changed page allocation to happen on page fault for performance reasons

kernel/src/main.rs

@@ -28,6 +28,13 @@ extern "C" fn kmain() -> ! {
     println!("Dimensions: {}x{} (chars)", dimensions.0, dimensions.1);
 
     let mut executor = Executor::new();
+
+    let mut v = Vec::with_capacity(1000 * 1000);
+    for i in 0..1000 * 1000 {
+        v.push(i);
+    }
+    println!("v.len(): {}", v.len());
+
     executor.spawn(Task::new(shell()));
     executor.run();
 }