From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161242AbXCHXzI (ORCPT ); Thu, 8 Mar 2007 18:55:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161264AbXCHXzH (ORCPT ); Thu, 8 Mar 2007 18:55:07 -0500 Received: from smtp-outbound-1.vmware.com ([65.113.40.141]:37544 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161242AbXCHXzB (ORCPT ); Thu, 8 Mar 2007 18:55:01 -0500 Message-ID: <45F0A254.4020002@vmware.com> Date: Thu, 08 Mar 2007 15:55:00 -0800 From: Zachary Amsden User-Agent: Thunderbird 1.5.0.10 (X11/20070221) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: Ingo Molnar , tglx@linutronix.de, john stultz , akpm@linux-foundation.org, Linus Torvalds , LKML , Pratap Subrahmanyam , Rusty Russell , Andi Kleen , Daniel Hecht , Daniel Arai , Chris Wright , Virtualization Mailing List Subject: Re: hardwired VMI crap References: <45EF175D.6030609@vmware.com> <1173302503.24738.795.camel@localhost.localdomain> <45EF372E.7030600@goop.org> <1173308717.24738.898.camel@localhost.localdomain> <45EF49E9.7040509@vmware.com> <20070308091019.GA19460@elte.hu> <45EFE010.7080108@vmware.com> <1173352154.24738.1023.camel@localhost.localdomain> <45F0761C.6060107@vmware.com> <45F07D07.5090003@goop.org> <20070308213458.GA24634@elte.hu> <45F09EAE.6090908@goop.org> In-Reply-To: <45F09EAE.6090908@goop.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jeremy Fitzhardinge wrote: > No, but I'm not prejudiced against virtual hardware. If we have a piece > of code that thinks its talking to an apic, then I think its OK to use > that code whether its a real apic or a virtual one, _so long as its > being used in a way that's consistent with its intended interface_. I > have to admit I have not looked at apics - real or virtual - in any > detail, so I won't claim to really understand the details of the > existing arch/i386 code or what VMI's trying to do, but it does seem to > me that it could all be much cleaner. > > And clean is good, we all love clean - and so, agreement! > For APICs, we have two operations - APICRead and APICWrite. It is nice and clean, and plugs in very easily to the APIC accessors available in Linux. Is this not clean? We just don't drive the local timer interrupts through the APIC, we make hypercalls to schedule local timer alarms. Which is something we must do for UP kernels as well, which use the PIT / PIC. So there is a need for having clockevents code which doesn't program timers through the APIC. So we have one separate time device, independent from the traditional hardware timers, and we just program that. This design is not very complex, nor is it unclean, IMHO. Zach