diff --git a/xcache.ini b/xcache.ini
index e8a3d63..606251d 100644
--- a/xcache.ini
+++ b/xcache.ini
@@ -37,6 +37,7 @@ xcache.readonly_protection = Off
 ; for win32, xcache.mmap_path=anonymous map name, not file path
 ; uncomment and change to "/tmp/xcache" for readonly protection
 ; 2 group of php won't share the same /tmp/xcache
+; for other OS, it's a file NOT directory
 xcache.mmap_path =    "/dev/zero"