From 2f16843c5ac8114d682a2a43491d31e8c6c29b14 Mon Sep 17 00:00:00 2001
From: lightclient <lightclient@protonmail.com>
Date: Mon, 3 Feb 2025 16:10:34 -0700
Subject: [PATCH] core: default genesis difficulty to zero for merged chains

---
 core/genesis.go | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/core/genesis.go b/core/genesis.go
index b579e33c77..fca3b36f97 100644
--- a/core/genesis.go
+++ b/core/genesis.go
@@ -35,6 +35,7 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/params/forks"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 	"github.com/ethereum/go-ethereum/triedb"
@@ -460,7 +461,13 @@ func (g *Genesis) toBlockWithRoot(root common.Hash) *types.Block {
 		head.GasLimit = params.GenesisGasLimit
 	}
 	if g.Difficulty == nil && g.Mixhash == (common.Hash{}) {
-		head.Difficulty = params.GenesisDifficulty
+		if g.Config.LatestFork(g.Timestamp) >= forks.Shanghai {
+			// If chain is merged at genesis, set difficulty to zero.
+			head.Difficulty = big.NewInt(0)
+		} else {
+			// In case chain is not merged at genesis, set default genesis difficulty.
+			head.Difficulty = params.GenesisDifficulty
+		}
 	}
 	if g.Config != nil && g.Config.IsLondon(common.Big0) {
 		if g.BaseFee != nil {