red1>,<red2>,...,<red15> | |
4090 | Change the default red palette of the console. | |
4091 | This is a 16-member array composed of values | |
4092 | ranging from 0-255. | |
4093 | ||
4094 | vt.default_utf8= | |
4095 | [VT] | |
4096 | Format=<0|1> | |
4097 | Set system-wide default UTF-8 mode for all tty's. | |
4098 | Default is 1, i.e. UTF-8 mode is enabled for all | |
4099 | newly opened terminals. | |
4100 | ||
4101 | vt.global_cursor_default= | |
4102 | [VT] | |
4103 | Format=<-1|0|1> | |
4104 | Set system-wide default for whether a cursor | |
4105 | is shown on new VTs. Default is -1, | |
4106 | i.e. cursors will be created by default unless | |
4107 | overridden by individual drivers. 0 will hide | |
4108 | cursors, 1 will display them. | |
4109 | ||
4110 | vt.italic= [VT] Default color for italic text; 0-15. | |
4111 | Default: 2 = green. | |
4112 | ||
4113 | vt.underline= [VT] Default color for underlined text; 0-15. | |
4114 | Default: 3 = cyan. | |
4115 | ||
4116 | watchdog timers [HW,WDT] For information on watchdog timers, | |
4117 | see Documentation/watchdog/watchdog-parameters.txt | |
4118 | or other driver-specific files in the | |
4119 | Documentation/watchdog/ directory. | |
4120 | ||
4121 | workqueue.disable_numa | |
4122 | By default, all work items queued to unbound | |
4123 | workqueues are affine to the NUMA nodes they're | |
4124 | issued on, which results in better behavior in | |
4125 | general. If NUMA affinity needs to be disabled for | |
4126 | whatever reason, this option can be used. Note | |
4127 | that this also can be controlled per-workqueue for | |
4128 | workqueues visible under /sys/bus/workqueue/. | |
4129 | ||
4130 | workqueue.power_efficient | |
4131 | Per-cpu workqueues are generally preferred because | |
4132 | they show better performance thanks to cache | |
4133 | locality; unfortunately, per-cpu workqueues tend to | |
4134 | be more power hungry than unbound workqueues. | |
4135 | ||
4136 | Enabling this makes the per-cpu workqueues which | |
4137 | were observed to contribute significantly to power | |
4138 | consumption unbound, leading to measurably lower | |
4139 | power usage at the cost of small performance | |
4140 | overhead. | |
4141 | ||
4142 | The default value of this parameter is determined by | |
4143 | the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. | |
4144 | ||
4145 | x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of | |
4146 | default x2apic cluster mode on platforms | |
4147 | supporting x2apic. | |
4148 | ||
4149 | x86_intel_mid_timer= [X86-32,APBT] | |
4150 | Choose timer option for x86 Intel MID platform. | |
4151 | Two valid options are apbt timer only and lapic timer | |
4152 | plus one apbt timer for broadcast timer. | |
4153 | x86_intel_mid_timer=apbt_only | lapic_and_apbt | |
4154 | ||
4155 | xen_512gb_limit [KNL,X86-64,XEN] | |
4156 | Restricts the kernel running paravirtualized under Xen | |
4157 | to use only up to 512 GB of RAM. The reason to do so is | |
4158 | crash analysis tools and Xen tools for doing domain | |
4159 | save/restore/migration must be enabled to handle larger | |
4160 | domains. | |
4161 | ||
4162 | xen_emul_unplug= [HW,X86,XEN] | |
4163 | Unplug Xen emulated devices | |
4164 | Format: [unplug0,][unplug1] | |
4165 | ide-disks -- unplug primary master IDE devices | |
4166 | aux-ide-disks -- unplug non-primary-master IDE devices | |
4167 | nics -- unplug network devices | |
4168 | all -- unplug all emulated devices (NICs and IDE disks) | |
4169 | unnecessary -- unplugging emulated devices is | |
4170 | unnecessary even if the host did not respond to | |
4171 | the unplug protocol | |
4172 | never -- do not unplug even if version check succeeds | |
4173 | ||
4174 | xen_nopvspin [X86,XEN] | |
4175 | Disables the ticketlock slowpath using Xen PV | |
4176 | optimizations. | |
4177 | ||
4178 | xen_nopv [X86] | |
4179 | Disables the PV optimizations forcing the HVM guest to | |
4180 | run as generic HVM guest with no PV drivers. | |
4181 | ||
4182 | xirc2ps_cs= [NET,PCMCIA] | |
4183 | Format: | |
4184 | <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] | |
4185 | ||
4186 | ______________________________________________________________________ | |
4187 | ||
4188 | TODO: | |
4189 | ||
4190 | Add more DRM drivers. |