ColdFire/68K Microcontrollers and ProcessorsのトピックRe: ROM-RAM copying

ROM-RAM copying

mickael — Thu, 29 Nov 2007 16:52:51 GMT

Hi everybody,

I am working with a coldfire MCF5235.

I have two questions concerning ROM-RAM copying :

1/ I am using the rom-ram copying with the lcf file. This works great. See below my linker file:

# Sample Linker Command File for CodeWarrior for ColdFire

MEMORY
{
user   (RX) : ORIGIN = 0x00000500, LENGTH = 0x0
sdram  (RWX) : ORIGIN = 0x00000000, LENGTH = 0x0
vector_ram (RWX) : ORIGIN = 0x00000000, LENGTH = 0x0
sram  (RWX) : ORIGIN = 0x20000000, LENGTH = 0x0
ext_sram (RWX) : ORIGIN = 0x30000000, LENGTH = 0x0
ipsbar  (RWX) : ORIGIN = 0x40000000, LENGTH = 0x0
ext_flash (RWX) : ORIGIN = 0xFF800000, LENGTH = 0x0
}

SECTIONS
{

.sdram  : {} > sdram
.vector_ram : {} > vector_ram
.ipsbar  : {} > ipsbar
.sram  : {

  . = ALIGN(0x10); #align next section on 16-byte boundary.
          *(.fec_data)
  . = ALIGN(0x10);

        } > sram    #places the section contents at the beginning of the
       #memory segment "sram"
.ext_sram : {} > ext_sram

.boot_flash :
{
  vectors.s (.text)
  mcf523x_lo.s (.text)
  hwinit.c  (.text)
  C_4i_CF_StdABI_Runtime_Sodimas.a (.text)
  .= ALIGN(0x4);

} > ext_flash

__end_of_text = .;

___DATA_ROM  = __end_of_text;

___DATA_RAM = ADDR(user);

.sys_sram : AT(___DATA_ROM)
{
.= ALIGN(0x4);

   *(.text)
  *(.rodata)
  .= ALIGN(0x4);

  __START_DATA = .;
  *(.data)
  __END_DATA = .;

  __START_SDATA = .;
  *(.sdata)
  __END_SDATA = .;

  __SDA_BASE = .;
  .= ALIGN(0x4);
} > user

.uninitialized_data :
{
  __START_SBSS = .;
  *(.sbss)
  *(SCOMMON)
  __END_SBSS = .;

  __START_BSS = .;
  *(.bss)
  *(COMMON)
  __END_BSS = .;

. = ALIGN (0x4);

  ___HEAP_START = .;
  ___HEAP_END  = ___HEAP_START + 0x10000;
  ___SP_END  = ___HEAP_END;
  ___SP_INIT  = ___SP_END + 0x1000;

  .    = ALIGN(0x4);
} >> user

_romp_at = ___DATA_ROM + SIZEOF(.sys_sram);
.romp : AT(_romp_at)
{
  __S_romp = _romp_at;
  WRITEW(___DATA_ROM);
  WRITEW(ADDR(.sys_sram));
  WRITEW(SIZEOF(.sys_sram));
  WRITEW(0);
  WRITEW(0);
  WRITEW(0);
}

___IPSBAR  = ADDR(.ipsbar);
___VECTOR_RAM  = ADDR(.vector_ram);
___SDRAM  = ADDR(.sdram);
___SDRAM_SIZE  = 0x01000000;
___SRAM   = ADDR(.sram);
___SRAM_SIZE  = 0x00010000;
___EXT_SRAM  = ADDR(.ext_sram);
___EXT_SRAM_SIZE = 0x00080000;
___EXT_FLASH  = ADDR(.boot_flash);
___EXT_FLASH_SIZE = 0x00800000;
___heap_addr   = ___HEAP_START;
___heap_size   = 0x10000;
__SP_INIT   = ___SP_INIT;

}

My question is to know when is done the copy of the section "user" from ram to rom. Is it done after the execution of the section boot flash?

2/ My second question is to know if it is possible to have a conditionnal ROM RAM copying.

I would like to specify in the lcf file wether I copy to ramone flash zone or another.

Typically :

if (flag)

copy the flash zone A to RAM

else

copy the flash zone B to RAM

Thanks

Re: ROM-RAM copying

CrasyCat — Thu, 29 Nov 2007 17:38:39 GMT

Hello

1- The copy of the data from ROM to RAM is performed by the startup code.

Basically the startup code is doing the following:

- Disable interrupts

- Initialize stack pointer and diverse registers

- Initialize hardware

- Initialize section bss & sbss to 0

- Copy data from ROM to RAM

- call main

You can look at the code of the startup function in

{Install}\E68K_Support\Runtime\Runtime_68K\Runtime_ColdFire\(Source)\E68k_startup.c

2- There is no way to add conditional code in the linker control file.

The linker file syntax does not provide support for conditional blocks.

CrasyCat

Re: ROM-RAM copying

mickael — Thu, 29 Nov 2007 18:06:33 GMT

Thank you for your quick answer crazy cat! But I still don't catch everything!

1/ I thought the startup code was in mcf523x_lo.s, see below :

/********************************************************************
* This is the main entry point upon hard reset.
*/
asm_startmeup:
_asm_startmeup:

move.w #0x2700,sr

/* Initialize IPSBAR */
move.l #(___IPSBAR + 1),d0
move.l d0,0x40000000

/* Initialize RAMBAR1: locate SRAM and validate it */
move.l #(___SRAM + 0x21),d0
.long 0x4e7b0C05 /* movec d0,RAMBAR1 */

/* Point Stack Pointer into SRAM temporarily */
move.l #(___SRAM + 0x10000),sp

/* Initialize mcf523x periphs, etc */
jsr mcf523x_init

/* Relocate Stack Pointer */
move.l #___SP_INIT,sp

/* Jump to the main process */
/* jmp  _main */
jmp     start

bra  .
nop

nop
/* halt */

What is executed first? mcf523x_lo.s or E68k_startup.c?

2/ So for you, if I want to do my conditionnal ROM-RAM copying, I have to modify E68k_startup.c and recompile it.

Thanks again

Re: ROM-RAM copying

Arev — Thu, 29 Nov 2007 18:49:31 GMT

Hello,

"asm_startmeup" is executed first and "jmp start" jump to E68k_startup code.

I think you have to define different lcf file and target for each configuration you want.

I Hope this helps..

Bye

<< Freescale MCF5234/35 with CodeWarrior 6.2 >>

Re: ROM-RAM copying

mickael — Thu, 29 Nov 2007 20:42:05 GMT

1/ Thank you Arev for you help on boot sequence.

2/ Defining several lcf and several targets is useless for me. I ‘am in the following configuration :

FLASH MEMORY :

Boot zone

Zone A

Zone B

I want to boot on the boot zone and then (considering a flag in the flash) either copy to RAM zone A or zone B. Then I want to boot in RAM.

Thanks