Re: [dpdk-dev] [PATCH] net/i40evf: add multicast MAC address filtering

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Yigit, Ferruh
> Sent: Wednesday, March 28, 2018 9:53 PM
> To: Zhang, Qi Z <qi.z.zhang@intel.com>; Olivier Matz
> <olivier.matz@6wind.com>; dev@dpdk.org; Xing, Beilei
> <beilei.xing@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>; Thomas
> Monjalon <thomas@monjalon.net>
> Subject: Re: [dpdk-dev] [PATCH] net/i40evf: add multicast MAC address
> filtering
> 
> On 3/28/2018 11:15 AM, Zhang, Qi Z wrote:
> > Hi Ferruh:
> >
> >> -----Original Message-----
> >> From: Yigit, Ferruh
> >> Sent: Wednesday, March 28, 2018 6:01 PM
> >> To: Zhang, Qi Z <qi.z.zhang@intel.com>; Olivier Matz
> >> <olivier.matz@6wind.com>; dev@dpdk.org; Xing, Beilei
> >> <beilei.xing@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>
> >> Subject: Re: [dpdk-dev] [PATCH] net/i40evf: add multicast MAC address
> >> filtering
> >>
> >> On 3/27/2018 2:51 PM, Zhang, Qi Z wrote:
> >>>
> >>>
> >>>> -----Original Message-----
> >>>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier Matz
> >>>> Sent: Thursday, January 25, 2018 10:36 PM
> >>>> To: dev@dpdk.org; Xing, Beilei <beilei.xing@intel.com>; Zhang, Qi Z
> >>>> <qi.z.zhang@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>
> >>>> Subject: [dpdk-dev] [PATCH] net/i40evf: add multicast MAC address
> >>>> filtering
> >>>>
> >>>> Add support the set_mc_addr_list device operation in the i40evf PMD.
> >>>>
> >>>> The configured addresses are stored in the device private area, so
> >>>> they can be flushed before adding new ones.
> >>>>
> >>>> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> >>>
> >>> Acked-by: Qi Zhang <qi.z.zhang@intel.com>
> >>>
> >>> Thanks for enable this!
> >>
> >> Hi Qi,
> >>
> >> This feature was already documented as supported in i40e_vf.ini which
> >> seems wrong but now it is supported.
> >>
> >> i40e also documents this feature as supported, can you please check
> >> if the feature is supported there and update i40e.ini if required?
> >
> > Do you mean
> >
> > " Multicast MAC filter = Y" ?
> >
> > My understanding is, though i40e PF/VF doesn't support set_mc_addr_list,
> but we still can use mac_addr_add to add a multi cast address, so we still
> have that flag on in i40e.ini.
> 
> Right, current "mac_addr_add" dev_ops lets setting multicast addresses. In
> this logic if HW supports setting multicast address PMD may claim this
> support.
> 
> Or this may explicitly mean implementing set_mc_addr_list dev_ops in
> driver.
> 
> 
> These feature list is to help user / application developer about what to expect
> and what to not from drivers.
> 
> A user may expect set_mc_addr_list dev_ops is implemented when this
> feature documented and it may be confusing when it fails.
> 
> Overall which information, hw supports setting mc mad address or
> set_mc_addr_list implemented, adds more value from user point of view?
> What do you think?

I'm not sure if it is feasible to bind "Multicast MAC filter = Y" to set_mc_addr_list's implementation only in document.
For me, I think it's reasonable to support two ways to enable mc filters
set_mc_addr_list support batch, but it also overwrite, in the case user don't want to overwrite, mac_addr_add could be taken.
so for i40e, it just not support batch overwrite and if just set "Multicast MAC filter = N" seems a little bit unfair to i40e, 
properly we should update the document?

> 
> >
> > Regards
> > Qi
> >
> >>
> >> Thanks,
> >> ferruh