1. In a microprocessor, a method of selectively providing context switch support for extendible microprocessor logic to an operating system executing on the microprocessor, the method comprising: providing at least one software extension to the operating system, the software extension defining properties including instruction and register locations of the extendible logic and how that extendible logic may be enabled/disabled; generating a software exception when a specific extendible logic is requested; and in response to the exception, calling with the operating system the at least one software extension to perform context switching of data contained within the specific extendible logic.