Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752432AbZFRT1u (ORCPT ); Thu, 18 Jun 2009 15:27:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751064AbZFRT1n (ORCPT ); Thu, 18 Jun 2009 15:27:43 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:49414 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750728AbZFRT1n (ORCPT ); Thu, 18 Jun 2009 15:27:43 -0400 To: Jeremy Fitzhardinge Cc: Len Brown , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel Subject: Re: [PATCH RFC] x86/acpi: don't ignore I/O APICs just because there's no local APIC References: <4A329CF8.4050502@goop.org> <4A3A9220.4070807@goop.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: Thu, 18 Jun 2009 12:27:39 -0700 In-Reply-To: <4A3A9220.4070807@goop.org> (Jeremy Fitzhardinge's message of "Thu\, 18 Jun 2009 12\:14\:40 -0700") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: jeremy@goop.org, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, lenb@kernel.org X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: No (on in01.mta.xmission.com); Unknown failure Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1044 Lines: 29 Jeremy Fitzhardinge writes: > On 06/18/09 09:08, Len Brown wrote: >>> In principle, the local APIC and the I/O APIC are distinct (but related) >>> components, which can be independently present. >>> >> >> bzzzzt, but thanks for playing:-) >> > > Perhaps I should have expressed that a bit more clearly: you could, if > mad, build a machine with I/O APICs and some other mechanism for > delivering the interrupts to CPUs. In practice, I doubt anyone ever > has, or ever would. > > The only actual exception I know of is Xen's replacement of the physical > local APIC with a paravirtualized interrupt interface. No one ever has. Xen doesn't have I/O APICs either. Not in any real sense. Xen just has devices that looking like I/O apics if you don't look close. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/