Linker script question

Linker script question

[Johannes Bauer]

Dear all,

I have a question regarding linker scripts. For a certain embedded MCU I 
have 256k of Flash memory and 96k of RAM available:

MEMORY
{
	FLASH (rx)	: ORIGIN = 0x00000000, LENGTH = 256k
	SRAM (rwx)	: ORIGIN = 0x20000000, LENGTH = 96k
}

In the section definition I'd like to define a symbol which signifies 
the end of the SRAM range, i.e.:

	
__ramend = 96k + __data_start__;

(where __data_start__ is laid out so it is starting at 0x2000000, i.e. 
the beginning of the RAM section).

The way I'm doing this currently is by duplicating the "96k" value 
explicitly. However, for easy maintenance it would be nice to have only 
one symbol to change (as many devices in the same family behave exactly 
the same and only the sizes of the memory differs).

I've tried to pass the ramsize to the linker using a define, but this 
worked neither for the MEMORY definition nor for the __ramend definition 
contained within SECTION.

Is there a way to refer to the previously defined LENGTH and ORIGIN 
attributes within the SECTION definition, for example like (pseudo syntax):

__ramend = MEMORY_LENGTH(SRAM) + __data_start__;

Kind regards,
Johannes

Re: Linker script question

[Ian Lance Taylor]

Johannes Bauer <JB.Imm@gmx.de> writes:

> I have a question regarding linker scripts.

Note that linker scripts are a feature of the linker (obviously) and
the linker is not part of gcc.  The linker is part of the GNU
binutils; see http://sourceware.org/binutils/ .


> Is there a way to refer to the previously defined LENGTH and ORIGIN
> attributes within the SECTION definition, for example like (pseudo
> syntax):
>
> __ramend = MEMORY_LENGTH(SRAM) + __data_start__;

As far as I know this is not possible.  I would recommend generating
the linker script through some sort of preprocessor.

Ian