Restarting the Simulator from a Previously-Saved Snapshot

Using the multi-step xrun invocation method, you compile your modules using xrun -compile, then you elaborate using xrun -elaborate, which elaborates only newly-compiled modules: If you have not recompiled a module, the elaborator does not re-elaborate it. The third step is to simulate using xrun -R.

When you simulate using a previously-saved snapshot, the simulator (xrun -r) verifies that the snapshot depends on modules that have a time stamp that is earlier than the snapshot itself. You can run the simulator from a previously-saved snapshot as indicated by the following use models:

Use Model 1 (Warm Restart)

1. Compile and elaborate to generate snapshot A.
2. In SimVision, simulate using snapshot A for some time (such as 1000 ns).
3. Save snapshot B (save :B).
4. Exit simulation.
5. Re-elaborate the design to generate snapshot A.

You can run xrun -R using snapshot B. If you run xrun -R using snapshot A at this point, you cannot use Tcl restart l  restart to simulate using snapshot B because snapshot A now has a newer timestamp than snapshot B. You can simulate snapshot B only from the xrun -R command line.

Use Model 2 (Cold Restart)

1. Compile and elaborate to generate snapshot A.
2. In SimVision, simulate using snapshot A for some time (such as 1000 ns).
3. Save snapshot B (save :B).
4. Exit simulation.
5. Re-elaborate the design to generate snapshot C.

You can run xrun -R using snapshot B. You can run xrun -R using snapshot A. You can also use Tcl restart to simulate using snapshot B. However, if you run xrun -R using snapshot C at this point, you cannot use Tcl restart to simulate using snapshot B because snapshot C now has a newer time stamp than snapshot B. You can simulate snapshot B only from the xrun -R command line.

Related Topics

• Using the Save-and-Restart Feature
• Mixed-Signal Activity Statistics
• Running the Simulator
• Exiting the Simulation