Re: Linker script

[Thierry Moreau <Thierry dot Moreau at Connotech dot com>]

Daniel Lidsten wrote:

> Hi,
>
> I have a special problem that has to do with the linker script. In my
> application i want to add a CRC value to the binary image so that i can
> check the code segment for errors during runtime. I cannot put the CRC
> over the entire image since some segment are changing during execution
> so instead i want to calculate it based on the text segment only.
> However, the segment is of different size each time i link which means
> that i have to communicate the size to the CRC calcualtion routine. I
> think that it should be done in the linker script by something like
> this:
>
>     .text   0x5000  :      { _stext = .; *(.text*) *(.gnu.warning)
> *(.gnu.linkonce*) *(.init) } >  ram  _etext = .;  PROVIDE
>
> The text segment specifies where the end is in the variable _etext.
>
> I need the above value to be place on a fixed location by something like
> this:
>
> .TextEnd   0x004DFFFC :      { etext }
>
> The above dones work but can any see a way for this to work?
>
> Regards, Daniel Lidsten
>
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Your special problem does not appear so special to me. It is common to require a
CRC of selective linker sections. As a general solution, the linker script
language associated with compiler conventions (which code goes into which
section), **plus an .elf format parser utility** is likely to do the job. The
CRC calculation routine is in the .elf parser utility, and the CRC verification
routine is within the program/system startup sequence. The .elf parser utility
can easily recoginze the length of any program section.

Perhaps you can solve your problem with a simpler solution, see the linker
script excerpt below.

If you are patient, the solution under development for the ABCD Proto-Kernel
should be available as an example (under the GPL license).

--

- Thierry Moreau

CONNOTECH Experts-conseils inc.
9130 Place de Montgolfier
Montreal, Qc
H2M 2A1

Tel.: (514)385-5691
Fax:  (514)385-5900

e-mail: thierry.moreau@connotech.com


/****************************************/
/* Load image sections in the Flash memory. */

/* - - - - - - - - - - - - - - - - - - - */
/* Flash memory contents located here due to execution prior to memory subsystem
initialization */

 . = ( (~(1M-1))+7*128K ) ;
  .reset_follow_up :  { LONG(start_of_flash_segments_desc) /* <<<<<<<<<<<<< */
                        LONG(nb_flash_segments_desc) /* <<<<<<<<<<<<< */
                        *(.reset_follow_up) . = ALIGN(4); } :flash_memory

  .flash_text :
  {
    abcd_init_c1.o(.text .stub .text.*)
    ppcmb850_pio_debug.o(.text .stub .text.*)
    abcd_init_c2.o(.text .stub .text.*)
    crc_1632_init.o(.text .stub .text.*)
    crc_1632.o(.text .stub .text.*)
  abcd_flash_pic_fncs.o(.text .text.* .rodata)

/* - - - - - - - - - - - - - - - - - - - */
/* Flash memory contents located here due to ther explicit selection (e.g. code
used only once) */

    *(.flash_text)
  . = ALIGN(4); } :flash_memory




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