From mboxrd@z Thu Jan  1 00:00:00 1970
From: carlo.caione@gmail.com (Carlo Caione)
Date: Sat, 24 Mar 2012 16:26:38 +0100
Subject: Query on linker scripts
In-Reply-To: <CAKuUYSw=_zZykPWeTbJsGEYPPSroWK+whm0o5L_PnCManVcrng@mail.gmail.com>
References: <CAKuUYSw=_zZykPWeTbJsGEYPPSroWK+whm0o5L_PnCManVcrng@mail.gmail.com>
Message-ID: <4F6DE7AE.9070808@gmail.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On 24/03/2012 05:43, Vaibhav Jain wrote:
> Hi,
[cut]
> 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 = .;
>      }
> }

I'm not sure if you are OT, anyway...

i.e. they are useful if you want to clear the bss section before execution.

[snippet for ARM proc]
...
	ldr	r2, =_sbss
	b	LoopFillZerobss
/* Zero fill the bss segment. */
FillZerobss:
	movs	r3, #0
	str	r3, [r2], #4

LoopFillZerobss:
	ldr	r3, = _ebss
	cmp	r2, r3
	bcc	FillZerobss
...

--
Carlo Caione