ocaml cross-compilation and bootable image

ocaml cross-compilation and bootable image

[Dave Mason]

I'm running ocamlopt on an Alpha (Linux) but need to generate i386
binary executables.

Has anyone done this?  Any hints on how to do it?

(I'm going to be creating a bootable kernel image as part of the FunOS
project - see http://sarg.ryerson.ca/FunOS/ if interested.  Yes,
obviously I could build natively on an i386 box, but we'll initially
be using the bochs emulator, and the Alpha is a lot faster.)

Thanks	../Dave

Re: ocaml cross-compilation and bootable image

[Xavier Leroy]

> I'm running ocamlopt on an Alpha (Linux) but need to generate i386
> binary executables.
> Has anyone done this?  Any hints on how to do it?

I never tried to set up a full cross-compiler, but it should not be
hard.  You need to run the configure script, then edit the generated
file config/Makefile and change the following variables:

ARCH=<your target architecture, e.g. i386>
MODEL=default
SYSTEM=<your target OS (for choosing calling conventions, etc), e.g. linux_elf>
NATIVECC=<your cross C compiler, e.g. myarch-gcc>
NATIVECCCOMPOPTS=<whatever options you need at compile-time>
NATIVECCLINKOPTS=<whatever options you need at link-time>
ASPP=<your cross assembler with preprocessing, e.g. myarch-gcc>
ASPPFLAGS=-c -DSYS_$(SYSTEM) <extra options if needed>

Finally, the name of the assembler called to assemble the output of
ocamlopt is (unfortunately) hard-wired in asmcomp/<arch>/proc.ml,
function assemble_file, so you may need to change that file.
Or just play with $PATH until "as" refers to your cross-assembler.

There's also a hard-wired call to "ar" in utils/ccomp.ml that may need
to be changed.

Good luck,

- Xavier Leroy