Superchain upgrades

The Superchain architecture is designed to implement coordinated, consensus-breaking changes—commonly known as hardforks—across all chains in the Superchain. This document provides a high-level overview of the key components and processes involved in executing these upgrades.

Superchain target

In the context of Superchain upgrades, the Superchain target (opens in a new tab) refers to a set of upgrade parameters that multiple chains in the Superchain should adhere to, enabling synchronized network upgrades. By aligning with a common Superchain target, chains can implement consensus-breaking changes simultaneously, maintaining compatibility and coherence across the Superchain ecosystem. This approach streamlines the upgrade process and reduces fragmentation within the Superchain.

ProtocolVersion L1 smart contract

The ProtocolVersion (opens in a new tab) L1 smart contract serves as an on-chain registry that records the protocol versions supported by various chains within the Superchain. It provides a standardized mechanism for chains to signal their current protocol version, facilitating coordination and compatibility checks among different chains. This contract is instrumental in managing and tracking the progression of protocol versions across the Superchain.

Superchain version signaling

Superchain version signaling (opens in a new tab) is a mechanism that allows nodes and clients to be aware of and prepare for upcoming protocol changes. This signaling is achieved through the ProtocolVersion smart contract, allowing chains to indicate their readiness for upcoming upgrades and ensuring that all participating chains are synchronized. If the node see's a versioning signal onchain before the node software has been updated for a hardfork, the node will halt to prevent chain divergence Through this signaling:

• Nodes can anticipate and implement necessary adjustments ahead of time.
• Clients are informed about the protocol version they should be compatible with, ensuring seamless interactions across the Superchain.

Activation rules

Activation rules (opens in a new tab) define the conditions under which a network upgrade or hardfork becomes active within the Superchain. These rules are based on specific timestamps, dictating when the new protocol changes take effect.

• Block Height Activation: The upgrade activates at a predetermined block number.
• Time-Based Activation: The upgrade becomes effective at a specific timestamp.

Networks that have opted into the hard fork inheritance behavior will automatically inherit the activation rules from the Superchain Registry.

rollup.halt flags on node binaries

The rollup.halt flag is an opt-in configuration option available in both the execution and consensus layer node binaries. Its primary function is to temporarily halt node activities, during the transition phase of an upgrade, if or when it encounters an incompatible or unsupported protocol version requirement.

• Execution layer configuration: In the execution layer (op-geth), the --rollup.halt flag can be set to specify the level of incompatibility (major, minor, patch, none) that will trigger a halt. This ensures that nodes do not process transactions under unsupported protocol versions.
• Consensus layer configuration: Similarly, in the consensus layer (op-node), the --rollup.halt flag serves the same purpose, allowing nodes to halt when encountering incompatible protocol versions.

Conclusion

Coordinated upgrades within the Superchain are essential for maintaining network integrity and performance. By understanding and implementing all the components mentioned in this guide, network participants can ensure smooth transitions during protocol upgrades. For comprehensive guidelines and technical specifications, refer to the Superchain upgrades spec (opens in a new tab).