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

core/block_validator_test.go

@@ -55,10 +55,10 @@ func TestHeaderVerification(t *testing.T) {
 
 			if valid {
 				engine := ethash.NewFaker()
-				_, results = engine.VerifyHeaders(chain, []*types.Header{headers[i]}, []bool{true})
+				_, results = engine.VerifyHeaders(chain, []*types.Header{headers[i]})
 			} else {
 				engine := ethash.NewFakeFailer(headers[i].Number.Uint64())
-				_, results = engine.VerifyHeaders(chain, []*types.Header{headers[i]}, []bool{true})
+				_, results = engine.VerifyHeaders(chain, []*types.Header{headers[i]})
 			}
 			// Wait for the verification result
 			select {
@@ -164,7 +164,7 @@ func testHeaderVerificationForMerging(t *testing.T, isClique bool) {
 
 	// Verify the blocks before the merging
 	for i := 0; i < len(preBlocks); i++ {
-		_, results := engine.VerifyHeaders(chain, []*types.Header{preHeaders[i]}, []bool{true})
+		_, results := engine.VerifyHeaders(chain, []*types.Header{preHeaders[i]})
 		// Wait for the verification result
 		select {
 		case result := <-results:
@@ -189,7 +189,7 @@ func testHeaderVerificationForMerging(t *testing.T, isClique bool) {
 
 	// Verify the blocks after the merging
 	for i := 0; i < len(postBlocks); i++ {
-		_, results := engine.VerifyHeaders(chain, []*types.Header{postHeaders[i]}, []bool{true})
+		_, results := engine.VerifyHeaders(chain, []*types.Header{postHeaders[i]})
 		// Wait for the verification result
 		select {
 		case result := <-results:
@@ -209,19 +209,14 @@ func testHeaderVerificationForMerging(t *testing.T, isClique bool) {
 	}
 
 	// Verify the blocks with pre-merge blocks and post-merge blocks
-	var (
-		headers []*types.Header
-		seals   []bool
-	)
+	var headers []*types.Header
 	for _, block := range preBlocks {
 		headers = append(headers, block.Header())
-		seals = append(seals, true)
 	}
 	for _, block := range postBlocks {
 		headers = append(headers, block.Header())
-		seals = append(seals, true)
 	}
-	_, results := engine.VerifyHeaders(chain, headers, seals)
+	_, results := engine.VerifyHeaders(chain, headers)
 	for i := 0; i < len(headers); i++ {
 		select {
 		case result := <-results:
@@ -252,11 +247,8 @@ func testHeaderConcurrentVerification(t *testing.T, threads int) {
 		_, blocks, _ = GenerateChainWithGenesis(gspec, ethash.NewFaker(), 8, nil)
 	)
 	headers := make([]*types.Header, len(blocks))
-	seals := make([]bool, len(blocks))
-
 	for i, block := range blocks {
 		headers[i] = block.Header()
-		seals[i] = true
 	}
 	// Set the number of threads to verify on
 	old := runtime.GOMAXPROCS(threads)
@@ -269,11 +261,11 @@ func testHeaderConcurrentVerification(t *testing.T, threads int) {
 
 		if valid {
 			chain, _ := NewBlockChain(rawdb.NewMemoryDatabase(), nil, gspec, nil, ethash.NewFaker(), vm.Config{}, nil, nil)
-			_, results = chain.engine.VerifyHeaders(chain, headers, seals)
+			_, results = chain.engine.VerifyHeaders(chain, headers)
 			chain.Stop()
 		} else {
 			chain, _ := NewBlockChain(rawdb.NewMemoryDatabase(), nil, gspec, nil, ethash.NewFakeFailer(uint64(len(headers)-1)), vm.Config{}, nil, nil)
-			_, results = chain.engine.VerifyHeaders(chain, headers, seals)
+			_, results = chain.engine.VerifyHeaders(chain, headers)
 			chain.Stop()
 		}
 		// Wait for all the verification results
@@ -322,11 +314,8 @@ func testHeaderConcurrentAbortion(t *testing.T, threads int) {
 		_, blocks, _ = GenerateChainWithGenesis(gspec, ethash.NewFaker(), 1024, nil)
 	)
 	headers := make([]*types.Header, len(blocks))
-	seals := make([]bool, len(blocks))
-
 	for i, block := range blocks {
 		headers[i] = block.Header()
-		seals[i] = true
 	}
 	// Set the number of threads to verify on
 	old := runtime.GOMAXPROCS(threads)
@@ -336,7 +325,7 @@ func testHeaderConcurrentAbortion(t *testing.T, threads int) {
 	chain, _ := NewBlockChain(rawdb.NewMemoryDatabase(), nil, gspec, nil, ethash.NewFakeDelayer(time.Millisecond), vm.Config{}, nil, nil)
 	defer chain.Stop()
 
