diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 162 |
1 files changed, 132 insertions, 30 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb95fad81c79..bdc1f33fd3d1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -703,6 +703,11 @@ cpufreq.off=1 [CPU_FREQ] disable the cpufreq sub-system + cpufreq.default_governor= + [CPU_FREQ] Name of the default cpufreq governor or + policy to use. This governor must be registered in the + kernel before the cpufreq driver probes. + cpu_init_udelay=N [X86] Delay for N microsec between assert and de-assert of APIC INIT to start processors. This delay occurs @@ -719,7 +724,7 @@ memory region [offset, offset + size] for that kernel image. If '@offset' is omitted, then a suitable offset is selected automatically. - [KNL, x86_64] select a region under 4G first, and + [KNL, X86-64] Select a region under 4G first, and fall back to reserve region above 4G when '@offset' hasn't been specified. See Documentation/admin-guide/kdump/kdump.rst for further details. @@ -732,14 +737,14 @@ Documentation/admin-guide/kdump/kdump.rst for an example. crashkernel=size[KMG],high - [KNL, x86_64] range could be above 4G. Allow kernel + [KNL, X86-64] range could be above 4G. Allow kernel to allocate physical memory region from top, so could be above 4G if system have more than 4G ram installed. Otherwise memory region will be allocated below 4G, if available. It will be ignored if crashkernel=X is specified. crashkernel=size[KMG],low - [KNL, x86_64] range under 4G. When crashkernel=X,high + [KNL, X86-64] range under 4G. When crashkernel=X,high is passed, kernel could allocate physical memory region above 4G, that cause second kernel crash on system that require some amount of low memory, e.g. swiotlb @@ -827,6 +832,21 @@ useful to also enable the page_owner functionality. on: enable the feature + debugfs= [KNL] This parameter enables what is exposed to userspace + and debugfs internal clients. + Format: { on, no-mount, off } + on: All functions are enabled. + no-mount: + Filesystem is not registered but kernel clients can + access APIs and a crashkernel can be used to read + its content. There is nothing to mount. + off: Filesystem is not registered and clients + get a -EPERM as result when trying to register files + or directories within debugfs. + This is equivalent of the runtime functionality if + debugfs was not enabled in the kernel at all. + Default value is set in build-time with a kernel configuration. + debugpat [X86] Enable PAT debugging decnet.addr= [HW,NET] @@ -896,6 +916,10 @@ disable_radix [PPC] Disable RADIX MMU mode on POWER9 + radix_hcall_invalidate=on [PPC/PSERIES] + Disable RADIX GTSE feature and use hcall for TLB + invalidate. + disable_tlbie [PPC] Disable TLBIE instruction. Currently does not work with KVM, with HASH MMU, or with coherent accelerators. @@ -1207,26 +1231,28 @@ Format: {"off" | "on" | "skip[mbr]"} efi= [EFI] - Format: { "old_map", "nochunk", "noruntime", "debug", - "nosoftreserve", "disable_early_pci_dma", - "no_disable_early_pci_dma" } - old_map [X86-64]: switch to the old ioremap-based EFI - runtime services mapping. [Needs CONFIG_X86_UV=y] + Format: { "debug", "disable_early_pci_dma", + "nochunk", "noruntime", "nosoftreserve", + "novamap", "no_disable_early_pci_dma", + "old_map" } + debug: enable misc debug output. + disable_early_pci_dma: disable the busmaster bit on all + PCI bridges while in the EFI boot stub. nochunk: disable reading files in "chunks" in the EFI boot stub, as chunking can cause problems with some firmware implementations. noruntime : disable EFI runtime services support - debug: enable misc debug output nosoftreserve: The EFI_MEMORY_SP (Specific Purpose) attribute may cause the kernel to reserve the memory range for a memory mapping driver to claim. Specify efi=nosoftreserve to disable this reservation and treat the memory by its base type (i.e. EFI_CONVENTIONAL_MEMORY / "System RAM"). - disable_early_pci_dma: Disable the busmaster bit on all - PCI bridges while in the EFI boot stub + novamap: do not call SetVirtualAddressMap(). no_disable_early_pci_dma: Leave the busmaster bit set on all PCI bridges while in the EFI boot stub + old_map [X86-64]: switch to the old ioremap-based EFI + runtime services mapping. [Needs CONFIG_X86_UV=y] efi_no_storage_paranoia [EFI; X86] Using this parameter you can use more than 50% of @@ -1401,7 +1427,7 @@ gamma= [HW,DRM] - gart_fix_e820= [X86_64] disable the fix e820 for K8 GART + gart_fix_e820= [X86-64] disable the fix e820 for K8 GART Format: off | on default: on @@ -1788,7 +1814,7 @@ Format: 0 | 1 Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. - init_pkru= [x86] Specify the default memory protection keys rights + init_pkru= [X86] Specify the default memory protection keys rights register contents for all processes. 0x55555554 by default (disallow access to all but pkey 0). Can override in debugfs after boot. @@ -1796,7 +1822,7 @@ inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver Format: <irq> - int_pln_enable [x86] Enable power limit notification interrupt + int_pln_enable [X86] Enable power limit notification interrupt integrity_audit=[IMA] Format: { "0" | "1" } @@ -1814,7 +1840,7 @@ bypassed by not enabling DMAR with this option. In this case, gfx device will use physical address for DMA. - forcedac [x86_64] + forcedac [X86-64] With this option iommu will not optimize to look for io virtual address below 32-bit forcing dual address cycle on pci bus for cards supporting greater @@ -1899,7 +1925,7 @@ strict regions from userspace. relaxed - iommu= [x86] + iommu= [X86] off force noforce @@ -1909,8 +1935,8 @@ merge nomerge soft - pt [x86] - nopt [x86] + pt [X86] + nopt [X86] nobypass [PPC/POWERNV] Disable IOMMU bypass, using IOMMU for PCI devices. @@ -2053,21 +2079,21 @@ iucv= [HW,NET] - ivrs_ioapic [HW,X86_64] + ivrs_ioapic [HW,X86-64] Provide an override to the IOAPIC-ID<->DEVICE-ID mapping provided in the IVRS ACPI table. For example, to map IOAPIC-ID decimal 10 to PCI device 00:14.0 write the parameter as: ivrs_ioapic[10]=00:14.0 - ivrs_hpet [HW,X86_64] + ivrs_hpet [HW,X86-64] Provide an override to the HPET-ID<->DEVICE-ID mapping provided in the IVRS ACPI table. For example, to map HPET-ID decimal 0 to PCI device 00:14.0 write the parameter as: ivrs_hpet[0]=00:14.0 - ivrs_acpihid [HW,X86_64] + ivrs_acpihid [HW,X86-64] Provide an override to the ACPI-HID:UID<->DEVICE-ID mapping provided in the IVRS ACPI table. For example, to map UART-HID:UID AMD0020:0 to @@ -2344,7 +2370,7 @@ lapic [X86-32,APIC] Enable the local APIC even if BIOS disabled it. - lapic= [x86,APIC] "notscdeadline" Do not use TSC deadline + lapic= [X86,APIC] "notscdeadline" Do not use TSC deadline value for LAPIC timer one-shot implementation. Default back to the programmable timer unit in the LAPIC. @@ -2786,7 +2812,7 @@ touchscreen support is not enabled in the mainstream kernel as of 2.6.30, a preliminary port can be found in the "bleeding edge" mini2440 support kernel at - http://repo.or.cz/w/linux-2.6/mini2440.git + https://repo.or.cz/w/linux-2.6/mini2440.git mitigations= [X86,PPC,S390,ARM64] Control optional mitigations for @@ -3079,6 +3105,8 @@ no5lvl [X86-64] Disable 5-level paging mode. Forces kernel to use 4-level paging instead. + nofsgsbase [X86] Disables FSGSBASE instructions. + no_console_suspend [HW] Never suspend the console Disable suspending of consoles during suspend and @@ -3160,12 +3188,12 @@ register save and restore. The kernel will only save legacy floating-point registers on task switch. - nohugeiomap [KNL,x86,PPC] Disable kernel huge I/O mappings. + nohugeiomap [KNL,X86,PPC] Disable kernel huge I/O mappings. nosmt [KNL,S390] Disable symmetric multithreading (SMT). Equivalent to smt=1. - [KNL,x86] Disable symmetric multithreading (SMT). + [KNL,X86] Disable symmetric multithreading (SMT). nosmt=force: Force disable SMT, cannot be undone via the sysfs control file. @@ -3927,7 +3955,7 @@ pt. [PARIDE] See Documentation/admin-guide/blockdev/paride.rst. - pti= [X86_64] Control Page Table Isolation of user and + pti= [X86-64] Control Page Table Isolation of user and kernel address spaces. Disabling this feature removes hardening, but improves performance of system calls and interrupts. @@ -3939,7 +3967,7 @@ Not specifying this option is equivalent to pti=auto. - nopti [X86_64] + nopti [X86-64] Equivalent