diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 215 |
1 files changed, 161 insertions, 54 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 05496622b4ef..1d1d53f85ddd 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -114,7 +114,6 @@ This facility can be used to prevent such uncontrolled GPE floodings. Format: <int> - Support masking of GPEs numbered from 0x00 to 0x7f. acpi_no_auto_serialize [HW,ACPI] Disable auto-serialization of AML methods @@ -223,7 +222,7 @@ acpi_sleep= [HW,ACPI] Sleep options Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, - old_ordering, nonvs, sci_force_enable } + old_ordering, nonvs, sci_force_enable, nobl } See Documentation/power/video.txt for information on s3_bios and s3_mode. s3_beep is for debugging; it makes the PC's speaker beep @@ -239,6 +238,9 @@ sci_force_enable causes the kernel to set SCI_EN directly on resume from S1/S3 (which is against the ACPI spec, but some broken systems don't work without it). + nobl causes the internal blacklist of systems known to + behave incorrectly in some ways with respect to system + suspend and resume to be ignored (use wisely). acpi_use_timer_override [HW,ACPI] Use timer override. For some broken Nvidia NF5 boards @@ -314,7 +316,7 @@ amijoy.map= [HW,JOY] Amiga joystick support Map of devices attached to JOY0DAT and JOY1DAT Format: <a>,<b> - See also Documentation/input/joystick.txt + See also Documentation/input/joydev/joystick.rst analog.map= [HW,JOY] Analog joystick and gamepad support Specifies type or capabilities of an analog joystick @@ -328,11 +330,15 @@ not play well with APC CPU idle - disable it if you have APC and your system crashes randomly. - apic= [APIC,X86-32] Advanced Programmable Interrupt Controller + apic= [APIC,X86] Advanced Programmable Interrupt Controller Change the output verbosity whilst booting 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] External NMI delivery setting Format: { bsp (default) | all | none } @@ -439,7 +445,7 @@ bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) bttv.radio= Most important insmod options are available as kernel args too. - bttv.pll= See Documentation/video4linux/bttv/Insmod-options + bttv.pll= See Documentation/media/v4l-drivers/bttv.rst bttv.tuner= bulk_remove=off [PPC] This parameter disables the use of the pSeries @@ -640,9 +646,23 @@ console=brl,ttyS0 For now, only VisioBraille is supported. + console_msg_format= + [KNL] Change console messages format + default + By default we print messages on consoles in + "[time stamp] text\n" format (time stamp may not be + printed, depending on CONFIG_PRINTK_TIME or + `printk_time' param). + syslog + Switch to syslog format: "<%u>[time stamp] text\n" + IOW, each message will have a facility and loglevel + prefix. The format is similar to one used by syslog() + syscall, or to executing "dmesg -S --raw" or to reading + from /proc/kmsg. + consoleblank= [KNL] The console blank (screen saver) timeout in - seconds. Defaults to 10*60 = 10mins. A value of 0 - disables the blank timer. + seconds. A value of 0 disables the blank timer. + Defaults to 0. coredump_filter= [KNL] Change the default value for @@ -724,7 +744,7 @@ db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port (one device per port) Format: <port#>,<type> - See also Documentation/input/joystick-parport.txt + See also Documentation/input/devices/joystick-parport.rst ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot time. See @@ -854,7 +874,7 @@ The filter can be disabled or changed to another driver later using sysfs. - drm_kms_helper.