From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60878) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a4B47-0003AH-Id for qemu-devel@nongnu.org; Wed, 02 Dec 2015 12:19:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a4B43-0001oL-Hm for qemu-devel@nongnu.org; Wed, 02 Dec 2015 12:19:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59069) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a4B43-0001oC-C7 for qemu-devel@nongnu.org; Wed, 02 Dec 2015 12:19:35 -0500 Date: Wed, 2 Dec 2015 19:19:32 +0200 From: "Michael S. Tsirkin" Message-ID: <20151202191841-mutt-send-email-mst@redhat.com> References: <1449066801-3002-1-git-send-email-shmulik.ladkani@ravellosystems.com> <565F0A20.8050507@redhat.com> <20151202184610-mutt-send-email-mst@redhat.com> <20151202191247.7326c7a3@halley> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151202191247.7326c7a3@halley> Subject: Re: [Qemu-devel] [PATCH v2 for-2.5] virtio-pci: Set the QEMU_PCI_CAP_EXPRESS capability early in its DeviceClass realize method List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Shmulik Ladkani Cc: Marcel Apfelbaum , qemu-devel@nongnu.org On Wed, Dec 02, 2015 at 07:12:47PM +0200, Shmulik Ladkani wrote: > Hi Michael, > > On Wed, 2 Dec 2015 18:49:24 +0200 "Michael S. Tsirkin" wrote: > > On Wed, Dec 02, 2015 at 05:11:28PM +0200, Marcel Apfelbaum wrote: > > > The only thing I want to mention here, (see earlier discussion: https://www.mail-archive.com/qemu-devel@nongnu.org/msg338963.html) > > > is that in some cases the PCI config space will have PCIe length, even if the device is not express. > > > > > > To be more precise, the only interesting scenario is when we plug a virtio device directly into > > > the root complex, in this case we'll have a PCI device with a PCIe config space. > > > > > > However this happens for other devices as well, it looks like a common practice. > > > > Problem is, if this happens migration breaks as we > > changed config space size from 2.4. > > Correct me if wrong, but as long as a pre 2.5 hardware is used, Marcel's > x-disable-pcie gets on (see HW_COMPAT_2_4), thus the device will not be > a "pci_is_express", and it will have a small config space size. Isn't it > so? > > Regards, > Shmulik OK. Still, I do not want to migrate 4k of config space for pci devices. -- MST