cmd/geth, core/vm: setup vm settings and defaulted JIT disabled

cmd/geth/main.go

@@ -336,6 +336,7 @@ JavaScript API. See https://github.com/ethereum/go-ethereum/wiki/Javascipt-Conso
 	}
 	app.Before = func(ctx *cli.Context) error {
 		utils.SetupLogger(ctx)
+		utils.SetupVM(ctx)
 		if ctx.GlobalBool(utils.PProfEanbledFlag.Name) {
 			utils.StartPProf(ctx)
 		}

core/vm/settings.go

@@ -17,9 +17,9 @@
 package vm
 
 var (
-	DisableJit  bool // Disable the JIT VM
-	ForceJit    bool // Force the JIT, skip byte VM
-	MaxProgSize int  // Max cache size for JIT Programs
+	DisableJit  bool = true // Disable the JIT VM
+	ForceJit    bool        // Force the JIT, skip byte VM
+	MaxProgSize int         // Max cache size for JIT Programs
 )
 
 const defaultJitMaxCache int = 64