Is it valid to pass uvm_component parameter while creating instance of a sequence?

UVM
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1

Hi,

In our code base, when creating an instance of a sequence inside an environment, we pass two parameters to create() which are string name and parent. But I don’t understand the reasoning behind it and also UVM doesn’t complain about it.

Here is an example code:

class test_magic_seq_c extends uvm_sequence#(magic_word);

class magic_env_c extends uvm_env;

test_magic_seq_c   test_magic_seq;
test_magic_seq = test_magic_seq_c::type_id::create("test_magic_seq",  this);

endclass: magic_env

I would appreciate if someone can provide me a reason how this is valid as sequence is uvm_object.

Thanks in advance.

2

The name gets used for reporting and debugging. If this sequence creates sub-sequences, it creates a pathname similar to call stack.

The parent get used as a context for controlling factory overrides.

3

Could you please elaborate on this as generally ‘parent’ is passed for uvm_component and not for uvm_object. Also, as sequence class gets extended from uvm_object, why do we pass parent when creating a sequence. (constructor of uvm_object/uvm_sequence class also has a single parameter of ‘name’)

function new (	string 	name	 = 	"uvm_sequence"	)

Is it that if we don’t pass parent parameter, it’s not possible to instance override?

Appreciate your response!

4

Correct. You will only be able to factory override the sequence by type.

5

Thanks Dave!

6

Hi Dave ,

Isn’t this partially true ?
As we discussed in thread the 3rd argument ‘contxt’ to create function also enables instance override for both uvm_object and uvm_components irrespective of whether an actual was passed to 2nd argument ‘parent’ of type uvm_component.
From what I am able to recollect from all examples that I have tried in the past,
if all 3 arguments are passed to create , the ‘contxt’ argument takes precedence over ‘parent’ and the instance override should be set using the ‘contxt’ argument.
I found a blog which has examples of instance override using ‘contxt’ argument and without passing an actual to parent argument.

7

Yes, I forgot about the third argument. The context is ultimately just a string name.