From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tetsuya Mukawa <mukawa@igel.co.jp>
Subject: Re: [PATCH v4 1/2] vhost: Add callback and private data
 for vhost PMD
Date: Thu, 19 Nov 2015 11:03:50 +0900
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To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
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On 2015/11/17 22:29, Yuanhan Liu wrote:
> On Fri, Nov 13, 2015 at 02:20:30PM +0900, Tetsuya Mukawa wrote:
>> These variables are needed to be able to manage one of virtio devices
>> using both vhost library APIs and vhost PMD.
>> For example, if vhost PMD uses current callback handler and private data
>> provided by vhost library, A DPDK application that links vhost library
>> cannot use some of vhost library APIs.
> Can you be more specific about this?
>
> 	--yliu

How about like below?

commit log:
Currently, when virtio device is created and destroyed, vhost library
will call one of callback handlers.
The vhost PMD need to use this pair of callback handlers to know which
virtio devices are connected actually.
Because we can register only one pair of callbacks to vhost library, if
the PMD use it, DPDK applications
cannot have a way to know the events. This may break legacy DPDK
applications that uses vhost library.
To prevent it, this patch adds one more pair of callbacks to vhost
library especially for the vhost PMD.
With the patch, legacy applications can use the vhost PMD even if they
need additional specific handling
for virtio device creation and destruction.
For example, legacy application can call
rte_vhost_enable_guest_notification() in callbacks to change setting.

Tetsuya