Re: [Caml-list] Ocaml on an embedded arm system (no linux)

[Gerd Stolpmann <info@gerd-stolpmann.de>]

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Am Freitag, den 20.09.2013, 09:13 -0500 schrieb Dwight Schauer:

> The ARM processors I'm looking to target are:
> STM32F407ZGT6 ARM Cortex-M4, 1MB Flash, 196KB RAM (Has floating point)
> STM32F103RB ARM Cortex-M3, 128 KB Flash, 20K RAM (No floating point)

I hope this isn't a typo. 196 KB RAM is way too low to even run a hello
world program. The predecessor of ocaml, caml-light, needed 640K at
minimum for running it on DOS, and that was 16 bit code. Ocaml is a lot
larger, and generates less dense 32 bit code.

For a very small app on bare metal, I think you need at least 4-8 MB of
memory. For making you happy, calculate 64 MB. I cannot say much about
the split flash mem vs. RAM - but you should take into account that the
representation of values isn't optimized for compactness, and you also
need extra RAM to give the garbage collector room.

Maybe it is possible to lower the memory requirements by modifying the
ocaml runtime (e.g. make the bytecode more compact at the cost of extra
decoding steps, remove unneeded parts like the compactor, ...), but I
doubt you'll be able to hit the mentioned limits.

Gerd


> 
> 
> On both I'd like to be able to run bytecode both out of Flash and RAM.
> (Primarily flash, but RAM for debugging).
> 
> 
> Speed is on overly important as long as I can control when the garbage
> collection is run (could be done in C in the multitasker?).
> 
> 
> 
> Dwight
> 
> 

-- 
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Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
Creator of GODI and camlcity.org.
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
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