This parameter can be used to control the NMI watchdog (i.e. the hard lockup detector) on x86 systems.
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0 Disable the hard lockup detector.
1 Enable the hard lockup detector.
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The hard lockup detector monitors each CPU for its ability to respond to timer interrupts. The mechanism utilizes CPU performance counter registers that are programmed to generate Non-Maskable Interrupts (NMIs) periodically while a CPU is busy. Hence, the alternative name ‘NMI watchdog’.
The NMI watchdog is disabled by default if the kernel is running as a guest in a KVM virtual machine. This default can be overridden by adding::
nmi_watchdog=1
to the guest kernel command line (see Documentation/admin-guide/kernel-parameters.rst).