Verilog Checks on Initialization

Initializing registers at the point of declaration may be tricky. If your (System)Verilog code is not going to be synthesized (e.g. testbench), it is completely acceptable. FPGA synthesis tools may also take initialization into account, so depending on your FPGA project, initializing registers when they are declared in the code may be a viable (or even preferred) option.

ASIC synthesis tools however will ignore initialization as in the first example, which may lead to a mismatch between synthesis and simulation. In such a case, initialization should be done using resets, as in the second example.

By default, Sigasi Visual HDL warns for register initialization at the point of the declaration. For FPGA projects it may be desirable to turn the warning off, whereas for ASIC projects one may want to raise the severity to error.

module fpga_only(input clk, input rst, input ii, output logic oo = 1'b0);
    logic sig = 1'b0;

    // ...
endmodule

module asic_fpga(input clk, input rst, input ii, output logic oo);
    logic sig;

    always @(posedge clk) begin
        if (rst == 1) begin
            sig = 1'b0;
            oo  = 1'b0;
        end
        else begin
            // ...
        end
    end
endmodule

Rule configuration

This rule can be disabled for your project, or its severity and parameters can be modified in the project linting settings. Alternatively, it can be manually configured with the following template:

35/severity/${path}={error|warning|info|ignore}