-	abort, results := chain.engine.VerifyHeaders(chain, headers, seals)
+	abort, results := chain.engine.VerifyHeaders(chain, headers)
 	close(abort)
 
 	// Deplete the results channel

core/blockchain.go

@@ -365,7 +365,7 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 	// The first thing the node will do is reconstruct the verification data for
 	// the head block (ethash cache or clique voting snapshot). Might as well do
 	// it in advance.
-	bc.engine.VerifyHeader(bc, bc.CurrentHeader(), true)
+	bc.engine.VerifyHeader(bc, bc.CurrentHeader())
 
 	// Check the current state of the block hashes and make sure that we do not have any of the bad blocks in our chain
 	for hash := range BadHashes {
@@ -1522,7 +1522,7 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 		return 0, errChainStopped
 	}
 	defer bc.chainmu.Unlock()
-	return bc.insertChain(chain, true, true)
+	return bc.insertChain(chain, true)
 }
 
 // insertChain is the internal implementation of InsertChain, which assumes that
@@ -1533,7 +1533,7 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 // racey behaviour. If a sidechain import is in progress, and the historic state
 // is imported, but then new canon-head is added before the actual sidechain
 // completes, then the historic state could be pruned again
-func (bc *BlockChain) insertChain(chain types.Blocks, verifySeals, setHead bool) (int, error) {
+func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool) (int, error) {
 	// If the chain is terminating, don't even bother starting up.
 	if bc.insertStopped() {
 		return 0, nil
@@ -1554,13 +1554,10 @@ func (bc *BlockChain) insertChain(chain types.Blocks, verifySeals, setHead bool)
 	}()
 	// Start the parallel header verifier
 	headers := make([]*types.Header, len(chain))
-	seals := make([]bool, len(chain))
-
 	for i, block := range chain {
 		headers[i] = block.Header()
-		seals[i] = verifySeals
 	}
-	abort, results := bc.engine.VerifyHeaders(bc, headers, seals)
+	abort, results := bc.engine.VerifyHeaders(bc, headers)
 	defer close(abort)
 
 	// Peek the error for the first block to decide the directing import logic
@@ -1981,7 +1978,7 @@ func (bc *BlockChain) insertSideChain(block *types.Block, it *insertIterator) (i
 		// memory here.
 		if len(blocks) >= 2048 || memory > 64*1024*1024 {
 			log.Info("Importing heavy sidechain segment", "blocks", len(blocks), "start", blocks[0].NumberU64(), "end", block.NumberU64())
-			if _, err := bc.insertChain(blocks, false, true); err != nil {
+			if _, err := bc.insertChain(blocks, true); err != nil {
 				return 0, err
 			}
 			blocks, memory = blocks[:0], 0
@@ -1995,7 +1992,7 @@ func (bc *BlockChain) insertSideChain(block *types.Block, it *insertIterator) (i
 	}
 	if len(blocks) > 0 {
 		log.Info("Importing sidechain segment", "start", blocks[0].NumberU64(), "end", blocks[len(blocks)-1].NumberU64())
-		return bc.insertChain(blocks, false, true)
+		return bc.insertChain(blocks, true)
 	}
 	return 0, nil
 }
@@ -2038,7 +2035,7 @@ func (bc *BlockChain) recoverAncestors(block *types.Block) (common.Hash, error)
 		} else {
 			b = bc.GetBlock(hashes[i], numbers[i])
 		}
-		if _, err := bc.insertChain(types.Blocks{b}, false, false); err != nil {
+		if _, err := bc.insertChain(types.Blocks{b}, false); err != nil {
 			return b.ParentHash(), err
 		}
 	}
@@ -2242,7 +2239,7 @@ func (bc *BlockChain) InsertBlockWithoutSetHead(block *types.Block) error {
 	}
 	defer bc.chainmu.Unlock()
 
