CA-BIST for asynchronous circuits: a case study on the RAPPID asynchronous instruction length decoder

Journal ArticleThis paper presents a case study in low-cost noninvasive Built-In Self Test (BIST) for RAPPID, a largescale 120,000-transistor asynchronous version of the Pentium® Pro Instruction Length Decoder, which runs at 3.6 GHz. RAPPID uses a synchronous 0.25 micron CMOS library for static and domino logic, and has no Design-for-Test hooks other than some debug features. We explore the use of Cellular Automata (CA) for on-chip test pattern generation and response evaluation. More specifically, we look for fast ways to tune the CA-BIST to the RAPPID design, rather than using pseudo-random testing. The metric for tuning the CA-BIST pattern generation is based on an abstract hardware description model of the instruction length decoder, which is independent of implementation details, and hence also independent of the asynchronous circuit style. Our CA-BI ST solution uses a novel bootstrap procedure for generating the test patterns, which give complete coverage for this metric, and cover 94% of the testable stuck-at faults for the actual design at switch level. Analysis of the undetected and untestable faults shows that the same fault effects can be expected for a similar clocked circuit. This is encouraging evidence that testability is no excuse to avoid asynchronous design techniques in addition to high-performance synchronous solutions

CA-BIST for asynchronous circuits: a case study on the RAPPID asynchronous instruction length decoder

Journal ArticleThis paper presents a case study in low-cost noninvasive Built-In Self Test (BIST) for RAPPID, a largescale 120,000-transistor asynchronous version of the Pentium® Pro Instruction Length Decoder, which runs at 3.6 GHz. RAPPID uses a synchronous 0.25 micron CMOS library for static and domino logic, and has no Design-for-Test hooks other than some debug features. We explore the use of Cellular Automata (CA) for on-chip test pattern generation and response evaluation. More specifically, we look for fast ways to tune the CA-BIST to the RAPPID design, rather than using pseudo-random testing. The metric for tuning the CA-BIST pattern generation is based on an abstract hardware description model of the instruction length decoder, which is independent of implementation details, and hence also independent of the asynchronous circuit style. Our CA-BI ST solution uses a novel bootstrap procedure for generating the test patterns, which give complete coverage for this metric, and cover 94% of the testable stuck-at faults for the actual design at switch level. Analysis of the undetected and untestable faults shows that the same fault effects can be expected for a similar clocked circuit. This is encouraging evidence that testability is no excuse to avoid asynchronous design techniques in addition to high-performance synchronous solutions

Automated Hardware Prototyping for 3D Network on Chips

Vor mehr als 50 Jahren stellte Intel® Mitbegründer Gordon Moore eine Prognose zum Entwicklungsprozess der Transistortechnologie auf. Er prognostizierte, dass sich die Zahl der Transistoren in integrierten Schaltungen alle zwei Jahre verdoppeln wird. Seine Aussage ist immer noch gültig, aber ein Ende von Moores Gesetz ist in Sicht. Mit dem Ende von Moore’s Gesetz müssen neue Aspekte untersucht werden, um weiterhin die Leistung von integrierten Schaltungen zu steigern. Zwei mögliche Ansätze für "More than Moore” sind 3D-Integrationsverfahren und heterogene Systeme. Gleichzeitig entwickelt sich ein Trend hin zu Multi-Core Prozessoren, basierend auf Networks on chips (NoCs). Neben dem Ende des Mooreschen Gesetzes ergeben sich bei immer kleiner werdenden Technologiegrößen, vor allem jenseits der 60 nm, neue Herausforderungen. Eine Schwierigkeit ist die Wärmeableitung in großskalierten integrierten Schaltkreisen und die daraus resultierende Überhitzung des Chips. Um diesem Problem in modernen Multi-Core Architekturen zu begegnen, muss auch die Verlustleistung der Netzwerkressourcen stark reduziert werden. Diese Arbeit umfasst eine durch Hardware gesteuerte Kombination aus Frequenzskalierung und Power Gating für 3D On-Chip Netzwerke, einschließlich eines FPGA Prototypen. Dafür wurde ein Takt-synchrones 2D Netzwerk auf ein dreidimensionales asynchrones Netzwerk mit mehreren Frequenzbereichen erweitert. Zusätzlich wurde ein skalierbares Online-Power-Management System mit geringem Ressourcenaufwand entwickelt. Die Verifikation neuer Hardwarekomponenten ist einer der zeitaufwendigsten Schritte im Entwicklungsprozess hochintegrierter digitaler Schaltkreise. Um diese Aufgabe zu beschleunigen und um eine parallele Softwareentwicklung zu ermöglichen, wurde im Rahmen dieser Arbeit ein automatisiertes und benutzerfreundliches Tool für den Entwurf neuer Hardware Projekte entwickelt. Eine grafische Benutzeroberfläche zum Erstellen des gesamten Designablaufs, vom Erstellen der Architektur, Parameter Deklaration, Simulation, Synthese und Test ist Teil dieses Werkzeugs. Zudem stellt die Größe der Architektur für die Erstellung eines Prototypen eine besondere Herausforderung dar. Frühere Arbeiten haben es versäumt, eine schnelles und unkompliziertes Prototyping, insbesondere von Architekturen mit mehr als 50 Prozessorkernen, zu realisieren. Diese Arbeit umfasst eine Design Space Exploration und FPGA-basierte Prototypen von verschiedenen 3D-NoC Implementierungen mit mehr als 80 Prozessoren

