Date: Sun, 11 Oct 2009 23:27:57 +0200
From: Sam Ravnborg <sam@ravnborg.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: kernel list <linux-kernel@vger.kernel.org>, linux-kbuild@vger.kernel.org
Subject: Re: 32-rc1: "CROSS_COMPILE changed" message breaks compilation
Message-ID: <20091011212757.GA2768@merkur.ravnborg.org>
References: <20090928175605.GB28514@elf.ucw.cz> <20090928190841.GA12004@merkur.ravnborg.org> <20090928192536.GE28514@elf.ucw.cz>
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On Mon, Sep 28, 2009 at 09:25:36PM +0200, Pavel Machek wrote:
> Hi!
> 
> > > After update to 2.6.32-rc1, I'm getting
> > > 
> > > "Makefile:197: *** CROSS_COMPILE changed from "ccache" to to "ccache ". Use "make mrproper" to fix it up. Stop.
> > > 
> > > Note that the message has typo in it ("to to")... What is worse, the
> > > message triggers even when I try to run make mrproper. Ouch.
> > 
> > The massage is changed in kbuild-fixes.git - but it addresses only ARCH=
> > 
> > As a followup to your other mails:
> > The reason to use "make mrproper" is that when ARCH or CROSS_COMPILE changes
> > you have generally either decided to build for a new architecture or
> > you have changed the way you build the kernel (new toolchain or whatever).
> > So to clean up using "make mrproper" is perfectly justified.
> > 
> > The target group that uses CROSS_COMPILE to enable ccache are using
> > CROSS_COMPILE is a way it is not designed for so they should expect that it
> > is not a perfect match.
> 
> What is the recommended way to run ccache, then?
ccache is a frontend to gcc - so I would have expected
you would use: 

    make CC="ccache gcc"

Or does ccache also benefit ld and as and the other that receive
the $(CROSS_COMPILE) prefix?

	Sam
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