In reply to saritr:
//Set with null context and "*" visible everywhere
uvm_config_db #(rx_agent_config)::set(null, "*", "db_rx_agent_config", m_rx_cfg)
//If you have delta delay/finite amount of delay before setting
//the config obj
//Wait till configuration object is modified by agent
//use null context again for module
uvm_config_db #(rx_agent_config)::wait_modified(null, "*", "db_rx_agent_config")
void'(uvm_config_db #(rx_agent_config)::get(null, "", "db_rx_agent_config", m_rx_cfg))
//Alternate way is to use small delay before getting the
//object in module initial block
initial
begin
#1;
if(!uvm_config_db #(rx_agent_config)::get(null, "", "db_rx_agent_config", m_rx_cfg))
`uvm_error("top", "rx_agent_config not found")
end