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VM Differences

The Core Space VM is compatible with the EVM in most cases, but there are some differences. This page lists the differences between the two.

Address Calculation​

The EOA and contract address calculation in core space is different from Ethereum.

Check EOA address and Contract Address for more details.

1820 Registry​

note

Certain EIPs relying on EIP-1820, for example, EIP-777, is not recommended to be used any more. Using ERC-20 would be good enough for most cases. You can check Exploring ERC777 Tokens: Vulnerabilities and Potential DOS Attacks on Smart Contracts for why.

The 1820 registry is a contract that stores the addresses of other contracts that implement certain interfaces. It is used to implement the EIP-1820 standard. The 1820 registry is deployed at Core Space hex40 address 0x88887eD889e776bCBe2f0f9932EcFaBcDfCd1820

Block Gas Limit​

The core space block gas limit is 54 million gas after v2.4.0.

block.number​

The block.number is the sequence number in whole tree-graph.

Internal Contracts​

Core Space has some internal contracts that are not in Ethereum.

Gas Pricing​

Storage Collateral​

Conflux Core introduced the Collateral for Storage (CFS) mechanism as a pricing method for using storage. In principle, this mechanism requires locking a certain amount of funds as collateral to occupy storage space. (each storage entry occupies 64B (B is Bytes, byte), which is the size of the key/value pair in the world state). This collateral remains locked until the corresponding storage space is either released or taken over by others.

Please refer to Storage for more details.

BLOCKHASH Gas Pricing​

While Ethereum allows querying blocks in the range [n-256, n-1] for block height n, Conflux supports a larger range of [n-65535, n] (CIP-133). Corresponding gas prices for BLOCKHASH are adjusted as follows:

  • Ethereum: 20 gas (uniform for all cases)
  • Conflux: 2100 gas (for the range [n-65535, n-257]), 100 gas (for blocks in [n-256, n-1])

Gas Refunds​

  • Gas refund cap: In Ethereum, if a transaction's gas limit exceeds the actual gas cost, the remaining gas is fully refunded. In contrast, Conflux refunds a maximum of 1/4 of the gas limit. Check Gas Limit, Gas Used, and Gas Charged for more details.
  • EIP-7702 refund difference: When updating delegate addresses (rather than creating a new delegation), Conflux does not issue the 12500 gas refund that Ethereum provides.

Transaction Gas limit​

  • A transaction's gas limit should be no less than 100 times the byte size of its call data. Check CIP-130 for more details.

Transaction Balance Handling​

When transaction balance cannot afford maximum cost (max gas price × gas limit + tx value):

  • Ethereum: Transaction fails without nonce increment or fee deduction
  • Conflux: Nonce is incremented and maximum effective gas price × gas limit is deducted (or entire balance if insufficient)

The maximum effective gas price equals to gasPrice if gasPrice is specified otherwise min(maxFeePerGas, baseFeePerGas+maxPriorityFeePerGas).

Others​

Resources​