diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 343 |
1 files changed, 305 insertions, 38 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 04545725f187..b4ee11198762 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -50,7 +50,7 @@ CONFIG_ACPI_DEBUG must be enabled to produce any ACPI debug output. Bits in debug_layer correspond to a _COMPONENT in an ACPI source file, e.g., - #define _COMPONENT ACPI_PCI_COMPONENT + #define _COMPONENT ACPI_EVENTS Bits in debug_level correspond to a level in ACPI_DEBUG_PRINT statements, e.g., ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... @@ -60,8 +60,6 @@ Enable processor driver info messages: acpi.debug_layer=0x20000000 - Enable PCI/PCI interrupt routing info messages: - acpi.debug_layer=0x400000 Enable AML "Debug" output, i.e., stores to the Debug object while interpreting AML: acpi.debug_layer=0xffffffff acpi.debug_level=0x2 @@ -115,7 +113,7 @@ the GPE dispatcher. This facility can be used to prevent such uncontrolled GPE floodings. - Format: <byte> + Format: <byte> or <bitmap-list> acpi_no_auto_serialize [HW,ACPI] Disable auto-serialization of AML methods @@ -303,6 +301,9 @@ allowed anymore to lift isolation requirements as needed. This option does not override iommu=pt + force_enable - Force enable the IOMMU on platforms known + to be buggy with IOMMU enabled. Use this + option with care. amd_iommu_dump= [HW,X86-64] Enable AMD IOMMU driver option to dump the ACPI table @@ -499,16 +500,21 @@ ccw_timeout_log [S390] See Documentation/s390/common_io.rst for details. - cgroup_disable= [KNL] Disable a particular controller - Format: {name of the controller(s) to disable} + cgroup_disable= [KNL] Disable a particular controller or optional feature + Format: {name of the controller(s) or feature(s) to disable} The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in a single hierarchy - foo isn't visible as an individually mountable subsystem + - if foo is an optional feature then the feature is + disabled and corresponding cgroup files are not + created {Currently only "memory" controller deal with this and cut the overhead, others just disable the usage. So only cgroup_disable=memory is actually worthy} + Specifying "pressure" disables per-cgroup pressure + stall information accounting feature cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1 Format: { { controller | "all" | "named" } @@ -583,6 +589,28 @@ loops can be debugged more effectively on production systems. + clocksource.max_cswd_read_retries= [KNL] + Number of clocksource_watchdog() retries due to + external delays before the clock will be marked + unstable. Defaults to three retries, that is, + four attempts to read the clock under test. + + clocksource.verify_n_cpus= [KNL] + Limit the number of CPUs checked for clocksources + marked with CLOCK_SOURCE_VERIFY_PERCPU that + are marked unstable due to excessive skew. + A negative value says to check all CPUs, while + zero says not to check any. Values larger than + nr_cpu_ids are silently truncated to nr_cpu_ids. + The actual CPUs are chosen randomly, with + no replacement if the same CPU is chosen twice. + + clocksource-wdtest.holdoff= [KNL] + Set the time in seconds that the clocksource + watchdog test waits before commencing its tests. + Defaults to zero when built as a module and to + 10 seconds when built into the kernel. + clearcpuid=BITNUM[,BITNUM...] [X86] Disable CPUID feature X for the kernel. See arch/x86/include/asm/cpufeatures.h for the valid bit @@ -784,6 +812,16 @@ cs89x0_media= [HW,NET] Format: { rj45 | aui | bnc } + csdlock_debug= [KNL] Enable debug add-ons of cross-CPU function call + handling. When switched on, additional debug data is + printed to the console in case a hanging CPU is + detected, and that CPU is pinged again in order to try + to resolve the hang situation. + 0: disable csdlock debugging (default) + 1: enable basic csdlock debugging (minor impact) + ext: enable extended csdlock debugging (more impact, + but more data) + dasd= [HW,NET] See