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] + drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] Broken monitors, graphic adapters, KVMs and EDIDless panels may send no or incorrect EDID data sets. This parameter allows to specify an EDID data sets @@ -911,9 +931,12 @@ earlycon= [KNL] Output early console device and options. - When used with no options, the early console is - determined by the stdout-path property in device - tree's chosen node. + [ARM64] The early console is determined by the + stdout-path property in device tree's chosen node, + or determined by the ACPI SPCR table. + + [X86] When used with no options the early console is + determined by the ACPI SPCR table. cdns,<addr>[,options] Start an early, polled-mode console on a Cadence @@ -1220,7 +1243,7 @@ [HW,JOY] Multisystem joystick and NES/SNES/PSX pad support via parallel port (up to 5 devices per port) Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> - See also Documentation/input/joystick-parport.txt + See also Documentation/input/devices/joystick-parport.rst gamma= [HW,DRM] @@ -1713,6 +1736,13 @@ irqaffinity= [SMP] Set the default irq affinity mask The argument is a cpu list, as described above. + irqchip.gicv2_force_probe= + [ARM, ARM64] + Format: <bool> + Force the kernel to look for the second 4kB page + of a GICv2 controller even if the memory range + exposed by the device tree is too small. + irqfixup [HW] When an interrupt is not handled search all handlers for it. Intended to get systems with badly broken @@ -1727,20 +1757,33 @@ isapnp= [ISAPNP] Format: <RDP>,<reset>,<pci_scan>,<verbosity> - isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. - The argument is a cpu list, as described above. + isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance. + [Deprecated - use cpusets instead] + Format: [flag-list,]<cpu-list> + + Specify one or more CPUs to isolate from disturbances + specified in the flag list (default: domain): + + nohz + Disable the tick when a single task runs. + domain + Isolate from the general SMP balancing and scheduling + algorithms. Note that performing domain isolation this way + is irreversible: it's not possible to bring back a CPU to + the domains once isolated through isolcpus. It's strongly + advised to use cpusets instead to disable scheduler load + balancing through the "cpuset.sched_load_balance" file. + It offers a much more flexible interface where CPUs can + move in and out of an isolated set anytime. + + You can move a process onto or off an "isolated" CPU via + the CPU affinity syscalls or cpuset. + <cpu number> begins at 0 and the maximum value is + "number of CPUs in system - 1". + + The format of <cpu-list> is described above. - This option can be used to specify one or more CPUs - to isolate from the general SMP balancing and scheduling - algorithms. You can move a process onto or off an - "isolated" CPU via the CPU affinity syscalls or cpuset. - <cpu number> begins at 0 and the maximum value is - "number of CPUs in system - 1". - This option is the preferred way to isolate CPUs. The - alternative -- manually setting the CPU mask of all - tasks in the system -- can cause problems and - suboptimal load balancer performance. iucv= [HW,NET] @@ -1766,7 +1809,7 @@ ivrs_acpihid[00:14.5]=AMD0020:0 js= [HW,JOY] Analog joystick - See Documentation/input/joystick.txt. + See Documentation/input/joydev/joystick.rst. nokaslr [KNL] When CONFIG_RANDOMIZE_BASE is set, this disables @@ -1841,13 +1884,6 @@ Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, the default is off. - kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode - Valid arguments: 0, 1, 2 - kmemcheck=0 (disabled) - kmemcheck=1 (enabled) - kmemcheck=2 (one-shot mode) - Default: 2 (one-shot mode) - kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. Default is 0 (don't ignore, but inject #GP) @@ -1874,6 +1910,10 @@ [KVM,ARM] Trap guest accesses to GICv3 common system registers + kvm-arm.vgic_v4_enable= + [KVM,ARM] Allow use of GICv4 for direct injection of + LPIs. + kvm-intel.ept= [KVM,Intel] Disable extended page tables (virtualized MMU) support on capable Intel chips. Default is 1 (enabled) @@ -2029,9 +2069,6 @@ This tests the locking primitive's ability to transition abruptly to and from idle. - locktorture.torture_runnable= [BOOT] - Start locktorture running at boot time. - locktorture.torture_type= [KNL] Specify the locking implementation to test. @@ -2248,10 +2285,10 @@ s2idle - Suspend-To-Idle shallow - Power-On Suspend or equivalent (if supported) deep - Suspend-To-RAM or equivalent (if supported) - See Documentation/power/states.txt. + See Documentation/admin-guide/pm/sleep-states.rst. meye.