linux-kernel - Re: [patch 4/4] x86: apic_is_clustered_box to indicate unsynched TSC's on multiboard vSMP systems

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Message-ID: <20080321185821.GE6571@elte.hu>
Date:	Fri, 21 Mar 2008 19:58:21 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Ravikiran G Thirumalai <kiran@...lex86.org>
Cc:	Yinghai Lu <yhlu.kernel@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Glauber de Oliveira Costa <gcosta@...hat.com>,
	shai@...lex86.org
Subject: Re: [patch 4/4] x86: apic_is_clustered_box to indicate unsynched
	TSC's on multiboard vSMP systems


* Ravikiran G Thirumalai <kiran@...lex86.org> wrote:

> As for the observation about probing the pci space early during the 
> bootup, we call vsmp_init() much earlier during the bootup, which 
> calls is_vsmp_box(), does the pci probing and caches the result in the 
> flag, as you suggest. So the call in the above diff context does not 
> access the pci config space as is.

ah, i see - indeed - the trick with -1 :-)

my point remains though: if you initialize VSMP in a separate function 
anyway then please move this PCI config space access from is_vsmp_box() 
into vsmp_init() and keep a pure flag return is_vsmp_box(). That way 
there can be no question at all whether there are (or can be) any 
side-effects of that function.

	Ingo
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