uvm_config_db应用示例

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本篇举2个例子说明一下uvm中config_db的使用：如下图所示

  1. case 1

我们把第一个参数设置为null， 并且instance_name设置为uvm_test_top, 这就意味着test_case中所有的component都可以访问要设置的item：

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class base_env extends uvm_env;
  ...
  string name;
 
  virtual function void build_phase (uvm_phase phase);
    super.build_name ();
 
    // Retrieve the string that was set in config_db from the test class
    if (uvm_config_db #(string) :: get (null, "uvm_test_top", "Friend", name))
      `uvm_info ("ENV", $sformatf ("Found %s", name), UVM_MEDIUM)
 
  endfunction
endclass
 
class base_test extends uvm_test;
  ...
  base_env   m_env;
 
  virtual function void build_phase (uvm_phase phase);
    ...
 
    // Set this string into config_db
    uvm_config_db #(string) :: set (null, "uvm_test_top", "Friend", "Joey");
  endfunction
endclass

我们在仿真时可以在命令行中加入命令+VUM_CONFIG_DB_TRACE来通过打印信息检查环境是否OK， 上面的例子仿真的log如下所示：

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ncsim> run
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_root.svh(392) @ 0: reporter [UVM/RELNOTES] 
----------------------------------------------------------------
UVM-1.2
(C) 2007-2014 Mentor Graphics Corporation
(C) 2007-2014 Cadence Design Systems, Inc.
(C) 2006-2014 Synopsys, Inc.
(C) 2011-2013 Cypress Semiconductor Corp.
(C) 2013-2014 NVIDIA Corporation
----------------------------------------------------------------
UVM_INFO @ 0: reporter [RNTST] Running test base_test...
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.base_env.recording_detail' (type logic signed[4095:0]) read by uvm_test_top.base_env = null (failed lookup)
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.base_env.recording_detail' (type int) read by uvm_test_top.base_env = null (failed lookup)
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/SET] Configuration 'uvm_test_top.Friend' (type string) set by  = (string) "Joey"
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.base_env.m_agent0.recording_detail' (type logic signed[4095:0]) read by uvm_test_top.base_env.m_agent0 = null (failed lookup)
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.base_env.m_agent0.recording_detail' (type int) read by uvm_test_top.base_env.m_agent0 = null (failed lookup)
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.base_env.m_agent1.recording_detail' (type logic signed[4095:0]) read by uvm_test_top.base_env.m_agent1 = null (failed lookup)
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.base_env.m_agent1.recording_detail' (type int) read by uvm_test_top.base_env.m_agent1 = null (failed lookup)
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.Friend' (type string) read by  = (string) "Joey"
UVM_INFO testbench.sv(36) @ 0: uvm_test_top.base_env [ENV] Found Joey
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_report_server.svh(847) @ 0: reporter [UVM/REPORT/SERVER] 
--- UVM Report Summary ---

** Report counts by severity
  1. case 2

设置第一个参数为this， instance_name 为空， 如下：

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uvm_config_db #(string) :: set (this, "", "Friend", "Joey");
 
// Same get method
if (uvm_config_db #(string) :: get (null, "uvm_test_top", "Friend", name))
    `uvm_info ("ENV", $sformatf ("Found %s", name), UVM_MEDIUM)

log如下， 仍然可以正确获取参数：

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UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/SET] Configuration 'uvm_test_top.Friend' (type string) set by uvm_test_top = (string) "Joey"
...
UVM_INFO /playground_lib/uvm-1.2/src/base/uvm_resource_db.svh(121) @ 0: reporter [CFGDB/GET] Configuration 'uvm_test_top.Friend' (type string) read by  = (string) "Joey"