Verification methodological manual (VMM) , co-authored by verification experts from ARM and Synopsys, describes how to use SystemVerilog to develop scalable, predictable and reusable verification environments. VMM has become important factor in increasing verification reuse, improved verification productivity and timeliness.
VMM consists coding guide lines and base classes. VMM is focused on Coverage driven verification methodology. VMM supports both the top-down and bottom-up approaches. VMM follows layered test bench architecture to take the full advantage of the automation. The VMM for SystemVerilog TestBench architecture comprises five layers.
The layered TestBench is the heart of the verification environment in VMM:
This layer connects the TestBench to the RTL design. It consists of interface, clocking, and modport constructs.
This layer contains lower-level driver and monitor components, as well as the assertions. This layer provides a transaction-level interface to the layer above and drives the physical pins via the signal layer.
This layer contains higher-level driver and monitor components, as well as the self-checking structure (scoreboard/tracker).
This layer uses generators to produce streams or sequences of transactions that are applied to the functional layer. The generators have a set of weights, constraints or scenarios specified by the test layer. The randomness of constrained-random testing is introduced within this layer.
Tests are located in this layer. Test layer can interact with all the layers. This layer allows to pass directed commands to functional and command layer.
The VMM Standard Library provides base classes for key aspects of the verification environment, transaction generation, notification service and a message logging service.
These libraries can be downloaded from http://www.vmmcentral.org Following are some of the classes and macros defined in the VMM Standard Library
The class is a base class used to implement verification environments.
This base class is to be used as the basis for all transactors, including bus-functional models, monitors and generators. It provides a standard control mechanism expected to be found in all transactors.
This class implements a generic transaction-level interface mechanism. Transaction-level interfaces remove the higher-level layers from the physical interface details. Using channels, transactors pass transactions from one to other.
This base class is to be used as the basis for all transaction descriptors and data models. It provides a standard set of methods expected to be found in all descriptors. User must extend vmm_data to create a custom transaction.
The vmm_log class used implements an interface to the message service. These classes provide a mechanism for reporting simulation activity to a file or a terminal. To ensure a consistent look and feel to the messages issued from different sources, vmm_log is used.
This is a macro. This macro defines a atomic generator for generating transaction which are derived from vmm_data.
Defines a scenario generator class to generate sequences of related instances of the specified class.
The vmm_notify class implements an interface to the notification service. The notification service provides a synchronization mechanism for concurrent threads or transactors.
This class will be useful for runtime selection of testcases to run on an environment.