L1 Block Attributes

L1 attributes transaction changes in the Isthmus upgrade, extending calldata to include operator fee scalar and constant parameters.

Overview

The L1 block attributes transaction is updated to include the operator fee parameters.

Input arg	Type	Calldata bytes	Segment
	0-3	n/a
baseFeeScalar	uint32	4-7	1
blobBaseFeeScalar	uint32	8-11
sequenceNumber	uint64	12-19
l1BlockTimestamp	uint64	20-27
l1BlockNumber	uint64	28-35
basefee	uint256	36-67	2
blobBaseFee	uint256	68-99	3
l1BlockHash	bytes32	100-131	4
batcherHash	bytes32	132-163	5
operatorFeeScalar	uint32	164-167	6
operatorFeeConstant	uint64	168-175

Note that the first input argument, in the same pattern as previous versions of the L1 attributes transaction, is the function selector: the first four bytes of keccak256("setL1BlockValuesIsthmus()").

In the activation block, there are two possibilities:

• If Isthmus is active at genesis, there are no transactions in the activation block and therefore no L1 Block Attributes transaction to consider.
• If Isthmus activates after genesis setL1BlockValuesEcotone() method must be used. This is because the L1 Block contract will not yet have been upgraded.

In each subsequent L2 block, the setL1BlockValuesIsthmus() method must be used.

When using this method, the pre-Isthmus values are migrated over 1:1 and the transaction also sets the following new attributes to the values from the SystemConfig:

• operatorFeeScalar
• operatorFeeConstant