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Forum: ARM programming with GCC/GNU tools Introducing section within a section in WinARM GCC tools.


Author: Phani K. (phani)
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Hi,

I am using WinARM GCC tools for compiling, linking the code for LPC2378. 
This worked great until recently, where I need to put some signature in 
LPC2378 at particular location to make it Code read protection.

Earlier my .ld file looks like
{
  ROM (rx) : ORIGIN = 0x00000000, LENGTH = (512k-4k)
  RAM (rw) : ORIGIN = 0x40000000, LENGTH = (32k-32)
}
and with LPC2378 requirement of putting the signature of 0x12345678 at 
location 0x1FC I modified the .ld file as below

MEMORY
{
  ROM (rx) : ORIGIN = 0x00000000, LENGTH = (512k-4k)
  RAM (rw) : ORIGIN = 0x40000000, LENGTH = (32k-32)
  CRP_ROM (rx) : ORIGIN = 0x000001FC, LENGTH = 4
}
SECTIONS
{
  /* place "myArray" inside "m_my_memory" */
  .crpsection :
  {
    . = ALIGN(4);
    KEEP(*(.crpsection*));
    . = ALIGN(4);
  } > CRP_ROM

  /* first section is .text which is used for code */
   .text :
  {
  /* *crt0.o (.text) */           /* Startup code */
  /*KEEP (crp.o(.constdata))*/
  KEEP(*(.vectorg))
  KEEP(*(.RESET))
  KEEP(*(.SWI_HANDLER))
  . = ALIGN(4);
  KEEP(*(.init))             /* Startup code from .init-section */
  *(.text .text.*)           /* remaining code */
  *(.gnu.linkonce.t.*)
  *(.glue_7)
  *(.glue_7t)
  *(.gcc_except_table)
  *(.rodata)                 /* read-only data (constants) */
  *(.rodata*)
  *(.gnu.linkonce.r.*)
  . = ALIGN(4);
  } > ROM

  /***** old:
  .text :
  {
    *crt0.o (.text)
    *(.text)
    *(.rodata)
    *(.rodata*)
    *(.glue_7)
    *(.glue_7t)
  } > ROM

created a crp.c file with content
#define CRP1 0x12345678
__attribute__((section(".crpsection"))) unsigned int const 
Security_Value = CRP1;

and added this makefile
SRC =  $(TARGET).c monitor.c adc.c crp.c

With this I get an error saying
c:/winarm/bin/../lib/gcc/arm-elf/4.1.2/../../../../arm-elf/bin/ld.exe: 
section .crpsection [000001fc -> 000001ff] overlaps section .text 
[00000000 -> 0000b23b]
c:/winarm/bin/../lib/gcc/arm-elf/4.1.2/../../../../arm-elf/bin/ld.exe: 
main.elf: section .crpsection lma 0x1fc overlaps previous sections

Basically I want to reserve memory location 0x1FC for CRP value. This is 
basically putting a section inside a section.

Is it possible to do this way in WinARM - GCC tools sets? Or is there 
any other way to do this? Generally I look at generated .bin file to see 
the signature of 0x12345678 at location 0x1FC.

Any thoughts/ suggestions are helpful :)

With best regards,
Phani.

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