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Commit | Line | Data |
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1 | acpi= [HW,ACPI,X86,ARM64] | |
2 | Advanced Configuration and Power Interface | |
3 | Format: { force | on | off | strict | noirq | rsdt | | |
4 | copy_dsdt } | |
5 | force -- enable ACPI if default was off | |
6 | on -- enable ACPI but allow fallback to DT [arm64] | |
7 | off -- disable ACPI if default was on | |
8 | noirq -- do not use ACPI for IRQ routing | |
9 | strict -- Be less tolerant of platforms that are not | |
10 | strictly ACPI specification compliant. | |
11 | rsdt -- prefer RSDT over (default) XSDT | |
12 | copy_dsdt -- copy DSDT to memory | |
13 | For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force" | |
14 | are available | |
15 | ||
16 | See also Documentation/power/runtime_pm.txt, pci=noacpi | |
17 | ||
18 | acpi_apic_instance= [ACPI, IOAPIC] | |
19 | Format: <int> | |
20 | 2: use 2nd APIC table, if available | |
21 | 1,0: use 1st APIC table | |
22 | default: 0 | |
23 | ||
24 | acpi_backlight= [HW,ACPI] | |
25 | acpi_backlight=vendor | |
26 | acpi_backlight=video | |
27 | If set to vendor, prefer vendor specific driver | |
28 | (e.g. thinkpad_acpi, sony_acpi, etc.) instead | |
29 | of the ACPI video.ko driver. | |
30 | ||
31 | acpi_force_32bit_fadt_addr | |
32 | force FADT to use 32 bit addresses rather than the | |
33 | 64 bit X_* addresses. Some firmware have broken 64 | |
34 | bit addresses for force ACPI ignore these and use | |
35 | the older legacy 32 bit addresses. | |
36 | ||
37 | acpica_no_return_repair [HW, ACPI] | |
38 | Disable AML predefined validation mechanism | |
39 | This mechanism can repair the evaluation result to make | |
40 | the return objects more ACPI specification compliant. | |
41 | This option is useful for developers to identify the | |
42 | root cause of an AML interpreter issue when the issue | |
43 | has something to do with the repair mechanism. | |
44 | ||
45 | acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] | |
46 | acpi.debug_level= [HW,ACPI,ACPI_DEBUG] | |
47 | Format: <int> | |
48 | CONFIG_ACPI_DEBUG must be enabled to produce any ACPI | |
49 | debug output. Bits in debug_layer correspond to a | |
50 | _COMPONENT in an ACPI source file, e.g., | |
51 | #define _COMPONENT ACPI_PCI_COMPONENT | |
52 | Bits in debug_level correspond to a level in | |
53 | ACPI_DEBUG_PRINT statements, e.g., | |
54 | ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... | |
55 | The debug_level mask defaults to "info". See | |
56 | Documentation/acpi/debug.txt for more information about | |
57 | debug layers and levels. | |
58 | ||
59 | Enable processor driver info messages: | |
60 | acpi.debug_layer=0x20000000 | |
61 | Enable PCI/PCI interrupt routing info messages: | |
62 | acpi.debug_layer=0x400000 | |
63 | Enable AML "Debug" output, i.e., stores to the Debug | |
64 | object while interpreting AML: | |
65 | acpi.debug_layer=0xffffffff acpi.debug_level=0x2 | |
66 | Enable all messages related to ACPI hardware: | |
67 | acpi.debug_layer=0x2 acpi.debug_level=0xffffffff | |
68 | ||
69 | Some values produce so much output that the system is | |
70 | unusable. The "log_buf_len" parameter may be useful | |
71 | if you need to capture more output. | |
72 | ||
73 | acpi_enforce_resources= [ACPI] | |
74 | { strict | lax | no } | |
75 | Check for resource conflicts between native drivers | |
76 | and ACPI OperationRegions (SystemIO and SystemMemory | |
77 | only). IO ports and memory declared in ACPI might be | |
78 | used by the ACPI subsystem in arbitrary AML code and | |
79 | can interfere with legacy drivers. | |
80 | strict (default): access to resources claimed by ACPI | |
81 | is denied; legacy drivers trying to access reserved | |
82 | resources will fail to bind to device using them. | |
83 | lax: access to resources claimed by ACPI is allowed; | |
84 | legacy drivers trying to access reserved resources | |
85 | will bind successfully but a warning message is logged. | |
86 | no: ACPI OperationRegions are not marked as reserved, | |
87 | no further checks are performed. | |
88 | ||
89 | acpi_force_table_verification [HW,ACPI] | |
90 | Enable table checksum verification during early stage. | |
91 | By default, this is disabled due to x86 early mapping | |
92 | size limitation. | |
93 | ||
94 | acpi_irq_balance [HW,ACPI] | |
95 | ACPI will balance active IRQs | |
96 | default in APIC mode | |
97 | ||
98 | acpi_irq_nobalance [HW,ACPI] | |
99 | ACPI will not move active IRQs (default) | |
100 | default in PIC mode | |
101 | ||
102 | acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA | |
103 | Format: <irq>,<irq>... | |
104 | ||
105 | acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for | |
106 | use by PCI | |
107 | Format: <irq>,<irq>... | |
108 | ||
109 | acpi_mask_gpe= [HW,ACPI] | |
110 | Due to the existence of _Lxx/_Exx, some GPEs triggered | |
111 | by unsupported hardware/firmware features can result in | |
112 | GPE floodings that cannot be automatically disabled by | |
113 | the GPE dispatcher. | |
114 | This facility can be used to prevent such uncontrolled | |
115 | GPE floodings. | |
116 | Format: <int> | |
117 | ||
118 | acpi_no_auto_serialize [HW,ACPI] | |
119 | Disable auto-serialization of AML methods | |
120 | AML control methods that contain the opcodes to create | |
121 | named objects will be marked as "Serialized" by the | |
122 | auto-serialization feature. | |
123 | This feature is enabled by default. | |
124 | This option allows to turn off the feature. | |
125 | ||
126 | acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump | |
127 | kernels. | |
128 | ||
129 | acpi_no_static_ssdt [HW,ACPI] | |
130 | Disable installation of static SSDTs at early boot time | |
131 | By default, SSDTs contained in the RSDT/XSDT will be | |
132 | installed automatically and they will appear under | |
133 | /sys/firmware/acpi/tables. | |
134 | This option turns off this feature. | |
135 | Note that specifying this option does not affect | |
136 | dynamic table installation which will install SSDT | |
137 | tables to /sys/firmware/acpi/tables/dynamic. | |
138 | ||
139 | acpi_rsdp= [ACPI,EFI,KEXEC] | |
140 | Pass the RSDP address to the kernel, mostly used | |
141 | on machines running EFI runtime service to boot the | |
142 | second kernel for kdump. | |
143 | ||
144 | acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS | |
145 | Format: To spoof as Windows 98: ="Microsoft Windows" | |
146 | ||
147 | acpi_rev_override [ACPI] Override the _REV object to return 5 (instead | |
148 | of 2 which is mandated by ACPI 6) as the supported ACPI | |
149 | specification revision (when using this switch, it may | |
150 | be necessary to carry out a cold reboot _twice_ in a | |
151 | row to make it take effect on the platform firmware). | |
152 | ||
153 | acpi_osi= [HW,ACPI] Modify list of supported OS interface strings | |
154 | acpi_osi="string1" # add string1 | |
155 | acpi_osi="!string2" # remove string2 | |
156 | acpi_osi=!* # remove all strings | |
157 | acpi_osi=! # disable all built-in OS vendor | |
158 | strings | |
159 | acpi_osi=!! # enable all built-in OS vendor | |
160 | strings | |
161 | acpi_osi= # disable all strings | |
162 | ||
163 | 'acpi_osi=!' can be used in combination with single or | |
164 | multiple 'acpi_osi="string1"' to support specific OS | |
165 | vendor string(s). Note that such command can only | |
166 | affect the default state of the OS vendor strings, thus | |
167 | it cannot affect the default state of the feature group | |
168 | strings and the current state of the OS vendor strings, | |
169 | specifying it multiple times through kernel command line | |
170 | is meaningless. This command is useful when one do not | |
171 | care about the state of the feature group strings which | |
172 | should be controlled by the OSPM. | |
173 | Examples: | |
174 | 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent | |
175 | to 'acpi_osi="Windows 2000" acpi_osi=!', they all | |
176 | can make '_OSI("Windows 2000")' TRUE. | |
177 | ||
178 | 'acpi_osi=' cannot be used in combination with other | |
179 | 'acpi_osi=' command lines, the _OSI method will not | |
180 | exist in the ACPI namespace. NOTE that such command can | |
181 | only affect the _OSI support state, thus specifying it | |
182 | multiple times through kernel command line is also | |
183 | meaningless. | |
184 | Examples: | |
185 | 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' | |
186 | FALSE. | |
187 | ||
188 | 'acpi_osi=!*' can be used in combination with single or | |
189 | multiple 'acpi_osi="string1"' to support specific | |
190 | string(s). Note that such command can affect the | |
191 | current state of both the OS vendor strings and the | |
192 | feature group strings, thus specifying it multiple times | |
193 | through kernel command line is meaningful. But it may | |
194 | still not able to affect the final state of a string if | |
195 | there are quirks related to this string. This command | |
196 | is useful when one want to control the state of the | |
197 | feature group strings to debug BIOS issues related to | |
198 | the OSPM features. | |
199 | Examples: | |
200 | 1. 'acpi_osi="Module Device" acpi_osi=!*' can make | |
201 | '_OSI("Module Device")' FALSE. | |
202 | 2. 'acpi_osi=!* acpi_osi="Module Device"' can make | |
203 | '_OSI("Module Device")' TRUE. | |
204 | 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is | |
205 | equivalent to | |
206 | 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' | |
207 | and | |
208 | 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', | |
209 | they all will make '_OSI("Windows 2000")' TRUE. | |
210 | ||
211 | acpi_pm_good [X86] | |
212 | Override the pmtimer bug detection: force the kernel | |
213 | to assume that this machine's pmtimer latches its value | |
214 | and always returns good values. | |
215 | ||
216 | acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode | |
217 | Format: { level | edge | high | low } | |
218 | ||
219 | acpi_skip_timer_override [HW,ACPI] | |
220 | Recognize and ignore IRQ0/pin2 Interrupt Override. | |
221 | For broken nForce2 BIOS resulting in XT-PIC timer. | |
222 | ||
223 | acpi_sleep= [HW,ACPI] Sleep options | |
224 | Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, | |
225 | old_ordering, nonvs, sci_force_enable, nobl } | |
226 | See Documentation/power/video.txt for information on | |
227 | s3_bios and s3_mode. | |
228 | s3_beep is for debugging; it makes the PC's speaker beep | |
229 | as soon as the kernel's real-mode entry point is called. | |
230 | s4_nohwsig prevents ACPI hardware signature from being | |
231 | used during resume from hibernation. | |
232 | old_ordering causes the ACPI 1.0 ordering of the _PTS | |
233 | control method, with respect to putting devices into | |
234 | low power states, to be enforced (the ACPI 2.0 ordering | |
235 | of _PTS is used by default). | |
236 | nonvs prevents the kernel from saving/restoring the | |
237 | ACPI NVS memory during suspend/hibernation and resume. | |
238 | sci_force_enable causes the kernel to set SCI_EN directly | |
239 | on resume from S1/S3 (which is against the ACPI spec, | |
240 | but some broken systems don't work without it). | |
241 | nobl causes the internal blacklist of systems known to | |
242 | behave incorrectly in some ways with respect to system | |
243 | suspend and resume to be ignored (use wisely). | |
244 | ||
245 | acpi_use_timer_override [HW,ACPI] | |
246 | Use timer override. For some broken Nvidia NF5 boards | |
247 | that require a timer override, but don't have HPET | |
248 | ||
249 | add_efi_memmap [EFI; X86] Include EFI memory map in | |
250 | kernel's map of available physical RAM. | |
251 | ||
252 | agp= [AGP] | |
253 | { off | try_unsupported } | |
254 | off: disable AGP support | |
255 | try_unsupported: try to drive unsupported chipsets | |
256 | (may crash computer or cause data corruption) | |
257 | ||
258 | ALSA [HW,ALSA] | |
259 | See Documentation/sound/alsa-configuration.rst | |
260 | ||
261 | alignment= [KNL,ARM] | |
262 | Allow the default userspace alignment fault handler | |
263 | behaviour to be specified. Bit 0 enables warnings, | |
264 | bit 1 enables fixups, and bit 2 sends a segfault. | |
265 | ||
266 | align_va_addr= [X86-64] | |
267 | Align virtual addresses by clearing slice [14:12] when | |
268 | allocating a VMA at process creation time. This option | |
269 | gives you up to 3% performance improvement on AMD F15h | |
270 | machines (where it is enabled by default) for a | |
271 | CPU-intensive style benchmark, and it can vary highly in | |
272 | a microbenchmark depending on workload and compiler. | |
273 | ||
274 | 32: only for 32-bit processes | |
275 | 64: only for 64-bit processes | |
276 | on: enable for both 32- and 64-bit processes | |
277 | off: disable for both 32- and 64-bit processes | |
278 | ||
279 | alloc_snapshot [FTRACE] | |
280 | Allocate the ftrace snapshot buffer on boot up when the | |
281 | main buffer is allocated. This is handy if debugging | |
282 | and you need to use tracing_snapshot() on boot up, and | |
283 | do not want to use tracing_snapshot_alloc() as it needs | |
284 | to be done where GFP_KERNEL allocations are allowed. | |
285 | ||
286 | amd_iommu= [HW,X86-64] | |
287 | Pass parameters to the AMD IOMMU driver in the system. | |
288 | Possible values are: | |
289 | fullflush - enable flushing of IO/TLB entries when | |
290 | they are unmapped. Otherwise they are | |
291 | flushed before they will be reused, which | |
292 | is a lot of faster | |
293 | off - do not initialize any AMD IOMMU found in | |
294 | the system | |
295 | force_isolation - Force device isolation for all | |
296 | devices. The IOMMU driver is not | |
297 | allowed anymore to lift isolation | |
298 | requirements as needed. This option | |
299 | does not override iommu=pt | |
300 | ||
301 | amd_iommu_dump= [HW,X86-64] | |
302 | Enable AMD IOMMU driver option to dump the ACPI table | |
303 | for AMD IOMMU. With this option enabled, AMD IOMMU | |
304 | driver will print ACPI tables for AMD IOMMU during | |
305 | IOMMU initialization. | |
306 | ||
307 | amd_iommu_intr= [HW,X86-64] | |
308 | Specifies one of the following AMD IOMMU interrupt | |
309 | remapping modes: | |
310 | legacy - Use legacy interrupt remapping mode. | |
311 | vapic - Use virtual APIC mode, which allows IOMMU | |
312 | to inject interrupts directly into guest. | |
313 | This mode requires kvm-amd.avic=1. | |
314 | (Default when IOMMU HW support is present.) | |
315 | ||
316 | amijoy.map= [HW,JOY] Amiga joystick support | |
317 | Map of devices attached to JOY0DAT and JOY1DAT | |
318 | Format: <a>,<b> | |
319 | See also Documentation/input/joydev/joystick.rst | |
320 | ||
321 | analog.map= [HW,JOY] Analog joystick and gamepad support | |
322 | Specifies type or capabilities of an analog joystick | |
323 | connected to one of 16 gameports | |
324 | Format: <type1>,<type2>,..<type16> | |
325 | ||
326 | apc= [HW,SPARC] | |
327 | Power management functions (SPARCstation-4/5 + deriv.) | |
328 | Format: noidle | |
329 | Disable APC CPU standby support. SPARCstation-Fox does | |
330 | not play well with APC CPU idle - disable it if you have | |
331 | APC and your system crashes randomly. | |
332 | ||
333 | apic= [APIC,X86] Advanced Programmable Interrupt Controller | |
334 | Change the output verbosity whilst booting | |
335 | Format: { quiet (default) | verbose | debug } | |
336 | Change the amount of debugging information output | |
337 | when initialising the APIC and IO-APIC components. | |
338 | For X86-32, this can also be used to specify an APIC | |
339 | driver name. | |
340 | Format: apic=driver_name | |
341 | Examples: apic=bigsmp | |
342 | ||
343 | apic_extnmi= [APIC,X86] External NMI delivery setting | |
344 | Format: { bsp (default) | all | none } | |
345 | bsp: External NMI is delivered only to CPU 0 | |
346 | all: External NMIs are broadcast to all CPUs as a | |
347 | backup of CPU 0 | |
348 | none: External NMI is masked for all CPUs. This is | |
349 | useful so that a dump capture kernel won't be | |
350 | shot down by NMI | |
351 | ||
352 | autoconf= [IPV6] | |
353 | See Documentation/networking/ipv6.txt. | |
354 | ||
355 | show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller | |
356 | Limit apic dumping. The parameter defines the maximal | |
357 | number of local apics being dumped. Also it is possible | |
358 | to set it to "all" by meaning -- no limit here. | |
359 | Format: { 1 (default) | 2 | ... | all }. | |
360 | The parameter valid if only apic=debug or | |
361 | apic=verbose is specified. | |
362 | Example: apic=debug show_lapic=all | |
363 | ||
364 | apm= [APM] Advanced Power Management | |
365 | See header of arch/x86/kernel/apm_32.c. | |
366 | ||
367 | arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards | |
368 | Format: <io>,<irq>,<nodeID> | |
369 | ||
370 | ataflop= [HW,M68k] | |
371 | ||
372 | atarimouse= [HW,MOUSE] Atari Mouse | |
373 | ||
374 | atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, | |
375 | EzKey and similar keyboards | |
376 | ||
377 | atkbd.reset= [HW] Reset keyboard during initialization | |
378 | ||
379 | atkbd.set= [HW] Select keyboard code set | |
380 | Format: <int> (2 = AT (default), 3 = PS/2) | |
381 | ||
382 | atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar | |
383 | keyboards | |
384 | ||
385 | atkbd.softraw= [HW] Choose between synthetic and real raw mode | |
386 | Format: <bool> (0 = real, 1 = synthetic (default)) | |
387 | ||
388 | atkbd.softrepeat= [HW] | |
389 | Use software keyboard repeat | |
390 | ||
391 | audit= [KNL] Enable the audit sub-system | |
392 | Format: { "0" | "1" | "off" | "on" } | |
393 | 0 | off - kernel audit is disabled and can not be | |
394 | enabled until the next reboot | |
395 | unset - kernel audit is initialized but disabled and | |
396 | will be fully enabled by the userspace auditd. | |
397 | 1 | on - kernel audit is initialized and partially | |
398 | enabled, storing at most audit_backlog_limit | |
399 | messages in RAM until it is fully enabled by the | |
400 | userspace auditd. | |
401 | Default: unset | |
402 | ||
403 | audit_backlog_limit= [KNL] Set the audit queue size limit. | |
404 | Format: <int> (must be >=0) | |
405 | Default: 64 | |
406 | ||
407 | bau= [X86_UV] Enable the BAU on SGI UV. The default | |
408 | behavior is to disable the BAU (i.e. bau=0). | |
409 | Format: { "0" | "1" } | |
410 | 0 - Disable the BAU. | |
411 | 1 - Enable the BAU. | |
412 | unset - Disable the BAU. | |
413 | ||
414 | baycom_epp= [HW,AX25] | |
415 | Format: <io>,<mode> | |
416 | ||
417 | baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem | |
418 | Format: <io>,<mode> | |
419 | See header of drivers/net/hamradio/baycom_par.c. | |
420 | ||
421 | baycom_ser_fdx= [HW,AX25] | |
422 | BayCom Serial Port AX.25 Modem (Full Duplex Mode) | |
423 | Format: <io>,<irq>,<mode>[,<baud>] | |
424 | See header of drivers/net/hamradio/baycom_ser_fdx.c. | |
425 | ||
426 | baycom_ser_hdx= [HW,AX25] | |
427 | BayCom Serial Port AX.25 Modem (Half Duplex Mode) | |
428 | Format: <io>,<irq>,<mode> | |
429 | See header of drivers/net/hamradio/baycom_ser_hdx.c. | |
430 | ||
431 | blkdevparts= Manual partition parsing of block device(s) for | |
432 | embedded devices based on command line input. | |
433 | See Documentation/block/cmdline-partition.txt | |
434 | ||
435 | boot_delay= Milliseconds to delay each printk during boot. | |
436 | Values larger than 10 seconds (10000) are changed to | |
437 | no delay (0). | |
438 | Format: integer | |
439 | ||
440 | bootmem_debug [KNL] Enable bootmem allocator debug messages. | |
441 | ||
442 | bert_disable [ACPI] | |
443 | Disable BERT OS support on buggy BIOSes. | |
444 | ||
445 | bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) | |
446 | bttv.radio= Most important insmod options are available as | |
447 | kernel args too. | |
448 | bttv.pll= See Documentation/media/v4l-drivers/bttv.rst | |
449 | bttv.tuner= | |
450 | ||
451 | bulk_remove=off [PPC] This parameter disables the use of the pSeries | |
452 | firmware feature for flushing multiple hpte entries | |
453 | at a time. | |
454 | ||
455 | c101= [NET] Moxa C101 synchronous serial card | |
456 | ||
457 | cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. | |
458 | Sometimes CPU hardware bugs make them report the cache | |
459 | size incorrectly. The kernel will attempt work arounds | |
460 | to fix known problems, but for some CPUs it is not | |
461 | possible to determine what the correct size should be. | |
462 | This option provides an override for these situations. | |
463 | ||
464 | ca_keys= [KEYS] This parameter identifies a specific key(s) on | |
465 | the system trusted keyring to be used for certificate | |
466 | trust validation. | |
467 | format: { id:<keyid> | builtin } | |
468 | ||
469 | cca= [MIPS] Override the kernel pages' cache coherency | |
470 | algorithm. Accepted values range from 0 to 7 | |
471 | inclusive. See arch/mips/include/asm/pgtable-bits.h | |
472 | for platform specific values (SB1, Loongson3 and | |
473 | others). | |
474 | ||
475 | ccw_timeout_log [S390] | |
476 | See Documentation/s390/CommonIO for details. | |
477 | ||
478 | cgroup_disable= [KNL] Disable a particular controller | |
479 | Format: {name of the controller(s) to disable} | |
480 | The effects of cgroup_disable=foo are: | |
481 | - foo isn't auto-mounted if you mount all cgroups in | |
482 | a single hierarchy | |
483 | - foo isn't visible as an individually mountable | |
484 | subsystem | |
485 | {Currently only "memory" controller deal with this and | |
486 | cut the overhead, others just disable the usage. So | |
487 | only cgroup_disable=memory is actually worthy} | |
488 | ||
489 | cgroup_no_v1= [KNL] Disable one, multiple, all cgroup controllers in v1 | |
490 | Format: { controller[,controller...] | "all" } | |
491 | Like cgroup_disable, but only applies to cgroup v1; | |
492 | the blacklisted controllers remain available in cgroup2. | |
493 | ||
494 | cgroup.memory= [KNL] Pass options to the cgroup memory controller. | |
495 | Format: <string> | |
496 | nosocket -- Disable socket memory accounting. | |
497 | nokmem -- Disable kernel memory accounting. | |
498 | ||
499 | checkreqprot [SELINUX] Set initial checkreqprot flag value. | |
500 | Format: { "0" | "1" } | |
501 | See security/selinux/Kconfig help text. | |
502 | 0 -- check protection applied by kernel (includes | |
503 | any implied execute protection). | |
504 | 1 -- check protection requested by application. | |
505 | Default value is set via a kernel config option. | |
506 | Value can be changed at runtime via | |
507 | /selinux/checkreqprot. | |
508 | ||
509 | cio_ignore= [S390] | |
510 | See Documentation/s390/CommonIO for details. | |
511 | clk_ignore_unused | |
512 | [CLK] | |
513 | Prevents the clock framework from automatically gating | |
514 | clocks that have not been explicitly enabled by a Linux | |
515 | device driver but are enabled in hardware at reset or | |
516 | by the bootloader/firmware. Note that this does not | |
517 | force such clocks to be always-on nor does it reserve | |
518 | those clocks in any way. This parameter is useful for | |
519 | debug and development, but should not be needed on a | |
520 | platform with proper driver support. For more | |
521 | information, see Documentation/driver-api/clk.rst. | |
522 | ||
523 | clock= [BUGS=X86-32, HW] gettimeofday clocksource override. | |
524 | [Deprecated] | |
525 | Forces specified clocksource (if available) to be used | |
526 | when calculating gettimeofday(). If specified | |
527 | clocksource is not available, it defaults to PIT. | |
528 | Format: { pit | tsc | cyclone | pmtmr } | |
529 | ||
530 | clocksource= Override the default clocksource | |
531 | Format: <string> | |
532 | Override the default clocksource and use the clocksource | |
533 | with the name specified. | |
534 | Some clocksource names to choose from, depending on | |
535 | the platform: | |
536 | [all] jiffies (this is the base, fallback clocksource) | |
537 | [ACPI] acpi_pm | |
538 | [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, | |
539 | pxa_timer,timer3,32k_counter,timer0_1 | |
540 | [X86-32] pit,hpet,tsc; | |
541 | scx200_hrt on Geode; cyclone on IBM x440 | |
542 | [MIPS] MIPS | |
543 | [PARISC] cr16 | |
544 | [S390] tod | |
545 | [SH] SuperH | |
546 | [SPARC64] tick | |
547 | [X86-64] hpet,tsc | |
548 | ||
549 | clocksource.arm_arch_timer.evtstrm= | |
550 | [ARM,ARM64] | |
551 | Format: <bool> | |
552 | Enable/disable the eventstream feature of the ARM | |
553 | architected timer so that code using WFE-based polling | |
554 | loops can be debugged more effectively on production | |
555 | systems. | |
556 | ||
557 | clearcpuid=BITNUM [X86] | |
558 | Disable CPUID feature X for the kernel. See | |
559 | arch/x86/include/asm/cpufeatures.h for the valid bit | |
560 | numbers. Note the Linux specific bits are not necessarily | |
561 | stable over kernel options, but the vendor specific | |
562 | ones should be. | |
563 | Also note that user programs calling CPUID directly | |
564 | or using the feature without checking anything | |
565 | will still see it. This just prevents it from | |
566 | being used by the kernel or shown in /proc/cpuinfo. | |
567 | Also note the kernel might malfunction if you disable | |
568 | some critical bits. | |
569 | ||
570 | cma=nn[MG]@[start[MG][-end[MG]]] | |
571 | [ARM,X86,KNL] | |
572 | Sets the size of kernel global memory area for | |
573 | contiguous memory allocations and optionally the | |
574 | placement constraint by the physical address range of | |
575 | memory allocations. A value of 0 disables CMA | |
576 | altogether. For more information, see | |
577 | include/linux/dma-contiguous.h | |
578 | ||
579 | cmo_free_hint= [PPC] Format: { yes | no } | |
580 | Specify whether pages are marked as being inactive | |
581 | when they are freed. This is used in CMO environments | |
582 | to determine OS memory pressure for page stealing by | |
583 | a hypervisor. | |
584 | Default: yes | |
585 | ||
586 | coherent_pool=nn[KMG] [ARM,KNL] | |
587 | Sets the size of memory pool for coherent, atomic dma | |
588 | allocations, by default set to 256K. | |
589 | ||
590 | com20020= [HW,NET] ARCnet - COM20020 chipset | |
591 | Format: | |
592 | <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] | |
593 | ||
