In SERIES 1, errors are driven by inserting error values into cfg_db and passing this instance of cfg_db into respective testcase.
Another method is to use nested transaction class in test class and override this nested class with original transaction class. this method provides encapsulation of error injection into that particular test. This can be understood with below discussion in verification academy forum.
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Another method is to use nested transaction class in test class and override this nested class with original transaction class. this method provides encapsulation of error injection into that particular test. This can be understood with below discussion in verification academy forum.
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There are separate sequences running on multiple instances of
UVC. In a testcase, I want to override the transaction item in
particular instance of sequence. I tried the below, which is not
working. Any clue ?
class baseseq extends uvm_sequence; task body(); basetrans = trans::type_id::create ("trans"); start_item(trans); trans.randomize(); finish_item(trans); endtask endclass class basetest extends uvm_test; task run; foreach (seq[id]) begin // Let's say id is from 0 to 4 seq[id]=baseseq::type_id::create($sformatf("seq_%0d",id), ,get_full_name()); seq[id].start(seqr[id]); end endtask endclass class mytest extends basetest; class errtrans extends basetrans; // additional functionalities endclass task run; foreach (seq[id]) begin seq[id]=baseseq::type_id::create($sformatf("seq_%0d",id), ,get_full_name()); seq[id].start(seqr[id]); end basetrans::type_id:set_inst_override(errtrans:get_type(), {get_full_name,".seq_4"}); // I expect the override type should effect from now, but is not happening !! foreach (seq[id]) begin seq[id]=baseseq::type_id::create($sformatf("seq_%0d",id), ,get_full_name()); seq[id].start(seqr[id]); end endtask endclass
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Instance overrides just require the create() name of the
instance to match the pattern of the override. You have an override that
looks like it would be intended to override the sequence, not the
transaction. It looks like you have followed most of the recommendations
in the cookbook page Sequences/Overrides - just a couple of things need changed in your code to make it work:
(1) give your transaction instance some context when you create it in class baseseq, otherwise you can't easily match it with an instance override. Recommend you change the create() to add the 3rd context argument:
The transaction (that you wish to override) now has a context which is the get_full_name() OF THE SEQUENCE.
You need to match that up with (a) your create() of the sequence and (b) your instance override.
(2) in the sequence creation and override, use the get_full_name() of seqr[4], not of the test, and append the actual transaction name to the instance override (or a wildcard):
BTW kudos for using a NESTED CLASS for your definition of errtrans,
inside your test. That is a great technique for keeping all aspects of a
testcase together in one file, especially when the override is as
simple as e.g. adding a random constraint on the base transaction. Just
remember that class still needs a `uvm_object_utils so that the factory
knows about it, and you need to ensure all such nested classes have
unique names!
(1) give your transaction instance some context when you create it in class baseseq, otherwise you can't easily match it with an instance override. Recommend you change the create() to add the 3rd context argument:
basetrans trans = basetrans::type_id::create("trans",,get_full_name()); ^^^^^^^^^^^^^^^^^
You need to match that up with (a) your create() of the sequence and (b) your instance override.
(2) in the sequence creation and override, use the get_full_name() of seqr[4], not of the test, and append the actual transaction name to the instance override (or a wildcard):
basetrans::type_id::set_inst_override(errtrans::get_type(), {seqr[4].get_full_name,".seq_4.trans"}); ^^^^^^^^ ^^^^^^ foreach (seq[id]) begin seq[id]=baseseq::type_id::create($sformatf("seq_%0d",id), ,seqr[id].get_full_name()); ^^^^^^^^^
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transaction item as given below, it is working