diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 219 |
1 files changed, 123 insertions, 96 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5e4ee29cf393..6221a1d057dd 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -378,18 +378,16 @@ autoconf= [IPV6] See Documentation/networking/ipv6.rst. - show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller - Limit apic dumping. The parameter defines the maximal - number of local apics being dumped. Also it is possible - to set it to "all" by meaning -- no limit here. - Format: { 1 (default) | 2 | ... | all }. - The parameter valid if only apic=debug or - apic=verbose is specified. - Example: apic=debug show_lapic=all - apm= [APM] Advanced Power Management See header of arch/x86/kernel/apm_32.c. + apparmor= [APPARMOR] Disable or enable AppArmor at boot time + Format: { "0" | "1" } + See security/apparmor/Kconfig help text + 0 -- disable. + 1 -- enable. + Default value is set via kernel config option. + arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards Format: <io>,<irq>,<nodeID> @@ -480,8 +478,10 @@ See Documentation/block/cmdline-partition.rst boot_delay= Milliseconds to delay each printk during boot. - Values larger than 10 seconds (10000) are changed to - no delay (0). + Only works if CONFIG_BOOT_PRINTK_DELAY is enabled, + and you may also have to specify "lpj=". Boot_delay + values larger than 10 seconds (10000) are assumed + erroneous and ignored. Format: integer bootconfig [KNL] @@ -673,7 +673,7 @@ 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 - specificed, the default value is 0. + specified, the default value is 0. With per-numa CMA enabled, DMA users on node nid will first try to allocate buffer from the pernuma area which is located in node nid, if the allocation fails, @@ -945,7 +945,7 @@ driver code when a CPU writes to (or reads from) a random memory location. Note that there exists a class of memory corruptions problems caused by buggy H/W or - F/W or by drivers badly programing DMA (basically when + F/W or by drivers badly programming DMA (basically when memory is written at bus level and the CPU MMU is bypassed) which are not detectable by CONFIG_DEBUG_PAGEALLOC, hence this option will not help @@ -1046,26 +1046,12 @@ can be useful when debugging issues that require an SLB miss to occur. - stress_slb [PPC] - Limits the number of kernel SLB entries, and flushes - them frequently to increase the rate of SLB faults - on kernel addresses. - - stress_hpt [PPC] - Limits the number of kernel HPT entries in the hash - page table to increase the rate of hash page table - faults on kernel addresses. - disable= [IPV6] See Documentation/networking/ipv6.rst. 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. @@ -1167,16 +1153,6 @@ Documentation/admin-guide/dynamic-debug-howto.rst for details. - nopku [X86] Disable Memory Protection Keys CPU feature found - in some Intel CPUs. - - <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 is useful for tracking down temporary early mappings @@ -1196,10 +1172,10 @@ specified, the serial port must already be setup and configured. - uart[8250],io,<addr>[,options] - uart[8250],mmio,<addr>[,options] - uart[8250],mmio32,<addr>[,options] - uart[8250],mmio32be,<addr>[,options] + uart[8250],io,<addr>[,options[,uartclk]] + uart[8250],mmio,<addr>[,options[,uartclk]] + uart[8250],mmio32,<addr>[,options[,uartclk]] + uart[8250],mmio32be,<addr>[,options[,uartclk]] uart[8250],0x<addr>[,options] Start an early, polled-mode console on the 8250/16550 UART at the specified I/O port or MMIO address. @@ -1208,7 +1184,9 @@ If none of [io|mmio|mmio32|mmio32be], <addr> is assumed to be equivalent to 'mmio'. 'options' are specified in the same format described for "console=ttyS<n>"; if - unspecified, the h/w is not initialized. + unspecified, the h/w is not initialized. 