594 | com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) | |
595 | Format: <io>[,<irq>] | |
596 | ||
597 | com90xx= [HW,NET] | |
598 | ARCnet - COM90xx chipset (memory-mapped buffers) | |
599 | Format: <io>[,<irq>[,<memstart>]] | |
600 | ||
601 | condev= [HW,S390] console device | |
602 | conmode= | |
603 | ||
604 | console= [KNL] Output console device and options. | |
605 | ||
606 | tty<n> Use the virtual console device <n>. | |
607 | ||
608 | ttyS<n>[,options] | |
609 | ttyUSB0[,options] | |
610 | Use the specified serial port. The options are of | |
611 | the form "bbbbpnf", where "bbbb" is the baud rate, | |
612 | "p" is parity ("n", "o", or "e"), "n" is number of | |
613 | bits, and "f" is flow control ("r" for RTS or | |
614 | omit it). Default is "9600n8". | |
615 | ||
616 | See Documentation/admin-guide/serial-console.rst for more | |
617 | information. See | |
618 | Documentation/networking/netconsole.txt for an | |
619 | alternative. | |
620 | ||
621 | uart[8250],io,<addr>[,options] | |
622 | uart[8250],mmio,<addr>[,options] | |
623 | uart[8250],mmio16,<addr>[,options] | |
624 | uart[8250],mmio32,<addr>[,options] | |
625 | uart[8250],0x<addr>[,options] | |
626 | Start an early, polled-mode console on the 8250/16550 | |
627 | UART at the specified I/O port or MMIO address, | |
628 | switching to the matching ttyS device later. | |
629 | MMIO inter-register address stride is either 8-bit | |
630 | (mmio), 16-bit (mmio16), or 32-bit (mmio32). | |
631 | If none of [io|mmio|mmio16|mmio32], <addr> is assumed | |
632 | to be equivalent to 'mmio'. 'options' are specified in | |
633 | the same format described for ttyS above; if unspecified, | |
634 | the h/w is not re-initialized. | |
635 | ||
636 | hvc<n> Use the hypervisor console device <n>. This is for | |
637 | both Xen and PowerPC hypervisors. | |
638 | ||
639 | If the device connected to the port is not a TTY but a braille | |
640 | device, prepend "brl," before the device type, for instance | |
641 | console=brl,ttyS0 | |
642 | For now, only VisioBraille is supported. | |
643 | ||
644 | console_msg_format= | |
645 | [KNL] Change console messages format | |
646 | default | |
647 | By default we print messages on consoles in | |
648 | "[time stamp] text\n" format (time stamp may not be | |
649 | printed, depending on CONFIG_PRINTK_TIME or | |
650 | `printk_time' param). | |
651 | syslog | |
652 | Switch to syslog format: "<%u>[time stamp] text\n" | |
653 | IOW, each message will have a facility and loglevel | |
654 | prefix. The format is similar to one used by syslog() | |
655 | syscall, or to executing "dmesg -S --raw" or to reading | |
656 | from /proc/kmsg. | |
657 | ||
658 | consoleblank= [KNL] The console blank (screen saver) timeout in | |
659 | seconds. A value of 0 disables the blank timer. | |
660 | Defaults to 0. | |
661 | ||
662 | coredump_filter= | |
663 | [KNL] Change the default value for | |
664 | /proc/<pid>/coredump_filter. | |
665 | See also Documentation/filesystems/proc.txt. | |
666 | ||
667 | coresight_cpu_debug.enable | |
668 | [ARM,ARM64] | |
669 | Format: <bool> | |
670 | Enable/disable the CPU sampling based debugging. | |
671 | 0: default value, disable debugging | |
672 | 1: enable debugging at boot time | |
673 | ||
674 | cpuidle.off=1 [CPU_IDLE] | |
675 | disable the cpuidle sub-system | |
676 | ||
677 | cpufreq.off=1 [CPU_FREQ] | |
678 | disable the cpufreq sub-system | |
679 | ||
680 | cpu_init_udelay=N | |
681 | [X86] Delay for N microsec between assert and de-assert | |
682 | of APIC INIT to start processors. This delay occurs | |
683 | on every CPU online, such as boot, and resume from suspend. | |
684 | Default: 10000 | |
685 | ||
686 | cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver | |
687 | Format: | |
688 | <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] | |
689 | ||
690 | crashkernel=size[KMG][@offset[KMG]] | |
691 | [KNL] Using kexec, Linux can switch to a 'crash kernel' | |
692 | upon panic. This parameter reserves the physical | |
693 | memory region [offset, offset + size] for that kernel | |
694 | image. If '@offset' is omitted, then a suitable offset | |
695 | is selected automatically. Check | |
696 | Documentation/kdump/kdump.txt for further details. | |
697 | ||
698 | crashkernel=range1:size1[,range2:size2,...][@offset] | |
699 | [KNL] Same as above, but depends on the memory | |
700 | in the running system. The syntax of range is | |
701 | start-[end] where start and end are both | |
702 | a memory unit (amount[KMG]). See also | |
703 | Documentation/kdump/kdump.txt for an example. | |
704 | ||
705 | crashkernel=size[KMG],high | |
706 | [KNL, x86_64] range could be above 4G. Allow kernel | |
707 | to allocate physical memory region from top, so could | |
708 | be above 4G if system have more than 4G ram installed. | |
709 | Otherwise memory region will be allocated below 4G, if | |
710 | available. | |
711 | It will be ignored if crashkernel=X is specified. | |
712 | crashkernel=size[KMG],low | |
713 | [KNL, x86_64] range under 4G. When crashkernel=X,high | |
714 | is passed, kernel could allocate physical memory region | |
715 | above 4G, that cause second kernel crash on system | |
716 | that require some amount of low memory, e.g. swiotlb | |
717 | requires at least 64M+32K low memory, also enough extra | |
718 | low memory is needed to make sure DMA buffers for 32-bit | |
719 | devices won't run out. Kernel would try to allocate at | |
720 | at least 256M below 4G automatically. | |
721 | This one let user to specify own low range under 4G | |
722 | for second kernel instead. | |
723 | 0: to disable low allocation. | |
724 | It will be ignored when crashkernel=X,high is not used | |
725 | or memory reserved is below 4G. | |
726 | ||
727 | cryptomgr.notests | |
728 | [KNL] Disable crypto self-tests | |
729 | ||
730 | cs89x0_dma= [HW,NET] | |
731 | Format: <dma> | |
732 | ||
733 | cs89x0_media= [HW,NET] | |
734 | Format: { rj45 | aui | bnc } | |
735 | ||
736 | dasd= [HW,NET] | |
737 | See header of drivers/s390/block/dasd_devmap.c. | |
738 | ||
739 | db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port | |
740 | (one device per port) | |
741 | Format: <port#>,<type> | |
742 | See also Documentation/input/devices/joystick-parport.rst | |
743 | ||
744 | ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot | |
745 | time. See | |
746 | Documentation/admin-guide/dynamic-debug-howto.rst for | |
747 | details. Deprecated, see dyndbg. | |
748 | ||
749 | debug [KNL] Enable kernel debugging (events log level). | |
750 | ||
751 | debug_locks_verbose= | |
752 | [KNL] verbose self-tests | |
753 | Format=<0|1> | |
754 | Print debugging info while doing the locking API | |
755 | self-tests. | |
756 | We default to 0 (no extra messages), setting it to | |
757 | 1 will print _a lot_ more information - normally | |
758 | only useful to kernel developers. | |
759 | ||
760 | debug_objects [KNL] Enable object debugging | |
761 | ||
762 | no_debug_objects | |
763 | [KNL] Disable object debugging | |
764 | ||
765 | debug_guardpage_minorder= | |
766 | [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this | |
767 | parameter allows control of the order of pages that will | |
768 | be intentionally kept free (and hence protected) by the | |
769 | buddy allocator. Bigger value increase the probability | |
770 | of catching random memory corruption, but reduce the | |
771 | amount of memory for normal system use. The maximum | |
772 | possible value is MAX_ORDER/2. Setting this parameter | |
773 | to 1 or 2 should be enough to identify most random | |
774 | memory corruption problems caused by bugs in kernel or | |
775 | driver code when a CPU writes to (or reads from) a | |
776 | random memory location. Note that there exists a class | |
777 | of memory corruptions problems caused by buggy H/W or | |
778 | F/W or by drivers badly programing DMA (basically when | |
779 | memory is written at bus level and the CPU MMU is | |
780 | bypassed) which are not detectable by | |
781 | CONFIG_DEBUG_PAGEALLOC, hence this option will not help | |
782 | tracking down these problems. | |
783 | ||
784 | debug_pagealloc= | |
785 | [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this | |
786 | parameter enables the feature at boot time. In | |
787 | default, it is disabled. We can avoid allocating huge | |
788 | chunk of memory for debug pagealloc if we don't enable | |
789 | it at boot time and the system will work mostly same | |
790 | with the kernel built without CONFIG_DEBUG_PAGEALLOC. | |
791 | on: enable the feature | |
792 | ||
793 | debugpat [X86] Enable PAT debugging | |
794 | ||
795 | decnet.addr= [HW,NET] | |
796 | Format: <area>[,<node>] | |
797 | See also Documentation/networking/decnet.txt. | |
798 | ||
799 | default_hugepagesz= | |
800 | [same as hugepagesz=] The size of the default | |
801 | HugeTLB page size. This is the size represented by | |
802 | the legacy /proc/ hugepages APIs, used for SHM, and | |
803 | default size when mounting hugetlbfs filesystems. | |
804 | Defaults to the default architecture's huge page size | |
805 | if not specified. | |
806 | ||
807 | dhash_entries= [KNL] | |
808 | Set number of hash buckets for dentry cache. | |
809 | ||
810 | disable_1tb_segments [PPC] | |
811 | Disables the use of 1TB hash page table segments. This | |
812 | causes the kernel to fall back to 256MB segments which | |
813 | can be useful when debugging issues that require an SLB | |
814 | miss to occur. | |
815 | ||
816 | disable= [IPV6] | |
817 | See Documentation/networking/ipv6.txt. | |
818 | ||
819 | disable_radix [PPC] | |
820 | Disable RADIX MMU mode on POWER9 | |
821 | ||
822 | disable_cpu_apicid= [X86,APIC,SMP] | |
823 | Format: <int> | |
824 | The number of initial APIC ID for the | |
825 | corresponding CPU to be disabled at boot, | |
826 | mostly used for the kdump 2nd kernel to | |
827 | disable BSP to wake up multiple CPUs without | |
828 | causing system reset or hang due to sending | |
829 | INIT from AP to BSP. | |
830 | ||
831 | disable_ddw [PPC/PSERIES] | |
832 | Disable Dynamic DMA Window support. Use this if | |
833 | to workaround buggy firmware. | |
834 | ||
835 | disable_ipv6= [IPV6] | |
836 | See Documentation/networking/ipv6.txt. | |
837 | ||
838 | disable_mtrr_cleanup [X86] | |
839 | The kernel tries to adjust MTRR layout from continuous | |
840 | to discrete, to make X server driver able to add WB | |
841 | entry later. This parameter disables that. | |
842 | ||
843 | disable_mtrr_trim [X86, Intel and AMD only] | |
844 | By default the kernel will trim any uncacheable | |
845 | memory out of your available memory pool based on | |
846 | MTRR settings. This parameter disables that behavior, | |
847 | possibly causing your machine to run very slowly. | |
848 | ||
849 | disable_timer_pin_1 [X86] | |
850 | Disable PIN 1 of APIC timer | |
851 | Can be useful to work around chipset bugs. | |
852 | ||
853 | dis_ucode_ldr [X86] Disable the microcode loader. | |
854 | ||
855 | dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, | |
856 | this option disables the debugging code at boot. | |
857 | ||
858 | dma_debug_entries=<number> | |
859 | This option allows to tune the number of preallocated | |
860 | entries for DMA-API debugging code. One entry is | |
861 | required per DMA-API allocation. Use this if the | |
862 | DMA-API debugging code disables itself because the | |
863 | architectural default is too low. | |
864 | ||
865 | dma_debug_driver=<driver_name> | |
866 | With this option the DMA-API debugging driver | |
867 | filter feature can be enabled at boot time. Just | |
868 | pass the driver to filter for as the parameter. | |
869 | The filter can be disabled or changed to another | |
870 | driver later using sysfs. | |
871 | ||
872 | drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] | |
873 | Broken monitors, graphic adapters, KVMs and EDIDless | |
874 | panels may send no or incorrect EDID data sets. | |
875 | This parameter allows to specify an EDID data sets | |
876 | in the /lib/firmware directory that are used instead. | |
877 | Generic built-in EDID data sets are used, if one of | |
878 | edid/1024x768.bin, edid/1280x1024.bin, | |
879 | edid/1680x1050.bin, or edid/1920x1080.bin is given | |
880 | and no file with the same name exists. Details and | |
881 | instructions how to build your own EDID data are | |
882 | available in Documentation/EDID/HOWTO.txt. An EDID | |
883 | data set will only be used for a particular connector, | |
884 | if its name and a colon are prepended to the EDID | |
885 | name. Each connector may use a unique EDID data | |
886 | set by separating the files with a comma. An EDID | |
887 | data set with no connector name will be used for | |
888 | any connectors not explicitly specified. | |
889 | ||
890 | dscc4.setup= [NET] | |
891 | ||
892 | dt_cpu_ftrs= [PPC] | |
893 | Format: {"off" | "known"} | |
894 | Control how the dt_cpu_ftrs device-tree binding is | |
895 | used for CPU feature discovery and setup (if it | |
896 | exists). | |
897 | off: Do not use it, fall back to legacy cpu table. | |
898 | known: Do not pass through unknown features to guests | |
899 | or userspace, only those that the kernel is aware of. | |
900 | ||
901 | dump_apple_properties [X86] | |
902 | Dump name and content of EFI device properties on | |
903 | x86 Macs. Useful for driver authors to determine | |
904 | what data is available or for reverse-engineering. | |
905 | ||
906 | dyndbg[="val"] [KNL,DYNAMIC_DEBUG] | |
907 | module.dyndbg[="val"] | |
908 | Enable debug messages at boot time. See | |
909 | Documentation/admin-guide/dynamic-debug-howto.rst | |
910 | for details. | |
911 | ||
912 | nompx [X86] Disables Intel Memory Protection Extensions. | |
913 | See Documentation/x86/intel_mpx.txt for more | |
914 | information about the feature. | |
915 | ||
916 | nopku [X86] Disable Memory Protection Keys CPU feature found | |
917 | in some Intel CPUs. | |
918 | ||
919 | module.async_probe [KNL] | |
920 | Enable asynchronous probe on this module. | |
921 | ||
922 | early_ioremap_debug [KNL] | |
923 | Enable debug messages in early_ioremap support. This | |
924 | is useful for tracking down temporary early mappings | |
925 | which are not unmapped. | |
926 | ||
927 | earlycon= [KNL] Output early console device and options. | |
928 | ||
929 | [ARM64] The early console is determined by the | |
930 | stdout-path property in device tree's chosen node, | |
931 | or determined by the ACPI SPCR table. | |
932 | ||
933 | [X86] When used with no options the early console is | |
934 | determined by the ACPI SPCR table. | |
935 | ||
936 | cdns,<addr>[,options] | |
937 | Start an early, polled-mode console on a Cadence | |
938 | (xuartps) serial port at the specified address. Only | |
939 | supported option is baud rate. If baud rate is not | |
940 | specified, the serial port must already be setup and | |
941 | configured. | |
942 | ||
943 | uart[8250],io,<addr>[,options] | |
944 | uart[8250],mmio,<addr>[,options] | |
945 | uart[8250],mmio32,<addr>[,options] | |
946 | uart[8250],mmio32be,<addr>[,options] | |
947 | uart[8250],0x<addr>[,options] | |
948 | Start an early, polled-mode console on the 8250/16550 | |
949 | UART at the specified I/O port or MMIO address. | |
950 | MMIO inter-register address stride is either 8-bit | |
951 | (mmio) or 32-bit (mmio32 or mmio32be). | |
952 | If none of [io|mmio|mmio32|mmio32be], <addr> is assumed | |
953 | to be equivalent to 'mmio'. 'options' are specified | |
954 | in the same format described for "console=ttyS<n>"; if | |
955 | unspecified, the h/w is not initialized. | |
956 | ||
957 | pl011,<addr> | |
958 | pl011,mmio32,<addr> | |
959 | Start an early, polled-mode console on a pl011 serial | |
960 | port at the specified address. The pl011 serial port | |
961 | must already be setup and configured. Options are not | |
962 | yet supported. If 'mmio32' is specified, then only | |
963 | the driver will use only 32-bit accessors to read/write | |
964 | the device registers. | |
965 | ||
966 | meson,<addr> | |
967 | Start an early, polled-mode console on a meson serial | |
968 | port at the specified address. The serial port must | |
969 | already be setup and configured. Options are not yet | |
970 | supported. | |
971 | ||
972 | msm_serial,<addr> | |
973 | Start an early, polled-mode console on an msm serial | |
974 | port at the specified address. The serial port | |
975 | must already be setup and configured. Options are not | |
976 | yet supported. | |
977 | ||
978 | msm_serial_dm,<addr> | |
979 | Start an early, polled-mode console on an msm serial | |
980 | dm port at the specified address. The serial port | |
981 | must already be setup and configured. Options are not | |
982 | yet supported. | |
983 | ||
984 | owl,<addr> | |
985 | Start an early, polled-mode console on a serial port | |
986 | of an Actions Semi SoC, such as S500 or S900, at the | |
987 | specified address. The serial port must already be | |
988 | setup and configured. Options are not yet supported. | |
989 | ||
990 | smh Use ARM semihosting calls for early console. | |
991 | ||
992 | s3c2410,<addr> | |
993 | s3c2412,<addr> | |
994 | s3c2440,<addr> | |
995 | s3c6400,<addr> | |
996 | s5pv210,<addr> | |
997 | exynos4210,<addr> | |
998 | Use early console provided by serial driver available | |
999 | on Samsung SoCs, requires selecting proper type and | |
1000 | a correct base address of the selected UART port. The | |
1001 | serial port must already be setup and configured. | |
1002 | Options are not yet supported. | |
1003 | ||
1004 | lantiq,<addr> | |
1005 | Start an early, polled-mode console on a lantiq serial | |
1006 | (lqasc) port at the specified address. The serial port | |
1007 | must already be setup and configured. Options are not | |
1008 | yet supported. | |
1009 | ||
1010 | lpuart,<addr> | |
1011 | lpuart32,<addr> | |
1012 | Use early console provided by Freescale LP UART driver | |
1013 | found on Freescale Vybrid and QorIQ LS1021A processors. | |
1014 | A valid base address must be provided, and the serial | |
1015 | port must already be setup and configured. | |
1016 | ||
1017 | ar3700_uart,<addr> | |
1018 | Start an early, polled-mode console on the | |
1019 | Armada 3700 serial port at the specified | |
1020 | address. The serial port must already be setup | |
1021 | and configured. Options are not yet supported. | |
1022 | ||
1023 | qcom_geni,<addr> | |
1024 | Start an early, polled-mode console on a Qualcomm | |
1025 | Generic Interface (GENI) based serial port at the | |
1026 | specified address. The serial port must already be | |
1027 | setup and configured. Options are not yet supported. | |
1028 | ||
1029 | earlyprintk= [X86,SH,ARM,M68k,S390] | |
1030 | earlyprintk=vga | |
1031 | earlyprintk=efi | |
1032 | earlyprintk=sclp | |
1033 | earlyprintk=xen | |
1034 | earlyprintk=serial[,ttySn[,baudrate]] | |
1035 | earlyprintk=serial[,0x...[,baudrate]] | |
1036 | earlyprintk=ttySn[,baudrate] | |
1037 | earlyprintk=dbgp[debugController#] | |
1038 | earlyprintk=pciserial,bus:device.function[,baudrate] | |
1039 | earlyprintk=xdbc[xhciController#] | |
1040 | ||
1041 | earlyprintk is useful when the kernel crashes before | |
1042 | the normal console is initialized. It is not enabled by | |
1043 | default because it has some cosmetic problems. | |
1044 | ||
1045 | Append ",keep" to not disable it when the real console | |
1046 | takes over. | |
1047 | ||
1048 | Only one of vga, efi, serial, or usb debug port can | |
1049 | be used at a time. | |
1050 | ||
1051 | Currently only ttyS0 and ttyS1 may be specified by | |
1052 | name. Other I/O ports may be explicitly specified | |
1053 | on some architectures (x86 and arm at least) by | |
1054 | replacing ttySn with an I/O port address, like this: | |
1055 | earlyprintk=serial,0x1008,115200 | |
1056 | You can find the port for a given device in | |
1057 | /proc/tty/driver/serial: | |
1058 | 2: uart:ST16650V2 port:00001008 irq:18 ... | |
1059 | ||
1060 | Interaction with the standard serial driver is not | |
1061 | very good. | |
1062 | ||
1063 | The VGA and EFI output is eventually overwritten by | |
1064 | the real console. | |
1065 | ||
1066 | The xen output can only be used by Xen PV guests. | |
1067 | ||
1068 | The sclp output can only be used on s390. | |
1069 | ||
1070 | edac_report= [HW,EDAC] Control how to report EDAC event | |
1071 | Format: {"on" | "off" | "force"} | |
1072 | on: enable EDAC to report H/W event. May be overridden | |
1073 | by other higher priority error reporting module. | |
1074 | off: disable H/W event reporting through EDAC. | |
1075 | force: enforce the use of EDAC to report H/W event. | |
1076 | default: on. | |
1077 | ||
1078 | ekgdboc= [X86,KGDB] Allow early kernel console debugging | |
1079 | ekgdboc=kbd | |
1080 | ||
1081 | This is designed to be used in conjunction with | |
1082 | the boot argument: earlyprintk=vga | |
1083 | ||
1084 | edd= [EDD] | |
1085 | Format: {"off" | "on" | "skip[mbr]"} | |
1086 | ||
1087 | efi= [EFI] | |
1088 | Format: { "old_map", "nochunk", "noruntime", "debug" } | |
1089 | old_map [X86-64]: switch to the old ioremap-based EFI | |
1090 | runtime services mapping. 32-bit still uses this one by | |
1091 | default. | |
1092 | nochunk: disable reading files in "chunks" in the EFI | |
1093 | boot stub, as chunking can cause problems with some | |
1094 | firmware implementations. | |
1095 | noruntime : disable EFI runtime services support | |
1096 | debug: enable misc debug output | |
1097 | ||
1098 | efi_no_storage_paranoia [EFI; X86] | |
1099 | Using this parameter you can use more than 50% of | |
1100 | your efi variable storage. Use this parameter only if | |
1101 | you are really sure that your UEFI does sane gc and | |
1102 | fulfills the spec otherwise your board may brick. | |
1103 | ||
1104 | efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86] | |
1105 | Add arbitrary attribute to specific memory range by | |
1106 | updating original EFI memory map. | |
1107 | Region of memory which aa attribute is added to is | |
1108 | from ss to ss+nn. | |
1109 | If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000 | |
1110 | is specified, EFI_MEMORY_MORE_RELIABLE(0x10000) | |
1111 | attribute is added to range 0x100000000-0x180000000 and | |
1112 | 0x10a0000000-0x1120000000. | |
1113 | ||
1114 | Using this parameter you can do debugging of EFI memmap | |
1115 | related feature. For example, you can do debugging of | |
1116 | Address Range Mirroring feature even if your box | |
1117 | doesn't support it. | |
1118 | ||
1119 | efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT | |
1120 | that is to be dynamically loaded by Linux. If there are | |
1121 | multiple variables with the same name but with different | |
1122 | vendor GUIDs, all of them will be loaded. See | |
1123 | Documentation/acpi/ssdt-overlays.txt for details. | |
1124 | ||
1125 | ||
1126 | eisa_irq_edge= [PARISC,HW] | |
1127 | See header of drivers/parisc/eisa.c. | |
1128 | ||
1129 | elanfreq= [X86-32] | |
1130 | See comment before function elanfreq_setup() in | |
1131 | arch/x86/kernel/cpu/cpufreq/elanfreq.c. | |
1132 | ||
1133 | elevator= [IOSCHED] | |
1134 | Format: {"cfq" | "deadline" | "noop"} | |
1135 | See Documentation/block/cfq-iosched.txt and | |
1136 | Documentation/block/deadline-iosched.txt for details. | |
1137 | ||
1138 | elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] | |
1139 | Specifies physical address of start of kernel core | |
1140 | image elf header and optionally the size. Generally | |
1141 | kexec loader will pass this option to capture kernel. | |
1142 | See Documentation/kdump/kdump.txt for details. | |
1143 | ||
1144 | enable_mtrr_cleanup [X86] | |
1145 | The kernel tries to adjust MTRR layout from continuous | |
1146 | to discrete, to make X server driver able to add WB | |
1147 | entry later. This parameter enables that. | |
1148 | ||
1149 | enable_timer_pin_1 [X86] | |
1150 | Enable PIN 1 of APIC timer | |
1151 | Can be useful to work around chipset bugs | |
1152 | (in particular on some ATI chipsets). | |
1153 | The kernel tries to set a reasonable default. | |
1154 | ||
1155 | enforcing [SELINUX] Set initial enforcing status. | |
1156 | Format: {"0" | "1"} | |
1157 | See security/selinux/Kconfig help text. | |
1158 | 0 -- permissive (log only, no denials). | |
1159 | 1 -- enforcing (deny and log). | |
1160 | Default value is 0. | |
1161 | Value can be changed at runtime via /selinux/enforce. | |
1162 | ||
1163 | erst_disable [ACPI] | |
1164 | Disable Error Record Serialization Table (ERST) | |
1165 | support. | |
1166 | ||
1167 | ether= [HW,NET] Ethernet cards parameters | |
1168 | This option is obsoleted by the "netdev=" option, which | |
1169 | has equivalent usage. See its documentation for details. | |
1170 | ||
1171 | evm= [EVM] | |
1172 | Format: { "fix" } | |
1173 | Permit 'security.evm' to be updated regardless of | |
1174 | current integrity status. | |
1175 | ||
1176 | failslab= | |
1177 | fail_page_alloc= | |
1178 | fail_make_request=[KNL] | |
1179 | General fault injection mechanism. | |
1180 | Format: <interval>,<probability>,<space>,<times> | |
1181 | See also Documentation/fault-injection/. | |
1182 | ||
1183 | floppy= [HW] | |
1184 | See Documentation/blockdev/floppy.txt. | |
1185 | ||
1186 | force_pal_cache_flush | |
1187 | [IA-64] Avoid check_sal_cache_flush which may hang on | |
1188 | buggy SAL_CACHE_FLUSH implementations. Using this | |
1189 | parameter will force ia64_sal_cache_flush to call | |
1190 | ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. | |
1191 | ||
1192 | forcepae [X86-32] | |
1193 | Forcefully enable Physical Address Extension (PAE). | |
1194 | Many Pentium M systems disable PAE but may have a | |
1195 | functionally usable PAE implementation. | |
1196 | Warning: use of this parameter will taint the kernel | |
1197 | and may cause unknown problems. | |
1198 | ||
1199 | ftrace=[tracer] | |
1200 | [FTRACE] will set and start the specified tracer | |
1201 | as early as possible in order to facilitate early | |
1202 | boot debugging. | |
1203 | ||
1204 | ftrace_dump_on_oops[=orig_cpu] | |
1205 | [FTRACE] will dump the trace buffers on oops. | |
1206 | If no parameter is passed, ftrace will dump | |
1207 | buffers of all CPUs, but if you pass orig_cpu, it will | |
1208 | dump only the buffer of the CPU that triggered the | |
1209 | oops. | |
1210 | ||
1211 | ftrace_filter=[function-list] | |
1212 | [FTRACE] Limit the functions traced by the function | |
