Hello demo program

Makefile

@@ -120,6 +120,7 @@ mkfs/mkfs: mkfs/mkfs.c $K/fs.h $K/param.h
 UPROGS=\
 	$U/_cat\
 	$U/_echo\
+	$U/_hello\
 	$U/_forktest\
 	$U/_grep\
 	$U/_init\
@@ -136,6 +137,7 @@ UPROGS=\
 	$U/_zombie\
 	$U/_clear\
 	$U/_halt\
+	$U/_reset\
 
 fs.img: mkfs/mkfs README.md $(UPROGS)
 	mkfs/mkfs fs.img README.md $(UPROGS)

kernel/syscall.c

@@ -103,6 +103,7 @@ extern u64 sys_mkdir(void);
 extern u64 sys_close(void);
 extern u64 sys_trace(void);
 extern u64 sys_halt(void);
+extern u64 sys_reset(void);
 
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
@@ -112,7 +113,7 @@ 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_halt] = sys_halt,
+  [SYS_close] = sys_close, [SYS_trace] = sys_trace,   [SYS_halt] = sys_halt,     [SYS_reset] = sys_reset,
 };
 
 void

kernel/syscall.h

@@ -24,3 +24,4 @@
 #define SYS_close  21
 #define SYS_trace  22
 #define SYS_halt   23
+#define SYS_reset  24

kernel/sysproc.c

@@ -101,5 +101,14 @@ void
 sys_halt(void)
 {
   (*(volatile u32 *)QEMU_POWER) = 0x5555;
-  panic("sys_poweroff");
+  panic("sys_halt");
+}
+
+void
+sys_reset(void)
+{
+  // TODO: Revisit and review
+  // asm volatile("j _entry");
+  (*(volatile u32 *)QEMU_POWER) = 0x3333;
+  panic("sys_reset");
 }

user/hello.c

@@ -0,0 +1,13 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+
+int
+main(int argc, char *argv[])
+{
+  char hello[] = "Hello XV6!\n";
+
+  write(1, hello, sizeof(hello));
+
+  exit(0);
+}

user/reset.c

@@ -0,0 +1,10 @@
+#include "user.h"
+
+/** Reset the machine */
+int
+main(int argc, char *argv[])
+{
+  printf("System resetting...\n");
+  reset();
+  return 0;
+}

user/user.h

@@ -80,6 +80,9 @@ int trace(int);
 /** halt */
 void halt(void);
 
+/** halt */
+void reset(void);
+
 /**
  * Library functions (ulib.c)
  */

user/usertests.c

@@ -239,7 +239,7 @@ copyinstr3(char *s)
 // See if the kernel refuses to read/write user memory that the
 // application doesn't have anymore, because it returned it.
 void
-rwsbrk()
+rwsbrk(char *unused)
 {
   int fd, n;
 

user/usys.py

@@ -40,6 +40,7 @@ syscalls = [
     "uptime",
     "trace",
     "halt",
+    "reset",
 ]
 
 assembly = "\n\n".join(map(genstub, syscalls))