Android Application Development for the Intel Platform

Computer scienc

Android on x86

Computer scienc

Machine Learning for Microprocessor Performance Bug Localization

The validation process for microprocessors is a very complex task that consumes substantial engineering time during the design process. Bugs that degrade overall system performance, without affecting its functional correctness, are particularly difficult to debug given the lack of a golden reference for bug-free performance. This work introduces two automated performance bug localization methodologies based on machine learning that aims to aid the debugging process. Our results show that, the evaluated microprocessor core performance bugs whose average IPC impact is greater than 1%, our best-performing technique is able to localize the exact microarchitectural unit of the bug $\sim$77\% of the time, while achieving a top-3 unit accuracy (out of 11 possible locations) of over 90% for bugs with the same average IPC impact. The proposed system in our simulation setup requires only a few seconds to perform a bug location inference, which leads to a reduced debugging time.Comment: 12 pages, 6 figure

CustomProcessingUnit: Reverse Engineering and Customization of Intel Microcode

Microcode provides an abstraction layer over the instruction set to decompose complex instructions into simpler micro-operations that can be more easily implemented in hardware. It is an essential optimization to simplify the design of x86 processors. However, introducing an additional layer of software beneath the instruction set poses security and reliability concerns. The microcode details are confidential to the manufacturers, preventing independent auditing or customization of the microcode. Moreover, microcode patches are signed and encrypted to prevent unauthorized patching and reverse engineering. However, recent research has recovered decrypted microcode and reverse-engineered read/write debug mechanisms on Intel Goldmont (Atom), making analysis and customization of microcode possible on a modern Intel microarchitecture. In this work, we present the first framework for static and dynamic analysis of Intel microcode. Building upon prior research, we reverse-engineer Goldmont microcode semantics and reconstruct the patching primitives for microcode customization. For static analysis, we implement a Ghidra processor module for decompilation and analysis of decrypted microcode. For dynamic analysis, we create a UEFI application that can trace and patch microcode to provide complete microcode control on Goldmont systems. Leveraging our framework, we reverse-engineer the confidential Intel microcode update algorithm and perform the first security analysis of its design and implementation. In three further case studies, we illustrate the potential security and performance benefits of microcode customization. We provide the first x86 Pointer Authentication Code (PAC) microcode implementation and its security evaluation, design and implement fast software breakpoints that are more than 1000x faster than standard breakpoints, and present constant-time microcode division, illustrating the potential security and performance benefits of microcode customization

