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Date: Mon, 23 May 2016 21:24:26 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: Thomas Monjalon <thomas.monjalon@6wind.com>,
 Ferruh Yigit <ferruh.yigit@intel.com>, dev@dpdk.org,
 Tetsuya Mukawa <mukawa@igel.co.jp>
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Subject: Re: [dpdk-dev] [PATCH v2] vhost: add support for dynamic vhost PMD
 creation
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On Fri, May 20, 2016 at 11:37:47AM +0100, Bruce Richardson wrote:
> On Thu, May 19, 2016 at 06:44:44PM +0200, Thomas Monjalon wrote:
> > 2016-05-19 17:28, Ferruh Yigit:
> > > On 5/19/2016 9:33 AM, Thomas Monjalon wrote:
> > > > 2016-05-18 18:10, Ferruh Yigit:
> > > >> Add rte_eth_from_vhost() API to create vhost PMD dynamically from
> > > >> applications.
> > > > 
> > > > How is it different from rte_eth_dev_attach() calling rte_eal_vdev_init()?
> > > > 
> > > 
> > > When used rte_eth_dev_attach(), application also needs to do:
> > > rte_eth_dev_configure()
> > > rte_eth_rx_queue_setup()
> > > rte_eth_tx_queue_setup()
> > > rte_eth_dev_start()
> > > 
> > > rte_eth_from_vhost() does these internally, easier to use for applications.
> > 
> > This argument is not sufficient.
> > We are not going to add new APIs just for wrapping others.
> 
> Why not - if there is a sufficient increase in developer usability by doing so?
> Having one API that saves an app from having to call 5 other APIs looks like
> something that should always be given fair consideration.

Good point. Judging that vhost is not the only virtual device we
support, and it may also look reasonable to add something similar
for others in future (say, IIRC, you proposed two more internally
that also introduced similar APIs). So, instead of introducing a
new API for each such vdev, may we introduce a common one? Say,
a refined rte_eth_dev_attach(), including dev_configure(),
queue_setup(), etc.

Makes sense?

	--yliu