-	_, err := bc.insertChain(types.Blocks{block}, true, false)
+	_, err := bc.insertChain(types.Blocks{block}, false)
 	return err
 }
 
@@ -2462,17 +2459,12 @@ Receipts: %v
 // InsertHeaderChain attempts to insert the given header chain in to the local
 // chain, possibly creating a reorg. If an error is returned, it will return the
 // index number of the failing header as well an error describing what went wrong.
-//
-// The verify parameter can be used to fine tune whether nonce verification
-// should be done or not. The reason behind the optional check is because some
-// of the header retrieval mechanisms already need to verify nonces, as well as
-// because nonces can be verified sparsely, not needing to check each.
-func (bc *BlockChain) InsertHeaderChain(chain []*types.Header, checkFreq int) (int, error) {
+func (bc *BlockChain) InsertHeaderChain(chain []*types.Header) (int, error) {
 	if len(chain) == 0 {
 		return 0, nil
 	}
 	start := time.Now()
-	if i, err := bc.hc.ValidateHeaderChain(chain, checkFreq); err != nil {
+	if i, err := bc.hc.ValidateHeaderChain(chain); err != nil {
 		return i, err
 	}
 

core/blockchain_test.go

@@ -74,7 +74,7 @@ func newCanonical(engine consensus.Engine, n int, full bool) (ethdb.Database, *G
 	}
 	// Header-only chain requested
 	genDb, headers := makeHeaderChainWithGenesis(genesis, n, engine, canonicalSeed)
-	_, err := blockchain.InsertHeaderChain(headers, 1)
+	_, err := blockchain.InsertHeaderChain(headers)
 	return genDb, genesis, blockchain, err
 }
 
@@ -115,7 +115,7 @@ func testFork(t *testing.T, blockchain *BlockChain, i, n int, full bool, compara
 		}
 	} else {
 		headerChainB = makeHeaderChain(blockchain2.chainConfig, blockchain2.CurrentHeader(), n, ethash.NewFaker(), genDb, forkSeed)
-		if _, err := blockchain2.InsertHeaderChain(headerChainB, 1); err != nil {
+		if _, err := blockchain2.InsertHeaderChain(headerChainB); err != nil {
 			t.Fatalf("failed to insert forking chain: %v", err)
 		}
 	}
@@ -148,7 +148,7 @@ func testFork(t *testing.T, blockchain *BlockChain, i, n int, full bool, compara
 func testBlockChainImport(chain types.Blocks, blockchain *BlockChain) error {
 	for _, block := range chain {
 		// Try and process the block
-		err := blockchain.engine.VerifyHeader(blockchain, block.Header(), true)
+		err := blockchain.engine.VerifyHeader(blockchain, block.Header())
 		if err == nil {
 			err = blockchain.validator.ValidateBody(block)
 		}
@@ -187,7 +187,7 @@ func testBlockChainImport(chain types.Blocks, blockchain *BlockChain) error {
 func testHeaderChainImport(chain []*types.Header, blockchain *BlockChain) error {
 	for _, header := range chain {
 		// Try and validate the header
-		if err := blockchain.engine.VerifyHeader(blockchain, header, false); err != nil {
+		if err := blockchain.engine.VerifyHeader(blockchain, header); err != nil {
 			return err
 		}
 		// Manually insert the header into the database, but don't reorganise (allows subsequent testing)
@@ -252,7 +252,7 @@ func testInsertAfterMerge(t *testing.T, blockchain *BlockChain, i, n int, full b
 		}
 	} else {
 		headerChainB := makeHeaderChain(blockchain2.chainConfig, blockchain2.CurrentHeader(), n, ethash.NewFaker(), genDb, forkSeed)
-		if _, err := blockchain2.InsertHeaderChain(headerChainB, 1); err != nil {
+		if _, err := blockchain2.InsertHeaderChain(headerChainB); err != nil {
 			t.Fatalf("failed to insert forking chain: %v", err)
 		}
 		if blockchain2.CurrentHeader().Number.Uint64() != headerChainB[len(headerChainB)-1].Number.Uint64() {
@@ -549,10 +549,10 @@ func testReorg(t *testing.T, first, second []int64, td int64, full bool) {
 		for i, block := range diffBlocks {
 			diffHeaders[i] = block.Header()
 		}
-		if _, err := blockchain.InsertHeaderChain(easyHeaders, 1); err != nil {
+		if _, err := blockchain.InsertHeaderChain(easyHeaders); err != nil {
 			t.Fatalf("failed to insert easy chain: %v", err)
 		}
-		if _, err := blockchain.InsertHeaderChain(diffHeaders, 1); err != nil {
+		if _, err := blockchain.InsertHeaderChain(diffHeaders); err != nil {
 			t.Fatalf("failed to insert difficult chain: %v", err)
 		}
 	}
@@ -613,7 +613,7 @@ func testBadHashes(t *testing.T, full bool) {
 		BadHashes[headers[2].Hash()] = true
 		defer func() { delete(BadHashes, headers[2].Hash()) }()
 
