|
21 | 21 | strictly ACPI specification compliant.
|
22 | 22 | rsdt -- prefer RSDT over (default) XSDT
|
23 | 23 | copy_dsdt -- copy DSDT to memory
|
| 24 | + nocmcff -- Disable firmware first mode for corrected |
| 25 | + errors. This disables parsing the HEST CMC error |
| 26 | + source to check if firmware has set the FF flag. This |
| 27 | + may result in duplicate corrected error reports. |
24 | 28 | nospcr -- disable console in ACPI SPCR table as
|
25 | 29 | default _serial_ console on ARM64
|
26 | 30 | For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
|
|
405 | 409 | not play well with APC CPU idle - disable it if you have
|
406 | 410 | APC and your system crashes randomly.
|
407 | 411 |
|
| 412 | + apic [APIC,X86-64] Use IO-APIC. Default. |
| 413 | + |
408 | 414 | apic= [APIC,X86,EARLY] Advanced Programmable Interrupt Controller
|
409 | 415 | Change the output verbosity while booting
|
410 | 416 | Format: { quiet (default) | verbose | debug }
|
|
424 | 430 | useful so that a dump capture kernel won't be
|
425 | 431 | shot down by NMI
|
426 | 432 |
|
| 433 | + apicpmtimer Do APIC timer calibration using the pmtimer. Implies |
| 434 | + apicmaintimer. Useful when your PIT timer is totally |
| 435 | + broken. |
| 436 | + |
427 | 437 | autoconf= [IPV6]
|
428 | 438 | See Documentation/networking/ipv6.rst.
|
429 | 439 |
|
|
1726 | 1736 |
|
1727 | 1737 | off: Disable GDS mitigation.
|
1728 | 1738 |
|
| 1739 | + gbpages [X86] Use GB pages for kernel direct mappings. |
| 1740 | + |
1729 | 1741 | gcov_persist= [GCOV] When non-zero (default), profiling data for
|
1730 | 1742 | kernel modules is saved and remains accessible via
|
1731 | 1743 | debugfs, even when the module is unloaded/reloaded.
|
|
2008 | 2020 |
|
2009 | 2021 | idle= [X86,EARLY]
|
2010 | 2022 | Format: idle=poll, idle=halt, idle=nomwait
|
2011 |
| - Poll forces a polling idle loop that can slightly |
2012 |
| - improve the performance of waking up a idle CPU, but |
2013 |
| - will use a lot of power and make the system run hot. |
2014 |
| - Not recommended. |
| 2023 | + |
| 2024 | + idle=poll: Don't do power saving in the idle loop |
| 2025 | + using HLT, but poll for rescheduling event. This will |
| 2026 | + make the CPUs eat a lot more power, but may be useful |
| 2027 | + to get slightly better performance in multiprocessor |
| 2028 | + benchmarks. It also makes some profiling using |
| 2029 | + performance counters more accurate. Please note that |
| 2030 | + on systems with MONITOR/MWAIT support (like Intel |
| 2031 | + EM64T CPUs) this option has no performance advantage |
| 2032 | + over the normal idle loop. It may also interact badly |
| 2033 | + with hyperthreading. |
| 2034 | + |
2015 | 2035 | idle=halt: Halt is forced to be used for CPU idle.
|
2016 | 2036 | In such case C2/C3 won't be used again.
|
| 2037 | + |
2017 | 2038 | idle=nomwait: Disable mwait for CPU C-states
|
2018 | 2039 |
|
2019 | 2040 | idxd.sva= [HW]
|
|
2311 | 2332 | relaxed
|
2312 | 2333 |
|
2313 | 2334 | iommu= [X86,EARLY]
|
| 2335 | + |
2314 | 2336 | off
|
| 2337 | + Don't initialize and use any kind of IOMMU. |
| 2338 | + |
2315 | 2339 | force
|
| 2340 | + Force the use of the hardware IOMMU even when |
| 2341 | + it is not actually needed (e.g. because < 3 GB |
| 2342 | + memory). |
| 2343 | + |
2316 | 2344 | noforce
|
| 2345 | + Don't force hardware IOMMU usage when it is not |
| 2346 | + needed. (default). |
| 2347 | + |
2317 | 2348 | biomerge
|
2318 | 2349 | panic
|
2319 | 2350 | nopanic
|
2320 | 2351 | merge
|
2321 | 2352 | nomerge
|
| 2353 | + |
2322 | 2354 | soft
|
2323 |
| - pt [X86] |
2324 |
| - nopt [X86] |
2325 |
| - nobypass [PPC/POWERNV] |
| 2355 | + Use software bounce buffering (SWIOTLB) (default for |
| 2356 | + Intel machines). This can be used to prevent the usage |
| 2357 | + of an available hardware IOMMU. |
| 2358 | + |
| 2359 | + [X86] |
| 2360 | + pt |
| 2361 | + [X86] |
| 2362 | + nopt |
| 2363 | + [PPC/POWERNV] |
| 2364 | + nobypass |
2326 | 2365 | Disable IOMMU bypass, using IOMMU for PCI devices.