1213 | tracer at boot up. function-list is a comma separated | |
1214 | list of functions. This list can be changed at run | |
1215 | time by the set_ftrace_filter file in the debugfs | |
1216 | tracing directory. | |
1217 | ||
1218 | ftrace_notrace=[function-list] | |
1219 | [FTRACE] Do not trace the functions specified in | |
1220 | function-list. This list can be changed at run time | |
1221 | by the set_ftrace_notrace file in the debugfs | |
1222 | tracing directory. | |
1223 | ||
1224 | ftrace_graph_filter=[function-list] | |
1225 | [FTRACE] Limit the top level callers functions traced | |
1226 | by the function graph tracer at boot up. | |
1227 | function-list is a comma separated list of functions | |
1228 | that can be changed at run time by the | |
1229 | set_graph_function file in the debugfs tracing directory. | |
1230 | ||
1231 | ftrace_graph_notrace=[function-list] | |
1232 | [FTRACE] Do not trace from the functions specified in | |
1233 | function-list. This list is a comma separated list of | |
1234 | functions that can be changed at run time by the | |
1235 | set_graph_notrace file in the debugfs tracing directory. | |
1236 | ||
1237 | ftrace_graph_max_depth=<uint> | |
1238 | [FTRACE] Used with the function graph tracer. This is | |
1239 | the max depth it will trace into a function. This value | |
1240 | can be changed at run time by the max_graph_depth file | |
1241 | in the tracefs tracing directory. default: 0 (no limit) | |
1242 | ||
1243 | gamecon.map[2|3]= | |
1244 | [HW,JOY] Multisystem joystick and NES/SNES/PSX pad | |
1245 | support via parallel port (up to 5 devices per port) | |
1246 | Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> | |
1247 | See also Documentation/input/devices/joystick-parport.rst | |
1248 | ||
1249 | gamma= [HW,DRM] | |
1250 | ||
1251 | gart_fix_e820= [X86_64] disable the fix e820 for K8 GART | |
1252 | Format: off | on | |
1253 | default: on | |
1254 | ||
1255 | gcov_persist= [GCOV] When non-zero (default), profiling data for | |
1256 | kernel modules is saved and remains accessible via | |
1257 | debugfs, even when the module is unloaded/reloaded. | |
1258 | When zero, profiling data is discarded and associated | |
1259 | debugfs files are removed at module unload time. | |
1260 | ||
1261 | goldfish [X86] Enable the goldfish android emulator platform. | |
1262 | Don't use this when you are not running on the | |
1263 | android emulator | |
1264 | ||
1265 | gpt [EFI] Forces disk with valid GPT signature but | |
1266 | invalid Protective MBR to be treated as GPT. If the | |
1267 | primary GPT is corrupted, it enables the backup/alternate | |
1268 | GPT to be used instead. | |
1269 | ||
1270 | grcan.enable0= [HW] Configuration of physical interface 0. Determines | |
1271 | the "Enable 0" bit of the configuration register. | |
1272 | Format: 0 | 1 | |
1273 | Default: 0 | |
1274 | grcan.enable1= [HW] Configuration of physical interface 1. Determines | |
1275 | the "Enable 0" bit of the configuration register. | |
1276 | Format: 0 | 1 | |
1277 | Default: 0 | |
1278 | grcan.select= [HW] Select which physical interface to use. | |
1279 | Format: 0 | 1 | |
1280 | Default: 0 | |
1281 | grcan.txsize= [HW] Sets the size of the tx buffer. | |
1282 | Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0. | |
1283 | Default: 1024 | |
1284 | grcan.rxsize= [HW] Sets the size of the rx buffer. | |
1285 | Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. | |
1286 | Default: 1024 | |
1287 | ||
1288 | gpio-mockup.gpio_mockup_ranges | |
1289 | [HW] Sets the ranges of gpiochip of for this device. | |
1290 | Format: <start1>,<end1>,<start2>,<end2>... | |
1291 | ||
1292 | hardlockup_all_cpu_backtrace= | |
1293 | [KNL] Should the hard-lockup detector generate | |
1294 | backtraces on all cpus. | |
1295 | Format: <integer> | |
1296 | ||
1297 | hashdist= [KNL,NUMA] Large hashes allocated during boot | |
1298 | are distributed across NUMA nodes. Defaults on | |
1299 | for 64-bit NUMA, off otherwise. | |
1300 | Format: 0 | 1 (for off | on) | |
1301 | ||
1302 | hcl= [IA-64] SGI's Hardware Graph compatibility layer | |
1303 | ||
1304 | hd= [EIDE] (E)IDE hard drive subsystem geometry | |
1305 | Format: <cyl>,<head>,<sect> | |
1306 | ||
1307 | hest_disable [ACPI] | |
1308 | Disable Hardware Error Source Table (HEST) support; | |
1309 | corresponding firmware-first mode error processing | |
1310 | logic will be disabled. | |
1311 | ||
1312 | highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact | |
1313 | size of <nn>. This works even on boxes that have no | |
1314 | highmem otherwise. This also works to reduce highmem | |
1315 | size on bigger boxes. | |
1316 | ||
1317 | highres= [KNL] Enable/disable high resolution timer mode. | |
1318 | Valid parameters: "on", "off" | |
1319 | Default: "on" | |
1320 | ||
1321 | hisax= [HW,ISDN] | |
1322 | See Documentation/isdn/README.HiSax. | |
1323 | ||
1324 | hlt [BUGS=ARM,SH] | |
1325 | ||
1326 | hpet= [X86-32,HPET] option to control HPET usage | |
1327 | Format: { enable (default) | disable | force | | |
1328 | verbose } | |
1329 | disable: disable HPET and use PIT instead | |
1330 | force: allow force enabled of undocumented chips (ICH4, | |
1331 | VIA, nVidia) | |
1332 | verbose: show contents of HPET registers during setup | |
1333 | ||
1334 | hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET | |
1335 | registers. Default set by CONFIG_HPET_MMAP_DEFAULT. | |
1336 | ||
1337 | hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. | |
1338 | hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. | |
1339 | On x86-64 and powerpc, this option can be specified | |
1340 | multiple times interleaved with hugepages= to reserve | |
1341 | huge pages of different sizes. Valid pages sizes on | |
1342 | x86-64 are 2M (when the CPU supports "pse") and 1G | |
1343 | (when the CPU supports the "pdpe1gb" cpuinfo flag). | |
1344 | ||
1345 | hung_task_panic= | |
1346 | [KNL] Should the hung task detector generate panics. | |
1347 | Format: <integer> | |
1348 | ||
1349 | A nonzero value instructs the kernel to panic when a | |
1350 | hung task is detected. The default value is controlled | |
1351 | by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time | |
1352 | option. The value selected by this boot parameter can | |
1353 | be changed later by the kernel.hung_task_panic sysctl. | |
1354 | ||
1355 | hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) | |
1356 | terminal devices. Valid values: 0..8 | |
1357 | hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. | |
1358 | If specified, z/VM IUCV HVC accepts connections | |
1359 | from listed z/VM user IDs only. | |
1360 | keep_bootcon [KNL] | |
1361 | Do not unregister boot console at start. This is only | |
1362 | useful for debugging when something happens in the window | |
1363 | between unregistering the boot console and initializing | |
1364 | the real console. | |
1365 | ||
1366 | i2c_bus= [HW] Override the default board specific I2C bus speed | |
1367 | or register an additional I2C bus that is not | |
1368 | registered from board initialization code. | |
1369 | Format: | |
1370 | <bus_id>,<clkrate> | |
1371 | ||
1372 | i8042.debug [HW] Toggle i8042 debug mode | |
1373 | i8042.unmask_kbd_data | |
1374 | [HW] Enable printing of interrupt data from the KBD port | |
1375 | (disabled by default, and as a pre-condition | |
1376 | requires that i8042.debug=1 be enabled) | |
1377 | i8042.direct [HW] Put keyboard port into non-translated mode | |
1378 | i8042.dumbkbd [HW] Pretend that controller can only read data from | |
1379 | keyboard and cannot control its state | |
1380 | (Don't attempt to blink the leds) | |
1381 | i8042.noaux [HW] Don't check for auxiliary (== mouse) port | |
1382 | i8042.nokbd [HW] Don't check/create keyboard port | |
1383 | i8042.noloop [HW] Disable the AUX Loopback command while probing | |
1384 | for the AUX port | |
1385 | i8042.nomux [HW] Don't check presence of an active multiplexing | |
1386 | controller | |
1387 | i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX | |
1388 | controllers | |
1389 | i8042.notimeout [HW] Ignore timeout condition signalled by controller | |
1390 | i8042.reset [HW] Reset the controller during init, cleanup and | |
1391 | suspend-to-ram transitions, only during s2r | |
1392 | transitions, or never reset | |
1393 | Format: { 1 | Y | y | 0 | N | n } | |
1394 | 1, Y, y: always reset controller | |
1395 | 0, N, n: don't ever reset controller | |
1396 | Default: only on s2r transitions on x86; most other | |
1397 | architectures force reset to be always executed | |
1398 | i8042.unlock [HW] Unlock (ignore) the keylock | |
1399 | i8042.kbdreset [HW] Reset device connected to KBD port | |
1400 | ||
1401 | i810= [HW,DRM] | |
1402 | ||
1403 | i8k.ignore_dmi [HW] Continue probing hardware even if DMI data | |
1404 | indicates that the driver is running on unsupported | |
1405 | hardware. | |
1406 | i8k.force [HW] Activate i8k driver even if SMM BIOS signature | |
1407 | does not match list of supported models. | |
1408 | i8k.power_status | |
1409 | [HW] Report power status in /proc/i8k | |
1410 | (disabled by default) | |
1411 | i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN | |
1412 | capability is set. | |
1413 | ||
1414 | i915.invert_brightness= | |
1415 | [DRM] Invert the sense of the variable that is used to | |
1416 | set the brightness of the panel backlight. Normally a | |
1417 | brightness value of 0 indicates backlight switched off, | |
1418 | and the maximum of the brightness value sets the backlight | |
1419 | to maximum brightness. If this parameter is set to 0 | |
1420 | (default) and the machine requires it, or this parameter | |
1421 | is set to 1, a brightness value of 0 sets the backlight | |
1422 | to maximum brightness, and the maximum of the brightness | |
1423 | value switches the backlight off. | |
1424 | -1 -- never invert brightness | |
1425 | 0 -- machine default | |
1426 | 1 -- force brightness inversion | |
1427 | ||
1428 | icn= [HW,ISDN] | |
1429 | Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] | |
1430 | ||
1431 | ide-core.nodma= [HW] (E)IDE subsystem | |
1432 | Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc | |
1433 | .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr | |
1434 | .cdrom .chs .ignore_cable are additional options | |
1435 | See Documentation/ide/ide.txt. | |
1436 | ||
1437 | ide-generic.probe-mask= [HW] (E)IDE subsystem | |
1438 | Format: <int> | |
1439 | Probe mask for legacy ISA IDE ports. Depending on | |
1440 | platform up to 6 ports are supported, enabled by | |
1441 | setting corresponding bits in the mask to 1. The | |
1442 | default value is 0x0, which has a special meaning. | |
1443 | On systems that have PCI, it triggers scanning the | |
1444 | PCI bus for the first and the second port, which | |
1445 | are then probed. On systems without PCI the value | |
1446 | of 0x0 enables probing the two first ports as if it | |
1447 | was 0x3. | |
1448 | ||
1449 | ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem | |
1450 | Claim all unknown PCI IDE storage controllers. | |
1451 | ||
1452 | idle= [X86] | |
1453 | Format: idle=poll, idle=halt, idle=nomwait | |
1454 | Poll forces a polling idle loop that can slightly | |
1455 | improve the performance of waking up a idle CPU, but | |
1456 | will use a lot of power and make the system run hot. | |
1457 | Not recommended. | |
1458 | idle=halt: Halt is forced to be used for CPU idle. | |
1459 | In such case C2/C3 won't be used again. | |
1460 | idle=nomwait: Disable mwait for CPU C-states | |
1461 | ||
1462 | ieee754= [MIPS] Select IEEE Std 754 conformance mode | |
1463 | Format: { strict | legacy | 2008 | relaxed } | |
1464 | Default: strict | |
1465 | ||
1466 | Choose which programs will be accepted for execution | |
1467 | based on the IEEE 754 NaN encoding(s) supported by | |
1468 | the FPU and the NaN encoding requested with the value | |
1469 | of an ELF file header flag individually set by each | |
1470 | binary. Hardware implementations are permitted to | |
1471 | support either or both of the legacy and the 2008 NaN | |
1472 | encoding mode. | |
1473 | ||
1474 | Available settings are as follows: | |
1475 | strict accept binaries that request a NaN encoding | |
1476 | supported by the FPU | |
1477 | legacy only accept legacy-NaN binaries, if supported | |
1478 | by the FPU | |
1479 | 2008 only accept 2008-NaN binaries, if supported | |
1480 | by the FPU | |
1481 | relaxed accept any binaries regardless of whether | |
1482 | supported by the FPU | |
1483 | ||
1484 | The FPU emulator is always able to support both NaN | |
1485 | encodings, so if no FPU hardware is present or it has | |
1486 | been disabled with 'nofpu', then the settings of | |
1487 | 'legacy' and '2008' strap the emulator accordingly, | |
1488 | 'relaxed' straps the emulator for both legacy-NaN and | |
1489 | 2008-NaN, whereas 'strict' enables legacy-NaN only on | |
1490 | legacy processors and both NaN encodings on MIPS32 or | |
1491 | MIPS64 CPUs. | |
1492 | ||
1493 | The setting for ABS.fmt/NEG.fmt instruction execution | |
1494 | mode generally follows that for the NaN encoding, | |
1495 | except where unsupported by hardware. | |
1496 | ||
1497 | ignore_loglevel [KNL] | |
1498 | Ignore loglevel setting - this will print /all/ | |
1499 | kernel messages to the console. Useful for debugging. | |
1500 | We also add it as printk module parameter, so users | |
1501 | could change it dynamically, usually by | |
1502 | /sys/module/printk/parameters/ignore_loglevel. | |
1503 | ||
1504 | ignore_rlimit_data | |
1505 | Ignore RLIMIT_DATA setting for data mappings, | |
1506 | print warning at first misuse. Can be changed via | |
1507 | /sys/module/kernel/parameters/ignore_rlimit_data. | |
1508 | ||
1509 | ihash_entries= [KNL] | |
1510 | Set number of hash buckets for inode cache. | |
1511 | ||
1512 | ima_appraise= [IMA] appraise integrity measurements | |
1513 | Format: { "off" | "enforce" | "fix" | "log" } | |
1514 | default: "enforce" | |
1515 | ||
1516 | ima_appraise_tcb [IMA] | |
1517 | The builtin appraise policy appraises all files | |
1518 | owned by uid=0. | |
1519 | ||
1520 | ima_canonical_fmt [IMA] | |
1521 | Use the canonical format for the binary runtime | |
1522 | measurements, instead of host native format. | |
1523 | ||
1524 | ima_hash= [IMA] | |
1525 | Format: { md5 | sha1 | rmd160 | sha256 | sha384 | |
1526 | | sha512 | ... } | |
1527 | default: "sha1" | |
1528 | ||
1529 | The list of supported hash algorithms is defined | |
1530 | in crypto/hash_info.h. | |
1531 | ||
1532 | ima_policy= [IMA] | |
1533 | The builtin policies to load during IMA setup. | |
1534 | Format: "tcb | appraise_tcb | secure_boot | | |
1535 | fail_securely" | |
1536 | ||
1537 | The "tcb" policy measures all programs exec'd, files | |
1538 | mmap'd for exec, and all files opened with the read | |
1539 | mode bit set by either the effective uid (euid=0) or | |
1540 | uid=0. | |
1541 | ||
1542 | The "appraise_tcb" policy appraises the integrity of | |
1543 | all files owned by root. (This is the equivalent | |
1544 | of ima_appraise_tcb.) | |
1545 | ||
1546 | The "secure_boot" policy appraises the integrity | |
1547 | of files (eg. kexec kernel image, kernel modules, | |
1548 | firmware, policy, etc) based on file signatures. | |
1549 | ||
1550 | The "fail_securely" policy forces file signature | |
1551 | verification failure also on privileged mounted | |
1552 | filesystems with the SB_I_UNVERIFIABLE_SIGNATURE | |
1553 | flag. | |
1554 | ||
1555 | ima_tcb [IMA] Deprecated. Use ima_policy= instead. | |
1556 | Load a policy which meets the needs of the Trusted | |
1557 | Computing Base. This means IMA will measure all | |
1558 | programs exec'd, files mmap'd for exec, and all files | |
1559 | opened for read by uid=0. | |
1560 | ||
1561 | ima_template= [IMA] | |
1562 | Select one of defined IMA measurements template formats. | |
1563 | Formats: { "ima" | "ima-ng" | "ima-sig" } | |
1564 | Default: "ima-ng" | |
1565 | ||
1566 | ima_template_fmt= | |
1567 | [IMA] Define a custom template format. | |
1568 | Format: { "field1|...|fieldN" } | |
1569 | ||
1570 | ima.ahash_minsize= [IMA] Minimum file size for asynchronous hash usage | |
1571 | Format: <min_file_size> | |
1572 | Set the minimal file size for using asynchronous hash. | |
1573 | If left unspecified, ahash usage is disabled. | |
1574 | ||
1575 | ahash performance varies for different data sizes on | |
1576 | different crypto accelerators. This option can be used | |
1577 | to achieve the best performance for a particular HW. | |
1578 | ||
1579 | ima.ahash_bufsize= [IMA] Asynchronous hash buffer size | |
1580 | Format: <bufsize> | |
1581 | Set hashing buffer size. Default: 4k. | |
1582 | ||
1583 | ahash performance varies for different chunk sizes on | |
1584 | different crypto accelerators. This option can be used | |
1585 | to achieve best performance for particular HW. | |
1586 | ||
1587 | init= [KNL] | |
1588 | Format: <full_path> | |
1589 | Run specified binary instead of /sbin/init as init | |
1590 | process. | |
1591 | ||
1592 | initcall_debug [KNL] Trace initcalls as they are executed. Useful | |
1593 | for working out where the kernel is dying during | |
1594 | startup. | |
1595 | ||
1596 | initcall_blacklist= [KNL] Do not execute a comma-separated list of | |
1597 | initcall functions. Useful for debugging built-in | |
1598 | modules and initcalls. | |
1599 | ||
1600 | initrd= [BOOT] Specify the location of the initial ramdisk | |
1601 | ||
1602 | init_pkru= [x86] Specify the default memory protection keys rights | |
1603 | register contents for all processes. 0x55555554 by | |
1604 | default (disallow access to all but pkey 0). Can | |
1605 | override in debugfs after boot. | |
1606 | ||
1607 | inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver | |
1608 | Format: <irq> | |
1609 | ||
1610 | int_pln_enable [x86] Enable power limit notification interrupt | |
1611 | ||
1612 | integrity_audit=[IMA] | |
1613 | Format: { "0" | "1" } | |
1614 | 0 -- basic integrity auditing messages. (Default) | |
1615 | 1 -- additional integrity auditing messages. | |
1616 | ||
1617 | intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option | |
1618 | on | |
1619 | Enable intel iommu driver. | |
1620 | off | |
1621 | Disable intel iommu driver. | |
1622 | igfx_off [Default Off] | |
1623 | By default, gfx is mapped as normal device. If a gfx | |
1624 | device has a dedicated DMAR unit, the DMAR unit is | |
1625 | bypassed by not enabling DMAR with this option. In | |
1626 | this case, gfx device will use physical address for | |
1627 | DMA. | |
1628 | forcedac [x86_64] | |
1629 | With this option iommu will not optimize to look | |
1630 | for io virtual address below 32-bit forcing dual | |
1631 | address cycle on pci bus for cards supporting greater | |
1632 | than 32-bit addressing. The default is to look | |
1633 | for translation below 32-bit and if not available | |
1634 | then look in the higher range. | |
1635 | strict [Default Off] | |
1636 | With this option on every unmap_single operation will | |
1637 | result in a hardware IOTLB flush operation as opposed | |
1638 | to batching them for performance. | |
1639 | sp_off [Default Off] | |
1640 | By default, super page will be supported if Intel IOMMU | |
1641 | has the capability. With this option, super page will | |
1642 | not be supported. | |
1643 | ecs_off [Default Off] | |
1644 | By default, extended context tables will be supported if | |
1645 | the hardware advertises that it has support both for the | |
1646 | extended tables themselves, and also PASID support. With | |
1647 | this option set, extended tables will not be used even | |
1648 | on hardware which claims to support them. | |
1649 | tboot_noforce [Default Off] | |
1650 | Do not force the Intel IOMMU enabled under tboot. | |
1651 | By default, tboot will force Intel IOMMU on, which | |
1652 | could harm performance of some high-throughput | |
1653 | devices like 40GBit network cards, even if identity | |
1654 | mapping is enabled. | |
1655 | Note that using this option lowers the security | |
1656 | provided by tboot because it makes the system | |
1657 | vulnerable to DMA attacks. | |
1658 | ||
1659 | intel_idle.max_cstate= [KNL,HW,ACPI,X86] | |
1660 | 0 disables intel_idle and fall back on acpi_idle. | |
1661 | 1 to 9 specify maximum depth of C-state. | |
1662 | ||
1663 | intel_pstate= [X86] | |
1664 | disable | |
1665 | Do not enable intel_pstate as the default | |
1666 | scaling driver for the supported processors | |
1667 | passive | |
1668 | Use intel_pstate as a scaling driver, but configure it | |
1669 | to work with generic cpufreq governors (instead of | |
1670 | enabling its internal governor). This mode cannot be | |
1671 | used along with the hardware-managed P-states (HWP) | |
1672 | feature. | |
1673 | force | |
1674 | Enable intel_pstate on systems that prohibit it by default | |
1675 | in favor of acpi-cpufreq. Forcing the intel_pstate driver | |
1676 | instead of acpi-cpufreq may disable platform features, such | |
1677 | as thermal controls and power capping, that rely on ACPI | |
1678 | P-States information being indicated to OSPM and therefore | |
1679 | should be used with caution. This option does not work with | |
1680 | processors that aren't supported by the intel_pstate driver | |
1681 | or on platforms that use pcc-cpufreq instead of acpi-cpufreq. | |
1682 | no_hwp | |
1683 | Do not enable hardware P state control (HWP) | |
1684 | if available. | |
1685 | hwp_only | |
1686 | Only load intel_pstate on systems which support | |
1687 | hardware P state control (HWP) if available. | |
1688 | support_acpi_ppc | |
1689 | Enforce ACPI _PPC performance limits. If the Fixed ACPI | |
1690 | Description Table, specifies preferred power management | |
1691 | profile as "Enterprise Server" or "Performance Server", | |
1692 | then this feature is turned on by default. | |
1693 | per_cpu_perf_limits | |
1694 | Allow per-logical-CPU P-State performance control limits using | |
1695 | cpufreq sysfs interface | |
1696 | ||
1697 | intremap= [X86-64, Intel-IOMMU] | |
1698 | on enable Interrupt Remapping (default) | |
1699 | off disable Interrupt Remapping | |
1700 | nosid disable Source ID checking | |
1701 | no_x2apic_optout | |
1702 | BIOS x2APIC opt-out request will be ignored | |
1703 | nopost disable Interrupt Posting | |
1704 | ||
1705 | iomem= Disable strict checking of access to MMIO memory | |
1706 | strict regions from userspace. | |
1707 | relaxed | |
1708 | ||
1709 | iommu= [x86] | |
1710 | off | |
1711 | force | |
1712 | noforce | |
1713 | biomerge | |
1714 | panic | |
1715 | nopanic | |
1716 | merge | |
1717 | nomerge | |
1718 | soft | |
1719 | pt [x86, IA-64] | |
1720 | nobypass [PPC/POWERNV] | |
1721 | Disable IOMMU bypass, using IOMMU for PCI devices. | |
1722 | ||
1723 | iommu.passthrough= | |
1724 | [ARM64] Configure DMA to bypass the IOMMU by default. | |
1725 | Format: { "0" | "1" } | |
1726 | 0 - Use IOMMU translation for DMA. | |
1727 | 1 - Bypass the IOMMU for DMA. | |
1728 | unset - Use IOMMU translation for DMA. | |
1729 | ||
1730 | io7= [HW] IO7 for Marvel based alpha systems | |
1731 | See comment before marvel_specify_io7 in | |
1732 | arch/alpha/kernel/core_marvel.c. | |
1733 | ||
1734 | io_delay= [X86] I/O delay method | |
1735 | 0x80 | |
1736 | Standard port 0x80 based delay | |
1737 | 0xed | |
1738 | Alternate port 0xed based delay (needed on some systems) | |
1739 | udelay | |
1740 | Simple two microseconds delay | |
1741 | none | |
1742 | No delay | |
1743 | ||
1744 | ip= [IP_PNP] | |
1745 | See Documentation/filesystems/nfs/nfsroot.txt. | |
1746 | ||
1747 | irqaffinity= [SMP] Set the default irq affinity mask | |
1748 | The argument is a cpu list, as described above. | |
1749 | ||
1750 | irqchip.gicv2_force_probe= | |
1751 | [ARM, ARM64] | |
1752 | Format: <bool> | |
1753 | Force the kernel to look for the second 4kB page | |
1754 | of a GICv2 controller even if the memory range | |
1755 | exposed by the device tree is too small. | |
1756 | ||
1757 | irqchip.gicv3_nolpi= | |
1758 | [ARM, ARM64] | |
1759 | Force the kernel to ignore the availability of | |
1760 | LPIs (and by consequence ITSs). Intended for system | |
1761 | that use the kernel as a bootloader, and thus want | |
1762 | to let secondary kernels in charge of setting up | |
1763 | LPIs. | |
1764 | ||
1765 | irqfixup [HW] | |
1766 | When an interrupt is not handled search all handlers | |
1767 | for it. Intended to get systems with badly broken | |
1768 | firmware running. | |
1769 | ||
1770 | irqpoll [HW] | |
1771 | When an interrupt is not handled search all handlers | |
1772 | for it. Also check all handlers each timer | |
1773 | interrupt. Intended to get systems with badly broken | |
1774 | firmware running. | |
1775 | ||
1776 | isapnp= [ISAPNP] | |
1777 | Format: <RDP>,<reset>,<pci_scan>,<verbosity> | |
1778 | ||
1779 | isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance. | |
1780 | [Deprecated - use cpusets instead] | |
1781 | Format: [flag-list,]<cpu-list> | |
1782 | ||
1783 | Specify one or more CPUs to isolate from disturbances | |
1784 | specified in the flag list (default: domain): | |
1785 | ||
1786 | nohz | |
1787 | Disable the tick when a single task runs. | |
1788 | ||
1789 | A residual 1Hz tick is offloaded to workqueues, which you | |
1790 | need to affine to housekeeping through the global | |
1791 | workqueue's affinity configured via the | |
1792 | /sys/devices/virtual/workqueue/cpumask sysfs file, or | |
1793 | by using the 'domain' flag described below. | |
1794 | ||
1795 | NOTE: by default the global workqueue runs on all CPUs, | |
1796 | so to protect individual CPUs the 'cpumask' file has to | |
1797 | be configured manually after bootup. | |
1798 | ||
1799 | domain | |
1800 | Isolate from the general SMP balancing and scheduling | |
1801 | algorithms. Note that performing domain isolation this way | |
1802 | is irreversible: it's not possible to bring back a CPU to | |
1803 | the domains once isolated through isolcpus. It's strongly | |
1804 | advised to use cpusets instead to disable scheduler load | |
1805 | balancing through the "cpuset.sched_load_balance" file. | |
1806 | It offers a much more flexible interface where CPUs can | |
1807 | move in and out of an isolated set anytime. | |
1808 | ||
1809 | You can move a process onto or off an "isolated" CPU via | |
