[ECOS] strange size issue (i386 vs ARM)

[Simon Kallweit]

Mandeep Sandhu wrote:
> Hi Guys,
> 
> I have this strange size issue with my app. I was testing my app with
> the Linux Synthetic target and things work fine. The app does not
> utilize any hardware specific feature, rather just relies on the
> availability of 2 network interfaces to do its job (it's lwIP 1.3.1
> from Simon).
> 
> Now, I want to finally run this app on my AT91SAM7X512 based board. So
> I did a size comparison to see if it'll fit in the boards memory
> (128KB).
> 
> I compiled my app with ecos configured for the at91sam7xek target.
> 
> $ arm-eabi-size myapp
>    text	   data	    bss	    dec	    hex	filename
>  127168	   5940	  45092	 178200	  2b818	myapp
> 
> From this it seems bss + data will fit fine in the 128KB of RAM that I
> have on the board.
> 
> Look at the size output for the _same_ app compiled with the Linux
> Synthetic target:
> 
> $ i386-elf-size myapp
>    text	   data	    bss	    dec	    hex	filename
>  103690	   7328	8381268	8492286	 8194fe	myapp
> 
> The text size of the ARM binary (~127KB) is understandably larger than
> the i386 one (~102 KB).
> 
> But how come the data+bss value is so different!?!? The i386 one is
> more than 8MB!
> 
> Is this expected? I'm still googling to find the answer.

Use objdump -t [filename] to get finer grained information where your 
memory is used. Synth for example uses bigger stacks. But I don't quite 
get myself where all that bss memory is going :)

May someone enlighten us?

Simon

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