Precompiles

MegaETH precompile gas overrides — KZG Point Evaluation and ModExp cost schedules diverging from standard Ethereum.

This page specifies precompile behavior in MegaETH. MegaETH inherits the standard precompile set from the underlying EVM baseline unless explicitly overridden on this page.

Motivation

MegaETH also overrides the gas cost of selected precompiles to better match the actual computation they consume. If a precompile is materially underpriced, an attacker can pack many such calls into a transaction or block and impose disproportionate computation on the sequencer. The overrides on this page exist to reduce that denial-of-service risk by bringing charged gas closer to actual execution cost.

Specification

The overrides on this page begin at MiniRex; under Equivalence a node runs the inherited precompile table unmodified. A node MUST inherit the standard precompile set from the Optimism Isthmus / Ethereum Prague baseline except for the following MegaETH-specific overrides. A node MUST preserve these MegaETH-specific overrides whenever it refreshes or reselects its internal precompile table. If multiple MegaETH specs share the same inherited upstream baseline, an implementation MUST NOT reconstruct the MegaETH precompile table from the upstream baseline identifier alone.

Precompile	Address	MegaETH-Specific Behavior
KZG Point Evaluation	0x0A	Fixed gas cost of KZG_POINT_EVALUATION_GAS_COST
ModExp	0x05	Uses the Osaka / EIP-7883 pricing schedule

For KZG Point Evaluation, if the supplied gas is less than KZG_POINT_EVALUATION_GAS_COST, the precompile MUST fail with OutOfGas. Otherwise the precompile runs, and on a successful return the node MUST charge exactly KZG_POINT_EVALUATION_GAS_COST gas for it.

The fixed charge applies to a successful return only. If the precompile runs and then fails — for example on malformed input — the inherited EVM's precompile-failure semantics apply unchanged, and the caller loses the entire gas limit it forwarded rather than the fixed cost. The compute gas recorded for that failure is a separate amount; see Compute Gas Accounting.

For ModExp, the node MUST use the Osaka / EIP-7883 pricing schedule instead of the earlier inherited pricing schedule.

One input shape deviates from the EIP-7883 formula: a call whose header declares base_length = 0 and modulus_length = 0 MUST be charged the flat MODEXP_MIN_GAS_COST minimum, regardless of the declared exponent length. This preserves the behavior of the implementation the schedule was adopted through, which returned the minimum before computing the formula cost; EIP-7883 as written has no such special case, and under its formula a large declared exponent length always prices these inputs above the minimum. The EIP-7823 input-size limits MUST still be enforced before this short-circuit: an oversized declared length fails the call even when base and modulus lengths are zero.

All other precompiles MUST behave according to the inherited EVM baseline unless explicitly overridden elsewhere in this specification.

Constants

Constant	Value	Description
KZG_POINT_EVALUATION_GAS_COST	100,000	Fixed gas cost for the KZG Point Evaluation precompile
MODEXP_MIN_GAS_COST	500	Minimum charge for the ModExp precompile; the flat charge for the zero-base-and-modulus short-circuit

Security Considerations

This page has no security considerations.

Spec History

• MiniRex introduced the stable KZG Point Evaluation and ModExp overrides.
• Rex, Rex1, Rex2, and Rex3 retain the same stable overrides.
• Rex4 retains the same stable overrides; no change to KZG or ModExp pricing.
• Rex5 refines the KZG error-path compute-gas recording.