Only allow CONFIG_XEN when not CONFIG_COREBOOT.
diff --git a/src/Kconfig b/src/Kconfig
index b9875c8..bbed963 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -11,6 +11,7 @@
             Configure as a coreboot payload.
 
     config XEN
+        depends on !COREBOOT
         bool "Build for Xen HVM"
         default n
         help