10. Environment Setup

🧪 OpenLane2 Non-Destructive Installation Guide

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🎯 Purpose

This document describes how to install and use OpenLane2
without breaking or modifying existing OpenLane (v1) environments.

The primary goals are:

• 🔒 Environment isolation
• 🧯 Non-destructive coexistence
• ♻️ Reproducibility

OpenLane2 is treated as a separate toolchain,
not a replacement for OpenLane (v1).

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🧭 Design Principles

This project strictly follows these environment rules:

1. ❌ Do not modify existing OpenLane (v1) installations
2. ❌ Do not overwrite system-wide Python packages
3. ❌ Do not copy PDKs into this repository
4. ✅ Use Python virtual environments and external references only

Violating any of these rules risks:

• breaking existing flows, or
• reducing long-term reproducibility.

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🖥 Verified Host Environment

This setup has been verified under the following conditions:

• OS: Linux (Ubuntu 20.04 / 22.04)
• Python: 3.9 or newer
• OpenLane (v1): Optional, preserved if present
• Existing PDK installation: Required (e.g. sky130)

Typical directory layout:

$HOME/
 ├─ OpenLane/              # Existing OpenLane v1 (unchanged)
 ├─ OpenROAD/
 ├─ pdks/
 │   └─ sky130A/
 └─ openlane2-sram/        # This repository

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🐍 Python Virtual Environment (Required)

OpenLane2 must be installed inside a Python virtual environment.

▶ Create virtual environment

cd openlane2-sram
python3 -m venv venv

▶ Activate virtual environment

source venv/bin/activate

After activation, the shell prompt should look like:

(venv) user@host:~/openlane2-sram$

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📦 Install OpenLane2 (Isolated)

Important: The virtual environment must be active.

# activate venv (if not already active)
source venv/bin/activate

# upgrade pip
pip install --upgrade pip

# install OpenLane2
pip install openlane

# verify installation
openlane --version

Expected behavior

• ✅ The openlane command works inside the virtual environment
• ❌ The openlane command is not available outside the virtual environment

This confirms proper toolchain isolation and non-destructive coexistence.

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🧱 PDK Configuration

📜 Policy

• PDKs are not included in this repository
• PDKs are referenced using environment variables
• The same PDK installation may be shared between
  OpenLane (v1) and OpenLane2

🧩 Example: sky130

export PDK_ROOT=$HOME/pdks
export PDK=sky130A

Expected directory structure:

$PDK_ROOT/sky130A/

These variables can be defined in:

• ~/.bashrc, or
• a project-local setup script (recommended for reproducibility)

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🔍 Verification: Non-Destructive Coexistence

▶ Verify OpenLane2

source venv/bin/activate
openlane --version

▶ Verify existing OpenLane (v1)

cd $HOME/OpenLane
./flow.tcl -h

✅ Both tools must work independently.

If OpenLane (v1) continues to operate normally,
the setup is confirmed to be non-destructive.

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🚫 What This Setup Explicitly Avoids

This project intentionally avoids:

• Docker-based OpenLane flows
• Conda environments
• System-wide Python installations
• PATH-based OpenLane version switching

These choices keep the environment:

Simple · Explicit · Debuggable

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♻️ Reproducibility Notes

• All required commands are documented explicitly
• No implicit dependencies are assumed
• GUI tools (KLayout, Magic) are optional and external
• The environment can be recreated on a fresh machine

This ensures long-term reproducibility.

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➡ Next Step

After completing this setup, proceed to:

➡ docs/20_openlane2.md
Baseline OpenLane2 flow without SRAM macros

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Last updated: OpenLane2 environment verified and used for final GDS generation ✅