Simulation Runtime Arguments

The following are the arguments that may be passed to a Verilated executable, provided that executable calls VerilatedContext*->commandArgs(argc, argv).

All simulation runtime arguments begin with “+verilator”, so that the user’s executable may skip over all “+verilator” arguments when parsing its command line.


+verilator+debug                  Enable debugging
+verilator+debugi+<value>         Enable debugging at a level
+verilator+error+limit+<value>    Set error limit
+verilator+help                   Display help
+verilator+noassert               Disable assert checking
+verilator+prof+exec+file+<filename>  Set execution profile filename
+verilator+prof+exec+start+<value>    Set execution profile starting point
+verilator+prof+exec+window+<value>   Set execution profile duration
+verilator+prof+vlt+file+<filename>   Set PGO profile filename
+verilator+rand+reset+<value>     Set random reset technique
+verilator+seed+<value>           Set random seed
+verilator+V                      Verbose version and config
+verilator+version                Show version and exit

Enable simulation runtime debugging. Equivalent to +verilator+debugi+4.


Enable simulation runtime debugging at the provided level.


Set number of non-fatal errors (e.g. assertion failures) before exiting simulation runtime. Also affects number of $stop calls needed before exit. Defaults to 1.


Display help and exit.


When a model was Verilated using --prof-exec, sets the simulation runtime filename to dump to. Defaults to profile_exec.dat.


When a model was Verilated using --prof-exec, the simulation runtime will wait until $time is at this value (expressed in units of the time precision), then start the profiling warmup, then capturing. Generally this should be set to some time that is well within the normal operation of the simulation, i.e. outside of reset. If 0, the dump is disabled. Defaults to 1.


When a model was Verilated using --prof-exec, after $time reaches +verilator+prof+exec+start+<value>, Verilator will warm up the profiling for this number of eval() calls, then will capture the profiling of this number of eval() calls. Defaults to 2, which makes sense for a single-clock-domain module where it’s typical to want to capture one posedge eval() and one negedge eval().


Deprecated. Alias for +verilator+prof+exec+file+<filename>


Deprecated. Alias for +verilator+prof+exec+start+<value>


Deprecated. Alias for +verilator+prof+exec+window+<value>


When a model was Verilated using --prof-pgo, sets the profile-guided optimization data runtime filename to dump to. Defaults to profile.vlt.


When a model was Verilated using --x-initial unique, sets the simulation runtime initialization technique. 0 = Reset to zeros. 1 = Reset to all-ones. 2 = Randomize. See Unknown States.


For $random and --x-initial unique, set the simulation runtime random seed value. If zero or not specified picks a value from the system random number generator.


Disable assert checking per runtime argument. This is the same as calling VerilatedContext*->assertOn(false) in the model.


Shows the verbose version, including configuration information.


Displays program version and exits.