主文件中如果 mod port; 放在 main 函数后面则可以正常进入 文本模式，如果放在 main 函数前则无法进入文本模式 主文件

#![no_std]
#![feature(custom_attribute,asm)]
#![allow(improper_ctypes)]
//mod color;
mod kernel;

use kernel::Color;
use kernel::Size;
use kernel::Console;
use port::UnsafePort;


#[no_mangle]
pub unsafe fn main() {
    let mut console = Console::new(Size::new(80, 25), Color::Black, Color::White);
    console.println("Hello world!");
    loop {
        let a = UnsafePort::new(0x60).read();
        console.put_char(Color::Black, Color::White, a);
    }
}
mod port;

引入的文件

#![allow(dead_code)]
use kernel::unsafe_func::inb;
use kernel::unsafe_func::outb;
use kernel::unsafe_func::inw;
use kernel::unsafe_func::outw;
use kernel::unsafe_func::inl;
use kernel::unsafe_func::outl;
use core::marker::PhantomData;

pub trait InOut {
    unsafe fn port_in(port: u32) -> Self;
    unsafe fn port_out(port: u32, value: Self);
}

impl InOut for u8 {
    unsafe fn port_in(port: u32) -> u8 { inb(port) }
    unsafe fn port_out(port: u32, value: u8) { outb(value, port); }
}

impl InOut for u16 {
    unsafe fn port_in(port: u32) -> u16 { inw(port) }
    unsafe fn port_out(port: u32, value: u16) { outw(value, port); }
}

impl InOut for u32 {
    unsafe fn port_in(port: u32) -> u32 { inl(port) }
    unsafe fn port_out(port: u32, value: u32) { outl(value, port); }
}

pub struct UnsafePort<T: InOut> {
    port: u32,
    phantom: PhantomData<T>,
}

impl<T: InOut> UnsafePort<T> {
    pub unsafe fn new(port: u32) -> UnsafePort<T> {
        UnsafePort { port: port, phantom: PhantomData }
    }

    pub unsafe fn read(&mut self) -> T {
        T::port_in(self.port)
    }

    pub unsafe fn write(&mut self, value: T) {
        T::port_out(self.port, value);
    }
}