Begin block

The base fee is calculated at the beginning of each block.

Base Fee

Disabling base fee

We introduce two parameters : NoBaseFeeand EnableHeight

NoBaseFee controls the feemarket base fee value. If set to true, no calculation is done and the base fee returned by the keeper is zero.

EnableHeight controls the height we start the calculation.

• If NoBaseFee = false and height < EnableHeight, the base fee value will be equal to base_fee defined in the genesis and the BeginBlock will return without further computation.

• If NoBaseFee = false and height >= EnableHeight, the base fee is dynamically calculated upon each block at BeginBlock.

Those parameters allow us to introduce a static base fee or activate the base fee at a later stage.

Enabling base fee

To enable EIP1559 with the EVM, the following parameters should be set :

• NoBaseFee should be false

• EnableHeight should be set to a positive integer >= upgrade height. It defines at which height the chain starts the base fee adjustment

• LondonBlock evm's param should be set to a positive integer >= upgrade height. It defines at which height the chain start to accept EIP1559 transactions

Calculation

The base fee is initialized at EnableHeight to the InitialBaseFee value defined in the genesis file.

The base fee is after adjusted according to the total gas used in the previous block.

parent_gas_target = parent_gas_limit / ELASTICITY_MULTIPLIER

if EnableHeight == block.number
    base_fee = INITIAL_BASE_FEE
else if parent_gas_used == parent_gas_target:
    base_fee = parent_base_fee
else if parent_gas_used > parent_gas_target:
    gas_used_delta = parent_gas_used - parent_gas_target
    base_fee_delta = max(parent_base_fee * gas_used_delta / parent_gas_target / BASE_FEE_MAX_CHANGE_DENOMINATOR, 1)
    base_fee = parent_base_fee + base_fee_delta
else:
    gas_used_delta = parent_gas_target - parent_gas_used
    base_fee_delta = parent_base_fee * gas_used_delta / parent_gas_target / BASE_FEE_MAX_CHANGE_DENOMINATOR
    base_fee = parent_base_fee - base_fee_delta