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/geth/genesis_test.go

@@ -41,7 +41,9 @@ var customGenesisTests = []struct {
 			"mixhash"    : "0x0000000000000000000000000000000000000000000000000000000000000000",
 			"parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
 			"timestamp"  : "0x00",
-			"config"     : {}
+			"config"     : {
+				"terminalTotalDifficultyPassed": true
+			}
 		}`,
 		query:  "eth.getBlock(0).nonce",
 		result: "0x0000000000001338",
@@ -59,9 +61,10 @@ var customGenesisTests = []struct {
 			"parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
 			"timestamp"  : "0x00",
 			"config"     : {
-				"homesteadBlock" : 42,
-				"daoForkBlock"   : 141,
-				"daoForkSupport" : true
+				"homesteadBlock"                : 42,
+				"daoForkBlock"                  : 141,
+				"daoForkSupport"                : true,
+				"terminalTotalDifficultyPassed" : true
 			}
 		}`,
 		query:  "eth.getBlock(0).nonce",
@@ -111,8 +114,10 @@ func TestCustomBackend(t *testing.T) {
 			"mixhash"    : "0x0000000000000000000000000000000000000000000000000000000000000000",
 			"parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
 			"timestamp"  : "0x00",
-			"config"     : {}
-	}`
+			"config"     : {
+				"terminalTotalDifficultyPassed": true
+			}
+		}`
 	type backendTest struct {
 		initArgs   []string
 		initExpect string

cmd/geth/main.go

@@ -66,14 +66,6 @@ var (
 		utils.SmartCardDaemonPathFlag,
 		utils.OverrideCancun,
 		utils.EnablePersonal,
-		utils.EthashCacheDirFlag,
-		utils.EthashCachesInMemoryFlag,
-		utils.EthashCachesOnDiskFlag,
-		utils.EthashCachesLockMmapFlag,
-		utils.EthashDatasetDirFlag,
-		utils.EthashDatasetsInMemoryFlag,
-		utils.EthashDatasetsOnDiskFlag,
-		utils.EthashDatasetsLockMmapFlag,
 		utils.TxPoolLocalsFlag,
 		utils.TxPoolNoLocalsFlag,
 		utils.TxPoolJournalFlag,
@@ -120,14 +112,11 @@ var (
 		utils.MaxPeersFlag,
 		utils.MaxPendingPeersFlag,
 		utils.MiningEnabledFlag,
-		utils.MinerThreadsFlag,
-		utils.MinerNotifyFlag,
 		utils.MinerGasLimitFlag,
 		utils.MinerGasPriceFlag,
 		utils.MinerEtherbaseFlag,
 		utils.MinerExtraDataFlag,
 		utils.MinerRecommitIntervalFlag,
-		utils.MinerNoVerifyFlag,
 		utils.MinerNewPayloadTimeout,
 		utils.NATFlag,
 		utils.NoDiscoverFlag,
@@ -142,13 +131,11 @@ var (
 		utils.VMEnableDebugFlag,
 		utils.NetworkIdFlag,
 		utils.EthStatsURLFlag,
-		utils.FakePoWFlag,
 		utils.NoCompactionFlag,
 		utils.GpoBlocksFlag,
 		utils.GpoPercentileFlag,
 		utils.GpoMaxGasPriceFlag,
 		utils.GpoIgnoreGasPriceFlag,
-		utils.MinerNotifyFullFlag,
 		configFileFlag,
 	}, utils.NetworkFlags, utils.DatabasePathFlags)
 
@@ -224,8 +211,6 @@ func init() {
 		attachCommand,
 		javascriptCommand,
 		// See misccmd.go:
-		makecacheCommand,
-		makedagCommand,
 		versionCommand,
 		versionCheckCommand,
 		licenseCommand,
@@ -438,9 +423,7 @@ func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend, isCon
 		// Set the gas price to the limits from the CLI and start mining
 		gasprice := flags.GlobalBig(ctx, utils.MinerGasPriceFlag.Name)
 		ethBackend.TxPool().SetGasPrice(gasprice)
-		// start mining
-		threads := ctx.Int(utils.MinerThreadsFlag.Name)
-		if err := ethBackend.StartMining(threads); err != nil {
+		if err := ethBackend.StartMining(); err != nil {
 			utils.Fatalf("Failed to start mining: %v", err)
 		}
 	}

cmd/geth/misccmd.go

@@ -20,11 +20,8 @@ import (
 	"fmt"
 	"os"
 	"runtime"
-	"strconv"
 	"strings"
 
-	"github.com/ethereum/go-ethereum/cmd/utils"
-	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/internal/version"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/urfave/cli/v2"
@@ -41,30 +38,6 @@ var (
 		Usage: "Version to check",
 		Value: version.ClientName(clientIdentifier),
 	}
-	makecacheCommand = &cli.Command{
-		Action:    makecache,
-		Name:      "makecache",
-		Usage:     "Generate ethash verification cache (for testing)",
-		ArgsUsage: "<blockNum> <outputDir>",
-		Description: `
-The makecache command generates an ethash cache in <outputDir>.
-
-This command exists to support the system testing project.
-Regular users do not need to execute it.
-`,
-	}
-	makedagCommand = &cli.Command{
-		Action:    makedag,
-		Name:      "makedag",
-		Usage:     "Generate ethash mining DAG (for testing)",
-		ArgsUsage: "<blockNum> <outputDir>",
-		Description: `
-The makedag command generates an ethash DAG in <outputDir>.
-
-This command exists to support the system testing project.
-Regular users do not need to execute it.
-`,
-	}
 	versionCommand = &cli.Command{
 		Action:    printVersion,
 		Name:      "version",
@@ -96,36 +69,6 @@ and displays information about any security vulnerabilities that affect the curr
 	}
 )
 
-// makecache generates an ethash verification cache into the provided folder.
-func makecache(ctx *cli.Context) error {
-	args := ctx.Args().Slice()
-	if len(args) != 2 {
-		utils.Fatalf(`Usage: geth makecache <block number> <outputdir>`)
-	}
-	block, err := strconv.ParseUint(args[0], 0, 64)
-	if err != nil {
-		utils.Fatalf("Invalid block number: %v", err)
-	}
-	ethash.MakeCache(block, args[1])
-
-	return nil
-}
-
-// makedag generates an ethash mining DAG into the provided folder.
-func makedag(ctx *cli.Context) error {
-	args := ctx.Args().Slice()
-	if len(args) != 2 {
-		utils.Fatalf(`Usage: geth makedag <block number> <outputdir>`)
-	}
-	block, err := strconv.ParseUint(args[0], 0, 64)
-	if err != nil {
-		utils.Fatalf("Invalid block number: %v", err)
-	}
-	ethash.MakeDataset(block, args[1])
-
-	return nil
-}
-
 func printVersion(ctx *cli.Context) error {
 	git, _ := version.VCS()