Emulating a System on Chip(SoC): Verification and Validation

The ever-growing complexity of System on Chips (SoCs) necessitates robust verification and validation methodologies to ensure their functionality and performance. Emulation plays a pivotal role in this process, enabling engineers to create a virtual prototype of the SoC and stimulate it with realistic workloads. This article delves into the intricacies of SoC emulation, exploring verification and validation techniques employed to guarantee a functional and reliable SoC design.

Understanding System on Chips (SoCs)

An SoC integrates various processing elements, memory blocks, peripherals, and communication interfaces onto a single chip. These elements work in concert to execute specific tasks, forming the core of many modern electronic devices, ranging from smartphones to automobiles. The intricate interactions between these components necessitate thorough verification and validation to unearth potential design flaws before SoC fabrication.

The Role of Emulation in SoC Design

Emulation bridges the gap between hardware description languages (HDLs) and physical hardware. It creates a virtual replica of the SoC on a high-performance computing platform, enabling engineers to execute software instructions and observe the system's behavior. This virtual environment allows for comprehensive testing under diverse scenarios before committing to expensive silicon fabrication.

Verification vs. Validation: Distinct Goals

Verification and validation, though often used interchangeably, serve distinct purposes in the SoC design cycle.

• Verification ensures the SoC adheres to its design specifications. It focuses on functional correctness, verifying that the SoC operates as intended and produces the anticipated outputs for a given set of inputs.
• Validation ascertains that the SoC meets the system-level requirements. It emphasizes real-world functionality, validating if the SoC performs its intended function within the broader system context.

Emulation-Based Verification Techniques

Emulation facilitates various verification techniques to guarantee the SoC's functional integrity.

1. Instruction Set Simulation (ISS): An ISS emulates the instruction set architecture (ISA) of the processor core within the SoC. It executes machine code instructions cycle-by-cycle, mimicking the processor's behavior and enabling the verification of instruction decoding, execution, and pipeline functionality.
2. Functional Verification: This technique utilizes testbenches to stimulate the SoC with controlled inputs and evaluate its outputs against pre-defined expectations. Emulation allows for the creation of complex testbenches that generate realistic workloads and expose the SoC to various corner-case scenarios.
3. Bus Functional Verification: This method focuses on verifying the communication protocols between different SoC components. Emulation enables the simulation of bus transactions, ensuring data integrity and proper synchronization between interconnected components.
4. Coverage Analysis: Coverage tools track the execution of verification scenarios to identify areas of the design that haven't been exercised. Emulation allows for comprehensive coverage analysis, ensuring that all critical functionalities and corner cases have been adequately tested.

Emulation-Aided Validation Strategies

Emulation extends its value beyond verification by supporting system-level validation activities.

1. Bootloader and OS Validation: Emulation provides a platform to validate the boot sequence, device drivers, and operating system functionality on the emulated SoC. This enables early identification of software compatibility issues and ensures seamless integration between hardware and software components.
2. Performance Validation: Emulation facilitates performance analysis by executing real-world workloads and measuring key performance metrics like throughput, latency, and power consumption. This allows engineers to identify performance bottlenecks and optimize the SoC design for desired performance targets.
3. Integration Validation: Emulation can be leveraged to integrate the SoC with its surrounding environment, including memory, peripherals, and other system components. This enables early validation of system-level interactions and exposes potential integration challenges before physical hardware becomes available.

Challenges and Considerations in Emulation-Based Verification and Validation

While emulation offers significant benefits, there are challenges to consider:

• Emulation Speed: Emulation typically runs slower than real hardware, extending the verification and validation process. Techniques like hardware-assisted emulation and selective emulation can mitigate this issue.
• Model Accuracy: The fidelity of the emulated SoC relies on the accuracy of hardware models. Inaccuracies in these models can introduce validation gaps. Rigorous model verification is crucial to ensure emulation effectiveness.
• Complexity Management: Managing the complexity of large-scale SoCs within the emulation environment can be challenging. Effective design partitioning and hierarchical emulation strategies are essential for efficient verification and validation.

Emulation using IBM Tools for SoC Verification and Validation

Building upon the foundation laid in the previous article, let's explore specific IBM tools that empower emulation-based verification and validation of SoCs.

IBM Power Systems Servers for Emulation

IBM's Power Systems servers are high-performance computing platforms that serve as ideal hosts for hardware emulation. Their superior processing power and advanced memory architecture provide the necessary resources to efficiently execute complex SoC emulation models.

Other IBM Tools for SoC Design

Beyond HVS, IBM offers a wider ecosystem of tools that complement the emulation process:

• Rational Rhapsody: This visual design tool enables the creation of executable specifications, which can be leveraged to generate test cases and stimulus for emulation.
• IBM Security Services: IBM's security expertise can be integrated with the emulation environment to assess the security posture of the SoC during the verification and validation process.

By combining HVS, Power Systems servers, and other relevant IBM tools, developers gain a comprehensive environment for SoC verification and validation using emulation. This empowers them to create robust and secure SoCs with increased confidence.

Third-party Emulation Tools: While HVS is a powerful solution, exploring third-party emulation tools can provide additional functionalities and may be better suited for specific needs.

Skills and Tools for SoC Verification and Testing:Programming Languages (C, C++, Python, etc.)Hardware Description Languages (Verilog, VHDL, SystemVerilog)Verification Methodologies (UVM, OVM, eRM)Verification Tools (simulators, emulators, formal tools, debuggers, coverage tools)Testing Standards (IEEE 1149.1, IEEE 1500, IEEE 1687)Testing Tools (ATPG tools, scan tools, fault diagnosis tools, yield analysis tools)

Conclusion

Emulation serves as a cornerstone for SoC verification and validation. By creating a virtual prototype of the SoC, it empowers engineers to comprehensively test its functionality and performance under diverse conditions. Leveraging a combination of verification and validation techniques within the emulation environment ensures a robust and reliable SoC design, paving the way for successful product development.

Glossary of terms:

SoC: An SoC (System-on-Chip) integrates various electronic components like processors, memory, and peripherals onto a single chip. This miniaturization offers advantages like reduced size, power consumption, and improved performance.

SoC Applications: SoCs are used in various devices such as smartphones, wearables, automotive systems, and medical devices.

SoC Design Process Architecture: Defines how SoC components are organized and interconnected (homogeneous, heterogeneous, or hybrid architectures).

Verification: Ensures the SoC meets specifications and functions correctly (critical phase consuming over 70% of design cycle).

Testing: Detects defects in manufactured SoCs (ensures quality and reliability).

Importance of SoC Verification: Verification catches design bugs early, reducing development costs and ensuring the SoC meets performance, power, and safety requirements.

It involves various techniques like simulation (software models), emulation (hardware platforms), formal methods (mathematical proofs), and hardware-software co-verification (testing hardware-software interaction).

Verification methodologies:

Intellectual Property core (IP) Verification: Intensive verification of IPs using techniques like formal verification and random simulation.

Sub-System Verification: Verification of subsystems comprising pre-verified IPs and newly built components.

SoC Verification: Verification of the complete SoC with pre-verified IPs and custom IPs, often using black-box verification with hardware emulation or simulation.

SoC Testing: Detecting defects and faults in manufactured SoCs.

Techniques: Design-for-Testability (DFT), Built-in Self-Test (BIST), Automatic Test Pattern Generation (ATPG), Scan Testing, Fault Diagnosis, and Yield Analysis.

Disclaimer:

The opinions expressed are those of the author and not IBM Corporation where he works. No warranties express or implied in using this material.