header of drivers/s390/block/dasd_devmap.c. @@ -1461,6 +1499,12 @@ Don't use this when you are not running on the android emulator + gpio-mockup.gpio_mockup_ranges + [HW] Sets the ranges of gpiochip of for this device. + Format: <start1>,<end1>,<start2>,<end2>... + gpio-mockup.gpio_mockup_named_lines + [HW] Let the driver know GPIO lines should be named. + gpt [EFI] Forces disk with valid GPT signature but invalid Protective MBR to be treated as GPT. If the primary GPT is corrupted, it enables the backup/alternate @@ -1484,10 +1528,6 @@ Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. Default: 1024 - gpio-mockup.gpio_mockup_ranges - [HW] Sets the ranges of gpiochip of for this device. - Format: <start1>,<end1>,<start2>,<end2>... - hardlockup_all_cpu_backtrace= [KNL] Should the hard-lockup detector generate backtraces on all cpus. @@ -1557,6 +1597,23 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_free_vmemmap= + [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + enabled. + Allows heavy hugetlb users to free up some more + memory (6 * PAGE_SIZE for each 2MB hugetlb page). + Format: { on | off (default) } + + on: enable the feature + off: disable the feature + + Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y, + the default is on. + + This is not compatible with memory_hotplug.memmap_on_memory. + If both parameters are enabled, hugetlb_free_vmemmap takes + precedence over memory_hotplug.memmap_on_memory. + hung_task_panic= [KNL] Should the hung task detector generate panics. Format: 0 | 1 @@ -1825,6 +1882,18 @@ initcall functions. Useful for debugging built-in modules and initcalls. + initramfs_async= [KNL] + Format: <bool> + Default: 1 + This parameter controls whether the initramfs + image is unpacked asynchronously, concurrently + with devices being probed and + initialized. This should normally just work, + but as a debugging aid, one can get the + historical behaviour of the initramfs + unpacking being completed before device_ and + late_ initcalls. + initrd= [BOOT] Specify the location of the initial ramdisk initrdmem= [KNL] Specify a physical address and size from which to @@ -1869,13 +1938,6 @@ bypassed by not enabling DMAR with this option. In this case, gfx device will use physical address for DMA. - 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 - than 32-bit addressing. The default is to look - for translation below 32-bit and if not available - then look in the higher range. strict [Default Off] With this option on every unmap_single operation will result in a hardware IOTLB flush operation as opposed @@ -1964,7 +2026,15 @@ nobypass [PPC/POWERNV] Disable IOMMU bypass, using IOMMU for PCI devices. - iommu.strict= [ARM64] Configure TLB invalidation behaviour + iommu.forcedac= [ARM64, X86] Control IOVA allocation for PCI devices. + Format: { "0" | "1" } + 0 - Try to allocate a 32-bit DMA address first, before + falling back to the full range if needed. + 1 - Allocate directly from the full usable range, + forcing Dual Address Cycle for PCI cards supporting + greater than 32-bit addressing. + + iommu.strict= [ARM64, X86] Configure TLB invalidation behaviour Format: { "0" | "1" } 0 - Lazy mode. Request that DMA unmap operations use deferred @@ -1975,6 +2045,10 @@ 1 - Strict mode (default). DMA unmap operations invalidate IOMMU hardware TLBs synchronously. + Note: on x86, the default behaviour depends on the + equivalent driver-specific parameters, but a strict + mode explicitly specified by either method takes + precedence. iommu.passthrough= [ARM64, X86] Configure DMA to bypass the IOMMU by default. @@ -2279,8 +2353,7 @@ state is kept private from the host. Not valid if the kernel is running in EL2. - Defaults to VHE/nVHE based on hardware support and - the value of CONFIG_ARM64_VHE. + Defaults to VHE/nVHE based on hardware support. kvm-arm.vgic_v3_group0_trap= [KVM,ARM] Trap guest accesses to GICv3 group-0 @@ -2794,7 +2867,28 @@ seconds. Use this parameter to check at some other rate. 