将TTY与stdio进行连接,实现基本的stdio功能 (#217)

* 将stdio与tty接上

kernel/src/lib.rs

@@ -39,7 +39,6 @@ extern crate alloc;
 extern crate bitflags;
 #[macro_use]
 extern crate lazy_static;
-
 extern crate num;
 #[macro_use]
 extern crate num_derive;
@@ -99,6 +98,5 @@ pub fn panic(info: &PanicInfo) -> ! {
 pub extern "C" fn __rust_demo_func() -> i32 {
     printk_color!(GREEN, BLACK, "__rust_demo_func()\n");
 
-
     return 0;
 }