RIOT can support larger processors with more RAM. I recently ported RIOT
to a Zynq FPGA containing ARM Cortex A9 with 512MB RAM. It is unlikely
that this would ever be used as a IoT device due to the cost and power
consumption however it is a fantastic development/prototyping platform.
https://github.com/RIOT-OS/RIOT/pull/3491
Simon
On 12/08/15 03:38, Zac Harvey wrote:
Thanks Marc, I appreciate the candid input. I have a few final (I
promise) followups here that are more for my edification/learning than
anything else.
You say that RIOT is meant for *small* systems, and I think I'm
beginning to understand what that means. But regardless of what RIOT
is *typically* used for, are there any inherent limitations in RIOT
that would prevent me from deploying/flashing it to a sophisticated
MCU that *could* run Java? In other words, say I have an MCU that has
a crazy amount of ROM/RAM on it that has the stats to handle a full
bore JVM app...does RIOT itself have any limitation/constraints that
would prevent me from choosing it (nevermind *why* I would choose it
in the first place!)?
Also, I get that MCU ROM is the memory where the executable is flashed
to. And I understand that because of this, in order for a non-running
executable to fit on an MCU, it must have a file size that is
smaller than the amount of ROM (obviously). But I'm still not
understanding why the RAM (that is, the memory allocated to the
running executable) can't be scalable by somehow attaching additional
storage (flash/whatever) to the MCU. In other words, if the sam3x8e
has 512KB ROM and only 96KB RAM, if my entire JVM executable (which
includes *everything*) is somehow magically less than 512KB, it will
fit on the MCU. So why can't I then get around the 96KB RAM
limitation by (somehow) integrating that onboard 96KB RAM with, say,
an 8GB solid state drive, or something thereabouts. I just feel like
there *must* be a way to scale the RAM and perhaps even the ROM. Ideas?
Thanks again, if I can get answers to these I should be all set!
Best,
Zac
On 8/11/15 5:19 PM, Marc Sissom wrote:
Hi Zac,
Have you looked at the sam3x8e datasheet? Right on the front page it
says it has 512KB of flash (AKA ROM or nonvolatile program and data
storage). The chip has 96KB of RAM. Looking into task manager on
Windows 7 I see a javaw.exe that is occupying 133MB of RAM and my JRE
takes up 153MB of disk. Admittedly this is not a perfect comparison,
but surely these numbers mean something to you.
RIOT is meant for *small* systems. Not SMALL or S M A L L but small
systems. Some of these systems are so small that they can't do Hello
World because the printf code takes up too much space.
Thoughts? Criticisms? Hate mail?
In other words, you're nuts!
;-)
Given that, here's a true Java bytecode chip that I worked with a few
years back:
http://www.ajile.com/index.php?option=com_contentview=articleid=2Itemid=6
Here's an FPGA core:
http://www.jopdesign.com/
And an ARM product:
https://en.wikipedia.org/wiki/Jazelle
In other words, you are not the first to think of this, and in some
cases it's not a bad idea. On the other hand, I think you can safely
forget Akka on RIOT.
You also mentioned Python; have a look here:
http://micropython.org/
Enjoy!
Marc Sissom
Krypton Solutions
-Original Message-
From: devel [mailto:devel-boun...@riot-os.org] On Behalf Of Zac Harvey
Sent: Tuesday, August 11, 2015 3:23 PM
To: RIOT OS kernel developers
Subject: Re: [riot-devel] HotSpot JVM on RIOT-OS?
Thanks Kaspar and Joakim,
I'm not trying to be difficult here (I promise!) I'm just trying to
see the forest through the trees.
When you say that The OpenJDK would probably require many megabytes
of both ROM and RAM, this means it will not run on the sam3x8e...,
why? Is it because it would require many megabytes, or because it
requires ROM, which I'm guessing isn't supported by RIOT-OS?
And yes, I will definitely dive into Darjeeling/LLVM, but am trying
to see if I can't brute force an easier solution first. :-)
Thanks again!
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