Merge pull request #4 from ralexstokes/4788-explicit-gas-limit

add explicit gas limit to EIP-4788 system write

EIPS/eip-4788.md

@@ -227,9 +227,9 @@ The sender of the transaction can be calculated as `0x3e266d3c3a70c238bdddafef1b
 
 ### Block processing
 
-At the start of processing any execution block where `block.timestamp >= FORK_TIMESTAMP` (i.e. before processing any transactions), call `BEACON_ROOTS_ADDRESS` as `SYSTEM_ADDRESS` with the 32-byte input of `header.parent_beacon_block_root`. This will trigger the `set()` routine of the beacon roots contract. This is a system operation and therefore:
+At the start of processing any execution block where `block.timestamp >= FORK_TIMESTAMP` (i.e. before processing any transactions), call `BEACON_ROOTS_ADDRESS` as `SYSTEM_ADDRESS` with the 32-byte input of `header.parent_beacon_block_root`, a gas limit of `30_000_000`, and `0` value. This will trigger the `set()` routine of the beacon roots contract. This is a system operation and therefore:
 
-* the call must execute to completion, therefore the available gas can be considered as infinite
+* the call must execute to completion
 * the call does not count against the block's gas limit
 * the call does not follow the [EIP-1559](./eip-1559.md) burn semantics - no value should be transferred as part of the call
 * if no code exists at `BEACON_ROOTS_ADDRESS`, the call must fail silently