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9.0.1 Oct 20, 2022

#80 in #filecoin

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Used in fil_builtin_actors_state



Built-in Filecoin actors

This repo contains the code for the on-chain built-in actors that power the Filecoin network starting from network version 16.

These actors are written in Rust and are designed to operate inside the Filecoin Virtual Machine. A reference implementation of the latter exists at filecoin-project/ref-fvm.

The build process of this repo compiles every actor into Wasm bytecode and generates an aggregate bundle to be imported by all clients. The structure of this bundle is standardized. Read below for details.

This codebase is on track to be canonicalized in FIP-0031. As a result, this actor implementation will be the only one recognized by the network.

Pre-FVM actors

Actors for the following network versions are provided as well:

  • nv14 actors are provided to facilitate testing.
  • nv15 actors are provided to enable the eventual nv15=>nv16 upgrade.

Importable bundle

The main output of this repo is a CARv1 archive bundling all Wasm bytecode for all actors into a single file, with the following characteristics:

  • The CARv1 header points to a single root CID.
  • The CID resolves to a Manifest data structure that associates code CIDs with their corresponding built-in actor types.
  • The Manifest payload should be interpreted as an IPLD Map<Cid, i32>. Every entry represents a built-in actor.
  • Manifest keys (CID) point to the Wasm bytecode of an actor as a single block.
  • Manifest values (i32) identify the actor type, to be parsed as the runtime::builtins::Type enum.

Precompiled actor bundles are provided as release binaries in this repo. The fil_builtin_actors_bundle crate on crates.io will not be updated.


We usually release all actors, the runtime, and the state abstraction at the same time. That means releasing:

  • fil_actors_runtime
  • fil_actor_account
  • fil_actor_cron
  • fil_actor_init
  • fil_actor_market
  • fil_actor_miner
  • fil_actor_multisig
  • fil_actor_paych
  • fil_actor_power
  • fil_actor_reward
  • fil_actor_system
  • fil_actor_verifreg
  • fil_builtin_actors_state

We do not publish the "bundle" crate, but instead build it in CI and publish the bundle itself as a release.

To make this easier, we've added some helper scripts to the Makefile. Instructions follow.

1: Install Dependencies


  • jq (with your favorite package manager)
  • cargo-edit (with cargo install cargo-edit).

2: Bump Versions (Release)

You can bump the runtime, actors, and bundle versions with the bump-version target. See Versioning to determine the correct version bump.

make bump-version

By default, this bumps the patch version. To bump to a different version, append, e.g. BUMP=major. Valid options are:

  • patch
  • minor
  • major
  • alpha
  • beta
  • rc

You can also set a specific version with the set-version target.

make set-version VERSION=7.1.1

Commit the version changes:

git commit -a -m "Release $(make --quiet version)"

Finally, create a PR to commit your changes, make sure your PR is approved and merged before move to the next step!

3: Publish Crates

NOTE: If you're a not a member of the core FVM team, you'll need help with this step. Please make a PR at this point and ask the core team to publish a release.

Run make publish to publish all crates to crates.io. This will likely take a while as it re-builds everything from scratch for validation (multiple times).

NOTE: To do this, you'll need to:

  1. Register an account with https://crates.io and confirm your email address (if you haven't already).
  2. Login locally with cargo login.
  3. Get yourself added to the fvm-crate-owners team.

4: Bump Versions (Alpha)

Finally, bump the versions to the next alpha and commit the changes:

make bump-version BUMP=alpha
git commit -a -m "Release $(make --quiet version)"

Instructions for client implementations

Obtaining an actors bundle

There are two options:

  1. Building from source.
  2. Downloading the precompiled release bundle from GitHub.

Instructions to build from source (option 1):

  1. Clone the repo.
  2. Check out the relevant branch or tag (see Versioning section below).
  3. make bundle from the workspace root.

The bundle be written to output/builtin-actors.car.

Both options are compatible with automation via scripts or CI pipelines.

Integrating an actors bundle

This part is implementation-specific. Options include:

  1. Embedding the bundle's CARv1 bytes into the distribution's binary.
  2. Downloading CARv1 files on start (with some form of checksumming for added security).

Loading and using the actors bundle with ref-fvm

Once the implementation has validated the authenticity of the bundle, it is expected to do the following:

  1. Import the CARv1 into the blockstore.
  2. Retain the root CID in memory, indexed by network version.
  3. Feed the root CID to ref-fvm's Machine constructor, to tell ref-fvm which CodeCID maps to which built-in actor.

Multiple network version support

Because every network version may be backed by different actor code, implementations should be ready to load multiple actor bundles and index them by network version.

When instantiating the ref-fvm Machine, both the network version and the corresponding Manifest root CID must be passed.


A fair question is how crate versioning relates to the protocol concept of ActorVersion. We adopt a policy similar to specs-actors:

  • Major number in crate version correlates with ActorVersion.
  • We generally don't use minor versions; these are always set to 0.
  • We strive for round major crate versions to denote the definitive release for a given network upgrade. However, due to the inability to predict certain aspects of software engineering, this is not a hard rule and further releases may be made by bumping the patch number.

Development versions will use qualifiers such as -rc (release candidate).

As an example of application of this policy to a v10 actor version lineage:

  • Unstable development versions are referenced by commit hash.
  • Stable development versions are tagged as release candidates: 10.0.0-rc1, 10.0.0-rc2, etc.
  • Definitive release: 10.0.0.
  • Patched definitive release: 10.0.1.
  • Patched definitive release: 10.0.2.
  • Network upgrade goes live with 10.0.2.

About this codebase

Relation to specs-actors

This repo supersedes specs-actors, and fulfils two roles:

  • executable specification of built-in actors.
  • canonical, portable implementation of built-in actors.


This codebase was originally forked from the actors v6 implementation of the Forest client, and was adapted to the FVM environment.


Because this codebase is a common good across all Filecoin client implementations, it serves as a convergence area for all Core Devs regardless of the implementation or project they identify with.


Dual-licensed: MIT, Apache Software License v2, by way of the Permissive License Stack.

Except the EVM precompile test data, which is licensed under the LGPL v3 and not included in crates or build artifacts.


~201K SLoC