Ethereum gets huge mainnet upgrade tomorrow – Here’s why you should care about ETH’s ‘sloping side road’

Ethereum’s Fusaka upgrade activates Dec. 3, deploying a suite of changes designed to increase rollup throughput, tighten gas markets, and add native support for passkey-style signatures.

The fork introduces PeerDAS data-availability sampling, doubles the default block gas limit, and prepares the network for blob-only parameter expansions scheduled for later this month and January.

Fusaka is named after the star Fulu (‘auxiliary road’) and the city of Osaka (‘slope or hill’), continuing Ethereum’s convention of pairing a star and a city.

Editor’s Note: Sloping side road’ is a playful nod to the Fulu + Osaka mash-up, not an official translation.

Data availability gets a scaling layer

The central technical shift is PeerDAS, formalized in EIP-7694. The protocol allows nodes to verify that blob data exists by sampling small pieces rather than downloading entire blobs.

That removes a scaling bottleneck introduced by EIP-4844 and creates a path to push blob throughput up by roughly an order of magnitude over time.

Higher blob capacity translates directly into cheaper layer-two transaction fees, as rollups compress user transactions into blobs and post them to Ethereum’s base layer.

Fusaka also raises the default gas limit per block to 60 million gas, up from the 30 million configuration set after the Merge.

The increase doubles the L1 block gas budget, providing more room for both standard transactions and blob processing.

Two follow-on “Blob Parameter Only” forks, BPO1 on Dec. 9 and BPO2 on Jan. 7, will adjust blob parameters without additional code changes, further expanding capacity.

Blob fee market rewired

EIP-7918 ties the minimum blob base fee to execution gas, preventing blob prices from collapsing to near zero while L1 gas remains expensive.

The change keeps the data-availability market economically rational as usage fluctuates. Previously, blob fees could diverge sharply from execution costs, creating arbitrage opportunities and distorting rollup economics.

A set of related Ethereum Improvement Proposals (EIPs) hardens several heavy opcodes and transaction limits. The EIPs are 7823, 7825, 7883, and 7934.

The proposals cap ModExp precompile input sizes, raise its gas cost, introduce a transaction gas limit ceiling, and enforce an RLP block size limit. These constraints reduce denial-of-service attack surface and make worst-case client workloads more predictable.

Developer tools and cryptographic hooks

EIP-7939 introduces a count-leading-zeros opcode that makes bit-manipulation, integer logarithms, and randomness logic cheaper and simpler on-chain.

The addition benefits DeFi protocols and cryptographic contracts that rely on efficient bitwise operations.

Deterministic proposer lookahead, specified in EIP-7917, gives validators a fixed schedule of who will propose blocks.

MEV relays and staking operators can use the more precise timeline to coordinate more safely and efficiently, reducing uncertainty in block-production workflows.

EIP-7951 adds a native precompile for the secp256r1 curve, the same cryptographic standard used by Apple Secure Enclave, Android Keystore, and WebAuthn.

Wallets and smart account schemes can now verify passkey-style signatures directly on Ethereum, enabling FaceID and TouchID authentication flows without custom bridges or circuits.

The precompile removes a major friction point for consumer-facing applications that rely on biometric hardware.

Immediate and phased rollout

Fusaka activates at block height on Dec. 3, with the first blob-parameter adjustment following six days later. BPO2 lands Jan. 7, completing the initial capacity expansion.

The phased rollout allows node operators and rollup teams to monitor blob usage and client performance before the next parameter increase.

The upgrade does not introduce consensus-layer changes to staking or validator incentives. All modifications target execution-layer throughput, gas mechanics, and developer primitives.

Validators running updated clients will process the new opcodes and blob logic without changes to their staking setup.

Fusaka represents Ethereum’s most throughput-focused upgrade since EIP-4844 introduced blobs in March 2024. The fork doubles block gas capacity, scales data-availability sampling, and adds cryptographic hooks for mainstream authentication hardware.

The combination positions Ethereum to absorb higher rollup activity without proportional fee increases, while giving developers new primitives for on-chain computation and user onboarding.