--- xen-4.5.1/xen/arch/x86/Rules.mk.orig 2015-05-18 18:20:57.000000000 +0100
+++ xen-4.5.1/xen/arch/x86/Rules.mk 2015-05-30 21:24:31.886886843 +0100
@@ -48,3 +48,4 @@
ifneq ($(call cc-option,$(CC),-fvisibility=hidden,n),n)
CFLAGS += -DGCC_HAS_VISIBILITY_ATTRIBUTE
endif
+CFLAGS += -fno-caller-saves