specs,op-node: handle when Ecotone is active on L2 before L1 (#9073)

op-e2e/actions/ecotone_fork_test.go

@@ -175,3 +175,32 @@ func TestEcotoneNetworkUpgradeTransactions(gt *testing.T) {
 	expectedL1Fee = expectedL1Fee.Div(expectedL1Fee, big.NewInt(16e6))
 	require.Equal(t, expectedL1Fee, cost, "expecting cost based on regular base fee scalar alone")
 }
+
+// TestEcotoneBeforeL1 tests that the L2 Ecotone fork can activate before L1 Dencun does
+func TestEcotoneBeforeL1(gt *testing.T) {
+	t := NewDefaultTesting(gt)
+	dp := e2eutils.MakeDeployParams(t, defaultRollupTestParams)
+	offset := hexutil.Uint64(0)
+	farOffset := hexutil.Uint64(10000)
+	dp.DeployConfig.L2GenesisRegolithTimeOffset = &offset
+	dp.DeployConfig.L1CancunTimeOffset = &farOffset // L1 Dencun will not be active at genesis
+	dp.DeployConfig.L2GenesisCanyonTimeOffset = &offset
+	dp.DeployConfig.L2GenesisDeltaTimeOffset = &offset
+	dp.DeployConfig.L2GenesisEcotoneTimeOffset = &offset
+
+	sd := e2eutils.Setup(t, dp, defaultAlloc)
+	log := testlog.Logger(t, log.LvlDebug)
+	_, _, _, sequencer, engine, verifier, _, _ := setupReorgTestActors(t, dp, sd, log)
+
+	// start op-nodes
+	sequencer.ActL2PipelineFull(t)
+	verifier.ActL2PipelineFull(t)
+
+	// Genesis block has ecotone properties
+	verifyEcotoneBlock(gt, engine.l2Chain.CurrentBlock())
+
+	// Blocks post fork have Ecotone properties
+	sequencer.ActL2StartBlock(t)
+	sequencer.ActL2EndBlock(t)
+	verifyEcotoneBlock(gt, engine.l2Chain.CurrentBlock())
+}

op-node/rollup/derive/attributes.go

@@ -126,8 +126,8 @@ func (ba *FetchingAttributesBuilder) PreparePayloadAttributes(ctx context.Contex
 	var parentBeaconRoot *common.Hash
 	if ba.rollupCfg.IsEcotone(nextL2Time) {
 		parentBeaconRoot = l1Info.ParentBeaconRoot()
-		if parentBeaconRoot == nil {
-			return nil, NewCriticalError(fmt.Errorf("cannot build Ecotone (L2 Dencun) block without L1 Dencun info, at L2 timestamp %d", nextL2Time))
+		if parentBeaconRoot == nil { // default to zero hash if there is no beacon-block-root available
+			parentBeaconRoot = new(common.Hash)
 		}
 	}
 

specs/exec-engine.md

@@ -278,8 +278,9 @@ PayloadAttributesV3: {
 The requirements of this object are the same as extended [`PayloadAttributesV2`][#extended-payloadattributesv2] with
 the addition of `parentBeaconBlockRoot` which is the parent beacon block root from the L1 origin block of the L2 block.
 
-`parentBeaconBlockRoot` must be nil for Bedrock/Canyon/Delta payloads, but must be set to the L1
-origin `parentBeaconBlockRoot`.
+The `parentBeaconBlockRoot` must be nil for Bedrock/Canyon/Delta payloads.
+Starting at Ecotone, the `parentBeaconBlockRoot` must be set to the L1 origin `parentBeaconBlockRoot`,
+or a zero `bytes32` if the Dencun functionality with `parentBeaconBlockRoot` is not active on L1.
 
 ### `engine_newPayloadV2`