added shutdown

common.h

@@ -25,6 +25,7 @@ typedef uint32_t vaddr_t;
 #define SYS_EXIT    3
 #define SYS_READFILE  4
 #define SYS_WRITEFILE 5
+#define SYS_SHUTDOWN 6
 
 void *memset(void *buf, char c, size_t n);
 void *memcpy(void *dst, const void *src, size_t n);

kernel.c

@@ -268,6 +268,10 @@ long getchar(void) {
     return ret.error;
 }
 
+void shutdown(void) {
+    sbi_call(0, 0, 0, 0, 0, 0, 0, 8 /* Shutdown */);
+}
+
 __attribute__((naked))
 __attribute__((aligned(4)))
 void kernel_entry(void) {
@@ -528,6 +532,10 @@ void handle_syscall(struct trap_frame *f) {
             f->a0 = len;
             break;
         }
+        case SYS_SHUTDOWN:
+            printf("shuting down\n");
+            shutdown();
+            break;
         default:
             PANIC("unexpected syscall a3=%x\n", f->a3);
     }

shell.c

@@ -32,6 +32,8 @@ void main(void) {
         }
         else if (strcmp(cmdline, "writefile") == 0)
             writefile("hello.txt", "Hello from shell!\n", 19);
+        else if (strcmp(cmdline, "shutdown") == 0)
+            shutdown();
         else
             printf("unknown command: %s\n", cmdline);
     }

user.c

@@ -32,6 +32,10 @@ int writefile(const char *filename, const char *buf, int len) {
     return syscall(SYS_WRITEFILE, (int) filename, (int) buf, len);
 }
 
+int shutdown(void) {
+    return syscall(SYS_SHUTDOWN, 0, 0, 0);
+}
+
 __attribute__((noreturn)) void exit(void) {
     syscall(SYS_EXIT, 0, 0, 0);
     for (;;);

user.h

@@ -11,4 +11,5 @@ void putchar(char ch);
 int getchar(void);
 int readfile(const char *filename, char *buf, int len);
 int writefile(const char *filename, const char *buf, int len);
+int shutdown(void);
 __attribute__((noreturn)) void exit(void);