How to Disable Printing in UVM Utility Macros for a Single Field
The UVM framework offers a comprehensive set of utility macros that simplify testbench development and debugging. Among these are powerful printing macros like uvm_info, uvm_warning, uvm_error, etc., which help in logging messages during test execution. However, sometimes you might need to selectively disable printing for specific fields within your testbench, without affecting the overall logging behavior. This article will guide you on how to achieve this effectively.
Understanding the Problem
The UVM printing macros are designed to provide a global mechanism for logging messages. This global nature can sometimes lead to excessive logging, particularly when you're debugging a specific aspect of your testbench. You might find yourself overwhelmed by a deluge of printed messages, making it difficult to pinpoint the relevant information. This is where the ability to disable printing for specific fields becomes crucial.
Common Scenarios for Disabling Printing
Several scenarios might necessitate selectively disabling printing:
- Debugging Complex Scenarios: When focusing on a specific part of your testbench, you might want to suppress the printing of unrelated fields to avoid clutter and enhance clarity.
- Performance Optimization: Printing can impact the overall performance of your simulation. Disabling printing for non-critical fields can improve simulation speed, especially during long runs.
- Large Data Structures: Printing large data structures like arrays or complex objects can consume significant time and memory. In such cases, disabling printing for these structures can optimize resource usage.
Methods to Disable Printing for a Single Field
Here are the two primary approaches for disabling printing for a single field:
1. Conditional Printing:
This method involves using conditional statements within your uvm_info, uvm_warning, uvm_error, etc. macros to control the printing based on the field's value. This allows you to selectively enable or disable printing based on the specific conditions within your testbench.
Example:
class my_class extends uvm_object;
rand int field_a;
rand int field_b;
function void print_fields;
if (field_a != 0) begin
uvm_info("MY_CLASS", $sformatf("Field A: %0d", field_a), UVM_LOW);
end
if (field_b != 0) begin
uvm_info("MY_CLASS", $sformatf("Field B: %0d", field_b), UVM_LOW);
end
endfunction
endclass
In this example, field_a is printed only if it's non-zero. This approach provides a fine-grained control over printing based on specific conditions within your testbench.
2. Modifying the UVM Logging Verbosity:
The UVM logging system allows you to configure the verbosity level for different categories. By manipulating the verbosity level, you can selectively disable printing for certain fields without affecting the overall logging behavior.
Example:
class my_class extends uvm_object;
rand int field_a;
rand int field_b;
function void print_fields;
uvm_info("MY_CLASS", $sformatf("Field A: %0d", field_a), UVM_LOW);
uvm_info("MY_CLASS", $sformatf("Field B: %0d", field_b), UVM_LOW);
endfunction
endclass
initial begin
uvm_config_db#(uvm_verbosity)::set(this, "MY_CLASS", "field_b", UVM_NONE);
end
Here, the uvm_config_db is used to set the verbosity level for field_b to UVM_NONE. This will effectively disable printing for field_b without impacting the printing of field_a.
Key Points to Remember
- Verbosity Levels: The UVM logging system uses verbosity levels (e.g.,
UVM_NONE,UVM_LOW,UVM_MEDIUM,UVM_HIGH,UVM_FULL) to control the amount of logging. - Category-Specific Control: You can apply verbosity settings to specific categories (e.g.,
MY_CLASS) for targeted control over printing. - Hierarchical Settings: Verbosity settings can be defined hierarchically within your testbench, allowing you to override settings at lower levels.
Conclusion
Disabling printing for specific fields in UVM utility macros is a valuable technique for managing the output of your testbench. By understanding the different methods and considering the appropriate scenario, you can fine-tune your logging behavior to streamline debugging, improve performance, and effectively manage resource consumption. Choosing the right approach depends on your specific requirements and the level of granularity needed for controlling printing within your testbench.