linux-kernel - Re: [PATCH 1/3] powerpc, Makefile: Make it possible to safely select CONFIG_FRAME

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Date:	Sat, 2 May 2009 04:14:43 +0400
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <srostedt@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] powerpc, Makefile: Make it possible to safely
	select CONFIG_FRAME_POINTER

On Sun, Apr 05, 2009 at 11:07:56PM +0200, Sam Ravnborg wrote:
> On Fri, Mar 20, 2009 at 07:44:29PM +0300, Anton Vorontsov wrote:
> > This patch introduces ARCH_HAS_NORMAL_FRAME_POINTERS Kconfig symbol.
> > When defined, the top level Makefile won't add -fno-omit-frame-pointer
> > cflag (the flag is useless in PowerPC kernels, and also makes gcc
> > generate wrong code).
> > 
> > Also move ARCH_WANT_FRAME_POINTERS's help text.
> > 
> > Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
> 
> Hi Anton - sorry for the late feedback.
> 
> 1) The preferred naming for variables that are supposed to be selcted
>    are "HAVE_xxxx".
>    So in this case it would be:
>    HAVE_NORMAL_FRAME_POINTER

OK, will rename.

> 2) I do not really understand the interpretation of normal in this case,
>    can it be more specific?

Normal means that architecture's ABI implies having a framepointer,
we don't need any gcc flags.

I'm not sure if we can name it any better, that is what was
suggested by Steven and I don't have any better variant. ;-)

>    Looking at your patch then if specified we use "-fomit-frame-pointer"
>    in the case where it is set.

No. We specify neither -fomit-frame-pointer, nor we specify
-fno-omit-frame-pointer (because that flag causes gcc to generate
wrong code).

>    So I read it like:
> 
>       If arch has normal framepointer then we omit them - strange?
> 
> 3) Indent in top-level MAkefile for new stuff is generally 8 spaces.
>    Do NOT use tabs as this would confuse make and rener assignmnet non-functional.
> 
> 4) The individual "HAVE_* members should be sorted alphabetically in the arch
>    Kconfig file (which they seldomly are :-( )
> 
> 	Sam

Well, yes. So looking into the Kconfig, I'm quite unsure where
to put it to make it alphabetically correct. Ok, let's put
it after K. ;-)

Thanks!

-- 
Anton Vorontsov
email: cbouatmailru@...il.com
irc://irc.freenode.net/bd2
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