Re: [Caml-list] 64-bit OCaml?

[Sven Luther <sven.luther@wanadoo.fr>]

On Fri, Nov 05, 2004 at 09:02:11PM -0700, David McClain wrote:
> Hi,
> 
> I just obtained a new iMac G5 here. My cursory understanding is that this is
> a 64 bit core processor. However, when I attempted to run config for
> rebuilding the OCaml system, it reports a 32 bit system. What can or must I
> do to coax OCaml to become a 64 bit system for this processor?

This one i can reply, well, sort off.

The G5, which is really the ppc970 cpu from ibm, is a derivative of the power3
and power4 ibm processors. As thus, it can run both 32bit and 64bit code.

The you need to know what operating system you are running on it, but you
probably run mac os x, but in the linux case, you can have both a 32bit kernel
or a 64bit kernel. Of the linux distributions out there, not all support a
64bit kernel. on top of a 32bit kernel, you can run a 32bit userland only,
while on a 64bit kernel, you can run a 32bit or a true 64bit userland.

So, to take advantage of the 64bitness of the ppc970, you need a 64bit kernel,
and either a pure 64bit userland, or a dual userland, that is one which is
able to run both 32bit and 64bit code, but which is mostly 32bit usually.

Now, and here i believe it applies also to the mac os x case, in all case that
support 64bit userland, the actual programs, and among them ocaml, need to :

  1) detect that they are on a 64bit capable system.

  2) take advantage of the 64bitness of the system.

In the ocaml case, 1) should be rather easy, an adaptation of the configure
scripts probably only, as ocaml already supports 64bit. 2) is needs more work
though, and i don't believe there is already ppc 64bit support.

Friendly,

Sven LUther