contract change following idea of ethereum-optimism/specs#122

packages/contracts-bedrock/src/L1/SystemConfig.sol

@@ -8,6 +8,7 @@ import { Storage } from "src/libraries/Storage.sol";
 import { Constants } from "src/libraries/Constants.sol";
 import { OptimismPortal } from "src/L1/OptimismPortal.sol";
 import { GasPayingToken, IGasToken } from "src/libraries/GasPayingToken.sol";
+import { BatchInbox } from "src/libraries/BatchInbox.sol";
 import { ERC20 } from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 
 /// @title SystemConfig
@@ -25,8 +26,7 @@ contract SystemConfig is OwnableUpgradeable, ISemver, IGasToken {
         BATCHER,
         GAS_CONFIG,
         GAS_LIMIT,
-        UNSAFE_BLOCK_SIGNER,
-        BATCH_INBOX
+        UNSAFE_BLOCK_SIGNER
     }
 
     /// @notice Struct representing the addresses of L1 system contracts. These should be the
@@ -72,9 +72,6 @@ contract SystemConfig is OwnableUpgradeable, ISemver, IGasToken {
     bytes32 public constant OPTIMISM_MINTABLE_ERC20_FACTORY_SLOT =
         bytes32(uint256(keccak256("systemconfig.optimismmintableerc20factory")) - 1);
 
-    /// @notice Storage slot that the batch inbox address is stored at.
-    bytes32 public constant BATCH_INBOX_SLOT = bytes32(uint256(keccak256("systemconfig.batchinbox")) - 1);
-
     /// @notice Storage slot for block at which the op-node can start searching for logs from.
     bytes32 public constant START_BLOCK_SLOT = bytes32(uint256(keccak256("systemconfig.startBlock")) - 1);
 
@@ -200,7 +197,7 @@ contract SystemConfig is OwnableUpgradeable, ISemver, IGasToken {
         _setGasLimit(_gasLimit);
 
         Storage.setAddress(UNSAFE_BLOCK_SIGNER_SLOT, _unsafeBlockSigner);
-        _setBatchInbox(_batchInbox);
+        BatchInbox.set(_batchInbox);
         Storage.setAddress(L1_CROSS_DOMAIN_MESSENGER_SLOT, _addresses.l1CrossDomainMessenger);
         Storage.setAddress(L1_ERC_721_BRIDGE_SLOT, _addresses.l1ERC721Bridge);
         Storage.setAddress(L1_STANDARD_BRIDGE_SLOT, _addresses.l1StandardBridge);
@@ -273,7 +270,7 @@ contract SystemConfig is OwnableUpgradeable, ISemver, IGasToken {
 
     /// @notice Getter for the BatchInbox address.
     function batchInbox() external view returns (address addr_) {
-        addr_ = Storage.getAddress(BATCH_INBOX_SLOT);
+        addr_ = BatchInbox.get();
     }
 
     /// @notice Getter for the StartBlock number.
@@ -357,21 +354,6 @@ contract SystemConfig is OwnableUpgradeable, ISemver, IGasToken {
         emit ConfigUpdate(VERSION, UpdateType.BATCHER, data);
     }
 
-    /// @notice Updates the batch inbox address. Can only be called by the owner.
-    /// @param _batchInbox New batch inbox address.
-    function setBatchInbox(address _batchInbox) external onlyOwner {
-        _setBatchInbox(_batchInbox);
-    }
-
-    /// @notice Updates the batch inbox address.
-    /// @param _batchInbox New batch inbox address.
-    function _setBatchInbox(address _batchInbox) internal {
-        Storage.setAddress(BATCH_INBOX_SLOT, _batchInbox);
-
-        bytes memory data = abi.encode(_batchInbox);
-        emit ConfigUpdate(VERSION, UpdateType.BATCH_INBOX, data);
-    }
-
     /// @notice Updates gas config. Can only be called by the owner.
     ///         Deprecated in favor of setGasConfigEcotone since the Ecotone upgrade.
     /// @param _overhead New overhead value.

packages/contracts-bedrock/src/L1/SystemConfigInterop.sol

@@ -4,6 +4,7 @@ pragma solidity 0.8.15;
 import { Constants } from "src/libraries/Constants.sol";
 import { OptimismPortalInterop as OptimismPortal } from "src/L1/OptimismPortalInterop.sol";
 import { GasPayingToken } from "src/libraries/GasPayingToken.sol";
+import { BatchInbox } from "src/libraries/BatchInbox.sol";
 import { ERC20 } from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 import { SystemConfig } from "src/L1/SystemConfig.sol";
 import { ConfigType } from "src/L2/L1BlockInterop.sol";
@@ -63,4 +64,18 @@ contract SystemConfigInterop is SystemConfig {
             ConfigType.REMOVE_DEPENDENCY, StaticConfig.encodeRemoveDependency(_chainId)
         );
     }
+
+    /// @notice Updates the batch inbox address. Can only be called by the owner.
+    /// @param _batchInbox New batch inbox address.
+    function setBatchInbox(address _batchInbox) external onlyOwner {
+        if (_batchInbox != BatchInbox.get()) {
+            BatchInbox.set(_batchInbox);
+            OptimismPortal(payable(optimismPortal())).setConfig(
+                ConfigType.SET_BATCH_INBOX,
+                StaticConfig.encodeSetBatchInbox({
+                    _batchInbox: _batchInbox,
+                })
+            );
+        }
+    }
 }

packages/contracts-bedrock/src/L2/L1Block.sol

@@ -46,9 +46,6 @@ contract L1Block is ISemver, IGasToken {
     /// @notice The versioned hash to authenticate the batcher by.
     bytes32 public batcherHash;
 
