linux-kernel - Re: RFC: kconfig select warnings bogus?

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Message-ID: <a781481a0705191702x269f7f8ev95fd3f9f7c9c1ad4@mail.gmail.com>
Date:	Sun, 20 May 2007 05:32:56 +0530
From:	"Satyam Sharma" <satyam.sharma@...il.com>
To:	"Adrian Bunk" <bunk@...sta.de>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Sam Ravnborg" <sam@...nborg.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Roman Zippel" <zippel@...ux-m68k.org>,
	"Kumar Gala" <galak@...nel.crashing.org>,
	"Simon Horman" <horms@...ge.net.au>
Subject: Re: RFC: kconfig select warnings bogus?

On 5/20/07, Adrian Bunk <bunk@...sta.de> wrote:
> On Sun, May 20, 2007 at 05:11:50AM +0530, Satyam Sharma wrote:
> > On 5/20/07, Satyam Sharma <satyam.sharma@...il.com> wrote:
> >> On 5/20/07, Adrian Bunk <bunk@...sta.de> wrote:
> >> > On Sun, May 20, 2007 at 04:47:52AM +0530, Satyam Sharma wrote:
> >> > > On 5/20/07, Adrian Bunk <bunk@...sta.de> wrote:
> >> > >> On Sun, May 20, 2007 at 04:19:12AM +0530, Satyam Sharma wrote:
> >> > >> >...
> >> > >> > A combined patch for all of those on top of 22-rc2 (adding
> >> > >> Signed-off-by's
> >> > >> > for original authors too):
> >> > >> >...
> >> > >> > --- a/arch/m68k/Kconfig       2007-05-20 04:11:47.000000000 +0530
> >> > >> > +++ b/arch/m68k/Kconfig       2007-05-20 04:23:57.000000000 +0530
> >> > >> > @@ -411,6 +411,7 @@ config STRAM_PROC
> >> > >> >
> >> > >> > config ATARI_KBD_CORE
> >> > >> >       bool
> >> > >> > +     default y if KEYBOARD_ATARI || MOUSE_ATARI
> >> > >> >...
> >> > >> > --- a/drivers/input/keyboard/Kconfig  2007-05-20 04:11:55.000000000
> >> > >> +0530
> >> > >> > +++ b/drivers/input/keyboard/Kconfig  2007-05-20 04:24:54.000000000
> >> > >> +0530
> >> > >> > @@ -167,7 +167,6 @@ config KEYBOARD_AMIGA
> >> > >> > config KEYBOARD_ATARI
> >> > >> >       tristate "Atari keyboard"
> >> > >> >       depends on ATARI
> >> > >> > -     select ATARI_KBD_CORE
> >> > >> >       help
> >> > >> >         Say Y here if you are running Linux on any Atari and have a
> >> > >> keyboard
> >> > >> >         attached.
> >> > >> > diff -ruNp a/drivers/input/mouse/Kconfig
> >> b/drivers/input/mouse/Kconfig
> >> > >> > --- a/drivers/input/mouse/Kconfig     2007-05-20 04:11:55.000000000
> >> > >> +0530
> >> > >> > +++ b/drivers/input/mouse/Kconfig     2007-05-20 04:25:09.000000000
> >> > >> +0530
> >> > >> > @@ -179,7 +179,6 @@ config MOUSE_AMIGA
> >> > >> > config MOUSE_ATARI
> >> > >> >       tristate "Atari mouse"
> >> > >> >       depends on ATARI
> >> > >> > -     select ATARI_KBD_CORE
> >> > >> >       help
> >> > >> >         Say Y here if you have an Atari and want its native mouse
> >> > >> >         supported by the kernel.
> >> > >> >...
> >> > >>
> >> > >> This is a good example how "fixing" the warnings makes things
> >> worse...
> >> > >
> >> > > How?
> >> >
> >> > Consider ATARI_KBD_CORE was used by 20 drivers.
> >> >
> >> > Using select for such not user visible helper variables is a really nice
> >> > thing, and much more readable (and therefore much less likely to contain
> >> > bugs) than dependencies with tons of "||"'s.
> >>
> >> Well, the "default .. if .." kind of idiom is fairly common (I could say
> >> almost standard), in arch/.../config's. It's been used for some time,
> >> and for several symbols over there. But you're right that if 20 drivers
> >> used ATARI_KBD_CORE, we'd get tons of ugly "||"'s there, so
> >> perhaps we do need some kind of fix for this.
> >
> > [ BTW ] I hope nobody gets the wrong message with the word "fix"
> > above, what you're pointing out is only a "readability" issue, not a
> > potential build breakage or any critical problem ...
>
> And what it would "fix" is only a bogus warning, not a potential build
> breakage or any critical problem ...

Yeah, as I said already, if you're saying that all four of these warnings
are bogus and don't lead to any build failures, then perhaps the patch
I sent isn't any "critical" either. Again, I can't really confirm, because
I've never tried to build these drivers, because I don't have access to
powerpc / m68k machines.

But the patch I sent does suppress bogus warnings, and does it in a
way that is fairly common / similar to the way most other similar helper
stuff are handled in arch/.../config's.

Sam's patch will also suppress warnings, but the problem there is that
it kills off checking for "select"ion of non-existent symbols _completely_,
and thus may allow build breakages to occur.
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