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core: assign default difficulty to zero for chain without ethash #31067

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Merged
fjl merged 2 commits into from
Feb 4, 2025
Merged

core: assign default difficulty to zero for chain without ethash #31067

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e65c08f
core: assign default difficulty to zero for chain without ethash
fjl Jan 23, 2025
9e31c48
core: fix genesis test by adding ethash config
lightclient Feb 4, 2025
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8 changes: 6 additions & 2 deletions core/genesis.go
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Original file line number Diff line number Diff line change
Expand Up @@ -459,8 +459,12 @@ func (g *Genesis) toBlockWithRoot(root common.Hash) *types.Block {
if g.GasLimit == 0 {
head.GasLimit = params.GenesisGasLimit
}
if g.Difficulty == nil && g.Mixhash == (common.Hash{}) {
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@rjl493456442 rjl493456442 Jan 23, 2025

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QQ, Why the g.MixHash == (common.Hash{}) is a condition for setting the genesis difficulty?

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@fjl fjl Jan 23, 2025

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I don't get it either. This code is very old.

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@fjl fjl Jan 23, 2025

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It was added in the PR that also added the RANDOM opcode. https://github.com/ethereum/go-ethereum/pull/24141/files#diff-1272116434e5549f278a940767af52ed2d1abc91c44fa04ec48d8835a3774036

@MariusVanDerWijden might know more.

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@fjl fjl Jan 23, 2025 •
edited
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I think it might be related with the idea of how the header MixDigest is used. After the merge, this field was repurposed for the random value. What @MariusVanDerWijden may have been thinking is: "if Mixhash is set in genesis, it means the genesis block is supposed to have a random value (signaling the merge), and thus difficulty will be set to zero."

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@MariusVanDerWijden MariusVanDerWijden Jan 30, 2025

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Yes I think that was it. It fixed a test case from the testing team if I remember correctly

head.Difficulty = params.GenesisDifficulty
if g.Difficulty == nil {
if g.Config != nil && g.Config.Ethash == nil {
head.Difficulty = big.NewInt(0)
} else if g.Mixhash == (common.Hash{}) {
head.Difficulty = params.GenesisDifficulty
}
}
if g.Config != nil && g.Config.IsLondon(common.Big0) {
if g.BaseFee != nil {
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4 changes: 2 additions & 2 deletions core/genesis_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -44,14 +44,14 @@ func testSetupGenesis(t *testing.T, scheme string) {
var (
customghash = common.HexToHash("0x89c99d90b79719238d2645c7642f2c9295246e80775b38cfd162b696817fbd50")
customg = Genesis{
Config: &params.ChainConfig{HomesteadBlock: big.NewInt(3)},
Config: &params.ChainConfig{HomesteadBlock: big.NewInt(3), Ethash: &params.EthashConfig{}},
Alloc: types.GenesisAlloc{
{1}: {Balance: big.NewInt(1), Storage: map[common.Hash]common.Hash{{1}: {1}}},
},
}
oldcustomg = customg
)
oldcustomg.Config = &params.ChainConfig{HomesteadBlock: big.NewInt(2)}
oldcustomg.Config = &params.ChainConfig{HomesteadBlock: big.NewInt(2), Ethash: &params.EthashConfig{}}

tests := []struct {
name string
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