*= [HW] Set MotionEye Camera parameters - See Documentation/video4linux/meye.txt. + See Documentation/media/v4l-drivers/meye.rst. mfgpt_irq= [IA-32] Specify the IRQ to use for the Multi-Function General Purpose Timers on AMD Geode @@ -2518,6 +2555,9 @@ This is useful when you use a panic=... timeout and need the box quickly up again. + These settings can be accessed at runtime via + the nmi_watchdog and hardlockup_panic sysctls. + netpoll.carrier_timeout= [NET] Specifies amount of time (in seconds) that netpoll should wait for a carrier. By default netpoll @@ -2548,6 +2588,9 @@ noalign [KNL,ARM] + noaltinstr [S390] Disables alternative instructions patching + (CPU alternatives feature). + noapic [SMP,APIC] Tells the kernel to not make use of any IOAPICs that may be present in the system. @@ -2599,6 +2642,11 @@ nosmt [KNL,S390] Disable symmetric multithreading (SMT). Equivalent to smt=1. + nospectre_v2 [X86] Disable all mitigations for the Spectre variant 2 + (indirect branch prediction) vulnerability. System may + allow data leaks with this option, which is equivalent + to spectre_v2=off. + 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. @@ -2639,7 +2687,7 @@ Valid arguments: on, off Default: on - nohz_full= [KNL,BOOT] + nohz_full= [KNL,BOOT,SMP,ISOL] The argument is a cpu list, as described above. In kernels built with CONFIG_NO_HZ_FULL=y, set the specified list of CPUs whose tick will be stopped @@ -2713,8 +2761,6 @@ norandmaps Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space - noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops - noreplace-smp [X86-32,SMP] Don't replace SMP instructions with UP alternatives @@ -3071,6 +3117,12 @@ pcie_scan_all Scan all possible PCIe devices. Otherwise we only look for one device below a PCIe downstream port. + big_root_window Try to add a big 64bit memory window to the PCIe + root complex on AMD CPUs. Some GFX hardware + can resize a BAR to allow access to all VRAM. + Adding the window is slightly risky (it may + conflict with unreported devices), so this + taints the kernel. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power Management. @@ -3134,7 +3186,7 @@ plip= [PPT,NET] Parallel port network link Format: { parport<nr> | timid | 0 } - See also Documentation/parport.txt. + See also Documentation/admin-guide/parport.rst. pmtmr= [X86] Manual setup of pmtmr I/O Port. Override pmtimer IOPort with a hex value. @@ -3185,6 +3237,10 @@ allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). There is some performance impact when enabling this. + ppc_tm= [PPC] + Format: {"off"} + Disable Hardware Transactional Memory + print-fatal-signals= [KNL] debug: print fatal signals @@ -3223,13 +3279,15 @@ instead using the legacy FADT method profile= [KNL] Enable kernel profiling via /proc/profile - Format: [schedule,]<number> + Format: [<profiletype>,]<number> + Param: <profiletype>: "schedule", "sleep", or "kvm" + [defaults to kernel profiling] Param: "schedule" - profile schedule points. - Param: <number> - step/bucket size as a power of 2 for - statistical time based profiling. Param: "sleep" - profile D-state sleeping (millisecs). Requires CONFIG_SCHEDSTATS Param: "kvm" - profile VM exits. + Param: <number> - step/bucket size as a power of 2 for + statistical time based profiling. prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk before loading. @@ -3253,6 +3311,21 @@ pt. [PARIDE] See Documentation/blockdev/paride.txt. + pti= [X86_64] Control Page Table Isolation of user and + kernel address spaces. Disabling this feature + removes hardening, but improves performance of + system calls and interrupts. + + on - unconditionally enable + off - unconditionally disable + auto - kernel detects whether your CPU model is + vulnerable to issues that PTI mitigates + + Not specifying this option is equivalent to pti=auto. + + nopti [X86_64] + Equivalent to pti=off + pty.legacy_count= [KNL] Number of legacy pty's. Overwrites compiled-in default number. @@ -3430,9 +3503,6 @@ the same as for rcuperf.nreaders. N, where N is the number of CPUs - rcuperf.perf_runnable= [BOOT] - Start rcuperf running at boot time. - rcuperf.perf_type= [KNL] Specify the RCU implementation to test. @@ -3539,6 +3609,9 @@ rcutorture.stall_cpu_holdoff= [KNL] Time to wait (s) after boot before inducing stall. + rcutorture.stall_cpu_irqsoff= [KNL] + Disable interrupts while stalling if set. + rcutorture.stat_interval= [KNL] Time (s) between statistics printk()s. @@ -3563,9 +3636,6 @@ Test RCU's dyntick-idle handling. See also the rcutorture.shuffle_interval parameter. - rcutorture.torture_runnable= [BOOT] - Start rcutorture running at boot time. - rcutorture.torture_type= [KNL] Specify the RCU implementation to test. @@ -3623,7 +3693,8 @@ rdt= [HW,X86,RDT] Turn on/off individual RDT features. List is: - cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, mba. + cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp, + mba. E.g. to turn on cmt and turn off mba use: rdt=cmt,!mba @@ -3643,7 +3714,11 @@ [KNL, SMP] Set scheduler's default relax_domain_level. See Documentation/cgroup-v1/cpusets.txt. - reserve= [KNL,BUGS] Force the kernel to ignore some iomem area + reserve= [KNL,BUGS] Force kernel to ignore I/O ports or memory + Format: <base1>,<size1>[,<base2>,<size2>,...] + Reserve I/O ports or memory so the kernel won't use + them. If <base> is less than 0x10000, the region + is assumed to be I/O ports; otherwise it is memory. reservetop= [X86-32] Format: nn[KMG] @@ -3885,6 +3960,12 @@ [KNL] Should the soft-lockup detector generate panics. Format: <integer> + A nonzero value instructs the soft-lockup detector + to panic the machine when a soft-lockup occurs. This + is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC + which is the respective build-time switch to that + functionality. + softlockup_all_cpu_backtrace= [KNL] Should the soft-lockup detector generate backtraces on all cpus. @@ -3893,6 +3974,29 @@ sonypi.*= [HW] Sony Programmable I/O Control Device driver See Documentation/laptops/sonypi.txt + spectre_v2= [X86] Control mitigation of Spectre variant 2 + (indirect branch speculation) vulnerability. + + on - unconditionally enable + off - unconditionally disable + auto - kernel detects whether your CPU model is + vulnerable + + Selecting 'on' will, and 'auto' may, choose a + mitigation method at run time according to the + CPU, the available microcode, the setting of the + CONFIG_RETPOLINE configuration option, and the + compiler with which the kernel was built. + + Specific mitigations can also be selected manually: + + retpoline - replace indirect branches + retpoline,generic - google's original retpoline + retpoline,amd - AMD-specific minimal thunk + + Not specifying this option is equivalent to + spectre_v2=auto. + spia_io_base= [HW,MTD] spia_fio_base= spia_pedr= @@ -4194,12 +4298,15 @@ Used to run time disable IRQ_TIME_ACCOUNTING on any platforms where RDTSC is slow and this accounting can add overhead. + [x86] unstable: mark the TSC clocksource as unstable, this + marks the TSC unconditionally unstable at bootup and + avoids any further wobbles once the TSC watchdog notices. turbografx.map[2|3]= [HW,JOY] TurboGraFX parallel port interface Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> - See also Documentation/input/joystick-parport.txt + See also Documentation/input/devices/joystick-parport.rst udbg-immortal [PPC] When debugging early kernel crashes that happen after console_init() and before a proper |