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This feature ships with Upgrade 19. It is non-functional until the upgrade is approved by governance and activated on Mainnet.
Upgrade 19 activates a subset of the Osaka EIPs on L2 — specifically the changes that are applicable to OP Stack chains. Not every Osaka EIP is relevant to L2 execution; only those that affect L2 transaction processing or precompile behavior are included. The activated changes introduce a per-transaction gas limit and updated gas costs for two precompiles.

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EIP-7825: Per-transaction gas limit

EIP-7825 introduces a maximum gas limit that any single L2 transaction can request. After Upgrade 19, transactions whose gas limit exceeds this threshold are rejected as invalid by the execution layer. The EIP-7825 limit is 2^24 = 16,777,216 gas. It is enforced by the execution client (op-reth).

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Deposit transactions are exempt

Deposit transactions (L1-to-L2 messages) are not subject to the EIP-7825 limit. Deposits are already capped at 20M gas total per L1 block, and rejecting a deposit on L2 that was accepted on L1 would cause permanent ETH loss. System deposit transactions (e.g., network upgrade transactions) are also exempt.

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Impact on app developers

Most transactions will not be affected. The limit is designed to be well above gas requirements for typical application interactions. If your application submits transactions with very high gas limits, verify they remain within the new threshold. If your application constructs raw transactions programmatically and sets a gas limit above the threshold, those transactions will fail. Update your gas limit logic or rely on standard eth_estimateGas responses — estimates will not return a value above the limit.

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MODEXP gas cost and input size changes

EIP-7883 raises the MODEXP precompile (0x05) gas cost floor from 200 to 500 gas. EIP-7823 caps the modulus size at 1024 bytes — calls with a larger declared modulus fail.
  • For contracts using MODEXP: re-run gas benchmarks and update any hardcoded gas values. Verify that your modulus inputs are within the 1024-byte limit.
  • For contracts not using MODEXP: no action required.

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P256VERIFY gas cost change

EIP-7951 raises the P256VERIFY precompile (0x100) gas cost from 3,450 (RIP-7212) to 6,900 gas.
  • For contracts using P256VERIFY: re-run gas benchmarks and update any hardcoded gas values.
  • For contracts not using P256VERIFY: no action required.

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CLZ opcode

EIP-7939 introduces the Count Leading Zeros opcode (CLZ, 0x1e). Given a uint256, it returns the number of leading zero bits (0–255).
  • For contract developers: the opcode is now available for use. Existing contracts are not affected.
  • For toolchain authors: assemblers and decompilers that treat unknown opcodes as invalid should add CLZ support.

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Summary of changes

ChangeEIPOPCODEImpact
Per-transaction gas limit (16,777,216 gas)EIP-7825n/aTransactions above the limit are invalid (deposits exempt)
MODEXP gas floor increase (200 → 500 gas)EIP-78830x05Gas cost changes
MODEXP modulus size cap (1024 bytes)EIP-78230x05Inputs over 1024-byte modulus fail
P256VERIFY gas cost increase (3,450 → 6,900 gas)EIP-79510x100Gas cost changes
CLZ (Count Leading Zeros) opcodeEIP-7939opcode 0x1eNew opcode available

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References