-    /// @notice The canonical batch inbox.
-    bytes32 public batchInbox;
-
     /// @notice The overhead value applied to the L1 portion of the transaction fee.
     /// @custom:legacy
     uint256 public l1FeeOverhead;
@@ -152,7 +149,6 @@ contract L1Block is ISemver, IGasToken {
             sstore(blobBaseFee.slot, calldataload(68)) // uint256
             sstore(hash.slot, calldataload(100)) // bytes32
             sstore(batcherHash.slot, calldataload(132)) // bytes32
-            sstore(batchInbox.slot, calldataload(164)) // bytes32
         }
     }
 

packages/contracts-bedrock/src/L2/L1BlockInterop.sol

@@ -6,15 +6,18 @@ import { EnumerableSet } from "@openzeppelin/contracts/utils/structs/EnumerableS
 import { GasPayingToken } from "src/libraries/GasPayingToken.sol";
 import { StaticConfig } from "src/libraries/StaticConfig.sol";
 import "src/libraries/L1BlockErrors.sol";
+import { BatchInbox } from "src/libraries/BatchInbox.sol";
 
 /// @notice Enum representing different types of configurations that can be set on L1BlockInterop.
 /// @custom:value SET_GAS_PAYING_TOKEN  Represents the config type for setting the gas paying token.
 /// @custom:value ADD_DEPENDENCY        Represents the config type for adding a chain to the interop dependency set.
 /// @custom:value REMOVE_DEPENDENCY     Represents the config type for removing a chain from the interop dependency set.
+/// @custom:value SET_BATCH_INBOX       Represents the config type for setting the batch inbox.
 enum ConfigType {
     SET_GAS_PAYING_TOKEN,
     ADD_DEPENDENCY,
-    REMOVE_DEPENDENCY
+    REMOVE_DEPENDENCY,
+    SET_BATCH_INBOX
 }
 
 /// @custom:proxied
@@ -65,6 +68,8 @@ contract L1BlockInterop is L1Block {
             _addDependency(_value);
         } else if (_type == ConfigType.REMOVE_DEPENDENCY) {
             _removeDependency(_value);
+        } else if (_type == ConfigType.SET_BATCH_INBOX) {
+            _setBatchInbox(_value);
         }
     }
 
@@ -101,4 +106,11 @@ contract L1BlockInterop is L1Block {
 
         emit DependencyRemoved(chainId);
     }
+
+    /// @notice Internal method to set the batch inbox address.
+    /// @param _value The encoded value with which to set the batch inbox address.
+    function _setBatchInbox(bytes calldata _value) internal {
+        uint256 batchInbox = StaticConfig.decodeSetBatchInbox(_value);
+        BatchInbox.set(batchInbox);
+    }
 }

packages/contracts-bedrock/src/libraries/BatchInbox.sol

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import { Storage } from "src/libraries/Storage.sol";
+
+/// @title BatchInbox
+/// @notice Handles reading and writing the batch inbox address to storage.
+///         To be used in any place where batch inbox address is read or
+///         written to state. If multiple contracts use this library, the
+///         values in storage should be kept in sync between them.
+library BatchInbox {
+    /// @notice Storage slot that the batch inbox address is stored at.
+    bytes32 public constant BATCH_INBOX_SLOT = bytes32(uint256(keccak256("opstack.batchinbox")) - 1);
+
+    /// @notice Writes the batch inbox address to the magic storage slot.
+    function set(address _batchInbox) internal {
+        Storage.setAddress(BATCH_INBOX_SLOT, _batchInbox);
+    }
+
+    /// @notice Reads the batch inbox address from the magic storage slot.
+    function get() internal view returns (address) {
+        return Storage.getAddress(BATCH_INBOX_SLOT);
+    }
+}

packages/contracts-bedrock/src/libraries/StaticConfig.sol

@@ -57,4 +57,18 @@ library StaticConfig {
     function decodeRemoveDependency(bytes memory _data) internal pure returns (uint256) {
         return abi.decode(_data, (uint256));
     }
+
+    /// @notice Encodes the static configuration data for setting a batch inbox.
+    /// @param _batchInbox Address of the batch inbox.
+    /// @return Encoded static configuration data.
+    function encodeSetBatchInbox(address _batchInbox) internal pure returns (bytes memory) {
+        return abi.encode(_batchInbox);
+    }
+
+    /// @notice Decodes the static configuration data for setting a batch inbox.
+    /// @param _data Encoded static configuration data.
+    /// @return Decoded Address of the batch inbox.
+    function decodeSetBatchInbox(bytes memory _data) internal pure returns (address) {
+        return abi.decode(_data, (address));
+    }
 }