From: Nigel Cunningham <ncunningham@cyclades.com>
Organization: Cyclades Corporation
To: Ashok Raj <ashok.raj@intel.com>
Subject: Re: [rfc] fix Kconfig, hotplug_cpu is needed for swsusp
Date: Thu, 30 Mar 2006 09:36:16 +1000
User-Agent: KMail/1.9.1
Cc: Andrew Morton <akpm@osdl.org>, Pavel Machek <pavel@ucw.cz>,
       linux-kernel@vger.kernel.org
References: <20060329220808.GA1716@elf.ucw.cz> <20060329144746.358a6b4e.akpm@osdl.org> <20060329150950.A12482@unix-os.sc.intel.com>
In-Reply-To: <20060329150950.A12482@unix-os.sc.intel.com>
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Hi.

On Thursday 30 March 2006 09:09, Ashok Raj wrote:
> On Wed, Mar 29, 2006 at 02:47:46PM -0800, Andrew Morton wrote:
> > Pavel Machek <pavel@ucw.cz> wrote:
> > > HOTPLUG_CPU is needed on normal PCs, too -- it is neccessary for
> > > software suspend.
> >
> > OK, this will get ugly.  APICs are involved.
>
> I guess you need only on systems that support >1 cpu right? I doubt you
> will need it on a system that cannot run with the config-generic-arch on.
> although we use bigsmp when hotplug is turned on, all we really end up is
> using flat physical mode instead of using logical mode.
>
> I still havent understood why this wont work. Choosing
> CONFIG_X86_GENERICARCH shouldnt break anything AFAICT.
>
> Pavel, you could use CONFIG_HOTPLUG_CPU, just need to enable
> X86_GENERICARCH now. Is there a reason you think that wont work? I wish we
> would revert it for a strong reason that we know will not make hotplug wo=
rk
> on certain systems because of this choise not that we currently have X86_=
PC
> now, and are unwiling to change the config.
>
> (PS: the word bigsmp although sounds like some large NR_CPUS, its just
> using a mode that permits the system to work from 1 .. >8 cpus. So there =
is
> really nothing determental to selecting this.)

So if you have a single core x86, you want X86_PC, and if you have HT or SM=
P,=20
you want GENERICARCH? If so, could this be done via selects or depends or a=
t=20
least defaults in Kconfig?

Regards,

Nigel

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