Re: Getting linker script memory info from the code

[Toralf Lund <toralf at procaptura dot com>]

David Brown wrote:

> > Is there any way I can obtain info from the linker script's MEMORY spec
> > from within my code? Are the parameters made available as symbols by the
> > linker or anything?
> >
> > - Toralf
> >
> >    
>
> You can certainly do it if you have your own linker script.  For example,
> you might have something like this in your linker file:
>
> .bss (NOLOAD) :
> {
>  . = ALIGN(0x4);
>  __bss_start = .;
>  *(.shbss)
>  *(.bss)
>  *(COMMON)
>  _end =  ALIGN (0x8);   /* Used by sbrk() as start of heap */
>  __bss_end = _end;
> } > IRam
>
>
> You can then have C code like:
>
> extern unsigned long int __bss_start, __bss_end;
>  
[ snip ]
Wouldn't that just give me the end of size of the program and/or end of 
memory area occupied by it? Not what I'm looking for. What I want is 
parameters like the *total* memory size end-of-RAM etc.

I could PROVIDE() them explicitly, the question was really: Do I have 
to? Or are symbols for e.g. the start and end point of IRam (in your 
example) provided automatically?

If it is still not clear what I mean, consider the following MEMORY 
setup, which might be used with the above example:

MEMORY
{
 IRam (rwx) : ORIGIN = 0x001000, LENGTH = 1M
}

the following PROVIDE would then give me symbols with addresses 
corresponding the start and end point of IRam:

PROVIDE (__ram_start = 0x001000);
PROVIDE (__ram_end = 0x001000+1M);

I'm looking for implicitly defined symbols with the same address as 
__ram_start and __ram_end. Do they exist?

- Toralf





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