+ -- Eitherness reflects the difficulty of dealing with
+ -- MachAddr here, mostly due to the excessive
+ -- (and unnecessary) restrictions imposed by the designers
+ -- of the new Foreign library. In particular it is quite
+ -- impossible to convert an Addr to any other integral type,
+ -- and it appears impossible to get hold of the bits of an
+ -- addr, even though we need to to assemble BCOs.
+