RE: [Caml-list] Native dynlink on 3.11: a request for packagers

["David Allsopp" <dra-news@metastack.com>]

On 22 November 2008 01:20 Jon Harrop wrote:
> On Friday 21 November 2008 23:45:34 Dario Teixeira wrote:
> > Hi,
> >
> > > Does ocamlfind support any of this?  Since I'm now also
> > > cross-compiling OCaml, I've certainly come to appreciate
> > > findlib more than ever.
> >
> > Indeed it does.  The current version of Ocsigen already
> > makes use of this feature.  However, because very few
> > (none, actually, other than Ocsigen's) packages currently
> > ship with cmxs files, an Ocsigen user who wants to play
> > with native code is forced to manually generate them.
> > (What impelled me to write the request was precisely
> > having just gone through the process of producing the
> > cmxs for a bunch of Ocamlnet and PXP libraries...)
> 
> This begs the question: what is the advantage of a .cmxa over a .cmxs,
> and
> what are the downsides of linking everything dynamically?

That's reducible to the standard debate of static vs dynamic linking in any language, surely? The only "impact" on performance presumably is the re-writing of the symbol tables which flexlink/dlopen does as the .cmxs file is loaded but that must be negligible. However, isn't ocamlopt able to do some cross-module optimisation (which is why .cmx files are usually shipped as well as .cmxa) - this presumably isn't possible when linking dynamically...

Short-term, native dynlink doesn't work on all platforms (AFAIK?) so .cmxa is not dead, whatever your linking preference.


David