(extended) test configuring environment

UVM
1

I have a test_base, and several test extensions. In the extensions, I would like to change some agents from active->passive. However I’m not sure how to do this in the correct order… see the following code comments:

class test_UDP_LL extends test_base;

  virtual function void build_phase(uvm_phase phase);
    // cfg.init(...); // I cannot do this because cfg hasnt been created yet.
    super.build_phase(phase); // execute test base
    // cfg.init(...); // I cannot do this because... it's too late.  The test base already built the environment.
  endfunction

//...

endclass

What is the standard approach here? Create local variables in the test_base, and set those before super.build, or perhaps create the env cfg object in the test_base new?

2

In reply to bmorris:

I do nor know why you want to run the init task of your configuration. One objective of a test is to customize yurr verification environment, i.e. setting your agents UVM_ACTIVE or UVM_PASSIVE.

What I normally do is the following:
//-----------------------------------------------------------------------------
class example_top_test1 extends example_top_base_test;
//-----------------------------------------------------------------------------

`uvm_component_utils(example_top_test1)
//---------------------------------------------------------------------------
// methods
//---------------------------------------------------------------------------

extern function new(string name = “example_top_test1”, uvm_component parent = null);
extern virtual function void build_phase(uvm_phase phase);
extern task run_phase(uvm_phase phase);
//---------------------------------------------------------------------------
// constraints
//---------------------------------------------------------------------------

endclass : example_top_test1
//---------------------------------------------------------------------------

function void example_top_test1::build_phase(uvm_phase phase);
// Include your settings
uvm_config_db#(int)::set(this, “env.apb_env_i.agent”, “is_active”, UVM_ACTIVE);
uvm_config_db#(int)::set(this, “env.spi_env_i.agent”, “is_active”, UVM_ACTIVE);
// NEED to set configurations before calling super.build_phase() which creates the
// verification hierarchy.
super.build_phase(phase);
endfunction : build_phase
In the corresponding agents I’m calling uvm_config_db-get.
This works fine.
Hope this helps.

Christoph

3

In reply to bmorris:

Since it’s your code, you can define a hook method:


class test_UDP_LL extends test_base;

  virtual function void build_phase(uvm_phase phase);
    // cfg.init(...); // I cannot do this because cfg hasnt been created yet.
    
    pre_build();

    super.build_phase(phase); // execute test base
    // cfg.init(...); // I cannot do this because... it's too late.  The test base already built the environment.
  endfunction


  virtual function void pre_build();
    // empty ...
    // ... or pure virtual if class is abstract
  endfunction

//...

endclass

Another thing I like to do is to call randomize() on config stuff even when you know the exact values you want. This way you can always add constraints in sub-classes and use factory overrides to switch them.


class your_config;
  function void init():
    randomize() with {
      soft some_agent_cfg.is_active == UVM_ACTIVE;
    }
  endfunction
endclass


class your_passive_config extends your_config;
  constraint agent_passive {
    some_agent_cfg.is_active == UVM_PASSIVE;
  }
endclass


your_config::set_type_override(your_passive_config::get_type());