ASIC 101 docs

Install LibreLane, OpenROAD, and the ASIC toolchain

Install the complete reproducible open-source ASIC environment. LibreLane bundles compatible versions of Yosys, OpenROAD, Magic, KLayout, Netgen, and the other tools used by the default flow.

Overview

Do not separately install random versions of every EDA tool unless you know exactly why you are doing it.

ASIC flows are sensitive to tool versions.

LibreLane provides a matched environment so:

LibreLane
Yosys
OpenROAD
Magic
KLayout
Netgen
OpenRCX
Volare

work together.

There are three common installation methods:

methodrecommendation
Nixbest/reproducible
AppImageeasiest on Linux/WSL
Dockerfallback

For the network, Nix is the default path.

AppImage is a good fallback if Nix gives you trouble.

Prerequisites

Steps

1. Windows users: install WSL2

Open PowerShell as Administrator:

wsl --install -d Ubuntu

Restart if Windows asks you to.

Then check:

wsl --list --verbose

You want Ubuntu to show:

VERSION
2

LibreLane requires WSL2, not WSL1.

Launch Ubuntu from the Start menu.

From this point onward, run Linux commands inside Ubuntu/WSL, not PowerShell.

2. Linux and WSL users: install basic tools

sudo apt-get update
sudo apt-get install -y curl git

3. Install Nix

Do not install Nix with apt.

Use the current Nix installer:

curl --proto '=https' --tlsv1.2 -fsSL \
  https://artifacts.nixos.org/nix-installer | \
  sh -s -- install --no-confirm --extra-conf "
extra-substituters = https://nix-cache.fossi-foundation.org
extra-trusted-public-keys = nix-cache.fossi-foundation.org:3+K59iFwXqKsL7BNu6Guy0v+uTlwsxYQxjspXzqLYQs=
extra-experimental-features = nix-command flakes
"

Close the terminal completely and open it again.

Why the binary cache?

Without it, Nix may build large EDA tools from source.

The cache lets you download reproducible pre-built tool binaries instead.

4. Clone LibreLane

cd ~
git clone https://github.com/librelane/librelane

Enter the repository:

cd ~/librelane

5. Enter the EDA environment

nix-shell

Your shell prompt should indicate that you are inside a Nix shell.

Every ASIC command in later pages assumes you are inside this environment.

If you leave the shell, enter it again with:

cd ~/librelane
nix-shell

6. Run the smoke test

librelane --smoke-test

The first run may also obtain the supported PDK through Volare.

The smoke test must finish successfully before continuing.

7. Confirm the important tools exist

Run:

librelane --version
yosys -V
openroad -version
klayout -v
magic --version
netgen -batch <<<'quit'

Exact version strings will change over time.

What matters is that the commands execute inside the LibreLane environment.

8. Optional fallback: AppImage

On supported Linux systems:

sudo apt-get update
sudo apt-get install -y \
  build-essential python3 python3-venv python3-pip \
  python3-tk curl make git

Download the matching LibreLane devshell AppImage from the current LibreLane release page.

Most x86-64 machines use:

librelane-devshell-x86_64.AppImage

Then:

chmod a+x ~/librelane-devshell-$(uname -m).AppImage
~/librelane-devshell-$(uname -m).AppImage

Test it:

librelane --smoke-test

Do not install both methods just because both exist. Pick one working environment.

9. Run the built-in example

Create a scratch folder:

mkdir -p ~/asic_examples
cd ~/asic_examples

Run:

librelane --run-example spm

If the example reaches the end successfully, your machine has completed a real RTL-to-GDS flow.

10. Open the example layout

Inside the folder containing the copied example configuration:

librelane --last-run --flow OpenInKLayout config.json

You should see physical chip geometry rather than RTL source code.

Results

A working installation should provide:

librelane
yosys
openroad
klayout
magic
netgen

and a working Sky130 PDK managed by Volare.

Official documentation:

Checklist

  • WSL2/Linux/macOS environment works
  • Nix or AppImage environment works
  • librelane --smoke-test passes
  • Yosys runs
  • OpenROAD runs
  • KLayout opens
  • Built-in example finishes
  • Opened an example layout
  • Continued to page 12

Questions? Ask in the network Discord.