Functional Verification for Agile Processor Development: A Case for Workflow Integration

Agile hardware development methodology has been widely adopted over the past decade.Despite the research progress,the industry still doubts its applicability,especially for the functional verification of complicated processor chips.Functional verification commonly employs a simulation-based method of co-simulating the design under test with a reference model and checking the consistency of their outcomes given the same input stimuli.We observe limited collaboration and information exchange through the design and verification processes,dramatically leading to inefficiencies when applying the conventional functional verification workflow to agile development.In this paper,we propose workflow integration with collaborative task delegation and dynamic information exchange as the design principles to effectively address the challenges on functional verification under the agile development model.Based on workflow integration,we enhance the functional verification workflows with a series of novel methodologies and toolchains.The diff-rule based agile verification methodology(DRAV)reduces the overhead of building reference models with runtime execution information from designs under test.We present the RISC-V implementation for DRAV,DiffTest,which adopts information probes to extract internal design behaviors for co-simulation and debugging.It further integrates two plugins,namely XFUZZ for effective test generation guided by design coverage metrics and LightSSS for efficient fault analysis triggered by co-simulation mismatches.We present the integrated workflows for agile hardware development and demonstrate their effectiveness in designing and verifying RISC-V processors with 33 functional bugs found in NutShell.We also illustrate the efficiency of the proposed toolchains with a case study on a functional bug in the L2 cache of XiangShan.

CA-PLAN, a Service-Oriented Workflow

Workflow management systems (WfMSs) are accepted worldwide due to their ability to model and control business processes. Previously, we defined an intra-organizational workflow specification model, Process LANguage (PLAN). PLAN, with associated tools, allowed a user to describe a graph specification for processes, artifacts, and participants in an organization. PLAN has been successfully implemented in Agentflow to support workflow (Agentflow) applications. PLAN, and most current WfMSs are designed to adopt a centralized architecture so that they can be applied to a single organization. However, in such a structure, participants in Agentflow applications in different organizations cannot serve each other with workflows. In this paper, a service-oriented cooperative workflow model, Cooperative Agentflow Process LANguage (CA-PLAN) is presented. CA-PLAN proposes a workflow component model to model inter-organizational processes. In CA-PLAN, an inter-organizational process is partitioned into several intra-organizational processes. Each workflow system inside an organization is modeled as an Integrated Workflow Component (IWC). Each IWC contains a process service interface, specifying process services provided by an organization, in conjunction with a remote process interface specifying what remote processes are used to refer to remote process services provided by other organizations, and intra-organizational processes. An IWC is a workflow node and participant. An inter-organizational process is made up of connections among these process services and remote processes with respect to different IWCs. In this paper, the related service techniques and supporting tools provided in Agentflow systems are presented.

3D extrusion of multi-biomaterial lattices using an environmentally informed workflow

The conventional building material palette has been proven limited in terms of adaptability to our current environmental challenges. Innovations in computational design and digital manufacturing have supported the broadening of biomaterial applications as an alternative. While biomaterials are characteristically responsive to stimuli such as temperature and humidity, their unpredictable behaviour is a hurdle to standardization and architectural utilisation. To examine the nexus between material formulation, computation and manufacturing, multi-biomaterial lattice structures were produced through an environmentally informed workflow. Customized biomaterial development resulted in three candidate biopolymer blends with varying levels of hydro-responsiveness and transparency. The computational strategy included a machine learning clustering algorithm to customise results and dictate material distribution outputs. To test the workflow, environmental data of solar radiation exposure and solar heat gain from a specific location was used to inform the material deposition via pneumatic extrusion for the design and digital fabrication of a deformation-controlled prototype of 350 mm × 350 mm. This led to a series of multi-biomaterial wall panel components that can be applied at architectural scale. In future, these techniques can support the incorporation of living elements to be embedded within the built environment for truly animate architecture.