MFC r227547:

The maximum TSO frame size should be:

maximum IP datagram size (65535 bytes) +
Ethernet header size (14 bytes) +
2 * VLAN tag size (4 bytes) [1].

[1] We need to multiply by 2 to account for the double VLAN tag

provision added in IEEE 802.1ad.

Submitted by: David Somayajulu (david.somayajulu qlogic.com)

Approved by: re (kib)