Re: [PATCH net-next 1/2] net: stmmac: dwmac4: Read the UC filter size from hardware capabilities

[Andrew Lunn]

> Yeah but dwmac4 has a hash filter, but same as the UC filter it's just not plumbed
> in :/
> 
> Let's leave this flag here, hash filter addition for MC filtering is coming-up, so let's not
> drop it now only to re-enable it after, one of the other wonderful discoveries found by
> running the selftests...

I assume you can put a MC address in a perfect match filter? You can
perfectly match a multicast address just as well as a unicast address.

The hash filter is less accurate, but again can be used to match a
unicast or multicast address, and then you need additional filtering
in software, which Linux will do.

So it seems to me, you should use a perfect match filters if you have
one available, independent of unicast or multicast, and only use a
hash filter if you have run out of perfect match filters.

A IPv6 interface will be listening on a multicast address for
Neighbour discovery. It would be good to do a perfect match on it...

	  Andrew