[ECOS] C variables in sections

[ECOS] C variables in sections

[will]

   Is there any way to put a C variable in a specific section
without having to initialize it?  I found the following example
for initialed variables:
  char stack[10000] __attribute__ ((section ("STACK"))) = { 0 };

When I leave off the initialization to 0, the variable no longer
appears in the appropriate section.  I have some battery-backed
RAM that should not be cleared on startup.

Thanks,
Will

PS- I'm new to the GCC cross-compiler (so hopefully this mail
 is to the right place..).

Re: [ECOS] C variables in sections

[Robin Kirkham]

On Wednesday, 19 January 2000, will wrote:
> 
>    Is there any way to put a C variable in a specific section
> without having to initialize it?  I found the following example
> for initialed variables:
>   char stack[10000] __attribute__ ((section ("STACK"))) = { 0 };
> 
> When I leave off the initialization to 0, the variable no longer
> appears in the appropriate section.  I have some battery-backed
> RAM that should not be cleared on startup.

You need the initialisation because gcc/gld will only assign *initialised*
data to a specfic section.

However, this data will only be written when the program is *loaded* into
the computer, as opposed to when it is first *run*. This is same as with
the normal initialised data segement (usually called .data). So you can 
avoid overwriting data in your battery-backed RAM by instructing your
program loader *not* to load section STACK (or whatever you called it).

Hope this helps,

Robin Kirkham			CSIRO Manufacturing Science and Technology
Project Engineer		Locked Bag 9, Preston 3072, Australia
robin.kirkham@cmst.csiro.au	Phone: +61 3 9662-7756  Fax: +61 3 9662-7853