-		_, err = blockchain.InsertHeaderChain(headers, 1)
+		_, err = blockchain.InsertHeaderChain(headers)
 	}
 	if !errors.Is(err, ErrBannedHash) {
 		t.Errorf("error mismatch: have: %v, want: %v", err, ErrBannedHash)
@@ -645,7 +645,7 @@ func testReorgBadHashes(t *testing.T, full bool) {
 		BadHashes[blocks[3].Header().Hash()] = true
 		defer func() { delete(BadHashes, blocks[3].Header().Hash()) }()
 	} else {
-		if _, err = blockchain.InsertHeaderChain(headers, 1); err != nil {
+		if _, err = blockchain.InsertHeaderChain(headers); err != nil {
 			t.Errorf("failed to import headers: %v", err)
 		}
 		if blockchain.CurrentHeader().Hash() != headers[3].Hash() {
@@ -711,7 +711,7 @@ func testInsertNonceError(t *testing.T, full bool) {
 
 			blockchain.engine = ethash.NewFakeFailer(failNum)
 			blockchain.hc.engine = blockchain.engine
-			failRes, err = blockchain.InsertHeaderChain(headers, 1)
+			failRes, err = blockchain.InsertHeaderChain(headers)
 		}
 		// Check that the returned error indicates the failure
 		if failRes != failAt {
@@ -785,7 +785,7 @@ func TestFastVsFullChains(t *testing.T) {
 	for i, block := range blocks {
 		headers[i] = block.Header()
 	}
-	if n, err := fast.InsertHeaderChain(headers, 1); err != nil {
+	if n, err := fast.InsertHeaderChain(headers); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
 	}
 	if n, err := fast.InsertReceiptChain(blocks, receipts, 0); err != nil {
@@ -800,7 +800,7 @@ func TestFastVsFullChains(t *testing.T) {
 	ancient, _ := NewBlockChain(ancientDb, nil, gspec, nil, ethash.NewFaker(), vm.Config{}, nil, nil)
 	defer ancient.Stop()
 
-	if n, err := ancient.InsertHeaderChain(headers, 1); err != nil {
+	if n, err := ancient.InsertHeaderChain(headers); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
 	}
 	if n, err := ancient.InsertReceiptChain(blocks, receipts, uint64(len(blocks)/2)); err != nil {
@@ -931,7 +931,7 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 	for i, block := range blocks {
 		headers[i] = block.Header()
 	}
-	if n, err := fast.InsertHeaderChain(headers, 1); err != nil {
+	if n, err := fast.InsertHeaderChain(headers); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
 	}
 	if n, err := fast.InsertReceiptChain(blocks, receipts, 0); err != nil {
@@ -947,7 +947,7 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 	ancient, _ := NewBlockChain(ancientDb, nil, gspec, nil, ethash.NewFaker(), vm.Config{}, nil, nil)
 	defer ancient.Stop()
 
