diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 145 |
1 files changed, 100 insertions, 45 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ef9f80b1ddde..426fa892d311 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1158,8 +1158,12 @@ nopku [X86] Disable Memory Protection Keys CPU feature found in some Intel CPUs. - <module>.async_probe [KNL] - Enable asynchronous probe on this module. + <module>.async_probe[=<bool>] [KNL] + If no <bool> value is specified or if the value + specified is not a valid <bool>, enable asynchronous + probe on this module. Otherwise, enable/disable + asynchronous probe on this module as indicated by the + <bool> value. See also: module.async_probe early_ioremap_debug [KNL] Enable debug messages in early_ioremap support. This @@ -1673,6 +1677,19 @@ hlt [BUGS=ARM,SH] + hostname= [KNL] Set the hostname (aka UTS nodename). + Format: <string> + This allows setting the system's hostname during early + startup. This sets the name returned by gethostname. + Using this parameter to set the hostname makes it + possible to ensure the hostname is correctly set before + any userspace processes run, avoiding the possibility + that a process may call gethostname before the hostname + has been explicitly set, resulting in the calling + process getting an incorrect result. The string must + not exceed the maximum allowed hostname length (usually + 64 characters) and will be truncated otherwise. + hpet= [X86-32,HPET] option to control HPET usage Format: { enable (default) | disable | force | verbose } @@ -1718,19 +1735,22 @@ hugetlb_free_vmemmap= [KNL] Reguires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP enabled. + Control if HugeTLB Vmemmap Optimization (HVO) is enabled. Allows heavy hugetlb users to free up some more memory (7 * PAGE_SIZE for each 2MB hugetlb page). - Format: { [oO][Nn]/Y/y/1 | [oO][Ff]/N/n/0 (default) } + Format: { on | off (default) } - [oO][Nn]/Y/y/1: enable the feature - [oO][Ff]/N/n/0: disable the feature + on: enable HVO + off: disable HVO Built with CONFIG_HUGETLB_PAGE_OPTIMIZE_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. + Note that the vmemmap pages may be allocated from the added + memory block itself when memory_hotplug.memmap_on_memory is + enabled, those vmemmap pages cannot be optimized even if this + feature is enabled. Other vmemmap pages not allocated from + the added memory block itself do not be affected. hung_task_panic= [KNL] Should the hung task detector generate panics. @@ -2272,23 +2292,39 @@ 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: + mapping provided in the IVRS ACPI table. + By default, PCI segment is 0, and can be omitted. + For example: + * To map IOAPIC-ID decimal 10 to PCI device 00:14.0 + write the parameter as: ivrs_ioapic[10]=00:14.0 + * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and + PCI device 00:14.0 write the parameter as: + ivrs_ioapic[10]=0001:00:14.0 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: + mapping provided in the IVRS ACPI table. + By default, PCI segment is 0, and can be omitted. + For example: + * To map HPET-ID decimal 0 to PCI device 00:14.0 + write the parameter as: ivrs_hpet[0]=00:14.0 + * To map HPET-ID decimal 10 to PCI segment 0x1 and + PCI device 00:14.0 write the parameter as: + ivrs_ioapic[10]=0001:00:14.0 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 - PCI device 00:14.5 write the parameter as: + mapping provided in the IVRS ACPI table. + + For example, to map UART-HID:UID AMD0020:0 to + PCI segment 0x1 and PCI device ID 00:14.5, + write the parameter as: + ivrs_acpihid[0001:00:14.5]=AMD0020:0 + + By default, PCI segment is 0, and can be omitted. + For example, PCI device 00:14.5 write the parameter as: ivrs_acpihid[00:14.5]=AMD0020:0 js= [HW,JOY] Analog joystick @@ -3073,10 +3109,12 @@ [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. + allocate its internal metadata (struct pages, + those vmemmap pages cannot be optimized even + if hugetlb_free_vmemmap is enabled) 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 @@ -3086,10 +3124,6 @@ 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,M68K,PPC,RISCV] Enable memtest Format: <integer> default : 0 <disable> @@ -3248,6 +3282,15 @@ For details see: Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst + module.async_probe=<bool> + [KNL] When set to true, modules will use async probing + by default. To enable/disable async probing for a + specific module, use the module specific