I. Abstract Post silicon validation is a unique challenge in the design verification process. On one hand, it utilizes real silicon and is therefore able to cover a larger state-space. On the other, it suffers from debugging challenges due to a lack of observability into the design. These challenges dictate distinctive design choices, such as the simplicity of validation tools and a built-for-debugging software design methodology. The Memory Management Unit (MMU) is central to any design that uses virtual-memory, and creates complex verification challenges, especially in many-core designs. We propose a novel method for post silicon validation of the MMU that brings together previously undescribed techniques, based on several papers and patents. This method was implemented in Threadmill, a bare metal exerciser and was used in the verification of high-end industry-level POWER and ARM SoCs. It succeeded in increasing RTL coverage, hitting several hidden bugs, and saving hundreds of work-hours in the validation process.

Due to the complexity of designs, post-silicon validation remains a major challenge with few systematic solutions. We provide an overview of the state-of-the-art post silicon validation process used by IBM to verify its latest IBM POWER9 processor. During the POWER9 post-silicon validation, we detected and handled 30% more logic bugs in 80% of the time, as compared to the previous IBM POWER8 bring-up. This improvement is the result of lessons learned from previous designs, leading to numerous innovations. We provide bug analysis data and compare it to POWER8 results. We demonstrate our methodology by describing several bugs from fail detection to root cause.

Post-silicon validation has become essential in catching hard-to-detect, rarely-occurring bugs that have slipped through pre-silicon verification. Post-silicon validation flows, however, are challenged by limited signal observability, which impacts their ability of diagnosing and detecting bugs. Indeed, bug manifestations during the execution of constrained-random tests may be masked and be unobservable from the test's outputs. The ability to evaluate the bug-masking rate of a test provides great value in generating and/or selecting effective tests for high coverage regressions.

Post-silicon validation is one of the most important parts of the microprocessor prototype chip lifecycle. It is the last chance for debug engineers to detect defects and bugs that escaped pre-silicon verification, before the chip is released to the market. Effective solutions are required to harness the peak performance of the hardware prototype and evaluate whether the microprocessor chip is fully compliant with the instruction set and other specifications. We perform a comprehensive experimental study on a state-of-the-art microarchitecture to assess and identify the most difficult bugs in address translation caching arrays (multi-level TLBs and MMU Caches), and explain why these bugs persist across generations. We also categorize them into distinct bug scenarios. We then propose a novel methodology for generating random self-checking stimuli programs, which expose and detect such bug scenarios. Our experimental results show that the proposed method can detect difficult bugs that are likely to be missed by traditional post-silicon validation techniques.

It is shown that interleaved Reed–Solomon codes can be list-decoded for burst errors while attaining the generalized Reiger bound for list decoding. A respective decoding algorithm is presented that is (significantly) more efficient than a burst list decoder for a noninterleaved Reed–Solomon code with comparable parameters. Finally, it is shown through counterexamples that unlike the special case of Reed–Solomon codes, interleaving does not always preserve the list decoding properties of the constituent code.

It is shown that interleaved Reed-Solomon codes can be list-decoded for burst errors while attaining the generalized Reiger bound for list decoding.