|
2327 | 2366 |
|
| 2367 | + [X86] |
| 2368 | + AMD Gart HW IOMMU-specific options: |
| 2369 | + |
| 2370 | + <size> |
| 2371 | + Set the size of the remapping area in bytes. |
| 2372 | + |
| 2373 | + allowed |
| 2374 | + Overwrite iommu off workarounds for specific chipsets |
| 2375 | + |
| 2376 | + fullflush |
| 2377 | + Flush IOMMU on each allocation (default). |
| 2378 | + |
| 2379 | + nofullflush |
| 2380 | + Don't use IOMMU fullflush. |
| 2381 | + |
| 2382 | + memaper[=<order>] |
| 2383 | + Allocate an own aperture over RAM with size |
| 2384 | + 32MB<<order. (default: order=1, i.e. 64MB) |
| 2385 | + |
| 2386 | + merge |
| 2387 | + Do scatter-gather (SG) merging. Implies "force" |
| 2388 | + (experimental). |
| 2389 | + |
| 2390 | + nomerge |
| 2391 | + Don't do scatter-gather (SG) merging. |
| 2392 | + |
| 2393 | + noaperture |
| 2394 | + Ask the IOMMU not to touch the aperture for AGP. |
| 2395 | + |
| 2396 | + noagp |
| 2397 | + Don't initialize the AGP driver and use full aperture. |
| 2398 | + |
| 2399 | + panic |
| 2400 | + Always panic when IOMMU overflows. |
| 2401 | + |
2328 | 2402 | iommu.forcedac= [ARM64,X86,EARLY] Control IOVA allocation for PCI devices.
|
2329 | 2403 | Format: { "0" | "1" }
|
2330 | 2404 | 0 - Try to allocate a 32-bit DMA address first, before
|
|
2695 | 2769 | VMs, i.e. on the 0=>1 and 1=>0 transitions of the
|
2696 | 2770 | number of VMs.
|
2697 | 2771 |
|
2698 |
| - Enabling virtualization at module lode avoids potential |
| 2772 | + Enabling virtualization at module load avoids potential |
2699 | 2773 | latency for creation of the 0=>1 VM, as KVM serializes
|
2700 | 2774 | virtualization enabling across all online CPUs. The
|
2701 | 2775 | "cost" of enabling virtualization when KVM is loaded,
|
|
3259 | 3333 | devices can be requested on-demand with the
|
3260 | 3334 | /dev/loop-control interface.
