Halt draft

Makefile

@@ -135,6 +135,7 @@ UPROGS=\
 	$U/_wc\
 	$U/_zombie\
 	$U/_clear\
+	$U/_halt\
 
 fs.img: mkfs/mkfs README.md $(UPROGS)
 	mkfs/mkfs fs.img README.md $(UPROGS)

kernel/syscall.c

@@ -102,6 +102,7 @@ extern u64 sys_link(void);
 extern u64 sys_mkdir(void);
 extern u64 sys_close(void);
 extern u64 sys_trace(void);
+extern u64 sys_halt(void);
 
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
@@ -111,7 +112,7 @@ static u64 (*syscalls[])(void) = {
   [SYS_chdir] = sys_chdir, [SYS_dup] = sys_dup,       [SYS_getpid] = sys_getpid, [SYS_sbrk] = sys_sbrk,
   [SYS_sleep] = sys_sleep, [SYS_uptime] = sys_uptime, [SYS_open] = sys_open,     [SYS_write] = sys_write,
   [SYS_mknod] = sys_mknod, [SYS_unlink] = sys_unlink, [SYS_link] = sys_link,     [SYS_mkdir] = sys_mkdir,
-  [SYS_close] = sys_close, [SYS_trace] = sys_trace,
+  [SYS_close] = sys_close, [SYS_trace] = sys_trace,   [SYS_halt] = sys_halt,
 };
 
 void

kernel/syscall.h

@@ -23,3 +23,4 @@
 #define SYS_mkdir  20
 #define SYS_close  21
 #define SYS_trace  22
+#define SYS_halt   23

kernel/sysproc.c

@@ -96,3 +96,9 @@ sys_trace(void)
   /* TODO: Implement sys_trace */
   return 0;
 }
+
+void
+sys_halt(void)
+{
+  /* TODO: Implement sys_halt */
+}

user/halt.c

@@ -0,0 +1,9 @@
+#include "user.h"
+
+/** Stops the machine */
+int
+main(int argc, char *argv[])
+{
+  halt();
+  return 0;
+}

user/user.h

@@ -74,6 +74,9 @@ int uptime(void);
 /** trace */
 int trace(int);
 
+/** halt */
+void halt(void);
+
 /**
  * Library functions (ulib.c)
  */

user/usys.pl

@@ -14,7 +14,7 @@ sub entry {
     print " ecall\n";
     print " ret\n";
 }
-	
+
 entry("fork");
 entry("exit");
 entry("wait");
@@ -37,3 +37,4 @@ entry("sbrk");
 entry("sleep");
 entry("uptime");
 entry("trace");
+entry("halt");