Maskable vs Non-Maskable Interrupts: Key Differences Explained
Maskable interrupts are CPU signals that software can temporarily ignore; Non-Maskable interrupts (NMIs) force the processor to act immediately, no exceptions.
Confusion arises because both are “interrupts”—yet mixing them is like ignoring a fire alarm versus the building actually burning. When your laptop freezes, developers toggle maskable ones for smooth multitasking; NMIs, however, signal critical hardware faults that even the OS cannot hush.
Key Differences
Maskable: software-controllable, lower priority, used for keyboard, mouse, timers. Non-Maskable: hardware-triggered, highest priority, reserved for RAM parity, watchdog, thermal shutdown.
Which One Should You Choose?
You don’t choose; the hardware does. Developers mask interrupts to avoid glitches; engineers design NMIs for catastrophic events. Know both to debug crashes without bricking devices.
Can an NMI be disabled?
No. By design, NMIs bypass any software mask to guarantee immediate attention.
Why does my game lag when USB is plugged in?
USB events are maskable; if the driver masks them too long, frame drops occur until the interrupt is serviced.
Are NMIs used in smartphones?
Rarely. Mobile SoCs rely on secure watchdogs and thermal sensors that trigger NMIs only during critical battery or overheating failures.