devnet: Use later L2 timestamp for network

ops-bedrock/devnet-up.sh

@@ -60,7 +60,7 @@ mkdir -p ./.devnet
 if [ ! -f ./.devnet/rollup.json ]; then
     GENESIS_TIMESTAMP=$(date +%s | xargs printf "0x%x")
 else
-    GENESIS_TIMESTAMP=$(jq '.genesis.l2_time' < .devnet/rollup.json)
+    GENESIS_TIMESTAMP=$(jq '.timestamp' < .devnet/genesis-l1.json)
 fi
 
 # Regenerate the L1 genesis file if necessary. The existence of the genesis

packages/contracts-bedrock/tasks/genesis-l2.ts

@@ -52,6 +52,7 @@ task('genesis-l2', 'create a genesis config')
     'The file to write the output JSON to',
     'genesis.json'
   )
+  .addOptionalParam('l1RpcUrl', 'The L1 RPC URL', 'http://127.0.0.1:8545')
   .setAction(async (args, hre) => {
     const {
       computeStorageSlots,
@@ -60,6 +61,8 @@ task('genesis-l2', 'create a genesis config')
 
     const { deployConfig } = hre
 
+    const l1 = new ethers.providers.StaticJsonRpcProvider(args.l1RpcUrl)
+
     // Use the addresses of the proxies here instead of the implementations
     // Be backwards compatible
     let ProxyL1CrossDomainMessenger = await hre.deployments.getOrNull(
@@ -256,6 +259,9 @@ task('genesis-l2', 'create a genesis config')
       }
     }
 
+    const portal = await hre.deployments.get('OptimismPortalProxy')
+    const l1StartingBlock = await l1.getBlock(portal.receipt.blockHash)
+
     const genesis: OptimismGenesis = {
       config: {
         chainId: deployConfig.genesisBlockChainid,
@@ -279,9 +285,7 @@ task('genesis-l2', 'create a genesis config')
       },
       nonce: '0x1234',
       difficulty: '0x1',
-      timestamp: ethers.BigNumber.from(
-        deployConfig.startingTimestamp
-      ).toHexString(),
+      timestamp: ethers.BigNumber.from(l1StartingBlock.timestamp).toHexString(),
       gasLimit: deployConfig.genesisBlockGasLimit,
       extraData: deployConfig.genesisBlockExtradata,
       optimism: {

packages/contracts-bedrock/tasks/rollup-config.ts

@@ -21,6 +21,7 @@ task('rollup-config', 'create a genesis config')
     const l2Genesis = await l2.getBlock('earliest')
 
     const portal = await hre.deployments.get('OptimismPortalProxy')
+    const l1StartingBlock = await l1.getBlock(portal.receipt.blockHash)
 
     const config: OpNodeConfig = {
       genesis: {
@@ -32,7 +33,7 @@ task('rollup-config', 'create a genesis config')
           hash: l2Genesis.hash,
           number: 0,
         },
-        l2_time: deployConfig.startingTimestamp,
+        l2_time: l1StartingBlock.timestamp,
       },
       block_time: deployConfig.l2BlockTime,
       max_sequencer_drift: deployConfig.maxSequencerDrift,