From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f175.google.com (mail-wj0-f175.google.com [209.85.210.175]) by dpdk.org (Postfix) with ESMTP id 713632C8 for ; Mon, 28 Nov 2016 23:18:55 +0100 (CET) Received: by mail-wj0-f175.google.com with SMTP id xy5so129028752wjc.0 for ; Mon, 28 Nov 2016 14:18:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:user-agent:in-reply-to :references:mime-version:content-transfer-encoding; bh=WFMFqhPELU0EuPg6E8GIfvdaQdViPTDbK7bdhAlIv0Y=; b=EVuf1cgW0nDh+oTgV0FtA+Rbs2eycjhGLCYR0vciF39htfwPbrkKryTGusFgj3EVbe 4nJqIespQYgUsaLeDqLoP3wWksLdRCAuh5dobTM1nBpxt4IY9rhHVspmfnzCA4xa907z UvNKkrTr1q3CjWeaDyui02wHIopsbzQ4RQEke1wI0LIwCiRMSBxY92AxK4V+Sl9XrdDI wHYlo1lbJwdm+VqsdCftBXVnz0dEwL5xPI1If8Ja9nYmDYqr78/H/ufETbMWdNl5fiO8 DZK1oWLOou3zCUskkTB0nw5a7KOoq/mQknRDLFTzk/VjJY9Rp1u35iwkR+4sGVhn8PgV dP0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:user-agent :in-reply-to:references:mime-version:content-transfer-encoding; bh=WFMFqhPELU0EuPg6E8GIfvdaQdViPTDbK7bdhAlIv0Y=; b=PBb/xDuW03uTHyoMPgPfznvx7uEBZaOXoPuS4nEWHbdP600txdGvvCHeI4Ti6gD/vk zYZ/7iDeNa0vJh+FKmBkJV2SsNz4TZQAhK+416KuNRiIdKjzbXt7BZF8Dkm7tBGe2D7w ylf5T8O/Iddvj2eccWk32eThPk0kNPLVpyDN+Mk4+IUipRn2J9WlzO0QqjqUpd+H+jri dJI+UILpKi2KaYq/v0caGCp49VK5rbrLgxBOoEMjv59ua0aJKas9Fknd5+KMwIFBNAtR oVm/VSPnGu6twD0zpriEEujm43kswVrypDApyKgA3u/rCNXXyzoQW/WYHVmc3qiQjSm+ +gMg== X-Gm-Message-State: AKaTC021BzNq8qTtxSKTqUJ85hls+HyznkCBDk5sxISuP39RrvaDqvs0yiY7y207RFllnqbR X-Received: by 10.194.109.65 with SMTP id hq1mr20422216wjb.37.1480371534902; Mon, 28 Nov 2016 14:18:54 -0800 (PST) Received: from xps13.localnet (184.203.134.77.rev.sfr.net. [77.134.203.184]) by smtp.gmail.com with ESMTPSA id d8sm30994400wmi.21.2016.11.28.14.18.53 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Nov 2016 14:18:54 -0800 (PST) From: Thomas Monjalon To: Maxime Coquelin , "Kavanagh, Mark B" , Kevin Traynor , Yuanhan Liu Cc: dev@dpdk.org, "Weglicki, MichalX" , "Michael S. Tsirkin" , Stephen Hemminger , qemu-devel@nongnu.org, libvir-list@redhat.com, vpp-dev@lists.fd.io, =?ISO-8859-1?Q?Marc=2DAndr=E9?= Lureau , olivier.matz@6wind.com Date: Mon, 28 Nov 2016 23:18:53 +0100 Message-ID: <5176838.Upmb1ZYUhB@xps13> User-Agent: KMail/4.14.10 (Linux/4.5.4-1-ARCH; KDE/4.14.11; x86_64; ; ) In-Reply-To: <67cfb109-8729-916e-5535-80af620bafe5@redhat.com> References: <20161011173526-mutt-send-email-mst@kernel.org> <67cfb109-8729-916e-5535-80af620bafe5@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [dpdk-dev] dpdk/vpp and cross-version migration for vhost 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: Mon, 28 Nov 2016 22:18:55 -0000 2016-11-28 16:28, Maxime Coquelin: > On 11/24/2016 04:24 PM, Kavanagh, Mark B wrote: > > DPDK v16.04 added support for vHost User TSO; as such, by default, > > TSO is advertised to guest devices as an available feature during > > feature negotiation with QEMU. > > However, while the vHost user backend sets up the majority of the > > mbuf fields that are required for TSO, there is still a reliance > > on the associated DPDK application (i.e. in this case OvS-DPDK) > > to set the remaining flags and/or offsets. > > Since OvS-DPDK doesn't currently provide that functionality, it is > > necessary to explicitly disable TSO; otherwise, undefined behaviour > > will ensue. > > Thanks Mark for the clarification. > > In this case, maybe we could add a DPDK build option to disable Vhost's > TSO support, that would be selected for OVS packages? Why do you prefer a build-time option rather than the run-time config with rte_vhost_feature_disable()? Because we need to lock the features? Reminder: build-time configuration options are forbidden in DPDK for such usage. It would prevent other applications from using the feature in a given distribution, just because it is not implemented in OVS. > Does that sound reasonable? Maybe I'm missing something but I feel it is more reasonnable to implement the missing code in OVS. If something is missing in DPDK, do not hesitate to request or add more helper functions.