1810 | the CPU affinity syscalls or cpuset. | |
1811 | <cpu number> begins at 0 and the maximum value is | |
1812 | "number of CPUs in system - 1". | |
1813 | ||
1814 | The format of <cpu-list> is described above. | |
1815 | ||
1816 | ||
1817 | ||
1818 | iucv= [HW,NET] | |
1819 | ||
1820 | ivrs_ioapic [HW,X86_64] | |
1821 | Provide an override to the IOAPIC-ID<->DEVICE-ID | |
1822 | mapping provided in the IVRS ACPI table. For | |
1823 | example, to map IOAPIC-ID decimal 10 to | |
1824 | PCI device 00:14.0 write the parameter as: | |
1825 | ivrs_ioapic[10]=00:14.0 | |
1826 | ||
1827 | ivrs_hpet [HW,X86_64] | |
1828 | Provide an override to the HPET-ID<->DEVICE-ID | |
1829 | mapping provided in the IVRS ACPI table. For | |
1830 | example, to map HPET-ID decimal 0 to | |
1831 | PCI device 00:14.0 write the parameter as: | |
1832 | ivrs_hpet[0]=00:14.0 | |
1833 | ||
1834 | ivrs_acpihid [HW,X86_64] | |
1835 | Provide an override to the ACPI-HID:UID<->DEVICE-ID | |
1836 | mapping provided in the IVRS ACPI table. For | |
1837 | example, to map UART-HID:UID AMD0020:0 to | |
1838 | PCI device 00:14.5 write the parameter as: | |
1839 | ivrs_acpihid[00:14.5]=AMD0020:0 | |
1840 | ||
1841 | js= [HW,JOY] Analog joystick | |
1842 | See Documentation/input/joydev/joystick.rst. | |
1843 | ||
1844 | nokaslr [KNL] | |
1845 | When CONFIG_RANDOMIZE_BASE is set, this disables | |
1846 | kernel and module base offset ASLR (Address Space | |
1847 | Layout Randomization). | |
1848 | ||
1849 | kasan_multi_shot | |
1850 | [KNL] Enforce KASAN (Kernel Address Sanitizer) to print | |
1851 | report on every invalid memory access. Without this | |
1852 | parameter KASAN will print report only for the first | |
1853 | invalid access. | |
1854 | ||
1855 | keepinitrd [HW,ARM] | |
1856 | ||
1857 | kernelcore= [KNL,X86,IA-64,PPC] | |
1858 | Format: nn[KMGTPE] | nn% | "mirror" | |
1859 | This parameter specifies the amount of memory usable by | |
1860 | the kernel for non-movable allocations. The requested | |
1861 | amount is spread evenly throughout all nodes in the | |
1862 | system as ZONE_NORMAL. The remaining memory is used for | |
1863 | movable memory in its own zone, ZONE_MOVABLE. In the | |
1864 | event, a node is too small to have both ZONE_NORMAL and | |
1865 | ZONE_MOVABLE, kernelcore memory will take priority and | |
1866 | other nodes will have a larger ZONE_MOVABLE. | |
1867 | ||
1868 | ZONE_MOVABLE is used for the allocation of pages that | |
1869 | may be reclaimed or moved by the page migration | |
1870 | subsystem. Note that allocations like PTEs-from-HighMem | |
1871 | still use the HighMem zone if it exists, and the Normal | |
1872 | zone if it does not. | |
1873 | ||
1874 | It is possible to specify the exact amount of memory in | |
1875 | the form of "nn[KMGTPE]", a percentage of total system | |
1876 | memory in the form of "nn%", or "mirror". If "mirror" | |
1877 | option is specified, mirrored (reliable) memory is used | |
1878 | for non-movable allocations and remaining memory is used | |
1879 | for Movable pages. "nn[KMGTPE]", "nn%", and "mirror" | |
1880 | are exclusive, so you cannot specify multiple forms. | |
1881 | ||
1882 | kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. | |
1883 | Format: <Controller#>[,poll interval] | |
1884 | The controller # is the number of the ehci usb debug | |
1885 | port as it is probed via PCI. The poll interval is | |
1886 | optional and is the number seconds in between | |
1887 | each poll cycle to the debug port in case you need | |
1888 | the functionality for interrupting the kernel with | |
1889 | gdb or control-c on the dbgp connection. When | |
1890 | not using this parameter you use sysrq-g to break into | |
1891 | the kernel debugger. | |
1892 | ||
1893 | kgdboc= [KGDB,HW] kgdb over consoles. | |
1894 | Requires a tty driver that supports console polling, | |
1895 | or a supported polling keyboard driver (non-usb). | |
1896 | Serial only format: <serial_device>[,baud] | |
1897 | keyboard only format: kbd | |
1898 | keyboard and serial format: kbd,<serial_device>[,baud] | |
1899 | Optional Kernel mode setting: | |
1900 | kms, kbd format: kms,kbd | |
1901 | kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] | |
1902 | ||
1903 | kgdbwait [KGDB] Stop kernel execution and enter the | |
1904 | kernel debugger at the earliest opportunity. | |
1905 | ||
1906 | kmac= [MIPS] korina ethernet MAC address. | |
1907 | Configure the RouterBoard 532 series on-chip | |
1908 | Ethernet adapter MAC address. | |
1909 | ||
1910 | kmemleak= [KNL] Boot-time kmemleak enable/disable | |
1911 | Valid arguments: on, off | |
1912 | Default: on | |
1913 | Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, | |
1914 | the default is off. | |
1915 | ||
1916 | kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. | |
1917 | Default is 0 (don't ignore, but inject #GP) | |
1918 | ||
1919 | kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface. | |
1920 | Default is false (don't support). | |
1921 | ||
1922 | kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit | |
1923 | KVM MMU at runtime. | |
1924 | Default is 0 (off) | |
1925 | ||
1926 | kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. | |
1927 | Default is 1 (enabled) | |
1928 | ||
1929 | kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) | |
1930 | for all guests. | |
1931 | Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. | |
1932 | ||
1933 | kvm-arm.vgic_v3_group0_trap= | |
1934 | [KVM,ARM] Trap guest accesses to GICv3 group-0 | |
1935 | system registers | |
1936 | ||
1937 | kvm-arm.vgic_v3_group1_trap= | |
1938 | [KVM,ARM] Trap guest accesses to GICv3 group-1 | |
1939 | system registers | |
1940 | ||
1941 | kvm-arm.vgic_v3_common_trap= | |
1942 | [KVM,ARM] Trap guest accesses to GICv3 common | |
1943 | system registers | |
1944 | ||
1945 | kvm-arm.vgic_v4_enable= | |
1946 | [KVM,ARM] Allow use of GICv4 for direct injection of | |
1947 | LPIs. | |
1948 | ||
1949 | kvm-intel.ept= [KVM,Intel] Disable extended page tables | |
1950 | (virtualized MMU) support on capable Intel chips. | |
1951 | Default is 1 (enabled) | |
1952 | ||
1953 | kvm-intel.emulate_invalid_guest_state= | |
1954 | [KVM,Intel] Enable emulation of invalid guest states | |
1955 | Default is 0 (disabled) | |
1956 | ||
1957 | kvm-intel.flexpriority= | |
1958 | [KVM,Intel] Disable FlexPriority feature (TPR shadow). | |
1959 | Default is 1 (enabled) | |
1960 | ||
1961 | kvm-intel.nested= | |
1962 | [KVM,Intel] Enable VMX nesting (nVMX). | |
1963 | Default is 0 (disabled) | |
1964 | ||
1965 | kvm-intel.unrestricted_guest= | |
1966 | [KVM,Intel] Disable unrestricted guest feature | |
1967 | (virtualized real and unpaged mode) on capable | |
1968 | Intel chips. Default is 1 (enabled) | |
1969 | ||
1970 | kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification | |
1971 | feature (tagged TLBs) on capable Intel chips. | |
1972 | Default is 1 (enabled) | |
1973 | ||
1974 | l2cr= [PPC] | |
1975 | ||
1976 | l3cr= [PPC] | |
1977 | ||
1978 | lapic [X86-32,APIC] Enable the local APIC even if BIOS | |
1979 | disabled it. | |
1980 | ||
1981 | lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline | |
1982 | value for LAPIC timer one-shot implementation. Default | |
1983 | back to the programmable timer unit in the LAPIC. | |
1984 | ||
1985 | lapic_timer_c2_ok [X86,APIC] trust the local apic timer | |
1986 | in C2 power state. | |
1987 | ||
1988 | libata.dma= [LIBATA] DMA control | |
1989 | libata.dma=0 Disable all PATA and SATA DMA | |
1990 | libata.dma=1 PATA and SATA Disk DMA only | |
1991 | libata.dma=2 ATAPI (CDROM) DMA only | |
1992 | libata.dma=4 Compact Flash DMA only | |
1993 | Combinations also work, so libata.dma=3 enables DMA | |
1994 | for disks and CDROMs, but not CFs. | |
1995 | ||
1996 | libata.ignore_hpa= [LIBATA] Ignore HPA limit | |
1997 | libata.ignore_hpa=0 keep BIOS limits (default) | |
1998 | libata.ignore_hpa=1 ignore limits, using full disk | |
1999 | ||
2000 | libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume | |
2001 | when set. | |
2002 | Format: <int> | |
2003 | ||
2004 | libata.force= [LIBATA] Force configurations. The format is comma | |
2005 | separated list of "[ID:]VAL" where ID is | |
2006 | PORT[.DEVICE]. PORT and DEVICE are decimal numbers | |
2007 | matching port, link or device. Basically, it matches | |
2008 | the ATA ID string printed on console by libata. If | |
2009 | the whole ID part is omitted, the last PORT and DEVICE | |
2010 | values are used. If ID hasn't been specified yet, the | |
2011 | configuration applies to all ports, links and devices. | |
2012 | ||
2013 | If only DEVICE is omitted, the parameter applies to | |
2014 | the port and all links and devices behind it. DEVICE | |
2015 | number of 0 either selects the first device or the | |
2016 | first fan-out link behind PMP device. It does not | |
2017 | select the host link. DEVICE number of 15 selects the | |
2018 | host link and device attached to it. | |
2019 | ||
2020 | The VAL specifies the configuration to force. As long | |
2021 | as there's no ambiguity shortcut notation is allowed. | |
2022 | For example, both 1.5 and 1.5G would work for 1.5Gbps. | |
2023 | The following configurations can be forced. | |
2024 | ||
2025 | * Cable type: 40c, 80c, short40c, unk, ign or sata. | |
2026 | Any ID with matching PORT is used. | |
2027 | ||
2028 | * SATA link speed limit: 1.5Gbps or 3.0Gbps. | |
2029 | ||
2030 | * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. | |
2031 | udma[/][16,25,33,44,66,100,133] notation is also | |
2032 | allowed. | |
2033 | ||
2034 | * [no]ncq: Turn on or off NCQ. | |
2035 | ||
2036 | * [no]ncqtrim: Turn off queued DSM TRIM. | |
2037 | ||
2038 | * nohrst, nosrst, norst: suppress hard, soft | |
2039 | and both resets. | |
2040 | ||
2041 | * rstonce: only attempt one reset during | |
2042 | hot-unplug link recovery | |
2043 | ||
2044 | * dump_id: dump IDENTIFY data. | |
2045 | ||
2046 | * atapi_dmadir: Enable ATAPI DMADIR bridge support | |
2047 | ||
2048 | * disable: Disable this device. | |
2049 | ||
2050 | If there are multiple matching configurations changing | |
2051 | the same attribute, the last one is used. | |
2052 | ||
2053 | memblock=debug [KNL] Enable memblock debug messages. | |
2054 | ||
2055 | load_ramdisk= [RAM] List of ramdisks to load from floppy | |
2056 | See Documentation/blockdev/ramdisk.txt. | |
2057 | ||
2058 | lockd.nlm_grace_period=P [NFS] Assign grace period. | |
2059 | Format: <integer> | |
2060 | ||
2061 | lockd.nlm_tcpport=N [NFS] Assign TCP port. | |
2062 | Format: <integer> | |
2063 | ||
2064 | lockd.nlm_timeout=T [NFS] Assign timeout value. | |
2065 | Format: <integer> | |
2066 | ||
2067 | lockd.nlm_udpport=M [NFS] Assign UDP port. | |
2068 | Format: <integer> | |
2069 | ||
2070 | locktorture.nreaders_stress= [KNL] | |
2071 | Set the number of locking read-acquisition kthreads. | |
2072 | Defaults to being automatically set based on the | |
2073 | number of online CPUs. | |
2074 | ||
2075 | locktorture.nwriters_stress= [KNL] | |
2076 | Set the number of locking write-acquisition kthreads. | |
2077 | ||
2078 | locktorture.onoff_holdoff= [KNL] | |
2079 | Set time (s) after boot for CPU-hotplug testing. | |
2080 | ||
2081 | locktorture.onoff_interval= [KNL] | |
2082 | Set time (s) between CPU-hotplug operations, or | |
2083 | zero to disable CPU-hotplug testing. | |
2084 | ||
2085 | locktorture.shuffle_interval= [KNL] | |
2086 | Set task-shuffle interval (jiffies). Shuffling | |
2087 | tasks allows some CPUs to go into dyntick-idle | |
2088 | mode during the locktorture test. | |
2089 | ||
2090 | locktorture.shutdown_secs= [KNL] | |
2091 | Set time (s) after boot system shutdown. This | |
2092 | is useful for hands-off automated testing. | |
2093 | ||
2094 | locktorture.stat_interval= [KNL] | |
2095 | Time (s) between statistics printk()s. | |
2096 | ||
2097 | locktorture.stutter= [KNL] | |
2098 | Time (s) to stutter testing, for example, | |
2099 | specifying five seconds causes the test to run for | |
2100 | five seconds, wait for five seconds, and so on. | |
2101 | This tests the locking primitive's ability to | |
2102 | transition abruptly to and from idle. | |
2103 | ||
2104 | locktorture.torture_type= [KNL] | |
2105 | Specify the locking implementation to test. | |
2106 | ||
2107 | locktorture.verbose= [KNL] | |
2108 | Enable additional printk() statements. | |
2109 | ||
2110 | logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver | |
2111 | Format: <irq> | |
2112 | ||
2113 | loglevel= All Kernel Messages with a loglevel smaller than the | |
2114 | console loglevel will be printed to the console. It can | |
2115 | also be changed with klogd or other programs. The | |
2116 | loglevels are defined as follows: | |
2117 | ||
2118 | 0 (KERN_EMERG) system is unusable | |
2119 | 1 (KERN_ALERT) action must be taken immediately | |
2120 | 2 (KERN_CRIT) critical conditions | |
2121 | 3 (KERN_ERR) error conditions | |
2122 | 4 (KERN_WARNING) warning conditions | |
2123 | 5 (KERN_NOTICE) normal but significant condition | |
2124 | 6 (KERN_INFO) informational | |
2125 | 7 (KERN_DEBUG) debug-level messages | |
2126 | ||
2127 | log_buf_len=n[KMG] Sets the size of the printk ring buffer, | |
2128 | in bytes. n must be a power of two and greater | |
2129 | than the minimal size. The minimal size is defined | |
2130 | by LOG_BUF_SHIFT kernel config parameter. There is | |
2131 | also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter | |
2132 | that allows to increase the default size depending on | |
2133 | the number of CPUs. See init/Kconfig for more details. | |
2134 | ||
2135 | logo.nologo [FB] Disables display of the built-in Linux logo. | |
2136 | This may be used to provide more screen space for | |
2137 | kernel log messages and is useful when debugging | |
2138 | kernel boot problems. | |
2139 | ||
2140 | lp=0 [LP] Specify parallel ports to use, e.g, | |
2141 | lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses | |
2142 | lp=reset first parallel port). 'lp=0' disables the | |
2143 | lp=auto printer driver. 'lp=reset' (which can be | |
2144 | specified in addition to the ports) causes | |
2145 | attached printers to be reset. Using | |
2146 | lp=port1,port2,... specifies the parallel ports | |
2147 | to associate lp devices with, starting with | |
2148 | lp0. A port specification may be 'none' to skip | |
2149 | that lp device, or a parport name such as | |
2150 | 'parport0'. Specifying 'lp=auto' instead of a | |
2151 | port specification list means that device IDs | |
2152 | from each port should be examined, to see if | |
2153 | an IEEE 1284-compliant printer is attached; if | |
2154 | so, the driver will manage that printer. | |
2155 | See also header of drivers/char/lp.c. | |
2156 | ||
2157 | lpj=n [KNL] | |
2158 | Sets loops_per_jiffy to given constant, thus avoiding | |
2159 | time-consuming boot-time autodetection (up to 250 ms per | |
2160 | CPU). 0 enables autodetection (default). To determine | |
2161 | the correct value for your kernel, boot with normal | |
2162 | autodetection and see what value is printed. Note that | |
2163 | on SMP systems the preset will be applied to all CPUs, | |
2164 | which is likely to cause problems if your CPUs need | |
2165 | significantly divergent settings. An incorrect value | |
2166 | will cause delays in the kernel to be wrong, leading to | |
2167 | unpredictable I/O errors and other breakage. Although | |
2168 | unlikely, in the extreme case this might damage your | |
2169 | hardware. | |
2170 | ||
2171 | ltpc= [NET] | |
2172 | Format: <io>,<irq>,<dma> | |
2173 | ||
2174 | machvec= [IA-64] Force the use of a particular machine-vector | |
2175 | (machvec) in a generic kernel. | |
2176 | Example: machvec=hpzx1_swiotlb | |
2177 | ||
2178 | machtype= [Loongson] Share the same kernel image file between different | |
2179 | yeeloong laptop. | |
2180 | Example: machtype=lemote-yeeloong-2f-7inch | |
2181 | ||
2182 | max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater | |
2183 | than or equal to this physical address is ignored. | |
2184 | ||
2185 | maxcpus= [SMP] Maximum number of processors that an SMP kernel | |
2186 | will bring up during bootup. maxcpus=n : n >= 0 limits | |
2187 | the kernel to bring up 'n' processors. Surely after | |
2188 | bootup you can bring up the other plugged cpu by executing | |
2189 | "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus | |
2190 | only takes effect during system bootup. | |
2191 | While n=0 is a special case, it is equivalent to "nosmp", | |
2192 | which also disables the IO APIC. | |
2193 | ||
2194 | max_loop= [LOOP] The number of loop block devices that get | |
2195 | (loop.max_loop) unconditionally pre-created at init time. The default | |
2196 | number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead | |
2197 | of statically allocating a predefined number, loop | |
2198 | devices can be requested on-demand with the | |
2199 | /dev/loop-control interface. | |
2200 | ||
2201 | mce [X86-32] Machine Check Exception | |
2202 | ||
2203 | mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt | |
2204 | ||
2205 | md= [HW] RAID subsystems devices and level | |
2206 | See Documentation/admin-guide/md.rst. | |
2207 | ||
2208 | mdacon= [MDA] | |
2209 | Format: <first>,<last> | |
2210 | Specifies range of consoles to be captured by the MDA. | |
2211 | ||
2212 | mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory | |
2213 | Amount of memory to be used when the kernel is not able | |
2214 | to see the whole system memory or for test. | |
2215 | [X86] Work as limiting max address. Use together | |
2216 | with memmap= to avoid physical address space collisions. | |
2217 | Without memmap= PCI devices could be placed at addresses | |
2218 | belonging to unused RAM. | |
2219 | ||
2220 | mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel | |
2221 | memory. | |
2222 | ||
2223 | memchunk=nn[KMG] | |
2224 | [KNL,SH] Allow user to override the default size for | |
2225 | per-device physically contiguous DMA buffers. | |
2226 | ||
2227 | memhp_default_state=online/offline | |
2228 | [KNL] Set the initial state for the memory hotplug | |
2229 | onlining policy. If not specified, the default value is | |
2230 | set according to the | |
2231 | CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config | |
2232 | option. | |
2233 | See Documentation/memory-hotplug.txt. | |
2234 | ||
2235 | memmap=exactmap [KNL,X86] Enable setting of an exact | |
2236 | E820 memory map, as specified by the user. | |
2237 | Such memmap=exactmap lines can be constructed based on | |
2238 | BIOS output or other requirements. See the memmap=nn@ss | |
2239 | option description. | |
2240 | ||
2241 | memmap=nn[KMG]@ss[KMG] | |
2242 | [KNL] Force usage of a specific region of memory. | |
2243 | Region of memory to be used is from ss to ss+nn. | |
2244 | If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG], | |
2245 | which limits max address to nn[KMG]. | |
2246 | Multiple different regions can be specified, | |
2247 | comma delimited. | |
2248 | Example: | |
2249 | memmap=100M@2G,100M#3G,1G!1024G | |
2250 | ||
2251 | memmap=nn[KMG]#ss[KMG] | |
2252 | [KNL,ACPI] Mark specific memory as ACPI data. | |
2253 | Region of memory to be marked is from ss to ss+nn. | |
2254 | ||
2255 | memmap=nn[KMG]$ss[KMG] | |
2256 | [KNL,ACPI] Mark specific memory as reserved. | |
2257 | Region of memory to be reserved is from ss to ss+nn. | |
2258 | Example: Exclude memory from 0x18690000-0x1869ffff | |
2259 | memmap=64K$0x18690000 | |
2260 | or | |
2261 | memmap=0x10000$0x18690000 | |
2262 | Some bootloaders may need an escape character before '$', | |
2263 | like Grub2, otherwise '$' and the following number | |
2264 | will be eaten. | |
2265 | ||
2266 | memmap=nn[KMG]!ss[KMG] | |
2267 | [KNL,X86] Mark specific memory as protected. | |
2268 | Region of memory to be used, from ss to ss+nn. | |
2269 | The memory region may be marked as e820 type 12 (0xc) | |
2270 | and is NVDIMM or ADR memory. | |
2271 | ||
2272 | memmap=<size>%<offset>-<oldtype>+<newtype> | |
2273 | [KNL,ACPI] Convert memory within the specified region | |
2274 | from <oldtype> to <newtype>. If "-<oldtype>" is left | |
2275 | out, the whole region will be marked as <newtype>, | |
2276 | even if previously unavailable. If "+<newtype>" is left | |
2277 | out, matching memory will be removed. Types are | |
2278 | specified as e820 types, e.g., 1 = RAM, 2 = reserved, | |
2279 | 3 = ACPI, 12 = PRAM. | |
2280 | ||
2281 | memory_corruption_check=0/1 [X86] | |
2282 | Some BIOSes seem to corrupt the first 64k of | |
2283 | memory when doing things like suspend/resume. | |
2284 | Setting this option will scan the memory | |
2285 | looking for corruption. Enabling this will | |
2286 | both detect corruption and prevent the kernel | |
2287 | from using the memory being corrupted. | |
2288 | However, its intended as a diagnostic tool; if | |
2289 | repeatable BIOS-originated corruption always | |
2290 | affects the same memory, you can use memmap= | |
2291 | to prevent the kernel from using that memory. | |
2292 | ||
2293 | memory_corruption_check_size=size [X86] | |
2294 | By default it checks for corruption in the low | |
2295 | 64k, making this memory unavailable for normal | |
2296 | use. Use this parameter to scan for | |
2297 | corruption in more or less memory. | |
2298 | ||
2299 | memory_corruption_check_period=seconds [X86] | |
2300 | By default it checks for corruption every 60 | |
2301 | seconds. Use this parameter to check at some | |
2302 | other rate. 0 disables periodic checking. | |
2303 | ||
2304 | memtest= [KNL,X86,ARM] Enable memtest | |
2305 | Format: <integer> | |
2306 | default : 0 <disable> | |
2307 | Specifies the number of memtest passes to be | |
2308 | performed. Each pass selects another test | |
2309 | pattern from a given set of patterns. Memtest | |
2310 | fills the memory with this pattern, validates | |
2311 | memory contents and reserves bad memory | |
2312 | regions that are detected. | |
2313 | ||
2314 | mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control | |
2315 | Valid arguments: on, off | |
2316 | Default (depends on kernel configuration option): | |
2317 | on (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y) | |
2318 | off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n) | |
2319 | mem_encrypt=on: Activate SME | |
2320 | mem_encrypt=off: Do not activate SME | |
2321 | ||
2322 | Refer to Documentation/x86/amd-memory-encryption.txt | |
2323 | for details on when memory encryption can be activated. | |
2324 | ||
2325 | mem_sleep_default= [SUSPEND] Default system suspend mode: | |
2326 | s2idle - Suspend-To-Idle | |
2327 | shallow - Power-On Suspend or equivalent (if supported) | |
2328 | deep - Suspend-To-RAM or equivalent (if supported) | |
2329 | See Documentation/admin-guide/pm/sleep-states.rst. | |
2330 | ||
2331 | meye.*= [HW] Set MotionEye Camera parameters | |
2332 | See Documentation/media/v4l-drivers/meye.rst. | |
2333 | ||
2334 | mfgpt_irq= [IA-32] Specify the IRQ to use for the | |
2335 | Multi-Function General Purpose Timers on AMD Geode | |
2336 | platforms. | |
2337 | ||
2338 | mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when | |
2339 | the BIOS has incorrectly applied a workaround. TinyBIOS | |
2340 | version 0.98 is known to be affected, 0.99 fixes the | |
2341 | problem by letting the user disable the workaround. | |
2342 | ||
2343 | mga= [HW,DRM] | |
2344 | ||
2345 | min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this | |
2346 | physical address is ignored. | |
2347 | ||
2348 | mini2440= [ARM,HW,KNL] | |
2349 | Format:[0..2][b][c][t] | |
2350 | Default: "0tb" | |
2351 | MINI2440 configuration specification: | |
2352 | 0 - The attached screen is the 3.5" TFT | |
2353 | 1 - The attached screen is the 7" TFT | |
2354 | 2 - The VGA Shield is attached (1024x768) | |
2355 | Leaving out the screen size parameter will not load | |
2356 | the TFT driver, and the framebuffer will be left | |
2357 | unconfigured. | |
2358 | b - Enable backlight. The TFT backlight pin will be | |
2359 | linked to the kernel VESA blanking code and a GPIO | |
2360 | LED. This parameter is not necessary when using the | |
2361 | VGA shield. | |
2362 | c - Enable the s3c camera interface. | |
2363 | t - Reserved for enabling touchscreen support. The | |
2364 | touchscreen support is not enabled in the mainstream | |
2365 | kernel as of 2.6.30, a preliminary port can be found | |
2366 | in the "bleeding edge" mini2440 support kernel at | |
2367 | http://repo.or.cz/w/linux-2.6/mini2440.git | |
2368 | ||
2369 | mminit_loglevel= | |
2370 | [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this | |
2371 | parameter allows control of the logging verbosity for | |
2372 | the additional memory initialisation checks. A value | |
2373 | of 0 disables mminit logging and a level of 4 will | |
2374 | log everything. Information is printed at KERN_DEBUG | |
2375 | so loglevel=8 may also need to be specified. | |
2376 | ||
2377 | module.sig_enforce | |
2378 | [KNL] When CONFIG_MODULE_SIG is set, this means that | |
2379 | modules without (valid) signatures will fail to load. | |
2380 | Note that if CONFIG_MODULE_SIG_FORCE is set, that | |
2381 | is always true, so this option does nothing. | |
2382 | ||
2383 | module_blacklist= [KNL] Do not load a comma-separated list of | |
2384 | modules. Useful for debugging problem modules. | |
2385 | ||
2386 | mousedev.tap_time= | |
2387 | [MOUSE] Maximum time between finger touching and | |
2388 | leaving touchpad surface for touch to be considered | |
2389 | a tap and be reported as a left button click (for | |
2390 | touchpads working in absolute mode only). | |
2391 | Format: <msecs> | |
2392 | mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices | |
2393 | reporting absolute coordinates, such as tablets | |
2394 | mousedev.yres= [MOUSE] Vertical screen resolution, used for devices | |
2395 | reporting absolute coordinates, such as tablets | |
2396 | ||
2397 | movablecore= [KNL,X86,IA-64,PPC] | |
2398 | Format: nn[KMGTPE] | nn% | |
2399 | This parameter is the complement to kernelcore=, it | |
2400 | specifies the amount of memory used for migratable | |
2401 | allocations. If both kernelcore and movablecore is | |
2402 | specified, then kernelcore will be at *least* the | |
2403 | specified value but may be more. If movablecore on its | |
2404 | own is specified, the administrator must be careful | |
