The Rare Glitch Project: Verification Tools for Embedded Systems

1. The Rare Glitch Project:Verification Tools for Embedded Systems Carnegie Mellon UniversityPittsburgh, PA Ed Clarke, David Garlan, Bruce Krogh, Reid Simmons, Jeannette Wing

2. Embedded Systems • They are highly distributed, multi-task, concurrent real-time systems. • They control increasingly sophisticated physical systems. • They operate with increasing autonomyunder adverse and unpredictable conditions. • They eventually will be seamlessly woven into the fabric of our everyday lives.

3. Verification • Grand Challenge • To ensure the correctness of these embedded systems as they operate in increasingly complex environments—for the safety and good of the general public. • Opportunity • State of the art verification tools are well suited for control systems. • Embedded systems have narrow hardware/software interface. • Embedded systems architectures are simpler and more regular. • Feasibility • We are not trying to solve the whole verification problem, but one for a class of systems for which we believe we can make the next big success story.

4. Our Long-Term Vision • To provide design engineers with lightweight “push-button” tools, each checking a specific application-specific property. Check Restart Check Deadlock Check Race Check Powerusage Check Fuel usage

5. Three Main Thrusts of Our Project • Verifying system integrity • Synchronization constraints • Resource constraints • Real-time constraints • Modeling the environment • Hybrid dynamics • Stochastic models • Usability • Extracting models • Explaining tool feedback system environment

6. Technical Challenges • Interleavings of multiple task executions • Inter-task dependencies and synchronization requirements • System resource constraints • Hard real-time constraints • Interactions with complex physical dynamic systems • Adverse, unpredictable environments • Stringent requirements for autonomy, fault tolerance, and survivability

7. Design Engineer’s Verification Toolbox Usability System Integrity Properties Modeling the Environment System-Environment Interactions: Hybrid Dynamics Modeling Uncertainty: Stochastic Models Synchronization Constraints Resource Constraints Real-time Constraints Foundational Building Blocks Model checking techniques and toolsTask-level system architecture, task executive languagesContinuous dynamics, quantitative analysis, reliability analysis Technical Approach Embedded System Environment

8. Cross-Cutting Themes • Exploit model checking techniques and tools. • Focus on the task level. • Incorporate continuous domains in our models.

9. Verifying System Integrity • Synchronization constraints • Publish-subscribe architecture • Cyclic-tasks with shared variables • Research question:How can we reason about their aggregate behavior? • Resource constraints • Continuous, consumable (e.g., fuel) and renewable (e.g., bandwidth, disk space) resources • Research question:How should we specify and verify resource constraints? • Real-time constraints • Quantitative timing analysis • Research questions:How can we extend this technique to continuous time? How can we deal with dynamic process creation and deletion?

10. Modeling the Environment • Hybrid dynamics • Dealing with both discrete and continuous state variables • Research question:How can we automate and scale differential equations models for large systems? • Stochastic models • Dealing with uncertainty, unpredictability • Using continuous variables (e.g., probabilities) for reliability and cost-benefit analyses • Research questions:How can we handle dependent events, cascading of events? Both nondeterministic and probabilistic state transitions?

11. Usability • Extracting models • Synchronization skeletons • Translators for task execution languages • Research question:How can we balance expressibility of languages with efficiency of verification and user-friendliness? • Explaining verification tool results • Adopt AI techniques to explain counterexamples for task executive programs. • Develop techniques to view and browse the temporal evolution of counterexamples. • Research question:How can we create virtual execution traces that can be used by existing visualization tools?

12. Checkmate Reliability and Cost Analyzers Specification Prism Counter-examples SMV Explanation Generator Model PVS Abstraction/Refinement Processor Symp … … The Rare Glitch Tool Suite Checkers and Provers Analysis Engines Specification and Modeling Languages

13. Preliminary Planning • Technical • So far: Technical presentations of our current work • To do • Identification of case studies • Identification of common group project • Continue to pursue existing two-way and three-way collaborations • Administrative • Weekly project meetings, project name, project web page

14. Project Administration • Principal Investigators • Ed Clarke, David Garlan, Bruce Krogh, Reid Simmons, Jeannette Wing (POC) • Industrial connections • Honeywell Technology Center • CMU High Dependability Computing Consortium • Years 3 and 5 • Hold workshops for technical exchange with industry

15. Preview of This Afternoon’s Talks • Ed Clarke • Verifying Bus Protocol Standards for Embedded Systems • Bruce Krogh • Model Checking for Hybrid Systems • Jeannette Wing • Scenario Graph Generation and MDP-Based Analysis • David Garlan • Model Checking Publish-Subscribe Software Architectures