From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43635) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wzk0d-0005hY-F5 for qemu-devel@nongnu.org; Wed, 25 Jun 2014 06:01:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wzk0V-0008W6-Vf for qemu-devel@nongnu.org; Wed, 25 Jun 2014 06:00:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:21384) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wzk0V-0008W2-OH for qemu-devel@nongnu.org; Wed, 25 Jun 2014 06:00:47 -0400 Date: Wed, 25 Jun 2014 13:00:50 +0300 From: "Michael S. Tsirkin" Message-ID: <20140625100050.GF6357@redhat.com> References: <53AA7DCE.2030100@redhat.com> <20140625083121.GC32652@redhat.com> <53AA8ACF.3070101@redhat.com> <20140625084835.GF32652@redhat.com> <53AA8E7D.809@intel.com> <20140625090925.GH32652@redhat.com> <53AA9480.1010005@intel.com> <53AA96DF.6070501@redhat.com> <53AA9B58.6050803@intel.com> <53AA9C4E.9070506@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53AA9C4E.9070506@redhat.com> Subject: Re: [Qemu-devel] [v5][PATCH 0/5] xen: add Intel IGD passthrough support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: peter.maydell@linaro.org, xen-devel@lists.xensource.com, stefano.stabellini@eu.citrix.com, allen.m.kay@intel.com, Kelly.Zytaruk@amd.com, qemu-devel@nongnu.org, anthony.perard@citrix.com, anthony@codemonkey.ws, yang.z.zhang@intel.com, "Chen, Tiejun" On Wed, Jun 25, 2014 at 11:54:22AM +0200, Paolo Bonzini wrote: > Il 25/06/2014 11:50, Chen, Tiejun ha scritto: > >> > >>For past devices, we know which BARs they use. For future devices, it > >>would be nice if the PCH/MCH backdoor was specified so that we know they > >>will leave a free BAR for virtualization. > >> > > > >Now I'm a bit confused about BAR here. > > > >You're saying we will reserve a free BAR to address those information to > >expose to guest, but which device does this free BAR belong to? The > >video device? Or PCH/MCH? > > The video device. If the host device does not have the BAR (which will be > the common case), QEMU can emulate it like this: > > - offsets 0x0000..0x0fff map to configuration space of the host MCH > > - offsets 0x1000..0x1fff map to configuration space of the host PCH > > Of course this is only limited to offsets that are needed by the driver. > > Paolo Ow. If you need hacks like this, describe this in ACPI. But I really hope not. -- MST