'uartclk' is + the uart clock frequency; if unspecified, it is set + to 'BASE_BAUD' * 16. pl011,<addr> pl011,mmio32,<addr> @@ -1533,6 +1511,15 @@ boot up that is likely to be overridden by user space start up functionality. + Optionally, the snapshot can also be defined for a tracing + instance that was created by the trace_instance= command + line parameter. + + trace_instance=foo,sched_switch ftrace_boot_snapshot=foo + + The above will cause the "foo" tracing instance to trigger + a snapshot at the end of boot up. + ftrace_dump_on_oops[=orig_cpu] [FTRACE] will dump the trace buffers on oops. If no parameter is passed, ftrace will dump @@ -1753,7 +1740,7 @@ boot-time allocation of gigantic hugepages is skipped. hugetlb_free_vmemmap= - [KNL] Reguires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP + [KNL] Requires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP enabled. Control if HugeTLB Vmemmap Optimization (HVO) is enabled. Allows heavy hugetlb users to free up some more @@ -1792,12 +1779,6 @@ which allow the hypervisor to 'idle' the guest on lock contention. - keep_bootcon [KNL] - Do not unregister boot console at start. This is only - useful for debugging when something happens in the window - between unregistering the boot console and initializing - the real console. - 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. @@ -2367,17 +2348,18 @@ js= [HW,JOY] Analog joystick See Documentation/input/joydev/joystick.rst. - nokaslr [KNL] - When CONFIG_RANDOMIZE_BASE is set, this disables - kernel and module base offset ASLR (Address Space - Layout Randomization). - kasan_multi_shot [KNL] Enforce KASAN (Kernel Address Sanitizer) to print report on every invalid memory access. Without this parameter KASAN will print report only for the first invalid access. + keep_bootcon [KNL] + Do not unregister boot console at start. This is only + useful for debugging when something happens in the window + between unregistering the boot console and initializing + the real console. + keepinitrd [HW,ARM] kernelcore= [KNL,X86,IA-64,PPC] @@ -2554,9 +2536,14 @@ protected: nVHE-based mode with support for guests whose state is kept private from the host. + nested: VHE-based mode with support for nested + virtualization. Requires at least ARMv8.3 + hardware. + Defaults to VHE/nVHE based on hardware support. Setting mode to "protected" will disable kexec and hibernation - for the host. + for the host. "nested" is experimental and should be + used with extreme caution. kvm-arm.vgic_v3_group0_trap= [KVM,ARM] Trap guest accesses to GICv3 group-0 @@ -2817,6 +2804,9 @@ * [no]setxfer: Indicate if transfer speed mode setting should be skipped. + * [no]fua: Disable or enable FUA (Force Unit Access) + support for devices supporting this feature. + * dump_id: Dump IDENTIFY data. * disable: Disable this device. @@ -3326,6 +3316,13 @@ For details see: Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst + <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 + module.async_probe=<bool> [KNL] When set to true, modules will use async probing by default. To enable/disable async probing for a @@ -3709,7 +3706,7 @@ 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 + correctly or when doing power measurements to evaluate the impact of the sleep instructions. This is also useful when using JTAG debugger. @@ -3780,6 +3777,11 @@ nojitter [IA-64] Disables jitter checking for ITC timers. + nokaslr [KNL] + When CONFIG_RANDOMIZE_BASE is set, this disables + kernel and module base offset ASLR (Address Space + Layout Randomization). + no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page @@ -3825,6 +3827,19 @@ nopcid [X86-64] Disable the PCID cpu feature. + nopku [X86] Disable Memory Protection Keys CPU feature found + in some Intel CPUs. + + nopv= [X86,XEN,KVM,HYPER_V,VMWARE] + Disables the PV optimizations forcing the guest to run + 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. + norandmaps Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space @@ -4118,10 +4133,6 @@ pcbit= [HW,ISDN] - pcd. [PARIDE] - See header of drivers/block/paride/pcd.c. - See also Documentation/admin-guide/blockdev/paride.rst. - pci=option[,option...] [PCI] various PCI subsystem options. Some options herein operate on a specific device @@ -4297,7 +4308,9 @@ specified, e.g., 12@pci:8086:9c22:103c:198f for 4096-byte alignment. ecrc= Enable/disable PCIe ECRC (transaction layer - end-to-end CRC checking). + end-to-end CRC checking). Only effective if + OS has native AER control (either granted by + ACPI _OSC or forced via "pcie_ports=native") bios: Use BIOS/firmware settings. This is the the default. off: Turn ECRC off @@ -4384,9 +4397,6 @@ for debug and development, but should not be needed on a platform with proper driver support. - pd. [PARIDE] - See Documentation/admin-guide/blockdev/paride.rst. - pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at boot time. Format: { 0 | 1 } @@ -4399,12 +4409,6 @@ allocator. This