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. If the processor encounters a problem when calling the double fault handler, a triple fault is generated and the processor shuts down.
As double faults can only happen due to kernel bugs, they are rarely caused by user space programs in a modern protected mode operating system, unless the program somehow gains kernel access (some viruses and also some low-level DOS programs). Other processors like PowerPC or SPARC generally save state to predefined and reserved machine registers. A double fault will then be a situation where another exception happens while the processor is still using the contents of these registers to process the exception. SPARC processors have four levels of such registers, i.e. they have a 4-window register system.
Famous quotes containing the words double and/or fault:
“... the next war will be a war in which people not armies will suffer, and our boasted, hard-earned civilization will do us no good. Cannot the women rise to this great opportunity and work now, and not have the double horror, if another war comes, of losing their loved ones, and knowing that they lifted no finger when they might have worked hard?”
—Eleanor Roosevelt (1884–1962)
“A man will teach his wife what is needed to arouse his desires. And there is no reason for a woman to know any more than what her husband is prepared to teach her. If she gets married knowing far too much about what she wants and doesn’t want then she will be ready to find fault with her husband.”
—Barbara Cartland (b. 1901)