LPC2138 and linker script

Hi,

I want to initialize global variables from ROM,

my crt0.s is same as :

[...]
start:
_start:
  /* select user mode */
  mrs r0, cpsr
  bic r0, r0, #0x1F  /* clear mode flags */
  orr r0, r0, #0x10  /* set user mode */
  msr cpsr, r0

  /* init stack */
  ldr sp,_Lstack_end

  /* copy data */
_Lcopy_data:
  ldr r0, _Linit_data_start
  ldr r1, _Ldata_start
  ldr r2, _Ldata_end
  cmp r1,r2
  beq _Lzero_bss

  /* copy byte by byte if not aligned */
  tst r0, #0x3
  bne _Lcopy_bytes
  tst r1, #0x3
  bne _Lcopy_bytes
  tst r2, #0x3
  bne _Lcopy_bytes
_Lcopy_words:
  ldr r3, [r0], #0x4
 str r3, [r1], #0x4
  cmp r1,r2
  bne _Lcopy_words
  b _Lzero_bss
_Lcopy_bytes:
  ldr r3, [r0], #0x1
 str r3, [r1], #0x1
  cmp r1,r2
  bne _Lcopy_bytes

  /* zero bss */
_Lzero_bss:
  ldr r0, _Lbss_start
  ldr r1, _Lbss_end
[...]

at present my linker script is :

----------------------------------------------------
__TEXT_START__ = 0x00000400;
__DATA_START__ = 0x40003000;
__STACK_END__  = 0x40004000;


SECTIONS
{
  /* Read-only sections, merged into text segment */

  .text0 0x0:
  {
    *intvec.o(.text)
  }

  .text2 __TEXT_START__ :
  {
    *(.text)
    *(.text.*)
  }

  PROVIDE (__etext = .);

  .rodata   :
  {
    *(.rodata)
    *(.rodata.*)
  }

  /* append .data; it will be copied by crt0 to final __DATA_START__ */
  . = ALIGN(4);
  __INIT_DATA_START__ = .;
  .data __DATA_START__ : AT ( __INIT_DATA_START__ )
  {
    *(.data)
    *(.data.*)
    SORT(CONSTRUCTORS)
  }
  . = ALIGN(4);
  __DATA_END__ = .;

  /* noninitialized data; will be zeroed by crt0*/
  __bss_start__ = .;
  .bss       :
  {
   *(.bss)
   *(.bss.*)
   *(COMMON)
   . = ALIGN(4);
  }
  . = ALIGN(4);
  __bss_end__ = . ;
  PROVIDE (end = .);
}

----------------------------------------------------

how to modify this script for initialize global variables from ROM ?

Thanks a lot .

--
-Stan

You might want to tell us whose linker this is a script for.

TW

"Ted" <tedwood@btinternet.com> a &#4294967295;crit dans le message de
news:e268833f-5cc8-4218-be5e-a13356c21de8@j20g2000hsi.googlegroups.com...
> You might want to tell us whose linker this is a script for.
>
> TW
>


I use GNU ld version 2.16.1 ( arm-elf-ld ).

--
-Stan

Stan wrote:
> Hi,
> 
> I want to initialize global variables from ROM,
> 

The easiest way to do this is to look at the standard crt0.s and linker 
files for your compiler, and base your versions on that.  But the normal 
way to set up a linker file is to have memory areas defined at the top 
of the linker file, and put your .text, .data and .bss output sections 
into the ROM and RAM memory areas as appropriate.  The initialised data 
section is put into "> ROM AT> RAM" (or something similar - now you have 
the hint, you can look up the exact syntax) which sets the link-time 
addresses for data items to a ram address, but puts their contents in 
rom.  You need to be careful to get the init_data_start and data_start 
symbols from the correct area - again, look at the standard linker files 
for examples.

You can also drop all the "copy byte" stuff in your startup routines - 
use . = ALIGN(4) liberally in your linker file, and everything will be 
aligned to 32-bit boundaries.

In article <e268833f-5cc8-4218-be5e-a13356c21de8
@j20g2000hsi.googlegroups.com>, Ted says...
> You might want to tell us whose linker this is a script for.

What script?

Robert

-- 
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