linux-kernel - Re: Reducing debuginfo size by removing unneeded includes

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Date:	Mon, 18 Feb 2008 15:01:13 +0100
From:	Sam Ravnborg <sam@...nborg.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: Reducing debuginfo size by removing unneeded includes

On Mon, Feb 18, 2008 at 02:12:01PM +0100, Andi Kleen wrote:
> Arnaldo Carvalho de Melo <acme@...hat.com> writes:
> >
> > [acme@...pio net-2.6]$ l /tmp/sys_ia32.o.before /tmp/sys_ia32.o.after
> > -rw-rw-r-- 1 acme acme 185240 2008-02-06 19:19 /tmp/sys_ia32.o.after
> > -rw-rw-r-- 1 acme acme 248328 2008-02-06 19:00 /tmp/sys_ia32.o.before
> >
> > 	Almost 64KB only on this object file!
> 
> Just FYI, newer gcc does this in theory automatically when you specify 
> 
> -feliminate-unused-debug-types -feliminate-unused-debug-symbols
> 
> But in my tests on gcc 4.1 / gcc 4.2 it doesn't seem to make any difference
> currently :/ Not sure what is wrong. 
> 
> There is also -feliminate-dwarf2-dups, but it seems to even increase
> obj dir size. Also -feliminate-dwarf2-dups seems to generate a lot of 
> 
> WARNING: vmlinux.o (.gnu.linkonce.wi.mmzone.h.97561702): unexpected section name.
> The (.[number]+) following section name are ld generated and not expected.
> Did you forget to use "ax"/"aw" in a .S file?
> Note that for example <linux/init.h> contains
> section definitions for use in .S files.

Newly introduced consistency check. It immediately catched a few bugs
here and there not othing seriously. We could either restrict it to
known section names or just drop it again. At least it should not
be the reason to avoid using some good gcc feature.

	Sam
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