Index: kernel/arch/arm32/include/asm.h
===================================================================
--- kernel/arch/arm32/include/asm.h	(revision 46a808f579ed0849ebd4d4e1aee0ddf5f989f29e)
+++ kernel/arch/arm32/include/asm.h	(revision 7c13c55aa916537b7c1133cf927f2fc37d4b4d3e)
@@ -43,7 +43,15 @@
 #include <trace.h>
 
-/** No such instruction on ARM to sleep CPU. */
+/** No such instruction on ARM to sleep CPU.
+ *
+ * ARMv7 introduced wait for event and wait for interrupt.
+ */
 NO_TRACE static inline void cpu_sleep(void)
 {
+#ifdef PROCESSOR_armv7
+	asm volatile (
+		"wfe"::
+	);
+#endif
 }