Date: Mon, 14 Jul 2008 21:15:12 -0600
From: Matthew Wilcox <matthew@wil.cx>
To: Alex Chiang <achiang@hp.com>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
       linux-acpi@vger.kernel.org
Subject: Re: [PATCH 01/14] Introduce cpu_enabled_map and friends
Message-ID: <20080715031512.GF14894@parisc-linux.org>
References: <20080715023344.2528.1836.stgit@blender.achiang> <20080715023349.2528.9423.stgit@blender.achiang>
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On Mon, Jul 14, 2008 at 08:33:49PM -0600, Alex Chiang wrote:
> Currently, the following cpu maps exist:
> 
> 	cpu_possible_map - map of populatable CPUs
> 	cpu_present_map  - map of populated CPUs
> 	cpu_online_map   - map of schedulable CPUs
> 
> These maps do not provide the concept of populated, but disabled CPUs.
> 
> That is, a system may contain CPU modules that are physically plugged
> in, but disabled by system firmware.

I don't understand why we want to know about these CPUs.  Surely they
should be 'possible', but not 'present'?  What useful thing can Linux do
with them?

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
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