Huge difference in build sizes

[Vinícius Tinti]

On Tue, Dec 2, 2014 at 7:08 AM, Raghavendra <arrao at cdac.in> wrote:
> Hello all,
>
> I am using Ubuntu-12.04 which came with 3.2 kernel. Parallel to this,
> I've compiled and installed 3.12.1 kernel using the Ubuntu-3.2's
> configuration, and the compiler which came with the distro. I've noticed
> that there is a huge difference in the size of the .ko file between the
> Ubuntu's kernel and the kernel which I've compiled. Sample results are :
>
> $ du -sh usb-storage.ko
> It shows : 56K for the Ubuntu's 3.2 kernel
>                  1.3M for the custom kernel that I've compiled
>
> I've tested the same thing for a simple hello world module :
> $ du -sh hello.ko
> It shows : 4.0k for the Ubuntu's 3.2 kernel
>                  56k for the custom kernel that I've compiled
>
> What could be the reason for this huge amount of difference of storage
> space in spite of using the same config file and compiler?

Are you sure that you have build with the same optimization flags?

I guess that "-O2" is missing in the big example. Could you double check?

Regards

> Thanks in advance.
>
> Raghavendra
>
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