> ## Documentation Index
> Fetch the complete documentation index at: https://optimism-373f39ad-soyboy-docs-deploy-a-contract.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Generating absolute prestate and preimage files

> Generate, verify, and configure the kona-client absolute prestate for permissionless fault proofs.

# Overview

The absolute prestate is the on-chain commitment to a specific build of `kona-client`. The matching preimage (a gzipped binary) is what `op-challenger` runs at dispute time. This guide is the minimal reproducer.

<Info>
  As of [Upgrade 19](/notices/upgrade-19), `CANNON_KONA` (game type `8`) is the respected game type for permissionless fault proofs. If your chain is not yet in the public Superchain Registry, follow [Generating a custom kona-client absolute prestate](/chain-operators/tutorials/kona-custom-prestate) instead.
</Info>

## Prerequisites

* [Docker](https://docs.docker.com/engine/install/) running
* [`just`](https://github.com/casey/just) installed

## Generate and verify the prestate

<Steps>
  <Step title="Check out the release tag">
    ```bash theme={null}
    git clone https://github.com/ethereum-optimism/optimism.git
    cd optimism
    git checkout kona-node/v<VERSION>
    ```
  </Step>

  <Step title="Build the prestate">
    ```bash theme={null}
    just reproducible-prestate-kona
    ```

    The build runs in Docker and writes artifacts to `rust/kona/prestate-artifacts-cannon/`.
  </Step>

  <Step title="Read and verify the hash">
    ```bash theme={null}
    jq -r .pre rust/kona/prestate-artifacts-cannon/prestate-proof.json
    ```

    Match the printed hash against the `cannon64-kona` entry for your release tag in [`standard-prestates.toml`](https://github.com/ethereum-optimism/superchain-registry/blob/main/validation/standard/standard-prestates.toml). A match confirms your build environment is honest.
  </Step>
</Steps>

## Configure op-challenger

Upload the hash-named file `rust/kona/prestate-artifacts-cannon/0x<HASH>.bin.gz` (produced by the build) to a location reachable by your `op-challenger` instances, then add the kona-specific env vars to your existing challenger config:

```bash theme={null}
OP_CHALLENGER_TRACE_TYPE=cannon-kona,permissioned
OP_CHALLENGER_CANNON_KONA_PRESTATES_URL=<HTTP_URL_PATH_TO_PRESTATES>
```

The challenger appends `/0x<hash>.bin.gz` to `*_PRESTATES_URL` to resolve the right binary per dispute. Your existing `OP_CHALLENGER_ROLLUP_CONFIG`, `OP_CHALLENGER_L2_GENESIS`, and `OP_CHALLENGER_GAME_FACTORY_ADDRESS` continue to apply unchanged.

## Next Steps

* [Generating a custom kona-client absolute prestate](/chain-operators/tutorials/kona-custom-prestate) — for chains not yet in the Superchain Registry.
* [Migrating to permissionless fault proofs](/chain-operators/tutorials/migrating-permissionless).
* [Fault proofs explainer](/op-stack/fault-proofs/explainer).