From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 730D79E7 for ; Mon, 9 Nov 2015 20:55:51 +0100 (CET) Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 6E04314AA2; Mon, 9 Nov 2015 19:55:50 +0000 (UTC) Received: from redhat.com (ovpn-116-62.ams2.redhat.com [10.36.116.62]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id tA9Jtlht028356; Mon, 9 Nov 2015 14:55:48 -0500 Date: Mon, 9 Nov 2015 21:55:47 +0200 From: "Michael S. Tsirkin" To: Thomas Monjalon Message-ID: <20151109215105-mutt-send-email-mst@redhat.com> References: <1444907319-26348-1-git-send-email-marcel@redhat.com> <20151016135230.GF9980@bricha3-MOBL3> <20151018095438-mutt-send-email-mst@redhat.com> <2413695.XHLO16SCPC@xps13> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2413695.XHLO16SCPC@xps13> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 Cc: Marcel Apfelbaum , dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH] vhost-user: enable virtio 1.0 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, 09 Nov 2015 19:55:51 -0000 On Fri, Oct 30, 2015 at 06:48:09PM +0100, Thomas Monjalon wrote: > 2015-10-18 10:04, Michael S. Tsirkin: > > On Fri, Oct 16, 2015 at 02:52:30PM +0100, Bruce Richardson wrote: > > > On Thu, Oct 15, 2015 at 04:18:59PM +0300, Michael S. Tsirkin wrote: > > > > On Thu, Oct 15, 2015 at 02:08:39PM +0300, Marcel Apfelbaum wrote: > > > > > Make vhost-user virtio 1.0 compatible by adding it to the > > > > > supported features and keeping the header length > > > > > the same as for mergeable RX buffers. > > > > > > > > > > Signed-off-by: Marcel Apfelbaum > > > > > > > > Looks good to me > > > > > > > > Acked-by: Michael S. Tsirkin > > > > > > > > Just one question: dpdk is only supported on little-endian > > > > platforms at the moment, right? > > > > > > A recent release added in support for PPC (patches supplied by IBM). For > > > example, see: > > > http://dpdk.org/browse/dpdk/commit/?id=704ba3770032c5a901719d3837845581d5a56b58 > > > > > > /Bruce > > > > This will require more work then as 1.0 is a different > > endian-ness from 0.9. It's up to you guys to decide > > whether correct BE support is now a requirement for all > > new dpdk code. Let us know. > > I'm not sure to understand. > Yes DPDK must work on big endian platforms. > Does this patch prevent from using virtio 0.9 with big endian? No it doesn't. virtio 0.9 with big endian most likely does not work reliably with vhost-user at the moment since qemu does not tell vhost-user about guest endian-ness (though it's common to have it match host, then it will work by luck). > Does it work with old QEMU not supporting virtio 1.0? Yes it does. virtio 1 requires a bunch of fields to be little endian. If someone uses this patch with new QEMU on BE machine, things won't work: you need if (virtio_1) cpu_to_le On LE, cpu_to_le is a NOP so things work by luck. In other words this patch is fine, more is needed to make virtio 1 work on BE hosts. -- MST