to pti=off pty.legacy_count= @@ -4038,6 +4066,14 @@ latencies, which will choose a value aligned with the appropriate hardware boundaries. + rcutree.rcu_min_cached_objs= [KNL] + Minimum number of objects which are cached and + maintained per one CPU. Object size is equal + to PAGE_SIZE. The cache allows to reduce the + pressure to page allocator, also it makes the + whole algorithm to behave better in low memory + condition. + rcutree.jiffies_till_first_fqs= [KNL] Set delay from grace-period initialization to first attempt to force quiescent states. @@ -4258,6 +4294,20 @@ Set time (jiffies) between CPU-hotplug operations, or zero to disable CPU-hotplug testing. + rcutorture.read_exit= [KNL] + Set the number of read-then-exit kthreads used + to test the interaction of RCU updaters and + task-exit processing. + + rcutorture.read_exit_burst= [KNL] + The number of times in a given read-then-exit + episode that a set of read-then-exit kthreads + is spawned. + + rcutorture.read_exit_delay= [KNL] + The delay, in seconds, between successive + read-then-exit testing episodes. + rcutorture.shuffle_interval= [KNL] Set task-shuffle interval (s). Shuffling tasks allows some CPUs to go into dyntick-idle mode @@ -4407,6 +4457,45 @@ reboot_cpu is s[mp]#### with #### being the processor to be used for rebooting. + refscale.holdoff= [KNL] + Set test-start holdoff period. The purpose of + this parameter is to delay the start of the + test until boot completes in order to avoid + interference. + + refscale.loops= [KNL] + Set the number of loops over the synchronization + primitive under test. Increasing this number + reduces noise due to loop start/end overhead, + but the default has already reduced the per-pass + noise to a handful of picoseconds on ca. 2020 + x86 laptops. + + refscale.nreaders= [KNL] + Set number of readers. The default value of -1 + selects N, where N is roughly 75% of the number + of CPUs. A value of zero is an interesting choice. + + refscale.nruns= [KNL] + Set number of runs, each of which is dumped onto + the console log. + + refscale.readdelay= [KNL] + Set the read-side critical-section duration, + measured in microseconds. + + refscale.scale_type= [KNL] + Specify the read-protection implementation to test. + + refscale.shutdown= [KNL] + Shut down the system at the end of the performance + test. This defaults to 1 (shut it down) when + rcuperf is built into the kernel and to 0 (leave + it running) when rcuperf is built as a module. + + refscale.verbose= [KNL] + Enable additional printk() statements. + relax_domain_level= [KNL, SMP] Set scheduler's default relax_domain_level. See Documentation/admin-guide/cgroup-v1/cpusets.rst. @@ -4604,7 +4693,7 @@ fragmentation. Defaults to 1 for systems with more than 32MB of RAM, 0 otherwise. - slub_debug[=options[,slabs]] [MM, SLUB] + slub_debug[=options[,slabs][;[options[,slabs]]...] [MM, SLUB] Enabling slub_debug allows one to determine the culprit if slab objects become corrupted. Enabling slub_debug can create guard zones around objects and @@ -5082,6 +5171,13 @@ Prevent the CPU-hotplug component of torturing until after init has spawned. + torture.ftrace_dump_at_shutdown= [KNL] + Dump the ftrace buffer at torture-test shutdown, + even if there were no errors. This can be a + very costly operation when many torture tests + are running concurrently, especially on systems + with rotating-rust storage. + tp720= [HW,PS2] tpm_suspend_pcr=[HW,TPM] @@ -5712,8 +5808,9 @@ panic() code such as dumping handler. xen_nopvspin [X86,XEN] - Disables the ticketlock slowpath using Xen PV - optimizations. + Disables the qspinlock slowpath using Xen PV optimizations. + This parameter is obsoleted by "nopvspin" parameter, which + has equivalent effect for XEN platform. xen_nopv [X86] Disables the PV optimizations forcing the HVM guest to @@ -5739,6 +5836,11 @@ as generic guest with no PV drivers. Currently support XEN HVM, KVM, HYPER_V and VMWARE guest. + nopvspin [X86,XEN,KVM] + Disables the qspinlock slow path using PV optimizations + which allow the hypervisor to 'idle' the guest on lock + contention. + xirc2ps_cs= [NET,PCMCIA] Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] |