Instance specification

The instance paths in the SDF file are relative to the instance to which the SDF is applied. Usually, this instance is an ASIC or FPGA model instantiated under a testbench. For example, to annotate maximum timing values from the SDF file myasic.sdf to an instance u1 under a top-level named testbench, invoke the simulator as follows:

vsim -sdfmax /testbench/u1=myasic.sdf testbench 

If the instance name is omitted then the SDF file is applied to the top-level. This is usually incorrect because in most cases the model is instantiated under a testbench or within a larger system level simulation. In fact, the design can have several models, each having its own SDF file. In this case, specify an SDF file for each instance. For example,

vsim -sdfmax /system/u1=asic1.sdf -sdfmax /system/u2=asic2.sdf system 

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