Set chain config

migration/README.md

@@ -128,3 +128,23 @@ On the parent chain you need to call the `perform()` function on the EspressoArb
 ```
 cast send $CHILD_CHAIN_UPGRADE_EXECUTOR_ADDRESS "execute(address, bytes)" $ARBOS_UPGRADE_ACTION $(cast calldata "perform()") --rpc-url $CHILD_CHAIN_RPC_URL --private-key $PRIVATE_KEY
 ```
+
+## Enabling Espresso STF behavior
+
+To enable the behavior in the STF that provides compatibility with the Espresso network, you must send a request (via cast) to the `ArbOwner` precompile to update your networks chain config.
+
+There is an example chain config json file in the same directory as this README to show which fields need to be added to the standard Arbitrum chain config.
+
+Ensure that values other than the new Espresso field are the same values as they are in your current chain config. It is **incredibly important** that the node with espresso compatible code is loaded with a chain config that contains the `EnableEspresso` flag inside the arbitrum chain parameters. If the config doesn't contain this flag, attempting to set the chain config in the following manner will cause the delegated call from the `UpgradeExecutor` to revert.
+
+The request to the ArbOwner precompile must come from an address designated as a chain owner. Typically this is the `UpgradeExecutor`.
+
+The following command uses cast and the `UpgradeExecutor` to send the new chain config to the network.
+
+Note: The address 0x0000000000000000000000000000000000000070 is the hard-coded address of the ArbOwner precompile on arbitrum derived chains.
+
+
+```
+cast send $CHILD_CHAIN_UPGRADE_EXECUTOR_ADDRESS "execute(address, bytes)" 0x0000000000000000000000000000000000000070 $(cast calldata "setChainConfig(string)" "$(cat /chain/config/location)") --rpc-url $CHILD_CHAIN_RPC_URL --private-key $PRIVATE_KEY
+```
+

migration/example-chain-config.json

@@ -0,0 +1,29 @@
+    {
+    "chainId":412346,
+    "homesteadBlock":0,
+    "daoForkSupport":true,
+    "eip150Block":0,
+    "eip150Hash":"0x0000000000000000000000000000000000000000000000000000000000000000",
+    "eip155Block":0,
+    "eip158Block":0,
+    "byzantiumBlock":0,
+    "constantinopleBlock":0,
+    "petersburgBlock":0,
+    "istanbulBlock":0,
+    "muirGlacierBlock":0,
+    "berlinBlock":0,
+    "londonBlock":0,
+    "clique":{
+        "period":0,
+        "epoch":0
+    },
+    "arbitrum":{
+        "EnableArbOS":true,
+        "AllowDebugPrecompiles":true,
+        "DataAvailabilityCommittee":false,
+        "InitialArbOSVersion":30,
+        "InitialChainOwner":"0x0000000000000000000000000000000000000000",
+        "GenesisBlockNum":0,
+        "EnableEspresso":true
+    }
+}