Re: AMP on an SMP system

[Michael Schnell <mschnell@lumino.de>]

On 08/05/2013 10:17 AM, Robert Schwebel wrote:
> On Mon, Aug 05, 2013 at 09:25:18AM +0200, Michael Schnell wrote:
>>> You can't. And you can't, even if you try to run bare-metal software
>>> on a dedicated core. I can't imagine how for example the cache
>>> influences between the cores could be determined.
>> This would render all efforts for hard realtime embedded Linux
>> applications useless. You always need to calculate the max latency.
> You can't calculate the max latency with today's complex processor
> hardware any more. It's all a matter of system failure probabilities.
So don't use them for realtime embedded applications ?

There are companies such as SysGo that seem to claim this possibility 
with their PikeOS (see 
http://www.sysgo.com/products/pikeos-rtos-and-virtualization-concept/rtos-technology/ 
). AFAIK, they don't even are able to use dedicated cores (yet). Of 
course they don't support "virtual peripheral" technology here, but 
strict determinism is a strung requirement with the critical "security" 
applications they have in mind.


> Nevertheless, there always have been settings where you could get rid 
> of all realtime complexity by spending a 1-Euro microcontroller to the 
> BOM. 

For "virtual peripherals" applications you will need either a fast CPU 
or an FPGA.

> AM335x has PRU subprocessors (not ARM architecture).
The 4788 page "AM335x Applications Processor Technical Reference Manual" 
(SPRUH73 – October 2011) on page 226 depicts the "ARM Cortex M3 Memory 
Map".

> What kind of application is that?

At first we are discussion DMX I/O (there already is a running project 
doing this with the 335x PRUS (on a BeagleBone board).

But this is only sample "virtual peripheral" project with rather low 
demand that easily could be done with "a 1-Euro microcontroller". (and 
in fact we already did this using a PIC33).

But in future we are planning for several kinds of propriety digital 
waveforms that are to be generated or analyzed.

-Michael