parameter is primarily for debugging and performance comparison. - pf. [PARIDE] - See Documentation/admin-guide/blockdev/paride.rst. - - pg. [PARIDE] - See Documentation/admin-guide/blockdev/paride.rst. - pirq= [SMP,APIC] Manual mp-table setup See Documentation/x86/i386/IO-APIC.rst. @@ -4566,9 +4570,6 @@ pstore.backend= Specify the name of the pstore backend to use - pt. [PARIDE] - See Documentation/admin-guide/blockdev/paride.rst. - pti= [X86-64] Control Page Table Isolation of user and kernel address spaces. Disabling this feature removes hardening, but improves performance of @@ -4592,6 +4593,10 @@ r128= [HW,DRM] + radix_hcall_invalidate=on [PPC/PSERIES] + Disable RADIX GTSE feature and use hcall for TLB + invalidate. + raid= [HW,RAID] See Documentation/admin-guide/md.rst. @@ -5584,13 +5589,6 @@ 1 -- enable. Default value is 1. - apparmor= [APPARMOR] Disable or enable AppArmor at boot time - Format: { "0" | "1" } - See security/apparmor/Kconfig help text - 0 -- disable. - 1 -- enable. - Default value is set via kernel config option. - serialnumber [BUGS=X86-32] sev=option[,option...] [X86-64] See Documentation/x86/x86_64/boot-options.rst @@ -5598,6 +5596,15 @@ shapers= [NET] Maximal number of shapers. + show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller + Limit apic dumping. The parameter defines the maximal + number of local apics being dumped. Also it is possible + to set it to "all" by meaning -- no limit here. + Format: { 1 (default) | 2 | ... | all }. + The parameter valid if only apic=debug or + apic=verbose is specified. + Example: apic=debug show_lapic=all + simeth= [IA-64] simscsi= @@ -6037,6 +6044,16 @@ be used to filter out binaries which have not yet been made aware of AT_MINSIGSTKSZ. + stress_hpt [PPC] + Limits the number of kernel HPT entries in the hash + page table to increase the rate of hash page table + faults on kernel addresses. + + stress_slb [PPC] + Limits the number of kernel SLB entries, and flushes + them frequently to increase the rate of SLB faults + on kernel addresses. + sunrpc.min_resvport= sunrpc.max_resvport= [NFS,SUNRPC] @@ -6284,13 +6301,33 @@ comma-separated list of trace events to enable. See also Documentation/trace/events.rst + trace_instance=[instance-info] + [FTRACE] Create a ring buffer instance early in boot up. + This will be listed in: + + /sys/kernel/tracing/instances + + Events can be enabled at the time the instance is created + via: + + trace_instance=<name>,<system1>:<event1>,<system2>:<event2> + + Note, the "<system*>:" portion is optional if the event is + unique. + + trace_instance=foo,sched:sched_switch,irq_handler_entry,initcall + + will enable the "sched_switch" event (note, the "sched:" is optional, and + the same thing would happen if it was left off). The irq_handler_entry + event, and all events under the "initcall" system. + trace_options=[option-list] [FTRACE] Enable or disable tracer options at boot. The option-list is a comma delimited list of options that can be enabled or disabled just as if you were to echo the option name into - /sys/kernel/debug/tracing/trace_options + /sys/kernel/tracing/trace_options For example, to enable stacktrace option (to dump the stack trace of each event), add to the command line: @@ -6323,7 +6360,7 @@ [FTRACE] enable this option to disable tracing when a warning is hit. This turns off "tracing_on". Tracing can be enabled again by echoing '1' into the "tracing_on" - file located in /sys/kernel/debug/tracing/ + file located in /sys/kernel/tracing/ This option is useful, as it disables the trace before the WARNING dump is called, which prevents the trace to @@ -6778,11 +6815,11 @@ functions are at fixed addresses, they make nice targets for exploits that can control RIP. - emulate [default] Vsyscalls turn into traps and are - emulated reasonably safely. The vsyscall - page is readable. + emulate Vsyscalls turn into traps and are emulated + reasonably safely. The vsyscall page is + readable. - xonly Vsyscalls turn into traps and are + xonly [default] Vsyscalls turn into traps and are emulated reasonably safely. The vsyscall page is not readable. @@ -6979,16 +7016,6 @@ fairer and the number of possible event channels is much higher. Default is on (use fifo events). - nopv= [X86,XEN,KVM,HYPER_V,VMWARE] - Disables the PV optimizations forcing the guest to run - 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>]]] |