L1 vs L2 differences
Table of Contents
A native rollup runs the L1 program unchanged, so its differences from L1 come only from the values the rollup contract puts in the payload (see Specification). This page covers the ones visible to L2 users.
Blob-carrying transactions
Rollups have no consensus layer that handles blobs, so they cannot support blob-carrying transactions. The rollup contract fixes blob_gas_used and excess_blob_gas to zero, so any block containing a blob transaction fails validation. BLOBHASH and the point evaluation precompile are unchanged, and behave as in an L1 block without blob transactions.
RANDAO
prev_randao is an unconstrained field: the rollup contract takes it from the operator or fixes it. Existing rollups differ: Orbit stack chains return the constant 1, OP stack chains return the value from the latest L1 block synced on L2, Linea returns 2, Scroll returns 0, and ZKsync returns 2500000000000000.
Slot number
slot_number is a fixed constant for L2, whose value is still to be defined (see Specification), so the SLOTNUM opcode (EIP-7843) returns the same value in every block.
Beacon roots storage
Native rollups repurpose parent_beacon_block_root as the L1 anchor, so the EIP-4788 predeploy stores anchors rather than beacon block roots. Of the rollups surveyed, only the OP stack supports EIP-4788, while the Orbit stack, Taiko, Linea, Scroll, and ZKsync Era do not.