Question

Some DPI imported tasks and functions require that the context of their call is known. For example, those calls can be associated with instances of C models that have a one-to-one correspondence with instances of SystemVerilog modules that are making the calls. Alternatively, a DPI imported task or function might need to access or modify simulator data structures using PLI or VPI calls, or by making a call back into SystemVerilog via an export task or function. Context knowledge is required for such calls to function properly. It can take special instrumentation of their call to provide such context.

To avoid any unnecessary overhead, imported task and function calls in SystemVerilog code are not instrumented unless the imported task or function is specified as context in its SystemVerilog import declaration. A small set of DPI utility functions are available to assist programmers when working with context tasks or functions (see Annex E.8.3). If those utility functions are used with any non-context function, a system error shall result.