linux-kernel - Re: [PATCH] x86: pgtable_32.h - prototype and section mismatch fixes

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Message-ID: <20080414084127.GA11372@uranus.ravnborg.org>
Date:	Mon, 14 Apr 2008 10:41:27 +0200
From:	Sam Ravnborg <sam@...nborg.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Jacek Luczak <difrost.kernel@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: pgtable_32.h - prototype and section mismatch fixes

On Mon, Apr 14, 2008 at 09:26:45AM +0200, Ingo Molnar wrote:
> 
> * Jacek Luczak <difrost.kernel@...il.com> wrote:
> 
> > paravirt_pagetable_setup_[start,done]() is used by __init 
> > pagetable_init(). Annotate both functions with __init.
> 
> >  #ifndef CONFIG_PARAVIRT
> > -static inline void paravirt_pagetable_setup_start(pgd_t *base)
> > +static inline void __init paravirt_pagetable_setup_start(pgd_t *base)
> >  {
> >  	native_pagetable_setup_start(base);
> >  }
> 
> hm, that's an interesting case: we need those annotations probably 
> because gcc decided to not inline those functions. (this is possible via 
> the new CONFIG_OPTIMIZE_INLINING=y option) Sam, what's your take on 
> that?

gcc uses different heuristics for inlining between the different
versions. Therefore to achieve somehow predictable results I
added -fno-inline-functions-called-once when CONFIG_DEBUG_SECTION_MISMATCH
is enabled.

So in the above case for any normal kernel build we would see that
gcc inlined the above and everything is fine.
But for the CONFIG_DEBUG_SECTION_MISMTCH cases we do not inline and
thus we see that we have a section mismatch.

The rationale was that it is better to annotate a few more functions and
reliable results across gcc versions than it is to see section
mismatch warnings only with older but not newer gcc versions.

	Sam
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