Support for the ARM 64 bit CPU architecture (aarch64) was introduced in autoconf 2.69. ocaml appears to use an earlier version of autoconf, preventing its being built. This can be fixed in of three ways (In order of preference): 1. Work with upstream to migrate the package to autoconf 2.69. 2. Rerun autoconf or autoreconf in %prep or %build prior to running configure. 3. Apply the patch at http://ausil.fedorapeople.org/aarch64/ocaml/ocaml-aarch64.patch which updates config.guess and config.sub to recognize aarch64.
Changing autoconf version is only about 0.1% of the problem here. We will need to write an AArch64 code generator too. I have asked upstream if anyone has looked into this, and they are looking at it but prefer to wait until real hardware is available: https://sympa.inria.fr/sympa/arc/caml-list/2013-03/msg00224.html
There is now an arm64 code gen for OCaml: https://github.com/ocaml/ocaml/tree/trunk/asmcomp/arm64
Earlier this week I backported the arm64 code gen to Rawhide. This bug is fixed in ocaml-4.01.0-6.fc21. http://koji.fedoraproject.org/koji/buildinfo?buildID=487313