[En-Nut-Discussion] Devnut_m3n: Changing the linker stage

[Uwe Bonnes]

Hello,

while the actual requirement in real world may still be different, I see
three prominent situations:
- Run standalone from flash
- Run after a bootloader from flash
- Run from ram when developping

At present each device has a linker script like
stm32f107xC_flash.ld. This linker script hard included stm32f10x_flash.ld.

I proposed to remove the hard include and construct the linker calls like

-L<directory> -Tstm32f107xC.ld {-Tstm32f1_boot.ld} -Tstm32f10x_flash.ld

where:
 stm32f107xC.ld only defines the device specific FLASH0 and RAM0 values
                and a bootloader_offset variable with size 0
 stm32f1_boot.ld eventually redefines the bootloader_offset
 stm32f10x_flash.ld contains the family specific definitions as before
                    and has a bootloader section with the NOLOAD option and
                    the bootloader size before the text section

This way we could keep the needed number of different linker scripts
small. The present approach would need 3 scripts for each device. Maybe
there is even way to define bootloader_offset on the command line.

Any options?

The files would look like

/******************************************************************************
 *
 *  stm32f107xC_flash.ld - linker script for nutos on cotrex-m3 STM32F107xC
 *
 *****************************************************************************/

ENTRY(NutInit)
SEARCH_DIR(.)

"bootloader_offset" = 0x00;

MEMORY
{
    FLASH0 (rx) : ORIGIN = 0x08000000, LENGTH = 256K
    SRAM0 (rwx) : ORIGIN = 0x20000000, LENGTH = 64K
===
/******************************************************************************
 *
 *  bootloader offset
 *
 *****************************************************************************/

"bootloader_offset" = 0x800;
===
/****************************************************************************
 *
 * stm32f10x_flash.ld - linker script include for nutos on cotrex-m3 STM32F series
 *
 *****************************************************************************/

/* PROVIDE (__heap_start = _sheap); */

_ramend = ORIGIN(SRAM0) + LENGTH(SRAM0);

SECTIONS
{
    .bootloader (NOLOAD):
    {
	. = bootloader_offset;
    } > FLASH0

    .text :
    {
...
-- 
Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------