control that + is documented under <module>.async_probe. When both + module.async_probe and <module>.async_probe are + specified, <module>.async_probe takes precedence for + the specific module. + module.sig_enforce [KNL] When CONFIG_MODULE_SIG is set, this means that modules without (valid) signatures will fail to load. @@ -3537,9 +3580,6 @@ noautogroup Disable scheduler automatic task group creation. - nobats [PPC] Do not use BATs for mapping kernel lowmem - on "Classic" PPC cores. - nocache [ARM] nodsp [SH] Disable hardware DSP at boot time. @@ -3709,9 +3749,6 @@ nolapic_timer [X86-32,APIC] Do not use the local APIC timer. - noltlbs [PPC] Do not use large page/tlb entries for kernel - lowmem mapping on PPC40x and PPC8xx - nomca [IA-64] Disable machine check abort handling nomce [X86-32] Disable Machine Check Exception @@ -5237,20 +5274,33 @@ Speculative Code Execution with Return Instructions) vulnerability. + AMD-based UNRET and IBPB mitigations alone do not stop + sibling threads from influencing the predictions of other + sibling threads. For that reason, STIBP is used on pro- + cessors that support it, and mitigate SMT on processors + that don't. + off - no mitigation auto - automatically select a migitation auto,nosmt - automatically select a mitigation, disabling SMT if necessary for the full mitigation (only on Zen1 and older without STIBP). - ibpb - mitigate short speculation windows on - basic block boundaries too. Safe, highest - perf impact. - unret - force enable untrained return thunks, - only effective on AMD f15h-f17h - based systems. - unret,nosmt - like unret, will disable SMT when STIBP - is not available. + ibpb - On AMD, mitigate short speculation + windows on basic block boundaries too. + Safe, highest perf impact. It also + enables STIBP if present. Not suitable + on Intel. + ibpb,nosmt - Like "ibpb" above but will disable SMT + when STIBP is not available. This is + the alternative for systems which do not + have STIBP. + unret - Force enable untrained return thunks, + only effective on AMD f15h-f17h based + systems. + unret,nosmt - Like unret, but will disable SMT when STIBP + is not available. This is the alternative for + systems which do not have STIBP. Selecting 'auto' will choose a mitigation method at run time according to the CPU. @@ -5281,6 +5331,8 @@ rodata= [KNL] on Mark read-only kernel memory as read-only (default). off Leave read-only kernel memory writable for debugging. + full Mark read-only kernel memory and aliases as read-only + [arm64] rockchip.usb_uart Enable the uart passthrough on the designated usb port @@ -5502,7 +5554,7 @@ cache (risks via metadata attacks are mostly unchanged). Debug options disable merging on their own. - For more information see Documentation/vm/slub.rst. + For more information see Documentation/mm/slub.rst. slab_max_order= [MM, SLAB] Determines the maximum allowed order for slabs. @@ -5516,13 +5568,13 @@ slub_debug can create guard zones around objects and may poison objects when not in use. Also tracks the last alloc / free. For more information see - Documentation/vm/slub.rst. + Documentation/mm/slub.rst. slub_max_order= [MM, SLUB] Determines the maximum allowed order for slabs. A high setting may cause OOMs due to memory fragmentation. For more information see - Documentation/vm/slub.rst. + Documentation/mm/slub.rst. slub_min_objects= [MM, SLUB] The minimum number of objects per slab. SLUB will @@ -5531,12 +5583,12 @@ the number of objects indicated. The higher the number of objects the smaller the overhead of tracking slabs and the less frequently locks need to be acquired. - For more information see Documentation/vm/slub.rst. + For more information see Documentation/mm/slub.rst. slub_min_order= [MM, SLUB] Determines the minimum page order for slabs. Must be lower than slub_max_order. - For more information see Documentation/vm/slub.rst. + For more information see Documentation/mm/slub.rst. slub_merge [MM, SLUB] Same with slab_merge. @@ -5983,8 +6035,11 @@ it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst) swiotlb= [ARM,IA-64,PPC,MIPS,X86] - Format: { <int> | force | noforce } + Format: { <int> [,<int>] | force | noforce } <int> -- Number of I/O TLB slabs + <int> -- Second integer after comma. Number of swiotlb + areas with their own lock. Will be rounded up + to a power of 2. force -- force using of bounce buffers even if they wouldn't be automatically used by the kernel noforce -- Never use bounce buffers (for debugging) |