Problem with set_inst_override_by_type

UVM
1

here is a part of my code ,da is the integer variable in the class sequence_item which not shown


class packer_sequence extends uvm_sequence #(packet);
packet packet_item;
task body
  packet_item = packet::type_id::create("packet");
  start_item(packet_item);
  packet_item.randomize();
  finish_item(packet_item);
endtask  
endclass 

class test_da_is_10 extends test_base 
  virtual function void build_phase(uvm_phase phase )
     super.build_phase(phase);
     set_inst_override_by_type("env.sgt.sqr.packer_sequence.packet_item",packet::get_type(),packet_da_10::get_type());
endclass

the problem is that the value of da is not 10 even if i useset_inst_override_by_type(“env.sgt.sqr.packer_sequence.req”,packet::get_type(),packet_da_10::get_type());

if i change the code to this


class packer_sequence extends uvm_sequence #(packet);
task body
`uvm_do(req);
endtask  
endclass
class test_da_is_10 extends test_base
  virtual function void build_phase(uvm_phase phase )
     super.build_phase(phase);
     set_inst_override_by_type("env.sgt.sqr.packer_sequence.req",packet::get_type(),packet_da_10::get_type());
endclass

the problem was fixed, the value of da is 10 now. why the problem fixed? how can the value of da be changed to 10 without using uvm_do?

2

In reply to peter:

Two issues with your code. There is no need to create a separate packet_item variable; there is already a req variable. You named your sequence_item “packet”, but you overrode “packet_item”.

Change your code to

class packer_sequence extends uvm_sequence #(packet);
task body
  req = packet::type_id::create("req");
  start_item(req);
  req.randomize();
  finish_item(req);
endtask  
endclass 
 
class test_da_is_10 extends test_base 
  virtual function void build_phase(uvm_phase phase )
     super.build_phase(phase);
     set_inst_override_by_type("env.sgt.sqr.packer_sequence.req",packet::get_type(),packet_da_10::get_type());
endclass
3

In reply to dave_59:

thanks for reply, i changed the code as you posted , but the value of da is still not 10.
i know there is no need to create new var, but i am confused about that
req holds the transaction object, if i declare a new var called packet_item, and i wrote this code

packet_item = packet::type_id::create("packet").

packet_item should hold the object too.
what is the issues with below code? Please correct me if my concept is wrong.

 set_inst_override_by_type("env.sgt.sqr.packer_sequence.packet_item",packet::get_type(),packet_da_10::get_type());

By the way, how to print warning message if set_inst_override_by_type not work sucessfully?Thanks a lot!!

4

In reply to peter:

Could you please follow the coding guidelines and change your code to this:

packet_item = packet::type_id::create("packet_item")

.

set_inst_override_by_type is defined for uvm_components and factory. You are handling your object liek a component. But you can perform the command also on the factory like this:

factory.set_inst_override_by_type({get_full_name(),".",
                                   relative_inst_path},
                                   original_type,
                                   override_type);
5

In reply to chr_sue:

It’s more than just a “guideline”. The UVM only knows about the string names you give objects. It knows nothing of the variable identifier names. As I stated in my first reply, you named your sequence_item “packet”, but you overrode “packet_item”.

6

In reply to dave_59:

I am so sorry, there is a only typo in my top post.
it should be

packet_item = packet::type_id::create("packet_item")

. My class file does not have this typo

But even using

packet_item = packet::type_id::create("packet_item")

, the value of da is not 10
.I am still finding the reason.
could you tell me how to print warning message if set_inst_override_by_type not work sucessfully?
i think there is a problem about the path (env.sgt.sqr.packer_sequence.packet_item), so set_inst_override_by_type not work

7

In reply to peter:

Hi Peter, what’s the root cause of this problem ?
How did it work out ?
Thx