syscall-add-xv6.diff

diff --git a/Makefile b/Makefile
index 09d790c..906f9d3 100644
--- a/Makefile
+++ b/Makefile
@@ -181,6 +181,7 @@ UPROGS=\
 	_usertests\
 	_wc\
 	_zombie\
+	_tryhello\
 
 fs.img: mkfs README $(UPROGS)
 	./mkfs fs.img README $(UPROGS)
diff --git a/syscall.c b/syscall.c
index ee85261..1e5198e 100644
--- a/syscall.c
+++ b/syscall.c
@@ -103,6 +103,7 @@ extern int sys_unlink(void);
 extern int sys_wait(void);
 extern int sys_write(void);
 extern int sys_uptime(void);
+extern int sys_hello(void);
 
 static int (*syscalls[])(void) = {
 [SYS_fork]    sys_fork,
@@ -126,6 +127,7 @@ static int (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
+[SYS_hello]   sys_hello,
 };
 
 void
diff --git a/syscall.h b/syscall.h
index bc5f356..5f48d9b 100644
--- a/syscall.h
+++ b/syscall.h
@@ -20,3 +20,4 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+#define SYS_hello  22
diff --git a/sysfile.c b/sysfile.c
index bfe61b7..f60f0da 100644
--- a/sysfile.c
+++ b/sysfile.c
@@ -442,3 +442,9 @@ sys_pipe(void)
   fd[1] = fd1;
   return 0;
 }
+
+int sys_hello(void)
+{
+  cprintf("hello\n");
+  return 0;
+}
diff --git a/tryhello.c b/tryhello.c
new file mode 100644
index 0000000..610d700
--- /dev/null
+++ b/tryhello.c
@@ -0,0 +1,12 @@
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fs.h"
+
+
+int
+main(int argc, char *argv[])
+{
+  hello();
+  exit();
+}
diff --git a/user.h b/user.h
index 4f99c52..2f95ca5 100644
--- a/user.h
+++ b/user.h
@@ -23,6 +23,7 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
+int hello(void);
 
 // ulib.c
 int stat(const char*, struct stat*);
diff --git a/usys.S b/usys.S
index 8bfd8a1..0072273 100644
--- a/usys.S
+++ b/usys.S
@@ -29,3 +29,4 @@ SYSCALL(getpid)
 SYSCALL(sbrk)
 SYSCALL(sleep)
 SYSCALL(uptime)
+SYSCALL(hello)