Survey of methods for functional online testing of microprocessors

Online testing is a process of functional verification of microprocessors produced in silicon or their FPGA-prototypes, i.e. post-silicon verification. This type of testing differs both from the manufacturing testing, aimed at checking the workability of manufactured chips (e.g., absence of physical defects, admissibility of physical characteristics) and from simulation-based pre-silicon functional verification of microprocessors models (where internal microprocessor signals are available for observing, and the execution process can be controlled). Post-silicon verification enables to rapidly run huge numbers of tests and detect bugs missed during pre-silicon functional verification. Tests for microprocessors are usually represented by executable programs. Accordingly, the main tasks of online testing are high-performance generation of test programs in the given ISA and creation of a test environment responsible for launching programs, assessing the correctness of their execution by a microprocessor, diagnosing errors, and interacting with the outside world. This paper examines the problems arising in the development of online testing systems (online test program generators), reviews existing solutions in this area, and, on the base on them, proposes a promising approach to organizing online testing.