UVM basics -------- uvm_root

Uvm_root is the top-level instance of UVM that plays the role of a top-level and Phase Controller for component. This class does not need to be instantiated by the user. It is an automatically instantiated class that the user calls directly through uvm_top. Any component, as long as its parent is not specified, will act as a child of the top. Top manages all component phase; 1. the UVM automatically creates a single instance of uvm_root that users can access via the Global (uvm_pkg-scope) variable, uvm_top.2. key roles of uvm_top instances: 1. implicit top-level (implicit top level) The uvm_top serves as an implicit top-level component. any component whose parent is specified as null becomes a child of uvm_top. thus, all UVM components in simulation are descendants of uvm_top . If all created parents are specified as null, they will become the child of uvm_top, and uvm_top is the top layer of the UVM build tree.
2. phase Control uvm_top manages the phasing for all components. 3. search use uvm_top to search for components based on their hierarchical name. see find and find_all. (use the uvm_top hierarchical name-based search component) 4. report configuration use uvm_top to globally configure report verbosity, log files, and actions. for example, uvm_top.set_report_verbosity_level_hier (uvm_full) wocould set full verbosity for all components in simulation. 5. global Reporter because uvm_top is globally accessible (in uvm_pkg scope), UVM's reporting mechanism is accessible from anywhere outside uvm_component, such as in modules and sequences. see uvm_report_error, uvm_report_warning, and other global methods.
1. Attribute uvm_component top_levels [$]; // each top is registered in I. e test, it includes des Uvm_test_topComponent that is created by run_test as well as any other top level components that have been instantiated anywhere in the hierarchy. bit enable_print_topology = 0; // If set, print the topological structure bit finish_on_completion = 1 at the end of end_of_elaboration phase; // If set, then run_test will call $ finish after all phases are executed. time phase_timeout = 'uvm _ default_timeout; static local uvm_root m_inst; bit m_phase_all_done; // all stages are completed
2. main API methods: 1. virtual task run_test (string test_name = ""): // parses the command line "+ uvm_testname =", extracts uvm_test_top from the factory, constructs an instance, and calls the corresponding instance.
1. phases all components through all registered Phases 2. if the optional test_name argument is provided, or if a command-line plusarg, + uvm_testname = test_name, is found, then the specified component is created just prior to phasing. 2. find/find_all: 1. function void uvm_root: find_all (string comp_match, ref uvm_component comps [$], input uvm_component comp = NULL); // query the entire uvm_top and call m_find_all_recurse to implement 2. function uvm_component uvm_root: Find (string comp_match); // call uvm_root: find_all to implement 3. uvm_root private function:

1. function uvm_root: New (); // set reporter, command_processor, and call report_header 1. call super. new ("_ top _", null) sets uvm_root to the top layer of the tree 2. set reporter, get command_processor, and call report_header 3. call m_check_verbosity to obtain and set verbosity 2 through the command line. function uvm_root: Get (); 1. form a single-State class of uvm_root 2. uvm_domain: get_common_domain (); m_inst.m_domain = uvm_domain: get_uvm_domain () is called to generate two domains, one common and one uvm_domain 3. task uvm_root: run_phase (uvm_phase phase); // This function mainly checks whether $ time is 0. If not 0, an error is reported because run must start from 0. function void uvm_root: m_do_dump_args (); // If the command line has + uvm_dump_linline_args, output all the parameters of the command line 5. function void uvm_root: build_phase (uvm_phase phase); // call some built-in functions to complete the UVM simulation environment configuration: Super. build_phase (phase); m_set_cl_msg_args (); m_do_verbosity_settings (); // parse command line Input + uvm_set_verbosity =, mainly for some syntax checks. If any problem is found, an error is reported, do not process the settings m_do_timeout_settings (); // parse the "+ uvm_timeout =" command line, and apply the settings to uvm_top m_do_factory_settings (); // parse the + (parser | parser) = of the command line, call m_process_inst_override or call m_process_type_override m_do_config_settings (); obtain from the command line + (uvm_set_config_int | uvm_set_config_int) = settings, parse the settings and call m_process_config to record these settings in the resource database m_do_max_quit_settings (); + uvm_max_quit_count = this option for parsing the command line, set this option to the global report_server m_do_dump_args (); // If the command line has + uvm_dump_linline_args, all parameters of the command line are output.



From Weizhi note (wiz)