Re: [Caml-list] OCaml embedded

[xavier deschuyteneer <xavier.deschuyteneer@gmail.com>]

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When i say embedded system, i really mean embedded system running on a
minimal Linux with low power CPU, not so much flash, same for the RAM.
It's similar to think that a raspberry pi is a IOT. It's not, it's mini
computer on ARM platform. In my case, it's really an embedded system, low
cpu, not so much ram, neither flash.

And btw i know exactly how yocto works because i build myself our OS. And
that's not exactly python, it's a mix between python and bash.
We build two different distributions: one ARM and one x86 (for emulation
purpose, valgrind, etc.). and all tools(chains) associated.
This ocaml software needs to be integrated in this workflow.

Right now, we use plain C, and yes cross compilation is a specific setup,
but it's not difficult to achieve.
The advantage right now to use cross compilation are:
We can use all the power of a real computer to build/debug/code.
I can use all the interfaces that my computer have and not my end
(embedded) system: multiple ethernet cards, bluetooth, usb, etc.
I have multiple projects to manage and all of them are not embedded related.

Thanks for your answer and the time spent for my question :-)

TL;DR: i need to cross compile ocaml code to arm because my device is not
powerful enough and that's not possible in industrial purpose to change
that.


Xavier Deschuyteneer

2015-06-26 5:04 GMT+02:00 Berke Durak <berke.durak@gmail.com>:

> 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.  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?
> --
> Berke Durak
>
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