linux-kernel - Re: Kconfig no longer outputs a .config with freshly updated defconfigs

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Date:	Sun, 3 Aug 2008 13:07:32 +0300
From:	Adrian Bunk <bunk@...nel.org>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Josh Boyer <jwboyer@...ux.vnet.ibm.com>,
	Roman Zippel <zippel@...ux-m68k.org>,
	linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org
Subject: Re: Kconfig no longer outputs a .config with freshly updated
	defconfigs

On Sun, Aug 03, 2008 at 10:00:19AM +0200, Sam Ravnborg wrote:
> On Sat, Aug 02, 2008 at 10:26:47PM +0300, Adrian Bunk wrote:
> > On Sat, Aug 02, 2008 at 12:03:33PM -0400, Josh Boyer wrote:
> > > I was going through the somewhat tedious task of updating the 4xx
> > > defconfigs today, and I noticed some odd behavior from Kconfig.
> > > Basically, I would do:
> > > 
> > > 	make ppc44x_defconfig
> > > 	make oldconfig
> > > 	<build>
> > > 	cp .config arch/powerpc/configs/ppc44x_defconfig
> > > 	make distclean
> > > 
> > > I did this for a number of configs.  Then I went back and tried to build
> > > ppc44x_defconfig again and I got this result:
> > > 
> > > [jwboyer@...alhost linux-2.6]$ make ppc44x_defconfig
> > >   HOSTCC  scripts/basic/fixdep
> > >   HOSTCC  scripts/basic/docproc
> > >   HOSTCC  scripts/kconfig/conf.o
> > >   HOSTCC  scripts/kconfig/kxgettext.o
> > >   SHIPPED scripts/kconfig/zconf.tab.c
> > >   SHIPPED scripts/kconfig/lex.zconf.c
> > >   SHIPPED scripts/kconfig/zconf.hash.c
> > >   HOSTCC  scripts/kconfig/zconf.tab.o
> > > scripts/kconfig/lex.zconf.c:1628: warning: ‘input’ defined but not used
> > >   HOSTLD  scripts/kconfig/conf
> > > [jwboyer@...alhost linux-2.6]$ make oldconfig
> > > scripts/kconfig/conf -o arch/powerpc/Kconfig
> > > #
> > > # using defaults found in /boot/config-2.6.25.13-104.fc9.ppc64
> > > #
> > > 
> > > There was no .config file present after the initial 'make
> > > ppc44x_defconfig', so it defaulted to using something in /boot.  I'm a
> > > bit baffled here, but that seems to be common to any newly updated
> > > defconfig I've done.
> > > 
> > > Was there a change to Kconfig recently that won't copy the defconfig
> > > file to .config if there are no symbol changes or something like that?
> > 
> > Thanks for your bug report, this should have worked.
> > 
> > @Sam:
> > I've bisected this and it is caused by
> > commit f443d2eccf077afd8a839cc7ed66cc4d520c5f05
> > (kconfig: speed up all*config + randconfig).
> > 
> > Minimal example for reproducing it:
> > 
> > make x86_64_defconfig
> > cp .config arch/x86/configs/x86_64_defconfig
> > rm .config
> > make x86_64_defconfig
> > ls .config
> 
> Thanks Adrian.
> 
> The code has started to check if anything changed
> and if not - then do not write out a new config.
> So in your sample above we would not see any changes
> compared to what we read in autoconf.h so we did nto write
> out a new autoconf.h (and thus no .config).
> 
> The right fix seems to check for .config and for changes
> and in both cases to write a new config.
> 
> Patch below.

This breaks with:

make ARCH=x86 x86_64_defconfig
cp .config arch/x86/configs/x86_64_defconfig
make ARCH=x86 i386_defconfig
make ARCH=x86 x86_64_defconfig

Why can't we simply always write the .config?

> 	Sam
>...

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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