A double fault occurs when a fault occurs when the CPU is running the handler for a fault. In this case the CPU pauses the execution of the fault handler and jumps to the double fault handler. A double fault is usually the result of a bug in the kernel.

What is double fault exception?

On the x86 architecture, a double fault exception occurs if the processor encounters a problem while trying to service a pending interrupt or exception. An example situation when a double fault would occur is when an interrupt is triggered but the segment in which the interrupt handler resides is invalid.

What is the vector associated with the double fault exception?

A double fault behaves like a normal exception. It has the vector number 8 and we can define a normal handler function for it in the IDT.