Date: Fri, 2 Jan 2009 10:38:01 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Jaswinder Singh Rajput <jaswinderlinux@gmail.com>
Cc: Bryan Donlan <bdonlan@gmail.com>, Ingo Brueckl <ib@wupperonline.de>,
       linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: x86 (Linux Tiny): configure out support for some processors
Message-ID: <20090102093801.GD1975@elte.hu>
References: <495d2974@wupperonline.de> <3e8340490901012119i40971452q9f938702e58d7532@mail.gmail.com> <3f9a31f40901012159l255b95a8he41a341f36ebc54e@mail.gmail.com>
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* Jaswinder Singh Rajput <jaswinderlinux@gmail.com> wrote:

> On Fri, Jan 2, 2009 at 10:49 AM, Bryan Donlan <bdonlan@gmail.com> wrote:
> > On Thu, Jan 1, 2009 at 3:37 PM, Ingo Brueckl <ib@wupperonline.de> wrote:
> >> Is there any reason why CONFIG_PROCESSOR_SELECT is limited to EMBEDDED only?
> >>
> >> In my desktop pc is one specific cpu only, so I do not need support for the
> >> other processors. Unfortunately, I have no chance to disable the other ones.
> >>
> >> As it is already configurable, why not giving this option to everyone?
> >
> > EMBEDDED is just a switch to enable configuration options related to 
> > removing 'core' features of the kernel to save space. Think of it as a 
> > safety to avoid accidentally turning off something important. Feel 
> > free to switch on EMBEDDED if you want to use CONFIG_PROCESSOR_SELECT 
> > - just enabling EMBEDDED doesn't do anything by itself.
> 
> I think EMBEDDED is a misnomer for using CONFIG_PROCESSOR_SELECT and 
> should be used for more specific to Embedded stuff like for Embedded 
> range of CPUs or Embedded Systems.

i think EMBEDDED is justified in this particular case, as enabling 
CONFIG_PROCESSOR_SELECT allows you to create truly CPU-incompatible 
kernels. Kernels that panic on bootup on contemporary CPUs that happen to 
have a different manufacturer.

The normal CPU selection options (like CONFIG_MCORE2) are more like 
performance and preference hints not hard constraints - those kernels will 
generally still boot fine on most other CPUs as well. (with a few 
common-sense exceptions like booting on truly ancient CPUs, i.e. booting 
an CONFIG_MCORE2 kernel on an i486DX CPU will not work)

	Ingo
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