diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 195 |
1 files changed, 129 insertions, 66 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 526d65d8573a..bab6a8b01202 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -373,6 +373,12 @@ arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards Format: <io>,<irq>,<nodeID> + arm64.nobti [ARM64] Unconditionally disable Branch Target + Identification support + + arm64.nopauth [ARM64] Unconditionally disable Pointer Authentication + support + ataflop= [HW,M68k] atarimouse= [HW,MOUSE] Atari Mouse @@ -600,7 +606,7 @@ kernel/dma/contiguous.c cma_pernuma=nn[MG] - [ARM64,KNL] + [ARM64,KNL,CMA] Sets the size of kernel per-numa memory area for contiguous memory allocations. A value of 0 disables per-numa CMA altogether. And If this option is not @@ -802,13 +808,14 @@ insecure, please do not use on production kernels. debug_locks_verbose= - [KNL] verbose self-tests - Format=<0|1> + [KNL] verbose locking self-tests + Format: <int> Print debugging info while doing the locking API self-tests. - We default to 0 (no extra messages), setting it to - 1 will print _a lot_ more information - normally - only useful to kernel developers. + Bitmask for the various LOCKTYPE_ tests. Defaults to 0 + (no extra messages), setting it to -1 (all bits set) + will print _a_lot_ more information - normally only + useful to lockdep developers. debug_objects [KNL] Enable object debugging @@ -944,12 +951,6 @@ causing system reset or hang due to sending INIT from AP to BSP. - perf_v4_pmi= [X86,INTEL] - Format: <bool> - Disable Intel PMU counter freezing feature. - The feature only exists starting from - Arch Perfmon v4 (Skylake and newer). - disable_ddw [PPC/PSERIES] Disable Dynamic DMA Window support. Use this to workaround buggy firmware. @@ -1385,7 +1386,7 @@ ftrace_filter=[function-list] [FTRACE] Limit the functions traced by the function - tracer at boot up. function-list is a comma separated + tracer at boot up. function-list is a comma-separated list of functions. This list can be changed at run time by the set_ftrace_filter file in the debugfs tracing directory. @@ -1399,13 +1400,13 @@ ftrace_graph_filter=[function-list] [FTRACE] Limit the top level callers functions traced by the function graph tracer at boot up. - function-list is a comma separated list of functions + function-list is a comma-separated list of functions that can be changed at run time by the set_graph_function file in the debugfs tracing directory. ftrace_graph_notrace=[function-list] [FTRACE] Do not trace from the functions specified in - function-list. This list is a comma separated list of + function-list. This list is a comma-separated list of functions that can be changed at run time by the set_graph_notrace file in the debugfs tracing directory. @@ -1433,6 +1434,11 @@ to enforce probe and suspend/resume ordering. rpm -- Like "on", but also use to order runtime PM. + fw_devlink.strict=<bool> + [KNL] Treat all inferred dependencies as mandatory + dependencies. This only applies for fw_devlink=on|rpm. + Format: <bool> + gamecon.map[2|3]= [HW,JOY] Multisystem joystick and NES/SNES/PSX pad support via parallel port (up to 5 devices per port) @@ -1524,12 +1530,12 @@ hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET registers. Default set by CONFIG_HPET_MMAP_DEFAULT. - hugetlb_cma= [HW] The size of a cma area used for allocation + hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation of gigantic hugepages. Format: nn[KMGTPE] - Reserve a cma area of given size and allocate gigantic - hugepages using the cma allocator. If enabled, the + Reserve a CMA area of given size and allocate gigantic + hugepages using the CMA allocator. If enabled, the boot-time allocation of gigantic hugepages is skipped. hugepages= [HW] Number of HugeTLB pages to allocate at boot. @@ -1673,6 +1679,12 @@ In such case C2/C3 won't be used again. idle=nomwait: Disable mwait for CPU C-states + idxd.sva= [HW] + Format: <bool> + Allow force disabling of Shared Virtual Memory (SVA) + support for the idxd driver. By default it is set to + true (1). + ieee754= [MIPS] Select IEEE Std 754 conformance mode Format: { strict | legacy | 2008 | relaxed } Default: strict @@ -1746,7 +1758,7 @@ ima_policy= [IMA] The builtin policies to load during IMA setup. Format: "tcb | appraise_tcb | secure_boot | - fail_securely" + fail_securely | critical_data" The "tcb" policy measures all programs exec'd, files mmap'd for exec, and all files opened with the read @@ -1765,6 +1777,9 @@ filesystems with the SB_I_UNVERIFIABLE_SIGNATURE flag. + The "critical_data" policy measures kernel integrity + critical data. + ima_tcb [IMA] Deprecated. Use ima_policy= instead. Load a policy which meets the needs of the Trusted Computing Base. This means IMA will measure all @@ -1883,11 +1898,6 @@ Note that using this option lowers the security provided by tboot because it makes the system vulnerable to DMA attacks. - nobounce [Default off] - Disable bounce buffer for untrusted devices such as - the Thunderbolt devices. This will treat the untrusted - devices as the trusted ones, hence might expose security - risks of DMA attacks. intel_idle.max_cstate= [KNL,HW,ACPI,X86] 0 disables intel_idle and fall back on acpi_idle. @@ -2259,6 +2269,19 @@ for all guests. Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. + kvm-arm.mode= + [KVM,ARM] Select one of KVM/arm64's modes of operation. + + nvhe: Standard nVHE-based mode, without support for + protected guests. + + protected: nVHE-based mode with support for guests whose + 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. + kvm-arm.vgic_v3_group0_trap= [KVM,ARM] Trap guest accesses to GICv3 group-0 system registers @@ -2416,7 +2439,7 @@ when set. Format: <int> - libata.force= [LIBATA] Force configurations. The format is comma + libata.force= [LIBATA] Force configurations. The format is comma- separated list of "[ID:]VAL" where ID is PORT[.DEVICE]. PORT and DEVICE are decimal numbers matching port, link or device. Basically, it matches @@ -2709,7 +2732,7 @@ option description. memmap=nn[KMG]@ss[KMG] - [KNL] Force usage of a specific region of memory. + [KNL, X86, MIPS, XTENSA] Force usage of a specific region of memory. Region of memory to be used is from ss to ss+nn. If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG], which limits max address to nn[KMG]. @@ -2858,6 +2881,8 @@ mds=off [X86] tsx_async_abort=off [X86] kvm.nx_huge_pages=off [X86] + no_entry_flush [PPC] + no_uaccess_flush [PPC] Exceptions: This does not have any effect on @@ -2951,7 +2976,7 @@ mtdset= [ARM] ARM/S3C2412 JIVE boot control - See arch/arm/mach-s3c2412/mach-jive.c + See arch/arm/mach-s3c/mach-jive.c mtouchusb.raw_coordinates= [HW] Make the MicroTouch USB driver use raw coordinates @@ -3186,6 +3211,8 @@ noefi Disable EFI runtime services support. + no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel. + noexec [IA-64] noexec [X86] @@ -3235,6 +3262,9 @@ nospec_store_bypass_disable [HW] Disable all mitigations for the Speculative Store Bypass vulnerability + no_uaccess_flush + [PPC] Don't flush the L1-D cache after accessing user data. + noxsave [BUGS=X86] Disables x86 extended register state save and restore using xsave. The kernel will fallback to enabling legacy floating-point and sse state. @@ -3254,9 +3284,14 @@ parameter, xsave area per process might occupy more memory on xsaves enabled systems. - nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or - wfi(ARM) instruction doesn't work correctly and not to - use it. This is also useful when using JTAG debugger. + nohlt [ARM,ARM64,MICROBLAZE,SH] Forces the kernel to busy wait + in do_idle() and not use the