[dpdk-dev] Question on examples/multi_process app

[Ananyev, Konstantin]

Hi everyone,

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Bruce Richardson
> Sent: Tuesday, March 22, 2016 9:38 PM
> To: Harish Patil
> Cc: dev at 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?
Konstantin



> 
> /Bruce