linux-kernel - Re: [PATCH] x86: fully honor "nolapic" (take 2)

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Message-Id: <4970A338.76E4.0078.0@novell.com>
Date:	Fri, 16 Jan 2009 14:09:44 +0000
From:	"Jan Beulich" <jbeulich@...ell.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	<tglx@...utronix.de>, <linux-kernel@...r.kernel.org>,
	<hpa@...or.com>
Subject: Re: [PATCH] x86: fully honor "nolapic" (take 2)

>>> Ingo Molnar <mingo@...e.hu> 16.01.09 14:58 >>>
>
>* Jan Beulich <jbeulich@...ell.com> wrote:
>
>> >>> Ingo Molnar <mingo@...e.hu> 16.01.09 14:42 >>>
>> >
>> >* Jan Beulich <jbeulich@...ell.com> wrote:
>> >
>> >> >>> Ingo Molnar <mingo@...e.hu> 16.01.09 13:45 >>>
>> >> >
>> >> >* Jan Beulich <jbeulich@...ell.com> wrote:
>> >> >
>> >> >> +	if (disable_apic) {
>> >> >> +#ifdef CONFIG_X86_IO_APIC
>> >> >> +		disable_ioapic_setup();
>> >> >> +#endif
>> >> >> +		return;
>> >> >> +	}
>> >> >
>> >> > Shouldnt that #ifdef be avoided by always providing the function - 
>> >> > just it is a NOP inline in the !CONFIG_X86_IO_APIC case?
>> >> 
>> >> That would make for a much bigger patch, since the io_apic.h doesn't 
>> >> (and imo shouldn't) be included without that config option.
>> >
>> >But we are using io-apic functionality in that file, so we should include 
>> >io_apic.h, right?
>> 
>> I don't generally (i.e. when !X86_IO_APIC) think so - anything accessing
>> stuff from io_apic.c is guarded by a similar #ifdef.
>
>and wrongly so - it proliferates ugly #ifdefs and sets us up for build 
>failures like that. Developers cannot be expected to keep every build 
>option in mind - we should provide an as homogenic and kconfig-invariant 
>environment as possible.

I mostly agree here, but think that this ought to be a separate cleanup patch.

Jan

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