linux-kernel - Re: 2.6.24-git7: section mismatches woes

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Message-ID: <20080130190829.GA25490@uranus.ravnborg.org>
Date:	Wed, 30 Jan 2008 20:08:29 +0100
From:	Sam Ravnborg <sam@...nborg.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.24-git7: section mismatches woes

On Wed, Jan 30, 2008 at 07:50:43PM +0100, Rafael J. Wysocki wrote:
> Hi,
> 
> I get these messages, the majority of which seem to be false-positives:
...
> modpost: Found 35 section mismatch(es).
> To see additional details select "Enable full Section mismatch analysis"
> in the Kernel Hacking menu (CONFIG_SECTION_MISMATCH).
Looking in to these atm.

> 
> and if I compile the kernel with CONFIG_SECTION_MISMATCH, it breaks resuming
> from RAM.

The only functional difference when you enable CONFIG_SECTION_MISMATCH is the
addition of the -fno-inline-functions-called-once to CFLAGS.
So we have some code somewhere that breaks if it is not inlined by gcc.

It would be nice to sort out where.
If you have a rough idea where to look you could use the following trick.
Drop CONFIG_SECTION_MISMATCH and build a kernel.

Then for the file/directory where you think the no-inle makes
a difference do:

# To build the dir/file
rm dir/*.o
make KBUILD_NOCMDDEP=1 KCFLAGS=-fno-inline-functions-called-once dir/
# And then link the kernel
make KBUILD_NOCMDDEP=1

The KBUILD_NOCMDDEP=1 tell kbuild to ignore any commandline differences
so kbuild will not rebuild due to changed gcc flags.

Let me know if you need assistance with this.

	Sam
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