1 files changed, 25 insertions, 0 deletions
diff --git a/user/lib/entry.S b/user/lib/entry.S
new file mode 100644
index 0000000..87ad9c7
--- /dev/null
+++ b/user/lib/entry.S
@@ -0,0 +1,25 @@
+//
+// user-level startup routine
+//
+	.text
+	.globl _start
+	.globl	main
+	.globl	exit
+
+// entry point - this is where the kernel starts us running
+_start:
+	// we immediately call main()
+	call main
+
+	// if we come back from that, it means the user
+	// program didn't call exit(), in which case the
+	// value returned from main() is the exit status
+
+	// push that value onto the stack and call exit()
+	subl	$12, %esp
+	pushl	%eax
+	call	exit
+
+	// if we come back from that, something bad has
+	// happened, so we just lock up
+1:	jmp 1b