linux-kernel - Re: x86_32_early_logical_apicid() -> one warning per CPU on late-determined BIGSMP systems

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Message-ID: <20110818115921.GA20085@htj.dyndns.org>
Date:	Thu, 18 Aug 2011 13:59:21 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Jan Beulich <JBeulich@...ell.com>
Cc:	mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: Re: x86_32_early_logical_apicid() -> one warning per CPU on
 late-determined BIGSMP systems

Hello,

On Thu, Aug 18, 2011 at 12:54:10PM +0100, Jan Beulich wrote:
> >>> On 12.08.11 at 12:15, Tejun Heo <tj@...nel.org> wrote:
> > Ooh, okay, bigsmp switches apic pretty late in the init.  Wouldn't it
> > be better to move that to right after dmi init regardless of this
> > problem?
> 
> No, because this depends on knowing num_possible_cpus(), which
> in turn can't be done until after the firmware tables got parsed (and
> that's where the ->x86_32_early_logical_apicid() call happens).

OIC, switching apic that late seems rather nasty.  Eh well...  :(

> > So, yeah, please go ahead and remove it.
> 
> There are quite a few references to this, and some from code that
> if I change it I would have no way of testing (Summit, ES7000, NUMAQ).
> So no, I don't think I'm in the position to do this cleanup (if it really is
> just that).
> 
> So for the time being I'll put together a patch re-writing
> early_per_cpu(x86_cpu_to_logical_apicid, ...) right after overriding
> apic_default with apic_bigsmp.

Yeap, sure.  We'll need less invasive for -stable anyway.  I'll kill
the method afterwards.

Thanks.

-- 
tejun
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