Cold Start

Concept

In the context of tandem simulation that pairs an Instruction-Level Abstraction (ILA) with an RTL Execution Model (RTEM), a 'cold start' is the initialization procedure used to bring RTL micro-architectural variables (e.g., internal counters, pipeline registers) that are not represented in the ILA to a known reset state, so that architectural-variable values lifted from the ILA can be safely substituted into the RTL model before co-simulation begins.

First seen 6/6/2026

Last seen 6/6/2026

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Cold Start

In generalized tandem simulation, an abstract Instruction-Level Abstraction (ILA) model is co-simulated against a more detailed RTL Execution Model (RTEM) of the same design. Because the ILA deliberately omits many RTL micro-architectural state elements (internal counters, pipeline registers, and similar implementation details), those RTL variables have no counterpart in the ILA and must be initialized before the two models can be brought into lock-step.

Purpose

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Tandem Simulation ← uses 93% 1e

Tandem simulation uses cold start to initialize micro-architectural variables

Jump-Starting (Warm-Up Simulation) ← uses 90% 1e

Jump-starting uses cold start to initialize micro-architectural variables

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Jump-Starting (Warm-Up Simulation) USES Extracted graph relationship

CITATIONS

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[1] Cold start sets RTL micro-architectural variables (internal counters, pipeline registers) that are not present in the ILA to their reset values, analogous to the approach used in processor tandem simulation. Generalizing Tandem Simulation: Connecting High-level and RTL Simulation Models

[2] The cold start is automated via an additional 'cold start' field of the refinement map, which contains a pre-swap cycle/sequence section (input stimulus to the RTEM, e.g., asserting reset for a couple of cycles or a general reset-and-global-start sequence) and a swap cycle that holds swapped RTAVs long enough for multi-cycle propagation into micro-architectural variables. Generalizing Tandem Simulation: Connecting High-level and RTL Simulation Models

[3] After the cold start, the AV map is used to set the RTAVs with the corresponding ILAVs from the ILA model, enabling coherent co-simulation between the ILEM and the RTEM. Generalizing Tandem Simulation: Connecting High-level and RTL Simulation Models