Is there some wrong with the uvm_config_db#::get method?

[hugemx830202]

Hi,

I want to get an object (which is created in TB env level) in Test case level, but found assert failed error, seems that uvm_config_db#::get method can not obtain the desired object in TB env, could you help me to point out why? Thanks.

The followings are parts of my codes, item 1 : defined my test_obj, item 2 : created the test_obj in TB env level, item 3: want to obtain the created object in test case level, but failed

1. Define the test_obj class:

class test_obj extends uvm_object;

rand bit test;

`uvm_object_utils(test_obj)

function new(string name="test_obj");

super.new(name);

test = 0;

endfunction

endclass : test_obj

2. in TB env level:

class tb_axi_ovc_self_loop extends uvm_component;

test_obj env_obj; // the object that I want to override

`uvm_component_utils_begin(tb_axi_ovc_self_loop)

`uvm_field_object (env_obj, UVM_ALL_ON)

`uvm_component_utils_end

function new();

env_obj = new("test_obj");

endfunction : new

function void build_phase(uvm_phase phase);

super.build_phase(phase);

endfunction : build_phase

endclass

3.in Test Case level

class test_axi_ovc extends uvm_test;

tb_axi_ovc_self_loop tb_axi_ovc_self_loop_inst;

string seq_name_s;

test_obj tc_obj;

`uvm_component_utils(test_axi_ovc)

function new(string name="test_axi_ovc", uvm_component parent);

super.new(name, parent);

endfunction: new

function void build_phase(uvm_phase phase);

super.build_phase(phase);

tb_axi_ovc_self_loop_inst = tb_axi_ovc_self_loop::type_id::create("tb_axi_ovc_self_loop_inst", this);

endfunction : build_phase

function void connect_phase(uvm_phase phase);

super.connect_phase(phase);

//get the test object

assert(uvm_config_db#(test_obj)::get(this, "tb_axi_ovc_self_loop_inst","env_obj", tc_obj));

//modify the object if needed

tc_obj.test = 1; //but found assert failed here, please help me to point out the reason, thanks.

endfunction : connect_phase

endclass

Edited March 28, 2011 by hugemx830202

[uwes]

hi,

it appears that you are mixing field automation and uvm_config_db. if you do use the field macros you have to use uvm_config_db#(uvm_object)::set+get.

this is a common pitfall with the new config_db: the type arg has to be the same! when doing the get() and the set(). (so even base type + derived type doesnt work). this becomes a problem specifically when the field automation is used with the config_db - because the type parameter used to store is not widely known (its documented but ...

the ref says:

  
 //| get_config_int(...) => uvm_config_db#(uvm_bitstream_t)::get(cntxt,...)
 //| get_config_string(...) => uvm_config_db#(string)::get(cntxt,...)
 //| get_config_object(...) => uvm_config_db#(uvm_object)::get(cntxt,...)

so for integral types(enums,ints,...) use uvm_bitstream_t, for strings use string and for objects use uvm_object ...