diff --git a/ChangeLog b/ChangeLog
index cee27499f..92e80305b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2000-01-11  OKUJI Yoshinori  <okuji@gnu.org>
+
+	* docs/prog-ref.texi (LBA mode disk I/O): Added a footnote about
+	a buggy BIOS.
+	
 2000-01-11  OKUJI Yoshinori  <okuji@gnu.org>
 
 	* stage1/stage1.S [!NO_BUGGY_BIOS_IN_THE_WORLD]: Don't check if
diff --git a/docs/prog-ref.texi b/docs/prog-ref.texi
index f357f1a17..40c9802c1 100644
--- a/docs/prog-ref.texi
+++ b/docs/prog-ref.texi
@@ -1060,7 +1060,9 @@ otherwise 01h (the error code of @dfn{invalid function}).
 @item @code{DH} @tab Extension version.
 @end multitable
 
-The bitfields for the API subset support bitmap are:
+The bitfields for the API subset support bitmap are@footnote{It is known
+that (at least) the AMI BIOS in SuperMicro P6SBA motherboard
+(AMIBIOSC0631) does @emph{not} return the bitfields correctly.}:
 
 @multitable @columnfractions 0.15 0.85
 @item Bit(s) @tab Description