RE: Query on linker scripts

March 24, 2012


      On 03/24/2012 11:52 PM, Pranay Kumar Srivastava wrote:
...
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From: kernelnewbies-bounces+pranay.shrivastava=hcl.com@kernelnewbies.org [kernelnewbies-bounces+pranay.shrivastava=hcl.com@kernelnewbies.org] On Behalf Of kernelnewbies-request@kernelnewbies.org [kernelnewbies-request@kernelnewbies.org]
Sent: Saturday, March 24, 2012 9:30 PM
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Subject: Kernelnewbies Digest, Vol 16, Issue 29
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Today's Topics:
1. Query on linker scripts (Vaibhav Jain)
    2. Re: Query on linker scripts (Carlo Caione)
----------------------------------------------------------------------
Message: 1
Date: Fri, 23 Mar 2012 21:43:40 -0700
From: Vaibhav Jain<vjoss197@gmail.com>
Subject: Query on linker scripts
To: kernelnewbies@kernelnewbies.org
Message-ID:
         <CAKuUYSw=_zZykPWeTbJsGEYPPSroWK+whm0o5L_PnCManVcrng@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
Recently I have started reading tutorials for writing a small kernel. All
such tutorials mention use of linker scripts. I have
read few articles on linker scritps but I am stuck on one thing. I am
unable to understand the use of defining new symbols in linker scripts.
Using a linker script to arrange different sections in the object file is
understandable but defining symbols which are not referenced anywhere in
the script
is confusing. An example is the use of symbols sbss and ebss in the bss
section as show in the script below
ENTRY (loader)
SECTIONS
{
     . = 0x00100000;
     .text ALIGN (0x1000) :
     {
         *(.text)
     }
     .rodata ALIGN (0x1000) :
     {
         *(.rodata*)
     }
     .data ALIGN (0x1000) :
     {
         *(.data)
     }
     .bss :
     {
         sbss = .;
         *(COMMON)
         *(.bss)
         ebss = .;
     }
}
Please explain how defining such symbols is useful.
Thanks
Vaibhav Jain