Transmitting 802.1p frames without 802.1q?

Hi Pedro, Eric, Patrick,

Commit ad1afb003939 vlan_dev: VLAN 0 should be treated as "no vlan
tag" (802.1p packet) did allow receiving 802.1p frames without
necessarily creating a VLAN w/ VID0 interface.

After setting up a VLAN interface with VID0, the packets are properly
tagged while being transmitted, but this also required the receiver to
have a  VLAN interface with VID0, which does not seem like it should
be required thanks to the above commit.

Should we have a special set of SO_PRIORITY values which will
automatically insert a VLAN tag with ID0 and PCP fields (like what
net/wireless/util.c::cfg80211_classify8021d does)?

Thanks!
-- 
Florian