From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 1/9] pci-assign: Optionally enable 64bit BARs in guest Date: Tue, 31 Jan 2012 23:14:16 +0200 Message-ID: <20120131211416.GA6843@redhat.com> 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> <1328044118.6937.148.camel@bling.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Jan Kiszka , "kvm@vger.kernel.org" , "shashidhar.patil@gmail.com" To: Alex Williamson Return-path: Received: from mx1.redhat.com ([209.132.183.28]:38483 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753483Ab2AaVOS (ORCPT ); Tue, 31 Jan 2012 16:14:18 -0500 Content-Disposition: inline In-Reply-To: <1328044118.6937.148.camel@bling.home> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Jan 31, 2012 at 02:08:38PM -0700, Alex Williamson wrote: > 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 The patch itself makes sense to me. Avi found some bugs in 64 bit BAR handling, let's wait till that is fixed then merge this patch.