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

["Zhao1, Wei" <wei.zhao1@intel.com>]

Add Thomas new mail address for this mail.

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Zhao1, Wei
> Sent: Monday, April 17, 2017 10:09 AM
> To: 'Thomas Monjalon' <thomas.monjalon@6wind.com>
> Cc: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Mcnamara, John
> <john.mcnamara@intel.com>; 'dev@dpdk.org' <dev@dpdk.org>; Lu,
> Wenzhuo <wenzhuo.lu@intel.com>
> Subject: Re: [dpdk-dev] [PATCH v4 1/3] lib/librte_ether: add support for port
> reset
> 
> Hi, Thomas
> 
>     All questions about this patch set has been answered, is it clear or not?And
> is there anything that I should do for it?
> Or it is OK for merge into 17.02-RC2?
> 
> Thank you.
> 
> > -----Original Message-----
> > From: Zhao1, Wei
> > Sent: Friday, April 14, 2017 4:03 PM
> > To: Thomas Monjalon <thomas.monjalon@6wind.com>
> > Cc: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Mcnamara,
> John
> > <john.mcnamara@intel.com>; dev@dpdk.org; Lu, Wenzhuo
> > <wenzhuo.lu@intel.com>
> > Subject: RE: [dpdk-dev] [PATCH v4 1/3] lib/librte_ether: add support
> > for port reset
> >
> > Hi, Thomas
> >
> > > -----Original Message-----
> > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > Sent: Friday, April 14, 2017 2:31 PM
> > > To: Zhao1, Wei <wei.zhao1@intel.com>
> > > Cc: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Mcnamara,
> > John
> > > <john.mcnamara@intel.com>; dev@dpdk.org; Lu, Wenzhuo
> > > <wenzhuo.lu@intel.com>
> > > Subject: Re: [dpdk-dev] [PATCH v4 1/3] lib/librte_ether: add support
> > > for port reset
> > >
> > > 2017-04-14 01:29, Zhao1, Wei:
> > > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > > > 2017-04-13 08:55, Zhao1, Wei:
> > > > > > From: Ananyev, Konstantin
> > > > > > > From: Zhao1, Wei
> > > > > > > > From: Thomas Monjalon [mailto:thomas.monjalon@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?
> > > >
> > > > Because reset and  start/stop are used for two purposes,  for example:
> > > > Some user maybe just start/stop the port  and he do not care what
> > > > key parameters has been configuration last time, and even worse
> > > > when he want to clear all the configuration last time , if we add
> > > > specific function do store and restore in  that two function, it
> > > > is useless for them,
> > > and may cause a result that user do not expect.
> > >
> > > Is it said somewhere in the doc that the configuration is lost when
> > > stopping a device?
> > > Can we say which configuration parameter is kept and which one is lost?
> > >
> > > rte_eth_dev_config_restore() is called in rte_eth_dev_start().
> >
> > Port reset process not only involve the rte_eth_dev_start() and
> > rte_eth_dev_stop().
> > It also involve eth_dev_uninit() and eth_dev_init() process，
> > in which PMD device uninit and init. In this case, for example, data-
> > >mac_addrs buffer is freed so it need to add store and restore function.
> > BUT, if you only call stop/configure/start process, that is not
> > strictly what named "device reset".