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From: "Lu, Wenzhuo" <wenzhuo.lu@intel.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
CC: "dev@dpdk.org" <dev@dpdk.org>
Thread-Topic: [dpdk-dev] [PATCH v3] ethdev: fix DCB config issue on ixgbe
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Date: Thu, 30 Jun 2016 08:23:01 +0000
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Subject: Re: [dpdk-dev] [PATCH v3] ethdev: fix DCB config issue on ixgbe
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Hi Thomas,

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> Sent: Thursday, June 30, 2016 3:42 PM
> To: Lu, Wenzhuo
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3] ethdev: fix DCB config issue on ixgbe
>=20
> 2016-06-30 01:40, Lu, Wenzhuo:
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Lu, Wenzhuo
> > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > > 2016-06-23 01:04, Lu, Wenzhuo:
> > > > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > > > > 2016-05-06 05:33, Wenzhuo Lu:
> > > > > > > +int
> > > > > > > +rte_eth_dev_mq_mode_set(uint8_t port_id,
> > > > > > > +			enum rte_eth_rx_mq_mode rx_mq_mode,
> > > > > > > +			enum rte_eth_tx_mq_mode tx_mq_mode);
> > > > > >
> > > > > > I've really tried to think about it and I think it is more or l=
ess a hack.
> > > > > > First, it is not explained in the doc when we should use
> > > > > > rte_eth_dev_mq_mode_set() instead of a simple call to
> > > > rte_eth_dev_configure().
> > > > > > Second, I don't understand why having a function which
> > > > > > configures the "multiqueue modes" without configuring properly
> RSS/VMDq/DCB.
> > > > > > Last, it is said that rte_eth_dev_configure() "must be invoked
> > > > > > first before any other function in the Ethernet API".
> > After checking the code, Honestly I'm confused. I don't find this descr=
iption.
>=20
> It's in the description of rte_eth_dev_configure():
> 	http://dpdk.org/browse/dpdk/tree/lib/librte_ether/rte_ethdev.h#n1904
The bad news is this rule is not followed. I think the reason is something =
has to be done before configure.

>=20
> > And on the contrary, I find rte_eth_dev_info_get is always called
> > before rte_eth_dev_configure. I believe it's the problem.
> > As rte_eth_dev_configure is not run, rte_eth_dev_info_get cannot get th=
e
> right info.
> > That why I have to add a API to set the mq_mode before
> rte_eth_dev_info_get.
> > Does that mean all the related examples are wrong? Any opinion? Thanks.
>=20
> My opinion is that this area needs a good cleanup and easy API :)
OK. My solution is
1, Remove the description " rte_eth_dev_configure() must be invoked first b=
efore any other function in the Ethernet API ". I think it's reasonable to =
execute the rte_eth_dev_info_get before rte_eth_dev_configure, because we n=
eed to get some NIC specific limitation to check if the configuration is ri=
ght.
2, Add one more argument, " const struct rte_eth_conf *eth_conf ", for rte_=
eth_dev_info_get, like this,
void rte_eth_dev_info_get(uint8_t port_id, struct rte_eth_dev_info *dev_inf=
o, const struct rte_eth_conf *eth_conf);
because getting the right info depends on the configuration.