2405 | that the amount of memory usable for all allocations | |
2406 | is not too small. | |
2407 | ||
2408 | movable_node [KNL] Boot-time switch to make hotplugable memory | |
2409 | NUMA nodes to be movable. This means that the memory | |
2410 | of such nodes will be usable only for movable | |
2411 | allocations which rules out almost all kernel | |
2412 | allocations. Use with caution! | |
2413 | ||
2414 | MTD_Partition= [MTD] | |
2415 | Format: <name>,<region-number>,<size>,<offset> | |
2416 | ||
2417 | MTD_Region= [MTD] Format: | |
2418 | <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] | |
2419 | ||
2420 | mtdparts= [MTD] | |
2421 | See drivers/mtd/cmdlinepart.c. | |
2422 | ||
2423 | multitce=off [PPC] This parameter disables the use of the pSeries | |
2424 | firmware feature for updating multiple TCE entries | |
2425 | at a time. | |
2426 | ||
2427 | onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration | |
2428 | ||
2429 | Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] | |
2430 | ||
2431 | boundary - index of last SLC block on Flex-OneNAND. | |
2432 | The remaining blocks are configured as MLC blocks. | |
2433 | lock - Configure if Flex-OneNAND boundary should be locked. | |
2434 | Once locked, the boundary cannot be changed. | |
2435 | 1 indicates lock status, 0 indicates unlock status. | |
2436 | ||
2437 | mtdset= [ARM] | |
2438 | ARM/S3C2412 JIVE boot control | |
2439 | ||
2440 | See arch/arm/mach-s3c2412/mach-jive.c | |
2441 | ||
2442 | mtouchusb.raw_coordinates= | |
2443 | [HW] Make the MicroTouch USB driver use raw coordinates | |
2444 | ('y', default) or cooked coordinates ('n') | |
2445 | ||
2446 | mtrr_chunk_size=nn[KMG] [X86] | |
2447 | used for mtrr cleanup. It is largest continuous chunk | |
2448 | that could hold holes aka. UC entries. | |
2449 | ||
2450 | mtrr_gran_size=nn[KMG] [X86] | |
2451 | Used for mtrr cleanup. It is granularity of mtrr block. | |
2452 | Default is 1. | |
2453 | Large value could prevent small alignment from | |
2454 | using up MTRRs. | |
2455 | ||
2456 | mtrr_spare_reg_nr=n [X86] | |
2457 | Format: <integer> | |
2458 | Range: 0,7 : spare reg number | |
2459 | Default : 1 | |
2460 | Used for mtrr cleanup. It is spare mtrr entries number. | |
2461 | Set to 2 or more if your graphical card needs more. | |
2462 | ||
2463 | n2= [NET] SDL Inc. RISCom/N2 synchronous serial card | |
2464 | ||
2465 | netdev= [NET] Network devices parameters | |
2466 | Format: <irq>,<io>,<mem_start>,<mem_end>,<name> | |
2467 | Note that mem_start is often overloaded to mean | |
2468 | something different and driver-specific. | |
2469 | This usage is only documented in each driver source | |
2470 | file if at all. | |
2471 | ||
2472 | nf_conntrack.acct= | |
2473 | [NETFILTER] Enable connection tracking flow accounting | |
2474 | 0 to disable accounting | |
2475 | 1 to enable accounting | |
2476 | Default value is 0. | |
2477 | ||
2478 | nfsaddrs= [NFS] Deprecated. Use ip= instead. | |
2479 | See Documentation/filesystems/nfs/nfsroot.txt. | |
2480 | ||
2481 | nfsroot= [NFS] nfs root filesystem for disk-less boxes. | |
2482 | See Documentation/filesystems/nfs/nfsroot.txt. | |
2483 | ||
2484 | nfsrootdebug [NFS] enable nfsroot debugging messages. | |
2485 | See Documentation/filesystems/nfs/nfsroot.txt. | |
2486 | ||
2487 | nfs.callback_nr_threads= | |
2488 | [NFSv4] set the total number of threads that the | |
2489 | NFS client will assign to service NFSv4 callback | |
2490 | requests. | |
2491 | ||
2492 | nfs.callback_tcpport= | |
2493 | [NFS] set the TCP port on which the NFSv4 callback | |
2494 | channel should listen. | |
2495 | ||
2496 | nfs.cache_getent= | |
2497 | [NFS] sets the pathname to the program which is used | |
2498 | to update the NFS client cache entries. | |
2499 | ||
2500 | nfs.cache_getent_timeout= | |
2501 | [NFS] sets the timeout after which an attempt to | |
2502 | update a cache entry is deemed to have failed. | |
2503 | ||
2504 | nfs.idmap_cache_timeout= | |
2505 | [NFS] set the maximum lifetime for idmapper cache | |
2506 | entries. | |
2507 | ||
2508 | nfs.enable_ino64= | |
2509 | [NFS] enable 64-bit inode numbers. | |
2510 | If zero, the NFS client will fake up a 32-bit inode | |
2511 | number for the readdir() and stat() syscalls instead | |
2512 | of returning the full 64-bit number. | |
2513 | The default is to return 64-bit inode numbers. | |
2514 | ||
2515 | nfs.max_session_cb_slots= | |
2516 | [NFSv4.1] Sets the maximum number of session | |
2517 | slots the client will assign to the callback | |
2518 | channel. This determines the maximum number of | |
2519 | callbacks the client will process in parallel for | |
2520 | a particular server. | |
2521 | ||
2522 | nfs.max_session_slots= | |
2523 | [NFSv4.1] Sets the maximum number of session slots | |
2524 | the client will attempt to negotiate with the server. | |
2525 | This limits the number of simultaneous RPC requests | |
2526 | that the client can send to the NFSv4.1 server. | |
2527 | Note that there is little point in setting this | |
2528 | value higher than the max_tcp_slot_table_limit. | |
2529 | ||
2530 | nfs.nfs4_disable_idmapping= | |
2531 | [NFSv4] When set to the default of '1', this option | |
2532 | ensures that both the RPC level authentication | |
2533 | scheme and the NFS level operations agree to use | |
2534 | numeric uids/gids if the mount is using the | |
2535 | 'sec=sys' security flavour. In effect it is | |
2536 | disabling idmapping, which can make migration from | |
2537 | legacy NFSv2/v3 systems to NFSv4 easier. | |
2538 | Servers that do not support this mode of operation | |
2539 | will be autodetected by the client, and it will fall | |
2540 | back to using the idmapper. | |
2541 | To turn off this behaviour, set the value to '0'. | |
2542 | nfs.nfs4_unique_id= | |
2543 | [NFS4] Specify an additional fixed unique ident- | |
2544 | ification string that NFSv4 clients can insert into | |
2545 | their nfs_client_id4 string. This is typically a | |
2546 | UUID that is generated at system install time. | |
2547 | ||
2548 | nfs.send_implementation_id = | |
2549 | [NFSv4.1] Send client implementation identification | |
2550 | information in exchange_id requests. | |
2551 | If zero, no implementation identification information | |
2552 | will be sent. | |
2553 | The default is to send the implementation identification | |
2554 | information. | |
2555 | ||
2556 | nfs.recover_lost_locks = | |
2557 | [NFSv4] Attempt to recover locks that were lost due | |
2558 | to a lease timeout on the server. Please note that | |
2559 | doing this risks data corruption, since there are | |
2560 | no guarantees that the file will remain unchanged | |
2561 | after the locks are lost. | |
2562 | If you want to enable the kernel legacy behaviour of | |
2563 | attempting to recover these locks, then set this | |
2564 | parameter to '1'. | |
2565 | The default parameter value of '0' causes the kernel | |
2566 | not to attempt recovery of lost locks. | |
2567 | ||
2568 | nfs4.layoutstats_timer = | |
2569 | [NFSv4.2] Change the rate at which the kernel sends | |
2570 | layoutstats to the pNFS metadata server. | |
2571 | ||
2572 | Setting this to value to 0 causes the kernel to use | |
2573 | whatever value is the default set by the layout | |
2574 | driver. A non-zero value sets the minimum interval | |
2575 | in seconds between layoutstats transmissions. | |
2576 | ||
2577 | nfsd.nfs4_disable_idmapping= | |
2578 | [NFSv4] When set to the default of '1', the NFSv4 | |
2579 | server will return only numeric uids and gids to | |
2580 | clients using auth_sys, and will accept numeric uids | |
2581 | and gids from such clients. This is intended to ease | |
2582 | migration from NFSv2/v3. | |
2583 | ||
2584 | nmi_debug= [KNL,SH] Specify one or more actions to take | |
2585 | when a NMI is triggered. | |
2586 | Format: [state][,regs][,debounce][,die] | |
2587 | ||
2588 | nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels | |
2589 | Format: [panic,][nopanic,][num] | |
2590 | Valid num: 0 or 1 | |
2591 | 0 - turn hardlockup detector in nmi_watchdog off | |
2592 | 1 - turn hardlockup detector in nmi_watchdog on | |
2593 | When panic is specified, panic when an NMI watchdog | |
2594 | timeout occurs (or 'nopanic' to override the opposite | |
2595 | default). To disable both hard and soft lockup detectors, | |
2596 | please see 'nowatchdog'. | |
2597 | This is useful when you use a panic=... timeout and | |
2598 | need the box quickly up again. | |
2599 | ||
2600 | These settings can be accessed at runtime via | |
2601 | the nmi_watchdog and hardlockup_panic sysctls. | |
2602 | ||
2603 | netpoll.carrier_timeout= | |
2604 | [NET] Specifies amount of time (in seconds) that | |
2605 | netpoll should wait for a carrier. By default netpoll | |
2606 | waits 4 seconds. | |
2607 | ||
2608 | no387 [BUGS=X86-32] Tells the kernel to use the 387 maths | |
2609 | emulation library even if a 387 maths coprocessor | |
2610 | is present. | |
2611 | ||
2612 | no5lvl [X86-64] Disable 5-level paging mode. Forces | |
2613 | kernel to use 4-level paging instead. | |
2614 | ||
2615 | no_console_suspend | |
2616 | [HW] Never suspend the console | |
2617 | Disable suspending of consoles during suspend and | |
2618 | hibernate operations. Once disabled, debugging | |
2619 | messages can reach various consoles while the rest | |
2620 | of the system is being put to sleep (ie, while | |
2621 | debugging driver suspend/resume hooks). This may | |
2622 | not work reliably with all consoles, but is known | |
2623 | to work with serial and VGA consoles. | |
2624 | To facilitate more flexible debugging, we also add | |
2625 | console_suspend, a printk module parameter to control | |
2626 | it. Users could use console_suspend (usually | |
2627 | /sys/module/printk/parameters/console_suspend) to | |
2628 | turn on/off it dynamically. | |
2629 | ||
2630 | noaliencache [MM, NUMA, SLAB] Disables the allocation of alien | |
2631 | caches in the slab allocator. Saves per-node memory, | |
2632 | but will impact performance. | |
2633 | ||
2634 | noalign [KNL,ARM] | |
2635 | ||
2636 | noaltinstr [S390] Disables alternative instructions patching | |
2637 | (CPU alternatives feature). | |
2638 | ||
2639 | noapic [SMP,APIC] Tells the kernel to not make use of any | |
2640 | IOAPICs that may be present in the system. | |
2641 | ||
2642 | noautogroup Disable scheduler automatic task group creation. | |
2643 | ||
2644 | nobats [PPC] Do not use BATs for mapping kernel lowmem | |
2645 | on "Classic" PPC cores. | |
2646 | ||
2647 | nocache [ARM] | |
2648 | ||
2649 | noclflush [BUGS=X86] Don't use the CLFLUSH instruction | |
2650 | ||
2651 | nodelayacct [KNL] Disable per-task delay accounting | |
2652 | ||
2653 | nodsp [SH] Disable hardware DSP at boot time. | |
2654 | ||
2655 | noefi Disable EFI runtime services support. | |
2656 | ||
2657 | noexec [IA-64] | |
2658 | ||
2659 | noexec [X86] | |
2660 | On X86-32 available only on PAE configured kernels. | |
2661 | noexec=on: enable non-executable mappings (default) | |
2662 | noexec=off: disable non-executable mappings | |
2663 | ||
2664 | nosmap [X86] | |
2665 | Disable SMAP (Supervisor Mode Access Prevention) | |
2666 | even if it is supported by processor. | |
2667 | ||
2668 | nosmep [X86] | |
2669 | Disable SMEP (Supervisor Mode Execution Prevention) | |
2670 | even if it is supported by processor. | |
2671 | ||
2672 | noexec32 [X86-64] | |
2673 | This affects only 32-bit executables. | |
2674 | noexec32=on: enable non-executable mappings (default) | |
2675 | read doesn't imply executable mappings | |
2676 | noexec32=off: disable non-executable mappings | |
2677 | read implies executable mappings | |
2678 | ||
2679 | nofpu [MIPS,SH] Disable hardware FPU at boot time. | |
2680 | ||
2681 | nofxsr [BUGS=X86-32] Disables x86 floating point extended | |
2682 | register save and restore. The kernel will only save | |
2683 | legacy floating-point registers on task switch. | |
2684 | ||
2685 | nohugeiomap [KNL,x86] Disable kernel huge I/O mappings. | |
2686 | ||
2687 | nosmt [KNL,S390] Disable symmetric multithreading (SMT). | |
2688 | Equivalent to smt=1. | |
2689 | ||
2690 | nospectre_v2 [X86] Disable all mitigations for the Spectre variant 2 | |
2691 | (indirect branch prediction) vulnerability. System may | |
2692 | allow data leaks with this option, which is equivalent | |
2693 | to spectre_v2=off. | |
2694 | ||
2695 | nospec_store_bypass_disable | |
2696 | [HW] Disable all mitigations for the Speculative Store Bypass vulnerability | |
2697 | ||
2698 | noxsave [BUGS=X86] Disables x86 extended register state save | |
2699 | and restore using xsave. The kernel will fallback to | |
2700 | enabling legacy floating-point and sse state. | |
2701 | ||
2702 | noxsaveopt [X86] Disables xsaveopt used in saving x86 extended | |
2703 | register states. The kernel will fall back to use | |
2704 | xsave to save the states. By using this parameter, | |
2705 | performance of saving the states is degraded because | |
2706 | xsave doesn't support modified optimization while | |
2707 | xsaveopt supports it on xsaveopt enabled systems. | |
2708 | ||
2709 | noxsaves [X86] Disables xsaves and xrstors used in saving and | |
2710 | restoring x86 extended register state in compacted | |
2711 | form of xsave area. The kernel will fall back to use | |
2712 | xsaveopt and xrstor to save and restore the states | |
2713 | in standard form of xsave area. By using this | |
2714 | parameter, xsave area per process might occupy more | |
2715 | memory on xsaves enabled systems. | |
2716 | ||
2717 | nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or | |
2718 | wfi(ARM) instruction doesn't work correctly and not to | |
2719 | use it. This is also useful when using JTAG debugger. | |
2720 | ||
2721 | no_file_caps Tells the kernel not to honor file capabilities. The | |
2722 | only way then for a file to be executed with privilege | |
2723 | is to be setuid root or executed by root. | |
2724 | ||
2725 | nohalt [IA-64] Tells the kernel not to use the power saving | |
2726 | function PAL_HALT_LIGHT when idle. This increases | |
2727 | power-consumption. On the positive side, it reduces | |
2728 | interrupt wake-up latency, which may improve performance | |
2729 | in certain environments such as networked servers or | |
2730 | real-time systems. | |
2731 | ||
2732 | nohibernate [HIBERNATION] Disable hibernation and resume. | |
2733 | ||
2734 | nohz= [KNL] Boottime enable/disable dynamic ticks | |
2735 | Valid arguments: on, off | |
2736 | Default: on | |
2737 | ||
2738 | nohz_full= [KNL,BOOT,SMP,ISOL] | |
2739 | The argument is a cpu list, as described above. | |
2740 | In kernels built with CONFIG_NO_HZ_FULL=y, set | |
2741 | the specified list of CPUs whose tick will be stopped | |
2742 | whenever possible. The boot CPU will be forced outside | |
2743 | the range to maintain the timekeeping. Any CPUs | |
2744 | in this list will have their RCU callbacks offloaded, | |
2745 | just as if they had also been called out in the | |
2746 | rcu_nocbs= boot parameter. | |
2747 | ||
2748 | noiotrap [SH] Disables trapped I/O port accesses. | |
2749 | ||
2750 | noirqdebug [X86-32] Disables the code which attempts to detect and | |
2751 | disable unhandled interrupt sources. | |
2752 | ||
2753 | no_timer_check [X86,APIC] Disables the code which tests for | |
2754 | broken timer IRQ sources. | |
2755 | ||
2756 | noisapnp [ISAPNP] Disables ISA PnP code. | |
2757 | ||
2758 | noinitrd [RAM] Tells the kernel not to load any configured | |
2759 | initial RAM disk. | |
2760 | ||
2761 | nointremap [X86-64, Intel-IOMMU] Do not enable interrupt | |
2762 | remapping. | |
2763 | [Deprecated - use intremap=off] | |
2764 | ||
2765 | nointroute [IA-64] | |
2766 | ||
2767 | noinvpcid [X86] Disable the INVPCID cpu feature. | |
2768 | ||
2769 | nojitter [IA-64] Disables jitter checking for ITC timers. | |
2770 | ||
2771 | no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver | |
2772 | ||
2773 | no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page | |
2774 | fault handling. | |
2775 | ||
2776 | no-vmw-sched-clock | |
2777 | [X86,PV_OPS] Disable paravirtualized VMware scheduler | |
2778 | clock and use the default one. | |
2779 | ||
2780 | no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting. | |
2781 | steal time is computed, but won't influence scheduler | |
2782 | behaviour | |
2783 | ||
2784 | nolapic [X86-32,APIC] Do not enable or use the local APIC. | |
2785 | ||
2786 | nolapic_timer [X86-32,APIC] Do not use the local APIC timer. | |
2787 | ||
2788 | noltlbs [PPC] Do not use large page/tlb entries for kernel | |
2789 | lowmem mapping on PPC40x and PPC8xx | |
2790 | ||
2791 | nomca [IA-64] Disable machine check abort handling | |
2792 | ||
2793 | nomce [X86-32] Disable Machine Check Exception | |
2794 | ||
2795 | nomfgpt [X86-32] Disable Multi-Function General Purpose | |
2796 | Timer usage (for AMD Geode machines). | |
2797 | ||
2798 | nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to | |
2799 | shutdown the other cpus. Instead use the REBOOT_VECTOR | |
2800 | irq. | |
2801 | ||
2802 | nomodule Disable module load | |
2803 | ||
2804 | nopat [X86] Disable PAT (page attribute table extension of | |
2805 | pagetables) support. | |
2806 | ||
2807 | nopcid [X86-64] Disable the PCID cpu feature. | |
2808 | ||
2809 | norandmaps Don't use address space randomization. Equivalent to | |
2810 | echo 0 > /proc/sys/kernel/randomize_va_space | |
2811 | ||
2812 | noreplace-smp [X86-32,SMP] Don't replace SMP instructions | |
2813 | with UP alternatives | |
2814 | ||
2815 | nordrand [X86] Disable kernel use of the RDRAND and | |
2816 | RDSEED instructions even if they are supported | |
2817 | by the processor. RDRAND and RDSEED are still | |
2818 | available to user space applications. | |
2819 | ||
2820 | noresume [SWSUSP] Disables resume and restores original swap | |
2821 | space. | |
2822 | ||
2823 | no-scroll [VGA] Disables scrollback. | |
2824 | This is required for the Braillex ib80-piezo Braille | |
2825 | reader made by F.H. Papenmeier (Germany). | |
2826 | ||
2827 | nosbagart [IA-64] | |
2828 | ||
2829 | nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. | |
2830 | ||
2831 | nosmp [SMP] Tells an SMP kernel to act as a UP kernel, | |
2832 | and disable the IO APIC. legacy for "maxcpus=0". | |
2833 | ||
2834 | nosoftlockup [KNL] Disable the soft-lockup detector. | |
2835 | ||
2836 | nosync [HW,M68K] Disables sync negotiation for all devices. | |
2837 | ||
2838 | notsc [BUGS=X86-32] Disable Time Stamp Counter | |
2839 | ||
2840 | nowatchdog [KNL] Disable both lockup detectors, i.e. | |
2841 | soft-lockup and NMI watchdog (hard-lockup). | |
2842 | ||
2843 | nowb [ARM] | |
2844 | ||
2845 | nox2apic [X86-64,APIC] Do not enable x2APIC mode. | |
2846 | ||
2847 | cpu0_hotplug [X86] Turn on CPU0 hotplug feature when | |
2848 | CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. | |
2849 | Some features depend on CPU0. Known dependencies are: | |
2850 | 1. Resume from suspend/hibernate depends on CPU0. | |
2851 | Suspend/hibernate will fail if CPU0 is offline and you | |
2852 | need to online CPU0 before suspend/hibernate. | |
2853 | 2. PIC interrupts also depend on CPU0. CPU0 can't be | |
2854 | removed if a PIC interrupt is detected. | |
2855 | It's said poweroff/reboot may depend on CPU0 on some | |
2856 | machines although I haven't seen such issues so far | |
2857 | after CPU0 is offline on a few tested machines. | |
2858 | If the dependencies are under your control, you can | |
2859 | turn on cpu0_hotplug. | |
2860 | ||
2861 | nps_mtm_hs_ctr= [KNL,ARC] | |
2862 | This parameter sets the maximum duration, in | |
2863 | cycles, each HW thread of the CTOP can run | |
2864 | without interruptions, before HW switches it. | |
2865 | The actual maximum duration is 16 times this | |
2866 | parameter's value. | |
2867 | Format: integer between 1 and 255 | |
2868 | Default: 255 | |
2869 | ||
2870 | nptcg= [IA-64] Override max number of concurrent global TLB | |
2871 | purges which is reported from either PAL_VM_SUMMARY or | |
2872 | SAL PALO. | |
2873 | ||
2874 | nr_cpus= [SMP] Maximum number of processors that an SMP kernel | |
2875 | could support. nr_cpus=n : n >= 1 limits the kernel to | |
2876 | support 'n' processors. It could be larger than the | |
2877 | number of already plugged CPU during bootup, later in | |
2878 | runtime you can physically add extra cpu until it reaches | |
2879 | n. So during boot up some boot time memory for per-cpu | |
2880 | variables need be pre-allocated for later physical cpu | |
2881 | hot plugging. | |
2882 | ||
2883 | nr_uarts= [SERIAL] maximum number of UARTs to be registered. | |
2884 | ||
2885 | numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. | |
2886 | Allowed values are enable and disable | |
2887 | ||
2888 | numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. | |
2889 | 'node', 'default' can be specified | |
2890 | This can be set from sysctl after boot. | |
2891 | See Documentation/sysctl/vm.txt for details. | |
2892 | ||
2893 | ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. | |
2894 | See Documentation/debugging-via-ohci1394.txt for more | |
2895 | info. | |
2896 | ||
2897 | olpc_ec_timeout= [OLPC] ms delay when issuing EC commands | |
2898 | Rather than timing out after 20 ms if an EC | |
2899 | command is not properly ACKed, override the length | |
2900 | of the timeout. We have interrupts disabled while | |
2901 | waiting for the ACK, so if this is set too high | |
2902 | interrupts *may* be lost! | |
2903 | ||
2904 | omap_mux= [OMAP] Override bootloader pin multiplexing. | |
2905 | Format: <mux_mode0.mode_name=value>... | |
2906 | For example, to override I2C bus2: | |
2907 | omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 | |
2908 | ||
2909 | oprofile.timer= [HW] | |
2910 | Use timer interrupt instead of performance counters | |
2911 | ||
2912 | oprofile.cpu_type= Force an oprofile cpu type | |
2913 | This might be useful if you have an older oprofile | |
2914 | userland or if you want common events. | |
2915 | Format: { arch_perfmon } | |
2916 | arch_perfmon: [X86] Force use of architectural | |
2917 | perfmon on Intel CPUs instead of the | |
2918 | CPU specific event set. | |
2919 | timer: [X86] Force use of architectural NMI | |
2920 | timer mode (see also oprofile.timer | |
2921 | for generic hr timer mode) | |
2922 | ||
2923 | oops=panic Always panic on oopses. Default is to just kill the | |
2924 | process, but there is a small probability of | |
2925 | deadlocking the machine. | |
2926 | This will also cause panics on machine check exceptions. | |
2927 | Useful together with panic=30 to trigger a reboot. | |
2928 | ||
2929 | page_owner= [KNL] Boot-time page_owner enabling option. | |
2930 | Storage of the information about who allocated | |
2931 | each page is disabled in default. With this switch, | |
2932 | we can turn it on. | |
2933 | on: enable the feature | |
2934 | ||
2935 | page_poison= [KNL] Boot-time parameter changing the state of | |
2936 | poisoning on the buddy allocator. | |
2937 | off: turn off poisoning | |
2938 | on: turn on poisoning | |
2939 | ||
2940 | panic= [KNL] Kernel behaviour on panic: delay <timeout> | |
2941 | timeout > 0: seconds before rebooting | |
2942 | timeout = 0: wait forever | |
2943 | timeout < 0: reboot immediately | |
2944 | Format: <timeout> | |
2945 | ||
2946 | panic_on_warn panic() instead of WARN(). Useful to cause kdump | |
2947 | on a WARN(). | |
2948 | ||
2949 | crash_kexec_post_notifiers | |
2950 | Run kdump after running panic-notifiers and dumping | |
2951 | kmsg. This only for the users who doubt kdump always | |
2952 | succeeds in any situation. | |
2953 | Note that this also increases risks of kdump failure, | |
2954 | because some panic notifiers can make the crashed | |
2955 | kernel more unstable. | |
2956 | ||
2957 | parkbd.port= [HW] Parallel port number the keyboard adapter is | |
2958 | connected to, default is 0. | |
2959 | Format: <parport#> | |
2960 | parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, | |
2961 | 0 for XT, 1 for AT (default is AT). | |
2962 | Format: <mode> | |
2963 | ||
2964 | parport= [HW,PPT] Specify parallel ports. 0 disables. | |
2965 | Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } | |
2966 | Use 'auto' to force the driver to use any | |
2967 | IRQ/DMA settings detected (the default is to | |
2968 | ignore detected IRQ/DMA settings because of | |
2969 | possible conflicts). You can specify the base | |
2970 | address, IRQ, and DMA settings; IRQ and DMA | |
2971 | should be numbers, or 'auto' (for using detected | |
2972 | settings on that particular port), or 'nofifo' | |
2973 | (to avoid using a FIFO even if it is detected). | |
2974 | Parallel ports are assigned in the order they | |
2975 | are specified on the command line, starting | |
2976 | with parport0. | |
2977 | ||
2978 | parport_init_mode= [HW,PPT] | |
2979 | Configure VIA parallel port to operate in | |
2980 | a specific mode. This is necessary on Pegasos | |
2981 | computer where firmware has no options for setting | |
2982 | up parallel port mode and sets it to spp. | |
2983 | Currently this function knows 686a and 8231 chips. | |
2984 | Format: [spp|ps2|epp|ecp|ecpepp] | |
2985 | ||
2986 | pause_on_oops= | |
2987 | Halt all CPUs after the first oops has been printed for | |
2988 | the specified number of seconds. This is to be used if | |
2989 | your oopses keep scrolling off the screen. | |
2990 | ||
2991 | pcbit= [HW,ISDN] | |
2992 | ||
2993 | pcd. [PARIDE] | |
2994 | See header of drivers/block/paride/pcd.c. | |
2995 | See also Documentation/blockdev/paride.txt. | |
2996 | ||
2997 | pci=option[,option...] [PCI] various PCI subsystem options: | |
2998 | earlydump [X86] dump PCI config space before the kernel | |
2999 | changes anything | |
3000 | off [X86] don't probe for the PCI bus | |
3001 | bios [X86-32] force use of PCI BIOS, don't access | |
3002 | the hardware directly. Use this if your machine | |
3003 | has a non-standard PCI host bridge. | |
3004 | nobios [X86-32] disallow use of PCI BIOS, only direct | |
3005 | hardware access methods are allowed. Use this | |
3006 | if you experience crashes upon bootup and you | |
3007 | suspect they are caused by the BIOS. | |
3008 | conf1 [X86] Force use of PCI Configuration Access | |
3009 | Mechanism 1 (config address in IO port 0xCF8, | |
3010 | data in IO port 0xCFC, both 32-bit). | |