-	if n, err := ancient.InsertHeaderChain(headers, 1); err != nil {
+	if n, err := ancient.InsertHeaderChain(headers); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
 	}
 	if n, err := ancient.InsertReceiptChain(blocks, receipts, uint64(3*len(blocks)/4)); err != nil {
@@ -964,7 +964,7 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 	lightDb := makeDb()
 	defer lightDb.Close()
 	light, _ := NewBlockChain(lightDb, nil, gspec, nil, ethash.NewFaker(), vm.Config{}, nil, nil)
-	if n, err := light.InsertHeaderChain(headers, 1); err != nil {
+	if n, err := light.InsertHeaderChain(headers); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
 	}
 	defer light.Stop()
@@ -1781,7 +1781,7 @@ func TestBlockchainRecovery(t *testing.T) {
 	for i, block := range blocks {
 		headers[i] = block.Header()
 	}
-	if n, err := ancient.InsertHeaderChain(headers, 1); err != nil {
+	if n, err := ancient.InsertHeaderChain(headers); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
 	}
 	if n, err := ancient.InsertReceiptChain(blocks, receipts, uint64(3*len(blocks)/4)); err != nil {
@@ -1850,7 +1850,7 @@ func TestInsertReceiptChainRollback(t *testing.T) {
 	for i, block := range canonblocks {
 		canonHeaders[i] = block.Header()
 	}
-	if _, err = ancientChain.InsertHeaderChain(canonHeaders, 1); err != nil {
+	if _, err = ancientChain.InsertHeaderChain(canonHeaders); err != nil {
 		t.Fatal("can't import canon headers:", err)
 	}
 
@@ -2128,7 +2128,7 @@ func testInsertKnownChainData(t *testing.T, typ string) {
 			for _, block := range blocks {
 				headers = append(headers, block.Header())
 			}
-			_, err := chain.InsertHeaderChain(headers, 1)
+			_, err := chain.InsertHeaderChain(headers)
 			return err
 		}
 		asserter = func(t *testing.T, block *types.Block) {
@@ -2142,7 +2142,7 @@ func testInsertKnownChainData(t *testing.T, typ string) {
 			for _, block := range blocks {
 				headers = append(headers, block.Header())
 			}
-			_, err := chain.InsertHeaderChain(headers, 1)
+			_, err := chain.InsertHeaderChain(headers)
 			if err != nil {
 				return err
 			}
@@ -2299,7 +2299,7 @@ func testInsertKnownChainDataWithMerging(t *testing.T, typ string, mergeHeight i
 			for _, block := range blocks {
 				headers = append(headers, block.Header())
 			}
-			i, err := chain.InsertHeaderChain(headers, 1)
+			i, err := chain.InsertHeaderChain(headers)
 			if err != nil {
 				return fmt.Errorf("index %d, number %d: %w", i, headers[i].Number, err)
 			}
@@ -2316,7 +2316,7 @@ func testInsertKnownChainDataWithMerging(t *testing.T, typ string, mergeHeight i
 			for _, block := range blocks {
 				headers = append(headers, block.Header())
 			}
-			i, err := chain.InsertHeaderChain(headers, 1)
+			i, err := chain.InsertHeaderChain(headers)
 			if err != nil {
 				return fmt.Errorf("index %d: %w", i, err)
 			}
@@ -2492,7 +2492,7 @@ func TestReorgToShorterRemovesCanonMappingHeaderChain(t *testing.T) {
 	for i, block := range canonblocks {
 		canonHeaders[i] = block.Header()
 	}
-	if n, err := chain.InsertHeaderChain(canonHeaders, 0); err != nil {
+	if n, err := chain.InsertHeaderChain(canonHeaders); err != nil {
 		t.Fatalf("header %d: failed to insert into chain: %v", n, err)
 	}
 	canonNum := chain.CurrentHeader().Number.Uint64()
@@ -2501,7 +2501,7 @@ func TestReorgToShorterRemovesCanonMappingHeaderChain(t *testing.T) {
 	for i, block := range sideblocks {
 		sideHeaders[i] = block.Header()
 	}
-	if n, err := chain.InsertHeaderChain(sideHeaders, 0); err != nil {
+	if n, err := chain.InsertHeaderChain(sideHeaders); err != nil {
 		t.Fatalf("header %d: failed to insert into chain: %v", n, err)
 	}
 	head := chain.CurrentHeader()
@@ -2692,7 +2692,7 @@ func TestSkipStaleTxIndicesInSnapSync(t *testing.T) {
 	for i, block := range blocks {
 		headers[i] = block.Header()
 	}
-	if n, err := chain.InsertHeaderChain(headers, 0); err != nil {
+	if n, err := chain.InsertHeaderChain(headers); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
 	}
 	// The indices before ancient-N(32) should be ignored. After that all blocks should be indexed.

