>> Is there a GNU/Linux (and OCaml) mode supporting the half-way case where
>> you use the new amd64 registers but still stay with 32bit pointers?
>> That should fix the one case where the amd64 mode is slower because of the
>> extra memory use.
> I do not believe there is such a mode, no.  I'm not entirely sure how this 
> could work

Under Alpha they called it "taso".  Mostly used for compatibility with apps
that were assuming the size of ptrs is the same as the size of int: it just
made the C library use only the bottom 4GB of the address space such that
the compiler could use only 32bit to store pointer values.


        Stefan