* objdump.c (main): Issue a warning message if multiple -M

switches are used.

	* doc/binutils.texi (objdump): Update documentation about -M
	option.

binutils/doc/binutils.texi

@@ -1625,7 +1625,15 @@ architectures with the @option{-i} option.
 @item -M @var{options}
 @itemx --disassembler-options=@var{options}
 Pass target specific information to the disassembler.  Only supported on
-some targets.
+some targets.  Note only a single instance of the option on the
+command line is supported.  If the option occurs more than once, the
+earlier versions will be ignored.  If it is necessary to specify more
+than one disassembler option then they should be placed together into
+a space separated list.  ie:
+
+@smallexample
+  -M"first-disassembler-option second-disassembler-option"
+@end smallexample
 
 If the target is an ARM architecture then this switch can be used to
 select which register name set is used during disassembler.  Specifying