From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39205) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a4PyQ-0005Wj-MF for qemu-devel@nongnu.org; Thu, 03 Dec 2015 04:14:50 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a4PyM-00006R-IT for qemu-devel@nongnu.org; Thu, 03 Dec 2015 04:14:46 -0500 Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:56129) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a4PyM-00006G-7T for qemu-devel@nongnu.org; Thu, 03 Dec 2015 04:14:42 -0500 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 3 Dec 2015 09:14:39 -0000 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 65C7D219004D for ; Thu, 3 Dec 2015 09:14:30 +0000 (GMT) Received: from d06av01.portsmouth.uk.ibm.com (d06av01.portsmouth.uk.ibm.com [9.149.37.212]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id tB39EatZ328162 for ; Thu, 3 Dec 2015 09:14:37 GMT Received: from d06av01.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av01.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id tB39Eaph013577 for ; Thu, 3 Dec 2015 02:14:36 -0700 References: <1449065398-45267-1-git-send-email-cornelia.huck@de.ibm.com> <20151202184036-mutt-send-email-mst@redhat.com> From: Christian Borntraeger Message-ID: <566007FB.6000304@de.ibm.com> Date: Thu, 3 Dec 2015 10:14:35 +0100 MIME-Version: 1.0 In-Reply-To: <20151202184036-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for-2.5] virtio: handle non-virtio-1-capable backend List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" , Cornelia Huck Cc: jasowang@redhat.com, qemu-devel@nongnu.org On 12/02/2015 05:43 PM, Michael S. Tsirkin wrote: > On Wed, Dec 02, 2015 at 03:09:58PM +0100, Cornelia Huck wrote: >> If you run a qemu advertising VERSION_1 with an old kernel where >> vhost did not yet support VERSION_1, you'll end up with a device >> that is {modern pci|ccw revision 1} but does not advertise VERSION_1. >> This is not a sensible configuration and is rejected by the Linux >> guest drivers. >> >> To fix this, add a ->post_plugged() callback invoked after features >> have been queried that can handle the VERSION_1 bit being withdrawn >> and change pci (only setup modern if VERSION_1 is still present) and >> ccw (fall back to revision 0 if VERSION_1 is gone). >> >> Signed-off-by: Cornelia Huck > > > Unfortunately this is too late: we need to know > whether modern will be supported to know whether > to add the pci express capability :( I can at least confirm that this patch "fixes" the guest error message virtio_net virtio0: virtio: device uses modern interface but does not have VIRTIO_F_VERSION_1 virtio_net: probe of virtio0 failed with error -22 is gone. but yes, its not enough for the other aspects. > > Maybe this should be moved into plugged > callback?