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Azul: Execution Engine

EVM Changes

Transaction Gas Limit Cap

EIP-7825 introduces a protocol-level maximum gas limit of 16,777,216 (2^24) per transaction. Transactions exceeding this cap are rejected during validation.

Base adopts the same cap as L1 to maximize Ethereum equivalence.

Upper-Bound MODEXP

EIP-7823 caps MODEXP precompile inputs to a maximum of 1024 bytes per field. Calls with larger inputs are rejected.

MODEXP Gas Cost Increase

EIP-7883 raises the MODEXP precompile minimum gas cost from 200 to 500 and triples the general cost calculation.

CLZ Opcode

EIP-7939 adds a new CLZ opcode that counts the number of leading zero bits in a 256-bit word, returning 256 if the input is zero.

secp256r1 Precompile Gas Cost

EIP-7951 specifies the secp256r1 precompile at address 0x100 with a gas cost of 3,450.

Base already has the p256Verify precompile at the same address (added in Fjord via RIP-7212) with a gas cost of 3,450. From Azul, the gas cost increases to 6,900 to match the L1 gas cost specified in EIP-7951, maintaining strict equivalence with L1 precompile pricing.

Networking Changes

eth/69

EIP-7642 updates the Ethereum wire protocol to version 69, removing legacy fields from the Status message and simplifying the handshake.

Remove Account Balances & Receipts

The FlashblocksMetadata payload transmitted over the Flashblocks WebSocket is simplified in Azul. The new_account_balances and receipts fields are removed. The access_list field remains but will not be populated in Azul.

Before: 
{
  "block_number": 43403718,
  "new_account_balances": {
    "0x4200000000000000000000000000000000000006": "0x35277a9715c6df1c99de"
  },
  "receipts": {
    "0x1ef9be45b3f7d44de9d98767ddb7c0e330b21777b67a3c79d469be9ffab091dd": {
      "cumulativeGasUsed": "0x177d7bd",
      "logs": [],
      "status": "0x1",
      "type": "0x2"
    }
  },
  "access_list": null
}
After: 
{
  "block_number": 43403718,
  "access_list": null
}

RPC Changes

Engine API Usage

At and after Azul activation, block production and import use the following Engine API methods:

  • engine_forkchoiceUpdatedV3 for starting block builds and forkchoice synchronization.
  • engine_getPayloadV5 for fetching built payloads.
  • engine_newPayloadV4 for importing payloads into the execution engine.

engine_getPayloadV5 returns a V5 envelope, but the contained execution payload is still V4-shaped. As a result, payload insertion continues through engine_newPayloadV4 (there is no engine_newPayloadV5 path used by Base Azul clients).

Azul constraints for this flow:

  • Blob-related Engine API inputs are constrained to empty values:
    • expectedBlobVersionedHashes MUST be an empty array.
    • blobsBundle in engine_getPayloadV5 responses is expected to be empty.
  • executionRequests in engine_newPayloadV4 MUST be an empty array.

eth_config RPC Method

EIP-7910 introduces the eth_config JSON-RPC method, which returns chain configuration parameters such as fork activation timestamps.

Base Azul exposes eth_config using the standard EIP-7910 response schema.

The Base-specific behavior is:

  • blobSchedule is always returned as zeroed values for current, next, and last. Base does not support native blob transactions, so it must not advertise synthetic Ethereum blob schedule defaults.
  • precompiles reflects the active EVM precompile set for that fork. This includes the standard Ethereum precompiles plus any Base-active additions documented in the precompiles specification.
  • systemContracts is limited to the contracts representable by EIP-7910. On Base this means:
    • BEACON_ROOTS_ADDRESS is included once Ecotone is active.
    • HISTORY_STORAGE_ADDRESS is included once Isthmus is active.
    • DEPOSIT_CONTRACT_ADDRESS, CONSOLIDATION_REQUEST_PREDEPLOY_ADDRESS, and WITHDRAWAL_REQUEST_PREDEPLOY_ADDRESS are omitted.

Base-specific predeploys and other OP Stack system contracts documented in the predeploys specification are not serialized into eth_config unless they are part of the EIP-7910 schema.