[dpdk-dev] [PATCH v4 1/3] lib/librte_ether: add support for port reset

[Thomas Monjalon]

2017-04-13 08:55, Zhao1, Wei:
> From: Ananyev, Konstantin
> > From: Zhao1, Wei
> > > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> > > > 2017-04-06 02:57, Zhao1, Wei:
> > > > > >   /**
> > > > > > > + * Reset an ethernet device when it's not working. One
> > > > > > > + scenario is, after PF
> > > > > > > + * port is down and up, the related VF port should be reset.
> > > > > > > + * The API will stop the port, clear the rx/tx queues,
> > > > > > > + re-setup the rx/tx
> > > > > > > + * queues, restart the port.
> > > > > >
> > > > > > s/The API/This function/
> > > > > >
> > > > > > Please explain exactly the responsibility of this function, and
> > > > > > how it is different from calling stop/configure/start.
> > > > >
> > > > > In this reset feature, reset function can do the calling
> > > > > stop/configure/start process, but also It can also do some restore
> > > > > work for the port, for example, it can restore the added
> > > > > parameters  of
> > > > vlan,  mac_addrs, promisc_unicast_enabled falg and
> > > > promisc_multicast_enabled flag.
> > 
> > Ok, but why start/stop can't do these things?
> > Konstantin
> 
> This is because in i40e PMD code, start and stop process do not have the process of store and restore
> the added key parameters. Not  only i40e but also other PMD code. So, in the function pointed to by dev_reset,
> we add specific function do store and restore of some of the important  parameters  listed above.

Why store and restore cannot be implemented in start/stop functions?