0 disables periodic checking. - memtest= [KNL,X86,ARM,PPC] Enable memtest + memory_hotplug.memmap_on_memory + [KNL,X86,ARM] Boolean flag to enable this feature. + Format: {on | off (default)} + When enabled, runtime hotplugged memory will + allocate its internal metadata (struct pages) + from the hotadded memory which will allow to + hotadd a lot of memory without requiring + additional memory to do so. + This feature is disabled by default because it + has some implication on large (e.g. GB) + allocations in some configurations (e.g. small + memory blocks). + The state of the flag can be read in + /sys/module/memory_hotplug/parameters/memmap_on_memory. + Note that even when enabled, there are a few cases where + the feature is not effective. + + This is not compatible with hugetlb_free_vmemmap. If + both parameters are enabled, hugetlb_free_vmemmap takes + precedence over memory_hotplug.memmap_on_memory. + + memtest= [KNL,X86,ARM,PPC,RISCV] Enable memtest Format: <integer> default : 0 <disable> Specifies the number of memtest passes to be @@ -3205,7 +3299,7 @@ noclflush [BUGS=X86] Don't use the CLFLUSH instruction - nodelayacct [KNL] Disable per-task delay accounting + delayacct [KNL] Enable per-task delay accounting nodsp [SH] Disable hardware DSP at boot time. @@ -3243,6 +3337,8 @@ nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings. + nohugevmalloc [PPC] Disable kernel huge vmalloc mappings. + nosmt [KNL,S390] Disable symmetric multithreading (SMT). Equivalent to smt=1. @@ -3472,7 +3568,11 @@ nr_uarts= [SERIAL] maximum number of UARTs to be registered. - numa_balancing= [KNL,X86] Enable or disable automatic NUMA balancing. + numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only + set up a single NUMA node spanning all memory. + + numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic + NUMA balancing. Allowed values are enable and disable numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. @@ -3524,6 +3624,12 @@ off: turn off poisoning (default) on: turn on poisoning + page_reporting.page_reporting_order= + [KNL] Minimal page reporting order + Format: <integer> + Adjust the minimal page reporting order. The page + reporting is disabled when it exceeds (MAX_ORDER-1). + panic= [KNL] Kernel behaviour on panic: delay <timeout> timeout > 0: seconds before rebooting timeout = 0: wait forever @@ -3592,6 +3698,96 @@ Currently this function knows 686a and 8231 chips. Format: [spp|ps2|epp|ecp|ecpepp] + pata_legacy.all= [HW,LIBATA] + Format: <int> + Set to non-zero to probe primary and secondary ISA + port ranges on PCI systems where no PCI PATA device + has been found at either range. Disabled by default. + + pata_legacy.autospeed= [HW,LIBATA] + Format: <int> + Set to non-zero if a chip is present that snoops speed + changes. Disabled by default. + + pata_legacy.ht6560a= [HW,LIBATA] + Format: <int> + Set to 1, 2, or 3 for HT 6560A on the primary channel, + the secondary channel, or both channels respectively. + Disabled by default. + + pata_legacy.ht6560b= [HW,LIBATA] + Format: <int> + Set to 1, 2, or 3 for HT 6560B on the primary channel, + the secondary channel, or both channels respectively. + Disabled by default. + + pata_legacy.iordy_mask= [HW,LIBATA] + Format: <int> + IORDY enable mask. Set individual bits to allow IORDY + for the respective channel. Bit 0 is for the first + legacy channel handled by this driver, bit 1 is for + the second channel, and so on. The sequence will often + correspond to the primary legacy channel, the secondary + legacy channel, and so on, but the handling of a PCI + bus and the use of other driver options may interfere + with the sequence. By default IORDY is allowed across + all channels. + + pata_legacy.opti82c46x= [HW,LIBATA] + Format: <int> + Set to 1, 2, or 3 for Opti 82c611A on the primary + channel, the secondary channel, or both channels + respectively. Disabled by default. + + pata_legacy.opti82c611a= [HW,LIBATA] + Format: <int> + Set to 1, 2, or 3 for Opti 82c465MV on the