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

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Date:	Mon, 14 Apr 2008 11:11:03 +0200
From:	Jacek Luczak <difrost.kernel@...il.com>
To:	Sam Ravnborg <sam@...nborg.org>
CC:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: pgtable_32.h - prototype and section mismatch fixes

Sam Ravnborg pisze:
> On Mon, Apr 14, 2008 at 10:53:07AM +0200, Ingo Molnar wrote:
>> * Sam Ravnborg <sam@...nborg.org> wrote:
>>
>>>> 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.
>> ah, ok. So i guess this will result in a few isolated cases of __init 
>> annotations added to inline functions - Jacek fixed one such case - but 
>> it should not result in the general spreading of __init annotations to 
>> inline functions, correct? (which i was worried about)
> I do not think so. The need for small isolated inline functions
> in the init paths are minimal and last I did a section mismatch free
> sweep on the kernel it was only few if any inline functions(*) I had
> to annotate.
> 
> (*) Considering only the minimal amount of function that ought
> to be annotated inlined.

There's a lot of inline __init functions already - which, on the other hand
should not result in more of such. Attached you can find grep on tree which
shows all inline __init functions (you won't find my paravirt_pagetable_setup_*
functions in output as I removed __init for test).

Sam, do -fno-inline-functions-called-once could affect
paravirt_pagetable_setup_done? In general there was no section mismatch warning
for this function, but I've annotated it also.

-Jacek



View attachment "inline__init.log" of type "text/plain" (5891 bytes)