03. OpenLane2 Setup

— Isolate It Completely. Never Mix With OpenLane1 —

1. Purpose of This Chapter (Very Important)

OpenLane2 is the successor to OpenLane1.

However, in this guide:

OpenLane2 is NOT a replacement.
It is an evaluation-only environment.

The goals of this chapter are:

• Keep OpenLane1 absolutely stable
• Install OpenLane2 in complete isolation
• Prevent accidental cross-contamination
• Allow safe experimentation without risking production flow

If OpenLane1 breaks, this chapter has failed.

2. Key Differences You Must Understand

OpenLane2 differs fundamentally from OpenLane1:

• Python-based CLI (not Makefile-driven)
• Different configuration philosophy
• Faster feature evolution
• Less stability across versions

Because of this:

OpenLane2 must never be treated as a production tool (yet).

3. Absolute Isolation Rules (Non-Negotiable)

You must enforce all of the following:

• Separate directory from OpenLane1
• No shared PATH entries
• No shared aliases
• No shared virtual environments
• No shared PDK manipulation

Required Directory Layout

~/OpenLane     ← OpenLane1 (stable, production)
~/openlane2    ← OpenLane2 (evaluation only)

If you violate this, rollback is required.

4. Clone OpenLane2

4.1 Repository Clone

From WSL home:

cd ~
git clone https://github.com/efabless/openlane2.git
cd openlane2

4.2 Version Policy

• Use the cloned commit as-is
• Do not pull updates automatically
• Treat each commit as disposable

Evaluation environments are allowed to break.
Production environments are not.

5. Python Virtual Environment Setup

OpenLane2 requires Python isolation.

5.1 Create Virtual Environment

cd ~/openlane2
python3 -m venv venv
source venv/bin/activate

Your shell prompt should now indicate (venv).

5.2 Install Dependencies

pip install --upgrade pip
pip install -r requirements.txt

This may take some time.

6. Minimal Sanity Check

Do not run full flows yet.

6.1 CLI Check

openlane --help

If that fails:

python -m openlane --help

If help text appears, OpenLane2 is minimally functional.

7. Verify Non-Interference With OpenLane1

After installing OpenLane2, immediately verify:

cd ~/OpenLane
make test

Required Result

• Test still passes
• No new errors
• No Docker image changes
• No file changes inside ~/OpenLane

If this fails:

Rollback immediately using WSL import.

8. Operational Policy for OpenLane2

Correct usage:

• Feature exploration
• Macro / SRAM experiments
• Future flow evaluation
• Reading logs and behavior

Incorrect usage:

• Production tapeouts
• Benchmarking stability
• Replacing OpenLane1 results
• Copying artifacts into OpenLane1

Results from OpenLane2 are disposable.
OpenLane1 results are assets.

9. State at Completion (Pass Criteria)

At the end of this chapter:

• OpenLane1: stable and untouched
• OpenLane2: functional but isolated
• No shared state
• No ambiguity about which tool is used

This is the only safe coexistence model.

10. Next Step

Next, we handle the most valuable asset in the entire system:

➡️ 04_PDK_Setup.md

This is where rebuild cost becomes extremely high.
Proceed carefully.

Final Reminder

If you ever feel tempted to “merge” OpenLane1 and OpenLane2:

Stop. Clone. Isolate. Never mix.