setting section / variable address

[sd_tom]

I am trying to port some code provided by ST for their Nemo-M1 eval board.   They have build projects for IAR, CooCox, and Keil.  Anyways, in the port i’ve found a section that is compiler specific, and wondering what to do here.   I looked for the general GCC answer and it’s not working either :/

#if defined (IAR_ARM_CM3)
/**
* @brief Flag stored in Flash at address 0x0807F800 in case of IAR.
*/
const uint16_t nErasedFlag @ (FLASH_PARS_ADDR) =0x0300;
#elif defined (KEIL)
/**
* @brief Flag stored in Flash at address 0x0807F800 in case of Keil.
*/
const uint16_t nErasedFlag __attribute__((at(FLASH_PARS_ADDR))) =0x0300;
#elif defined (CooCox)
/**
* @brief Flag stored in Flash at address 0x0807F800 in case of CooCox.
*/
__attribute__ ((section(".SECTION251"))) uint16_t nErasedFlag = 0x0300;
#elif defined(__GNUC__) /* This is my creation I'm working on*/
#define nErasedFlag (*((volatile uint16_t *)FLASH_PARS_ADDR)))
nErasedFlag = 0x0300;
#endif

Any other gotcha’s?  I am starting from the IAR project (since I use that at work) and moving stuff over.  Is there a different one of the above projects that will be closer to GCC to start?

• This topic was modified 9 years, 7 months ago by sd_tom.

[support]

There are 2 ways of achieving this:

An undocumented way that may be broken in the further versions of GCC would look like this:

extern const int nErasedFlag asm("0x0807F800");

A classical “supported” approach would be similar to what CooCox version uses: put the variable into a separate section and modify the linker script to place this section at a given address.

You can read more about this here: http://sysprogs.com/w/forums/topic/bootloader/

[sd_tom]

to follow up, just to not leaving it hanging is arguments to LD FLAGS

-Wl,–section-start=.SECTION251=0x0807F800

vs digging into loader script.

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