|
3261 | 3335 |
|
3262 |
| - mce [X86-32] Machine Check Exception |
| 3336 | + mce= [X86-{32,64}] |
| 3337 | + |
| 3338 | + Please see Documentation/arch/x86/x86_64/machinecheck.rst for sysfs runtime tunables. |
| 3339 | + |
| 3340 | + off |
| 3341 | + disable machine check |
| 3342 | + |
| 3343 | + no_cmci |
| 3344 | + disable CMCI(Corrected Machine Check Interrupt) that |
| 3345 | + Intel processor supports. Usually this disablement is |
| 3346 | + not recommended, but it might be handy if your |
| 3347 | + hardware is misbehaving. |
| 3348 | + |
| 3349 | + Note that you'll get more problems without CMCI than |
| 3350 | + with due to the shared banks, i.e. you might get |
| 3351 | + duplicated error logs. |
| 3352 | + |
| 3353 | + dont_log_ce |
| 3354 | + don't make logs for corrected errors. All events |
| 3355 | + reported as corrected are silently cleared by OS. This |
| 3356 | + option will be useful if you have no interest in any |
| 3357 | + of corrected errors. |
| 3358 | + |
| 3359 | + ignore_ce |
| 3360 | + disable features for corrected errors, e.g. |
| 3361 | + polling timer and CMCI. All events reported as |
| 3362 | + corrected are not cleared by OS and remained in its |
| 3363 | + error banks. |
| 3364 | + |
| 3365 | + Usually this disablement is not recommended, however |
| 3366 | + if there is an agent checking/clearing corrected |
| 3367 | + errors (e.g. BIOS or hardware monitoring |
| 3368 | + applications), conflicting with OS's error handling, |
| 3369 | + and you cannot deactivate the agent, then this option |
| 3370 | + will be a help. |
| 3371 | + |
| 3372 | + no_lmce |
| 3373 | + do not opt-in to Local MCE delivery. Use legacy method |
| 3374 | + to broadcast MCEs. |
| 3375 | + |
| 3376 | + bootlog |
| 3377 | + enable logging of machine checks left over from |
| 3378 | + booting. Disabled by default on AMD Fam10h and older |
| 3379 | + because some BIOS leave bogus ones. |
| 3380 | + |
| 3381 | + If your BIOS doesn't do that it's a good idea to |
| 3382 | + enable though to make sure you log even machine check |
| 3383 | + events that result in a reboot. On Intel systems it is |
| 3384 | + enabled by default. |
| 3385 | + |
| 3386 | + nobootlog |
| 3387 | + disable boot machine check logging. |
| 3388 | + |
| 3389 | + monarchtimeout (number) |
| 3390 | + sets the time in us to wait for other CPUs on machine |
| 3391 | + checks. 0 to disable. |
| 3392 | + |
| 3393 | + bios_cmci_threshold |
| 3394 | + don't overwrite the bios-set CMCI threshold. This boot |
| 3395 | + option prevents Linux from overwriting the CMCI |
| 3396 | + threshold set by the bios. Without this option, Linux |
| 3397 | + always sets the CMCI threshold to 1. Enabling this may |
| 3398 | + make memory predictive failure analysis less effective |
| 3399 | + if the bios sets thresholds for memory errors since we |
| 3400 | + will not see details for all errors. |
| 3401 | + |
| 3402 | + recovery |
| 3403 | + force-enable recoverable machine check code paths |
| 3404 | + |
| 3405 | + Everything else is in sysfs now. |
3263 | 3406 |
|
3264 |
| - mce=option [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst |
3265 | 3407 |
|
3266 | 3408 | md= [HW] RAID subsystems devices and level
|
3267 | 3409 | See Documentation/admin-guide/md.rst.
|
|
3887 | 4029 | noapic [SMP,APIC,EARLY] Tells the kernel to not make use of any
|
3888 | 4030 | IOAPICs that may be present in the system.
|
3889 | 4031 |
|
| 4032 | + noapictimer [APIC,X86] Don't set up the APIC timer |
| 4033 | + |
3890 | 4034 | noautogroup Disable scheduler automatic task group creation.
|
3891 | 4035 |
|
3892 | 4036 | nocache [ARM,EARLY]
|
|
3934 | 4078 | register save and restore. The kernel will only save
|
3935 | 4079 | legacy floating-point registers on task switch.
|
3936 | 4080 |
|
| 4081 | + nogbpages [X86] Do not use GB pages for kernel direct mappings. |
| 4082 | + |
3937 | 4083 | no_hash_pointers
|
3938 | 4084 | [KNL,EARLY]
|
3939 | 4085 | Force pointers printed to the console or buffers to be
|
|
3960 | 4106 | the impact of the sleep instructions. This is also
|
3961 | 4107 | useful when using JTAG debugger.
|
3962 | 4108 |
|
| 4109 | + nohpet [X86] Don't use the HPET timer. |
| 4110 | + |
3963 | 4111 | nohugeiomap [KNL,X86,PPC,ARM64,EARLY] Disable kernel huge I/O mappings.
|
3964 | 4112 |
|
3965 | 4113 | nohugevmalloc [KNL,X86,PPC,ARM64,EARLY] Disable kernel huge vmalloc mappings.
|
|
4111 | 4259 |
|
4112 | 4260 | nosync [HW,M68K] Disables sync negotiation for all devices.
