cmd/geth: corrently init gas price for CLI CPU mining

cmd/geth/main.go

@@ -252,10 +252,12 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 	}()
 	// Start auxiliary services if enabled
 	if ctx.GlobalBool(utils.MiningEnabledFlag.Name) {
+		// Mining only makes sense if a full Ethereum node is running
 		var ethereum *eth.Ethereum
 		if err := stack.Service(&ethereum); err != nil {
 			utils.Fatalf("ethereum service not running: %v", err)
 		}
+		// Use a reduced number of threads if requested
 		if threads := ctx.GlobalInt(utils.MinerThreadsFlag.Name); threads > 0 {
 			type threaded interface {
 				SetThreads(threads int)
@@ -264,6 +266,8 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 				th.SetThreads(threads)
 			}
 		}
+		// Set the gas price to the limits from the CLI and start mining
+		ethereum.TxPool().SetGasPrice(utils.GlobalBig(ctx, utils.GasPriceFlag.Name))
 		if err := ethereum.StartMining(true); err != nil {
 			utils.Fatalf("Failed to start mining: %v", err)
 		}