diff --git a/README b/README
index 59f4cd2..ae9e10f 100644
--- a/README
+++ b/README
@@ -3309,6 +3309,8 @@
 
     ==> U-Boot will use R8 to hold a pointer to the global data
 
+NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
+or current versions of GCC may "optimize" the code too much.
 
 Memory Management:
 ------------------