primary + channel, the secondary channel, or both channels + respectively. Disabled by default. + + pata_legacy.pio_mask= [HW,LIBATA] + Format: <int> + PIO mode mask for autospeed devices. Set individual + bits to allow the use of the respective PIO modes. + Bit 0 is for mode 0, bit 1 is for mode 1, and so on. + All modes allowed by default. + + pata_legacy.probe_all= [HW,LIBATA] + Format: <int> + Set to non-zero to probe tertiary and further ISA + port ranges on PCI systems. Disabled by default. + + pata_legacy.probe_mask= [HW,LIBATA] + Format: <int> + Probe mask for legacy ISA PATA ports. Depending on + platform configuration and the use of other driver + options up to 6 legacy ports are supported: 0x1f0, + 0x170, 0x1e8, 0x168, 0x1e0, 0x160, however probing + of individual ports can be disabled by setting the + corresponding bits in the mask to 1. Bit 0 is for + the first port in the list above (0x1f0), and so on. + By default all supported ports are probed. + + pata_legacy.qdi= [HW,LIBATA] + Format: <int> + Set to non-zero to probe QDI controllers. By default + set to 1 if CONFIG_PATA_QDI_MODULE, 0 otherwise. + + pata_legacy.winbond= [HW,LIBATA] + Format: <int> + Set to non-zero to probe Winbond controllers. Use + the standard I/O port (0x130) if 1, otherwise the + value given is the I/O port to use (typically 0x1b0). + By default set to 1 if CONFIG_PATA_WINBOND_VLB_MODULE, + 0 otherwise. + + pata_platform.pio_mask= [HW,LIBATA] + Format: <int> + Supported PIO mode mask. Set individual bits to allow + the use of the respective PIO modes. Bit 0 is for + mode 0, bit 1 is for mode 1, and so on. Mode 0 only + allowed by default. + pause_on_oops= Halt all CPUs after the first oops has been printed for the specified number of seconds. This is to be used if @@ -4061,6 +4257,17 @@ fully seed the kernel's CRNG. Default is controlled by CONFIG_RANDOM_TRUST_CPU. + randomize_kstack_offset= + [KNL] Enable or disable kernel stack offset + randomization, which provides roughly 5 bits of + entropy, frustrating memory corruption attacks + that depend on stack address determinism or + cross-syscall address exposures. This is only + available on architectures that have defined + CONFIG_HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET. + Format: <bool> (1/Y/y=enable, 0/N/n=disable) + Default is CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT. + ras=option[,option,...] [KNL] RAS-specific options cec_disable [X86] @@ -4068,9 +4275,7 @@ see CONFIG_RAS_CEC help text. rcu_nocbs= [KNL] - The argument is a cpu list, as described above, - except that the string "all" can be used to - specify every CPU on the system. + The argument is a cpu list, as described above. In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. @@ -4149,6 +4354,11 @@ whole algorithm to behave better in low memory condition. + rcutree.rcu_delay_page_cache_fill_msec= [KNL] + Set the page-cache refill delay (in milliseconds) + in response to low-memory conditions. The range + of permitted values is in the range 0:100000. + rcutree.jiffies_till_first_fqs= [KNL] Set delay from grace-period initialization to first attempt to force quiescent states. @@ -4259,6 +4469,18 @@ rcuscale.kfree_rcu_test= [KNL] Set to measure performance of kfree_rcu() flooding. + rcuscale.kfree_rcu_test_double= [KNL] + Test the double-argument variant of kfree_rcu(). + If this parameter has the same value as + rcuscale.kfree_rcu_test_single, both the single- + and double-argument variants are tested. + + rcuscale.kfree_rcu_test_single= [KNL] + Test the single-argument variant of kfree_rcu(). + If this parameter has the same value as + rcuscale.kfree_rcu_test_double, both the single- + and double-argument variants are tested. + rcuscale.kfree_nthreads= [KNL] The number of threads running loops of kfree_rcu(). @@ -4622,11 +4844,6 @@ Reserves a hole at the top of the kernel virtual address space. - reservelow= [X86] - Format: nn[K] - Set the amount of memory to reserve for BIOS at - the bottom of the