From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id 96A169E7 for ; Thu, 13 Oct 2016 09:53:25 +0200 (CEST) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga102.fm.intel.com with ESMTP; 13 Oct 2016 00:53:25 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,339,1473145200"; d="scan'208";a="1064194970" Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.67.162]) by orsmga002.jf.intel.com with ESMTP; 13 Oct 2016 00:53:22 -0700 Date: Thu, 13 Oct 2016 15:54:15 +0800 From: Yuanhan Liu To: Olivier MATZ Cc: dev@dpdk.org, konstantin.ananyev@intel.com, sugesh.chandran@intel.com, bruce.richardson@intel.com, jianfeng.tan@intel.com, helin.zhang@intel.com, adrien.mazarguil@6wind.com, stephen@networkplumber.org, dprovan@bivio.net, xiao.w.wang@intel.com Message-ID: <20161013075415.GS16751@yliu-dev.sh.intel.com> References: <1475485223-30566-1-git-send-email-olivier.matz@6wind.com> <1475485223-30566-4-git-send-email-olivier.matz@6wind.com> <20161012144108.GN16751@yliu-dev.sh.intel.com> <57FE5E55.4010809@6wind.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57FE5E55.4010809@6wind.com> User-Agent: Mutt/1.5.23 (2014-03-12) Subject: Re: [dpdk-dev] [PATCH v2 03/12] virtio: reinitialize the device in configure callback X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 13 Oct 2016 07:53:26 -0000 On Wed, Oct 12, 2016 at 06:01:25PM +0200, Olivier MATZ wrote: > Hello Yuanhan, > > On 10/12/2016 04:41 PM, Yuanhan Liu wrote: > >On Mon, Oct 03, 2016 at 11:00:14AM +0200, Olivier Matz wrote: > >>@@ -1344,6 +1347,7 @@ virtio_dev_configure(struct rte_eth_dev *dev) > >> { > >> const struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode; > >> struct virtio_hw *hw = dev->data->dev_private; > >>+ uint64_t req_features; > >> int ret; > >> > >> PMD_INIT_LOG(DEBUG, "configure"); > >>@@ -1353,6 +1357,14 @@ virtio_dev_configure(struct rte_eth_dev *dev) > >> return -EINVAL; > >> } > >> > >>+ req_features = VIRTIO_PMD_GUEST_FEATURES; > >>+ /* if request features changed, reinit the device */ > >>+ if (req_features != hw->req_guest_features) { > >>+ ret = virtio_init_device(dev, req_features); > >>+ if (ret < 0) > >>+ return ret; > >>+ } > > > >Why do you have to reset virtio here? This doesn't make too much sense > >to me. > > > >IIUC, you want to make sure those TSO related features being unset at > >init time, and enable it (by doing reset) when it's asked to be enabled > >(by rte_eth_dev_configure)? > > > >Why not always setting those features? We could do the actual offloads > >when: > > > >- those features have been negoiated > > > >- they are enabled through rte_eth_dev_configure > > > >With that, I think we could avoid the reset here? > > It would work for TX, since you decide to use or not the feature. But I > think this won't work for RX: if you negociate LRO at init, the host may > send you large packets, even if LRO is disabled in dev_configure. I see. Thanks. Besides, I think you should return error when LRO is not negoiated after the reset (say, when it's disabled through qemu command line)? --yliu