From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <yuanhan.liu@linux.intel.com>
Received: from mga05.intel.com (mga05.intel.com [192.55.52.43])
 by dpdk.org (Postfix) with ESMTP id 459A87EE4
 for <dev@dpdk.org>; Thu, 27 Apr 2017 10:24:25 +0200 (CEST)
Received: from orsmga001.jf.intel.com ([10.7.209.18])
 by fmsmga105.fm.intel.com with ESMTP; 27 Apr 2017 01:24:25 -0700
X-ExtLoop1: 1
X-IronPort-AV: E=Sophos;i="5.37,257,1488873600"; d="scan'208";a="1123994919"
Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.67.162])
 by orsmga001.jf.intel.com with ESMTP; 27 Apr 2017 01:24:23 -0700
Date: Thu, 27 Apr 2017 16:20:47 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: Zhiyong Yang <zhiyong.yang@intel.com>, dev@dpdk.org,
 ciara.loftus@intel.com,
 =?iso-8859-1?Q?Marc-Andr=E9?= Lureau <mlureau@redhat.com>
Message-ID: <20170427082047.GL11512@yliu-dev.sh.intel.com>
References: <1493274893-40764-1-git-send-email-zhiyong.yang@intel.com>
 <57212715-6192-dba2-418a-2418a5d14953@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <57212715-6192-dba2-418a-2418a5d14953@redhat.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Subject: Re: [dpdk-dev] [PATCH] vhost: fix MQ fails to startup
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
X-List-Received-Date: Thu, 27 Apr 2017 08:24:26 -0000

On Thu, Apr 27, 2017 at 09:56:47AM +0200, Maxime Coquelin wrote:
> Hi Zhiyong,
> 
> +Marc-André
> 
> On 04/27/2017 08:34 AM, Zhiyong Yang wrote:
> >vhost since dpdk17.02 + qemu2.7 and above will cause failures of
> >new connection when negotiating to set MQ. (one queue pair works
> >well).Because there exist some bugs in qemu code when introducing
> >VHOST_USER_PROTOCOL_F_REPLY_ACK to qemu. when dealing with the vhost
> >message VHOST_USER_SET_MEM_TABLE for the second time, qemu indeed
> >doesn't send the messge (The message needs to be sent only once)but
> >still will be waiting for dpdk's reply ack, then, qemu is always
> >freezing. DPDK code works in the right way.
> 
> I'm looking at Qemu's vhost_user_set_mem_table() function, but fail to
> see how it could wait for the reply-ack if it didn't send the
> VHOST_USER_SET_MEM_TABLE request before.
> 
> >But the feature
> >VHOST_USER_PROTOCOL_F_REPLY_ACK has to be disabled by default at the
> >dpdk side in order to avoid the feature support of DPDK + qemu at
> >the same time. if doing like that, MQ can works well. Once Qemu bugs
> >have been fixed and upstreamed, we can enable it.
> 
> The problem is for DPDK to detect whether bug is fixed in Qemu.
> Maybe only way would be to have a new protocol feature flag, which is
> not really its role.

Wouldn't that be an overkill, judging that REPLY_ACK is not a must
feature?

	--yliu