Subject: Re: zero features for a vlan over bond / vlan features

From: Or Gerlitz <[email-masked]>
Date: Thu, 16 Apr 2009 17:11:32 +0300

Jay Vosburgh wrote:
> The features system now has a dev->vlan_features that lists the
> features that will work through a vlan; bond_compute_features isn't
> using netdev_increment/fix_features to additionally compute the vlan_features, 
> so that's ending up always empty even if the underlying device supports vlan passthrough.
> I'm working on a patch; I'll see what I can come up with.  

Great, I will be happy to test the patch once you have it...

> Note, however, that at this writing, the set of drivers that explicitly
> supports VLAN passthrough (a non-zero vlan_features) is rather limited.

Please correct me if I'm wrong - would be it correct to say that there's a concept 
of "VLAN acceleration" which comes into play when the NIC device advertises  
NETIF_F_HW_VLAN_xxx features and a concept of "VLAN passthrough" which means the
NIC device have a non empty vlan_features bit mask? 

Looking on Linus tree I noted that indeed only few drivers have non-empty vlan_features
and I wonder if the reason for that is indeed lack of HW support or just the driver
maintainers being somehow slow to catch up with the vlan_features concept, Dave - 
any insight here? 

Or.