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Date: Fri, 2 May 2008 08:53:04 -0500
From: Josh Boyer <jwboyer@linux.vnet.ibm.com>
To: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: [PATCH] [POWERPC] Fix bootwrapper builds with newer gcc versions
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On Fri, 2 May 2008 08:32:12 -0500
Kumar Gala <galak@kernel.crashing.org> wrote:

> 
> On May 2, 2008, at 7:13 AM, Josh Boyer wrote:
> 
> > On Fri, 2008-05-02 at 03:11 -0500, Kumar Gala wrote:
> >> GCC 4.4.x looks to be adding support for generating out-of-line  
> >> register
> >> saves/restores based on:
> >>
> >> http://gcc.gnu.org/ml/gcc-patches/2008-04/msg01678.html
> >>
> >> This breaks the bootwrapper as we'd need to link with libgcc to get  
> >> the
> >> implementation of the register save/restores.
> >
> > We don't link with libgcc anywhere in the kernel.  Is this going to  
> > have
> > similar impacts for building the vmlinux itself?
> 
> Not by default.  The issue only shows up with -Os.  Not sure if we can  
> build the kernel that way.

We can.  See CONFIG_CC_OPTIMIZE_FOR_SIZE.  That's set in at least
pseries_defconfig and ps3_defconfig.  It's also something I've been
thinking about trying with 4xx.

Seems we need a bit more than just the bootwrapper.

josh