Creating multiple segment for section using linker script

Question

Could anyone please point me out what is the limitation to the alignment value which makes the creation of multiple segment for a section.

With The test case mentioned below:

#include <stdio.h>
#define SIZE (1 << 11)

int Buffer[SIZE]  __attribute__ ((aligned (SIZE * sizeof(int)))) ;

int main (int argc, char * argv[])
{
printf("Test\n");
return 0;
}

And here if i change the macro as:

#define SIZE (1 << 11) to #define SIZE (1 << 12)

Without the above changes we see only two loadable segment while with the above changes we observed three loadable segment. As the alignment of BSS changes from 8K to 16K for GCC 4.8.1 which creates three loadable segments.

So can anyone please tell me what changes need to be done in linker script to make creation of only one loadable segment for data.

This i have observed for i686 machine.

geek
– geek

2016-05-19 09:55:02 +00:00
Commented May 19, 2016 at 9:55 — geek
– geek, Commented May 19, 2016 at 9:55

Ravi · Accepted Answer · 2016-05-25 11:45:21Z

1

There are two ways of creating a linker script: 1. Under ld/emulparam directory there are shell script which creates linker script. 2. While other part of linker script came from the actual source.

Now in the source part there depends which linker you are using ie. GNU linker or gold linker.

answered May 25, 2016 at 11:45

Ravi

291 silver badge8 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

geek · Accepted Answer · 2016-05-26 09:41:17Z

1

GNU Linker script is build based on:

Under directory ~/binutils-2013.11/ld/emulparams/, there are different architecture specifics shell script based on different ELF type and platform like for i386/Vxworks

elf_i386_vxworks.sh

While still the rest of generic contains in the script came from the ld/elf sources.

While about segment creation then please look into procedure **bfd_boolean _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)** under source "bfd/elf.c"

answered May 26, 2016 at 9:41

geek

571 silver badge10 bronze badges

Collectives™ on Stack Overflow

Creating multiple segment for section using linker script

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related