Re: [RFT] p54: implement multicast + arp req PS filter

[Max Filippov <jcmvbkbc@gmail.com>]

> > In the ARP case, when there's no other traffic on p54spi, all ARP requests
> > are dropped. But if there's some egress traffic from p54spi, filter seems
> > to work correctly: only ARP requests that match filter pass through.
> "no other traffic" sounds like a the psm filter at work, have you disabled
> it before starting the experiment?

I ran tests first without "iwconfig wlan0 power on", rebooted and re-ran them with PSM.
Didn't notice any difference.

And having ingress traffic only doesn't help ARPs to get through. They need egress to get in.
In other words: I saw ingress packets in tcpdump, but no ARPs matching filter among them.
But once packets start to go out of p54spi, ARPs matching filter get in. Looks very strange.

> > In the multicast case filter seems to work correctly, but it treats broadcast
> > as subject to that filtering too. By default only 01:00:5e:00:00:01 gets into
> > priv->mc_maclist, so we miss all broadcasts.
> ok, so we have to reserve a spot of ff:ff:ff:ff:ff:ff.

But currently that cancels ARP filtering completely.

> > These two filters seem to interfere:
> > - if we set ARP filter and multicast filter without broadcast, we miss all
> > ARPs if there's no egress traffic;
> > - if we set ARP filter and multicast filter with broadcast, or don't set
> > multicast filter at all we get all ARPs.
> > 
> > This effect does not depend on filter setup order.
> interesting, well a unnamed [but trustworthy] source told us that ST identified
> a problem with the arp/multicast filter some time ago, unfortunately I haven't
> seen any updated p54spi firmwares lately. Maybe this sagred stuff works?

"sagred stuff" ?

Thanks.
-- Max