How to expand the `bss`section and fill it zeros when 'objcopy'ing?

How to expand the `bss`section and fill it zeros when 'objcopy'ing?

[PRC]

I want to create a raw binary file from a ELF image. I invoke the command:

mips-elf-objcopy -O binary -j ".text" -j ".data" -j ".bss" my.exe my.bin

But the size of the output `my.bin` is not the sum of sizes of ".text", ".data" and ".bss".
It is the sum of ".text" and ".data", excluding ".bss". 

How can I make objcopy expand the ".bss" section and fill it zeros?

Re: How to expand the `bss`section and fill it zeros when 'objcopy'ing?

[Nick Clifton]

Hi PRC,

> I want to create a raw binary file from a ELF image. I invoke the command:
> 
> mips-elf-objcopy -O binary -j ".text" -j ".data" -j ".bss" my.exe my.bin

Please note that when you are reporting a problem like this, it helps to 
mention which version of the binutils you are using.  Problems which exist in 
older versions of the binutils are often fixed in newer versions.

> But the size of the output `my.bin` is not the sum of sizes of ".text", ".data" and ".bss".
> It is the sum of ".text" and ".data", excluding ".bss". 
> 
> How can I make objcopy expand the ".bss" section and fill it zeros?

By telling it that the .bss section has contents that should be loaded.  Like this:

   mips-elf-objcopy -O binary -j .text -j .data -j .bss \
     --set-section-flags .bss=alloc,load,contents \
     my.exe my.bin

Cheers
   Nick