Query on linker scripts

[Vaibhav Jain <vjoss197@xxxxxxxxx>]

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

 

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