Date: Wed, 6 Jan 2010 11:48:23 +0100
From: Sam Ravnborg <sam@ravnborg.org>
To: Artem Bityutskiy <dedekind1@gmail.com>, Michal Marek <mmarek@suse.cz>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: sections mismatch detection
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On Wed, Jan 06, 2010 at 12:11:23PM +0200, Artem Bityutskiy wrote:
> Hi,
> 
> I wonder is it good time to enable DEBUG_SECTION_MISMATCH by default
> now? I mean, remove the following from lib/Kconfig.debug:
> 
> config DEBUG_SECTION_MISMATCH
>         bool "Enable full Section mismatch analysis"
>         depends on UNDEFINED
>         # This option is on purpose disabled for now.
>         # It will be enabled when we are down to a resonable number
>         # of section mismatch warnings (< 10 for an allyesconfig build)
> 
> Just spotted this, and decided to remind.

My original criteria for enabling this was that we had a warnign free build
for all*config on x86 and a few other architectures.
While focusing on this I never reached this goal as I usually ended
up with some problems related to CPU hotplug.
I dunno how close we are today at the "zero warning" target.

When people implemented CPU hotplug they started to use __cpuinit
not only for code used during init time but also for code used
solely for CPU hotplugging. That made it difficult to solve
all the corner cases.
Because __cpu* annotation was used outside the original scope
I suggested to remove them from the checks but alas got no response.
Running out of time I gave up.

But I can see a steady flow of section mismatch fixes so I think the
situation looks better these days.

As the kbuild maintainer traditionally has been a central person
in this respect (due to the functionality in modpost),
I would like Michal to support this if we decide to enable the option.

	Sam
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