From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 01/14] Introduce cpu_enabled_map and friends Date: Tue, 15 Jul 2008 12:03:27 +0200 Message-ID: <87wsjnxy4w.fsf@basil.nowhere.org> References: <20080715023344.2528.1836.stgit@blender.achiang> <20080715023349.2528.9423.stgit@blender.achiang> <20080715031512.GF14894@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from smtp-out01.alice-dsl.net ([88.44.60.11]:27346 "EHLO smtp-out01.alice-dsl.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752645AbYGOKD6 (ORCPT ); Tue, 15 Jul 2008 06:03:58 -0400 In-Reply-To: <20080715031512.GF14894@parisc-linux.org> (Matthew Wilcox's message of "Mon, 14 Jul 2008 21:15:12 -0600") Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Wilcox Cc: Alex Chiang , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-acpi@vger.kernel.org Matthew Wilcox writes: > > 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? He explained it in the intro, near the end (I nearly complained about this too when I hadn't finished reading it completely :): |The big picture implication is that we can allow userspace |to interact with disabled CPUs. In this particular example, |we provide a knob that lets a sysadmin schedule any present |CPU for firmware deconfiguration or enablement. The reason sounds pretty exotic, but ok. -Andi