Re: [PATCH v2] net: core: SIOCADDMULTI/SIOCDELMULTI distinguish between uc and mc
From: Denys Zagorui -X (dzagorui - GLOBALLOGIC INC at Cisco)
Date: Wed Aug 26 2020 - 10:45:09 EST
>This doesn't seem appropriate at all. If anything UC addresses
>should be blocked and the Intel driver change reverted. We have
>a well defined way to add secondary UC addresses and the MC interfaces
>are not it.
As I understand by ‘well defined way’ you mean macvlan feature. But macvlan
is more virtualisation thing where an additional netdevice is created and for each
skb passed to linux stack hash_lookup is made to find a netdevice to which this
skb belongs to based on mac_dst. In case if someone want to have a network
protocol on top of physical layer (AF_PACKET) where NIC should allow several uc
mac addr without enabling promiscuous mode i am not sure that for this simple
task macvlan is needed.
>Furthermore, even if this was appropriate, "fixing" this only for
>ethernet is definitely not appropriate. The fix would need to be able
>to handle any address type. Having a generic interface work
>inconsistently for one link type vs. another is a non-starter.
Maybe overusing multicast api isn’t the best choice for this purpose, but i noticed
that it is already overused by i40 for the same purpose, that is why i suggested
this diff. Anyway i can add separate ioctls for add/del secondary uc, if this is worth it.