[ECOS] Run Time Loader (without RedBoot)

[ECOS] Run Time Loader (without RedBoot)

[Guilly A]

Hi,
I'm moving from pSos to eCos. There was a very usefull feature in pSos that 
I can't find in eCos, which is the run time loader.
In know that RedBoot can load images from flash to it's RAM location, but I 
don't want to use RedBoot, and I need to load a relocatable image, i.e. a 
location-independent image.
Actually, my system is composed of 2 parts :
- 1rst part, the "Bios", wich includes eCos and some drivers to the hardware 
of our card
- 2nd part, the "Application", wich make use of the bios to access the 
hardware features.
I want first to run the Bios, initialize my hardware, then load the 
application in RAM to be executed.
But I would like to be able to load this application anywhere int the RAM, 
where there is some place left actually, which is not know at link time of 
the application. I want to keep the Application as much independent as 
possible of the Bios version.
I'm sure somebody has already encoutered this problem, but I did not find 
any post about it, and I run out of keyword to get some help through Google.
Thank you for your help
Guilly

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Re: [ECOS] Run Time Loader (without RedBoot)

[Guilly A]

Hi Steve,
Thank you for your response, but I am not exacly in this case.
Actually, the Bios part will always be running, and the application will be 
running on top of that.
I can manage to have the bios copying the Application from the Flash to the 
RAM, at a fixed and previously known RAM address. But this limit my 
architecture to be splitted forever with a bios RAM zone and an application 
RAM zone, that can not have theire size/location changed in the future.
This is what I want to avoid, as the bios tends to get bigger and bigger, 
and overlap the application zone wich seems to be oversized (for now) for 
the application.
But my question was, more precisely, does a kind of run time loader exist 
under eCos, or does eCos provides facilities to handle position-independent 
code? It becomes clearer that it does not. I have to think about another 
solution.
Regards,
Guilly


>From: Steve Strublic <SStrublic@Hypercom.com>
>To: guilly_work@hotmail.com
>Subject: Re: [ECOS] Run Time Loader (without RedBoot)
>Date: Thu, 16 Jun 2005 08:57:53 -0700
>
>
>
>
>
>Hi Guilly,
>
>We did run into a very similar scenario, where we wanted the device to boot 
>without Redboot, and
>then be replaced by the application.  What we did was create a minimal eCos 
>'loader' application (no
>Ethernet, no serial support, with flash support) that pretty much only knew 
>how to access flash.  We
>built our run-time application as a RAM image, located at address 0, and 
>loaded the image from flash
>to address 0.  Once loaded, the application was started, and voila!
>
>The loader was a reasonably small size (under 80k), and you could probably 
>trim that down some.  And
>as you desire, the application was completely independent of the loader.  
>All drivers were included
>in the application, as the loader was no longer in existence when the app 
>was running.
>
>I don't think you'll have much luck with a position-independent image in 
>eCos, but then again I've
>never tried to actually build one.
>
>HTH,
>
>Steve
>
>--------
>
>"2 is not equal to 3 - not even for very large values of 2." -- Grabel's 
>Law
>
>
>
>
>              guilly_work@hotmail.com
>              Sent by:
>              ecos-discuss-owner@ecos.sou                                   
>                       To
>              rceware.org                         
>ecos-discuss@sources.redhat.com
>                                                                            
>                       cc
>
>              06/16/2005 07:10 AM                                           
>                  Subject
>                                                  [ECOS] Run Time Loader 
>(without RedBoot)
>
>
>
>
>
>
>
>
>
>
>Hi,
>I'm moving from pSos to eCos. There was a very usefull feature in pSos that
>I can't find in eCos, which is the run time loader.
>In know that RedBoot can load images from flash to it's RAM location, but I
>don't want to use RedBoot, and I need to load a relocatable image, i.e. a
>location-independent image.
>Actually, my system is composed of 2 parts :
>- 1rst part, the "Bios", wich includes eCos and some drivers to the 
>hardware
>of our card
>- 2nd part, the "Application", wich make use of the bios to access the
>hardware features.
>I want first to run the Bios, initialize my hardware, then load the
>application in RAM to be executed.
>But I would like to be able to load this application anywhere int the RAM,
>where there is some place left actually, which is not know at link time of
>the application. I want to keep the Application as much independent as
>possible of the Bios version.
>I'm sure somebody has already encoutered this problem, but I did not find
>any post about it, and I run out of keyword to get some help through 
>Google.
>Thank you for your help
>Guilly
>
>_________________________________________________________________
>Vidéoconférence plein écran avec MSN Messenger http://g.msn.fr/FR1001/866
>
>
>--
>Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
>and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
>
>
>

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RE: [ECOS] Run Time Loader (without RedBoot)

[Paul D. DeRocco]

> From: Guilly A
>
> Actually, the Bios part will always be running, and the
> application will be
> running on top of that.
> I can manage to have the bios copying the Application from the
> Flash to the
> RAM, at a fixed and previously known RAM address. But this limit my
> architecture to be splitted forever with a bios RAM zone and an
> application
> RAM zone, that can not have theire size/location changed in the future.
> This is what I want to avoid, as the bios tends to get bigger and bigger,
> and overlap the application zone wich seems to be oversized (for now) for
> the application.
> But my question was, more precisely, does a kind of run time loader exist
> under eCos, or does eCos provides facilities to handle
> position-independent
> code? It becomes clearer that it does not. I have to think about another
> solution.

Some work has been done on this, but not finished. There's some stuff in
services/loader, but it's incomplete. eCos really wasn't designed with this
capability in mind. It has no run-time symbol table for resolving references
in the loaded app, so one would have to implement that or rig up a sofware
interrupt interface and thunk functions in the application. Also, one would
have to figure out how to get GDB to adapt to the actual load location, if
you wanted to debug your application.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com


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