diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 110 |
1 files changed, 87 insertions, 23 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb8752b42ec8..d9fd26b95b34 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -416,10 +416,6 @@ Format: { quiet (default) | verbose | debug } Change the amount of debugging information output when initialising the APIC and IO-APIC components. - For X86-32, this can also be used to specify an APIC - driver name. - Format: apic=driver_name - Examples: apic=bigsmp apic_extnmi= [APIC,X86,EARLY] External NMI delivery setting Format: { bsp (default) | all | none } @@ -1411,7 +1407,8 @@ earlyprintk=serial[,0x...[,baudrate]] earlyprintk=ttySn[,baudrate] earlyprintk=dbgp[debugController#] - earlyprintk=pciserial[,force],bus:device.function[,baudrate] + earlyprintk=mmio32,membase[,{nocfg|baudrate}] + earlyprintk=pciserial[,force],bus:device.function[,{nocfg|baudrate}] earlyprintk=xdbc[xhciController#] earlyprintk=bios @@ -1419,6 +1416,9 @@ the normal console is initialized. It is not enabled by default because it has some cosmetic problems. + Use "nocfg" to skip UART configuration, assume + BIOS/firmware has configured UART correctly. + Append ",keep" to not disable it when the real console takes over. @@ -1785,7 +1785,9 @@ allocation boundaries as a proactive defense against bounds-checking flaws in the kernel's copy_to_user()/copy_from_user() interface. - on Perform hardened usercopy checks (default). + The default is determined by + CONFIG_HARDENED_USERCOPY_DEFAULT_ON. + on Perform hardened usercopy checks. off Disable hardened usercopy checks. hardlockup_all_cpu_backtrace= @@ -1861,7 +1863,7 @@ hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET registers. Default set by CONFIG_HPET_MMAP_DEFAULT. - hugepages= [HW] Number of HugeTLB pages to allocate at boot. + hugepages= [HW,EARLY] Number of HugeTLB pages to allocate at boot. If this follows hugepagesz (below), it specifies the number of pages of hugepagesz to be allocated. If this is the first HugeTLB parameter on the command @@ -1873,15 +1875,24 @@ <node>:<integer>[,<node>:<integer>] hugepagesz= - [HW] The size of the HugeTLB pages. This is used in - conjunction with hugepages (above) to allocate huge - pages of a specific size at boot. The pair - hugepagesz=X hugepages=Y can be specified once for - each supported huge page size. Huge page sizes are - architecture dependent. See also + [HW,EARLY] The size of the HugeTLB pages. This is + used in conjunction with hugepages (above) to + allocate huge pages of a specific size at boot. The + pair hugepagesz=X hugepages=Y can be specified once + for each supported huge page size. Huge page sizes + are architecture dependent. See also Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugepage_alloc_threads= + [HW] The number of threads that should be used to + allocate hugepages during boot. This option can be + used to improve system bootup time when allocating + a large amount of huge pages. + The default value is 25% of the available hardware threads. + + Note that this parameter only applies to non-gigantic huge pages. + hugetlb_cma= [HW,CMA,EARLY] The size of a CMA area used for allocation of gigantic hugepages. Or using node format, the size of a CMA area per node can be specified. @@ -1892,6 +1903,13 @@ hugepages using the CMA allocator. If enabled, the boot-time allocation of gigantic hugepages is skipped. + hugetlb_cma_only= + [HW,CMA,EARLY] When allocating new HugeTLB pages, only + try to allocate from the CMA areas. + + This option does nothing if hugetlb_cma= is not also + specified. + hugetlb_free_vmemmap= [KNL] Requires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP enabled. @@ -1933,6 +1951,12 @@ which allow the hypervisor to 'idle' the guest on lock contention. + hw_protection= [HW] + Format: reboot | shutdown + + Hardware protection action taken on critical events like + overtemperature or imminent voltage loss. + i2c_bus= [HW] Override the default board specific I2C bus speed or register an additional I2C bus that is not registered from board initialization code. @@ -2316,6 +2340,9 @@ per_cpu_perf_limits Allow per-logical-CPU P-State performance control limits using cpufreq sysfs interface + no_cas + Do not enable capacity-aware scheduling (CAS) on + hybrid systems intremap= [X86-64,Intel-IOMMU,EARLY] on enable Interrupt Remapping (default) @@ -3116,6 +3143,8 @@ * max_sec_lba48: Set or clear transfer size limit to 65535 sectors. + * external: Mark port as external (hotplug-capable). + * [no]lpm: Enable or disable link power management. * [no]setxfer: Indicate if transfer speed mode setting @@ -4233,10 +4262,10 @@ nosmp [SMP,EARLY] Tells an SMP kernel to act as a UP kernel, and disable the IO APIC. legacy for "maxcpus=0". - nosmt [KNL,MIPS,PPC,S390,EARLY] Disable symmetric multithreading (SMT). + nosmt [KNL,MIPS,PPC,EARLY] Disable symmetric multithreading (SMT). Equivalent to smt=1. - [KNL,X86,PPC] Disable symmetric multithreading (SMT). + [KNL,X86,PPC,S390] Disable symmetric multithreading (SMT). nosmt=force: Force disable SMT, cannot be undone via the sysfs control file. @@ -5017,6 +5046,14 @@ Format: <bool> default: 0 (auto_verbose is enabled) + printk.debug_non_panic_cpus= + Allows storing messages from non-panic CPUs into + the printk log buffer during panic(). They are + flushed to consoles by the panic-CPU on + a best-effort basis. + Format: <bool> (1/Y/y=enable, 0/N/n=disable) + Default: disabled + printk.devkmsg={on,off,ratelimit} Control writing to /dev/kmsg. on - unlimited logging to /dev/kmsg from userspace @@ -5758,6 +5795,11 @@ rcutorture.test_boost_duration= [KNL] Duration (s) of each individual boost test. + rcutorture.test_boost_holdoff= [KNL] + Holdoff time (s) from start of test to the start + of RCU priority-boost testing. Defaults to zero, + that is, no holdoff. + rcutorture.test_boost_interval= [KNL] Interval (s) between each boost test. @@ -6082,7 +6124,7 @@ is assumed to be I/O ports; otherwise it is memory. reserve_mem= [RAM] - Format: nn[KNG]:<align>:<label> + Format: nn[KMG]:<align>:<label> Reserve physical memory and label it with a name that other subsystems can use to access it. This is typically used for systems that do not wipe the RAM, and this command @@ -6582,6 +6624,8 @@ Selecting 'on' will also enable the mitigation against user space to user space task attacks. + Selecting specific mitigation does not force enable + user mitigations. Selecting 'off' will disable both the kernel and the user space protections. @@ -7241,6 +7285,8 @@ This is just one of many ways that can clear memory. Make sure your system keeps the content of memory across reboots before relying on this option. + NB: Both the mapped address and size must be page aligned for the architecture. + See also Documentation/trace/debugging.rst @@ -7279,6 +7325,15 @@ See also "Event triggers" in Documentation/trace/events.rst + traceoff_after_boot + [FTRACE] Sometimes tracing is used to debug issues + during the boot process. Since the trace buffer has a + limited amount of storage, it may be prudent to + disable tracing after the boot is finished, otherwise + the critical information may be overwritten. With this + option, the main tracing buffer will be turned off at + the end of the boot process. + traceoff_on_warning [FTRACE] enable this option to disable tracing when a warning is hit. This turns off "tracing_on". Tracing can @@ -7477,6 +7532,22 @@ Note that genuine overcurrent events won't be reported either. + unaligned_scalar_speed= + [RISCV] + Format: {slow | fast | unsupported} + Allow skipping scalar unaligned access speed tests. This + is useful for testing alternative code paths and to skip + the tests in environments where they run too slowly. All + CPUs must have the same scalar unaligned access speed. + + unaligned_vector_speed= + [RISCV] + Format: {slow | fast | unsupported} + Allow skipping vector unaligned access speed tests. This + is useful for testing alternative code paths and to skip + the tests in environments where they run too slowly. All + CPUs must have the same vector unaligned access speed. + unknown_nmi_panic [X86] Cause panic on unknown NMI. @@ -7672,13 +7743,6 @@ 16 - SIGBUS faults Example: user_debug=31 - userpte= - [X86,EARLY] Flags controlling user PTE allocations. - - nohigh = do not allocate PTE pages in - HIGHMEM regardless of setting - of CONFIG_HIGHPTE. - vdso= [X86,SH,SPARC] On X86_32, this is an alias for vdso32=. Otherwise: |