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uvm_config_db set and UVM ERROR virtual if not configured

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When the UVC is instantiated only once and connected to Interface.

In top.sv

st_if st_if_0(clock, reset);

In tb_env.sv

st_pkg::st_env st0;

in build phase

st0 = st_pkg::st_env::type_id::create("st0", this);

uvm_config_db#(virtual st_if)::set(this,"*","vif",top.st_if_0);

the above code works.

Now I need to instantiate more than once, Created wrapper like this:

class if_wrapper extends uvm_component;

virtual st_if if1;

function new(string name,virtual csco_st_if if_,uvm_component parent = null);


if1 = if_;

endfunction : new

endclass : if_wrapper

in top.sv: used Gen as follows

genvar i;


for(i=0; i < `NUM; i++)

begin: c_gen

st_if st_if(clock, reset);

if_wrapper if_wr = new($psprintf("if_wrapper_%03d",i),st_if);



in tb_env.sv

st_pkg::st_env st[`NUM];

if_wrapper if_wr;

in build phase

for (int i=0; i < `NUM; i++) begin

$cast(if_wr, lookup($psprintf(".if_wrapper_%03d",i)));

uvm_config_db#(virtual st_if)::set(this,$psprintf("st%03d",i),"vif",if_wr.if1);

st = st_pkg::st_env::type_id::create($psprintf("st%03d",i),this);


Now it compiles, but I get following Error

UVM_ERROR ./sim/st/sv/st_rx_driver.sv(55) @ 0: top.tb_env.st000.st_rx_agent.driver [st_rx_driver] virtual if not configured

No Error in checking virtual interface in st_env.sv

if(!uvm_config_db#(virtual st_if)::get(this,"","vif",vif))

`uvm_error("NOVIF","virtual if not configured");


but the error appears only .st_rx_agent.driver

if(!uvm_config_db#(virtual st_if)::get(this,"","vif",vif))

`uvm_error(get_type_name(),"virtual if not configured");

How to fix this error.

Thanks in Advance


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there are a few common causes for this error

1. the if has not been set - the property "top.tb_env.st000.st_rx_agent.driver.vif" is unset (simply unset, wrong hierarchy, mistyped or similar)

2. the if has been set but the uvm_config_db parameter type is not equivalent between set() and get().

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Hi uwes,

Thanks for the reply.

Env changed only the config_db set, the get was working when uvc is instantiated only once. so mostly this will be set issue, Please let me know how I can debug this config_db in IUS or VCS simulator.

thanking you once again


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why not

1. split the full path into context plus path down from the current object

uvm_config_db#(virtual st_if)::set(this, $sformatf("*.st%03d*",i), "vif",if_wr.if1); // you have to remove "*." if st000 is a child of the current object

2. remove the postfix wildcard match

uvm_config_db#(virtual st_if)::set(this, $sformatf("*.st%03d",i), "vif",if_wr.if1);

(3.) if you are really funny you can replace the whole set with a posix regexp

uvm_config_db#(virtual st_if)::set(this, "/st[0-9]{3}/"), "vif",if_wr.if1); // would apply to direct subcomponents of "this" named "st000".. "st999" with a field "vif"

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for debugging configuration issues you can:

1. dump the database uvm_config_db#(int)::dump()

2. trace sets and gets using the +UVM_CONFIG_DB_TRACE or +UVM_RESOURCE_DB_TRACE switches in the upcoming UVM release

3. you could switch auditing on to find readers and writers of an resource uvm_resource_options::turn_on_auditing() followed by a <resource>.print_accessors()

4. you could enable the "verbose" mode of uvm_component.apply_config_settings

5. you can check using uvm_component.check_config_usage() to detect config settings write-no-read

6. you can use uvm_component.(print_config|print_config_with_audit|print_config_settings)

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Hi Owes

thanks for Debugging tricks..Point 2 (remove the postfix wildcard match) was not working, because the monitor/driver where the vif need to be set is 2 level below the uvv_env, as mentioned first email the uvc_env vif setting works .. Pluse point 3(posix regexp) gave me a syntax error.



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Hi Owes

Removed the prefix wildcard worked and Now set command is as follows

uvm_config_db#(virtual st_if)::set(this, $sformatf("st%03d*",i), "vif",if_wr.if1);

May be the vif get instant names are as follows

1. st_env (st000, or st001 ...)

2. st000.st_rx_agent.monitor , st001.st_rx_agent.monitor, ..

3. st000.st_tx_agent.monitor , st001.st_tx_agent.monitor, ..

4. st000.st_rx_agent.driver, st001.st_rx_agent.driver, ..

5. st000.st_tx_agent.driver, st000.st_tx_agent.driver, ..


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