Application development process for GNAT, a SOC networked system

The market for smart devices was identified years ago, and yet commercial progress into this field has not made significant progress. The reason such devices are so painfully slow to market is that the gap between the technologically possible and the market capitalizable is too vast. In order for inventions to succeed commercially, they must bridge the gap to tomorrow\u27s technology with marketability today. This thesis demonstrates a design methodology that enables such commercial success for one variety of smart device, the Ambient Intelligence Node (AIN). Commercial Off-The Shelf (COTS) design tools allowing a Model-Driven Architecture (MDA) approach are combined via custom middleware to form an end-to-end design flow for rapid prototyping and commercialization. A walkthrough of this design methodology demonstrates its effectiveness in the creation of Global Network Academic Test (GNAT), a sample AIN. It is shown how designers are given the flexibility to incorporate IP Blocks available in the Global Economy to reduce Time-To-Market and cost. Finally, new kinds of products and solutions built on the higher levels of design abstraction permitted by MDA design methods are explored

Architectures for dependable modern microprocessors

Η εξέλιξη των ολοκληρωμένων κυκλωμάτων σε συνδυασμό με τους αυστηρούς χρονικούς περιορισμούς καθιστούν την επαλήθευση της ορθής λειτουργίας των επεξεργαστών μία εξαιρετικά απαιτητική διαδικασία. Με κριτήριο το στάδιο του κύκλου ζωής ενός επεξεργαστή, από την στιγμή κατασκευής των πρωτοτύπων και έπειτα, οι τεχνικές ελέγχου ορθής λειτουργίας διακρίνονται στις ακόλουθες κατηγορίες: (1) Silicon Debug: Τα πρωτότυπα ολοκληρωμένα κυκλώματα ελέγχονται εξονυχιστικά, (2) Manufacturing Testing: ο τελικό ποιοτικός έλεγχος και (3) In-field verification: Περιλαμβάνει τεχνικές, οι οποίες διασφαλίζουν την λειτουργία του επεξεργαστή σύμφωνα με τις προδιαγραφές του. Η διδακτορική διατριβή προτείνει τα ακόλουθα: (1) Silicon Debug: Η εργασία αποσκοπεί στην επιτάχυνση της διαδικασίας ανίχνευσης σφαλμάτων και στον αυτόματο εντοπισμό τυχαίων προγραμμάτων που δεν περιέχουν νέα -χρήσιμη- πληροφορία σχετικά με την αίτια ενός σφάλματος. Η κεντρική ιδέα αυτής της μεθόδου έγκειται στην αξιοποίηση της έμφυτης ποικιλομορφίας των αρχιτεκτονικών συνόλου εντολών και στην δυνατότητα από-διαμόρφωσης τμημάτων του κυκλώματος, (2) Manufacturing Testing: προτείνεται μία μέθοδο για την βελτιστοποίηση του έλεγχου ορθής λειτουργίας των πολυνηματικών και πολυπύρηνων επεξεργαστών μέσω της χρήση λογισμικού αυτοδοκιμής, (3) Ιn-field verification: Αναλύθηκε σε βάθος η επίδραση που έχουν τα μόνιμα σφάλματα σε μηχανισμούς αύξησης της απόδοσης. Επιπρόσθετα, προτάθηκαν τεχνικές για την ανίχνευση και ανοχή μόνιμων σφαλμάτων υλικού σε μηχανισμούς πρόβλεψης διακλάδωσης.Technology scaling, extreme chip integration and the compelling requirement to diminish the time-to-market window, has rendered microprocessors more prone to design bugs and hardware faults. Microprocessor validation is grouped into the following categories, based on where they intervene in a microprocessor’s lifecycle: (a) Silicon debug: the first hardware prototypes are exhaustively validated, (b) Μanufacturing testing: the final quality control during massive production, and (c) In-field verification: runtime error detection techniques to guarantee correct operation. The contributions of this thesis are the following: (1) Silicon debug: We propose the employment of deconfigurable microprocessor architectures along with a technique to generate self-checking random test programs to avoid the simulation step and triage the redundant debug sessions, (2) Manufacturing testing: We propose a self-test optimization strategy for multithreaded, multicore microprocessors to speedup test program execution time and enhance the fault coverage of hard errors; and (3) In-field verification: We measure the effect of permanent faults performance components. Then, we propose a set of low-cost mechanisms for the detection, diagnosis and performance recovery in the front-end speculative structures. This thesis introduces various novel methodologies to address the validation challenges posed throughout the life-cycle of a chip