From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [PATCH 1/9] pci-assign: Optionally enable 64bit BARs in guest Date: Tue, 31 Jan 2012 14:08:38 -0700 Message-ID: <1328044118.6937.148.camel@bling.home> References: <20120128142104.25681.93072.stgit@bling.home> <20120128142139.25681.19080.stgit@bling.home> <4F27E15A.1090800@redhat.com> <4F27E25A.1060306@siemens.com> <4F27E3C2.5050204@redhat.com> <4F27E547.3000809@siemens.com> <4F27E83E.7080903@redhat.com> <4F27EAC7.50707@siemens.com> <4F27ED9C.7090604@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Jan Kiszka , "kvm@vger.kernel.org" , "shashidhar.patil@gmail.com" , "Michael S. Tsirkin" To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:7272 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753107Ab2AaVIm (ORCPT ); Tue, 31 Jan 2012 16:08:42 -0500 In-Reply-To: <4F27ED9C.7090604@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, 2012-01-31 at 15:33 +0200, Avi Kivity wrote: > On 01/31/2012 03:21 PM, Jan Kiszka wrote: > > On 2012-01-31 14:10, Avi Kivity wrote: > > > On 01/31/2012 02:57 PM, Jan Kiszka wrote: > > >>>>> Seems fine, but do we really need the option? If it doesn't work we > > >>>>> should treat it as an ordinary but and fix it. > > >>>> > > >>>> So far it's against the architecture of the emulated system: our current > > >>>> chipset predates 64 bit PCI. > > >>>> > > >>> > > >>> Then it should be enabled/disabled at the chipset level. > > >> > > >> Makes me wonder if we already do some filtering if the device supports > > >> 64 bit but the next bridge does not. > > >> > > > > > > Our 440fx does support 64-bit bars, so the question doesn't arise for > > > x86. Instead we violate the spec. > > > > If you mean by "our" the 440fx-qemu, not the real 440fx. That one does > > not even support >1GB RAM. > > Yes, that's what I meant. It also supports pci hotplug, more slots, cpu > hotplug, etc. I'll drop this patch for now, it was just something I enabled based on a query from MST and didn't want to lose it. Maybe we need the option in PCI core, but I'm just turn it on and hope for the best w/o giving users a way to disable it. Thanks, Alex