下载geth，创建genesis.json

{
    "config": {
        "chainId": 8888, //自行修改
        "homesteadBlock": 0,
        "daoForkBlock": 0,
        "daoForkSupport": true,
        "eip150Block": 0,
        "eip155Block": 0,
        "eip158Block": 0,
        "byzantiumBlock": 0,
        "constantinopleBlock": 0,
        "petersburgBlock": 0,
        "ethash": {}
    },
    "nonce": "0x42",
    "timestamp": "0x0",
    "extraData": "0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fa",
    "gasLimit": "0xffffffff",
    "difficulty": "0x700000",//难度，越大挖矿越慢
    "alloc": {
        "093f59f1d91017d30d8c2caa78feb5beb0d2cfaf": {
            "balance": "0xffffffffffffffff"
        },
        "ddf7202cbe0aaed1c2d5c4ef05e386501a054406": {
            "balance": "0xffffffffffffffff"
        }
    }
}

因为要分析源码，所以不是像网上命令行执行，而是使用goland debug

参数
--datadir "/Users/zhangnan/Downloads/self_eth/" init "/Users/zhangnan/Downloads/geth/genesis.json"

初始化
func initGenesis(ctx *cli.Context) error {
    // Make sure we have a valid genesis JSON
    genesisPath := ctx.Args().First()
    if len(genesisPath) == 0 {
        utils.Fatalf("Must supply path to genesis JSON file")
    }
    file, err := os.Open(genesisPath)
    if err != nil {
        utils.Fatalf("Failed to read genesis file: %v", err)
    }
    defer file.Close()

    genesis := new(core.Genesis)
    if err := json.NewDecoder(file).Decode(genesis); err != nil {
        utils.Fatalf("invalid genesis file: %v", err)
    }
//以上是读初始化文件，下面开始第一个重要步骤，配置config
    // Open and initialise both full and light databases
    stack, _ := makeConfigNode(ctx)
    defer stack.Close()

    for _, name := range []string{"chaindata", "lightchaindata"} {
        chaindb, err := stack.OpenDatabase(name, 0, 0, "", false)
        if err != nil {
            utils.Fatalf("Failed to open database: %v", err)
        }
        _, hash, err := core.SetupGenesisBlock(chaindb, genesis)
        if err != nil {
            utils.Fatalf("Failed to write genesis block: %v", err)
        }
        chaindb.Close()
        log.Info("Successfully wrote genesis state", "database", name, "hash", hash)
    }
    return nil
}