Re: Regarding linker code generation

[Nick Clifton <nickc at redhat dot com>]

Hi Bhushan,

> Now problem is that we are unable to give the execute permission (RWX) to
> data segment.  This is requirement for  run time linker.

An unusual requirement, but OK...

> Could you please help me how can I do this ,is there any provision to change
> the default linker script.

Yes.  The -T command line switch to the linker (or to gcc) will override the 
default linker script and let you specify your own script.

Here is one way of doing this:

  1.  Run "ld --verbose" and save the output.  This gives you a copy of the 
built-in, default linker script.  You will need to edit the output to remove a 
few lines of text at the beginning and end of the output.

  2.  Read the linker manual's section on linker scripts and in particular the 
part about defining your segments.  Then add a set of segment definitions to 
your new linker script.  For example I used this:

  PHDRS
  {
    exec_data PT_LOAD  FLAGS (7) ;
    code      PT_LOAD  FLAGS (5) ;
    data      PT_LOAD  FLAGS (6) ;
  }

  3. Now you can annotate the entries in the SECTIONS part of the linker 
script with the segment that you want them to use.  eg:

   .rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) } :exec_data

You may need to experiment a bit but you should be able to achieve the results 
you want.

Cheers
  Nick