System Config
Table of Contents
Overview
The SystemConfig is updated to allow for dynamic EIP-1559 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) | abi.encode(uint256(0), (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) | abi.encode((uint256(_denominator) << 32) | _elasticity) | Modifies the EIP-1559 denominator and elasticity |
Note that the above encoding is the format emitted by the SystemConfig event, which differs from the format in extraData from the block header.
Initialization
The following actions should happen during the initialization of the SystemConfig:
emit ConfigUpdate.BATCHERemit ConfigUpdate.FEE_SCALARSemit ConfigUpdate.GAS_LIMITemit ConfigUpdate.UNSAFE_BLOCK_SIGNER
Intentionally absent from this is emit ConfigUpdate.EIP_1559_PARAMS.
As long as these values are unset, the default values will be used.
Requiring 1559 parameters to be set during initialization would add a strict requirement
that the L2 hardforks before the L1 contracts, and this is complicated to manage in a
world of many chains.
Modifying EIP-1559 Parameters
A new SystemConfig UpdateType is introduced that enables the modification of
EIP-1559 parameters. This allows for the chain
operator to modify the BASE_FEE_MAX_CHANGE_DENOMINATOR and the ELASTICITY_MULTIPLIER.
Interface
EIP-1559 Params
setEIP1559Params
This function MUST only be callable by the chain governor.
function setEIP1559Params(uint32 _denominator, uint32 _elasticity)
The _denominator and _elasticity MUST be set to values greater to than 0.
It is possible for the chain operator to set EIP-1559 parameters that result in poor user experience.
eip1559Elasticity
This function returns the currently configured EIP-1559 elasticity.
function eip1559Elasticity()(uint32)
eip1559Denominator
This function returns the currently configured EIP-1559 denominator.
function eip1559Denominator()(uint32)