Re: [Caml-list] OCaml embedded

[Francois Berenger <francois.berenger@inria.fr>]

On 06/26/2015 05:04 AM, Berke Durak wrote:
> On Tue, Jun 23, 2015 at 6:32 AM, Markus Weißmann
> <markus.weissmann@in.tum.de> wrote:
>>
>> I can offer experience in the following cases:
>> 1) If your system is powerful enough (e.g. rasperry pi), you can just install the ocaml toolchain on your system and develop there on your target system.
>
> Seconded.  We did almost that for one of our projects and it works
> pretty well.  The difference is that we didn't use QEmu, but two of
> our custom Q7 board (based on a Zynq ARM Cortex A9 with 512 MB RAM,
> see http://xiphos.com/products/q7-processor/ ).
>
> We use Yocto to generate two versions of a Linux system: the target
> system, and a much larger version that contains developer tools (C
> compiler, m4, etc.)  The development system runs from microSD cards,
> and takes the better part of a gigabyte, while the target system has
> to run from < 64 megs of flash.  The required run-time dependencies of
> the target system have to be manually configured in the Yocto recipes.
>
> We then manually install opam on the developer board, and use it to
> compile our OCaml code. The generated native ARM executables are then
> packaged into .ipks and transferred to the target Q7 board (connected
> to actual hardware:
> http://www.ghgsat.com/wp-content/uploads/2015/03/Payload-Selfie.jpg )
> The packaging is done using a simple shell script that invokes ar and
> tar.
>
> We did try using QEmu but it's significantly slower, however it may
> come into play as automating the build process (using a virtual
> machine or dedicated hardware) is on our to do list, and build time
> isn't as important when it's a nightly automated build.
>
> Initially we looked into using a cross-compiler but we decided that
> being able to use Opam largely outweighs any possible benefit we could
> get from cross-compiling.

If the feature request for opam called opam-mkbundle

cf. https://github.com/ocaml/opam/issues/929

is implemented some day, this would allow people to
ship ocaml software as source code without requiring
end users to install opam.

>  And cross-compiling is often a source of
> headaches, even when compiling plain old C.  We would have to write a
> lot of Yocto recipes to get it running.  Note that Yocto is written in
> a progarmming language called Python and requires recipes to be
> expressed mostly the same language.
>
> To conclude, as powerful ARM systems are very cheap and plentiful
> these days, and since the convenience of Opam is immense, I'm not sure
> there is much incentive in using a cross-compiler.  BTW, is there a
> maintained ARM cross-compiler?
>

-- 
Regards,
Francois.
"When in doubt, use more types"