3011 | conf2 [X86] Force use of PCI Configuration Access | |
3012 | Mechanism 2 (IO port 0xCF8 is an 8-bit port for | |
3013 | the function, IO port 0xCFA, also 8-bit, sets | |
3014 | bus number. The config space is then accessed | |
3015 | through ports 0xC000-0xCFFF). | |
3016 | See http://wiki.osdev.org/PCI for more info | |
3017 | on the configuration access mechanisms. | |
3018 | noaer [PCIE] If the PCIEAER kernel config parameter is | |
3019 | enabled, this kernel boot option can be used to | |
3020 | disable the use of PCIE advanced error reporting. | |
3021 | nodomains [PCI] Disable support for multiple PCI | |
3022 | root domains (aka PCI segments, in ACPI-speak). | |
3023 | nommconf [X86] Disable use of MMCONFIG for PCI | |
3024 | Configuration | |
3025 | check_enable_amd_mmconf [X86] check for and enable | |
3026 | properly configured MMIO access to PCI | |
3027 | config space on AMD family 10h CPU | |
3028 | nomsi [MSI] If the PCI_MSI kernel config parameter is | |
3029 | enabled, this kernel boot option can be used to | |
3030 | disable the use of MSI interrupts system-wide. | |
3031 | noioapicquirk [APIC] Disable all boot interrupt quirks. | |
3032 | Safety option to keep boot IRQs enabled. This | |
3033 | should never be necessary. | |
3034 | ioapicreroute [APIC] Enable rerouting of boot IRQs to the | |
3035 | primary IO-APIC for bridges that cannot disable | |
3036 | boot IRQs. This fixes a source of spurious IRQs | |
3037 | when the system masks IRQs. | |
3038 | noioapicreroute [APIC] Disable workaround that uses the | |
3039 | boot IRQ equivalent of an IRQ that connects to | |
3040 | a chipset where boot IRQs cannot be disabled. | |
3041 | The opposite of ioapicreroute. | |
3042 | biosirq [X86-32] Use PCI BIOS calls to get the interrupt | |
3043 | routing table. These calls are known to be buggy | |
3044 | on several machines and they hang the machine | |
3045 | when used, but on other computers it's the only | |
3046 | way to get the interrupt routing table. Try | |
3047 | this option if the kernel is unable to allocate | |
3048 | IRQs or discover secondary PCI buses on your | |
3049 | motherboard. | |
3050 | rom [X86] Assign address space to expansion ROMs. | |
3051 | Use with caution as certain devices share | |
3052 | address decoders between ROMs and other | |
3053 | resources. | |
3054 | norom [X86] Do not assign address space to | |
3055 | expansion ROMs that do not already have | |
3056 | BIOS assigned address ranges. | |
3057 | nobar [X86] Do not assign address space to the | |
3058 | BARs that weren't assigned by the BIOS. | |
3059 | irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be | |
3060 | assigned automatically to PCI devices. You can | |
3061 | make the kernel exclude IRQs of your ISA cards | |
3062 | this way. | |
3063 | pirqaddr=0xAAAAA [X86] Specify the physical address | |
3064 | of the PIRQ table (normally generated | |
3065 | by the BIOS) if it is outside the | |
3066 | F0000h-100000h range. | |
3067 | lastbus=N [X86] Scan all buses thru bus #N. Can be | |
3068 | useful if the kernel is unable to find your | |
3069 | secondary buses and you want to tell it | |
3070 | explicitly which ones they are. | |
3071 | assign-busses [X86] Always assign all PCI bus | |
3072 | numbers ourselves, overriding | |
3073 | whatever the firmware may have done. | |
3074 | usepirqmask [X86] Honor the possible IRQ mask stored | |
3075 | in the BIOS $PIR table. This is needed on | |
3076 | some systems with broken BIOSes, notably | |
3077 | some HP Pavilion N5400 and Omnibook XE3 | |
3078 | notebooks. This will have no effect if ACPI | |
3079 | IRQ routing is enabled. | |
3080 | noacpi [X86] Do not use ACPI for IRQ routing | |
3081 | or for PCI scanning. | |
3082 | use_crs [X86] Use PCI host bridge window information | |
3083 | from ACPI. On BIOSes from 2008 or later, this | |
3084 | is enabled by default. If you need to use this, | |
3085 | please report a bug. | |
3086 | nocrs [X86] Ignore PCI host bridge windows from ACPI. | |
3087 | If you need to use this, please report a bug. | |
3088 | routeirq Do IRQ routing for all PCI devices. | |
3089 | This is normally done in pci_enable_device(), | |
3090 | so this option is a temporary workaround | |
3091 | for broken drivers that don't call it. | |
3092 | skip_isa_align [X86] do not align io start addr, so can | |
3093 | handle more pci cards | |
3094 | noearly [X86] Don't do any early type 1 scanning. | |
3095 | This might help on some broken boards which | |
3096 | machine check when some devices' config space | |
3097 | is read. But various workarounds are disabled | |
3098 | and some IOMMU drivers will not work. | |
3099 | bfsort Sort PCI devices into breadth-first order. | |
3100 | This sorting is done to get a device | |
3101 | order compatible with older (<= 2.4) kernels. | |
3102 | nobfsort Don't sort PCI devices into breadth-first order. | |
3103 | pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) | |
3104 | tuning and use the BIOS-configured MPS defaults. | |
3105 | pcie_bus_safe Set every device's MPS to the largest value | |
3106 | supported by all devices below the root complex. | |
3107 | pcie_bus_perf Set device MPS to the largest allowable MPS | |
3108 | based on its parent bus. Also set MRRS (Max | |
3109 | Read Request Size) to the largest supported | |
3110 | value (no larger than the MPS that the device | |
3111 | or bus can support) for best performance. | |
3112 | pcie_bus_peer2peer Set every device's MPS to 128B, which | |
3113 | every device is guaranteed to support. This | |
3114 | configuration allows peer-to-peer DMA between | |
3115 | any pair of devices, possibly at the cost of | |
3116 | reduced performance. This also guarantees | |
3117 | that hot-added devices will work. | |
3118 | cbiosize=nn[KMG] The fixed amount of bus space which is | |
3119 | reserved for the CardBus bridge's IO window. | |
3120 | The default value is 256 bytes. | |
3121 | cbmemsize=nn[KMG] The fixed amount of bus space which is | |
3122 | reserved for the CardBus bridge's memory | |
3123 | window. The default value is 64 megabytes. | |
3124 | resource_alignment= | |
3125 | Format: | |
3126 | [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] | |
3127 | [<order of align>@]pci:<vendor>:<device>\ | |
3128 | [:<subvendor>:<subdevice>][; ...] | |
3129 | Specifies alignment and device to reassign | |
3130 | aligned memory resources. | |
3131 | If <order of align> is not specified, | |
3132 | PAGE_SIZE is used as alignment. | |
3133 | PCI-PCI bridge can be specified, if resource | |
3134 | windows need to be expanded. | |
3135 | To specify the alignment for several | |
3136 | instances of a device, the PCI vendor, | |
3137 | device, subvendor, and subdevice may be | |
3138 | specified, e.g., 4096@pci:8086:9c22:103c:198f | |
3139 | ecrc= Enable/disable PCIe ECRC (transaction layer | |
3140 | end-to-end CRC checking). | |
3141 | bios: Use BIOS/firmware settings. This is the | |
3142 | the default. | |
3143 | off: Turn ECRC off | |
3144 | on: Turn ECRC on. | |
3145 | hpiosize=nn[KMG] The fixed amount of bus space which is | |
3146 | reserved for hotplug bridge's IO window. | |
3147 | Default size is 256 bytes. | |
3148 | hpmemsize=nn[KMG] The fixed amount of bus space which is | |
3149 | reserved for hotplug bridge's memory window. | |
3150 | Default size is 2 megabytes. | |
3151 | hpbussize=nn The minimum amount of additional bus numbers | |
3152 | reserved for buses below a hotplug bridge. | |
3153 | Default is 1. | |
3154 | realloc= Enable/disable reallocating PCI bridge resources | |
3155 | if allocations done by BIOS are too small to | |
3156 | accommodate resources required by all child | |
3157 | devices. | |
3158 | off: Turn realloc off | |
3159 | on: Turn realloc on | |
3160 | realloc same as realloc=on | |
3161 | noari do not use PCIe ARI. | |
3162 | noats [PCIE, Intel-IOMMU, AMD-IOMMU] | |
3163 | do not use PCIe ATS (and IOMMU device IOTLB). | |
3164 | pcie_scan_all Scan all possible PCIe devices. Otherwise we | |
3165 | only look for one device below a PCIe downstream | |
3166 | port. | |
3167 | big_root_window Try to add a big 64bit memory window to the PCIe | |
3168 | root complex on AMD CPUs. Some GFX hardware | |
3169 | can resize a BAR to allow access to all VRAM. | |
3170 | Adding the window is slightly risky (it may | |
3171 | conflict with unreported devices), so this | |
3172 | taints the kernel. | |
3173 | ||
3174 | pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power | |
3175 | Management. | |
3176 | off Disable ASPM. | |
3177 | force Enable ASPM even on devices that claim not to support it. | |
3178 | WARNING: Forcing ASPM on may cause system lockups. | |
3179 | ||
3180 | pcie_ports= [PCIE] PCIe port services handling: | |
3181 | native Use native PCIe services (PME, AER, DPC, PCIe hotplug) | |
3182 | even if the platform doesn't give the OS permission to | |
3183 | use them. This may cause conflicts if the platform | |
3184 | also tries to use these services. | |
3185 | compat Disable native PCIe services (PME, AER, DPC, PCIe | |
3186 | hotplug). | |
3187 | ||
3188 | pcie_port_pm= [PCIE] PCIe port power management handling: | |
3189 | off Disable power management of all PCIe ports | |
3190 | force Forcibly enable power management of all PCIe ports | |
3191 | ||
3192 | pcie_pme= [PCIE,PM] Native PCIe PME signaling options: | |
3193 | nomsi Do not use MSI for native PCIe PME signaling (this makes | |
3194 | all PCIe root ports use INTx for all services). | |
3195 | ||
3196 | pcmv= [HW,PCMCIA] BadgePAD 4 | |
3197 | ||
3198 | pd_ignore_unused | |
3199 | [PM] | |
3200 | Keep all power-domains already enabled by bootloader on, | |
3201 | even if no driver has claimed them. This is useful | |
3202 | for debug and development, but should not be | |
3203 | needed on a platform with proper driver support. | |
3204 | ||
3205 | pd. [PARIDE] | |
3206 | See Documentation/blockdev/paride.txt. | |
3207 | ||
3208 | pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at | |
3209 | boot time. | |
3210 | Format: { 0 | 1 } | |
3211 | See arch/parisc/kernel/pdc_chassis.c | |
3212 | ||
3213 | percpu_alloc= Select which percpu first chunk allocator to use. | |
3214 | Currently supported values are "embed" and "page". | |
3215 | Archs may support subset or none of the selections. | |
3216 | See comments in mm/percpu.c for details on each | |
3217 | allocator. This parameter is primarily for debugging | |
3218 | and performance comparison. | |
3219 | ||
3220 | pf. [PARIDE] | |
3221 | See Documentation/blockdev/paride.txt. | |
3222 | ||
3223 | pg. [PARIDE] | |
3224 | See Documentation/blockdev/paride.txt. | |
3225 | ||
3226 | pirq= [SMP,APIC] Manual mp-table setup | |
3227 | See Documentation/x86/i386/IO-APIC.txt. | |
3228 | ||
3229 | plip= [PPT,NET] Parallel port network link | |
3230 | Format: { parport<nr> | timid | 0 } | |
3231 | See also Documentation/admin-guide/parport.rst. | |
3232 | ||
3233 | pmtmr= [X86] Manual setup of pmtmr I/O Port. | |
3234 | Override pmtimer IOPort with a hex value. | |
3235 | e.g. pmtmr=0x508 | |
3236 | ||
3237 | pnp.debug=1 [PNP] | |
3238 | Enable PNP debug messages (depends on the | |
3239 | CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time | |
3240 | via /sys/module/pnp/parameters/debug. We always show | |
3241 | current resource usage; turning this on also shows | |
3242 | possible settings and some assignment information. | |
3243 | ||
3244 | pnpacpi= [ACPI] | |
3245 | { off } | |
3246 | ||
3247 | pnpbios= [ISAPNP] | |
3248 | { on | off | curr | res | no-curr | no-res } | |
3249 | ||
3250 | pnp_reserve_irq= | |
3251 | [ISAPNP] Exclude IRQs for the autoconfiguration | |
3252 | ||
3253 | pnp_reserve_dma= | |
3254 | [ISAPNP] Exclude DMAs for the autoconfiguration | |
3255 | ||
3256 | pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration | |
3257 | Ranges are in pairs (I/O port base and size). | |
3258 | ||
3259 | pnp_reserve_mem= | |
3260 | [ISAPNP] Exclude memory regions for the | |
3261 | autoconfiguration. | |
3262 | Ranges are in pairs (memory base and size). | |
3263 | ||
3264 | ports= [IP_VS_FTP] IPVS ftp helper module | |
3265 | Default is 21. | |
3266 | Up to 8 (IP_VS_APP_MAX_PORTS) ports | |
3267 | may be specified. | |
3268 | Format: <port>,<port>.... | |
3269 | ||
3270 | powersave=off [PPC] This option disables power saving features. | |
3271 | It specifically disables cpuidle and sets the | |
3272 | platform machine description specific power_save | |
3273 | function to NULL. On Idle the CPU just reduces | |
3274 | execution priority. | |
3275 | ||
3276 | ppc_strict_facility_enable | |
3277 | [PPC] This option catches any kernel floating point, | |
3278 | Altivec, VSX and SPE outside of regions specifically | |
3279 | allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). | |
3280 | There is some performance impact when enabling this. | |
3281 | ||
3282 | ppc_tm= [PPC] | |
3283 | Format: {"off"} | |
3284 | Disable Hardware Transactional Memory | |
3285 | ||
3286 | print-fatal-signals= | |
3287 | [KNL] debug: print fatal signals | |
3288 | ||
3289 | If enabled, warn about various signal handling | |
3290 | related application anomalies: too many signals, | |
3291 | too many POSIX.1 timers, fatal signals causing a | |
3292 | coredump - etc. | |
3293 | ||
3294 | If you hit the warning due to signal overflow, | |
3295 | you might want to try "ulimit -i unlimited". | |
3296 | ||
3297 | default: off. | |
3298 | ||
3299 | printk.always_kmsg_dump= | |
3300 | Trigger kmsg_dump for cases other than kernel oops or | |
3301 | panics | |
3302 | Format: <bool> (1/Y/y=enable, 0/N/n=disable) | |
3303 | default: disabled | |
3304 | ||
3305 | printk.devkmsg={on,off,ratelimit} | |
3306 | Control writing to /dev/kmsg. | |
3307 | on - unlimited logging to /dev/kmsg from userspace | |
3308 | off - logging to /dev/kmsg disabled | |
3309 | ratelimit - ratelimit the logging | |
3310 | Default: ratelimit | |
3311 | ||
3312 | printk.time= Show timing data prefixed to each printk message line | |
3313 | Format: <bool> (1/Y/y=enable, 0/N/n=disable) | |
3314 | ||
3315 | processor.max_cstate= [HW,ACPI] | |
3316 | Limit processor to maximum C-state | |
3317 | max_cstate=9 overrides any DMI blacklist limit. | |
3318 | ||
3319 | processor.nocst [HW,ACPI] | |
3320 | Ignore the _CST method to determine C-states, | |
3321 | instead using the legacy FADT method | |
3322 | ||
3323 | profile= [KNL] Enable kernel profiling via /proc/profile | |
3324 | Format: [<profiletype>,]<number> | |
3325 | Param: <profiletype>: "schedule", "sleep", or "kvm" | |
3326 | [defaults to kernel profiling] | |
3327 | Param: "schedule" - profile schedule points. | |
3328 | Param: "sleep" - profile D-state sleeping (millisecs). | |
3329 | Requires CONFIG_SCHEDSTATS | |
3330 | Param: "kvm" - profile VM exits. | |
3331 | Param: <number> - step/bucket size as a power of 2 for | |
3332 | statistical time based profiling. | |
3333 | ||
3334 | prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk | |
3335 | before loading. | |
3336 | See Documentation/blockdev/ramdisk.txt. | |
3337 | ||
3338 | psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to | |
3339 | probe for; one of (bare|imps|exps|lifebook|any). | |
3340 | psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports | |
3341 | per second. | |
3342 | psmouse.resetafter= [HW,MOUSE] | |
3343 | Try to reset the device after so many bad packets | |
3344 | (0 = never). | |
3345 | psmouse.resolution= | |
3346 | [HW,MOUSE] Set desired mouse resolution, in dpi. | |
3347 | psmouse.smartscroll= | |
3348 | [HW,MOUSE] Controls Logitech smartscroll autorepeat. | |
3349 | 0 = disabled, 1 = enabled (default). | |
3350 | ||
3351 | pstore.backend= Specify the name of the pstore backend to use | |
3352 | ||
3353 | pt. [PARIDE] | |
3354 | See Documentation/blockdev/paride.txt. | |
3355 | ||
3356 | pti= [X86_64] Control Page Table Isolation of user and | |
3357 | kernel address spaces. Disabling this feature | |
3358 | removes hardening, but improves performance of | |
3359 | system calls and interrupts. | |
3360 | ||
3361 | on - unconditionally enable | |
3362 | off - unconditionally disable | |
3363 | auto - kernel detects whether your CPU model is | |
3364 | vulnerable to issues that PTI mitigates | |
3365 | ||
3366 | Not specifying this option is equivalent to pti=auto. | |
3367 | ||
3368 | nopti [X86_64] | |
3369 | Equivalent to pti=off | |
3370 | ||
3371 | pty.legacy_count= | |
3372 | [KNL] Number of legacy pty's. Overwrites compiled-in | |
3373 | default number. | |
3374 | ||
3375 | quiet [KNL] Disable most log messages | |
3376 | ||
3377 | r128= [HW,DRM] | |
3378 | ||
3379 | raid= [HW,RAID] | |
3380 | See Documentation/admin-guide/md.rst. | |
3381 | ||
3382 | ramdisk_size= [RAM] Sizes of RAM disks in kilobytes | |
3383 | See Documentation/blockdev/ramdisk.txt. | |
3384 | ||
3385 | ras=option[,option,...] [KNL] RAS-specific options | |
3386 | ||
3387 | cec_disable [X86] | |
3388 | Disable the Correctable Errors Collector, | |
3389 | see CONFIG_RAS_CEC help text. | |
3390 | ||
3391 | rcu_nocbs= [KNL] | |
3392 | The argument is a cpu list, as described above. | |
3393 | ||
3394 | In kernels built with CONFIG_RCU_NOCB_CPU=y, set | |
3395 | the specified list of CPUs to be no-callback CPUs. | |
3396 | Invocation of these CPUs' RCU callbacks will | |
3397 | be offloaded to "rcuox/N" kthreads created for | |
3398 | that purpose, where "x" is "b" for RCU-bh, "p" | |
3399 | for RCU-preempt, and "s" for RCU-sched, and "N" | |
3400 | is the CPU number. This reduces OS jitter on the | |
3401 | offloaded CPUs, which can be useful for HPC and | |
3402 | real-time workloads. It can also improve energy | |
3403 | efficiency for asymmetric multiprocessors. | |
3404 | ||
3405 | rcu_nocb_poll [KNL] | |
3406 | Rather than requiring that offloaded CPUs | |
3407 | (specified by rcu_nocbs= above) explicitly | |
3408 | awaken the corresponding "rcuoN" kthreads, | |
3409 | make these kthreads poll for callbacks. | |
3410 | This improves the real-time response for the | |
3411 | offloaded CPUs by relieving them of the need to | |
3412 | wake up the corresponding kthread, but degrades | |
3413 | energy efficiency by requiring that the kthreads | |
3414 | periodically wake up to do the polling. | |
3415 | ||
3416 | rcutree.blimit= [KNL] | |
3417 | Set maximum number of finished RCU callbacks to | |
3418 | process in one batch. | |
3419 | ||
3420 | rcutree.dump_tree= [KNL] | |
3421 | Dump the structure of the rcu_node combining tree | |
3422 | out at early boot. This is used for diagnostic | |
3423 | purposes, to verify correct tree setup. | |
3424 | ||
3425 | rcutree.gp_cleanup_delay= [KNL] | |
3426 | Set the number of jiffies to delay each step of | |
3427 | RCU grace-period cleanup. | |
3428 | ||
3429 | rcutree.gp_init_delay= [KNL] | |
3430 | Set the number of jiffies to delay each step of | |
3431 | RCU grace-period initialization. | |
3432 | ||
3433 | rcutree.gp_preinit_delay= [KNL] | |
3434 | Set the number of jiffies to delay each step of | |
3435 | RCU grace-period pre-initialization, that is, | |
3436 | the propagation of recent CPU-hotplug changes up | |
3437 | the rcu_node combining tree. | |
3438 | ||
3439 | rcutree.rcu_fanout_exact= [KNL] | |
3440 | Disable autobalancing of the rcu_node combining | |
3441 | tree. This is used by rcutorture, and might | |
3442 | possibly be useful for architectures having high | |
3443 | cache-to-cache transfer latencies. | |
3444 | ||
3445 | rcutree.rcu_fanout_leaf= [KNL] | |
3446 | Change the number of CPUs assigned to each | |
3447 | leaf rcu_node structure. Useful for very | |
3448 | large systems, which will choose the value 64, | |
3449 | and for NUMA systems with large remote-access | |
3450 | latencies, which will choose a value aligned | |
3451 | with the appropriate hardware boundaries. | |
3452 | ||
3453 | rcutree.jiffies_till_sched_qs= [KNL] | |
3454 | Set required age in jiffies for a | |
3455 | given grace period before RCU starts | |
3456 | soliciting quiescent-state help from | |
3457 | rcu_note_context_switch(). | |
3458 | ||
3459 | rcutree.jiffies_till_first_fqs= [KNL] | |
3460 | Set delay from grace-period initialization to | |
3461 | first attempt to force quiescent states. | |
3462 | Units are jiffies, minimum value is zero, | |
3463 | and maximum value is HZ. | |
3464 | ||
3465 | rcutree.jiffies_till_next_fqs= [KNL] | |
3466 | Set delay between subsequent attempts to force | |
3467 | quiescent states. Units are jiffies, minimum | |
3468 | value is one, and maximum value is HZ. | |
3469 | ||
3470 | rcutree.kthread_prio= [KNL,BOOT] | |
3471 | Set the SCHED_FIFO priority of the RCU per-CPU | |
3472 | kthreads (rcuc/N). This value is also used for | |
3473 | the priority of the RCU boost threads (rcub/N) | |
3474 | and for the RCU grace-period kthreads (rcu_bh, | |
3475 | rcu_preempt, and rcu_sched). If RCU_BOOST is | |
3476 | set, valid values are 1-99 and the default is 1 | |
3477 | (the least-favored priority). Otherwise, when | |
3478 | RCU_BOOST is not set, valid values are 0-99 and | |
3479 | the default is zero (non-realtime operation). | |
3480 | ||
3481 | rcutree.rcu_nocb_leader_stride= [KNL] | |
3482 | Set the number of NOCB kthread groups, which | |
3483 | defaults to the square root of the number of | |
3484 | CPUs. Larger numbers reduces the wakeup overhead | |
3485 | on the per-CPU grace-period kthreads, but increases | |
3486 | that same overhead on each group's leader. | |
3487 | ||
3488 | rcutree.qhimark= [KNL] | |
3489 | Set threshold of queued RCU callbacks beyond which | |
3490 | batch limiting is disabled. | |
3491 | ||
3492 | rcutree.qlowmark= [KNL] | |
3493 | Set threshold of queued RCU callbacks below which | |
3494 | batch limiting is re-enabled. | |
3495 | ||
3496 | rcutree.rcu_idle_gp_delay= [KNL] | |
3497 | Set wakeup interval for idle CPUs that have | |
3498 | RCU callbacks (RCU_FAST_NO_HZ=y). | |
3499 | ||
3500 | rcutree.rcu_idle_lazy_gp_delay= [KNL] | |
3501 | Set wakeup interval for idle CPUs that have | |
3502 | only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). | |
3503 | Lazy RCU callbacks are those which RCU can | |
3504 | prove do nothing more than free memory. | |
3505 | ||
3506 | rcutree.rcu_kick_kthreads= [KNL] | |
3507 | Cause the grace-period kthread to get an extra | |
3508 | wake_up() if it sleeps three times longer than | |
3509 | it should at force-quiescent-state time. | |
3510 | This wake_up() will be accompanied by a | |
3511 | WARN_ONCE() splat and an ftrace_dump(). | |
3512 | ||
3513 | rcuperf.gp_async= [KNL] | |
3514 | Measure performance of asynchronous | |
3515 | grace-period primitives such as call_rcu(). | |
3516 | ||
3517 | rcuperf.gp_async_max= [KNL] | |
3518 | Specify the maximum number of outstanding | |
3519 | callbacks per writer thread. When a writer | |
3520 | thread exceeds this limit, it invokes the | |
3521 | corresponding flavor of rcu_barrier() to allow | |
3522 | previously posted callbacks to drain. | |
3523 | ||
3524 | rcuperf.gp_exp= [KNL] | |
3525 | Measure performance of expedited synchronous | |
3526 | grace-period primitives. | |
3527 | ||
3528 | rcuperf.holdoff= [KNL] | |
3529 | Set test-start holdoff period. The purpose of | |
3530 | this parameter is to delay the start of the | |
3531 | test until boot completes in order to avoid | |
3532 | interference. | |
3533 | ||
3534 | rcuperf.nreaders= [KNL] | |
3535 | Set number of RCU readers. The value -1 selects | |
3536 | N, where N is the number of CPUs. A value | |
3537 | "n" less than -1 selects N-n+1, where N is again | |
3538 | the number of CPUs. For example, -2 selects N | |
3539 | (the number of CPUs), -3 selects N+1, and so on. | |
3540 | A value of "n" less than or equal to -N selects | |
3541 | a single reader. | |
3542 | ||
3543 | rcuperf.nwriters= [KNL] | |
3544 | Set number of RCU writers. The values operate | |
3545 | the same as for rcuperf.nreaders. | |
3546 | N, where N is the number of CPUs | |
3547 | ||
3548 | rcuperf.perf_type= [KNL] | |
3549 | Specify the RCU implementation to test. | |
3550 | ||
3551 | rcuperf.shutdown= [KNL] | |
3552 | Shut the system down after performance tests | |
3553 | complete. This is useful for hands-off automated | |
3554 | testing. | |
3555 | ||
3556 | rcuperf.verbose= [KNL] | |
3557 | Enable additional printk() statements. | |
3558 | ||
3559 | rcuperf.writer_holdoff= [KNL] | |
3560 | Write-side holdoff between grace periods, | |
3561 | in microseconds. The default of zero says | |
3562 | no holdoff. | |
3563 | ||
3564 | rcutorture.cbflood_inter_holdoff= [KNL] | |
3565 | Set holdoff time (jiffies) between successive | |
3566 | callback-flood tests. | |
3567 | ||
3568 | rcutorture.cbflood_intra_holdoff= [KNL] | |
3569 | Set holdoff time (jiffies) between successive | |
3570 | bursts of callbacks within a given callback-flood | |
3571 | test. | |
3572 | ||
3573 | rcutorture.cbflood_n_burst= [KNL] | |
3574 | Set the number of bursts making up a given | |
3575 | callback-flood test. Set this to zero to | |
3576 | disable callback-flood testing. | |
3577 | ||
3578 | rcutorture.cbflood_n_per_burst= [KNL] | |
3579 | Set the number of callbacks to be registered | |
3580 | in a given burst of a callback-flood test. | |
3581 | ||
3582 | rcutorture.fqs_duration= [KNL] | |
3583 | Set duration of force_quiescent_state bursts | |
3584 | in microseconds. | |
3585 | ||
3586 | rcutorture.fqs_holdoff= [KNL] | |
3587 | Set holdoff time within force_quiescent_state bursts | |
3588 | in microseconds. | |
3589 | ||
3590 | rcutorture.fqs_stutter= [KNL] | |
3591 | Set wait time between force_quiescent_state bursts | |
3592 | in seconds. | |
3593 | ||
3594 | rcutorture.gp_cond= [KNL] | |
3595 | Use conditional/asynchronous update-side | |
3596 | primitives, if available. | |
3597 | ||
3598 | rcutorture.gp_exp= [KNL] | |
3599 | Use expedited update-side primitives, if available. | |
3600 | ||
3601 | rcutorture.gp_normal= [KNL] | |
3602 | Use normal (non-expedited) asynchronous | |
3603 | update-side primitives, if available. | |
3604 | ||
3605 | rcutorture.gp_sync= [KNL] | |
3606 | Use normal (non-expedited) synchronous | |
3607 | update-side primitives, if available. If all | |
3608 | of rcutorture.gp_cond=, rcutorture.gp_exp=, | |
3609 | rcutorture.gp_normal=, and rcutorture.gp_sync= | |
3610 | are zero, rcutorture acts as if is interpreted | |
3611 | they are all non-zero. | |
3612 | ||
3613 | rcutorture.n_barrier_cbs= [KNL] | |
