diff --git a/os/src/main.rs b/os/src/main.rs
index 2c02e972..fcb396cc 100644
--- a/os/src/main.rs
+++ b/os/src/main.rs
@@ -23,7 +23,7 @@ mod sbi;
 global_asm!(include_str!("entry.asm"));
 
 /// clear BSS segment
-fn clear_bss() {
+pub fn clear_bss() {
     extern "C" {
         fn sbss();
         fn ebss();