Re: [dpdk-dev] Question on examples/multi_process app

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> >
> >> -----Original Message-----
> >> From: Richardson, Bruce
> >> Sent: Wednesday, March 23, 2016 11:45 AM
> >> To: Ananyev, Konstantin
> >> Cc: Harish Patil; dev@dpdk.org
> >> Subject: Re: [dpdk-dev] Question on examples/multi_process app
> >>
> >> On Wed, Mar 23, 2016 at 11:09:17AM +0000, Ananyev, Konstantin wrote:
> >> > Hi everyone,
> >> >
> >> > > -----Original Message-----
> >> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce
> >>Richardson
> >> > > Sent: Tuesday, March 22, 2016 9:38 PM
> >> > > To: Harish Patil
> >> > > Cc: dev@dpdk.org
> >> > > Subject: Re: [dpdk-dev] Question on examples/multi_process app
> >> > >
> >> > > On Tue, Mar 22, 2016 at 08:03:42PM +0000, Harish Patil wrote:
> >> > > > Hi,
> >> > > > I have a question regarding symmetric_mp and mp_server
> >>applications under
> >> > > > examples/multi_process. In those apps,
> >>rte_eth_promiscuous_enable() is
> >> > > > called before rte_eth_dev_start(). Is this the correct way to
> >>initialize
> >> > > > the port/device? As per the description in
> >> > > > http://dpdk.org/doc/api/rte__ethdev_8h.html:
> >> > > >
> >> > > > "The functions exported by the application Ethernet API to setup
> >>a device
> >> > > > designated by its port identifier must be invoked in the
> >>following order:
> >> > > >
> >> > > > * rte_eth_dev_configure()
> >> > > > * rte_eth_tx_queue_setup()
> >> > > > * rte_eth_rx_queue_setup()
> >> > > > * rte_eth_dev_start()
> >> > > >
> >> > > > Then, the network application can invoke, in any order, the
> >>functions
> >> > > > exported by the Ethernet API to get the MAC address of a given
> >>device, to
> >> > > > get the speed and the status of a device physical link, to
> >> > > > receive/transmit [burst of] packets, and so on.”
> >> > > >
> >> > > > So should I consider this as an application issue or whether the
> >>PMD is
> >> > > > expected to handle it? If PMD is to handle it, then should the
> >>PMD be:
> >> > > >
> >> > > > 1) Rejecting the Promisc config? OR
> >> > > > 2) Cache the config and apply when dev_start() is called at later
> >>point?
> >> >
> >> > Yes as I remember 2) is done.
> >> > dev_start() invokes rte_eth_dev_config_restore(), which restores
> >> > promisc mode, mac addresses, etc.
> >> >
> >> > > >
> >> > > > Thanks,
> >> > > > Harish
> >> > > >
> >> > > Good question. I think most/all of the Intel adapters, - for which
> >>the app was
> >> > > originally written, way back in the day when there were only 2 PMDs
> >>in DPDK :)
> >> > > - will handle the promiscuous mode call either before or after the
> >>dev start.
> >> > > Assuming that's the case, and if it makes life easier for other
> >>driver writers,
> >> > > we should indeed standardize on one supported way of doing things -
> >>the way
> >> > > specified in the documentation being that one way, I would guess.
> >> > >
> >> > > So, e1000, ixgbe maintainers - do you see any issues with forcing
> >>the promiscuous
> >> > > mode set API to be called after the call to dev_start()?
> >> >
> >> > Not sure, why do we need to enforce that restriction?
> >> > Is there any problem with current way?
> 
> Yes, at least with the our driver/firmware interface. The port/device
> bring-up is carried out in a certain order which requires port config like
> promisc mode is called after dev_start().
> 
> >>
> >> It complicates things for driver writers is all,
> >
> >Not sure how?
> >All this replay is done at rte_ethdev layer.
> >Honestly, so far I don't remember any complaint about promisc on/off.
> >
> >> and conflicts slightly with
> >> what is stated in the docs.
> >
> >Update the docs? :)
> 
> Anyway, please let me know what you guys decide? If the app is changed
> then nothing needs to done on driver side. Otherwise I have to think of
> how to handle this.
> 

So you are saying that for your device if dev_ops->promiscuous_enable()
is called before dev_ops->dev_start(), it would cause  a problem right?
Konstantin