3614 | Set callbacks/threads for rcu_barrier() testing. | |
3615 | ||
3616 | rcutorture.nfakewriters= [KNL] | |
3617 | Set number of concurrent RCU writers. These just | |
3618 | stress RCU, they don't participate in the actual | |
3619 | test, hence the "fake". | |
3620 | ||
3621 | rcutorture.nreaders= [KNL] | |
3622 | Set number of RCU readers. The value -1 selects | |
3623 | N-1, where N is the number of CPUs. A value | |
3624 | "n" less than -1 selects N-n-2, where N is again | |
3625 | the number of CPUs. For example, -2 selects N | |
3626 | (the number of CPUs), -3 selects N+1, and so on. | |
3627 | ||
3628 | rcutorture.object_debug= [KNL] | |
3629 | Enable debug-object double-call_rcu() testing. | |
3630 | ||
3631 | rcutorture.onoff_holdoff= [KNL] | |
3632 | Set time (s) after boot for CPU-hotplug testing. | |
3633 | ||
3634 | rcutorture.onoff_interval= [KNL] | |
3635 | Set time (s) between CPU-hotplug operations, or | |
3636 | zero to disable CPU-hotplug testing. | |
3637 | ||
3638 | rcutorture.shuffle_interval= [KNL] | |
3639 | Set task-shuffle interval (s). Shuffling tasks | |
3640 | allows some CPUs to go into dyntick-idle mode | |
3641 | during the rcutorture test. | |
3642 | ||
3643 | rcutorture.shutdown_secs= [KNL] | |
3644 | Set time (s) after boot system shutdown. This | |
3645 | is useful for hands-off automated testing. | |
3646 | ||
3647 | rcutorture.stall_cpu= [KNL] | |
3648 | Duration of CPU stall (s) to test RCU CPU stall | |
3649 | warnings, zero to disable. | |
3650 | ||
3651 | rcutorture.stall_cpu_holdoff= [KNL] | |
3652 | Time to wait (s) after boot before inducing stall. | |
3653 | ||
3654 | rcutorture.stall_cpu_irqsoff= [KNL] | |
3655 | Disable interrupts while stalling if set. | |
3656 | ||
3657 | rcutorture.stat_interval= [KNL] | |
3658 | Time (s) between statistics printk()s. | |
3659 | ||
3660 | rcutorture.stutter= [KNL] | |
3661 | Time (s) to stutter testing, for example, specifying | |
3662 | five seconds causes the test to run for five seconds, | |
3663 | wait for five seconds, and so on. This tests RCU's | |
3664 | ability to transition abruptly to and from idle. | |
3665 | ||
3666 | rcutorture.test_boost= [KNL] | |
3667 | Test RCU priority boosting? 0=no, 1=maybe, 2=yes. | |
3668 | "Maybe" means test if the RCU implementation | |
3669 | under test support RCU priority boosting. | |
3670 | ||
3671 | rcutorture.test_boost_duration= [KNL] | |
3672 | Duration (s) of each individual boost test. | |
3673 | ||
3674 | rcutorture.test_boost_interval= [KNL] | |
3675 | Interval (s) between each boost test. | |
3676 | ||
3677 | rcutorture.test_no_idle_hz= [KNL] | |
3678 | Test RCU's dyntick-idle handling. See also the | |
3679 | rcutorture.shuffle_interval parameter. | |
3680 | ||
3681 | rcutorture.torture_type= [KNL] | |
3682 | Specify the RCU implementation to test. | |
3683 | ||
3684 | rcutorture.verbose= [KNL] | |
3685 | Enable additional printk() statements. | |
3686 | ||
3687 | rcupdate.rcu_cpu_stall_suppress= [KNL] | |
3688 | Suppress RCU CPU stall warning messages. | |
3689 | ||
3690 | rcupdate.rcu_cpu_stall_timeout= [KNL] | |
3691 | Set timeout for RCU CPU stall warning messages. | |
3692 | ||
3693 | rcupdate.rcu_expedited= [KNL] | |
3694 | Use expedited grace-period primitives, for | |
3695 | example, synchronize_rcu_expedited() instead | |
3696 | of synchronize_rcu(). This reduces latency, | |
3697 | but can increase CPU utilization, degrade | |
3698 | real-time latency, and degrade energy efficiency. | |
3699 | No effect on CONFIG_TINY_RCU kernels. | |
3700 | ||
3701 | rcupdate.rcu_normal= [KNL] | |
3702 | Use only normal grace-period primitives, | |
3703 | for example, synchronize_rcu() instead of | |
3704 | synchronize_rcu_expedited(). This improves | |
3705 | real-time latency, CPU utilization, and | |
3706 | energy efficiency, but can expose users to | |
3707 | increased grace-period latency. This parameter | |
3708 | overrides rcupdate.rcu_expedited. No effect on | |
3709 | CONFIG_TINY_RCU kernels. | |
3710 | ||
3711 | rcupdate.rcu_normal_after_boot= [KNL] | |
3712 | Once boot has completed (that is, after | |
3713 | rcu_end_inkernel_boot() has been invoked), use | |
3714 | only normal grace-period primitives. No effect | |
3715 | on CONFIG_TINY_RCU kernels. | |
3716 | ||
3717 | rcupdate.rcu_task_stall_timeout= [KNL] | |
3718 | Set timeout in jiffies for RCU task stall warning | |
3719 | messages. Disable with a value less than or equal | |
3720 | to zero. | |
3721 | ||
3722 | rcupdate.rcu_self_test= [KNL] | |
3723 | Run the RCU early boot self tests | |
3724 | ||
3725 | rcupdate.rcu_self_test_bh= [KNL] | |
3726 | Run the RCU bh early boot self tests | |
3727 | ||
3728 | rcupdate.rcu_self_test_sched= [KNL] | |
3729 | Run the RCU sched early boot self tests | |
3730 | ||
3731 | rdinit= [KNL] | |
3732 | Format: <full_path> | |
3733 | Run specified binary instead of /init from the ramdisk, | |
3734 | used for early userspace startup. See initrd. | |
3735 | ||
3736 | rdt= [HW,X86,RDT] | |
3737 | Turn on/off individual RDT features. List is: | |
3738 | cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp, | |
3739 | mba. | |
3740 | E.g. to turn on cmt and turn off mba use: | |
3741 | rdt=cmt,!mba | |
3742 | ||
3743 | reboot= [KNL] | |
3744 | Format (x86 or x86_64): | |
3745 | [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ | |
3746 | [[,]s[mp]#### \ | |
3747 | [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ | |
3748 | [[,]f[orce] | |
3749 | Where reboot_mode is one of warm (soft) or cold (hard) or gpio, | |
3750 | reboot_type is one of bios, acpi, kbd, triple, efi, or pci, | |
3751 | reboot_force is either force or not specified, | |
3752 | reboot_cpu is s[mp]#### with #### being the processor | |
3753 | to be used for rebooting. | |
3754 | ||
3755 | relax_domain_level= | |
3756 | [KNL, SMP] Set scheduler's default relax_domain_level. | |
3757 | See Documentation/cgroup-v1/cpusets.txt. | |
3758 | ||
3759 | reserve= [KNL,BUGS] Force kernel to ignore I/O ports or memory | |
3760 | Format: <base1>,<size1>[,<base2>,<size2>,...] | |
3761 | Reserve I/O ports or memory so the kernel won't use | |
3762 | them. If <base> is less than 0x10000, the region | |
3763 | is assumed to be I/O ports; otherwise it is memory. | |
3764 | ||
3765 | reservetop= [X86-32] | |
3766 | Format: nn[KMG] | |
3767 | Reserves a hole at the top of the kernel virtual | |
3768 | address space. | |
3769 | ||
3770 | reservelow= [X86] | |
3771 | Format: nn[K] | |
3772 | Set the amount of memory to reserve for BIOS at | |
3773 | the bottom of the address space. | |
3774 | ||
3775 | reset_devices [KNL] Force drivers to reset the underlying device | |
3776 | during initialization. | |
3777 | ||
3778 | resume= [SWSUSP] | |
3779 | Specify the partition device for software suspend | |
3780 | Format: | |
3781 | {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>} | |
3782 | ||
3783 | resume_offset= [SWSUSP] | |
3784 | Specify the offset from the beginning of the partition | |
3785 | given by "resume=" at which the swap header is located, | |
3786 | in <PAGE_SIZE> units (needed only for swap files). | |
3787 | See Documentation/power/swsusp-and-swap-files.txt | |
3788 | ||
3789 | resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to | |
3790 | read the resume files | |
3791 | ||
3792 | resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up. | |
3793 | Useful for devices that are detected asynchronously | |
3794 | (e.g. USB and MMC devices). | |
3795 | ||
3796 | hibernate= [HIBERNATION] | |
3797 | noresume Don't check if there's a hibernation image | |
3798 | present during boot. | |
3799 | nocompress Don't compress/decompress hibernation images. | |
3800 | no Disable hibernation and resume. | |
3801 | protect_image Turn on image protection during restoration | |
3802 | (that will set all pages holding image data | |
3803 | during restoration read-only). | |
3804 | ||
3805 | retain_initrd [RAM] Keep initrd memory after extraction | |
3806 | ||
3807 | rfkill.default_state= | |
3808 | 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm, | |
3809 | etc. communication is blocked by default. | |
3810 | 1 Unblocked. | |
3811 | ||
3812 | rfkill.master_switch_mode= | |
3813 | 0 The "airplane mode" button does nothing. | |
3814 | 1 The "airplane mode" button toggles between everything | |
3815 | blocked and the previous configuration. | |
3816 | 2 The "airplane mode" button toggles between everything | |
3817 | blocked and everything unblocked. | |
3818 | ||
3819 | rhash_entries= [KNL,NET] | |
3820 | Set number of hash buckets for route cache | |
3821 | ||
3822 | ring3mwait=disable | |
3823 | [KNL] Disable ring 3 MONITOR/MWAIT feature on supported | |
3824 | CPUs. | |
3825 | ||
3826 | ro [KNL] Mount root device read-only on boot | |
3827 | ||
3828 | rodata= [KNL] | |
3829 | on Mark read-only kernel memory as read-only (default). | |
3830 | off Leave read-only kernel memory writable for debugging. | |
3831 | ||
3832 | rockchip.usb_uart | |
3833 | Enable the uart passthrough on the designated usb port | |
3834 | on Rockchip SoCs. When active, the signals of the | |
3835 | debug-uart get routed to the D+ and D- pins of the usb | |
3836 | port and the regular usb controller gets disabled. | |
3837 | ||
3838 | root= [KNL] Root filesystem | |
3839 | See name_to_dev_t comment in init/do_mounts.c. | |
3840 | ||
3841 | rootdelay= [KNL] Delay (in seconds) to pause before attempting to | |
3842 | mount the root filesystem | |
3843 | ||
3844 | rootflags= [KNL] Set root filesystem mount option string | |
3845 | ||
3846 | rootfstype= [KNL] Set root filesystem type | |
3847 | ||
3848 | rootwait [KNL] Wait (indefinitely) for root device to show up. | |
3849 | Useful for devices that are detected asynchronously | |
3850 | (e.g. USB and MMC devices). | |
3851 | ||
3852 | rproc_mem=nn[KMG][@address] | |
3853 | [KNL,ARM,CMA] Remoteproc physical memory block. | |
3854 | Memory area to be used by remote processor image, | |
3855 | managed by CMA. | |
3856 | ||
3857 | rw [KNL] Mount root device read-write on boot | |
3858 | ||
3859 | S [KNL] Run init in single mode | |
3860 | ||
3861 | s390_iommu= [HW,S390] | |
3862 | Set s390 IOTLB flushing mode | |
3863 | strict | |
3864 | With strict flushing every unmap operation will result in | |
3865 | an IOTLB flush. Default is lazy flushing before reuse, | |
3866 | which is faster. | |
3867 | ||
3868 | sa1100ir [NET] | |
3869 | See drivers/net/irda/sa1100_ir.c. | |
3870 | ||
3871 | sbni= [NET] Granch SBNI12 leased line adapter | |
3872 | ||
3873 | sched_debug [KNL] Enables verbose scheduler debug messages. | |
3874 | ||
3875 | schedstats= [KNL,X86] Enable or disable scheduled statistics. | |
3876 | Allowed values are enable and disable. This feature | |
3877 | incurs a small amount of overhead in the scheduler | |
3878 | but is useful for debugging and performance tuning. | |
3879 | ||
3880 | skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate | |
3881 | xtime_lock contention on larger systems, and/or RCU lock | |
3882 | contention on all systems with CONFIG_MAXSMP set. | |
3883 | Format: { "0" | "1" } | |
3884 | 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1" | |
3885 | 1 -- enable. | |
3886 | Note: increases power consumption, thus should only be | |
3887 | enabled if running jitter sensitive (HPC/RT) workloads. | |
3888 | ||
3889 | security= [SECURITY] Choose a security module to enable at boot. | |
3890 | If this boot parameter is not specified, only the first | |
3891 | security module asking for security registration will be | |
3892 | loaded. An invalid security module name will be treated | |
3893 | as if no module has been chosen. | |
3894 | ||
3895 | selinux= [SELINUX] Disable or enable SELinux at boot time. | |
3896 | Format: { "0" | "1" } | |
3897 | See security/selinux/Kconfig help text. | |
3898 | 0 -- disable. | |
3899 | 1 -- enable. | |
3900 | Default value is set via kernel config option. | |
3901 | If enabled at boot time, /selinux/disable can be used | |
3902 | later to disable prior to initial policy load. | |
3903 | ||
3904 | apparmor= [APPARMOR] Disable or enable AppArmor at boot time | |
3905 | Format: { "0" | "1" } | |
3906 | See security/apparmor/Kconfig help text | |
3907 | 0 -- disable. | |
3908 | 1 -- enable. | |
3909 | Default value is set via kernel config option. | |
3910 | ||
3911 | serialnumber [BUGS=X86-32] | |
3912 | ||
3913 | shapers= [NET] | |
3914 | Maximal number of shapers. | |
3915 | ||
3916 | simeth= [IA-64] | |
3917 | simscsi= | |
3918 | ||
3919 | slram= [HW,MTD] | |
3920 | ||
3921 | slab_nomerge [MM] | |
3922 | Disable merging of slabs with similar size. May be | |
3923 | necessary if there is some reason to distinguish | |
3924 | allocs to different slabs, especially in hardened | |
3925 | environments where the risk of heap overflows and | |
3926 | layout control by attackers can usually be | |
3927 | frustrated by disabling merging. This will reduce | |
3928 | most of the exposure of a heap attack to a single | |
3929 | cache (risks via metadata attacks are mostly | |
3930 | unchanged). Debug options disable merging on their | |
3931 | own. | |
3932 | For more information see Documentation/vm/slub.rst. | |
3933 | ||
3934 | slab_max_order= [MM, SLAB] | |
3935 | Determines the maximum allowed order for slabs. | |
3936 | A high setting may cause OOMs due to memory | |
3937 | fragmentation. Defaults to 1 for systems with | |
3938 | more than 32MB of RAM, 0 otherwise. | |
3939 | ||
3940 | slub_debug[=options[,slabs]] [MM, SLUB] | |
3941 | Enabling slub_debug allows one to determine the | |
3942 | culprit if slab objects become corrupted. Enabling | |
3943 | slub_debug can create guard zones around objects and | |
3944 | may poison objects when not in use. Also tracks the | |
3945 | last alloc / free. For more information see | |
3946 | Documentation/vm/slub.rst. | |
3947 | ||
3948 | slub_memcg_sysfs= [MM, SLUB] | |
3949 | Determines whether to enable sysfs directories for | |
3950 | memory cgroup sub-caches. 1 to enable, 0 to disable. | |
3951 | The default is determined by CONFIG_SLUB_MEMCG_SYSFS_ON. | |
3952 | Enabling this can lead to a very high number of debug | |
3953 | directories and files being created under | |
3954 | /sys/kernel/slub. | |
3955 | ||
3956 | slub_max_order= [MM, SLUB] | |
3957 | Determines the maximum allowed order for slabs. | |
3958 | A high setting may cause OOMs due to memory | |
3959 | fragmentation. For more information see | |
3960 | Documentation/vm/slub.rst. | |
3961 | ||
3962 | slub_min_objects= [MM, SLUB] | |
3963 | The minimum number of objects per slab. SLUB will | |
3964 | increase the slab order up to slub_max_order to | |
3965 | generate a sufficiently large slab able to contain | |
3966 | the number of objects indicated. The higher the number | |
3967 | of objects the smaller the overhead of tracking slabs | |
3968 | and the less frequently locks need to be acquired. | |
3969 | For more information see Documentation/vm/slub.rst. | |
3970 | ||
3971 | slub_min_order= [MM, SLUB] | |
3972 | Determines the minimum page order for slabs. Must be | |
3973 | lower than slub_max_order. | |
3974 | For more information see Documentation/vm/slub.rst. | |
3975 | ||
3976 | slub_nomerge [MM, SLUB] | |
3977 | Same with slab_nomerge. This is supported for legacy. | |
3978 | See slab_nomerge for more information. | |
3979 | ||
3980 | smart2= [HW] | |
3981 | Format: <io1>[,<io2>[,...,<io8>]] | |
3982 | ||
3983 | smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices | |
3984 | smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port | |
3985 | smsc-ircc2.ircc_sir= [HW] SIR base I/O port | |
3986 | smsc-ircc2.ircc_fir= [HW] FIR base I/O port | |
3987 | smsc-ircc2.ircc_irq= [HW] IRQ line | |
3988 | smsc-ircc2.ircc_dma= [HW] DMA channel | |
3989 | smsc-ircc2.ircc_transceiver= [HW] Transceiver type: | |
3990 | 0: Toshiba Satellite 1800 (GP data pin select) | |
3991 | 1: Fast pin select (default) | |
3992 | 2: ATC IRMode | |
3993 | ||
3994 | smt [KNL,S390] Set the maximum number of threads (logical | |
3995 | CPUs) to use per physical CPU on systems capable of | |
3996 | symmetric multithreading (SMT). Will be capped to the | |
3997 | actual hardware limit. | |
3998 | Format: <integer> | |
3999 | Default: -1 (no limit) | |
4000 | ||
4001 | softlockup_panic= | |
4002 | [KNL] Should the soft-lockup detector generate panics. | |
4003 | Format: <integer> | |
4004 | ||
4005 | A nonzero value instructs the soft-lockup detector | |
4006 | to panic the machine when a soft-lockup occurs. This | |
4007 | is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC | |
4008 | which is the respective build-time switch to that | |
4009 | functionality. | |
4010 | ||
4011 | softlockup_all_cpu_backtrace= | |
4012 | [KNL] Should the soft-lockup detector generate | |
4013 | backtraces on all cpus. | |
4014 | Format: <integer> | |
4015 | ||
4016 | sonypi.*= [HW] Sony Programmable I/O Control Device driver | |
4017 | See Documentation/laptops/sonypi.txt | |
4018 | ||
4019 | spectre_v2= [X86] Control mitigation of Spectre variant 2 | |
4020 | (indirect branch speculation) vulnerability. | |
4021 | ||
4022 | on - unconditionally enable | |
4023 | off - unconditionally disable | |
4024 | auto - kernel detects whether your CPU model is | |
4025 | vulnerable | |
4026 | ||
4027 | Selecting 'on' will, and 'auto' may, choose a | |
4028 | mitigation method at run time according to the | |
4029 | CPU, the available microcode, the setting of the | |
4030 | CONFIG_RETPOLINE configuration option, and the | |
4031 | compiler with which the kernel was built. | |
4032 | ||
4033 | Specific mitigations can also be selected manually: | |
4034 | ||
4035 | retpoline - replace indirect branches | |
4036 | retpoline,generic - google's original retpoline | |
4037 | retpoline,amd - AMD-specific minimal thunk | |
4038 | ||
4039 | Not specifying this option is equivalent to | |
4040 | spectre_v2=auto. | |
4041 | ||
4042 | spec_store_bypass_disable= | |
4043 | [HW] Control Speculative Store Bypass (SSB) Disable mitigation | |
4044 | (Speculative Store Bypass vulnerability) | |
4045 | ||
4046 | Certain CPUs are vulnerable to an exploit against a | |
4047 | a common industry wide performance optimization known | |
4048 | as "Speculative Store Bypass" in which recent stores | |
4049 | to the same memory location may not be observed by | |
4050 | later loads during speculative execution. The idea | |
4051 | is that such stores are unlikely and that they can | |
4052 | be detected prior to instruction retirement at the | |
4053 | end of a particular speculation execution window. | |
4054 | ||
4055 | In vulnerable processors, the speculatively forwarded | |
4056 | store can be used in a cache side channel attack, for | |
4057 | example to read memory to which the attacker does not | |
4058 | directly have access (e.g. inside sandboxed code). | |
4059 | ||
4060 | This parameter controls whether the Speculative Store | |
4061 | Bypass optimization is used. | |
4062 | ||
4063 | on - Unconditionally disable Speculative Store Bypass | |
4064 | off - Unconditionally enable Speculative Store Bypass | |
4065 | auto - Kernel detects whether the CPU model contains an | |
4066 | implementation of Speculative Store Bypass and | |
4067 | picks the most appropriate mitigation. If the | |
4068 | CPU is not vulnerable, "off" is selected. If the | |
4069 | CPU is vulnerable the default mitigation is | |
4070 | architecture and Kconfig dependent. See below. | |
4071 | prctl - Control Speculative Store Bypass per thread | |
4072 | via prctl. Speculative Store Bypass is enabled | |
4073 | for a process by default. The state of the control | |
4074 | is inherited on fork. | |
4075 | seccomp - Same as "prctl" above, but all seccomp threads | |
4076 | will disable SSB unless they explicitly opt out. | |
4077 | ||
4078 | Not specifying this option is equivalent to | |
4079 | spec_store_bypass_disable=auto. | |
4080 | ||
4081 | Default mitigations: | |
4082 | X86: If CONFIG_SECCOMP=y "seccomp", otherwise "prctl" | |
4083 | ||
4084 | spia_io_base= [HW,MTD] | |
4085 | spia_fio_base= | |
4086 | spia_pedr= | |
4087 | spia_peddr= | |
4088 | ||
4089 | srcutree.counter_wrap_check [KNL] | |
4090 | Specifies how frequently to check for | |
4091 | grace-period sequence counter wrap for the | |
4092 | srcu_data structure's ->srcu_gp_seq_needed field. | |
4093 | The greater the number of bits set in this kernel | |
4094 | parameter, the less frequently counter wrap will | |
4095 | be checked for. Note that the bottom two bits | |
4096 | are ignored. | |
4097 | ||
4098 | srcutree.exp_holdoff [KNL] | |
4099 | Specifies how many nanoseconds must elapse | |
4100 | since the end of the last SRCU grace period for | |
4101 | a given srcu_struct until the next normal SRCU | |
4102 | grace period will be considered for automatic | |
4103 | expediting. Set to zero to disable automatic | |
4104 | expediting. | |
4105 | ||
4106 | ssbd= [ARM64,HW] | |
4107 | Speculative Store Bypass Disable control | |
4108 | ||
4109 | On CPUs that are vulnerable to the Speculative | |
4110 | Store Bypass vulnerability and offer a | |
4111 | firmware based mitigation, this parameter | |
4112 | indicates how the mitigation should be used: | |
4113 | ||
4114 | force-on: Unconditionally enable mitigation for | |
4115 | for both kernel and userspace | |
4116 | force-off: Unconditionally disable mitigation for | |
4117 | for both kernel and userspace | |
4118 | kernel: Always enable mitigation in the | |
4119 | kernel, and offer a prctl interface | |
4120 | to allow userspace to register its | |
4121 | interest in being mitigated too. | |
4122 | ||
4123 | stack_guard_gap= [MM] | |
4124 | override the default stack gap protection. The value | |
4125 | is in page units and it defines how many pages prior | |
4126 | to (for stacks growing down) resp. after (for stacks | |
4127 | growing up) the main stack are reserved for no other | |
4128 | mapping. Default value is 256 pages. | |
4129 | ||
4130 | stacktrace [FTRACE] | |
4131 | Enabled the stack tracer on boot up. | |
4132 | ||
4133 | stacktrace_filter=[function-list] | |
4134 | [FTRACE] Limit the functions that the stack tracer | |
4135 | will trace at boot up. function-list is a comma separated | |
4136 | list of functions. This list can be changed at run | |
4137 | time by the stack_trace_filter file in the debugfs | |
4138 | tracing directory. Note, this enables stack tracing | |
4139 | and the stacktrace above is not needed. | |
4140 | ||
4141 | sti= [PARISC,HW] | |
4142 | Format: <num> | |
4143 | Set the STI (builtin display/keyboard on the HP-PARISC | |
4144 | machines) console (graphic card) which should be used | |
4145 | as the initial boot-console. | |
4146 | See also comment in drivers/video/console/sticore.c. | |
4147 | ||
4148 | sti_font= [HW] | |
4149 | See comment in drivers/video/console/sticore.c. | |
4150 | ||
4151 | stifb= [HW] | |
4152 | Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] | |
4153 | ||
4154 | sunrpc.min_resvport= | |
4155 | sunrpc.max_resvport= | |
4156 | [NFS,SUNRPC] | |
4157 | SunRPC servers often require that client requests | |
4158 | originate from a privileged port (i.e. a port in the | |
4159 | range 0 < portnr < 1024). | |
4160 | An administrator who wishes to reserve some of these | |
4161 | ports for other uses may adjust the range that the | |
4162 | kernel's sunrpc client considers to be privileged | |
4163 | using these two parameters to set the minimum and | |
4164 | maximum port values. | |
4165 | ||
4166 | sunrpc.svc_rpc_per_connection_limit= | |
4167 | [NFS,SUNRPC] | |
4168 | Limit the number of requests that the server will | |
4169 | process in parallel from a single connection. | |
4170 | The default value is 0 (no limit). | |
4171 | ||
4172 | sunrpc.pool_mode= | |
4173 | [NFS] | |
4174 | Control how the NFS server code allocates CPUs to | |
4175 | service thread pools. Depending on how many NICs | |
4176 | you have and where their interrupts are bound, this | |
4177 | option will affect which CPUs will do NFS serving. | |
4178 | Note: this parameter cannot be changed while the | |
4179 | NFS server is running. | |
4180 | ||
4181 | auto the server chooses an appropriate mode | |
4182 | automatically using heuristics | |
4183 | global a single global pool contains all CPUs | |
4184 | percpu one pool for each CPU | |
4185 | pernode one pool for each NUMA node (equivalent | |
4186 | to global on non-NUMA machines) | |
4187 | ||
4188 | sunrpc.tcp_slot_table_entries= | |
4189 | sunrpc.udp_slot_table_entries= | |
4190 | [NFS,SUNRPC] | |
4191 | Sets the upper limit on the number of simultaneous | |
4192 | RPC calls that can be sent from the client to a | |
4193 | server. Increasing these values may allow you to | |
4194 | improve throughput, but will also increase the | |
4195 | amount of memory reserved for use by the client. | |
4196 | ||
4197 | suspend.pm_test_delay= | |
4198 | [SUSPEND] | |
4199 | Sets the number of seconds to remain in a suspend test | |
4200 | mode before resuming the system (see | |
4201 | /sys/power/pm_test). Only available when CONFIG_PM_DEBUG | |
4202 | is set. Default value is 5. | |
4203 | ||
4204 | swapaccount=[0|1] | |
4205 | [KNL] Enable accounting of swap in memory resource | |
4206 | controller if no parameter or 1 is given or disable | |
4207 | it if 0 is given (See Documentation/cgroup-v1/memory.txt) | |
4208 | ||
4209 | swiotlb= [ARM,IA-64,PPC,MIPS,X86] | |
4210 | Format: { <int> | force | noforce } | |
4211 | <int> -- Number of I/O TLB slabs | |
4212 | force -- force using of bounce buffers even if they | |
4213 | wouldn't be automatically used by the kernel | |
4214 | noforce -- Never use bounce buffers (for debugging) | |
4215 | ||
4216 | switches= [HW,M68k] | |
4217 | ||
4218 | sysfs.deprecated=0|1 [KNL] | |
4219 | Enable/disable old style sysfs layout for old udev | |
4220 | on older distributions. When this option is enabled | |
4221 | very new udev will not work anymore. When this option | |
4222 | is disabled (or CONFIG_SYSFS_DEPRECATED not compiled) | |
4223 | in older udev will not work anymore. | |
4224 | Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in | |
4225 | the kernel configuration. | |
4226 | ||
4227 | sysrq_always_enabled | |
4228 | [KNL] | |
4229 | Ignore sysrq setting - this boot parameter will | |
4230 | neutralize any effect of /proc/sys/kernel/sysrq. | |
4231 | Useful for debugging. | |
4232 | ||
