diff -r fc64f85e41cc -r 33f695f7773a docs/overview.txt
--- a/docs/overview.txt	Fri Oct 31 18:31:01 2008 +0000
+++ b/docs/overview.txt	Fri Nov 07 08:09:42 2008 +0000
@@ -565,12 +565,18 @@
              The ARM architecture.
    + optional:
        selects adequate associated config options.
+       Note: 64-bit architectures *shall* select ARCH_64
        Eg.:
          config ARCH_arm
            select ARCH_SUPPORTS_BOTH_ENDIAN
            select ARCH_DEFAULT_LE
            help
              The ARM architecture.
+       Eg.:
+         config ARCH_x86_64
+            select ARCH_64
+            help
+              The x86_64 architecture.
 
  > other target-specific options, at your discretion. Note however that to
    avoid name-clashing, such options shall be prefixed with "ARCH_%arch%",