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GOF Netlist ECO User Manual V2.0

1 Introduction

1.1 Overview
1.2 Netlist ECO Solutions
1.3 Download and Install GOF
1.4 License and Setup

1.1 Overview

GOF, Gates On the Fly, provides complete netlist solutions to accommodate various netlist ECO and debug scenarios.

1.2 Netlist ECO Solutions

Gates On the Fly implements several cutting edge ECO methodologies. Netlist ECO varies in size and complexity from case to case. Design process changes from company to company. Gates On the Fly gives users flexibility to choose one or several of the methodologies depending on the size and complexity of the changes.

The automatic functional ECO is done by a GofCall ECO script. The flow needs Implementation Netlist which is under ECO, and Reference Netlist which is re-synthesized from modified RTL with the same constraints as the pre-layout netlist. The top down API 'fix_design' is used to perform a global ECO. GOF uses the built-in Logic Equivalence Check engine to find and analyze the non-equivalent points in the top level module and its sub-modules. Logic patches are created to fix the non-equivalent modules. The final patches are optimized circuits with minimum gate count that make Implementation Netlist equal to Reference Netlist. The patches can be mapped to spare-type-gates by 'map_spare_cells' API.

When ECO changes are known and ECO size is small or the operations are repetitive like adding inverts on a bus, manual mode ECO is a better choice. Since it is more efficient and the final gates touched can be less than automatic mode ECO. Moreover, automatic and manual mode ECO can be interleaved in one GofCall ECO script.

When ECO is done in either automatic mode or manual mode, 'map_spare_cells' command is run to convert the newly added cells to spare gate types cells. Users can control only spare gate type cells being used in manual mode ECO, so that the converting stage can be bypassed.

GOF supports hierarchical ECO by set the ECO scope to the sub-modules. Some Logic Equivalence Check cases can only be resolved in flatten mode. Since GOF only focuses on the modules or spots that user specifies, it can avoid to fall into the trap of LEC failing in hierarchical netlist.

GUI mode ECO has advantage of fast ramping up. It’s good for small size ECOs. The incremental schematic feature is very helpful for analyzing the netlist before the next step is decided.

The incremental schematic is very useful in pinpointing the logic issues. GOF supports many useful APIs to fast access the database.

In section 2, eight ECO flows are listed to accommodate different ECO scenarios. In section 3, a guideline is provided for choosing the ECO flow.

1.3 Download and Install GOF

GOF release package can be found in

https://nandigits.com/download.php?gvt=0

The tool supports Linux 64bits OS. Download the release package and unzip to a directory. Set 'the_64bit_install_path/GOF64/bin' in search path.

1.4 License and Setup

Contact support@nandigits.com for evaluation license, if the evaluation netlist size is larger than 500K bytes. There are two license modes, fixed node mode and floating node mode.

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