The Innovative Path of Ethereum: Exploring the Possibility of RISC-V as a Replacement for EVM

The co-founder of Ethereum recently proposed a long-term plan in the community: to replace the existing execution layer virtual machine (EVM) with an open-source RISC-V instruction set architecture. This proposal has been likened to the consensus layer's Beam Chain and is seen as the potential only way to break through the performance bottleneck of the execution layer and simplify protocol logic. Especially in terms of zero-knowledge proof (ZK Proof) efficiency, it is expected that replacing the EVM could achieve an optimization improvement of up to 100 times. This proposal aims to address the bottleneck issues Ethereum currently faces in ZK proof efficiency, block construction complexity, data availability, and other aspects.

1. Limitations of EVM and Advantages of RISC-V

Challenges Facing EVM:

1. Outdated architecture: The 256-bit stack structure is incompatible with modern CPUs, resulting in low execution efficiency of the ZK-EVM.
2. ZK Proof Bottleneck: A large amount of resources is used to execute the EVM itself, which limits the efficiency of ZK proofs.
3. Maintenance difficulties: Years of accumulated features have led to chaotic specifications, making it difficult to remove certain functions.
4. Development limitations: The non-standard instruction set restricts cross-language support, making it difficult for mainstream languages to efficiently compile to EVM bytecode.

Advantages of RISC-V:

1. High efficiency: As a streamlined instruction set of a real CPU, it is hardware-friendly and supports JIT optimization and even hardware acceleration.
2. ZK Optimization: Directly generates circuits for RISC-V instructions, simplifying the ZK proof process.
3. Mature toolchain: Supports mainstream languages such as Rust/C/C++, lowers the development threshold, and expands the ecosystem.
4. Universal Standards: Existing blockchain projects have successfully adopted it, with practical case studies.

2. Replacement Paths and Challenges

Replacement Plan:

1. Dual VM Coexistence: EVM and RISC-V run in parallel, with new contracts optionally using RISC-V to ensure compatibility during the transition period.
2. On-chain Interpreter: All EVM contracts are interpreted and executed through on-chain RISC-V contracts.
3. Interpreter Plugin Mechanism: Treat the interpreter as a protocol element, leaving room for the introduction of other VMs in the future.

Technical Challenges:

1. Execution Performance: RISC-V needs to be simulated on x86 chips, and initial efficiency may be lower than that of the optimized EVM.
2. Gas pricing reconstruction: A new Gas model needs to be defined for RISC-V instructions to ensure fairness and security.
3. Security Sandbox: Limit system calls, prevent self-modifying code, ensure deterministic execution.
4. Development tool adaptation: Update compilers, debuggers, and security audit tools to support RISC-V bytecode.
5. Migration Compatibility: Some contracts rely on EVM features, and a careful design of compatibility layers or fallback mechanisms is required.

3. Impact on Existing Scalability Solutions

RISC-V will not replace existing scaling solutions, but will serve as an infrastructure optimization:

1. Layer 2: RISC-V improves L1 processing efficiency and ZK verification performance, aiding Rollup in submitting data at a lower cost and faster.
2. Data Sharding and EIP-4844: The data availability bottleneck still needs to be resolved through blobs and Danksharding, and RISC-V does not directly affect on-chain data capacity.
3. FaaS, MEV: These features are independent of the virtual machine architecture and will not become invalid due to the advancement of RISC-V.

4. Community Feedback and Related Attempts

Community Divergence:

• Supporters believe this is a necessary upgrade to address the challenges of high-performance blockchain and will help attract traditional developers.
• Conservatives are worried about the difficulty of implementation, the heavy historical burden, and the high cost of updating the ecological toolchain.

Similar project reference:

1. Move VM (Aptos/Sui): A brand new resource-oriented VM with strong language safety, but not compatible with EVM.
2. FuelVM: A new VM designed for parallel processing, paired with the Sway language, with limited compatibility.
3. WASM (Stylus): Introduced WASM as a contract language in L2, which has been implemented on a certain L2 platform.
4. A certain blockchain project: The use of RISC-V as a contract VM on the mainnet serves as a precedent, providing practical reference for Ethereum.

V. Future Impact Outlook

If Ethereum switches to RISC-V:

1. Developer Experience:

   • Languages like Solidity/Vyper can still be used, only the compiler backend has changed.
   • It may open up the possibility of writing contracts in new languages like Rust/C, but migration is not mandatory.

2. Operating costs and performance:

   • Improved execution efficiency will lead to higher Gas limits and lower fees.
   • RISC-V contracts may reduce dependence on precompiled contracts, and the Gas model is closer to the cost of ZK proofs.

3. Ecological Compatibility and Development:

   • Existing contracts can continue to operate during the dual VM co-existence period, and new contracts will gradually adopt RISC-V.
   • The infrastructure needs to support the new bytecode format, which may cause inter-chain compatibility changes.

4. Security and Stability:

   • The new architecture needs extensive testing and formal verification to enhance protocol reliability.
   • A more streamlined execution layer is beneficial for auditing and attack surface control.

Conclusion

The proposal to replace EVM with RISC-V represents Ethereum's deep contemplation on the future limits of performance and the simplicity of the protocol. This proposal is still in the early discussion phase and its implementation is expected to be a multi-year process, requiring overcoming various challenges across technology, community, and ecosystem. It is not about overthrowing the existing path, but rather strengthening the foundation and preparing for the future.

This proposal can be seen as a bet on the future and a deep exploration of "whether the underlying structure is worth reshaping." As Ethereum co-founder said: "To achieve an order of magnitude improvement, this radical change may be the only viable path."