|
4113 | 4261 |
|
4114 |
| - no_timer_check [X86,APIC] Disables the code which tests for |
4115 |
| - broken timer IRQ sources. |
| 4262 | + no_timer_check [X86,APIC] Disables the code which tests for broken |
| 4263 | + timer IRQ sources, i.e., the IO-APIC timer. This can |
| 4264 | + work around problems with incorrect timer |
| 4265 | + initialization on some boards. |
4116 | 4266 |
|
4117 | 4267 | no_uaccess_flush
|
4118 | 4268 | [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
|
|
4192 | 4342 | If given as an integer followed by 'U', it will
|
4193 | 4343 | divide each physical node into N emulated nodes.
|
4194 | 4344 |
|
| 4345 | + numa=noacpi [X86] Don't parse the SRAT table for NUMA setup |
| 4346 | + |
| 4347 | + numa=nohmat [X86] Don't parse the HMAT table for NUMA setup, or |
| 4348 | + soft-reserved memory partitioning. |
| 4349 | + |
4195 | 4350 | numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
|
4196 | 4351 | NUMA balancing.
|
4197 | 4352 | Allowed values are enable and disable
|
|
5715 | 5870 | reboot_cpu is s[mp]#### with #### being the processor
|
5716 | 5871 | to be used for rebooting.
|
5717 | 5872 |
|
| 5873 | + acpi |
| 5874 | + Use the ACPI RESET_REG in the FADT. If ACPI is not |
| 5875 | + configured or the ACPI reset does not work, the reboot |
| 5876 | + path attempts the reset using the keyboard controller. |
| 5877 | + |
| 5878 | + bios |
| 5879 | + Use the CPU reboot vector for warm reset |
| 5880 | + |
| 5881 | + cold |
| 5882 | + Set the cold reboot flag |
| 5883 | + |
| 5884 | + default |
| 5885 | + There are some built-in platform specific "quirks" |
| 5886 | + - you may see: "reboot: <name> series board detected. |
| 5887 | + Selecting <type> for reboots." In the case where you |
| 5888 | + think the quirk is in error (e.g. you have newer BIOS, |
| 5889 | + or newer board) using this option will ignore the |
| 5890 | + built-in quirk table, and use the generic default |
| 5891 | + reboot actions. |
| 5892 | + |
| 5893 | + efi |
| 5894 | + Use efi reset_system runtime service. If EFI is not |
| 5895 | + configured or the EFI reset does not work, the reboot |
| 5896 | + path attempts the reset using the keyboard controller. |
| 5897 | + |
| 5898 | + force |
| 5899 | + Don't stop other CPUs on reboot. This can make reboot |
| 5900 | + more reliable in some cases. |
| 5901 | + |
| 5902 | + kbd |
| 5903 | + Use the keyboard controller. cold reset (default) |
| 5904 | + |
| 5905 | + pci |
| 5906 | + Use a write to the PCI config space register 0xcf9 to |
| 5907 | + trigger reboot. |
| 5908 | + |
| 5909 | + triple |
| 5910 | + Force a triple fault (init) |
| 5911 | + |
| 5912 | + warm |
| 5913 | + Don't set the cold reboot flag |
| 5914 | + |
| 5915 | + Using warm reset will be much faster especially on big |
| 5916 | + memory systems because the BIOS will not go through |
| 5917 | + the memory check. Disadvantage is that not all |
| 5918 | + hardware will be completely reinitialized on reboot so |
| 5919 | + there may be boot problems on some systems. |
| 5920 | + |
| 5921 | + |
5718 | 5922 | refscale.holdoff= [KNL]
|
5719 | 5923 | Set test-start holdoff period. The purpose of
|
5720 | 5924 | this parameter is to delay the start of the
|
|
6106 | 6310 |
|
6107 | 6311 | serialnumber [BUGS=X86-32]
|
6108 | 6312 |
|
6109 |
| - sev=option[,option...] [X86-64] See Documentation/arch/x86/x86_64/boot-options.rst |
| 6313 | + sev=option[,option...] [X86-64] |
| 6314 | + |
| 6315 | + debug |
| 6316 | + Enable debug messages. |
| 6317 | + |
| 6318 | + nosnp |
| 6319 | + Do not enable SEV-SNP (applies to host/hypervisor |
| 6320 | + only). Setting 'nosnp' avoids the RMP check overhead |
| 6321 | + in memory accesses when users do not want to run |
| 6322 | + SEV-SNP guests. |
6110 | 6323 |
|
6111 | 6324 | shapers= [NET]
|
6112 | 6325 | Maximal number of shapers.
|
|
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