Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751191AbWIKH4T (ORCPT ); Mon, 11 Sep 2006 03:56:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751197AbWIKH4T (ORCPT ); Mon, 11 Sep 2006 03:56:19 -0400 Received: from gw.goop.org ([64.81.55.164]:29848 "EHLO mail.goop.org") by vger.kernel.org with ESMTP id S1751191AbWIKH4T (ORCPT ); Mon, 11 Sep 2006 03:56:19 -0400 Message-ID: <4505169C.3010507@goop.org> Date: Mon, 11 Sep 2006 00:56:12 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 1.5.0.5 (X11/20060907) MIME-Version: 1.0 To: Ingo Molnar CC: Andrew Morton , Andi Kleen , Laurent Riffard , Arjan van de Ven , Kernel development list , Jeremy Fitzhardinge Subject: Re: 2.6.18-rc6-mm1: GPF loop on early boot References: <200609101032.17429.ak@suse.de> <20060910115722.GA15356@elte.hu> <200609101334.34867.ak@suse.de> <20060910132614.GA29423@elte.hu> <20060910093307.a011b16f.akpm@osdl.org> <450499D3.5010903@goop.org> <20060911051028.GA10084@elte.hu> <450510E0.8080906@goop.org> <20060911072959.GA2322@elte.hu> <45051330.5050205@goop.org> <20060911073809.GB3188@elte.hu> In-Reply-To: <20060911073809.GB3188@elte.hu> 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: 1139 Lines: 32 Ingo Molnar wrote: > btw., what's the connection of %gs based PDA to Xen and > paravirtualization in general - %esp based current is just as > Xen-friendly, or am i wrong? I guess there must be some connection, > given that you are working on this ;) > Yep. The goal is to put the Xen VCPU structure into the PDA, so that it can be easily accessed. At present, masking events (ie, cli), is something along the lines of xen_shared_info->vcpu[smp_processor_id()].mask = 1 which comes out to something like 20 bytes of code, and is probably too awkward to inline. If the vcpu is in the PDA, it would come out to: movb $1, %gs:xen_vcpu_mask which has the added benefit of not needing a register. Even without modifying Xen to allow us to place the VCPU structure, putting a VCPU pointer into the PDA helps a lot: mov %gs:xen_vcpu, %eax movb $1, mask(%eax) J - 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/