From mboxrd@z Thu Jan  1 00:00:00 1970
From: Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Subject: Re: [PATCH] arch: configuration,
	deleting 'CONFIG_BUG' since	always need it.
Date: Thu, 23 May 2013 10:05:34 +0100
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To: Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
Cc: Linux-sh list <linux-sh-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Catalin Marinas <Catalin.Marinas-5wv7dgnIgG8@public.gmane.org>, Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>, Chen Gang <gang.chen-bOixZGp5f+dBDgjK7y7TUQ@public.gmane.org>, Heiko Carstens <heiko.carstens-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>, "paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org" <paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Michel Lespinasse <walken-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Hans-Christian Egtvedt <egtvedt-BrfabpQBY5qlHtIdYg32fQ@public.gmane.org>, Linux-Arch <linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, uml-devel <user-mode-linux-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>, Yoshinori Sato <ysato-Rn4VEauK+AKRv+LV9MX5uooqe+aC9MnS@public.gmane.org>, Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>, Helge Deller <deller-Mmb7MZpHnFY@public.gmane.org>, the arch/x86 maintainers <x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, "James E.J. Bottomley" <jejb-6jwH94ZQLHl74goWV3ctuw@public.gmane.org>, "mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org" <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Frederic Weisbecker <fweis>

On Thu, May 23, 2013 at 10:40:29AM +0200, Geert Uytterhoeven wrote:
> On Thu, May 23, 2013 at 9:57 AM, Chen Gang <gang.chen-bOixZGp5f+dBDgjK7y7TUQ@public.gmane.org> wrote:
> > -config BUG
> > -       bool "BUG() support" if EXPERT
> > -       default y
> > -       help
> > -          Disabling this option eliminates support for BUG and WARN, reducing
> > -          the size of your kernel image and potentially quietly ignoring
> > -          numerous fatal conditions. You should only consider disabling this
> > -          option for embedded systems with no facilities for reporting errors.
> > -          Just say Y.
> 
> ... It's about reducing memory size on devices where you can't show bug or
> warning messages.

And turning off CONFIG_BUG causes lots of warning messages at compile time
about functions which are returning nothing which shouldn't.

The problem is: trying to fix that _will_ mean the result is a larger
kernel than if you just do the usual arch-implemented thing of placing
an defined faulting instruction at the BUG() site - which defeats the
purpose of turning off CONFIG_BUG.

Therefore, it's better that CONFIG_BUG always be y and we stop kidding
ourselves that it's possible to turn this off and safely save space.