address space. - reset_devices [KNL] Force drivers to reset the underlying device during initialization. @@ -4725,7 +4942,7 @@ sbni= [NET] Granch SBNI12 leased line adapter - sched_debug [KNL] Enables verbose scheduler debug messages. + sched_verbose [KNL] Enables verbose scheduler debug messages. schedstats= [KNL,X86] Enable or disable scheduled statistics. Allowed values are enable and disable. This feature @@ -4877,6 +5094,10 @@ slram= [HW,MTD] + slab_merge [MM] + Enable merging of slabs with similar size when the + kernel is built without CONFIG_SLAB_MERGE_DEFAULT. + slab_nomerge [MM] Disable merging of slabs with similar size. May be necessary if there is some reason to distinguish @@ -4924,6 +5145,9 @@ lower than slub_max_order. For more information see Documentation/vm/slub.rst. + slub_merge [MM, SLUB] + Same with slab_merge. + slub_nomerge [MM, SLUB] Same with slab_nomerge. This is supported for legacy. See slab_nomerge for more information. @@ -5100,27 +5324,45 @@ spia_peddr= split_lock_detect= - [X86] Enable split lock detection + [X86] Enable split lock detection or bus lock detection When enabled (and if hardware support is present), atomic instructions that access data across cache line - boundaries will result in an alignment check exception. + boundaries will result in an alignment check exception + for split lock detection or a debug exception for + bus lock detection. off - not enabled - warn - the kernel will emit rate limited warnings + warn - the kernel will emit rate-limited warnings about applications triggering the #AC - exception. This mode is the default on CPUs - that supports split lock detection. + exception or the #DB exception. This mode is + the default on CPUs that support split lock + detection or bus lock detection. Default + behavior is by #AC if both features are + enabled in hardware. fatal - the kernel will send SIGBUS to applications - that trigger the #AC exception. + that trigger the #AC exception or the #DB + exception. Default behavior is by #AC if + both features are enabled in hardware. + + ratelimit:N - + Set system wide rate limit to N bus locks + per second for bus lock detection. + 0 < N <= 1000. + + N/A for split lock detection. + If an #AC exception is hit in the kernel or in firmware (i.e. not while executing in user mode) the kernel will oops in either "warn" or "fatal" mode. + #DB exception for bus lock is triggered only when + CPL > 0. + srbds= [X86,INTEL] Control the Special Register Buffer Data Sampling (SRBDS) mitigation. @@ -5435,12 +5677,25 @@ Note, echoing 1 into this file without the tracepoint_printk kernel cmdline option has no effect. + The tp_printk_stop_on_boot (see below) can also be used + to stop the printing of events to console at + late_initcall_sync. + ** CAUTION ** Having tracepoints sent to printk() and activating high frequency tracepoints such as irq or sched, can cause the system to live lock. + tp_printk_stop_on_boot[FTRACE] + When tp_printk (above) is set, it can cause a lot of noise + on the console. It may be useful to only include the + printing of events during boot up, as user space may + make the system inoperable. + + This command line option will stop the printing of events + to console at the late_initcall_sync() time frame. + traceoff_on_warning [FTRACE] enable this option to disable tracing when a warning is hit. This turns off "tracing_on". Tracing can @@ -5462,6 +5717,18 @@ See Documentation/admin-guide/mm/transhuge.rst for more details. + trusted.source= [KEYS] + Format: <string> + This parameter identifies the trust source as a backend + for trusted keys implementation. Supported trust + sources: + - "tpm" + - "tee" + If not specified then it defaults to iterating through + the trust source list starting with TPM and assigns the + first trust source as a backend which is initialized + successfully during iteration. + tsc= Disable clocksource stability checks for TSC. Format: <string> [x86] reliable: mark tsc clocksource as reliable, this |