EIP-7907 raises the contract code size limit to 64KB and meters extra gas for loading code beyond 24KB; it also increases the initcode limit to 128KB.
It lets developers deploy larger contracts while paying for the extra resource cost, avoiding DoS risk.
This EIP adds gas metering for excess code loading, introducing a gas cost of 2 gas per (32 byte) word for contract code exceeding 24KB (24576 bytes). It builds on EIP-7954, which raises the contract code size limit to 64KB (65536 bytes) and the initcode size limit to 128KB (131072 bytes), without changing either limit.
EIP-170 introduced a 24KB contract code size limit to prevent potential DoS attacks, as large contract code requires O(n) resource cost in terms of disk reads, VM preprocessing, and Merkle proof sizes, all of which are not directly compensated by gas fees. EIP-7954 raises this limit to 64KB, allowing larger contracts to be deployed.
This EIP ensures that users loading large contracts pay gas proportional to the additional resources they consume. This approach aligns with Ethereum's gas model philosophy of paying for the resources consumed.
| Name | Value | Description |
|---|---|---|
COLD_SLOAD_COST | 2100 | The cost charged for cold loading storage as defined by EIP-2929. |
WARM_STORAGE_READ_COST | 100 | The cost charged for loading warm storage as defined by EIP-2929. |
COLD_ACCOUNT_ACCESS_COST | 2600 | The cost charged for loading a cold account as defined by EIP-2929. |
GAS_PER_CODE_WORD | 2 | The cost charged per word of code loaded beyond the initial 24KB amount. |
FORK_BLKNUM | TBD | The block number of the hard fork that this EIP is activated. |
The MAX_CODE_SIZE and MAX_INITCODE_SIZE limits remain as specified in EIP-7954.
CALL, STATICCALL, DELEGATECALL, CALLCODE and EXTCODECOPY are modified so that dynamic EXCESS_CODE_COST= ceil32(excess_code_size(len(code))) * GAS_PER_CODE_WORD // 32 gas are added to the access cost if the code is cold. When the code is an EIP-7702 delegation to another account, if target account code is cold add additional gas should be accounted. Warming of the contract code is subjected to the journaling and can be reverted similar to other state warming in EIP-2930.keccak("") = "0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470") is always considered warm.| Contract | Gas changes (only opcodes that load code) | How? |
|---|---|---|
| Cold account and code | Add COLD_SLOAD_COST=2100, EXCESS_CODE_COST, and COLD_ACCOUNT_ACCESS_COST=2600 | Contract not in access list nor accessed prior in the txn |
| Warm account and cold code | Add COLD_SLOAD_COST=2100, EXCESS_CODE_COST, and WARM_STORAGE_READ_COST=100 | Already accessed balance, storage, or included in access list (EIP-2930) |
| Warm account and code | WARM_STORAGE_READ_COST=100 | Already accessed account code |
COLD_ACCOUNT_ACCESS_COST, COLD_SLOAD_COST, and WARM_STORAGE_READ_COST are defined in EIP-2929.
This EIP adds a new field to the account tuple, codesize. That is, the account tuple goes from having the following four fields, (nonce, balance, storage_root, code_hash) to (nonce, balance, storage_root, code_hash, codesize). The reason for this is that most key-value databases in use by production clients do not allow peeking at the size of a value pointed to by a given key without actually loading the full contents of the value.
To avoid forcing a full migration, the following rules are followed:
FORK_BLKNUM should additionally have its codesize written into the account tuple.codesize field, the code size is determined from the length of its bytecode when needed for gas metering. Such accounts may contain code exceeding 24KB deployed after EIP-7954 activation.The gas cost of 2 per word was chosen to account for:
This EIP introduces the gas cost as an additional cost for contracts exceeding 24KB. It could have been specified as a simpler ceil32(contract_size) * GAS_PER_CODE_WORD // 32, without hardcoding the original EIP-170 contract size limit. However, for the sake of being conservative and avoiding lowering the cost of loading existing contracts (which could be small, under the 24KB limit), the 24KB floor was added to the formula.
The EXTCODECOPY opcode could theoretically be exempt from this, since clients could just load the parts of the bytecode which are actually requested. However, this might require a change at the protocol level, since the full code is required for the block witness. For this reason, EXTCODECOPY is included in the pricing scheme, and a carveout could be considered at a later date.
This EIP introduces additional gas costs for certain operations. Specifically, CALL, STATICCALL, DELEGATECALL, CALLCODE, EXTCODESIZE, and EXTCODECOPY may now require extra gas when accessing cold contract code.
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