锯齿螈完成

This reverts commit 40906323d2.

ch3-coop/os/Makefile

@@ -4,7 +4,7 @@ MODE := release
 KERNEL_ELF := target/$(TARGET)/$(MODE)/os
 KERNEL_BIN := $(KERNEL_ELF).bin
 SYMBOL_MAP := target/system.map
-QEMU_CMD_PATH := ../../tools/qemu-system-riscv64
+QEMU_CMD_PATH := /Users/zhangxinyu/Downloads/qemu-7.0.0/build/qemu-system-riscv64
 QEMU_PID = $(shell ps aux | grep "[q]emu-system' | awk '{print $$2}")
 OBJDUMP := rust-objdump --arch-name=riscv64
 OBJCOPY := rust-objcopy --binary-architecture=riscv64

ch3-coop/user/src/syscall.rs

@@ -29,7 +29,7 @@ pub fn sys_exit(exit_code: i32) -> isize {
     syscall(SYSCALL_EXIT, [exit_code as usize, 0, 0])
 }
 
-pub fn sys_yield() {
-    syscall(SYSCALL_YIELD, [0, 0, 0]);
-}
+// pub fn sys_yield() {
+//     syscall(SYSCALL_YIELD, [0, 0, 0]);
+// }