From f723ee06a975d93fcfc38de23add2d8b731b15df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=94=B0=E5=87=AF=E5=A4=AB?= <tkf19@mails.tsinghua.edu.cn>
Date: Mon, 14 Mar 2022 16:37:10 +0800
Subject: [PATCH] Update docs

---
 os/src/sbi.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/os/src/sbi.rs b/os/src/sbi.rs
index 90ba2c2a..f66d9751 100644
--- a/os/src/sbi.rs
+++ b/os/src/sbi.rs
@@ -27,14 +27,17 @@ fn sbi_call(which: usize, arg0: usize, arg1: usize, arg2: usize) -> usize {
     ret
 }
 
+/// use sbi call to putchar in console (qemu uart handler)
 pub fn console_putchar(c: usize) {
     sbi_call(SBI_CONSOLE_PUTCHAR, c, 0, 0);
 }
 
+/// use sbi call to getchar from console (qemu uart handler)
 pub fn console_getchar() -> usize {
     sbi_call(SBI_CONSOLE_GETCHAR, 0, 0, 0)
 }
 
+/// use sbi call to shutdown the kernel
 pub fn shutdown() -> ! {
     sbi_call(SBI_SHUTDOWN, 0, 0, 0);
     panic!("It should shutdown!");