Index: kernel/arch/amd64/include/atomic.h
===================================================================
--- kernel/arch/amd64/include/atomic.h	(revision 228666c006a3414de772f08f77335c546dd21aab)
+++ kernel/arch/amd64/include/atomic.h	(revision ba371e15eb85077a9be68f740a43f1ad373096de)
@@ -101,10 +101,9 @@
 static inline atomic_count_t test_and_set(atomic_t *val)
 {
-	atomic_count_t v;
+	atomic_count_t v = 1;
 	
 	asm volatile (
-		"movq $1, %[v]\n"
 		"xchgq %[v], %[count]\n"
-		: [v] "=r" (v),
+		: [v] "+r" (v),
 		  [count] "+m" (val->count)
 	);