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segfault / segmentation fault
A crash triggered when a program touches memory it isn't allowed to access.
The hardware and OS track which memory each program may use. When code reads or writes an invalid address — a null pointer, freed memory, out of bounds — the CPU raises a fault the OS reports as a segmentation fault, usually killing the process. Ideally only the offending process dies; a serious kernel bug is one where a mere userspace segfault can hang the whole machine.
See also
- serial portA very simple, low-level hardware channel used to print text out of a machine one character at a time.
- schedulerThe part of an operating system that decides which thread runs on the CPU next, and switches between them.
- spinlockA lock where a CPU waiting for it just keeps re-checking in a tight loop until it's free.