core/genesis.go

@@ -379,11 +379,9 @@ func SetupGenesisBlockWithOverride(db ethdb.Database, triedb *trie.Database, gen
 	return newcfg, stored, nil
 }
 
-// LoadCliqueConfig loads the stored clique config if the chain config
-// is already present in database, otherwise, return the config in the
-// provided genesis specification. Note the returned clique config can
-// be nil if we are not in the clique network.
-func LoadCliqueConfig(db ethdb.Database, genesis *Genesis) (*params.CliqueConfig, error) {
+// LoadChainConfig loads the stored chain config if it is already present in
+// database, otherwise, return the config in the provided genesis specification.
+func LoadChainConfig(db ethdb.Database, genesis *Genesis) (*params.ChainConfig, error) {
 	// Load the stored chain config from the database. It can be nil
 	// in case the database is empty. Notably, we only care about the
 	// chain config corresponds to the canonical chain.
@@ -391,10 +389,10 @@ func LoadCliqueConfig(db ethdb.Database, genesis *Genesis) (*params.CliqueConfig
 	if stored != (common.Hash{}) {
 		storedcfg := rawdb.ReadChainConfig(db, stored)
 		if storedcfg != nil {
-			return storedcfg.Clique, nil
+			return storedcfg, nil
 		}
 	}
-	// Load the clique config from the provided genesis specification.
+	// Load the config from the provided genesis specification
 	if genesis != nil {
 		// Reject invalid genesis spec without valid chain config
 		if genesis.Config == nil {
@@ -407,12 +405,11 @@ func LoadCliqueConfig(db ethdb.Database, genesis *Genesis) (*params.CliqueConfig
 		if stored != (common.Hash{}) && genesis.ToBlock().Hash() != stored {
 			return nil, &GenesisMismatchError{stored, genesis.ToBlock().Hash()}
 		}
-		return genesis.Config.Clique, nil
+		return genesis.Config, nil
 	}
 	// There is no stored chain config and no new config provided,
-	// In this case the default chain config(mainnet) will be used,
-	// namely ethash is the specified consensus engine, return nil.
-	return nil, nil
+	// In this case the default chain config(mainnet) will be used
+	return params.MainnetChainConfig, nil
 }
 
 func (g *Genesis) configOrDefault(ghash common.Hash) *params.ChainConfig {

core/headerchain.go

@@ -300,7 +300,7 @@ func (hc *HeaderChain) writeHeadersAndSetHead(headers []*types.Header, forker *F
 	return result, nil
 }
 
-func (hc *HeaderChain) ValidateHeaderChain(chain []*types.Header, checkFreq int) (int, error) {
+func (hc *HeaderChain) ValidateHeaderChain(chain []*types.Header) (int, error) {
 	// Do a sanity check that the provided chain is actually ordered and linked
 	for i := 1; i < len(chain); i++ {
 		if chain[i].Number.Uint64() != chain[i-1].Number.Uint64()+1 {
@@ -322,23 +322,8 @@ func (hc *HeaderChain) ValidateHeaderChain(chain []*types.Header, checkFreq int)
 			return i, ErrBannedHash
 		}
 	}
-
-	// Generate the list of seal verification requests, and start the parallel verifier
-	seals := make([]bool, len(chain))
-	if checkFreq != 0 {
-		// In case of checkFreq == 0 all seals are left false.
-		for i := 0; i <= len(seals)/checkFreq; i++ {
-			index := i*checkFreq + hc.rand.Intn(checkFreq)
-			if index >= len(seals) {
-				index = len(seals) - 1
-			}
-			seals[index] = true
-		}
-		// Last should always be verified to avoid junk.
-		seals[len(seals)-1] = true
-	}
-
-	abort, results := hc.engine.VerifyHeaders(hc, chain, seals)
+	// Start the parallel verifier
+	abort, results := hc.engine.VerifyHeaders(hc, chain)
 	defer close(abort)
 
 	// Iterate over the headers and ensure they all check out