Decoupled SVM

Decoupled SVM refers to the separation of the Solana Virtual Machine (SVM) from Solana's native consensus layer, turning the SVM into an independent execution layer.

The Decoupled SVM is one of the core innovations of SOON. By decoupling the SVM from Solana's original consensus mechanisms, the execution layer becomes modular, allowing it to be deployed across various ecosystems while addressing the unique challenges of rollup architectures.

Core Components and Decoupling Process

To fully appreciate the Decoupled SVM's architecture, it's important to first understand the core components of a traditional Solana validator and how they have been restructured to fit the needs of a rollup.

1. SigVerifyStage: This stage is responsible for verifying the cryptographic signatures of incoming transactions. It ensures that only transactions signed by valid keys are processed, maintaining the integrity and security of the network.

2. BankingStage: The BankingStage is where transactions are processed. It applies the transactions to the current state, updating account balances, executing smart contracts, and recording the results. In a traditional Solana environment, this stage works closely with Solana’s consensus mechanisms to ensure that transactions are ordered and executed correctly.

3. SVM Executor: The SVM Executor is the core component responsible for interpreting and executing instructions within transactions. It processes smart contract code, updating the state based on the logic defined in these contracts. This executor is highly optimized for performance, leveraging Solana’s parallel processing capabilities to handle a high throughput of transactions.

4. Entry: The Entry component is responsible for ordering transactions before they are packaged into blocks. In Solana, this involves integrating with the Proof of History (PoH) mechanism to timestamp transactions and ensure they are processed in the correct sequence.

In the Decoupled SVM, these components are reconfigured to operate independently of Solana's original consensus processes. The key change is the removal of the Tower BFT consensus layer and the Proof of History service, which are unnecessary in a rollup context. Instead, the Decoupled SVM relies on the L1 for consensus and security, focusing purely on transaction execution and state updates.

The decoupling process involves retaining only the essential execution-related components—SigVerifyStage, BankingStage, SVM Executor, and Entry—while removing the consensus mechanisms. This makes the SVM lighter and more adaptable to the needs of a rollup, where the focus is on efficiently processing L2 transactions derived from L1 data.

Integration with the Derivation Pipeline

The Decoupled SVM’s integration with the derivation pipeline is crucial for maintaining the integrity and security of a rollup. The derivation pipeline is responsible for processing inputs from the L1, such as block headers and deposit transactions, and packaging this data into L2 blocks that the SVM will execute.

In a rollup, every L2 block is directly tied to an L1 block, ensuring that the state of the L2 is always a derivative of the L1 state. The derivation pipeline ensures that:

1. L1 Data Integration: The pipeline processes relevant data from L1, such as deposit transactions, and ensures they are included in L2 blocks. This guarantees that all critical L1 events are reflected in the L2 state.

2. Transaction Packaging: Once the L1 data is integrated, the pipeline packages this information along with new L2 transactions (originating from L2 clients) into a BlockPayload. This BlockPayload is then passed to the SVM Executor for processing.

3. State Consistency: By tightly integrating the SVM with the derivation pipeline, the Decoupled SVM ensures that the state transitions on L2 are consistent with L1 data. This is vital for maintaining the integrity of the rollup, as any discrepancies between L1 and L2 could undermine the security guarantees of the rollup.

The decoupling of the SVM from Solana’s consensus mechanisms allows the derivation pipeline to control block production on L2, ensuring that the L2 state is accurately derived from the L1 state without being constrained by Solana's original consensus protocols.

Fault Proofs and Security Enhancements

In optimistic rollups, fault proofs are essential for maintaining trust in the system. They allow users to challenge state transitions they believe are incorrect, ensuring that only valid state transitions are finalized. In the context of the Decoupled SVM, fault proofs are particularly important because they must cover both the execution of transactions and the derivation of L2 blocks from L1 data.

The Decoupled SVM’s integration with the derivation pipeline ensures that fault proofs can be applied to the entire process, from the inclusion of L1 deposit transactions to the execution of L2 transactions. This comprehensive approach significantly enhances the security of the rollup, making it resistant to various types of attacks, including those that target the derivation process.