arch_cpu_idle() + implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP + to be effective. This is useful on platforms where the + sleep(SH) or wfi(ARM,ARM64) instructions do not work + correctly or when doing power measurements to evalute + the impact of the sleep instructions. This is also + useful when using JTAG debugger. no_file_caps Tells the kernel not to honor file capabilities. The only way then for a file to be executed with privilege @@ -3269,6 +3304,21 @@ in certain environments such as networked servers or real-time systems. + no_hash_pointers + Force pointers printed to the console or buffers to be + unhashed. By default, when a pointer is printed via %p + format string, that pointer is "hashed", i.e. obscured + by hashing the pointer value. This is a security feature + that hides actual kernel addresses from unprivileged + users, but it also makes debugging the kernel more + difficult since unequal pointers can no longer be + compared. However, if this command-line option is + specified, then all normal pointers will have their true + value printed. Pointers printed via %pK may still be + hashed. This option should only be specified when + debugging the kernel. Please do not use on production + kernels. + nohibernate [HIBERNATION] Disable hibernation and resume. nohz= [KNL] Boottime enable/disable dynamic ticks @@ -3368,6 +3418,8 @@ nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. + nosgx [X86-64,SGX] Disables Intel SGX kernel support. + nosmp [SMP] Tells an SMP kernel to act as a UP kernel, and disable the IO APIC. legacy for "maxcpus=0". @@ -3444,20 +3496,6 @@ For example, to override I2C bus2: omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 - oprofile.timer= [HW] - Use timer interrupt instead of performance counters - - oprofile.cpu_type= Force an oprofile cpu type - This might be useful if you have an older oprofile - userland or if you want common events. - Format: { arch_perfmon } - arch_perfmon: [X86] Force use of architectural - perfmon on Intel CPUs instead of the - CPU specific event set. - timer: [X86] Force use of architectural NMI - timer mode (see also oprofile.timer - for generic hr timer mode) - oops=panic Always panic on oopses. Default is to just kill the process, but there is a small probability of deadlocking the machine. @@ -3902,6 +3940,13 @@ Format: {"off"} Disable Hardware Transactional Memory + preempt= [KNL] + Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC + none - Limited to cond_resched() calls + voluntary - Limited to cond_resched() and might_sleep() calls + full - Any section that isn't explicitly preempt disabled + can be preempted anytime. + print-fatal-signals= [KNL] debug: print fatal signals @@ -4078,6 +4123,10 @@ value, meaning that RCU_SOFTIRQ is used by default. Specify rcutree.use_softirq=0 to use rcuc kthreads. + But note that CONFIG_PREEMPT_RT=y kernels disable + this kernel boot parameter, forcibly setting it + to zero. + rcutree.rcu_fanout_exact= [KNL] Disable autobalancing of the rcu_node combining tree. This is used by rcutorture, and might @@ -4165,12 +4214,6 @@ Set wakeup interval for idle CPUs that have RCU callbacks (RCU_FAST_NO_HZ=y). - rcutree.rcu_idle_lazy_gp_delay= [KNL] - Set wakeup interval for idle CPUs that have - only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). - Lazy RCU callbacks are those which RCU can - prove do nothing more than free memory. - rcutree.rcu_kick_kthreads= [KNL] Cause the grace-period kthread to get an extra wake_up() if it sleeps three times longer than @@ -4324,6 +4367,14 @@ stress RCU, they don't participate in the actual test, hence the "fake". + rcutorture.nocbs_nthreads= [KNL] + Set number of RCU callback-offload togglers. + Zero (the default) disables toggling. + + rcutorture.nocbs_toggle= [KNL] + Set the delay in milliseconds between successive + callback-offload toggling attempts. + rcutorture.nreaders= [KNL] Set number of RCU readers. The value -1 selects N-1, where N is the number of CPUs. A value @@ -4456,6 +4507,13 @@ only normal grace-period primitives. No effect on CONFIG_TINY_RCU kernels. + But note that CONFIG_PREEMPT_RT=y kernels enables + this kernel boot parameter, forcibly setting + it to the value one, that is, converting any + post-boot attempt at an expedited RCU grace + period to instead use normal non-expedited + grace-period processing. + rcupdate.rcu_task_ipi_delay= [KNL] Set time in jiffies during which RCU tasks will avoid sending IPIs, starting with the beginning @@ -4543,6 +4601,12 @@ refscale.verbose= [KNL] Enable additional printk() statements. + refscale.verbose_batched= [KNL] + Batch the additional printk() statements. If zero + (the default) or negative, print everything. Otherwise, + print every Nth verbose statement, where N is the value + specified. + relax_domain_level= [KNL, SMP] Set scheduler's default relax_domain_level. See Documentation/admin-guide/cgroup-v1/cpusets.rst. @@ -4840,14 +4904,6 @@ last alloc / free. For more information see Documentation/vm/slub.rst. - slub_memcg_sysfs= [MM, SLUB] - Determines whether to enable sysfs directories for - memory cgroup sub-caches. 1 to enable, 0 to disable. - The default is determined by CONFIG_SLUB_MEMCG_SYSFS_ON. - Enabling this can lead to a very high number of debug - directories and files being created under - /sys/kernel/slub. - slub_max_order= [MM, SLUB] Determines the maximum allowed order for slabs. A high setting may cause OOMs due to memory @@ -5131,7 +5187,7 @@ stacktrace_filter=[function-list] [FTRACE] Limit the functions that the stack tracer - will trace at boot up. function-list is a comma separated + will trace at boot up. function-list is a comma-separated list of functions. This list can be changed at run time by the stack_trace_filter file in the debugfs tracing directory. Note, this enables stack tracing @@ -5317,6 +5373,14 @@ are running concurrently, especially on systems with rotating-rust storage. + torture.verbose_sleep_frequency= [KNL] + Specifies how many verbose printk()s should be + emitted between each sleep. The default of zero + disables verbose-printk() sleeping. + + torture.verbose_sleep_duration= [KNL] + Duration of each verbose-printk() sleep in jiffies. + tp720= [HW,PS2] tpm_suspend_pcr=[HW,TPM] @@ -5334,7 +5398,7 @@ trace_event=[event-list] [FTRACE] Set and start specified trace events in order to facilitate early boot debugging. The event-list is a - comma separated list of trace events to enable. See + comma-separated list of trace events to enable. See also Documentation/trace/events.rst trace_options=[option-list] @@ -5656,6 +5720,7 @@ device); j = NO_REPORT_LUNS (don't use report luns command, uas only); + k = NO_SAME (do not use WRITE_SAME, uas only) l = NOT_LOCKABLE (don't try to lock and unlock ejectable media, not on uas); m = MAX_SECTORS_64 (don't transfer more @@ -5917,12 +5982,6 @@ default x2apic cluster mode on platforms supporting x2apic. - x86_intel_mid_timer= [X86-32,APBT] - Choose timer option for x86 Intel MID platform. - Two valid options are apbt timer only and lapic timer - plus one apbt timer for broadcast timer. - x86_intel_mid_timer=apbt_only | lapic_and_apbt - xen_512gb_limit [KNL,X86-64,XEN] Restricts the kernel running paravirtualized under Xen to use only up to 512 GB of RAM. The reason to do so is @@ -5957,6 +6016,10 @@ This option is obsoleted by the "nopv" option, which has equivalent effect for XEN platform. + xen_no_vector_callback + [KNL,X86,XEN] Disable the vector callback for Xen + event channel interrupts. + xen_scrub_pages= [XEN] Boolean option to control scrubbing pages before giving them back to Xen, for use by other domains. Can be also changed at runtime |