4233 | tcpmhash_entries= [KNL,NET] | |
4234 | Set the number of tcp_metrics_hash slots. | |
4235 | Default value is 8192 or 16384 depending on total | |
4236 | ram pages. This is used to specify the TCP metrics | |
4237 | cache size. See Documentation/networking/ip-sysctl.txt | |
4238 | "tcp_no_metrics_save" section for more details. | |
4239 | ||
4240 | tdfx= [HW,DRM] | |
4241 | ||
4242 | test_suspend= [SUSPEND][,N] | |
4243 | Specify "mem" (for Suspend-to-RAM) or "standby" (for | |
4244 | standby suspend) or "freeze" (for suspend type freeze) | |
4245 | as the system sleep state during system startup with | |
4246 | the optional capability to repeat N number of times. | |
4247 | The system is woken from this state using a | |
4248 | wakeup-capable RTC alarm. | |
4249 | ||
4250 | thash_entries= [KNL,NET] | |
4251 | Set number of hash buckets for TCP connection | |
4252 | ||
4253 | thermal.act= [HW,ACPI] | |
4254 | -1: disable all active trip points in all thermal zones | |
4255 | <degrees C>: override all lowest active trip points | |
4256 | ||
4257 | thermal.crt= [HW,ACPI] | |
4258 | -1: disable all critical trip points in all thermal zones | |
4259 | <degrees C>: override all critical trip points | |
4260 | ||
4261 | thermal.nocrt= [HW,ACPI] | |
4262 | Set to disable actions on ACPI thermal zone | |
4263 | critical and hot trip points. | |
4264 | ||
4265 | thermal.off= [HW,ACPI] | |
4266 | 1: disable ACPI thermal control | |
4267 | ||
4268 | thermal.psv= [HW,ACPI] | |
4269 | -1: disable all passive trip points | |
4270 | <degrees C>: override all passive trip points to this | |
4271 | value | |
4272 | ||
4273 | thermal.tzp= [HW,ACPI] | |
4274 | Specify global default ACPI thermal zone polling rate | |
4275 | <deci-seconds>: poll all this frequency | |
4276 | 0: no polling (default) | |
4277 | ||
4278 | threadirqs [KNL] | |
4279 | Force threading of all interrupt handlers except those | |
4280 | marked explicitly IRQF_NO_THREAD. | |
4281 | ||
4282 | tmem [KNL,XEN] | |
4283 | Enable the Transcendent memory driver if built-in. | |
4284 | ||
4285 | tmem.cleancache=0|1 [KNL, XEN] | |
4286 | Default is on (1). Disable the usage of the cleancache | |
4287 | API to send anonymous pages to the hypervisor. | |
4288 | ||
4289 | tmem.frontswap=0|1 [KNL, XEN] | |
4290 | Default is on (1). Disable the usage of the frontswap | |
4291 | API to send swap pages to the hypervisor. If disabled | |
4292 | the selfballooning and selfshrinking are force disabled. | |
4293 | ||
4294 | tmem.selfballooning=0|1 [KNL, XEN] | |
4295 | Default is on (1). Disable the driving of swap pages | |
4296 | to the hypervisor. | |
4297 | ||
4298 | tmem.selfshrinking=0|1 [KNL, XEN] | |
4299 | Default is on (1). Partial swapoff that immediately | |
4300 | transfers pages from Xen hypervisor back to the | |
4301 | kernel based on different criteria. | |
4302 | ||
4303 | topology= [S390] | |
4304 | Format: {off | on} | |
4305 | Specify if the kernel should make use of the cpu | |
4306 | topology information if the hardware supports this. | |
4307 | The scheduler will make use of this information and | |
4308 | e.g. base its process migration decisions on it. | |
4309 | Default is on. | |
4310 | ||
4311 | topology_updates= [KNL, PPC, NUMA] | |
4312 | Format: {off} | |
4313 | Specify if the kernel should ignore (off) | |
4314 | topology updates sent by the hypervisor to this | |
4315 | LPAR. | |
4316 | ||
4317 | tp720= [HW,PS2] | |
4318 | ||
4319 | tpm_suspend_pcr=[HW,TPM] | |
4320 | Format: integer pcr id | |
4321 | Specify that at suspend time, the tpm driver | |
4322 | should extend the specified pcr with zeros, | |
4323 | as a workaround for some chips which fail to | |
4324 | flush the last written pcr on TPM_SaveState. | |
4325 | This will guarantee that all the other pcrs | |
4326 | are saved. | |
4327 | ||
4328 | trace_buf_size=nn[KMG] | |
4329 | [FTRACE] will set tracing buffer size on each cpu. | |
4330 | ||
4331 | trace_event=[event-list] | |
4332 | [FTRACE] Set and start specified trace events in order | |
4333 | to facilitate early boot debugging. The event-list is a | |
4334 | comma separated list of trace events to enable. See | |
4335 | also Documentation/trace/events.rst | |
4336 | ||
4337 | trace_options=[option-list] | |
4338 | [FTRACE] Enable or disable tracer options at boot. | |
4339 | The option-list is a comma delimited list of options | |
4340 | that can be enabled or disabled just as if you were | |
4341 | to echo the option name into | |
4342 | ||
4343 | /sys/kernel/debug/tracing/trace_options | |
4344 | ||
4345 | For example, to enable stacktrace option (to dump the | |
4346 | stack trace of each event), add to the command line: | |
4347 | ||
4348 | trace_options=stacktrace | |
4349 | ||
4350 | See also Documentation/trace/ftrace.rst "trace options" | |
4351 | section. | |
4352 | ||
4353 | tp_printk[FTRACE] | |
4354 | Have the tracepoints sent to printk as well as the | |
4355 | tracing ring buffer. This is useful for early boot up | |
4356 | where the system hangs or reboots and does not give the | |
4357 | option for reading the tracing buffer or performing a | |
4358 | ftrace_dump_on_oops. | |
4359 | ||
4360 | To turn off having tracepoints sent to printk, | |
4361 | echo 0 > /proc/sys/kernel/tracepoint_printk | |
4362 | Note, echoing 1 into this file without the | |
4363 | tracepoint_printk kernel cmdline option has no effect. | |
4364 | ||
4365 | ** CAUTION ** | |
4366 | ||
4367 | Having tracepoints sent to printk() and activating high | |
4368 | frequency tracepoints such as irq or sched, can cause | |
4369 | the system to live lock. | |
4370 | ||
4371 | traceoff_on_warning | |
4372 | [FTRACE] enable this option to disable tracing when a | |
4373 | warning is hit. This turns off "tracing_on". Tracing can | |
4374 | be enabled again by echoing '1' into the "tracing_on" | |
4375 | file located in /sys/kernel/debug/tracing/ | |
4376 | ||
4377 | This option is useful, as it disables the trace before | |
4378 | the WARNING dump is called, which prevents the trace to | |
4379 | be filled with content caused by the warning output. | |
4380 | ||
4381 | This option can also be set at run time via the sysctl | |
4382 | option: kernel/traceoff_on_warning | |
4383 | ||
4384 | transparent_hugepage= | |
4385 | [KNL] | |
4386 | Format: [always|madvise|never] | |
4387 | Can be used to control the default behavior of the system | |
4388 | with respect to transparent hugepages. | |
4389 | See Documentation/admin-guide/mm/transhuge.rst | |
4390 | for more details. | |
4391 | ||
4392 | tsc= Disable clocksource stability checks for TSC. | |
4393 | Format: <string> | |
4394 | [x86] reliable: mark tsc clocksource as reliable, this | |
4395 | disables clocksource verification at runtime, as well | |
4396 | as the stability checks done at bootup. Used to enable | |
4397 | high-resolution timer mode on older hardware, and in | |
4398 | virtualized environment. | |
4399 | [x86] noirqtime: Do not use TSC to do irq accounting. | |
4400 | Used to run time disable IRQ_TIME_ACCOUNTING on any | |
4401 | platforms where RDTSC is slow and this accounting | |
4402 | can add overhead. | |
4403 | [x86] unstable: mark the TSC clocksource as unstable, this | |
4404 | marks the TSC unconditionally unstable at bootup and | |
4405 | avoids any further wobbles once the TSC watchdog notices. | |
4406 | ||
4407 | turbografx.map[2|3]= [HW,JOY] | |
4408 | TurboGraFX parallel port interface | |
4409 | Format: | |
4410 | <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> | |
4411 | See also Documentation/input/devices/joystick-parport.rst | |
4412 | ||
4413 | udbg-immortal [PPC] When debugging early kernel crashes that | |
4414 | happen after console_init() and before a proper | |
4415 | console driver takes over, this boot options might | |
4416 | help "seeing" what's going on. | |
4417 | ||
4418 | uhash_entries= [KNL,NET] | |
4419 | Set number of hash buckets for UDP/UDP-Lite connections | |
4420 | ||
4421 | uhci-hcd.ignore_oc= | |
4422 | [USB] Ignore overcurrent events (default N). | |
4423 | Some badly-designed motherboards generate lots of | |
4424 | bogus events, for ports that aren't wired to | |
4425 | anything. Set this parameter to avoid log spamming. | |
4426 | Note that genuine overcurrent events won't be | |
4427 | reported either. | |
4428 | ||
4429 | unknown_nmi_panic | |
4430 | [X86] Cause panic on unknown NMI. | |
4431 | ||
4432 | usbcore.authorized_default= | |
4433 | [USB] Default USB device authorization: | |
4434 | (default -1 = authorized except for wireless USB, | |
4435 | 0 = not authorized, 1 = authorized) | |
4436 | ||
4437 | usbcore.autosuspend= | |
4438 | [USB] The autosuspend time delay (in seconds) used | |
4439 | for newly-detected USB devices (default 2). This | |
4440 | is the time required before an idle device will be | |
4441 | autosuspended. Devices for which the delay is set | |
4442 | to a negative value won't be autosuspended at all. | |
4443 | ||
4444 | usbcore.usbfs_snoop= | |
4445 | [USB] Set to log all usbfs traffic (default 0 = off). | |
4446 | ||
4447 | usbcore.usbfs_snoop_max= | |
4448 | [USB] Maximum number of bytes to snoop in each URB | |
4449 | (default = 65536). | |
4450 | ||
4451 | usbcore.blinkenlights= | |
4452 | [USB] Set to cycle leds on hubs (default 0 = off). | |
4453 | ||
4454 | usbcore.old_scheme_first= | |
4455 | [USB] Start with the old device initialization | |
4456 | scheme (default 0 = off). | |
4457 | ||
4458 | usbcore.usbfs_memory_mb= | |
4459 | [USB] Memory limit (in MB) for buffers allocated by | |
4460 | usbfs (default = 16, 0 = max = 2047). | |
4461 | ||
4462 | usbcore.use_both_schemes= | |
4463 | [USB] Try the other device initialization scheme | |
4464 | if the first one fails (default 1 = enabled). | |
4465 | ||
4466 | usbcore.initial_descriptor_timeout= | |
4467 | [USB] Specifies timeout for the initial 64-byte | |
4468 | USB_REQ_GET_DESCRIPTOR request in milliseconds | |
4469 | (default 5000 = 5.0 seconds). | |
4470 | ||
4471 | usbcore.nousb [USB] Disable the USB subsystem | |
4472 | ||
4473 | usbcore.quirks= | |
4474 | [USB] A list of quirk entries to augment the built-in | |
4475 | usb core quirk list. List entries are separated by | |
4476 | commas. Each entry has the form | |
4477 | VendorID:ProductID:Flags. The IDs are 4-digit hex | |
4478 | numbers and Flags is a set of letters. Each letter | |
4479 | will change the built-in quirk; setting it if it is | |
4480 | clear and clearing it if it is set. The letters have | |
4481 | the following meanings: | |
4482 | a = USB_QUIRK_STRING_FETCH_255 (string | |
4483 | descriptors must not be fetched using | |
4484 | a 255-byte read); | |
4485 | b = USB_QUIRK_RESET_RESUME (device can't resume | |
4486 | correctly so reset it instead); | |
4487 | c = USB_QUIRK_NO_SET_INTF (device can't handle | |
4488 | Set-Interface requests); | |
4489 | d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't | |
4490 | handle its Configuration or Interface | |
4491 | strings); | |
4492 | e = USB_QUIRK_RESET (device can't be reset | |
4493 | (e.g morph devices), don't use reset); | |
4494 | f = USB_QUIRK_HONOR_BNUMINTERFACES (device has | |
4495 | more interface descriptions than the | |
4496 | bNumInterfaces count, and can't handle | |
4497 | talking to these interfaces); | |
4498 | g = USB_QUIRK_DELAY_INIT (device needs a pause | |
4499 | during initialization, after we read | |
4500 | the device descriptor); | |
4501 | h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For | |
4502 | high speed and super speed interrupt | |
4503 | endpoints, the USB 2.0 and USB 3.0 spec | |
4504 | require the interval in microframes (1 | |
4505 | microframe = 125 microseconds) to be | |
4506 | calculated as interval = 2 ^ | |
4507 | (bInterval-1). | |
4508 | Devices with this quirk report their | |
4509 | bInterval as the result of this | |
4510 | calculation instead of the exponent | |
4511 | variable used in the calculation); | |
4512 | i = USB_QUIRK_DEVICE_QUALIFIER (device can't | |
4513 | handle device_qualifier descriptor | |
4514 | requests); | |
4515 | j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device | |
4516 | generates spurious wakeup, ignore | |
4517 | remote wakeup capability); | |
4518 | k = USB_QUIRK_NO_LPM (device can't handle Link | |
4519 | Power Management); | |
4520 | l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL | |
4521 | (Device reports its bInterval as linear | |
4522 | frames instead of the USB 2.0 | |
4523 | calculation); | |
4524 | m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs | |
4525 | to be disconnected before suspend to | |
4526 | prevent spurious wakeup); | |
4527 | n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a | |
4528 | pause after every control message); | |
4529 | Example: quirks=0781:5580:bk,0a5c:5834:gij | |
4530 | ||
4531 | usbhid.mousepoll= | |
4532 | [USBHID] The interval which mice are to be polled at. | |
4533 | ||
4534 | usbhid.jspoll= | |
4535 | [USBHID] The interval which joysticks are to be polled at. | |
4536 | ||
4537 | usbhid.kbpoll= | |
4538 | [USBHID] The interval which keyboards are to be polled at. | |
4539 | ||
4540 | usb-storage.delay_use= | |
4541 | [UMS] The delay in seconds before a new device is | |
4542 | scanned for Logical Units (default 1). | |
4543 | ||
4544 | usb-storage.quirks= | |
4545 | [UMS] A list of quirks entries to supplement or | |
4546 | override the built-in unusual_devs list. List | |
4547 | entries are separated by commas. Each entry has | |
4548 | the form VID:PID:Flags where VID and PID are Vendor | |
4549 | and Product ID values (4-digit hex numbers) and | |
4550 | Flags is a set of characters, each corresponding | |
4551 | to a common usb-storage quirk flag as follows: | |
4552 | a = SANE_SENSE (collect more than 18 bytes | |
4553 | of sense data); | |
4554 | b = BAD_SENSE (don't collect more than 18 | |
4555 | bytes of sense data); | |
4556 | c = FIX_CAPACITY (decrease the reported | |
4557 | device capacity by one sector); | |
4558 | d = NO_READ_DISC_INFO (don't use | |
4559 | READ_DISC_INFO command); | |
4560 | e = NO_READ_CAPACITY_16 (don't use | |
4561 | READ_CAPACITY_16 command); | |
4562 | f = NO_REPORT_OPCODES (don't use report opcodes | |
4563 | command, uas only); | |
4564 | g = MAX_SECTORS_240 (don't transfer more than | |
4565 | 240 sectors at a time, uas only); | |
4566 | h = CAPACITY_HEURISTICS (decrease the | |
4567 | reported device capacity by one | |
4568 | sector if the number is odd); | |
4569 | i = IGNORE_DEVICE (don't bind to this | |
4570 | device); | |
4571 | j = NO_REPORT_LUNS (don't use report luns | |
4572 | command, uas only); | |
4573 | l = NOT_LOCKABLE (don't try to lock and | |
4574 | unlock ejectable media); | |
4575 | m = MAX_SECTORS_64 (don't transfer more | |
4576 | than 64 sectors = 32 KB at a time); | |
4577 | n = INITIAL_READ10 (force a retry of the | |
4578 | initial READ(10) command); | |
4579 | o = CAPACITY_OK (accept the capacity | |
4580 | reported by the device); | |
4581 | p = WRITE_CACHE (the device cache is ON | |
4582 | by default); | |
4583 | r = IGNORE_RESIDUE (the device reports | |
4584 | bogus residue values); | |
4585 | s = SINGLE_LUN (the device has only one | |
4586 | Logical Unit); | |
4587 | t = NO_ATA_1X (don't allow ATA(12) and ATA(16) | |
4588 | commands, uas only); | |
4589 | u = IGNORE_UAS (don't bind to the uas driver); | |
4590 | w = NO_WP_DETECT (don't test whether the | |
4591 | medium is write-protected). | |
4592 | y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE | |
4593 | even if the device claims no cache) | |
4594 | Example: quirks=0419:aaf5:rl,0421:0433:rc | |
4595 | ||
4596 | user_debug= [KNL,ARM] | |
4597 | Format: <int> | |
4598 | See arch/arm/Kconfig.debug help text. | |
4599 | 1 - undefined instruction events | |
4600 | 2 - system calls | |
4601 | 4 - invalid data aborts | |
4602 | 8 - SIGSEGV faults | |
4603 | 16 - SIGBUS faults | |
4604 | Example: user_debug=31 | |
4605 | ||
4606 | userpte= | |
4607 | [X86] Flags controlling user PTE allocations. | |
4608 | ||
4609 | nohigh = do not allocate PTE pages in | |
4610 | HIGHMEM regardless of setting | |
4611 | of CONFIG_HIGHPTE. | |
4612 | ||
4613 | vdso= [X86,SH] | |
4614 | On X86_32, this is an alias for vdso32=. Otherwise: | |
4615 | ||
4616 | vdso=1: enable VDSO (the default) | |
4617 | vdso=0: disable VDSO mapping | |
4618 | ||
4619 | vdso32= [X86] Control the 32-bit vDSO | |
4620 | vdso32=1: enable 32-bit VDSO | |
4621 | vdso32=0 or vdso32=2: disable 32-bit VDSO | |
4622 | ||
4623 | See the help text for CONFIG_COMPAT_VDSO for more | |
4624 | details. If CONFIG_COMPAT_VDSO is set, the default is | |
4625 | vdso32=0; otherwise, the default is vdso32=1. | |
4626 | ||
4627 | For compatibility with older kernels, vdso32=2 is an | |
4628 | alias for vdso32=0. | |
4629 | ||
4630 | Try vdso32=0 if you encounter an error that says: | |
4631 | dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! | |
4632 | ||
4633 | vector= [IA-64,SMP] | |
4634 | vector=percpu: enable percpu vector domain | |
4635 | ||
4636 | video= [FB] Frame buffer configuration | |
4637 | See Documentation/fb/modedb.txt. | |
4638 | ||
4639 | video.brightness_switch_enabled= [0,1] | |
4640 | If set to 1, on receiving an ACPI notify event | |
4641 | generated by hotkey, video driver will adjust brightness | |
4642 | level and then send out the event to user space through | |
4643 | the allocated input device; If set to 0, video driver | |
4644 | will only send out the event without touching backlight | |
4645 | brightness level. | |
4646 | default: 1 | |
4647 | ||
4648 | virtio_mmio.device= | |
4649 | [VMMIO] Memory mapped virtio (platform) device. | |
4650 | ||
4651 | <size>@<baseaddr>:<irq>[:<id>] | |
4652 | where: | |
4653 | <size> := size (can use standard suffixes | |
4654 | like K, M and G) | |
4655 | <baseaddr> := physical base address | |
4656 | <irq> := interrupt number (as passed to | |
4657 | request_irq()) | |
4658 | <id> := (optional) platform device id | |
4659 | example: | |
4660 | virtio_mmio.device=1K@0x100b0000:48:7 | |
4661 | ||
4662 | Can be used multiple times for multiple devices. | |
4663 | ||
4664 | vga= [BOOT,X86-32] Select a particular video mode | |
4665 | See Documentation/x86/boot.txt and | |
4666 | Documentation/svga.txt. | |
4667 | Use vga=ask for menu. | |
4668 | This is actually a boot loader parameter; the value is | |
4669 | passed to the kernel using a special protocol. | |
4670 | ||
4671 | vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact | |
4672 | size of <nn>. This can be used to increase the | |
4673 | minimum size (128MB on x86). It can also be used to | |
4674 | decrease the size and leave more room for directly | |
4675 | mapped kernel RAM. | |
4676 | ||
4677 | vmcp_cma=nn[MG] [KNL,S390] | |
4678 | Sets the memory size reserved for contiguous memory | |
4679 | allocations for the vmcp device driver. | |
4680 | ||
4681 | vmhalt= [KNL,S390] Perform z/VM CP command after system halt. | |
4682 | Format: <command> | |
4683 | ||
4684 | vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. | |
4685 | Format: <command> | |
4686 | ||
4687 | vmpoff= [KNL,S390] Perform z/VM CP command after power off. | |
4688 | Format: <command> | |
4689 | ||
4690 | vsyscall= [X86-64] | |
4691 | Controls the behavior of vsyscalls (i.e. calls to | |
4692 | fixed addresses of 0xffffffffff600x00 from legacy | |
4693 | code). Most statically-linked binaries and older | |
4694 | versions of glibc use these calls. Because these | |
4695 | functions are at fixed addresses, they make nice | |
4696 | targets for exploits that can control RIP. | |
4697 | ||
4698 | emulate [default] Vsyscalls turn into traps and are | |
4699 | emulated reasonably safely. | |
4700 | ||
4701 | native Vsyscalls are native syscall instructions. | |
4702 | This is a little bit faster than trapping | |
4703 | and makes a few dynamic recompilers work | |
4704 | better than they would in emulation mode. | |
4705 | It also makes exploits much easier to write. | |
4706 | ||
4707 | none Vsyscalls don't work at all. This makes | |
4708 | them quite hard to use for exploits but | |
4709 | might break your system. | |
4710 | ||
4711 | vt.color= [VT] Default text color. | |
4712 | Format: 0xYX, X = foreground, Y = background. | |
4713 | Default: 0x07 = light gray on black. | |
4714 | ||
4715 | vt.cur_default= [VT] Default cursor shape. | |
4716 | Format: 0xCCBBAA, where AA, BB, and CC are the same as | |
4717 | the parameters of the <Esc>[?A;B;Cc escape sequence; | |
4718 | see VGA-softcursor.txt. Default: 2 = underline. | |
4719 | ||
4720 | vt.default_blu= [VT] | |
4721 | Format: <blue0>,<blue1>,<blue2>,...,<blue15> | |
4722 | Change the default blue palette of the console. | |
4723 | This is a 16-member array composed of values | |
4724 | ranging from 0-255. | |
4725 | ||
4726 | vt.default_grn= [VT] | |
4727 | Format: <green0>,<green1>,<green2>,...,<green15> | |
4728 | Change the default green palette of the console. | |
4729 | This is a 16-member array composed of values | |
4730 | ranging from 0-255. | |
4731 | ||
4732 | vt.default_red= [VT] | |
4733 | Format: <red0>,<red1>,<red2>,...,<red15> | |
4734 | Change the default red palette of the console. | |
4735 | This is a 16-member array composed of values | |
4736 | ranging from 0-255. | |
4737 | ||
4738 | vt.default_utf8= | |
4739 | [VT] | |
4740 | Format=<0|1> | |
4741 | Set system-wide default UTF-8 mode for all tty's. | |
4742 | Default is 1, i.e. UTF-8 mode is enabled for all | |
4743 | newly opened terminals. | |
4744 | ||
4745 | vt.global_cursor_default= | |
4746 | [VT] | |
4747 | Format=<-1|0|1> | |
4748 | Set system-wide default for whether a cursor | |
4749 | is shown on new VTs. Default is -1, | |
4750 | i.e. cursors will be created by default unless | |
4751 | overridden by individual drivers. 0 will hide | |
4752 | cursors, 1 will display them. | |
4753 | ||
4754 | vt.italic= [VT] Default color for italic text; 0-15. | |
4755 | Default: 2 = green. | |
4756 | ||
4757 | vt.underline= [VT] Default color for underlined text; 0-15. | |
4758 | Default: 3 = cyan. | |
4759 | ||
4760 | watchdog timers [HW,WDT] For information on watchdog timers, | |
4761 | see Documentation/watchdog/watchdog-parameters.txt | |
4762 | or other driver-specific files in the | |
4763 | Documentation/watchdog/ directory. | |
4764 | ||
4765 | workqueue.watchdog_thresh= | |
4766 | If CONFIG_WQ_WATCHDOG is configured, workqueue can | |
4767 | warn stall conditions and dump internal state to | |
4768 | help debugging. 0 disables workqueue stall | |
4769 | detection; otherwise, it's the stall threshold | |
4770 | duration in seconds. The default value is 30 and | |
4771 | it can be updated at runtime by writing to the | |
4772 | corresponding sysfs file. | |
4773 | ||
4774 | workqueue.disable_numa | |
4775 | By default, all work items queued to unbound | |
4776 | workqueues are affine to the NUMA nodes they're | |
4777 | issued on, which results in better behavior in | |
4778 | general. If NUMA affinity needs to be disabled for | |
4779 | whatever reason, this option can be used. Note | |
4780 | that this also can be controlled per-workqueue for | |
4781 | workqueues visible under /sys/bus/workqueue/. | |
4782 | ||
4783 | workqueue.power_efficient | |
4784 | Per-cpu workqueues are generally preferred because | |
4785 | they show better performance thanks to cache | |
4786 | locality; unfortunately, per-cpu workqueues tend to | |
4787 | be more power hungry than unbound workqueues. | |
4788 | ||
4789 | Enabling this makes the per-cpu workqueues which | |
4790 | were observed to contribute significantly to power | |
4791 | consumption unbound, leading to measurably lower | |
4792 | power usage at the cost of small performance | |
4793 | overhead. | |
4794 | ||
4795 | The default value of this parameter is determined by | |
4796 | the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. | |
4797 | ||
4798 | workqueue.debug_force_rr_cpu | |
4799 | Workqueue used to implicitly guarantee that work | |
4800 | items queued without explicit CPU specified are put | |
4801 | on the local CPU. This guarantee is no longer true | |
4802 | and while local CPU is still preferred work items | |
4803 | may be put on foreign CPUs. This debug option | |
4804 | forces round-robin CPU selection to flush out | |
4805 | usages which depend on the now broken guarantee. | |
4806 | When enabled, memory and cache locality will be | |
4807 | impacted. | |
4808 | ||
4809 | x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of | |
4810 | default x2apic cluster mode on platforms | |
4811 | supporting x2apic. | |
4812 | ||
4813 | x86_intel_mid_timer= [X86-32,APBT] | |
4814 | Choose timer option for x86 Intel MID platform. | |
4815 | Two valid options are apbt timer only and lapic timer | |
4816 | plus one apbt timer for broadcast timer. | |
4817 | x86_intel_mid_timer=apbt_only | lapic_and_apbt | |
4818 | ||
4819 | xen_512gb_limit [KNL,X86-64,XEN] | |
4820 | Restricts the kernel running paravirtualized under Xen | |
4821 | to use only up to 512 GB of RAM. The reason to do so is | |
4822 | crash analysis tools and Xen tools for doing domain | |
4823 | save/restore/migration must be enabled to handle larger | |
4824 | domains. | |
4825 | ||
4826 | xen_emul_unplug= [HW,X86,XEN] | |
4827 | Unplug Xen emulated devices | |
4828 | Format: [unplug0,][unplug1] | |
4829 | ide-disks -- unplug primary master IDE devices | |
4830 | aux-ide-disks -- unplug non-primary-master IDE devices | |
4831 | nics -- unplug network devices | |
4832 | all -- unplug all emulated devices (NICs and IDE disks) | |
4833 | unnecessary -- unplugging emulated devices is | |
4834 | unnecessary even if the host did not respond to | |
4835 | the unplug protocol | |
4836 | never -- do not unplug even if version check succeeds | |
4837 | ||
4838 | xen_nopvspin [X86,XEN] | |
4839 | Disables the ticketlock slowpath using Xen PV | |
4840 | optimizations. | |
4841 | ||
4842 | xen_nopv [X86] | |
4843 | Disables the PV optimizations forcing the HVM guest to | |
4844 | run as generic HVM guest with no PV drivers. | |
4845 | ||
4846 | xirc2ps_cs= [NET,PCMCIA] | |
4847 | Format: | |
4848 | <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] | |
4849 | ||
4850 | xhci-hcd.quirks [USB,KNL] | |
4851 | A hex value specifying bitmask with supplemental xhci | |
4852 | host controller quirks. Meaning of each bit can be | |
4853 | consulted in header drivers/usb/host/xhci.h. |