how to get memory slot not zeroed

at the top of the scatter file
the noinit CLARLY should work, but does not.
so how do you modify/generate a "scatter file"

eRIK

at the top of the scatter file
the noinit CLARLY should work, but does not.
so how do you modify/generate a "scatter file"

eRIK

Go to "options for target", linker tab, then select "Edit".

from the .scf file

 RW_IRAM2 0x20000200 UNINIT 0x0000FE00  {  ; RW data
    Pic_Etcs.o (+RW)
   .ANY (+RW +ZI)
  }

the +ZI must be it
thus something done elsewhere must be the cause of the zero init
anyone any ideas?

Erik

from various sources I have picked the below up

scatter

; *************************************************************
; *** Scatter-Loading Description File generated by uVision ***
; *************************************************************

LR_IROM1 0x08020000 0x00040000  {    ; load region size_region
  ER_IROM1 0x08020000 0x00040000  {  ; load address = execution address
   *.o (RESET, +First)
   *(InRoot$$Sections)
   .ANY (+RO)
  }
  RW_IRAM1 0x20000000 UNINIT 0x00000200  { ;no init section
        *(NoInit)
   }
  RW_IRAM2 0x20000200 UNINIT 0x0000FE00  {  ; RW data
    Pic_Etcs.o (+ZI +RW)
   .ANY (+RW)
  }
  RW_RAM1 0x68000000 UNINIT 0x00080000  {
    Dortmund_BIOS_ShadowRAM.o (+ZI +RW)
  }
}

LR_IROM2 0x08060000 0x00020000  {
  ER_IROM2 0x08060000 0x00020000  {  ; load address = execution address
    Dortmund_BIOS_LCD.o (+RO)
   .ANY (+RO)
  }
}


C
DWORD dwPuppyMunch __attribute__( ( section( "NoInit"),zero_init) ) ;
DWORD dwPuppyFood __attribute__( ( section( "NoInit")) ) ;

#pragma arm section zidata = "NoInit"
DWORD dwPuppyChow;                        //uninit (in non_init section)
#pragma arm section zidata                //back to default (.bss section)

this is as far as it seems I can get, but all 3 zeroes out :(

Erik

It the varialble "dwPuppyChow" located in the right execution region? Is the execution region itself indeed of type UNINIT?

Try just the dwPuppyMunch, the same approach you have for the scatter file and the attribute for dwPuppyMunch worked for me. You need the zero_init in the attribute to force a small global into a specific segment but I think you might be assigning conflicting attributes by dropping the zero_init in the next line and then using the #pragma.

The confusing part is that even though you tell the linker to UNINIT the segment, zero_init is needed to override the default placement algorithm. The default is to silently put small globals into the normal data segment.

Andrew

DWORD dwPuppyMunch __attribute__( ( section( "NoInit"),zero_init) ) ;
//DWORD dwPuppyFood __attribute__( ( section( "NoInit")) )  ;
DWORD dwPuppyFood  ;

//#pragma arm section zidata = "NoInit"
DWORD dwPuppyChow;                        //uninit (in non_init section)
//#pragma arm section zidata                //back to default (.bss section)

andrew, please do me the favor of checking your reference, the above still initializes dwPuppyMunch

thanx,

Erik

Hi Erik,

The program below, compiled with "use micro-lib", uVision 4.22.22:

#include <stdio.h>
#include <stdint.h>
#include "stm32f10x.h"

int32_t NoInit____zero_init __attribute__( ( section( "NoInit"),zero_init) ) ;
int32_t NoInit __attribute__( ( section( "NoInit")) ) ;
int32_t simpleGlobal;

int main(void)
{
        printf("NoInit-zero_init is %d at %x\n", NoInit____zero_init, (int)&NoInit____zero_init);
        printf("NoInit is %d at %x\n", NoInit, (int)&NoInit);
        printf("simpleGlobal is %d at %x\n", simpleGlobal, (int)&simpleGlobal);

        return 1;
}

prints out:

NoInit-zero_init is 103643149 at 20000004
NoInit is 0 at 20000000
simpleGlobal is 0 at 20000200

using this scatter-load:

LR_IROM1 0x08000000 0x00100000  {    ; load region size_region
  ER_IROM1 0x08000000 0x00100000  {  ; load address = execution address
   *.o (RESET, +First)
   *(InRoot$$Sections)
   .ANY (+RO)
  }
  RW_IRAM1 0x20000000 UNINIT 0x00000200  { ;no init section
        *(NoInit)
   }
  RW_IRAM2 0x20000200 0x00018000  {  ; RW data
   .ANY (+RW +ZI)
  }
}

If you single step in the assembly view before you hit main you'll see that the scatterloader adds code to initialize the NoInit variable but not the NoInit____zero_init variable.

Andrew

thanks a bunch, I'm stuck in meetings for the next 2 days, will report back

Erik