Huge difference in build sizes

[greg@kroah.com (Greg KH)]

On Tue, Dec 02, 2014 at 02:38:27PM +0530, Raghavendra 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?

You have not "stripped" the debug symbols from the kernel you built,
which is what Ubuntu does as part of their build process.  I suggest
turning off that kernel configuration option, as it's probably not
needed for your development.

Hope this helps,

greg k-h