Override TTD sometimes doesn't work

[MariusVanDerWijden]

No description provided.

[prestonvanloon]

We experienced this issue today when running with the following flags

            - '--datadir=/data'
            - '--sepolia'
            - '--http'
            - '--http.api=engine,net,eth'
            - '--http.addr=0.0.0.0'
            - '--http.vhosts='
            - '--http.port=8545'
            - '--authrpc.addr=0.0.0.0'
            - '--authrpc.vhosts='
            - '--authrpc.port=8551'
            - '--authrpc.jwtsecret=/secret/authrpc/jwt.hex'
            - '--ws'
            - '--ws.api=net,eth,engine'
            - '--override.terminaltotaldifficulty=100000000000000000000000'

Geth version 1.10.18

[leolara]

@MariusVanDerWijden @prestonvanloon I experienced this, when the datadir is empty, after the genesis block has been inserted into the database, if you restart then the terminal difficulty override is used.

I have trace back the problem to here:

https://github.com/ethereum/go-ethereum/blob/master/core/genesis.go#L240-L254

	stored := rawdb.ReadCanonicalHash(db, 0)
	if (stored == common.Hash{}) {
		if genesis == nil {
			log.Info("Writing default main-net genesis block")
			genesis = DefaultGenesisBlock()
		} else {
			log.Info("Writing custom genesis block")
		}
		block, err := genesis.Commit(db)
		if err != nil {
			return genesis.Config, common.Hash{}, err
		}
		return genesis.Config, block.Hash(), nil
	}

if it does not find the genesis block in the DB, it stores it, and then returns its default config, without going through the lines bellow:

https://github.com/ethereum/go-ethereum/blob/master/core/genesis.go#L285-L287

	if overrideTerminalTotalDifficulty != nil {
		newcfg.TerminalTotalDifficulty = overrideTerminalTotalDifficulty
	}