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Date: Sat, 5 Mar 2011 08:50:33 +0100
From: Tejun Heo <tj@kernel.org>
To: David Rientjes <rientjes@google.com>
Cc: Yinghai Lu <yinghai@kernel.org>, Ingo Molnar <mingo@elte.hu>,
        tglx@linutronix.de, "H. Peter Anvin" <hpa@zytor.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH x86/mm] x86-64, NUMA: Don't assume phys node 0 is
 always online in numa_emulation() handling
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On Fri, Mar 04, 2011 at 01:33:29PM -0800, David Rientjes wrote:
> On Fri, 4 Mar 2011, Tejun Heo wrote:
> 
> > Undetermined entries in emu_nid_to_phys[] are filled with zero
> > assuming that physical node 0 is always online; however, this might
> > not be true depending on hardware configuration.  Find a physical node
> > which is actually online and use it instead.
> > 
> 
> I still don't understand why emu_nid_to_phys[] can't return NUMA_NO_NODE 
> and this needs to be done at all.  An emulated node should be mapped to a 
> physical node based on the address ranges of that emulated node, so it's 
> impossible for that to not map directly to a physical online node.  We 
> don't support memoryless emulated nodes for hotpluggable SRAT entries.

Me neither.  That was the original logic.  I just transformed the
logic into emu_nid_to_phys[].  If you think you can remove that
safely, please go ahead and submit a patch.  That said, it's not
exactly high priority thing to do.

Thanks.

-- 
tejun