From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48538) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c99ve-0003F0-Au for qemu-devel@nongnu.org; Tue, 22 Nov 2016 07:12:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c99vY-0005Xc-HB for qemu-devel@nongnu.org; Tue, 22 Nov 2016 07:12:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36174) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c99vY-0005WU-AG for qemu-devel@nongnu.org; Tue, 22 Nov 2016 07:11:56 -0500 References: <1479419887-10515-1-git-send-email-maxime.coquelin@redhat.com> <1479419887-10515-4-git-send-email-maxime.coquelin@redhat.com> <20161118003558-mutt-send-email-mst@kernel.org> <3120fbd4-99eb-a9f2-a2b3-a5f686dbc7ee@redhat.com> <20161121184537-mutt-send-email-mst@kernel.org> From: Maxime Coquelin Message-ID: <9e43d106-b2b8-2e89-2f2e-600e0ca48900@redhat.com> Date: Tue, 22 Nov 2016 13:11:50 +0100 MIME-Version: 1.0 In-Reply-To: <20161121184537-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC v2 3/3] virtio-net: Add MTU feature support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: aconole@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org, jasowang@redhat.com, yuanhan.liu@linux.intel.com On 11/21/2016 05:48 PM, Michael S. Tsirkin wrote: >>>> > > > @@ -1695,6 +1706,7 @@ static void virtio_net_set_config_size(VirtIONet *n, uint64_t host_features) >>>> > > > { >>>> > > > int i, config_size = 0; >>>> > > > virtio_add_feature(&host_features, VIRTIO_NET_F_MAC); >>>> > > > + virtio_add_feature(&host_features, VIRTIO_NET_F_MTU); >>>> > > > for (i = 0; feature_sizes[i].flags != 0; i++) { >>>> > > > if (host_features & feature_sizes[i].flags) { >>>> > > > config_size = MAX(feature_sizes[i].end, config_size); >>>> > > > @@ -1922,6 +1934,8 @@ static Property virtio_net_properties[] = { >>>> > > > DEFINE_PROP_STRING("tx", VirtIONet, net_conf.tx), >>>> > > > DEFINE_PROP_UINT16("rx_queue_size", VirtIONet, net_conf.rx_queue_size, >>>> > > > VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE), >>>> > > > + DEFINE_PROP_BIT("host_mtu", VirtIONet, host_features, >>>> > > > + VIRTIO_NET_F_MTU, true), >>>> > > > DEFINE_PROP_END_OF_LIST(), >>>> > > > }; >>>> > > > >>> > > >>> > > Cross version migration support is missing here. >> > Sorry, I'm not sure to understand what you expect here. >> > Could you please provide more details? > feature bits must be consistent for a given machine type. > So you can't add them unconditionally for old machine > types, they must look the same as they looked when > we put that machine type out. Ok, thanks for clarifying. IIUC, idea is to let it enabled by default, and add entries in HW_COMPAT_2_x macros to disable it in all previous versions? Thanks, Maxime