Overview
An NMI is often used when response time is critical, and when an interrupt should never be disabled in the normal operation of the system. Such uses include the reporting of non-recoverable hardware errors, methods for system debugging and profiling, and special case handling such as system resets.
In modern architectures, NMIs are typically used to handle non-recoverable errors, which need immediate attention. Therefore, such interrupts should not be masked in the normal operation of the system. These errors include non-recoverable internal system chipset errors, corruption in system memory such as parity and ECC errors, and data corruption detected on system and peripheral busses.
On some systems, an NMI can be triggered by the computer's user. Such applications include hardware and software debugging interfaces, and system reset buttons.
Debugging NMIs are typically used to diagnose and fix faulty code. In such cases an NMI is used to execute an interrupt handler that transfers control to a special monitor program. From this program a developer can inspect the machine's memory, and examine the internal state of the program at the instant of its interruption. Such NMIs also allow computers which appear to be hung to be debugged or diagnosed.
Read more about this topic: Non-maskable Interrupt