all: remove ethash pow, only retain shims needed for consensus and tests (#27178)

* all: remove ethash pow, only retain shims needed for consensus and tests

* all: thank you linter

* all: disallow launching Geth in legacy PoW mode

* cmd/env/internal/t8ntool: remove dangling ethash flag

cmd/evm/internal/t8ntool/block.go

@@ -28,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/consensus/clique"
-	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
@@ -74,11 +73,9 @@ type bbInput struct {
 	Withdrawals []*types.Withdrawal `json:"withdrawals,omitempty"`
 	Clique      *cliqueInput        `json:"clique,omitempty"`
 
-	Ethash    bool                 `json:"-"`
-	EthashDir string               `json:"-"`
-	PowMode   ethash.Mode          `json:"-"`
-	Txs       []*types.Transaction `json:"-"`
-	Ommers    []*types.Header      `json:"-"`
+	Ethash bool                 `json:"-"`
+	Txs    []*types.Transaction `json:"-"`
+	Ommers []*types.Header      `json:"-"`
 }
 
 type cliqueInput struct {
@@ -162,8 +159,6 @@ func (i *bbInput) ToBlock() *types.Block {
 // SealBlock seals the given block using the configured engine.
 func (i *bbInput) SealBlock(block *types.Block) (*types.Block, error) {
 	switch {
-	case i.Ethash:
-		return i.sealEthash(block)
 	case i.Clique != nil:
 		return i.sealClique(block)
 	default:
@@ -171,33 +166,6 @@ func (i *bbInput) SealBlock(block *types.Block) (*types.Block, error) {
 	}
 }
 
-// sealEthash seals the given block using ethash.
-func (i *bbInput) sealEthash(block *types.Block) (*types.Block, error) {
-	if i.Header.Nonce != nil {
-		return nil, NewError(ErrorConfig, fmt.Errorf("sealing with ethash will overwrite provided nonce"))
-	}
-	ethashConfig := ethash.Config{
-		PowMode:        i.PowMode,
-		DatasetDir:     i.EthashDir,
-		CacheDir:       i.EthashDir,
-		DatasetsInMem:  1,
-		DatasetsOnDisk: 2,
-		CachesInMem:    2,
-		CachesOnDisk:   3,
-	}
-	engine := ethash.New(ethashConfig, nil, true)
-	defer engine.Close()
-	// Use a buffered chan for results.
-	// If the testmode is used, the sealer will return quickly, and complain
-	// "Sealing result is not read by miner" if it cannot write the result.
-	results := make(chan *types.Block, 1)
-	if err := engine.Seal(nil, block, results, nil); err != nil {
-		panic(fmt.Sprintf("failed to seal block: %v", err))
-	}
-	found := <-results
-	return block.WithSeal(found.Header()), nil
-}
-
 // sealClique seals the given block using clique.
 func (i *bbInput) sealClique(block *types.Block) (*types.Block, error) {
 	// If any clique value overwrites an explicit header value, fail
@@ -267,28 +235,8 @@ func readInput(ctx *cli.Context) (*bbInput, error) {
 		withdrawalsStr = ctx.String(InputWithdrawalsFlag.Name)
 		txsStr         = ctx.String(InputTxsRlpFlag.Name)
 		cliqueStr      = ctx.String(SealCliqueFlag.Name)
-		ethashOn       = ctx.Bool(SealEthashFlag.Name)
-		ethashDir      = ctx.String(SealEthashDirFlag.Name)
-		ethashMode     = ctx.String(SealEthashModeFlag.Name)
 		inputData      = &bbInput{}
 	)
-	if ethashOn && cliqueStr != "" {
-		return nil, NewError(ErrorConfig, fmt.Errorf("both ethash and clique sealing specified, only one may be chosen"))
-	}
-	if ethashOn {
-		inputData.Ethash = ethashOn
-		inputData.EthashDir = ethashDir
-		switch ethashMode {
-		case "normal":
-			inputData.PowMode = ethash.ModeNormal
-		case "test":
-			inputData.PowMode = ethash.ModeTest
-		case "fake":
-			inputData.PowMode = ethash.ModeFake
-		default:
-			return nil, NewError(ErrorConfig, fmt.Errorf("unknown pow mode: %s, supported modes: test, fake, normal", ethashMode))
-		}
-	}
 	if headerStr == stdinSelector || ommersStr == stdinSelector || txsStr == stdinSelector || cliqueStr == stdinSelector {
 		decoder := json.NewDecoder(os.Stdin)
 		if err := decoder.Decode(inputData); err != nil {

cmd/evm/internal/t8ntool/flags.go

@@ -125,19 +125,6 @@ var (
 		Name:  "seal.clique",
 		Usage: "Seal block with Clique. `stdin` or file name of where to find the Clique sealing data.",
 	}
-	SealEthashFlag = &cli.BoolFlag{
-		Name:  "seal.ethash",
-		Usage: "Seal block with ethash.",
-	}
-	SealEthashDirFlag = &cli.StringFlag{
-		Name:  "seal.ethash.dir",
-		Usage: "Path to ethash DAG. If none exists, a new DAG will be generated.",
-	}
-	SealEthashModeFlag = &cli.StringFlag{
-		Name:  "seal.ethash.mode",
-		Usage: "Defines the type and amount of PoW verification an ethash engine makes.",
-		Value: "normal",
-	}
 	RewardFlag = &cli.Int64Flag{
 		Name:  "state.reward",
 		Usage: "Mining reward. Set to -1 to disable",