Defer kernel panic when Kmain returns

src/gopheros/kernel/kmain/kmain.go

@@ -39,10 +39,13 @@ func Kmain(multibootInfoPtr, kernelStart, kernelEnd, kernelPageOffset uintptr) {
 		panic(err)
 	}
 
-	// Detect and initialize hardware
-	hal.DetectHardware()
-
+	// After goruntime.Init returns we can safely use defer
+	defer func() {
 		// Use kfmt.Panic instead of panic to prevent the compiler from
 		// treating kernel.Panic as dead-code and eliminating it.
 		kfmt.Panic(errKmainReturned)
+	}()
+
+	// Detect and initialize hardware
+	hal.DetectHardware()
 }