Isthmus: System Config

SystemConfig changes in the Isthmus upgrade, adding operatorFeeScalar and operatorFeeConstant configuration variables.

Operator Fee Parameter Configuration

Isthmus adds configuration variables operatorFeeScalar (uint32) and operatorFeeConstant (uint64) to SystemConfig to control the operator fee parameters.

ConfigUpdate

The following ConfigUpdate event is defined where the CONFIG_VERSION is uint256(0):

Name	Value	Definition	Usage
BATCHER	uint8(0)	abi.encode(address)	Modifies the account that is authorized to progress the safe chain
FEE_SCALARS	uint8(1)	(uint256(0x01) << 248) | (uint256(_blobbasefeeScalar) << 32) | _basefeeScalar	Modifies the fee scalars
GAS_LIMIT	uint8(2)	abi.encode(uint64 _gasLimit)	Modifies the L2 gas limit
UNSAFE_BLOCK_SIGNER	uint8(3)	abi.encode(address)	Modifies the account that is authorized to progress the unsafe chain
EIP_1559_PARAMS	uint8(4)	uint256(uint64(uint32(_denominator))) << 32 | uint64(uint32(_elasticity))	Modifies the EIP-1559 denominator and elasticity
OPERATOR_FEE_PARAMS	uint8(5)	uint256(_operatorFeeScalar) << 64 | _operatorFeeConstant	Modifies the operator fee scalar and constant

Initialization

The following actions should happen during the initialization of the SystemConfig:

• emit ConfigUpdate.BATCHER
• emit ConfigUpdate.FEE_SCALARS
• emit ConfigUpdate.GAS_LIMIT
• emit ConfigUpdate.UNSAFE_BLOCK_SIGNER
• emit ConfigUpdate.EIP_1559_PARAMS

These actions MAY only be triggered if there is a diff to the value.

The operatorFeeScalar and operatorFeeConstant are initialized to 0.

Modifying Operator Fee Parameters

A new SystemConfig UpdateType is introduced that enables the modification of the operatorFeeScalar and operatorFeeConstant by the SystemConfig owner.

Interface

Operator fee parameters

operatorFeeScalar

This function returns the currently configured operator fee scalar.

function operatorFeeScalar()(uint32)

operatorFeeConstant

This function returns the currently configured operator fee constant.

function operatorFeeConstant()(uint64)

setOperatorFeeScalars

This function sets the operatorFeeScalar and operatorFeeConstant.

This function MUST only be callable by the SystemConfig owner.

function setOperatorFeeScalar(uint32 _operatorFeeScalar, uint64 _operatorFeeConstant)