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

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Date:	Sun, 20 May 2007 01:23:08 +0200
From:	Adrian Bunk <bunk@...sta.de>
To:	Satyam Sharma <satyam.sharma@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Sam Ravnborg <sam@...nborg.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Roman Zippel <zippel@...ux-m68k.org>
Subject: Re: RFC: kconfig select warnings bogus?

On Sun, May 20, 2007 at 04:47:01AM +0530, Satyam Sharma wrote:
> On 5/20/07, Adrian Bunk <bunk@...sta.de> wrote:
>> On Sat, May 19, 2007 at 11:09:44AM -0700, Andrew Morton wrote:
>> > On Sat, 19 May 2007 17:15:23 +0200 Sam Ravnborg <sam@...nborg.org> 
>> wrote:
>> >
>> > > We see a lot of these lately:
>> > >   GEN     /home/bor/build/linux-2.6.22/Makefile
>> > > scripts/kconfig/conf -s arch/i386/Kconfig
>> > > drivers/macintosh/Kconfig:116:warning: 'select' used by config symbol 
>> 'PMAC_APM_EMU' refers to undefined symbol 'SYS_SUPPORTS_APM_EMULATION'
>> > > drivers/net/Kconfig:2283:warning: 'select' used by config symbol 
>> 'UCC_GETH' refers to undefined symbol 'UCC_FAST'
>> > > drivers/input/keyboard/Kconfig:170:warning: 'select' used by config 
>> symbol 'KEYBOARD_ATARI' refers to undefined symbol 'ATARI_KBD_CORE'
>> > > drivers/input/mouse/Kconfig:182:warning: 'select' used by config 
>> symbol 'MOUSE_ATARI' refers to undefined symbol 'ATARI_KBD_CORE'
>> > >
>> > >
>> > > Do this warning really add any value or should we just ignore them 
>> like this?
>> > >
>> >
>> > They always indicate Kconfig bugs, don't they?  If so, we should keep 
>> the
>> > warning.
>> >...
>>
>> No, they aren't always.
>>
>> Look for example at the last one in drivers/input/mouse/Kconfig:
>>
>> config MOUSE_ATARI
>>         tristate "Atari mouse"
>>         depends on ATARI
>>         select ATARI_KBD_CORE
>>
>> This is perfectly correct (the select'ed symbol is only unavailable when
>> the dependency can't be fulfilled), and all things to "fix" the warning
>> will make it worse.
>
> Not sure what you mean here. The select'ed symbol here is unavailable
> because not all arch's define it. However, the symbol that selects it is
> in drivers/input/... and hence run for all arch's. That's the simple issue
> here that is resolved by this fix.

This is OK, because when the select'ed symbol is not available, the 
dependencies can't be fulfilled.

There is no issue here that needs to be fixed.
And that's exactly what Sam's patch is about.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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