Interview prompt

Global seed vs per-agent vif — which API?

WHITEBOARD CHAIN

1. DECLARE    interfaces / types / ports you need
2. SKELETON   class extends + utils macro + key methods
3. MECHANISM  fill one critical method while narrating
4. PITFALL    name one bug juniors make on this pattern
5. TEST       how you would smoke-test the component

• vif: config_db scoped to hierarchy path — set in top, get in agent

• global seed: uvm_resource_db or plusarg — not tied to one component path

• config_db dump for bring-up; resource pool for cross-test globals

Reference sketch (≤40 lines)

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// hierarchical vif
uvm_config_db#(apb_vif)::set(this, "env.agent*", "vif", vif);
// global seed
uvm_resource_db#(int)::set("GLOBAL_SEED", seed, this);

Mechanism to narrate

• config_db: scoped by instance path — best for vif, cfg objects

• resource_db: global name lookup — seeds, shared knobs

• Wildcard set("*") works but hides path bugs — use sparingly

Smoke test (5 minutes)

• Explain which API for vif vs seed in 30 seconds.

• Describe uvm_config_db::dump() use after build_phase.

Common pitfalls

• Wildcard set for everything.

• Same field name collision across agents.

• get in wrong phase.