linux-kernel - Re: [RFC] x86: merge nmi

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Message-ID: <483071DE.6010404@firstfloor.org>
Date:	Sun, 18 May 2008 20:13:50 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Adrian Bunk <bunk@...nel.org>
CC:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	Tom Spink <tspink@...il.com>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jiri Slaby <jirislaby@...il.com>,
	Sam Ravnborg <sam@...nborg.org>
Subject: Re: [RFC] x86: merge nmi_32-64 to nmi.c

Adrian Bunk wrote:
> On Sun, May 18, 2008 at 08:25:38AM +0100, Jeremy Fitzhardinge wrote:
>> Thomas Gleixner wrote:
>>> Definitely, but we should do it at the Kconfig level which allows us
>>> to have integer defines as well, so we end up with something like:
>>>
>>> static inline unsigned int get_nmi_count(int cpu)
>>> {
>>>       return CONFIG_X86_64 ? cpu_pda(cpu)->__nmi_count : nmi_count(cpu);
>>> }
>>>   
>> Unfortunately that doesn't work because when CONFIG_X86_64 isn't defined  
>> it doesn't expand to 0.  It would be nice if CONFIG_* expanded to 0/1,  
>> but we'd need to change all the #ifdef CONFIG_* to #if CONFIG_*...
> 
> Even more important:
> How do you want to handle kconfig variables set to "m"?
> 
> Expand them to 0.5 ?  ;-)

The whole idea was pretty bad. Ifdefs are not ugly because the syntax
looks ugly, but because it's a semantically ugly construct with bad
maintainability impact.

Trying to put syntactical sugar around that is a doomed exercise. It
will be still ugly, no matter what you do.

-Andi

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