[ECOS] eCosCentric Cortex-M port contribution

simon.kallweit@intefo.ch simon.kallweit@intefo.ch
Wed Oct 8 12:07:00 GMT 2008


Nick Garnett wrote:
>> Could you give us some more information about the issues? Also, are
>> there plans to get the patches into the mainline GCC?
>>     
>
> Unfortunately the details are covered by various NDAs between us,
> CodeSourcery and ARM. Once the problem is confirmed by ARM then I
> expect CodeSourcery will update their release, and this will find its
> way into the FSF sources at some point. In the meantime we are looking
> at making a temporary fix for the toolchain that will go out with
> 3.0. Although we will pre-release it when the Cortex-M contribution is
> made.
>   

Ok, I guess the issues you're talking about are not related to the 
silicon errata just release by STMicroelectronics, concerning some 
compilers generating incompatible code with all but the latest revisions 
of the STM32 processors?

>>> All of this is in hand but not quite yet ready for contribution: the
>>> toolchain work needs completing, and we want to get a few runs in on
>>> the test farm to ensure there are no obvious problems before
>>> contributing.
>>>
>>> I expect this to take a couple of weeks more.
>>>
>>>       
>> Now, that puts me in quite an akward situation, as I've been working
>> on a community cortex-m3 port for almost a month now. I wonder if it
>> is best to stop my efforts and wait for your contribution. As we just
>> got the first prototypes of our new STM32 based design a few days ago,
>> we really look forward to get ecos working on the boards, so I cannot
>> really just sit here and wait for your release. Is there a possibility
>> to get the current snapshot upfront so I can continue with development
>> based on your port, and see if there is anything worth to be
>> contributed from the community port? I'd rather put further efforts
>> into your port, if it is the better base for the future.
>>     
>
> We don't want to give free public early access at present. There are
> still a number of thing that need completing before we are ready for
> the world to see it.
>
> You should probably wait. I know that you have just started looking at
> interrupts and context switching. My experience is that this is the
> hardest part of getting this architecture working. ARM's view of how
> operating systems should work is somewhat at odds with how eCos works
> and the harware rather strictly enforces ARM's world view. It is
> unlikely that you will get your port running before we make our
> contribution.
>   

It occurred to me, now that I have been digging into the subject more 
deeply, that there are some issues concerning the design of the 
Cortex-M3 to match with ecos. I think I do understand the design of how 
a kernel should work under the Cortex-M3 architecture, but admittedly I 
don't quite see yet how to do that efficiently with ecos. Does your 
solution come with changes in the generic ecos kernel code, or did you 
manage to solve it all in the Cortex-M3 HAL?

Of course, it might make more sense to just wait for you to release the 
port, but this puts us on hold for an uncertain amount of time, as you 
don't make a clear statement of when the release will be. So I think it 
would be great to start working with your port, as I guess it's pretty 
sure that even if I continue developing and get a working solution 
myself, it will be your port that ends up in the official ecos community 
repository. So my past and future work will be quite obsolete, despite 
the learning I did :(

Is there anything we can do about that? Otherwise, I think I'll continue 
with my development, risking to throw it all away a few weeks from now.

Best regards,
Simon


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