how to get memory slot not zeroed

I think you are much better off with elaborate scatter loading.

#pragma arm section zidata = "non_init"

__attribute__ ((zero_init)) data_interface_t    g_data_interface ;

#pragma arm section zidata

and in the scatter file:

RW_DATA_INTERFACE   DATA_INTERFACE_ADDRESS   UNINIT
  {
    DATA_INTERFACE.o (data_interface_section)
  }

A variable must be placed in a zero init section to prevent it from being set to 0.

I think you are much better off with elaborate scatter loading.

#pragma arm section zidata = "non_init"

__attribute__ ((zero_init)) data_interface_t    g_data_interface ;

#pragma arm section zidata

and in the scatter file:

RW_DATA_INTERFACE   DATA_INTERFACE_ADDRESS   UNINIT
  {
    DATA_INTERFACE.o (data_interface_section)
  }

A variable must be placed in a zero init section to prevent it from being set to 0.

I posted a mistake - sorry:

#pragma arm section zidata = "data_interface_section"

__attribute__ ((zero_init)) data_interface_t    g_data_interface ;

#pragma arm section zidata

what is a "scatter file"?

Tamir, since you are in a place totally unknown to an IAR person, please be elaborate with the example.

Erik

I did not know that you are working with IAR.
However, for the RealView toolchain, a scatter file is the linker configuration file - the one that allows you to place just about any program element in a specified location. When you use the options for target dialog, you are basically manipulating the file that is provided by default. For IAR the syntax will be no doubt different. I am sorry I cannot provide an example - I never used IAR before.

I did not know that you are working with IAR.
I am not, but I have till a short while ago been working with IAR and now working with Keil

The code above creates a section called "data_interface_section" and places the variables "g_data_interface" in it. Then, that section can be placed at will using the scatter file:

RW_DATA_INTERFACE   DATA_INTERFACE_ADDRESS   UNINIT
{
  DATA_INTERFACE.o (data_interface_section)
}

RW_DATA_INTERFACE is just a moniker for the execution region that can be found in the .map file.
"DATA_INTERFACE_ADDRESS" can be replaced by a magic number and indicates that location of the object, but in the particular example I have taken advantage of the preprocessor capabilities of the toolchain that can be applied to non-source files as well (use something like

#! armcc -E -I"..\firmware\src" -I"..\bootloader\src" -I"..\..\common\src" -I"..\common\src" -DSCATTER_FILE_PREPROCESSOR

at the top of the scatter file. See linker user manual).
UNINT is a descriptor of the execution region. It is compulsory here for this to work, as the location of the variable in a zero init type section (see definition in previous post).

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