• State Not Answered
  • Locked Locked
  • Replies 1 reply
  • Subscribers 21 subscribers
  • Views 2191 views
  • Users 0 members are here
2025 survey

We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.

Options
How was your experience today?
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

static data in position independent code on arm

Alexander Polleti

Hello everyone,

I'm a student from germany and am trying to implement position independency (ram and rom) on a STM32F103VF (Cortex™-M3 with MPU), programmed with Keil µVision V4 (full version). I want to write an OS that calls postinstalled Apps that are programed in other µVision projects.

The calling code int the OS looks like this:

  tOSInitFunc initFunc = (tOSInitFunc) (APP_LOCATION);
  thisSb = OS_GetSb();
  OS_SetSb( APP_SB );
  workFunc = (tOSFunc) initFunc();
  OS_SetSb( thisSb );

where

 OS_GetSb( void )

and

 OS_SetSb( u32 )

get and set the static base register r9.

 initFunc( void )

shall initialize the static data and return the adress of a worker function.

My problem is with the initialization part.

Is it possible to adapt the startup code (startup_stm32f10x_hd.s) in the way it uses position independency for initializing my static data? I don't think its that easy to just call __main in the startupfile, is it? Do I have to adapt a __scatterload-function? Is there any useful documentation about this problem (I'm searching for about 4 days now...).

I'm no pro at all and hope my question is not that stupid...

thanks for helping

0