Re: copy self from ROM to RAM

[Bernhard Maeder/Alex Raimondi <wearpos at ife dot ee dot ethz dot ch>]

Hi

I'm doing the same thing in my project.

What you have to do is:

Write our own linker script. There you have to deal with LMA (load memory
address) not equal VMA (virtual memory address). How this works you can
find in documentation of gnu-ld (binutils). It's realy helpfull!
In our linkerscript you generate some symbols you can referenc to in your
application.

Write your own startupcode that is copying your code from ROM to RAM.
Therefor you can refernce your linkerscript symbols. After all call your
C main() function.

But take care, there may be another problem: If you havê somewhat like a
mix (some part of the program in ROM running form there, and some part of
the programm running from RAM) function calls may be to far for relative
calls. You have to tell the compiler that he should genearate long calls
(loading new address in a register and transfer it to pc).
Use __attribute__ to do so. Se gcc documentation for more information
about attributes!

alex


On Sat, 2 Feb 2002, Mike Dorin wrote:

>
> I have an application which runs out of RAM, and I can load it
> using GDB or a P&E Microsystems adapter.
>
> What do I have to do have some boot code copy the image from
> ROM to RAM at startup?
>
> Thanks,
> Mike
>
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