hyperledger-besu-evm.md

Hyperledger Besu EVM

The EthereumJ virtual machine was replaced with the Hyperledger Besu virtual machine in the Hedera Services release 0.19 as a result of HIP-26. This migration enables Hedera to maintain parity with Ethereum Mainnet evolutions such as the EVM container formats, new opcodes, and precompiled contracts. The Besu integration is configured to use the “London” hard fork of Ethereum Mainnet.

London Hard Fork

The smart contract platform is upgraded to support the EVM visible changes for the “London” hard fork. This includes changes introduced in the “Istanbul” and “Berlin” hard forks. Changes relating to block production, data serialization, and the fee market will not be implemented because they are not relevant to Hedera’s architecture.

Starting in the Hedera Services 0.22 release, the __ intrinsic gas cost and input data will be charged. The intrinsic gas cost is a constant that is charged before any code is executed. The intrinsic gas cost is 21,000 gas. The input data is 16 gas per non-zero byte and 4 gas per zero byte. The input data is the data provided to the external contract function parameters when calling a contract. To learn more about gas fees check out this page.

Gas Schedule

The Hedera Smart Contract Service will use the Gas Schedule from the "London" hard fork. Notable changes include warm/cold account access and refund reductions.

Warm and Cold Account and Slot Access

The "Berlin" hard fork introduced the notion of warm and cold accounts and storage slots. The first access to an account or storage slot in a transaction will need to pay the "cold" costs and all subsequent calls will pay the lower "warm" access costs. EIP-2929 contains the full details of the new cost scheduling.

Hedera does not at this time allow for "pre-warming" addresses and storage slots as part of the transaction as seen in EIP-2930. Future HIPs may support this scheme.

Gas Refund Reductions and Eliminations

In the London gas schedule, the amount of gas that can be returned from storage access usage patterns has been significantly reduced. Account refunds from SELFDESTRUCT have been completely removed.

Table of Gas Cost Changes

The current opcode gas fees are reflective of the 0.22 Hedera Service release.

Operation	London Cost (Gas)	Current Hedera (Gas)
Code deposit	200 * bytes	Max of London or Hedera
BALANCE (cold account)	2600	2600
BALANCE (warm account)	100	100
EXP	10 + 50/byte	10 + 50/byte
EXTCODECOPY (cold account)	2600 + Mem	2600 + Mem
EXTCODECOPY (warm account)	100 + Mem	100 + Mem
EXTCODEHASH (cold account)	2600	2600
EXTCODEHASH (warm account)	100	100
EXTCODESIZE (cold account)	2600	2600
EXTCODESIZE (warm account)	100	100
LOG0, LOG1, LOG2, LOG3, LOG4	375 + 375*topics + data Mem	Max of London or Hedera
SLOAD (cold slot)	2100	2100
SLOAD (warm slot)	100	100
SSTORE (new slot)	22,100	Max of London or Hedera
SSTORE (existing slot, cold access)	2,900	2,900
SSTORE (existing slot, warm access)	100	100
SSTORE refund	Only transient storage slots	Only transient storage slots
CALL et al. (cold recipient)	2,600	2,600
CALL et al. (warm recipient)	100	100
CALL et al. Hbar/Eth Transfer Surcharge	9,000	9,000
CALL et al. New Account Surcharge	25,000	revert
SELFDESTRUCT (cold beneficiary)	2600	2600
SELFDESTRUCT (warm beneficiary)	0	0

The terms 'warm' and 'cold' in the above table correspond with whether the account or storage slot has been read or written to within the current smart contract transaction, even if within a child call frame.

'CALL et al.' includes with limitation CALL, CALLCODE, DELEGATECALL, and STATICCALL

Reference HIP-206