Vitalik Buterin suggests replacing EVM with RISC-V to scale Ethereum

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“ETH sucks, it has no value accrual, and the L1 is dead,” says everyone with an X account. “Want Ethereum to return to its glory days? Forget the L2 roadmap — scale the L1!”

It appears the Ethereum inner circles are finally listening.

A new Vitalik blog post published yesterday lays out an exploratory long-term and “radical” plan to scale the execution layer of the Ethereum L1. It’s a seemingly stark acknowledgement of all the past year’s complaints. 

The upgrade, if done, may bring efficiency gains of over 100x to the L1, Vitalik says.

How would it actually be done?

Vitalik’s proposal looks to replace the beloved Ethereum Virtual Machine (EVM) with a general purpose RISC-V virtual machine — all while maintaining the backward-compatibility of old EVM contracts.

What is a RISC-V virtual machine?

“RISC-V” is a hardware instruction set architecture (ISA). The simplest way to think of it is as a standardized language that defines communication between the hardware and software.

Though RISC-V was not originally built for blockchain purposes, its open design allowed crypto developers to leverage it for building virtual machines that could generate zero-knowledge proofs at far lower resource costs than the EVM.

The outcome is what’s known as a zero knowledge virtual machine (zkVM), which enables developers to write applications in high level languages like Rust without needing to be trained in cryptography.

In the absence of zkVMs, companies that want to leverage zk tech to build a privacy-secure application to process payroll/healthcare data would need to spend much more time writing custom zk circuits that cannot be easily changed after deployment (unlike a zkVM where devs could simply recompile RISC-V code).

Today, there are already several zkVMs built on top of RISC-V, including Succinct’s SP1, Risc Zero’s “RISC0,” a16z’s Jolt, Axiom’s OpenVM, Polygon’s Miden and more.

zkVMs have largely been talked about in the context of usage on L2 zkrollups. Vitalik’s latest blog post shifts the focus to L1 usage.

It’s an ambitious goal, given the obviously far more monumental task of implementation, given the coordination problems of upgrading the L1.

What about zkEVMs?

What does this mean, however, for zkEVMs — the interim solution for scalability? zkEVMs are more customized to an EVM instruction set, unlike the more general purpose zkVM.

Vitalik acknowledges in his post that zkEVMs will remain a “medium term” stopgap solution for L1 scalability. 

Yet, current zkEVM proving remains resource intensive. Based on data from Succinct’s zkEVM proving of the EVM execution layer, ~59% of time spent verifying transactions comes from executing EVM code — a bottleneck inherent to the EVM’s design.

Source: Ethereum Magicians

Succinct co-founder Kshitij Kulkarni echoes this view, claiming that the EVM interpreter “adds up to an 800x overhead to zkVM proving times. The EVM is very inefficient for zk.”

RISC-V based VMs would eliminate the need for the interpreter, thereby removing key bottlenecks in the EVM, which could reduce proving overhead by 50-100x.

Others question whether RISC-V is necessarily the better choice over Wasm.

“There are pros and cons for both RISC-V or Wasm. Wasm could be better because it offers the benefits that EOF (EVM Object Format) is trying to add i.e., better support for static analysis. It’s a win for Ethereum L1 regardless of the exact approach,” 1kx research partner Wei Dai told Blockworks.

In conclusion

Ethereum’s major upcoming Pectra upgrade brings with it changes, including expansion of blob data availability (EIP-7691), account abstraction (EIP-7702), and raised ETH staking limits (EIP-7251). These are all welcome changes, but notably do not bring any tangible upgrades that will buttress ETH as an “ultrasound money” asset. 

But one can at least take heart in the fact that the Ethereum ship seems to be slowly turning in that direction. 

Don’t expect these changes — even if it gets buy-in from the community — to come any time soon.

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