Ethereum Devs scale back Devnet 2 testing priorities for upcoming Fusaka hard fork

Ethereum’s upcoming Fusaka hard fork will include at least 12 Ethereum Improvement Proposals, though not all of them will be immediately tested, according to the latest All Core Dev call. This doesn't appear to include the latest edition — EIP-7939, which features a new opcode for “counting leading zeros.”

Developers aim to launch Fusaka Devnet 2 on Monday, June 23, which will prime the protocol’s execution engine for the upcoming Fusaka upgrade. On the June 19 call, developers focused on paring back expectations for Devnet 2, a testing environment.

“Whatever is not selected for Devnet 2, at least as of today, would then be intended to also just not go into the hard fork,” Ethereum Foundation researcher Ansgar Dietrichs said on the call. IEF DevOps engineer Barnabas Busa echoed the sentiment, suggesting that aspects of EIP-7951 testing be deferred to Devnet 3.

EIP-7951 is a long-promised precompile for secp256r1 — a type of cryptographic curve used in digital signatures — to unlock features such as WebAuthn-based authentication and other off-chain key signing features, including Apple Secure Enclave and Android Keystore. 

The developers also agreed to push back testing of EIP 7918 — which would add a blob fee base cost — and EIP 7892 — a blob scaling plan — into Devnet 3. (A “blob” is a type of temporarily stored data on Ethereum introduced in 2024’s Dencun upgrade that reduces transaction costs for Layer 2s by separating data storage from execution.)

While these delays extend the Fusaka testing timeline, they will also give developers time to prepare, Busa argued. 

That said, EIP-7939, the latest EIP added to the Fusaka scope, appears to be set for introduction in Devnet 2. EIP-7939 proposes adding a new opcode called CLZ (count leading zeros) to the Ethereum Virtual Machine (EVM) to reduce gas costs, decrease bytecode size, and improve efficiency.