Why does Nios® V processor system simulation fail with no print-out message and multiple “x” values along the processor’s signals?

This problem may be seen in the Synopsys* VCS* and VCS* MX simulators when simulating the Nios® V processor system generated from

• Intel® Quartus® Prime Pro Edition Software version 23.1 to 23.4, or  

• Intel® Quartus® Prime Standard Edition Software version 23.1std  

This is due to the X-propagation support in the simulators.

To workaround this problem, follow these steps:

Switch off the X-propagation feature on the processor core, 

1. Generate testbench system from the Platform Designer. 

2. Navigate into the Synopsys* simulator directory.

   • $ cd <Project>/sys_tb/sys_tb/sim/synopsys 

3. Append -xprop=xpropconfig into the shell script in the vcs or vcsmx folder. 

For example: 

• USER_DEFINED_ELAB_OPTIONS=”-xprop=xpropconfig” 

4. Create a file named xpropconfig in the vcs or vcsmx folder (beside the shell script). 

5. Copy the following text into xpropconfig, and change the processor entity name. 

tree {<Nios V processor HDL entity name>} {xpropOff}; 

6. Run the simulator. 

This problem is currently scheduled to be resolved in Intel® Quartus® Prime Pro Edition Software version 24.1 and later.