rCore-Tutorial-Guide-2025S/chapter1/3mini-rt-usrland

[utterances-bot]

构建用户态执行环境 - rCore-Tutorial-Guide-2025S 文档

https://learningos.cn/rCore-Tutorial-Guide-2025S/chapter1/3mini-rt-usrland.html

[SilentThink]

use core::fmt::{Write};
use core::fmt;
需要在main.rs中导入才能编译运行

[miaooo0000OOOO]

如果编译出现以下报错：

error[E0624]: method `as_statically_known_str` is private

在文件中添加

#![feature(fmt_internals)]

[chenjiuhai]

#![no_std]
#![no_main]

use core::fmt::{self, Write};

mod lang_items;

const SYSCALL_WRITE: usize = 64;
const SYSCALL_EXIT: usize = 93;

fn syscall(id: usize, args: [usize; 3]) -> isize {
let mut ret;
unsafe {
core::arch::asm!(
"ecall",
inlateout("x10") args[0] => ret,
in("x11") args[1],
in("x12") args[2],
in("x17") id,
);
}
ret
}

pub fn sys_write(fd: usize, buffer: &[u8]) -> isize {
syscall(SYSCALL_WRITE, [fd, buffer.as_ptr() as usize, buffer.len()])
}

pub fn sys_exit(xstate: i32) -> isize {
syscall(SYSCALL_EXIT, [xstate as usize, 0, 0])
}

struct Stdout;

impl Write for Stdout {
fn write_str(&mut self, s: &str) -> fmt::Result {
sys_write(1, s.as_bytes());
Ok(())
}
}

pub fn print(args: fmt::Arguments) {
Stdout.write_fmt(args).unwrap();
}

#[macro_export]
macro_rules! print {
($fmt: literal $(, $($arg: tt)+)?) => {
$crate::console::print(format_args!($fmt $(, $($arg)+)?));
};
}

#[macro_export]
macro_rules! println {
($fmt: literal $(, $($arg: tt)+)?) => {
print(format_args!(concat!($fmt, "\n") $(, $($arg)+)?));
};
}

#[no_mangle]
extern "C" fn _start() {
println!("Hello world!");
sys_exit(9);
}

[blacksheepaul]

如果cargo build出现 "error: unsafe attribute used without unsafe"

需要将#[no_mangle]改成#[unsafe(no_mangle)]

有条件的话使用和教材一致的Rust版本(nightly-2024-05-02)，避免因环境差异导致的各种问题分心