Date: Wed, 7 Nov 2007 01:12:00 +0100
From: Adrian Bunk <bunk@kernel.org>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>,
       Thomas =?utf-8?Q?B=C3=A4chler?= <thomas@archlinux.org>,
       Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org,
       linux-kbuild <linux-kbuild@vger.kernel.org>
Subject: Re: 2.6.24-rc1-82798a1 compile failure (x86_64)
Message-ID: <20071107001159.GR26163@stusta.de>
References: <fg5kar$d70$1@ger.gmane.org> <alpine.LFD.0.9999.0710292310040.3186@localhost.localdomain> <47266BF6.6070206@archlinux.org> <alpine.LFD.0.9999.0710300033470.3186@localhost.localdomain> <4726F510.9060207@archlinux.org> <472C47B4.4030808@archlinux.org> <20071103121149.GA22149@uranus.ravnborg.org> <20071104020217.GJ12045@stusta.de> <20071106093223.7e6f4f6c@laptopd505.fenrus.org>
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On Tue, Nov 06, 2007 at 09:32:23AM -0800, Arjan van de Ven wrote:
> On Sun, 4 Nov 2007 03:02:17 +0100
> Adrian Bunk <bunk@kernel.org> wrote:
> 
> > On Sat, Nov 03, 2007 at 01:11:49PM +0100, Sam Ravnborg wrote:
> > > On Sat, Nov 03, 2007 at 11:04:36AM +0100, Thomas Bächler wrote:
> > > > Thomas Bächler schrieb:
> > > > > 
> > > > > I just remembered, a friend of mine got it to compile with the
> > > > > exact same toolchain, but with a different configuration (which
> > > > > I don't have). He used a snapshot tarball from yesterday
> > > > > though, not the git tree.
> > > > > 
> > > > 
> > > > I found the problem and eliminated it. While this is my own
> > > > fault, it is still a bug in either the kernel or the build
> > > > system: I had CFLAGS set to "-Wall -O3 -march=native -pipe". I
> > > > always thought the kernel would ignore those and set its own
> > > > CFLAGS, but I was wrong. Either the -O3 or the -march=native
> > > > break the build process on gcc 4.2.2.
> > > > 
> > > The kernel will now honour the users CFLAGS setting as you just
> > > discovered. The flags will be appended to the flags specified by
> > > the kernel.
> > >...
> 
> I think we can solve a ton of issues if we don't make the CFLAGS
> *append* but just *prepend*. That way, if the KConfig overrides a
> certain CFLAG, that sticks... since gcc picks the last one in case of
> conflicting options. That gives us both the honoring of cflags, and the
> principle of least surprise in that KConfig options are honored...

CFLAGS="-I/usr/include -I/usr/local/dist/include"

I think the solution with KCFLAGS that is in 2.6.24-rc2 is the best one.

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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