netdev - Re: [PATCH] realtek: rtl8xxxu: Use const init arrays

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Date:   Sat, 01 Oct 2016 13:00:58 -0700
From:   Joe Perches <joe@...ches.com>
To:     Jes Sorensen <Jes.Sorensen@...hat.com>
Cc:     Kalle Valo <kvalo@...eaurora.org>, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] realtek: rtl8xxxu: Use const init arrays

On Sat, 2016-10-01 at 14:53 -0400, Jes Sorensen wrote:
> Joe Perches <joe@...ches.com> writes:
> > Make the init arrays const to reduce data.
> > $ size drivers/net/wireless/realtek/rtl8xxxu/built-in.o* (allyesconfig: x86-32)
> >    text	   data	    bss	    dec	    hex	filename
> >   80107	  13651	     58	  93816	  16e78	drivers/net/wireless/realtek/rtl8xxxu/built-in.o.new
> >   65303	  28435	     58	  93796	  16e64	drivers/net/wireless/realtek/rtl8xxxu/built-in.o.old
> In total you grow the kernel by 20 bytes. You reduce the data segment
> substantially while growing the text segment instead.

No, not really.   The alignment boundaries move a bit for
this particular compilation.  It could go the other way for
a different compiler version or set of CONFIG options.

What's important is multiple pages of .data move to .rodata.