From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59820) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTCF9-0001Kx-0D for qemu-devel@nongnu.org; Tue, 09 Feb 2016 12:38:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aTCF4-0007aN-UH for qemu-devel@nongnu.org; Tue, 09 Feb 2016 12:38:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51841) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTCF4-0007Zr-Pd for qemu-devel@nongnu.org; Tue, 09 Feb 2016 12:38:22 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id D6C25804FE for ; Tue, 9 Feb 2016 17:38:21 +0000 (UTC) From: Laurent Vivier Message-ID: <56BA240A.6060409@redhat.com> Date: Tue, 9 Feb 2016 18:38:18 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] "x-disable-pcie" virtio-pci property in compat_props (HW_COMPAT_2_4) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel qemu-devel Cc: Marcel Apfelbaum , Eduardo Habkost Hi, I'm playing with a qemu-2.5.0 and pc-i440fx-2.4 machine type, and perhaps I don't understand correctly the compat_props machinery but there is something strange for me: in qemu-2.5.0, hw/virtio/virtio-pci.c: 1880 DEFINE_PROP_BIT("x-disable-pcie", VirtIOPCIProxy, flags, 1881 VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT, false), So I guess a new default machine (pc-i440fx-2.5) will be defined by default with "x-disable-pcie" set to "false". and in qemu-2.5, include/hw/compat.h: 3 4 #define HW_COMPAT_2_4 \ 5 {\ .. 14 .driver = "virtio-pci",\ 15 .property = "x-disable-pcie",\ 16 .value = "on",\ 17 },{\ So I guess a new machine pc-i440fx-2.4 created with qemu-2.5.0 will have "x-disable-pcie" set to true (as with qemu-2.4.0 this feature is not available). But in this case "x-disable-pcie" is always set to "false". So the questions are: - do I understand correctly? - I check "x-disable-pcie" for "virtio-*-pci" devices (virtio-net-pci, virtio-balloon-pci, ..."), should they inherit the behavior from their parent "virtio-pci"? (they should, as virtio-pci is an abstract device type) My test: - take qemu-2.5.0 (a8c40fa Update version for v2.5.0 release) - start it with "-M pc-i440fx-2.5 -device virtio-balloon-pci -S", "info qtree": bus: pci.0 type PCI dev: virtio-balloon-pci, id "" ... x-disable-pcie = false - start it with "-M pc-i440fx-2.4 -device virtio-balloon-pci -S", "info qtree": bus: pci.0 type PCI dev: virtio-balloon-pci, id "" ... x-disable-pcie = false Any explanation is very welcome. Thanks, Laurent