The vlan-offload support does not make any difference (tested on old hardware)
Installing kernel 2.6.38-10 (from lucid-updates) on a running lucid (10.04) system did break the vlan interface and a network bridge running on a vlan interface.
vlan support is now working on my oneiric system (a switch configuration error, my mistake). There is still a bug regarding vlans over a bridge, but that's documented in Bug #771209
A bit more testing.
The vlan-offload support does not make any difference (tested on old hardware)
Installing kernel 2.6.38-10 (from lucid-updates) on a running lucid (10.04) system did break the vlan interface and a network bridge running on a vlan interface.
vlan support is now working on my oneiric system (a switch configuration error, my mistake). There is still a bug regarding vlans over a bridge, but that's documented in Bug #771209