Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932288AbVKWW0Z (ORCPT ); Wed, 23 Nov 2005 17:26:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932588AbVKWW0Y (ORCPT ); Wed, 23 Nov 2005 17:26:24 -0500 Received: from terminus.zytor.com ([192.83.249.54]:57299 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S932288AbVKWW0X (ORCPT ); Wed, 23 Nov 2005 17:26:23 -0500 Message-ID: <4384EC68.1060302@zytor.com> Date: Wed, 23 Nov 2005 14:25:44 -0800 From: "H. Peter Anvin" User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Andi Kleen CC: Linus Torvalds , Alan Cox , Gerd Knorr , Dave Jones , Zachary Amsden , Pavel Machek , Andrew Morton , Linux Kernel Mailing List , Zwane Mwaikambo , Pratap Subrahmanyam , Christopher Li , "Eric W. Biederman" , Ingo Molnar Subject: Re: [patch] SMP alternatives References: <1132764133.7268.51.camel@localhost.localdomain> <20051123163906.GF20775@brahms.suse.de> <1132766489.7268.71.camel@localhost.localdomain> <4384AECC.1030403@zytor.com> <1132782245.13095.4.camel@localhost.localdomain> <20051123214344.GU20775@brahms.suse.de> <20051123222212.GV20775@brahms.suse.de> In-Reply-To: <20051123222212.GV20775@brahms.suse.de> 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 Content-Length: 1170 Lines: 33 Andi Kleen wrote: > On Wed, Nov 23, 2005 at 02:15:24PM -0800, Linus Torvalds wrote: > >> >>On Wed, 23 Nov 2005, Andi Kleen wrote: >> >>>>THAT is what I'd like to have CPU support for. Not for UP (it's going >>>>away), and not for the kernel (it's never single-threaded). >>> >>>There is one reasonly interesting special case that will probably stay >>>around: single CPU guest in a virtualized environment. >> >>.. and then the _virtualizer_ should just set the bit. > > That wouldn't work if it's limited limited to ring 3. > > Also currently at least the Xen the driver interfaces seem to > rely on lock, but perhaps that can be changed. > Well, with VTX or Pacifica virtualization is in ring 3. The fact that Xen isn't is a workaround for current hardware, so when we're talking about new hardware it's pointless. What you really want is one bit for kernel mode (cpl 0-2) and one for user mode (cpl 3). -hpa - 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/