RE: HELP with linker script!!!

["Zagorodnev, Grigory" <grigory.zagorodnev@intel.com>]

Hi, Pieter!
You may consider this example: "implicit" linker script contains extra
information to combine user-defined section with default ".data" one,
providing the beginning mark. C program accesses this mark as data
object. 

$ cat main.c
#include <stdio.h>

int my_val __attribute__((section("my_section"))) = 123;
 
extern int my_section_start;
 
int main(){
    printf("%d - %d\n", my_val, my_section_start);
}

$ cat main.script 
SECTIONS
{
    .data : { 
        my_section_start = .;
        *(my_section) 
    }
}

$ gcc main.c main.script 
$ ./a.out

123 - 123


Best regards!
---
Grigory Zagorodnev
Intel Corporation

>-----Original Message-----
>From: binutils-owner@sources.redhat.com [mailto:binutils-
>owner@sources.redhat.com] On Behalf Of Pieter Arnout
>Sent: Thursday, March 31, 2005 4:27 AM
>To: binutils@sources.redhat.com
>Subject: HELP with linker script!!!
>
>I read the the Red Hat manual "Using ld, the GNU Linker", but I'm
>having trouble. Essentially, I'd like to take specific symbols and
>assign them to a memory region, rather than just take a section and
>assign it to a memory region. I can obtain the symbol values and symbol
>type from the objdump or nm output. The only examples offered in the
>manual, however, only define the output sections .bss and .data by just
>assigning everything from the .bss and .data input sections to it:
>
>SECTIONS
>{
>	. = 0x10000;
>	.text : { *(.text) }
>	. = 0x8000000;
>	.data : { *(.data) }
>	.bss : { *(.bss) }
>}
>
>I want some finer control. Does anyone know how I can go about
>ultimately assigning specific symbols (or data structures if you will)
>to a memory region? Should / can I create a section (much like .text,
>.data or .bss above) in the linker script and call it "my_section" and
>assign a list of symbols to "my_section"? Is this how I would go about
>accomplishing what I want? If so do I reference the symbols by name or
>by value when I call them out in the SECTIONS command? How does that
>look like?
>
>Additionally, where do I define the start and end regions of my stack
>and heap? I use .bss for uninitialized variables, .data for initialized
>variables, but how do I reference the beginning and end of stack and
>the beginning and end of heap?
>
>I need answers urgently.
>
>Thanks so much for your help!
>
>Pieter