[ECOS] Re: RAM vs. ROMRAM question

[Grant Edwards <grante at visi dot com>]

On 2006-10-29, Andrew Lunn <andrew@lunn.ch> wrote:
> On Sun, Oct 29, 2006 at 11:01:30PM +0000, Grant Edwards wrote:
>> I just build RedBoot for both RAM and ROMRAM startup for the
>> Altera NIOS2 platform.  I looked at the section headers for the
>> resulting redboot.elf files, and they're basically the same.
>> 
>> The VMA and LMA for text/data sections are in RAM for both
>> version. Shouldn't the text/data LMA address for ROMRAM startup
>> be in ROM?
>
> No, i don't think so. If you were using a run time loader which was
> actually interpreting the header and loading the code into the correct
> place it might matter, but with ROMRAM starrup the eCos HAL itself is
> doing the copy from ROM to RAM and the addresses are hard coded into
> the image. The start code which does the copy is position independent,
> or at least aware its not running where it was linked to run and so
> can take the appropriate action.

I see. So a hex file generated from a ROMRAM elf won't have the
correct load addresses in it unless the user offsets them when
generating the hex file?

I also noticed that ecosconfig gets upset if I try to make
RedBoot a "ROM Monitor" when it's configured for RAM startup.

What does being a "ROM Monitor" have to do with startup mode?
Shouldn't Redboot be able to provide services to applications
either way?  In both cases it's running from RAM, so I don't
see why the distinction is made.

-- 
Grant Edwards                   grante             Yow!  Yow!! That's a GOOD
                                  at               IDEA!! Eating a whole FIELD
                               visi.com            of COUGH MEDICINE should
                                                   make you feel MUCH BETTER!!


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